From: Roberto Sassu <[email protected]>
Introduce the digest_cache LSM, whose purpose is to deliver reference
digest values to integrity providers, such as IMA and IPE, abstracting to
them how those digests where extracted from the respective data source.
The major benefit is the ability to use the vaste amount of digests already
provided (and likely signed) by software vendors, without needing them to
adapt their format to the one understood by the integrity provider.
IMA and IPE can immediately interface with the digest_cache LSM and query
the digest of an accessed file. If the digest is found, it means that the
file is coming from the software vendor and not modified. If not, the file
might have been corrupted. Each integrity provider decides how to handle
this situation.
The second major benefit is performance improvement. Since the digest_cache
LSM has the ability to extract many digests from a single data source, it
means that it has less signatures to verify compared to the approach of
verifying individual file signatures (IMA appraisal). Preliminary tests
have shown a speedup of IMA appraisal of about 65% for sequential read, and
45% for parallel read.
This patch set has as prerequisites the file_release LSM hook (to be
introduced with the move of IMA/EVM to the LSM infrastructure), and
support for PGP keys, which is still unclear how it should be done.
The IMA integration patch set will be introduced separately. Also a PoC
based on the current version of IPE can be provided.
v2:
- Include the TLV parser in this patch set (from user asymmetric keys and
signatures)
- Move from IMA and make an independent LSM
- Remove IMA-specific stuff from this patch set
- Add per algorithm hash table
- Expect all digest lists to be in the same directory and allow changing
the default directory
- Support digest lookup on directories, when there is no
security.digest_list xattr
- Add seq num to digest list file name, to impose ordering on directory
iteration
- Add a new data type DIGEST_LIST_ENTRY_DATA for the nested data in the
tlv digest list format
- Add the concept of verification data attached to digest caches
- Add the reset mechanism to track changes on digest lists and directory
containing the digest lists
- Add kernel selftests
v1:
- Add documentation in Documentation/security/integrity-digest-cache.rst
- Pass the mask of IMA actions to digest_cache_alloc()
- Add a reference count to the digest cache
- Remove the path parameter from digest_cache_get(), and rely on the
reference count to avoid the digest cache disappearing while being used
- Rename the dentry_to_check parameter of digest_cache_get() to dentry
- Rename digest_cache_get() to digest_cache_new() and add
digest_cache_get() to set the digest cache in the iint of the inode for
which the digest cache was requested
- Add dig_owner and dig_user to the iint, to distinguish from which inode
the digest cache was created from, and which is using it; consequently it
makes the digest cache usable to measure/appraise other digest caches
(support not yet enabled)
- Add dig_owner_mutex and dig_user_mutex to serialize accesses to dig_owner
and dig_user until they are initialized
- Enforce strong synchronization and make the contenders wait until
dig_owner and dig_user are assigned to the iint the first time
- Move checking IMA actions on the digest list earlier, and fail if no
action were performed (digest cache not usable)
- Remove digest_cache_put(), not needed anymore with the introduction of
the reference count
- Fail immediately in digest_cache_lookup() if the digest algorithm is
not set in the digest cache
- Use 64 bit mask for IMA actions on the digest list instead of 8 bit
- Return NULL in the inline version of digest_cache_get()
- Use list_add_tail() instead of list_add() in the iterator
- Copy the digest list path to a separate buffer in digest_cache_iter_dir()
- Use digest list parsers verified with Frama-C
- Explicitly disable (for now) the possibility in the IMA policy to use the
digest cache to measure/appraise other digest lists
- Replace exit(<value>) with return <value> in manage_digest_lists.c
Roberto Sassu (13):
lib: Add TLV parser
security: Introduce the digest_cache LSM
digest_cache: Add securityfs interface
digest_cache: Add hash tables and operations
digest_cache: Populate the digest cache from a digest list
digest_cache: Parse tlv digest lists
digest_cache: Parse rpm digest lists
digest_cache: Add management of verification data
digest_cache: Add support for directories
digest cache: Prefetch digest lists if requested
digest_cache: Reset digest cache on file/directory change
selftests/digest_cache: Add selftests for digest_cache LSM
docs: Add documentation of the digest_cache LSM
Documentation/security/digest_cache.rst | 900 ++++++++++++++++++
Documentation/security/index.rst | 1 +
MAINTAINERS | 16 +
include/linux/digest_cache.h | 89 ++
include/linux/kernel_read_file.h | 1 +
include/linux/tlv_parser.h | 28 +
include/uapi/linux/lsm.h | 1 +
include/uapi/linux/tlv_digest_list.h | 72 ++
include/uapi/linux/tlv_parser.h | 59 ++
include/uapi/linux/xattr.h | 6 +
lib/Kconfig | 3 +
lib/Makefile | 3 +
lib/tlv_parser.c | 214 +++++
lib/tlv_parser.h | 17 +
security/Kconfig | 11 +-
security/Makefile | 1 +
security/digest_cache/Kconfig | 34 +
security/digest_cache/Makefile | 11 +
security/digest_cache/dir.c | 245 +++++
security/digest_cache/htable.c | 268 ++++++
security/digest_cache/internal.h | 259 +++++
security/digest_cache/main.c | 545 +++++++++++
security/digest_cache/modsig.c | 66 ++
security/digest_cache/parsers/parsers.h | 15 +
security/digest_cache/parsers/rpm.c | 223 +++++
security/digest_cache/parsers/tlv.c | 299 ++++++
security/digest_cache/populate.c | 163 ++++
security/digest_cache/reset.c | 168 ++++
security/digest_cache/secfs.c | 87 ++
security/digest_cache/verif.c | 119 +++
security/security.c | 3 +-
tools/testing/selftests/Makefile | 1 +
.../testing/selftests/digest_cache/.gitignore | 3 +
tools/testing/selftests/digest_cache/Makefile | 23 +
.../testing/selftests/digest_cache/all_test.c | 706 ++++++++++++++
tools/testing/selftests/digest_cache/common.c | 79 ++
tools/testing/selftests/digest_cache/common.h | 131 +++
.../selftests/digest_cache/common_user.c | 47 +
.../selftests/digest_cache/common_user.h | 17 +
tools/testing/selftests/digest_cache/config | 1 +
.../selftests/digest_cache/generators.c | 248 +++++
.../selftests/digest_cache/generators.h | 19 +
.../selftests/digest_cache/testmod/Makefile | 16 +
.../selftests/digest_cache/testmod/kern.c | 499 ++++++++++
.../selftests/lsm/lsm_list_modules_test.c | 3 +
45 files changed, 5714 insertions(+), 6 deletions(-)
create mode 100644 Documentation/security/digest_cache.rst
create mode 100644 include/linux/digest_cache.h
create mode 100644 include/linux/tlv_parser.h
create mode 100644 include/uapi/linux/tlv_digest_list.h
create mode 100644 include/uapi/linux/tlv_parser.h
create mode 100644 lib/tlv_parser.c
create mode 100644 lib/tlv_parser.h
create mode 100644 security/digest_cache/Kconfig
create mode 100644 security/digest_cache/Makefile
create mode 100644 security/digest_cache/dir.c
create mode 100644 security/digest_cache/htable.c
create mode 100644 security/digest_cache/internal.h
create mode 100644 security/digest_cache/main.c
create mode 100644 security/digest_cache/modsig.c
create mode 100644 security/digest_cache/parsers/parsers.h
create mode 100644 security/digest_cache/parsers/rpm.c
create mode 100644 security/digest_cache/parsers/tlv.c
create mode 100644 security/digest_cache/populate.c
create mode 100644 security/digest_cache/reset.c
create mode 100644 security/digest_cache/secfs.c
create mode 100644 security/digest_cache/verif.c
create mode 100644 tools/testing/selftests/digest_cache/.gitignore
create mode 100644 tools/testing/selftests/digest_cache/Makefile
create mode 100644 tools/testing/selftests/digest_cache/all_test.c
create mode 100644 tools/testing/selftests/digest_cache/common.c
create mode 100644 tools/testing/selftests/digest_cache/common.h
create mode 100644 tools/testing/selftests/digest_cache/common_user.c
create mode 100644 tools/testing/selftests/digest_cache/common_user.h
create mode 100644 tools/testing/selftests/digest_cache/config
create mode 100644 tools/testing/selftests/digest_cache/generators.c
create mode 100644 tools/testing/selftests/digest_cache/generators.h
create mode 100644 tools/testing/selftests/digest_cache/testmod/Makefile
create mode 100644 tools/testing/selftests/digest_cache/testmod/kern.c
--
2.34.1
From: Roberto Sassu <[email protected]>
Add a parser of a generic TLV format:
+-----------------+------------------+-----------------+
| data type (u64) | num fields (u64) | total len (u64) | # header
+--------------+--+---------+--------+---------+-------+
| field1 (u64) | len1 (u64) | value1 (u8 len1) |
+--------------+------------+------------------+
| ... | ... | ... | # data
+--------------+------------+------------------+
| fieldN (u64) | lenN (u64) | valueN (u8 lenN) |
+--------------+------------+------------------+
Each adopter can define its own data types and fields. The TLV parser does
not need to be aware of those, and calls a callback function with the
callback data, both supplied by the adopter, for every encountered field
during parsing. The adopter can decide in the callback function how each
defined field should be handled/parsed.
Normally, calling tlv_parse() is sufficient for most of the use cases. In
addition, tlv_parse_hdr() and tlv_parse_data() are also provided for more
advanced use cases.
Nesting TLVs is also possible, a callback function can call tlv_parse() to
parse the inner structure.
Signed-off-by: Roberto Sassu <[email protected]>
---
MAINTAINERS | 8 ++
include/linux/tlv_parser.h | 28 +++++
include/uapi/linux/tlv_parser.h | 59 +++++++++
lib/Kconfig | 3 +
lib/Makefile | 3 +
lib/tlv_parser.c | 214 ++++++++++++++++++++++++++++++++
lib/tlv_parser.h | 17 +++
7 files changed, 332 insertions(+)
create mode 100644 include/linux/tlv_parser.h
create mode 100644 include/uapi/linux/tlv_parser.h
create mode 100644 lib/tlv_parser.c
create mode 100644 lib/tlv_parser.h
diff --git a/MAINTAINERS b/MAINTAINERS
index ab4fbc0bf413..d3d13fb1004b 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -21946,6 +21946,14 @@ W: http://sourceforge.net/projects/tlan/
F: Documentation/networking/device_drivers/ethernet/ti/tlan.rst
F: drivers/net/ethernet/ti/tlan.*
+TLV PARSER
+M: Roberto Sassu <[email protected]>
+L: [email protected]
+S: Maintained
+F: include/linux/tlv_parser.h
+F: include/uapi/linux/tlv_parser.h
+F: lib/tlv_parser.*
+
TMIO/SDHI MMC DRIVER
M: Wolfram Sang <[email protected]>
L: [email protected]
diff --git a/include/linux/tlv_parser.h b/include/linux/tlv_parser.h
new file mode 100644
index 000000000000..565743b3cb30
--- /dev/null
+++ b/include/linux/tlv_parser.h
@@ -0,0 +1,28 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Header file of TLV parser.
+ */
+
+#ifndef _LINUX_TLV_PARSER_H
+#define _LINUX_TLV_PARSER_H
+
+#include <uapi/linux/tlv_parser.h>
+
+typedef int (*parse_callback)(void *, __u64, const __u8 *, __u64);
+
+int tlv_parse_hdr(const __u8 **data, size_t *data_len, __u64 *parsed_data_type,
+ __u64 *parsed_num_entries, __u64 *parsed_total_len,
+ const char **data_types, __u64 num_data_types);
+int tlv_parse_data(parse_callback callback, void *callback_data,
+ __u64 num_entries, const __u8 *data, size_t data_len,
+ const char **fields, __u64 num_fields);
+int tlv_parse(__u64 expected_data_type, parse_callback callback,
+ void *callback_data, const __u8 *data, size_t data_len,
+ const char **data_types, __u64 num_data_types,
+ const char **fields, __u64 num_fields);
+
+#endif /* _LINUX_TLV_PARSER_H */
diff --git a/include/uapi/linux/tlv_parser.h b/include/uapi/linux/tlv_parser.h
new file mode 100644
index 000000000000..3968c96f2518
--- /dev/null
+++ b/include/uapi/linux/tlv_parser.h
@@ -0,0 +1,59 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Implement the user space interface for the TLV parser.
+ */
+
+#ifndef _UAPI_LINUX_TLV_PARSER_H
+#define _UAPI_LINUX_TLV_PARSER_H
+
+#include <linux/types.h>
+
+/*
+ * TLV format:
+ *
+ * +-----------------+------------------+-----------------+
+ * | data type (u64) | num fields (u64) | total len (u64) | # header
+ * +--------------+--+---------+--------+---------+-------+
+ * | field1 (u64) | len1 (u64) | value1 (u8 len1) |
+ * +--------------+------------+------------------+
+ * | ... | ... | ... | # data
+ * +--------------+------------+------------------+
+ * | fieldN (u64) | lenN (u64) | valueN (u8 lenN) |
+ * +--------------+------------+------------------+
+ */
+
+/**
+ * struct tlv_hdr - Header of TLV format
+ * @data_type: Type of data to parse
+ * @num_entries: Number of data entries provided
+ * @_reserved: Reserved for future use (must be equal to zero)
+ * @total_len: Total length of the data blob, excluding the header
+ *
+ * This structure represents the header of the TLV data format.
+ */
+struct tlv_hdr {
+ __u64 data_type;
+ __u64 num_entries;
+ __u64 _reserved;
+ __u64 total_len;
+} __attribute__((packed));
+
+/**
+ * struct tlv_data_entry - Data entry of TLV format
+ * @field: Data field identifier
+ * @length: Data length
+ * @data: Data
+ *
+ * This structure represents a TLV entry of the data part of TLV data format.
+ */
+struct tlv_data_entry {
+ __u64 field;
+ __u64 length;
+ __u8 data[];
+} __attribute__((packed));
+
+#endif /* _UAPI_LINUX_TLV_PARSER_H */
diff --git a/lib/Kconfig b/lib/Kconfig
index 3ea1c830efab..22c833b2038d 100644
--- a/lib/Kconfig
+++ b/lib/Kconfig
@@ -775,3 +775,6 @@ config POLYNOMIAL
config FIRMWARE_TABLE
bool
+
+config TLV_PARSER
+ bool
diff --git a/lib/Makefile b/lib/Makefile
index 6b09731d8e61..23f0b770a639 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -444,3 +444,6 @@ $(obj)/$(TEST_FORTIFY_LOG): $(addprefix $(obj)/, $(TEST_FORTIFY_LOGS)) FORCE
ifeq ($(CONFIG_FORTIFY_SOURCE),y)
$(obj)/string.o: $(obj)/$(TEST_FORTIFY_LOG)
endif
+
+obj-$(CONFIG_TLV_PARSER) += tlv_parser.o
+CFLAGS_tlv_parser.o += -I lib
diff --git a/lib/tlv_parser.c b/lib/tlv_parser.c
new file mode 100644
index 000000000000..9565542932eb
--- /dev/null
+++ b/lib/tlv_parser.c
@@ -0,0 +1,214 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Implement the TLV parser.
+ */
+
+#define pr_fmt(fmt) "TLV PARSER: "fmt
+#include <tlv_parser.h>
+
+/**
+ * tlv_parse_hdr - Parse TLV header
+ * @data: Data to parse (updated)
+ * @data_len: Length of @data (updated)
+ * @parsed_data_type: Parsed data type (updated)
+ * @parsed_num_entries: Parsed number of data entries (updated)
+ * @parsed_total_len: Parsed length of TLV data, excluding the header (updated)
+ * @data_types: Array of data type strings
+ * @num_data_types: Number of elements of @data_types
+ *
+ * Parse the header of the TLV data format, move the data pointer to the TLV
+ * data part, decrease the data length by the length of the header, and provide
+ * the data type, number of entries and the total data length extracted from the
+ * header.
+ *
+ * Return: Zero on success, a negative value on error.
+ */
+int tlv_parse_hdr(const __u8 **data, size_t *data_len, __u64 *parsed_data_type,
+ __u64 *parsed_num_entries, __u64 *parsed_total_len,
+ const char **data_types, __u64 num_data_types)
+{
+ struct tlv_hdr *hdr;
+
+ if (*data_len < sizeof(*hdr)) {
+ pr_debug("Data blob too short, %lu bytes, expected %lu\n",
+ *data_len, sizeof(*hdr));
+ return -EBADMSG;
+ }
+
+ hdr = (struct tlv_hdr *)*data;
+
+ *data += sizeof(*hdr);
+ *data_len -= sizeof(*hdr);
+
+ *parsed_data_type = __be64_to_cpu(hdr->data_type);
+ if (*parsed_data_type >= num_data_types) {
+ pr_debug("Invalid data type %llu, max: %llu\n",
+ *parsed_data_type, num_data_types - 1);
+ return -EBADMSG;
+ }
+
+ *parsed_num_entries = __be64_to_cpu(hdr->num_entries);
+
+ if (hdr->_reserved != 0) {
+ pr_debug("_reserved must be zero\n");
+ return -EBADMSG;
+ }
+
+ *parsed_total_len = __be64_to_cpu(hdr->total_len);
+ if (*parsed_total_len > *data_len) {
+ pr_debug("Invalid total length %llu, expected: %lu\n",
+ *parsed_total_len, *data_len);
+ return -EBADMSG;
+ }
+
+ pr_debug("Header: type: %s, num entries: %llu, total len: %lld\n",
+ data_types[*parsed_data_type], *parsed_num_entries,
+ *parsed_total_len);
+
+ return 0;
+}
+
+/**
+ * tlv_parse_data - Parse TLV data
+ * @callback: Callback function to call to parse the entries
+ * @callback_data: Opaque data to supply to the callback function
+ * @num_entries: Number of data entries to parse
+ * @data: Data to parse
+ * @data_len: Length of @data
+ * @fields: Array of field strings
+ * @num_fields: Number of elements of @fields
+ *
+ * Parse the data part of the TLV data format and call the supplied callback
+ * function for each data entry, passing also the opaque data pointer.
+ *
+ * The callback function decides how to process data depending on the field.
+ *
+ * Return: Zero on success, a negative value on error.
+ */
+int tlv_parse_data(parse_callback callback, void *callback_data,
+ __u64 num_entries, const __u8 *data, size_t data_len,
+ const char **fields, __u64 num_fields)
+{
+ const __u8 *data_ptr = data;
+ struct tlv_data_entry *entry;
+ __u64 parsed_field, len, i, max_num_entries;
+ int ret;
+
+ max_num_entries = data_len / sizeof(*entry);
+
+ /* Finite termination on num_entries. */
+ if (num_entries > max_num_entries)
+ return -EBADMSG;
+
+ for (i = 0; i < num_entries; i++) {
+ if (data_len < sizeof(*entry))
+ return -EBADMSG;
+
+ entry = (struct tlv_data_entry *)data_ptr;
+ data_ptr += sizeof(*entry);
+ data_len -= sizeof(*entry);
+
+ parsed_field = __be64_to_cpu(entry->field);
+ if (parsed_field >= num_fields) {
+ pr_debug("Invalid field %llu, max: %llu\n",
+ parsed_field, num_fields - 1);
+ return -EBADMSG;
+ }
+
+ len = __be64_to_cpu(entry->length);
+
+ if (data_len < len)
+ return -EBADMSG;
+
+ pr_debug("Data: field: %s, len: %llu\n", fields[parsed_field],
+ len);
+
+ if (!len)
+ continue;
+
+ ret = callback(callback_data, parsed_field, data_ptr, len);
+ if (ret < 0) {
+ pr_debug("Parsing of field %s failed, ret: %d\n",
+ fields[parsed_field], ret);
+ return ret;
+ }
+
+ data_ptr += len;
+ data_len -= len;
+ }
+
+ if (data_len) {
+ pr_debug("Excess data: %lu bytes\n", data_len);
+ return -EBADMSG;
+ }
+
+ return 0;
+}
+
+/**
+ * tlv_parse - Parse data in TLV format
+ * @expected_data_type: Desired data type
+ * @callback: Callback function to call to parse the data entries
+ * @callback_data: Opaque data to supply to the callback function
+ * @data: Data to parse
+ * @data_len: Length of @data
+ * @data_types: Array of data type strings
+ * @num_data_types: Number of elements of @data_types
+ * @fields: Array of field strings
+ * @num_fields: Number of elements of @fields
+ *
+ * Parse data in TLV format and call tlv_parse_data() each time the header has
+ * the same data type as the expected one.
+ *
+ * Return: Zero on success, a negative value on error.
+ */
+int tlv_parse(__u64 expected_data_type, parse_callback callback,
+ void *callback_data, const __u8 *data, size_t data_len,
+ const char **data_types, __u64 num_data_types,
+ const char **fields, __u64 num_fields)
+{
+ __u64 parsed_data_type, parsed_num_entries, parsed_total_len;
+ const __u8 *data_ptr = data;
+ int ret = 0;
+
+ pr_debug("Start parsing data blob, size: %lu, expected data type: %s\n",
+ data_len, data_types[expected_data_type]);
+
+ while (data_len) {
+ ret = tlv_parse_hdr(&data_ptr, &data_len, &parsed_data_type,
+ &parsed_num_entries, &parsed_total_len,
+ data_types, num_data_types);
+ if (ret < 0)
+ goto out;
+
+ /* Skip data with a different data type than expected. */
+ if (parsed_data_type != expected_data_type) {
+ /*
+ * tlv_parse_hdr() already checked that
+ * parsed_total_len <= data_len.
+ */
+ data_ptr += parsed_total_len;
+ data_len -= parsed_total_len;
+ continue;
+ }
+
+ pr_debug("Found data type %s at offset %ld\n",
+ data_types[parsed_data_type], data_ptr - data);
+
+ ret = tlv_parse_data(callback, callback_data,
+ parsed_num_entries, data_ptr,
+ parsed_total_len, fields, num_fields);
+ if (ret < 0)
+ goto out;
+
+ data_ptr += parsed_total_len;
+ data_len -= parsed_total_len;
+ }
+out:
+ pr_debug("End of parsing data blob, ret: %d\n", ret);
+ return ret;
+}
diff --git a/lib/tlv_parser.h b/lib/tlv_parser.h
new file mode 100644
index 000000000000..8fa8127bd13e
--- /dev/null
+++ b/lib/tlv_parser.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Header file of TLV parser.
+ */
+
+#ifndef _LIB_TLV_PARSER_H
+#define _LIB_TLV_PARSER_H
+
+#include <linux/kernel.h>
+#include <linux/err.h>
+#include <linux/tlv_parser.h>
+
+#endif /* _LIB_TLV_PARSER_H */
--
2.34.1
From: Roberto Sassu <[email protected]>
Introduce the digest_cache LSM, to collect digests from various sources
(called digest lists), and to store them in kernel memory, in a set of hash
tables forming a digest cache. Extracted digests can be used as reference
values for integrity verification of file content or metadata.
A digest cache has three types of references: in the inode security blob of
the digest list the digest cache was created from (dig_owner field); in the
security blob of the inodes for which the digest cache is requested
(dig_user field); a reference returned by digest_cache_get().
References are released with digest_cache_put(), in the first two cases
when inodes are evicted from memory, in the last case when that function is
explicitly called. Obtaining a digest cache reference means that the digest
cache remains valid and cannot be freed until releasing it and until the
total number of references (stored in the digest cache) becomes zero.
When digest_cache_get() is called on an inode to compare its digest with
a reference value, the digest_cache LSM knows which digest cache to get
from the new security.digest_list xattr added to that inode, which contains
the file name of the desired digest list digests will be extracted from.
All digest lists are expected to be in the same directory, defined in the
kernel config, and modifiable (with a later patch) at run-time through
securityfs. When the digest_cache LSM reads the security.digest_list xattr,
it uses its value as last path component, appended to the default path
(unless the default path is a file). If an inode does not have that xattr,
the default path is considered as the final destination.
The default path can be either a file or a directory. If it is a file, the
digest_cache LSM always uses the same digest cache from that file to verify
all inodes (the xattr, if present, is ignored). If it is a directory, and
the inode to verify does not have the xattr, a subsequent patch will make
it possible to iterate and lookup on the digest caches created from each
directory entry.
Digest caches are created on demand, only when digest_cache_get() is
called. The first time a digest cache is requested, the digest_cache LSM
creates it and sets its reference in the dig_owner and dig_user fields of
the respective inode security blobs. On the next requests, the previously
set reference is returned, after incrementing the reference count.
Since there might be multiple digest_cache_get() calls for the same inode,
or for different inodes pointing to the same digest list, dig_owner_mutex
and dig_user_mutex have been introduced to protect the check and assignment
of the digest cache reference in the inode security blob.
Contenders that didn't get the lock also have to wait until the digest
cache is fully instantiated (when the bit INIT_IN_PROGRESS is cleared).
Dig_owner_mutex cannot be used for waiting on the instantiation to avoid
lock inversion with the inode lock for directories.
Signed-off-by: Roberto Sassu <[email protected]>
---
MAINTAINERS | 6 +
include/linux/digest_cache.h | 32 ++
include/uapi/linux/lsm.h | 1 +
include/uapi/linux/xattr.h | 3 +
security/Kconfig | 11 +-
security/Makefile | 1 +
security/digest_cache/Kconfig | 17 +
security/digest_cache/Makefile | 7 +
security/digest_cache/internal.h | 86 ++++
security/digest_cache/main.c | 397 ++++++++++++++++++
security/security.c | 3 +-
.../selftests/lsm/lsm_list_modules_test.c | 3 +
12 files changed, 561 insertions(+), 6 deletions(-)
create mode 100644 include/linux/digest_cache.h
create mode 100644 security/digest_cache/Kconfig
create mode 100644 security/digest_cache/Makefile
create mode 100644 security/digest_cache/internal.h
create mode 100644 security/digest_cache/main.c
diff --git a/MAINTAINERS b/MAINTAINERS
index d3d13fb1004b..3e3236dd0b26 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6155,6 +6155,12 @@ L: [email protected]
S: Maintained
F: drivers/gpio/gpio-gpio-mm.c
+DIGEST_CACHE LSM
+M: Roberto Sassu <[email protected]>
+L: [email protected]
+S: Maintained
+F: security/digest_cache/
+
DIGITEQ AUTOMOTIVE MGB4 V4L2 DRIVER
M: Martin Tuma <[email protected]>
L: [email protected]
diff --git a/include/linux/digest_cache.h b/include/linux/digest_cache.h
new file mode 100644
index 000000000000..e79f94a60b0f
--- /dev/null
+++ b/include/linux/digest_cache.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Public API of the digest_cache LSM.
+ */
+
+#ifndef _LINUX_DIGEST_CACHE_H
+#define _LINUX_DIGEST_CACHE_H
+
+#include <linux/fs.h>
+
+struct digest_cache;
+
+#ifdef CONFIG_SECURITY_DIGEST_CACHE
+struct digest_cache *digest_cache_get(struct dentry *dentry);
+void digest_cache_put(struct digest_cache *digest_cache);
+
+#else
+static inline struct digest_cache *digest_cache_get(struct dentry *dentry)
+{
+ return NULL;
+}
+
+static inline void digest_cache_put(struct digest_cache *digest_cache)
+{
+}
+
+#endif /* CONFIG_SECURITY_DIGEST_CACHE */
+#endif /* _LINUX_DIGEST_CACHE_H */
diff --git a/include/uapi/linux/lsm.h b/include/uapi/linux/lsm.h
index f8aef9ade549..205d969f20ff 100644
--- a/include/uapi/linux/lsm.h
+++ b/include/uapi/linux/lsm.h
@@ -62,6 +62,7 @@ struct lsm_ctx {
#define LSM_ID_LOCKDOWN 108
#define LSM_ID_BPF 109
#define LSM_ID_LANDLOCK 110
+#define LSM_ID_DIGEST_CACHE 111
/*
* LSM_ATTR_XXX definitions identify different LSM attributes
diff --git a/include/uapi/linux/xattr.h b/include/uapi/linux/xattr.h
index 9463db2dfa9d..8a58cf4bce65 100644
--- a/include/uapi/linux/xattr.h
+++ b/include/uapi/linux/xattr.h
@@ -54,6 +54,9 @@
#define XATTR_IMA_SUFFIX "ima"
#define XATTR_NAME_IMA XATTR_SECURITY_PREFIX XATTR_IMA_SUFFIX
+#define XATTR_DIGEST_LIST_SUFFIX "digest_list"
+#define XATTR_NAME_DIGEST_LIST XATTR_SECURITY_PREFIX XATTR_DIGEST_LIST_SUFFIX
+
#define XATTR_SELINUX_SUFFIX "selinux"
#define XATTR_NAME_SELINUX XATTR_SECURITY_PREFIX XATTR_SELINUX_SUFFIX
diff --git a/security/Kconfig b/security/Kconfig
index 52c9af08ad35..99f99cbd94cc 100644
--- a/security/Kconfig
+++ b/security/Kconfig
@@ -194,6 +194,7 @@ source "security/yama/Kconfig"
source "security/safesetid/Kconfig"
source "security/lockdown/Kconfig"
source "security/landlock/Kconfig"
+source "security/digest_cache/Kconfig"
source "security/integrity/Kconfig"
@@ -233,11 +234,11 @@ endchoice
config LSM
string "Ordered list of enabled LSMs"
- default "landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
- default "landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
- default "landlock,lockdown,yama,loadpin,safesetid,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
- default "landlock,lockdown,yama,loadpin,safesetid,bpf" if DEFAULT_SECURITY_DAC
- default "landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,bpf"
+ default "digest_cache,landlock,lockdown,yama,loadpin,safesetid,smack,selinux,tomoyo,apparmor,bpf" if DEFAULT_SECURITY_SMACK
+ default "digest_cache,landlock,lockdown,yama,loadpin,safesetid,apparmor,selinux,smack,tomoyo,bpf" if DEFAULT_SECURITY_APPARMOR
+ default "digest_cache,landlock,lockdown,yama,loadpin,safesetid,tomoyo,bpf" if DEFAULT_SECURITY_TOMOYO
+ default "digest_cache,landlock,lockdown,yama,loadpin,safesetid,bpf" if DEFAULT_SECURITY_DAC
+ default "digest_cache,landlock,lockdown,yama,loadpin,safesetid,selinux,smack,tomoyo,apparmor,bpf"
help
A comma-separated list of LSMs, in initialization order.
Any LSMs left off this list, except for those with order
diff --git a/security/Makefile b/security/Makefile
index 59f238490665..e9b43e7b715a 100644
--- a/security/Makefile
+++ b/security/Makefile
@@ -25,6 +25,7 @@ obj-$(CONFIG_SECURITY_LOCKDOWN_LSM) += lockdown/
obj-$(CONFIG_CGROUPS) += device_cgroup.o
obj-$(CONFIG_BPF_LSM) += bpf/
obj-$(CONFIG_SECURITY_LANDLOCK) += landlock/
+obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache/
# Object integrity file lists
obj-$(CONFIG_INTEGRITY) += integrity/
diff --git a/security/digest_cache/Kconfig b/security/digest_cache/Kconfig
new file mode 100644
index 000000000000..0c47d5151f07
--- /dev/null
+++ b/security/digest_cache/Kconfig
@@ -0,0 +1,17 @@
+# SPDX-License-Identifier: GPL-2.0
+config SECURITY_DIGEST_CACHE
+ bool "Digest_cache LSM"
+ default n
+ help
+ This option enables an LSM maintaining a cache of digests
+ (e.g. of file content or metadata).
+
+ This LSM can support other kernel components in making access
+ control decisions.
+
+config DIGEST_LIST_DEFAULT_PATH
+ string
+ default "/etc/digest_lists"
+ help
+ Default directory where digest_cache LSM expects to find digest
+ lists.
diff --git a/security/digest_cache/Makefile b/security/digest_cache/Makefile
new file mode 100644
index 000000000000..48848c41253e
--- /dev/null
+++ b/security/digest_cache/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0
+#
+# Makefile for building the digest_cache LSM.
+
+obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache.o
+
+digest_cache-y := main.o
diff --git a/security/digest_cache/internal.h b/security/digest_cache/internal.h
new file mode 100644
index 000000000000..5f04844af3a5
--- /dev/null
+++ b/security/digest_cache/internal.h
@@ -0,0 +1,86 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Internal header of the digest_cache LSM.
+ */
+
+#ifndef _DIGEST_CACHE_INTERNAL_H
+#define _DIGEST_CACHE_INTERNAL_H
+
+#include <linux/lsm_hooks.h>
+#include <linux/digest_cache.h>
+
+/* Digest cache bits in flags. */
+#define INIT_IN_PROGRESS 0 /* Digest cache being initialized. */
+
+/**
+ * struct digest_cache - Digest cache
+ * @ref_count: Number of references to the digest cache
+ * @path_str: Path of the digest list the digest cache was created from
+ * @flags: Control flags
+ *
+ * This structure represents a cache of digests extracted from a digest list.
+ */
+struct digest_cache {
+ atomic_t ref_count;
+ char *path_str;
+ unsigned long flags;
+};
+
+/**
+ * struct digest_cache_security - Digest cache pointers in inode security blob
+ * @dig_owner: Digest cache created from this inode
+ * @dig_owner_mutex: Protects @dig_owner
+ * @dig_user: Digest cache requested for this inode
+ * @dig_user_mutex: Protects @dig_user
+ *
+ * This structure contains references to digest caches, protected by their
+ * respective mutex.
+ */
+struct digest_cache_security {
+ struct digest_cache *dig_owner;
+ struct mutex dig_owner_mutex;
+ struct digest_cache *dig_user;
+ struct mutex dig_user_mutex;
+};
+
+extern struct lsm_blob_sizes digest_cache_blob_sizes;
+extern char *default_path_str;
+
+static inline struct digest_cache_security *
+digest_cache_get_security(const struct inode *inode)
+{
+ if (unlikely(!inode->i_security))
+ return NULL;
+
+ return inode->i_security + digest_cache_blob_sizes.lbs_inode;
+}
+
+static inline struct digest_cache *
+digest_cache_ref(struct digest_cache *digest_cache)
+{
+ atomic_inc(&digest_cache->ref_count);
+ pr_debug("Ref (+) digest cache %s (ref count: %d)\n",
+ digest_cache->path_str, atomic_read(&digest_cache->ref_count));
+ return digest_cache;
+}
+
+static inline struct digest_cache *
+digest_cache_unref(struct digest_cache *digest_cache)
+{
+ bool ref_is_zero = atomic_dec_and_test(&digest_cache->ref_count);
+
+ pr_debug("Ref (-) digest cache %s (ref count: %d)\n",
+ digest_cache->path_str, atomic_read(&digest_cache->ref_count));
+ return (ref_is_zero) ? digest_cache : NULL;
+}
+
+/* main.c */
+struct digest_cache *digest_cache_create(struct dentry *dentry,
+ struct path *digest_list_path,
+ char *path_str, char *filename);
+
+#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/digest_cache/main.c b/security/digest_cache/main.c
new file mode 100644
index 000000000000..166798e6247e
--- /dev/null
+++ b/security/digest_cache/main.c
@@ -0,0 +1,397 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Implement the main code of the digest_cache LSM.
+ */
+
+#define pr_fmt(fmt) "DIGEST CACHE: "fmt
+#include <linux/namei.h>
+#include <linux/xattr.h>
+
+#include "internal.h"
+
+static int digest_cache_enabled __ro_after_init = 1;
+static struct kmem_cache *digest_cache_cache __read_mostly;
+
+char *default_path_str = CONFIG_DIGEST_LIST_DEFAULT_PATH;
+
+/**
+ * digest_cache_alloc_init - Allocate and initialize a new digest cache
+ * @path_str: Path string of the digest list
+ * @filename: Digest list file name (can be an empty string)
+ *
+ * This function allocates and initializes a new digest cache.
+ *
+ * Return: A digest_cache structure on success, NULL on error.
+ */
+static struct digest_cache *digest_cache_alloc_init(char *path_str,
+ char *filename)
+{
+ struct digest_cache *digest_cache;
+
+ digest_cache = kmem_cache_alloc(digest_cache_cache, GFP_KERNEL);
+ if (!digest_cache)
+ return digest_cache;
+
+ digest_cache->path_str = kasprintf(GFP_KERNEL, "%s%s%s", path_str,
+ filename[0] ? "/" : "", filename);
+ if (!digest_cache->path_str) {
+ kmem_cache_free(digest_cache_cache, digest_cache);
+ return NULL;
+ }
+
+ atomic_set(&digest_cache->ref_count, 1);
+ digest_cache->flags = 0UL;
+
+ pr_debug("New digest cache %s (ref count: %d)\n",
+ digest_cache->path_str, atomic_read(&digest_cache->ref_count));
+
+ return digest_cache;
+}
+
+/**
+ * digest_cache_free - Free all memory occupied by the digest cache
+ * @digest_cache: Digest cache
+ *
+ * This function frees the memory occupied by the digest cache.
+ */
+static void digest_cache_free(struct digest_cache *digest_cache)
+{
+ pr_debug("Freed digest cache %s\n", digest_cache->path_str);
+ kfree(digest_cache->path_str);
+ kmem_cache_free(digest_cache_cache, digest_cache);
+}
+
+/**
+ * digest_cache_create - Create a digest cache
+ * @dentry: Dentry of the inode for which the digest cache will be used
+ * @digest_list_path: Path structure of the digest list
+ * @path_str: Path string of the digest list
+ * @filename: Digest list file name (can be an empty string)
+ *
+ * This function first locates, from the passed path, the digest list inode
+ * from which the digest cache will be created or retrieved (if it already
+ * exists).
+ *
+ * If dig_owner is NULL in the inode security blob, this function creates a
+ * new digest cache with reference count set to 1 (reference returned), sets
+ * it to dig_owner and consequently increments again the digest cache reference
+ * count.
+ *
+ * Otherwise, it simply increments the reference count of the existing
+ * dig_owner, since that reference is returned to the caller.
+ *
+ * Incrementing the reference count twice before calling path_put() ensures
+ * that the digest cache returned is valid even if the inode is evicted from
+ * memory (which decreases the reference count).
+ *
+ * Releasing the dig_owner_mutex lock does not mean that the digest cache is
+ * ready for use. digest_cache_create() callers that found a partially
+ * instantiated digest cache have to wait until the INIT_IN_PROGRESS bit is
+ * cleared by the caller that is actually creating that digest cache.
+ *
+ * Return: A new digest cache on success, NULL on error.
+ */
+struct digest_cache *digest_cache_create(struct dentry *dentry,
+ struct path *digest_list_path,
+ char *path_str, char *filename)
+{
+ struct path file_path;
+ struct digest_cache *digest_cache = NULL;
+ struct digest_cache_security *dig_sec;
+ struct inode *inode = d_backing_inode(digest_list_path->dentry);
+ bool dig_owner_exists = false;
+ int ret;
+
+ if (S_ISDIR(d_backing_inode(digest_list_path->dentry)->i_mode) &&
+ filename[0]) {
+ ret = vfs_path_lookup(digest_list_path->dentry,
+ digest_list_path->mnt, filename, 0,
+ &file_path);
+ if (ret < 0) {
+ pr_debug("Cannot find digest list %s/%s\n", path_str,
+ filename);
+ return NULL;
+ }
+
+ digest_list_path = &file_path;
+ inode = d_backing_inode(file_path.dentry);
+
+ /*
+ * Cannot request a digest cache for the same inode the
+ * digest cache is populated from.
+ */
+ if (d_backing_inode(dentry) == inode)
+ return NULL;
+
+ /* No support for nested directories. */
+ if (!S_ISREG(inode->i_mode))
+ return NULL;
+ }
+
+ dig_sec = digest_cache_get_security(inode);
+ if (unlikely(!dig_sec))
+ goto out;
+
+ /* Serialize check and assignment of dig_owner. */
+ mutex_lock(&dig_sec->dig_owner_mutex);
+ if (dig_sec->dig_owner) {
+ /* Increment ref. count for reference returned to the caller. */
+ digest_cache = digest_cache_ref(dig_sec->dig_owner);
+ dig_owner_exists = true;
+ mutex_unlock(&dig_sec->dig_owner_mutex);
+ goto exists;
+ }
+
+ /* Ref. count is already 1 for this reference. */
+ digest_cache = digest_cache_alloc_init(path_str, filename);
+ if (!digest_cache) {
+ mutex_unlock(&dig_sec->dig_owner_mutex);
+ goto out;
+ }
+
+ /* Increment ref. count for reference set to dig_owner. */
+ dig_sec->dig_owner = digest_cache_ref(digest_cache);
+
+ /* Make the other lock contenders wait until creation complete. */
+ set_bit(INIT_IN_PROGRESS, &dig_sec->dig_owner->flags);
+ mutex_unlock(&dig_sec->dig_owner_mutex);
+
+ /* Creation complete, notify the other lock contenders. */
+ clear_and_wake_up_bit(INIT_IN_PROGRESS, &dig_sec->dig_owner->flags);
+exists:
+ if (dig_owner_exists)
+ /* Wait until creation complete. */
+ wait_on_bit(&dig_sec->dig_owner->flags, INIT_IN_PROGRESS,
+ TASK_UNINTERRUPTIBLE);
+out:
+ if (digest_list_path == &file_path)
+ path_put(&file_path);
+
+ return digest_cache;
+}
+
+/**
+ * digest_cache_new - Retrieve digest list file name and request digest cache
+ * @dentry: Dentry of the inode for which the digest cache will be used
+ *
+ * This function locates the default path. If it is a file, it directly creates
+ * a digest cache from it. Otherwise, it reads the digest list file name from
+ * the security.digest_list xattr and requests the creation of a digest cache
+ * with that file name. If security.digest_list is not found, this function
+ * requests the creation of a digest cache on the parent directory.
+ *
+ * Return: A new digest cache on success, NULL on error.
+ */
+static struct digest_cache *digest_cache_new(struct dentry *dentry)
+{
+ char filename[NAME_MAX + 1] = { 0 };
+ struct digest_cache *digest_cache = NULL;
+ struct path default_path;
+ int ret;
+
+ ret = kern_path(default_path_str, 0, &default_path);
+ if (ret < 0) {
+ pr_debug("Cannot find path %s\n", default_path_str);
+ return NULL;
+ }
+
+ /* The default path is a file, no need to get xattr. */
+ if (S_ISREG(d_backing_inode(default_path.dentry)->i_mode)) {
+ pr_debug("Default path %s is a file, not reading %s xattr\n",
+ default_path_str, XATTR_NAME_DIGEST_LIST);
+ goto create;
+ } else if (!S_ISDIR(d_backing_inode(default_path.dentry)->i_mode)) {
+ pr_debug("Default path %s must be either a file or a directory\n",
+ default_path_str);
+ goto out;
+ }
+
+ ret = vfs_getxattr(&nop_mnt_idmap, dentry, XATTR_NAME_DIGEST_LIST,
+ filename, sizeof(filename) - 1);
+ if (ret <= 0) {
+ pr_debug("Digest list path not found for file %s, using %s\n",
+ dentry->d_name.name, default_path_str);
+ goto create;
+ }
+
+ if (strchr(filename, '/')) {
+ pr_debug("%s xattr should contain only a file name, got: %s\n",
+ XATTR_NAME_DIGEST_LIST, filename);
+ goto out;
+ }
+
+ pr_debug("Found %s xattr in %s, default path: %s, digest list: %s\n",
+ XATTR_NAME_DIGEST_LIST, dentry->d_name.name, default_path_str,
+ filename);
+create:
+ digest_cache = digest_cache_create(dentry, &default_path,
+ default_path_str, filename);
+out:
+ path_put(&default_path);
+ return digest_cache;
+}
+
+/**
+ * digest_cache_get - Get a digest cache for a given inode
+ * @dentry: Dentry of the inode for which the digest cache will be used
+ *
+ * This function tries to find a digest cache from the inode security blob of
+ * the passed dentry (dig_user field). If a digest cache was not found, it calls
+ * digest_cache_new() to create a new one. In both cases, it increments the
+ * digest cache reference count before returning the reference to the caller.
+ *
+ * The caller is responsible to call digest_cache_put() to release the digest
+ * cache reference returned.
+ *
+ * Lock dig_user_mutex to protect against concurrent requests to obtain a digest
+ * cache for the same inode, and to make other contenders wait until the first
+ * requester finishes the process.
+ *
+ * Return: A digest cache on success, NULL otherwise.
+ */
+struct digest_cache *digest_cache_get(struct dentry *dentry)
+{
+ struct digest_cache_security *dig_sec;
+ struct digest_cache *digest_cache = NULL;
+
+ if (!digest_cache_enabled)
+ return NULL;
+
+ dig_sec = digest_cache_get_security(d_backing_inode(dentry));
+ if (unlikely(!dig_sec))
+ return NULL;
+
+ /* Serialize accesses to inode for which the digest cache is used. */
+ mutex_lock(&dig_sec->dig_user_mutex);
+ if (!dig_sec->dig_user)
+ /* Consume extra reference from digest_cache_create(). */
+ dig_sec->dig_user = digest_cache_new(dentry);
+
+ if (dig_sec->dig_user)
+ /* Increment ref. count for reference returned to the caller. */
+ digest_cache = digest_cache_ref(dig_sec->dig_user);
+
+ mutex_unlock(&dig_sec->dig_user_mutex);
+ return digest_cache;
+}
+EXPORT_SYMBOL_GPL(digest_cache_get);
+
+/**
+ * digest_cache_put - Release a digest cache reference
+ * @digest_cache: Digest cache
+ *
+ * This function decrements the reference count of the digest cache passed as
+ * argument. If the reference count reaches zero, it calls digest_cache_free()
+ * to free the digest cache.
+ */
+void digest_cache_put(struct digest_cache *digest_cache)
+{
+ struct digest_cache *to_free;
+
+ to_free = digest_cache_unref(digest_cache);
+ if (!to_free)
+ return;
+
+ digest_cache_free(to_free);
+}
+EXPORT_SYMBOL_GPL(digest_cache_put);
+
+struct lsm_blob_sizes digest_cache_blob_sizes __ro_after_init = {
+ .lbs_inode = sizeof(struct digest_cache_security),
+};
+
+/**
+ * digest_cache_inode_alloc_security - Initialize inode security blob
+ * @inode: Inode for which the security blob is initialized
+ *
+ * This function initializes the digest_cache_security structure, directly
+ * stored in the inode security blob.
+ *
+ * Return: Zero.
+ */
+static int digest_cache_inode_alloc_security(struct inode *inode)
+{
+ struct digest_cache_security *dig_sec;
+
+ /* The inode security blob is always allocated here. */
+ dig_sec = digest_cache_get_security(inode);
+ mutex_init(&dig_sec->dig_owner_mutex);
+ mutex_init(&dig_sec->dig_user_mutex);
+ return 0;
+}
+
+/**
+ * digest_cache_inode_free_security - Release the digest cache references
+ * @inode: Inode for which the digest cache references are released
+ *
+ * Since the inode is being evicted, this function releases the non-needed
+ * references to the digest_caches stored in the digest_cache_security
+ * structure.
+ */
+static void digest_cache_inode_free_security(struct inode *inode)
+{
+ struct digest_cache_security *dig_sec;
+
+ dig_sec = digest_cache_get_security(inode);
+ if (!dig_sec)
+ return;
+
+ mutex_destroy(&dig_sec->dig_owner_mutex);
+ mutex_destroy(&dig_sec->dig_user_mutex);
+ if (dig_sec->dig_owner)
+ digest_cache_put(dig_sec->dig_owner);
+ if (dig_sec->dig_user)
+ digest_cache_put(dig_sec->dig_user);
+}
+
+static struct security_hook_list digest_cache_hooks[] __ro_after_init = {
+ LSM_HOOK_INIT(inode_alloc_security, digest_cache_inode_alloc_security),
+ LSM_HOOK_INIT(inode_free_security, digest_cache_inode_free_security),
+};
+
+/**
+ * digest_cache_init_once - Initialize the digest cache structure
+ * @foo: Digest cache structure to initialize
+ *
+ * This function fills the digest cache structure with zeros.
+ */
+static void digest_cache_init_once(void *foo)
+{
+ struct digest_cache *digest_cache = (struct digest_cache *)foo;
+
+ memset(digest_cache, 0, sizeof(*digest_cache));
+}
+
+static const struct lsm_id digest_cache_lsmid = {
+ .name = "digest_cache",
+ .id = LSM_ID_DIGEST_CACHE,
+};
+
+/**
+ * digest_cache_init - Initialize the digest_cache LSM
+ *
+ * Initialize the digest_cache LSM, by instantiating a cache for the
+ * digest_cache structure and by registering the digest_cache LSM hooks.
+ */
+static int __init digest_cache_init(void)
+{
+ digest_cache_cache = kmem_cache_create("digest_cache_cache",
+ sizeof(struct digest_cache),
+ 0, SLAB_PANIC,
+ digest_cache_init_once);
+
+ security_add_hooks(digest_cache_hooks, ARRAY_SIZE(digest_cache_hooks),
+ &digest_cache_lsmid);
+ return 0;
+}
+
+DEFINE_LSM(digest_cache) = {
+ .name = "digest_cache",
+ .enabled = &digest_cache_enabled,
+ .init = digest_cache_init,
+ .blobs = &digest_cache_blob_sizes,
+};
diff --git a/security/security.c b/security/security.c
index da827d7cbad8..570f52d534f8 100644
--- a/security/security.c
+++ b/security/security.c
@@ -50,7 +50,8 @@
(IS_ENABLED(CONFIG_SECURITY_SAFESETID) ? 1 : 0) + \
(IS_ENABLED(CONFIG_SECURITY_LOCKDOWN_LSM) ? 1 : 0) + \
(IS_ENABLED(CONFIG_BPF_LSM) ? 1 : 0) + \
- (IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0))
+ (IS_ENABLED(CONFIG_SECURITY_LANDLOCK) ? 1 : 0) + \
+ (IS_ENABLED(CONFIG_SECURITY_DIGEST_CACHE) ? 1 : 0))
/*
* These are descriptions of the reasons that can be passed to the
diff --git a/tools/testing/selftests/lsm/lsm_list_modules_test.c b/tools/testing/selftests/lsm/lsm_list_modules_test.c
index 9df29b1e3497..24fb9c038434 100644
--- a/tools/testing/selftests/lsm/lsm_list_modules_test.c
+++ b/tools/testing/selftests/lsm/lsm_list_modules_test.c
@@ -122,6 +122,9 @@ TEST(correct_lsm_list_modules)
case LSM_ID_LANDLOCK:
name = "landlock";
break;
+ case LSM_ID_DIGEST_CACHE:
+ name = "digest_cache";
+ break;
default:
name = "INVALID";
break;
--
2.34.1
From: Roberto Sassu <[email protected]>
Add the digest_cache_path file in securityfs, to let root change/read the
default path (file or directory) from where digest lists are looked up.
An RW semaphore prevents the default path from changing while
digest_list_new() and read_default_path() are executed, so that those read
a stable value. Multiple digest_list_new() and read_default_path() calls,
instead, can be done in parallel, since they are the readers.
Changing the default path does not affect digest caches created with the
old path.
Signed-off-by: Roberto Sassu <[email protected]>
---
security/digest_cache/Kconfig | 4 ++
security/digest_cache/Makefile | 2 +-
security/digest_cache/internal.h | 1 +
security/digest_cache/main.c | 10 +++-
security/digest_cache/secfs.c | 87 ++++++++++++++++++++++++++++++++
5 files changed, 102 insertions(+), 2 deletions(-)
create mode 100644 security/digest_cache/secfs.c
diff --git a/security/digest_cache/Kconfig b/security/digest_cache/Kconfig
index 0c47d5151f07..2f361c7844df 100644
--- a/security/digest_cache/Kconfig
+++ b/security/digest_cache/Kconfig
@@ -15,3 +15,7 @@ config DIGEST_LIST_DEFAULT_PATH
help
Default directory where digest_cache LSM expects to find digest
lists.
+
+ It can be changed at run-time, by writing the new path to the
+ securityfs interface. Digest caches created with the old path are
+ not affected by the change.
diff --git a/security/digest_cache/Makefile b/security/digest_cache/Makefile
index 48848c41253e..1330655e33b1 100644
--- a/security/digest_cache/Makefile
+++ b/security/digest_cache/Makefile
@@ -4,4 +4,4 @@
obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache.o
-digest_cache-y := main.o
+digest_cache-y := main.o secfs.o
diff --git a/security/digest_cache/internal.h b/security/digest_cache/internal.h
index 5f04844af3a5..bbf5eefe5c82 100644
--- a/security/digest_cache/internal.h
+++ b/security/digest_cache/internal.h
@@ -49,6 +49,7 @@ struct digest_cache_security {
extern struct lsm_blob_sizes digest_cache_blob_sizes;
extern char *default_path_str;
+extern struct rw_semaphore default_path_sem;
static inline struct digest_cache_security *
digest_cache_get_security(const struct inode *inode)
diff --git a/security/digest_cache/main.c b/security/digest_cache/main.c
index 166798e6247e..8bae2e91ac4c 100644
--- a/security/digest_cache/main.c
+++ b/security/digest_cache/main.c
@@ -18,6 +18,9 @@ static struct kmem_cache *digest_cache_cache __read_mostly;
char *default_path_str = CONFIG_DIGEST_LIST_DEFAULT_PATH;
+/* Protects default_path_str. */
+struct rw_semaphore default_path_sem;
+
/**
* digest_cache_alloc_init - Allocate and initialize a new digest cache
* @path_str: Path string of the digest list
@@ -267,9 +270,12 @@ struct digest_cache *digest_cache_get(struct dentry *dentry)
/* Serialize accesses to inode for which the digest cache is used. */
mutex_lock(&dig_sec->dig_user_mutex);
- if (!dig_sec->dig_user)
+ if (!dig_sec->dig_user) {
+ down_read(&default_path_sem);
/* Consume extra reference from digest_cache_create(). */
dig_sec->dig_user = digest_cache_new(dentry);
+ up_read(&default_path_sem);
+ }
if (dig_sec->dig_user)
/* Increment ref. count for reference returned to the caller. */
@@ -379,6 +385,8 @@ static const struct lsm_id digest_cache_lsmid = {
*/
static int __init digest_cache_init(void)
{
+ init_rwsem(&default_path_sem);
+
digest_cache_cache = kmem_cache_create("digest_cache_cache",
sizeof(struct digest_cache),
0, SLAB_PANIC,
diff --git a/security/digest_cache/secfs.c b/security/digest_cache/secfs.c
new file mode 100644
index 000000000000..d3a37bf3588e
--- /dev/null
+++ b/security/digest_cache/secfs.c
@@ -0,0 +1,87 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Implement the securityfs interface of the digest_cache LSM.
+ */
+
+#define pr_fmt(fmt) "DIGEST CACHE: "fmt
+#include <linux/security.h>
+
+#include "internal.h"
+
+static struct dentry *default_path_dentry;
+
+/**
+ * write_default_path - Write default path
+ * @file: File descriptor of the securityfs file
+ * @buf: User space buffer
+ * @datalen: Amount of data to write
+ * @ppos: Current position in the file
+ *
+ * This function sets the new default path where digest lists can be found.
+ * Can be either a regular file or a directory.
+ *
+ * Return: Length of path written on success, a POSIX error code otherwise.
+ */
+static ssize_t write_default_path(struct file *file, const char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ char *new_default_path_str;
+
+ new_default_path_str = memdup_user_nul(buf, datalen);
+ if (IS_ERR(new_default_path_str))
+ return PTR_ERR(new_default_path_str);
+
+ down_write(&default_path_sem);
+ kfree_const(default_path_str);
+ default_path_str = new_default_path_str;
+ up_write(&default_path_sem);
+ return datalen;
+}
+
+/**
+ * read_default_path - Read default path
+ * @file: File descriptor of the securityfs file
+ * @buf: User space buffer
+ * @datalen: Amount of data to read
+ * @ppos: Current position in the file
+ *
+ * This function returns the current default path where digest lists can be
+ * found. Can be either a regular file or a directory.
+ *
+ * Return: Length of path read on success, a POSIX error code otherwise.
+ */
+static ssize_t read_default_path(struct file *file, char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ int ret;
+
+ down_read(&default_path_sem);
+ ret = simple_read_from_buffer(buf, datalen, ppos, default_path_str,
+ strlen(default_path_str) + 1);
+ up_read(&default_path_sem);
+ return ret;
+}
+
+static const struct file_operations default_path_ops = {
+ .open = generic_file_open,
+ .write = write_default_path,
+ .read = read_default_path,
+ .llseek = generic_file_llseek,
+};
+
+static int __init digest_cache_path_init(void)
+{
+ default_path_dentry = securityfs_create_file("digest_cache_path", 0660,
+ NULL, NULL,
+ &default_path_ops);
+ if (IS_ERR(default_path_dentry))
+ return -EFAULT;
+
+ return 0;
+}
+
+late_initcall(digest_cache_path_init);
--
2.34.1
From: Roberto Sassu <[email protected]>
Add a linked list of hash tables to the digest cache, one per algorithm,
containing the digests extracted from digest lists.
The number of hash table slots is determined by dividing the number of
digests to add to the average depth of the collision list defined with
CONFIG_DIGEST_CACHE_HTABLE_DEPTH (currently set to 30). It can be changed
in the kernel configuration.
Add digest_cache_htable_init() and digest_cache_htable_add(), to be called
by digest list parsers, in order to allocate the hash tables and to add
extracted digests.
Add digest_cache_htable_free(), to let the digest_cache LSM free the hash
tables at the time a digest cache is freed.
Add digest_cache_htable_lookup() to search a digest in the hash table of a
digest cache for a given algorithm.
Add digest_cache_lookup() to the public API, to let users of the
digest_cache LSM search a digest in a digest cache and, in a subsequent
patch, to search it in the digest caches for each directory entry.
Return the digest cache containing the digest, as a different type,
digest_cache_found_t to avoid it being accidentally put. Also, introduce
digest_cache_from_found_t() to explicitly convert it back to a digest cache
for further use (e.g. retrieving verification data, introduced later).
Finally, add digest_cache_hash_key() to compute the hash table key from the
first two bytes of the digest (modulo the number of slots).
Signed-off-by: Roberto Sassu <[email protected]>
---
include/linux/digest_cache.h | 34 +++++
security/digest_cache/Kconfig | 11 ++
security/digest_cache/Makefile | 2 +-
security/digest_cache/htable.c | 250 +++++++++++++++++++++++++++++++
security/digest_cache/internal.h | 43 ++++++
security/digest_cache/main.c | 3 +
6 files changed, 342 insertions(+), 1 deletion(-)
create mode 100644 security/digest_cache/htable.c
diff --git a/include/linux/digest_cache.h b/include/linux/digest_cache.h
index e79f94a60b0f..4872700ac205 100644
--- a/include/linux/digest_cache.h
+++ b/include/linux/digest_cache.h
@@ -11,12 +11,39 @@
#define _LINUX_DIGEST_CACHE_H
#include <linux/fs.h>
+#include <crypto/hash_info.h>
struct digest_cache;
+/**
+ * typedef digest_cache_found_t - Digest cache reference as numeric value
+ *
+ * This new type represents a digest cache reference that should not be put.
+ */
+typedef unsigned long digest_cache_found_t;
+
+/**
+ * digest_cache_from_found_t - Convert digest_cache_found_t to digest cache ptr
+ * @found: digest_cache_found_t value
+ *
+ * Convert the digest_cache_found_t returned by digest_cache_lookup() to a
+ * digest cache pointer, so that it can be passed to the other functions of the
+ * API.
+ *
+ * Return: Digest cache pointer.
+ */
+static inline struct digest_cache *
+digest_cache_from_found_t(digest_cache_found_t found)
+{
+ return (struct digest_cache *)found;
+}
+
#ifdef CONFIG_SECURITY_DIGEST_CACHE
struct digest_cache *digest_cache_get(struct dentry *dentry);
void digest_cache_put(struct digest_cache *digest_cache);
+digest_cache_found_t digest_cache_lookup(struct dentry *dentry,
+ struct digest_cache *digest_cache,
+ u8 *digest, enum hash_algo algo);
#else
static inline struct digest_cache *digest_cache_get(struct dentry *dentry)
@@ -28,5 +55,12 @@ static inline void digest_cache_put(struct digest_cache *digest_cache)
{
}
+static inline digest_cache_found_t
+digest_cache_lookup(struct dentry *dentry, struct digest_cache *digest_cache,
+ u8 *digest, enum hash_algo algo)
+{
+ return 0UL;
+}
+
#endif /* CONFIG_SECURITY_DIGEST_CACHE */
#endif /* _LINUX_DIGEST_CACHE_H */
diff --git a/security/digest_cache/Kconfig b/security/digest_cache/Kconfig
index 2f361c7844df..c7e77cf2c173 100644
--- a/security/digest_cache/Kconfig
+++ b/security/digest_cache/Kconfig
@@ -19,3 +19,14 @@ config DIGEST_LIST_DEFAULT_PATH
It can be changed at run-time, by writing the new path to the
securityfs interface. Digest caches created with the old path are
not affected by the change.
+
+config DIGEST_CACHE_HTABLE_DEPTH
+ int
+ default 30
+ help
+ Desired average depth of the collision list in the digest cache
+ hash tables.
+
+ A smaller number will increase the amount of hash table slots, and
+ make the search faster. A bigger number will decrease the number of
+ hash table slots, but make the search slower.
diff --git a/security/digest_cache/Makefile b/security/digest_cache/Makefile
index 1330655e33b1..7e00c53d8f55 100644
--- a/security/digest_cache/Makefile
+++ b/security/digest_cache/Makefile
@@ -4,4 +4,4 @@
obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache.o
-digest_cache-y := main.o secfs.o
+digest_cache-y := main.o secfs.o htable.o
diff --git a/security/digest_cache/htable.c b/security/digest_cache/htable.c
new file mode 100644
index 000000000000..d2d5d8f5e5b1
--- /dev/null
+++ b/security/digest_cache/htable.c
@@ -0,0 +1,250 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Implement hash table operations for the digest cache.
+ */
+
+#define pr_fmt(fmt) "DIGEST CACHE: "fmt
+#include "internal.h"
+
+/**
+ * digest_cache_hash_key - Compute hash key
+ * @digest: Digest cache
+ * @num_slots: Number of slots in the hash table
+ *
+ * This function computes a hash key based on the first two bytes of the
+ * digest and the number of slots of the hash table.
+ *
+ * Return: Hash key.
+ */
+static inline unsigned int digest_cache_hash_key(u8 *digest,
+ unsigned int num_slots)
+{
+ /* Same as ima_hash_key() but parametrized. */
+ return (digest[0] | digest[1] << 8) % num_slots;
+}
+
+/**
+ * lookup_htable - Lookup a hash table
+ * @digest_cache: Digest cache
+ * @algo: Algorithm of the desired hash table
+ *
+ * This function searches the hash table for a given algorithm in the digest
+ * cache.
+ *
+ * Return: A hash table if found, NULL otherwise.
+ */
+static struct htable *lookup_htable(struct digest_cache *digest_cache,
+ enum hash_algo algo)
+{
+ struct htable *h;
+
+ list_for_each_entry(h, &digest_cache->htables, next)
+ if (h->algo == algo)
+ return h;
+
+ return NULL;
+}
+
+/**
+ * digest_cache_htable_init - Allocate and initialize the hash table
+ * @digest_cache: Digest cache
+ * @num_digests: Number of digests to add to the digest cache
+ * @algo: Algorithm of the digests
+ *
+ * This function allocates and initializes the hash table for a given algorithm.
+ * The number of slots depends on the number of digests to add to the digest
+ * cache, and the constant CONFIG_DIGEST_CACHE_HTABLE_DEPTH stating the desired
+ * average depth of the collision list.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_htable_init(struct digest_cache *digest_cache, u64 num_digests,
+ enum hash_algo algo)
+{
+ struct htable *h;
+ int i;
+
+ h = lookup_htable(digest_cache, algo);
+ if (h)
+ return 0;
+
+ h = kmalloc(sizeof(*h), GFP_KERNEL);
+ if (!h)
+ return -ENOMEM;
+
+ h->num_slots = DIV_ROUND_UP(num_digests,
+ CONFIG_DIGEST_CACHE_HTABLE_DEPTH);
+ h->slots = kmalloc_array(h->num_slots, sizeof(*h->slots), GFP_KERNEL);
+ if (!h->slots) {
+ kfree(h);
+ return -ENOMEM;
+ }
+
+ for (i = 0; i < h->num_slots; i++)
+ INIT_HLIST_HEAD(&h->slots[i]);
+
+ h->num_digests = 0;
+ h->algo = algo;
+
+ list_add_tail(&h->next, &digest_cache->htables);
+
+ pr_debug("Initialized hash table for digest list %s, digests: %llu, slots: %u, algo: %s\n",
+ digest_cache->path_str, num_digests, h->num_slots,
+ hash_algo_name[algo]);
+ return 0;
+}
+
+/**
+ * digest_cache_htable_add - Add a new digest to the digest cache
+ * @digest_cache: Digest cache
+ * @digest: Digest to add
+ * @algo: Algorithm of digest
+ *
+ * This function, invoked by a digest list parser, adds a digest extracted
+ * from a digest list to the digest cache.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_htable_add(struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo)
+{
+ struct htable *h;
+ struct digest_cache_entry *entry;
+ unsigned int key;
+ int digest_len;
+
+ h = lookup_htable(digest_cache, algo);
+ if (!h) {
+ pr_debug("No hash table for algorithm %s was found in digest cache %s, initialize one\n",
+ hash_algo_name[algo], digest_cache->path_str);
+ return -ENOENT;
+ }
+
+ digest_len = hash_digest_size[algo];
+
+ entry = kmalloc(sizeof(*entry) + digest_len, GFP_KERNEL);
+ if (!entry)
+ return -ENOMEM;
+
+ memcpy(entry->digest, digest, digest_len);
+
+ key = digest_cache_hash_key(digest, h->num_slots);
+ hlist_add_head(&entry->hnext, &h->slots[key]);
+ h->num_digests++;
+ pr_debug("Added digest %s:%*phN to digest cache %s, num of %s digests: %llu\n",
+ hash_algo_name[algo], digest_len, digest,
+ digest_cache->path_str, hash_algo_name[algo], h->num_digests);
+ return 0;
+}
+
+/**
+ * digest_cache_htable_lookup - Search a digest in the digest cache
+ * @dentry: Dentry of the file whose digest is looked up
+ * @digest_cache: Digest cache
+ * @digest: Digest to search
+ * @algo: Algorithm of the digest to search
+ *
+ * This function searches the passed digest and algorithm in the passed digest
+ * cache.
+ *
+ * Return: Zero if the digest is found, -ENOENT if not.
+ */
+int digest_cache_htable_lookup(struct dentry *dentry,
+ struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo)
+{
+ struct digest_cache_entry *entry;
+ struct htable *h;
+ unsigned int key;
+ int digest_len;
+ int search_depth = 0;
+
+ h = lookup_htable(digest_cache, algo);
+ if (!h)
+ return -ENOENT;
+
+ digest_len = hash_digest_size[algo];
+ key = digest_cache_hash_key(digest, h->num_slots);
+
+ hlist_for_each_entry(entry, &h->slots[key], hnext) {
+ if (!memcmp(entry->digest, digest, digest_len)) {
+ pr_debug("Cache hit at depth %d for file %s, digest %s:%*phN in digest cache %s\n",
+ search_depth, dentry->d_name.name,
+ hash_algo_name[algo], digest_len, digest,
+ digest_cache->path_str);
+
+ return 0;
+ }
+
+ search_depth++;
+ }
+
+ pr_debug("Cache miss for file %s, digest %s:%*phN in digest cache %s\n",
+ dentry->d_name.name, hash_algo_name[algo], digest_len, digest,
+ digest_cache->path_str);
+ return -ENOENT;
+}
+
+/**
+ * digest_cache_lookup - Search a digest in the digest cache
+ * @dentry: Dentry of the file whose digest is looked up
+ * @digest_cache: Digest cache
+ * @digest: Digest to search
+ * @algo: Algorithm of the digest to search
+ *
+ * This function calls digest_cache_htable_lookup() to search a digest in the
+ * passed digest cache, obtained with digest_cache_get().
+ *
+ * It returns the digest cache reference as the digest_cache_found_t type, to
+ * avoid that the digest cache is accidentally put. The digest_cache_found_t
+ * type can be converted back to a digest cache pointer, by
+ * calling digest_cache_from_found_t().
+ *
+ * Return: A positive digest_cache_found_t if the digest is found, zero if not.
+ */
+digest_cache_found_t digest_cache_lookup(struct dentry *dentry,
+ struct digest_cache *digest_cache,
+ u8 *digest, enum hash_algo algo)
+{
+ int ret;
+
+ ret = digest_cache_htable_lookup(dentry, digest_cache, digest, algo);
+ return (!ret) ? (digest_cache_found_t)digest_cache : 0UL;
+}
+EXPORT_SYMBOL_GPL(digest_cache_lookup);
+
+/**
+ * digest_cache_htable_free - Free the hash tables
+ * @digest_cache: Digest cache
+ *
+ * This function removes all digests from all hash tables in the digest cache,
+ * and frees the memory.
+ */
+void digest_cache_htable_free(struct digest_cache *digest_cache)
+{
+ struct htable *h, *h_tmp;
+ struct digest_cache_entry *p;
+ struct hlist_node *q;
+ int i;
+
+ list_for_each_entry_safe(h, h_tmp, &digest_cache->htables, next) {
+ for (i = 0; i < h->num_slots; i++) {
+ hlist_for_each_entry_safe(p, q, &h->slots[i], hnext) {
+ hlist_del(&p->hnext);
+ pr_debug("Removed digest %s:%*phN from digest cache %s\n",
+ hash_algo_name[h->algo],
+ hash_digest_size[h->algo], p->digest,
+ digest_cache->path_str);
+ kfree(p);
+ }
+ }
+
+ list_del(&h->next);
+ kfree(h->slots);
+ kfree(h);
+ }
+}
diff --git a/security/digest_cache/internal.h b/security/digest_cache/internal.h
index bbf5eefe5c82..ee6487acce1d 100644
--- a/security/digest_cache/internal.h
+++ b/security/digest_cache/internal.h
@@ -16,8 +16,40 @@
/* Digest cache bits in flags. */
#define INIT_IN_PROGRESS 0 /* Digest cache being initialized. */
+/**
+ * struct digest_cache_entry - Entry of a digest cache hash table
+ * @hnext: Pointer to the next element in the collision list
+ * @digest: Stored digest
+ *
+ * This structure represents an entry of a digest cache hash table, storing a
+ * digest.
+ */
+struct digest_cache_entry {
+ struct hlist_node hnext;
+ u8 digest[];
+} __packed;
+
+/**
+ * struct htable - Hash table
+ * @next: Next hash table in the linked list
+ * @slots: Hash table slots
+ * @num_slots: Number of slots
+ * @num_digests: Number of digests stored in the hash table
+ * @algo: Algorithm of the digests
+ *
+ * This structure is a hash table storing digests of file content or metadata.
+ */
+struct htable {
+ struct list_head next;
+ struct hlist_head *slots;
+ unsigned int num_slots;
+ u64 num_digests;
+ enum hash_algo algo;
+};
+
/**
* struct digest_cache - Digest cache
+ * @htables: Hash tables (one per algorithm)
* @ref_count: Number of references to the digest cache
* @path_str: Path of the digest list the digest cache was created from
* @flags: Control flags
@@ -25,6 +57,7 @@
* This structure represents a cache of digests extracted from a digest list.
*/
struct digest_cache {
+ struct list_head htables;
atomic_t ref_count;
char *path_str;
unsigned long flags;
@@ -84,4 +117,14 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
struct path *digest_list_path,
char *path_str, char *filename);
+/* htable.c */
+int digest_cache_htable_init(struct digest_cache *digest_cache, u64 num_digests,
+ enum hash_algo algo);
+int digest_cache_htable_add(struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo);
+int digest_cache_htable_lookup(struct dentry *dentry,
+ struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo);
+void digest_cache_htable_free(struct digest_cache *digest_cache);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/digest_cache/main.c b/security/digest_cache/main.c
index 8bae2e91ac4c..fa435b6566fa 100644
--- a/security/digest_cache/main.c
+++ b/security/digest_cache/main.c
@@ -48,6 +48,7 @@ static struct digest_cache *digest_cache_alloc_init(char *path_str,
atomic_set(&digest_cache->ref_count, 1);
digest_cache->flags = 0UL;
+ INIT_LIST_HEAD(&digest_cache->htables);
pr_debug("New digest cache %s (ref count: %d)\n",
digest_cache->path_str, atomic_read(&digest_cache->ref_count));
@@ -63,6 +64,8 @@ static struct digest_cache *digest_cache_alloc_init(char *path_str,
*/
static void digest_cache_free(struct digest_cache *digest_cache)
{
+ digest_cache_htable_free(digest_cache);
+
pr_debug("Freed digest cache %s\n", digest_cache->path_str);
kfree(digest_cache->path_str);
kmem_cache_free(digest_cache_cache, digest_cache);
--
2.34.1
From: Roberto Sassu <[email protected]>
Introduce digest_cache_populate() to populate the digest cache from a
digest list.
It opens the file and then schedules a work to read the content (with new
file type READING_DIGEST_LIST). Scheduling a work solves the problem of
kernel_read_file() returning -EINTR.
Once the work is done, this function calls digest_cache_strip_modsig() to
strip a module-style appended signature, if present, and finally calls
digest_cache_parse_digest_list() to parse the data.
The latter function, which at the moment does nothing, will be completed
with calls to parsing functions selected from the digest list file name.
It expects digest lists file names to be in the format:
[<seq num>-]<digest list format>-<digest list name>
<seq-num>- is an optional prefix to impose in which order digest lists in
a directory should be parsed.
Failing to populate a digest cache causes it to be marked as invalid and to
not be returned by digest_cache_create(). Dig_owner however is kept, to
avoid an excessive number of retries, which would probably not succeed
either.
Signed-off-by: Roberto Sassu <[email protected]>
---
include/linux/kernel_read_file.h | 1 +
security/digest_cache/Makefile | 2 +-
security/digest_cache/internal.h | 26 ++++++
security/digest_cache/main.c | 18 ++++
security/digest_cache/modsig.c | 66 ++++++++++++++
security/digest_cache/populate.c | 149 +++++++++++++++++++++++++++++++
6 files changed, 261 insertions(+), 1 deletion(-)
create mode 100644 security/digest_cache/modsig.c
create mode 100644 security/digest_cache/populate.c
diff --git a/include/linux/kernel_read_file.h b/include/linux/kernel_read_file.h
index 90451e2e12bd..85f602e49e2f 100644
--- a/include/linux/kernel_read_file.h
+++ b/include/linux/kernel_read_file.h
@@ -14,6 +14,7 @@
id(KEXEC_INITRAMFS, kexec-initramfs) \
id(POLICY, security-policy) \
id(X509_CERTIFICATE, x509-certificate) \
+ id(DIGEST_LIST, digest-list) \
id(MAX_ID, )
#define __fid_enumify(ENUM, dummy) READING_ ## ENUM,
diff --git a/security/digest_cache/Makefile b/security/digest_cache/Makefile
index 7e00c53d8f55..c1452437d02f 100644
--- a/security/digest_cache/Makefile
+++ b/security/digest_cache/Makefile
@@ -4,4 +4,4 @@
obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache.o
-digest_cache-y := main.o secfs.o htable.o
+digest_cache-y := main.o secfs.o htable.o populate.o modsig.o
diff --git a/security/digest_cache/internal.h b/security/digest_cache/internal.h
index ee6487acce1d..0d9c01dd9bc8 100644
--- a/security/digest_cache/internal.h
+++ b/security/digest_cache/internal.h
@@ -15,6 +15,24 @@
/* Digest cache bits in flags. */
#define INIT_IN_PROGRESS 0 /* Digest cache being initialized. */
+#define INVALID 1 /* Digest cache marked as invalid. */
+
+/**
+ * struct read_work - Structure to schedule reading a digest list
+ * @work: Work structure
+ * @file: File descriptor of the digest list to read
+ * @data: Digest list data (updated)
+ * @ret: Return value from kernel_read_file() (updated)
+ *
+ * This structure contains the necessary information to schedule reading a
+ * digest list.
+ */
+struct read_work {
+ struct work_struct work;
+ struct file *file;
+ void *data;
+ int ret;
+};
/**
* struct digest_cache_entry - Entry of a digest cache hash table
@@ -127,4 +145,12 @@ int digest_cache_htable_lookup(struct dentry *dentry,
enum hash_algo algo);
void digest_cache_htable_free(struct digest_cache *digest_cache);
+/* populate.c */
+int digest_cache_populate(struct digest_cache *digest_cache,
+ struct path *digest_list_path, char *path_str,
+ char *filename);
+
+/* modsig.c */
+size_t digest_cache_strip_modsig(__u8 *data, size_t data_len);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/digest_cache/main.c b/security/digest_cache/main.c
index fa435b6566fa..8e9ab99081c3 100644
--- a/security/digest_cache/main.c
+++ b/security/digest_cache/main.c
@@ -166,6 +166,17 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
set_bit(INIT_IN_PROGRESS, &dig_sec->dig_owner->flags);
mutex_unlock(&dig_sec->dig_owner_mutex);
+ if (S_ISREG(inode->i_mode)) {
+ ret = digest_cache_populate(digest_cache, digest_list_path,
+ path_str, filename);
+ if (ret < 0) {
+ pr_debug("Failed to populate digest cache %s ret: %d (keep digest cache)\n",
+ digest_cache->path_str, ret);
+ /* Prevent usage of partially-populated digest cache. */
+ set_bit(INVALID, &digest_cache->flags);
+ }
+ }
+
/* Creation complete, notify the other lock contenders. */
clear_and_wake_up_bit(INIT_IN_PROGRESS, &dig_sec->dig_owner->flags);
exists:
@@ -173,6 +184,13 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
/* Wait until creation complete. */
wait_on_bit(&dig_sec->dig_owner->flags, INIT_IN_PROGRESS,
TASK_UNINTERRUPTIBLE);
+
+ if (test_bit(INVALID, &digest_cache->flags)) {
+ pr_debug("Digest cache %s is invalid, don't return it\n",
+ digest_cache->path_str);
+ digest_cache_put(digest_cache);
+ digest_cache = NULL;
+ }
out:
if (digest_list_path == &file_path)
path_put(&file_path);
diff --git a/security/digest_cache/modsig.c b/security/digest_cache/modsig.c
new file mode 100644
index 000000000000..3bdda00d8bb2
--- /dev/null
+++ b/security/digest_cache/modsig.c
@@ -0,0 +1,66 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
+ * Copyright (C) 2019 IBM Corporation
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Strip module-style appended signatures.
+ */
+
+#define pr_fmt(fmt) "DIGEST CACHE: "fmt
+#include <linux/module.h>
+#include <linux/module_signature.h>
+
+#include "internal.h"
+
+/**
+ * digest_cache_strip_modsig - Strip module-style appended sig from digest list
+ * @data: Data to parse
+ * @data_len: Length of @data
+ *
+ * This function strips the module-style appended signature from a digest list,
+ * if present.
+ *
+ * Return: Size of stripped data on success, original size otherwise.
+ */
+size_t digest_cache_strip_modsig(__u8 *data, size_t data_len)
+{
+ const size_t marker_len = strlen(MODULE_SIG_STRING);
+ const struct module_signature *sig;
+ size_t parsed_data_len = data_len;
+ size_t sig_len;
+ const void *p;
+
+ /* From ima_modsig.c */
+ if (data_len <= marker_len + sizeof(*sig))
+ return data_len;
+
+ p = data + parsed_data_len - marker_len;
+ if (memcmp(p, MODULE_SIG_STRING, marker_len))
+ return data_len;
+
+ parsed_data_len -= marker_len;
+ sig = (const struct module_signature *)(p - sizeof(*sig));
+
+ /* From module_signature.c */
+ if (be32_to_cpu(sig->sig_len) >= parsed_data_len - sizeof(*sig))
+ return data_len;
+
+ /* Unlike for module signatures, accept all signature types. */
+ if (sig->algo != 0 ||
+ sig->hash != 0 ||
+ sig->signer_len != 0 ||
+ sig->key_id_len != 0 ||
+ sig->__pad[0] != 0 ||
+ sig->__pad[1] != 0 ||
+ sig->__pad[2] != 0) {
+ pr_debug("Signature info has unexpected non-zero params\n");
+ return data_len;
+ }
+
+ sig_len = be32_to_cpu(sig->sig_len);
+ parsed_data_len -= sig_len + sizeof(*sig);
+ return parsed_data_len;
+}
diff --git a/security/digest_cache/populate.c b/security/digest_cache/populate.c
new file mode 100644
index 000000000000..415e638f587b
--- /dev/null
+++ b/security/digest_cache/populate.c
@@ -0,0 +1,149 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Implement the code to populate a digest cache.
+ */
+
+#define pr_fmt(fmt) "DIGEST CACHE: "fmt
+#include <linux/init_task.h>
+#include <linux/kernel_read_file.h>
+
+#include "internal.h"
+
+/**
+ * digest_cache_parse_digest_list - Parse a digest list
+ * @digest_cache: Digest cache
+ * @path_str: Path string of the digest list
+ * @filename: Digest list file name (can be an empty string)
+ * @data: Data to parse
+ * @data_len: Length of @data
+ *
+ * This function selects a parser for a digest list depending on its file name,
+ * and calls the appropriate parsing function. It expects the file name to be
+ * in the format: [<seq num>-]<format>-<digest list name>. <seq num> is
+ * optional.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int digest_cache_parse_digest_list(struct digest_cache *digest_cache,
+ char *path_str, char *filename,
+ void *data, size_t data_len)
+{
+ char *format, *next_sep;
+ int ret = -EINVAL;
+
+ if (!filename[0]) {
+ filename = strrchr(path_str, '/');
+ if (!filename)
+ return ret;
+
+ filename++;
+ }
+
+ format = filename;
+
+ /*
+ * Since we expect that all files start with a digest list format, this
+ * check is reliable to detect <seq num>.
+ */
+ if (filename[0] >= '0' && filename[0] <= '9') {
+ format = strchr(filename, '-');
+ if (!format)
+ return ret;
+
+ format++;
+ }
+
+ next_sep = strchr(format, '-');
+ if (!next_sep)
+ return ret;
+
+ pr_debug("Parsing %s%s%s, format: %.*s, size: %ld\n", path_str,
+ filename[0] ? "/" : "", filename, (int)(next_sep - format),
+ format, data_len);
+
+ return ret;
+}
+
+/**
+ * digest_cache_read_digest_list - Read a digest list
+ * @work: Work structure
+ *
+ * This function is invoked by schedule_work() to read a digest list.
+ *
+ * It does not return a value, but stores the result in the passed structure.
+ */
+static void digest_cache_read_digest_list(struct work_struct *work)
+{
+ struct read_work *w = container_of(work, struct read_work, work);
+
+ w->ret = kernel_read_file(w->file, 0, &w->data, INT_MAX, NULL,
+ READING_DIGEST_LIST);
+}
+
+/**
+ * digest_cache_populate - Populate a digest cache from a digest list
+ * @digest_cache: Digest cache
+ * @digest_list_path: Path structure of the digest list
+ * @path_str: Path string of the digest list
+ * @filename: Digest list file name (can be an empty string)
+ *
+ * This function opens the digest list for reading it. Then, it schedules a
+ * work to read the digest list and, once the work is done, it calls
+ * digest_cache_strip_modsig() to strip a module-style appended signature and
+ * digest_cache_parse_digest_list() for extracting and adding digests to the
+ * digest cache.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_populate(struct digest_cache *digest_cache,
+ struct path *digest_list_path, char *path_str,
+ char *filename)
+{
+ struct file *file;
+ void *data;
+ size_t data_len;
+ struct read_work w;
+ int ret;
+
+ file = dentry_open(digest_list_path, O_RDONLY, &init_cred);
+ if (IS_ERR(file)) {
+ pr_debug("Unable to open digest list %s%s%s, ret: %ld\n",
+ path_str, filename[0] ? "/" : "", filename,
+ PTR_ERR(file));
+ return PTR_ERR(file);
+ }
+
+ w.data = NULL;
+ w.file = file;
+ INIT_WORK_ONSTACK(&w.work, digest_cache_read_digest_list);
+
+ schedule_work(&w.work);
+ flush_work(&w.work);
+ destroy_work_on_stack(&w.work);
+ fput(file);
+
+ ret = w.ret;
+ data = w.data;
+
+ if (ret < 0) {
+ pr_debug("Unable to read digest list %s%s%s, ret: %d\n",
+ path_str, filename[0] ? "/" : "", filename, ret);
+ return ret;
+ }
+
+ data_len = digest_cache_strip_modsig(data, ret);
+
+ /* Digest list parsers initialize the hash table and add the digests. */
+ ret = digest_cache_parse_digest_list(digest_cache, path_str, filename,
+ data, data_len);
+ if (ret < 0)
+ pr_debug("Error parsing digest list %s%s%s, ret: %d\n",
+ path_str, filename[0] ? "/" : "", filename, ret);
+
+ vfree(data);
+ return ret;
+}
--
2.34.1
From: Roberto Sassu <[email protected]>
Add digest_list_parse_tlv(), to parse TLV-formatted (Type Length Value)
digest lists. Their structure is:
[header: DIGEST_LIST_FILE, num fields, total len]
[field: DIGEST_LIST_ALGO, length, value]
[field: DIGEST_LIST_ENTRY#1, length, value (below)]
|- [header: DIGEST_LIST_ENTRY_DATA, num fields, total len]
|- [DIGEST_LIST_ENTRY_DIGEST#1, length, file digest]
|- [DIGEST_LIST_ENTRY_PATH#1, length, file path]
[field: DIGEST_LIST_ENTRY#N, length, value (below)]
|- [header: DIGEST_LIST_ENTRY_DATA, num fields, total len]
|- [DIGEST_LIST_ENTRY_DIGEST#N, length, file digest]
|- [DIGEST_LIST_ENTRY_PATH#N, length, file path]
DIGEST_LIST_ALGO must have a fixed length of sizeof(u64).
The data of the DIGEST_LIST_ENTRY field are itself in TLV format.
Currently defined fields are sufficient for measurement/appraisal of file
content. More fields will be introduced later for file metadata.
Introduce digest_list_file_callback() to handle the DIGEST_LIST_FILE
fields, DIGEST_LIST_ALGO and DIGEST_LIST_ENTRY, and the respective field
parsers parse_digest_list_algo() and parse_digest_list_entry().
Also introduce digest_list_entry_data_callback(), to handle the
DIGEST_LIST_ENTRY_DATA (nested) fields, DIGEST_LIST_ENTRY_DIGEST and
DIGEST_LIST_ENTRY_PATH, and the respective field parsers
parse_digest_list_entry_digest() and parse_digest_list_entry_path().
The TLV parser itself is defined in lib/tlv_parser.c.
Both the TLV parser and the tlv digest list parser have been formally
verified with Frama-C (https://frama-c.com/).
The analysis has been done on this file:
https://github.com/robertosassu/rpm-formal/blob/main/validate_tlv.c
Here is the result of the analysis:
[eva:summary] ====== ANALYSIS SUMMARY ======
---------------------------------------------------------------------------
13 functions analyzed (out of 13): 100% coverage.
In these functions, 240 statements reached (out of 254): 94% coverage.
---------------------------------------------------------------------------
Some errors and warnings have been raised during the analysis:
by the Eva analyzer: 0 errors 4 warnings
by the Frama-C kernel: 0 errors 0 warnings
---------------------------------------------------------------------------
0 alarms generated by the analysis.
---------------------------------------------------------------------------
Evaluation of the logical properties reached by the analysis:
Assertions 5 valid 0 unknown 0 invalid 5 total
Preconditions 24 valid 0 unknown 0 invalid 24 total
100% of the logical properties reached have been proven.
---------------------------------------------------------------------------
The warnings are:
[eva] validate_tlv.c:437: Warning:
this partitioning parameter cannot be evaluated safely on all states
[eva] validate_tlv.c:445: Warning:
this partitioning parameter cannot be evaluated safely on all states
[eva] validate_tlv.c:354: Warning:
this partitioning parameter cannot be evaluated safely on all states
[eva] validate_tlv.c:382: Warning:
this partitioning parameter cannot be evaluated safely on all states
Signed-off-by: Roberto Sassu <[email protected]>
---
include/uapi/linux/tlv_digest_list.h | 72 ++++++
security/digest_cache/Kconfig | 1 +
security/digest_cache/Makefile | 2 +
security/digest_cache/parsers/parsers.h | 13 ++
security/digest_cache/parsers/tlv.c | 299 ++++++++++++++++++++++++
security/digest_cache/populate.c | 4 +
6 files changed, 391 insertions(+)
create mode 100644 include/uapi/linux/tlv_digest_list.h
create mode 100644 security/digest_cache/parsers/parsers.h
create mode 100644 security/digest_cache/parsers/tlv.c
diff --git a/include/uapi/linux/tlv_digest_list.h b/include/uapi/linux/tlv_digest_list.h
new file mode 100644
index 000000000000..8c97a46901c1
--- /dev/null
+++ b/include/uapi/linux/tlv_digest_list.h
@@ -0,0 +1,72 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copyright (C) 2017-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Export definitions of the tlv digest list.
+ */
+
+#ifndef _UAPI_LINUX_TLV_DIGEST_LIST_H
+#define _UAPI_LINUX_TLV_DIGEST_LIST_H
+
+#include <linux/types.h>
+
+#define FOR_EACH_DIGEST_LIST_TYPE(DIGEST_LIST_TYPE) \
+ DIGEST_LIST_TYPE(DIGEST_LIST_FILE) \
+ DIGEST_LIST_TYPE(DIGEST_LIST__LAST)
+
+#define FOR_EACH_DIGEST_LIST_FIELD(DIGEST_LIST_FIELD) \
+ DIGEST_LIST_FIELD(DIGEST_LIST_ALGO) \
+ DIGEST_LIST_FIELD(DIGEST_LIST_ENTRY) \
+ DIGEST_LIST_FIELD(DIGEST_LIST_FIELD__LAST)
+
+#define FOR_EACH_DIGEST_LIST_ENTRY_TYPE(DIGEST_LIST_ENTRY_TYPE) \
+ DIGEST_LIST_ENTRY_TYPE(DIGEST_LIST_ENTRY_DATA) \
+ DIGEST_LIST_ENTRY_TYPE(DIGEST_LIST_ENTRY__LAST)
+
+#define FOR_EACH_DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_FIELD) \
+ DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_DIGEST) \
+ DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_PATH) \
+ DIGEST_LIST_ENTRY_FIELD(DIGEST_LIST_ENTRY_FIELD__LAST)
+
+#define GENERATE_ENUM(ENUM) ENUM,
+#define GENERATE_STRING(STRING) #STRING,
+
+/**
+ * enum digest_list_types - Types of digest list
+ *
+ * Enumerates the types of digest list to parse.
+ */
+enum digest_list_types {
+ FOR_EACH_DIGEST_LIST_TYPE(GENERATE_ENUM)
+};
+
+/**
+ * enum digest_list_fields - Digest list fields
+ *
+ * Enumerates the digest list fields.
+ */
+enum digest_list_fields {
+ FOR_EACH_DIGEST_LIST_FIELD(GENERATE_ENUM)
+};
+
+/**
+ * enum digest_list_entry_types - Types of data stored in DIGEST_LIST_ENTRY
+ *
+ * Enumerates the types of data stored in DIGEST_LIST_ENTRY (nested TLV data).
+ */
+enum digest_list_entry_types {
+ FOR_EACH_DIGEST_LIST_ENTRY_TYPE(GENERATE_ENUM)
+};
+
+/**
+ * enum digest_list_entry_fields - DIGEST_LIST_ENTRY fields
+ *
+ * Enumerates the DIGEST_LIST_ENTRY fields.
+ */
+enum digest_list_entry_fields {
+ FOR_EACH_DIGEST_LIST_ENTRY_FIELD(GENERATE_ENUM)
+};
+
+#endif /* _UAPI_LINUX_TLV_DIGEST_LIST_H */
diff --git a/security/digest_cache/Kconfig b/security/digest_cache/Kconfig
index c7e77cf2c173..dc9ed8f0f883 100644
--- a/security/digest_cache/Kconfig
+++ b/security/digest_cache/Kconfig
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0
config SECURITY_DIGEST_CACHE
bool "Digest_cache LSM"
+ select TLV_PARSER
default n
help
This option enables an LSM maintaining a cache of digests
diff --git a/security/digest_cache/Makefile b/security/digest_cache/Makefile
index c1452437d02f..a383b6ef2550 100644
--- a/security/digest_cache/Makefile
+++ b/security/digest_cache/Makefile
@@ -5,3 +5,5 @@
obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache.o
digest_cache-y := main.o secfs.o htable.o populate.o modsig.o
+
+digest_cache-y += parsers/tlv.o
diff --git a/security/digest_cache/parsers/parsers.h b/security/digest_cache/parsers/parsers.h
new file mode 100644
index 000000000000..1bbae426ab9f
--- /dev/null
+++ b/security/digest_cache/parsers/parsers.h
@@ -0,0 +1,13 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Digest list parsers.
+ */
+
+#include "../internal.h"
+
+int digest_list_parse_tlv(struct digest_cache *digest_cache, const u8 *data,
+ size_t data_len);
diff --git a/security/digest_cache/parsers/tlv.c b/security/digest_cache/parsers/tlv.c
new file mode 100644
index 000000000000..97e2c36b93a8
--- /dev/null
+++ b/security/digest_cache/parsers/tlv.c
@@ -0,0 +1,299 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Parse a tlv digest list.
+ */
+
+#define pr_fmt(fmt) "TLV DIGEST LIST: "fmt
+#include <linux/tlv_parser.h>
+#include <uapi/linux/tlv_digest_list.h>
+
+#include "parsers.h"
+
+#define kenter(FMT, ...) \
+ pr_debug("==> %s(" FMT ")\n", __func__, ##__VA_ARGS__)
+#define kleave(FMT, ...) \
+ pr_debug("<== %s()" FMT "\n", __func__, ##__VA_ARGS__)
+
+const char *digest_list_types_str[] = {
+ FOR_EACH_DIGEST_LIST_TYPE(GENERATE_STRING)
+};
+
+const char *digest_list_fields_str[] = {
+ FOR_EACH_DIGEST_LIST_FIELD(GENERATE_STRING)
+};
+
+const char *digest_list_entry_types_str[] = {
+ FOR_EACH_DIGEST_LIST_ENTRY_TYPE(GENERATE_STRING)
+};
+
+const char *digest_list_entry_fields_str[] = {
+ FOR_EACH_DIGEST_LIST_ENTRY_FIELD(GENERATE_STRING)
+};
+
+struct tlv_callback_data {
+ struct digest_cache *digest_cache;
+ u64 parsed_data_type;
+ u64 parsed_num_entries;
+ u64 parsed_total_len;
+ enum hash_algo algo;
+};
+
+/**
+ * parse_digest_list_entry_digest - Parse DIGEST_LIST_ENTRY_DIGEST field
+ * @tlv_data: Parser callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This function parses the DIGEST_LIST_ENTRY_DIGEST field (file digest).
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int parse_digest_list_entry_digest(struct tlv_callback_data *tlv_data,
+ enum digest_list_entry_fields field,
+ const u8 *field_data,
+ u64 field_data_len)
+{
+ int ret;
+
+ kenter(",%u,%llu", field, field_data_len);
+
+ if (tlv_data->algo == HASH_ALGO__LAST) {
+ pr_debug("Digest algo not set\n");
+ ret = -EBADMSG;
+ goto out;
+ }
+
+ if (field_data_len != hash_digest_size[tlv_data->algo]) {
+ pr_debug("Unexpected data length %llu, expected %d\n",
+ field_data_len, hash_digest_size[tlv_data->algo]);
+ ret = -EBADMSG;
+ goto out;
+ }
+
+ ret = digest_cache_htable_add(tlv_data->digest_cache, (u8 *)field_data,
+ tlv_data->algo);
+out:
+ kleave(" = %d", ret);
+ return ret;
+}
+
+/**
+ * parse_digest_list_entry_path - Parse DIGEST_LIST_ENTRY_PATH field
+ * @tlv_data: Parser callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This function handles the DIGEST_LIST_ENTRY_PATH field (file path). It
+ * currently does not parse the data.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int parse_digest_list_entry_path(struct tlv_callback_data *tlv_data,
+ enum digest_list_entry_fields field,
+ const u8 *field_data,
+ u64 field_data_len)
+{
+ kenter(",%u,%llu", field, field_data_len);
+
+ kleave(" = 0");
+ return 0;
+}
+
+/**
+ * digest_list_entry_data_callback - DIGEST_LIST_ENTRY_DATA callback
+ * @callback_data: Callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This callback handles the fields of DIGEST_LIST_ENTRY_DATA (nested) data,
+ * and calls the appropriate parser.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int digest_list_entry_data_callback(void *callback_data, u64 field,
+ const u8 *field_data,
+ u64 field_data_len)
+{
+ struct tlv_callback_data *tlv_data;
+ int ret;
+
+ tlv_data = (struct tlv_callback_data *)callback_data;
+
+ switch (field) {
+ case DIGEST_LIST_ENTRY_DIGEST:
+ ret = parse_digest_list_entry_digest(tlv_data, field,
+ field_data,
+ field_data_len);
+ break;
+ case DIGEST_LIST_ENTRY_PATH:
+ ret = parse_digest_list_entry_path(tlv_data, field, field_data,
+ field_data_len);
+ break;
+ default:
+ pr_debug("Unhandled field %s\n",
+ digest_list_entry_fields_str[field]);
+ /* Just ignore non-relevant fields. */
+ ret = 0;
+ break;
+ }
+
+ return ret;
+}
+
+/**
+ * parse_digest_list_algo - Parse DIGEST_LIST_ALGO field
+ * @tlv_data: Parser callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This function parses the DIGEST_LIST_ALGO field (digest algorithm).
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int parse_digest_list_algo(struct tlv_callback_data *tlv_data,
+ enum digest_list_fields field,
+ const u8 *field_data, u64 field_data_len)
+{
+ u64 algo;
+ int ret;
+
+ kenter(",%u,%llu", field, field_data_len);
+
+ if (field_data_len != sizeof(u64)) {
+ pr_debug("Unexpected data length %llu, expected %lu\n",
+ field_data_len, sizeof(u64));
+ ret = -EBADMSG;
+ goto out;
+ }
+
+ algo = __be64_to_cpu(*(u64 *)field_data);
+
+ if (algo >= HASH_ALGO__LAST) {
+ pr_debug("Unexpected digest algo %llu\n", algo);
+ ret = -EBADMSG;
+ goto out;
+ }
+
+ ret = digest_cache_htable_init(tlv_data->digest_cache,
+ tlv_data->parsed_num_entries, algo);
+ if (ret < 0)
+ goto out;
+
+ tlv_data->algo = algo;
+
+ pr_debug("Digest algo: %s\n", hash_algo_name[algo]);
+out:
+ kleave(" = %d", ret);
+ return ret;
+}
+
+/**
+ * parse_digest_list_entry - Parse DIGEST_LIST_ENTRY field
+ * @tlv_data: Parser callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This function parses the DIGEST_LIST_ENTRY field.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int parse_digest_list_entry(struct tlv_callback_data *tlv_data,
+ enum digest_list_fields field,
+ const u8 *field_data, u64 field_data_len)
+{
+ int ret;
+
+ kenter(",%u,%llu", field, field_data_len);
+
+ ret = tlv_parse(DIGEST_LIST_ENTRY_DATA, digest_list_entry_data_callback,
+ tlv_data, field_data, field_data_len,
+ digest_list_entry_types_str, DIGEST_LIST_ENTRY__LAST,
+ digest_list_entry_fields_str,
+ DIGEST_LIST_ENTRY_FIELD__LAST);
+
+ kleave(" = %d", ret);
+ return ret;
+}
+
+/**
+ * digest_list_file_callback - DIGEST_LIST_FILE callback
+ * @callback_data: Callback data
+ * @field: Field identifier
+ * @field_data: Field data
+ * @field_data_len: Length of @field_data
+ *
+ * This callback handles the fields of DIGEST_LIST_FILE data, and calls the
+ * appropriate parser.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+static int digest_list_file_callback(void *callback_data, u64 field,
+ const u8 *field_data, u64 field_data_len)
+{
+ struct tlv_callback_data *tlv_data;
+ int ret;
+
+ tlv_data = (struct tlv_callback_data *)callback_data;
+
+ switch (field) {
+ case DIGEST_LIST_ALGO:
+ ret = parse_digest_list_algo(tlv_data, field, field_data,
+ field_data_len);
+ break;
+ case DIGEST_LIST_ENTRY:
+ ret = parse_digest_list_entry(tlv_data, field, field_data,
+ field_data_len);
+ break;
+ default:
+ pr_debug("Unhandled field %s\n",
+ digest_list_fields_str[field]);
+ /* Just ignore non-relevant fields. */
+ ret = 0;
+ break;
+ }
+
+ return ret;
+}
+
+/**
+ * digest_list_parse_tlv - Parse a tlv digest list
+ * @digest_cache: Digest cache
+ * @data: Data to parse
+ * @data_len: Length of @data
+ *
+ * This function parses a tlv digest list.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_list_parse_tlv(struct digest_cache *digest_cache, const u8 *data,
+ size_t data_len)
+{
+ struct tlv_callback_data tlv_data = {
+ .digest_cache = digest_cache,
+ .algo = HASH_ALGO__LAST
+ };
+ int ret;
+
+ ret = tlv_parse_hdr(&data, &data_len, &tlv_data.parsed_data_type,
+ &tlv_data.parsed_num_entries,
+ &tlv_data.parsed_total_len,
+ digest_list_types_str, DIGEST_LIST__LAST);
+ if (ret < 0)
+ return ret;
+
+ if (tlv_data.parsed_data_type != DIGEST_LIST_FILE)
+ return 0;
+
+ return tlv_parse_data(digest_list_file_callback, &tlv_data,
+ tlv_data.parsed_num_entries, data, data_len,
+ digest_list_fields_str, DIGEST_LIST_FIELD__LAST);
+}
diff --git a/security/digest_cache/populate.c b/security/digest_cache/populate.c
index 415e638f587b..13645ec4bb2b 100644
--- a/security/digest_cache/populate.c
+++ b/security/digest_cache/populate.c
@@ -12,6 +12,7 @@
#include <linux/kernel_read_file.h>
#include "internal.h"
+#include "parsers/parsers.h"
/**
* digest_cache_parse_digest_list - Parse a digest list
@@ -65,6 +66,9 @@ static int digest_cache_parse_digest_list(struct digest_cache *digest_cache,
filename[0] ? "/" : "", filename, (int)(next_sep - format),
format, data_len);
+ if (!strncmp(format, "tlv-", 4))
+ ret = digest_list_parse_tlv(digest_cache, data, data_len);
+
return ret;
}
--
2.34.1
From: Roberto Sassu <[email protected]>
Implement a simple parser of RPM headers, that extracts the digest and the
algorithm of the packaged files from the RPMTAG_FILEDIGESTS and
RPMTAG_FILEDIGESTALGO section, and add them to the digest cache.
The rpm digest list parser has been verified with Frama-C
(https://frama-c.com/).
The analysis has been done on this file:
https://github.com/robertosassu/rpm-formal/blob/main/validate_rpm.c
Here is the result of the analysis:
[eva:summary] ====== ANALYSIS SUMMARY ======
---------------------------------------------------------------------------
7 functions analyzed (out of 7): 100% coverage.
In these functions, 228 statements reached (out of 246): 92% coverage.
---------------------------------------------------------------------------
No errors or warnings raised during the analysis.
---------------------------------------------------------------------------
0 alarms generated by the analysis.
---------------------------------------------------------------------------
Evaluation of the logical properties reached by the analysis:
Assertions 6 valid 0 unknown 0 invalid 6 total
Preconditions 29 valid 0 unknown 0 invalid 29 total
100% of the logical properties reached have been proven.
---------------------------------------------------------------------------
Signed-off-by: Roberto Sassu <[email protected]>
---
security/digest_cache/Makefile | 1 +
security/digest_cache/parsers/parsers.h | 2 +
security/digest_cache/parsers/rpm.c | 223 ++++++++++++++++++++++++
security/digest_cache/populate.c | 2 +
4 files changed, 228 insertions(+)
create mode 100644 security/digest_cache/parsers/rpm.c
diff --git a/security/digest_cache/Makefile b/security/digest_cache/Makefile
index a383b6ef2550..eca4076497e6 100644
--- a/security/digest_cache/Makefile
+++ b/security/digest_cache/Makefile
@@ -7,3 +7,4 @@ obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache.o
digest_cache-y := main.o secfs.o htable.o populate.o modsig.o
digest_cache-y += parsers/tlv.o
+digest_cache-y += parsers/rpm.o
diff --git a/security/digest_cache/parsers/parsers.h b/security/digest_cache/parsers/parsers.h
index 1bbae426ab9f..3f00d29ed92a 100644
--- a/security/digest_cache/parsers/parsers.h
+++ b/security/digest_cache/parsers/parsers.h
@@ -11,3 +11,5 @@
int digest_list_parse_tlv(struct digest_cache *digest_cache, const u8 *data,
size_t data_len);
+int digest_list_parse_rpm(struct digest_cache *digest_cache, const u8 *data,
+ size_t data_len);
diff --git a/security/digest_cache/parsers/rpm.c b/security/digest_cache/parsers/rpm.c
new file mode 100644
index 000000000000..6c7fe9c9121c
--- /dev/null
+++ b/security/digest_cache/parsers/rpm.c
@@ -0,0 +1,223 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2017-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Parse an rpm digest list (RPM package header).
+ */
+
+#define pr_fmt(fmt) "RPM DIGEST LIST: "fmt
+#include <linux/module.h>
+
+#include "parsers.h"
+
+#define RPMTAG_FILEDIGESTS 1035
+#define RPMTAG_FILEDIGESTALGO 5011
+
+#define RPM_INT32_TYPE 4
+#define RPM_STRING_ARRAY_TYPE 8
+
+struct rpm_hdr {
+ u32 magic;
+ u32 reserved;
+ u32 tags;
+ u32 datasize;
+} __packed;
+
+struct rpm_entryinfo {
+ s32 tag;
+ u32 type;
+ s32 offset;
+ u32 count;
+} __packed;
+
+enum pgp_algos {
+ DIGEST_ALGO_MD5 = 1,
+ DIGEST_ALGO_SHA1 = 2,
+ DIGEST_ALGO_RMD160 = 3,
+ /* 4, 5, 6, and 7 are reserved. */
+ DIGEST_ALGO_SHA256 = 8,
+ DIGEST_ALGO_SHA384 = 9,
+ DIGEST_ALGO_SHA512 = 10,
+ DIGEST_ALGO_SHA224 = 11,
+};
+
+static const enum hash_algo pgp_algo_mapping[DIGEST_ALGO_SHA224 + 1] = {
+ [DIGEST_ALGO_MD5] = HASH_ALGO_MD5,
+ [DIGEST_ALGO_SHA1] = HASH_ALGO_SHA1,
+ [DIGEST_ALGO_RMD160] = HASH_ALGO_RIPE_MD_160,
+ [4] = HASH_ALGO__LAST,
+ [5] = HASH_ALGO__LAST,
+ [6] = HASH_ALGO__LAST,
+ [7] = HASH_ALGO__LAST,
+ [DIGEST_ALGO_SHA256] = HASH_ALGO_SHA256,
+ [DIGEST_ALGO_SHA384] = HASH_ALGO_SHA384,
+ [DIGEST_ALGO_SHA512] = HASH_ALGO_SHA512,
+ [DIGEST_ALGO_SHA224] = HASH_ALGO_SHA224,
+};
+
+/**
+ * digest_list_parse_rpm - Parse an rpm digest list
+ * @digest_cache: Digest cache
+ * @data: Data to parse
+ * @data_len: Length of @data
+ *
+ * This function parses an rpm digest list.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_list_parse_rpm(struct digest_cache *digest_cache, const u8 *data,
+ size_t data_len)
+{
+ const unsigned char rpm_header_magic[8] = {
+ 0x8e, 0xad, 0xe8, 0x01, 0x00, 0x00, 0x00, 0x00
+ };
+ const struct rpm_hdr *hdr;
+ const struct rpm_entryinfo *entry;
+ u32 tags, max_tags, datasize;
+ u32 digests_count, max_digests_count;
+ u32 digests_offset, algo_offset;
+ u32 digest_len, pkg_pgp_algo, i;
+ bool algo_offset_set = false, digests_offset_set = false;
+ enum hash_algo pkg_kernel_algo = HASH_ALGO_MD5;
+ u8 rpm_digest[SHA512_DIGEST_SIZE];
+ int ret;
+
+ if (data_len < sizeof(*hdr)) {
+ pr_debug("Not enough data for RPM header, current %ld, expected: %ld\n",
+ data_len, sizeof(*hdr));
+ return -EINVAL;
+ }
+
+ if (memcmp(data, rpm_header_magic, sizeof(rpm_header_magic))) {
+ pr_debug("RPM header magic mismatch\n");
+ return -EINVAL;
+ }
+
+ hdr = (const struct rpm_hdr *)data;
+ data += sizeof(*hdr);
+ data_len -= sizeof(*hdr);
+
+ tags = __be32_to_cpu(hdr->tags);
+ max_tags = data_len / sizeof(*entry);
+
+ /* Finite termination on tags loop. */
+ if (tags > max_tags)
+ return -EINVAL;
+
+ datasize = __be32_to_cpu(hdr->datasize);
+ if (datasize != data_len - tags * sizeof(*entry))
+ return -EINVAL;
+
+ pr_debug("Scanning %d RPM header sections\n", tags);
+ for (i = 0; i < tags; i++) {
+ if (data_len < sizeof(*entry))
+ return -EINVAL;
+
+ entry = (const struct rpm_entryinfo *)data;
+ data += sizeof(*entry);
+ data_len -= sizeof(*entry);
+
+ switch (__be32_to_cpu(entry->tag)) {
+ case RPMTAG_FILEDIGESTS:
+ if (__be32_to_cpu(entry->type) != RPM_STRING_ARRAY_TYPE)
+ return -EINVAL;
+
+ digests_offset = __be32_to_cpu(entry->offset);
+ digests_count = __be32_to_cpu(entry->count);
+ digests_offset_set = true;
+
+ pr_debug("Found RPMTAG_FILEDIGESTS at offset %u, count: %u\n",
+ digests_offset, digests_count);
+ break;
+ case RPMTAG_FILEDIGESTALGO:
+ if (__be32_to_cpu(entry->type) != RPM_INT32_TYPE)
+ return -EINVAL;
+
+ algo_offset = __be32_to_cpu(entry->offset);
+ algo_offset_set = true;
+
+ pr_debug("Found RPMTAG_FILEDIGESTALGO at offset %u\n",
+ algo_offset);
+ break;
+ default:
+ break;
+ }
+ }
+
+ if (!digests_offset_set)
+ return 0;
+
+ if (algo_offset_set) {
+ if (algo_offset >= data_len)
+ return -EINVAL;
+
+ if (data_len - algo_offset < sizeof(u32))
+ return -EINVAL;
+
+ pkg_pgp_algo = *(u32 *)&data[algo_offset];
+ pkg_pgp_algo = __be32_to_cpu(pkg_pgp_algo);
+ if (pkg_pgp_algo > DIGEST_ALGO_SHA224) {
+ pr_debug("Unknown PGP algo %d\n", pkg_pgp_algo);
+ return -EINVAL;
+ }
+
+ pkg_kernel_algo = pgp_algo_mapping[pkg_pgp_algo];
+ if (pkg_kernel_algo >= HASH_ALGO__LAST) {
+ pr_debug("Unknown mapping for PGP algo %d\n",
+ pkg_pgp_algo);
+ return -EINVAL;
+ }
+
+ pr_debug("Found mapping for PGP algo %d: %s\n", pkg_pgp_algo,
+ hash_algo_name[pkg_kernel_algo]);
+ }
+
+ digest_len = hash_digest_size[pkg_kernel_algo];
+
+ if (digests_offset > data_len)
+ return -EINVAL;
+
+ /* Worst case, every digest is a \0. */
+ max_digests_count = data_len - digests_offset;
+
+ /* Finite termination on digests_count loop. */
+ if (digests_count > max_digests_count)
+ return -EINVAL;
+
+ ret = digest_cache_htable_init(digest_cache, digests_count,
+ pkg_kernel_algo);
+ if (ret < 0)
+ return ret;
+
+ for (i = 0; i < digests_count; i++) {
+ if (digests_offset == data_len)
+ return -EINVAL;
+
+ if (!data[digests_offset]) {
+ digests_offset++;
+ continue;
+ }
+
+ if (data_len - digests_offset < digest_len * 2 + 1)
+ return -EINVAL;
+
+ ret = hex2bin(rpm_digest, (const char *)&data[digests_offset],
+ digest_len);
+ if (ret < 0) {
+ pr_debug("Invalid hex format for digest %s\n",
+ &data[digests_offset]);
+ return -EINVAL;
+ }
+
+ ret = digest_cache_htable_add(digest_cache, rpm_digest,
+ pkg_kernel_algo);
+ if (ret < 0)
+ return ret;
+
+ digests_offset += digest_len * 2 + 1;
+ }
+
+ return ret;
+}
diff --git a/security/digest_cache/populate.c b/security/digest_cache/populate.c
index 13645ec4bb2b..1770c8385017 100644
--- a/security/digest_cache/populate.c
+++ b/security/digest_cache/populate.c
@@ -68,6 +68,8 @@ static int digest_cache_parse_digest_list(struct digest_cache *digest_cache,
if (!strncmp(format, "tlv-", 4))
ret = digest_list_parse_tlv(digest_cache, data, data_len);
+ else if (!strncmp(format, "rpm-", 4))
+ ret = digest_list_parse_rpm(digest_cache, data, data_len);
return ret;
}
--
2.34.1
From: Roberto Sassu <[email protected]>
The digest_cache LSM can support other LSMs in their decisions of granting
access to file content and metadata.
However, the information alone about whether a digest was found in a digest
cache might not be sufficient, because for example those LSMs wouldn't know
whether the digest cache itself was created from authentic data.
Introduce digest_cache_verif_set() to let the same LSMs (or a chosen
integrity provider) evaluate the digest list being read during the creation
of the digest cache, by implementing the kernel_post_read_file LSM hook,
and let them attach their verification data to that digest cache.
Reserve space in the file descriptor security blob for the digest cache
pointer. Also introduce digest_cache_to_file_sec() to set that pointer
before calling kernel_read_file() in digest_cache_populate(), and
digest_cache_from_file_sec() to retrieve the pointer back from the file
descriptor passed by LSMs with digest_cache_verif_set().
Multiple providers are supported, in the event there are multiple
integrity LSMs active. Each provider should also provide an unique verifier
ID as an argument to digest_cache_verif_set(), so that verification data
can be distinguished.
A caller of digest_cache_get() can retrieve back the verification data by
calling digest_cache_verif_get() and passing a digest cache pointer and the
desired verifier ID.
Since directory digest caches are not populated themselves, LSMs have to do
a lookup first to get the digest cache containing the digest, call
digest_cache_from_found_t() to convert the returned digest_cache_found_t
type to a digest cache pointer, and pass that to digest_cache_verif_get().
Signed-off-by: Roberto Sassu <[email protected]>
---
include/linux/digest_cache.h | 17 +++++
security/digest_cache/Makefile | 2 +-
security/digest_cache/internal.h | 40 +++++++++++
security/digest_cache/main.c | 4 ++
security/digest_cache/populate.c | 2 +
security/digest_cache/verif.c | 116 +++++++++++++++++++++++++++++++
6 files changed, 180 insertions(+), 1 deletion(-)
create mode 100644 security/digest_cache/verif.c
diff --git a/include/linux/digest_cache.h b/include/linux/digest_cache.h
index 4872700ac205..9db8128513ca 100644
--- a/include/linux/digest_cache.h
+++ b/include/linux/digest_cache.h
@@ -44,6 +44,10 @@ void digest_cache_put(struct digest_cache *digest_cache);
digest_cache_found_t digest_cache_lookup(struct dentry *dentry,
struct digest_cache *digest_cache,
u8 *digest, enum hash_algo algo);
+int digest_cache_verif_set(struct file *file, const char *verif_id, void *data,
+ size_t size);
+void *digest_cache_verif_get(struct digest_cache *digest_cache,
+ const char *verif_id);
#else
static inline struct digest_cache *digest_cache_get(struct dentry *dentry)
@@ -62,5 +66,18 @@ digest_cache_lookup(struct dentry *dentry, struct digest_cache *digest_cache,
return 0UL;
}
+static inline int digest_cache_verif_set(struct file *file,
+ const char *verif_id, void *data,
+ size_t size)
+{
+ return -EOPNOTSUPP;
+}
+
+static inline void *digest_cache_verif_get(struct digest_cache *digest_cache,
+ const char *verif_id)
+{
+ return NULL;
+}
+
#endif /* CONFIG_SECURITY_DIGEST_CACHE */
#endif /* _LINUX_DIGEST_CACHE_H */
diff --git a/security/digest_cache/Makefile b/security/digest_cache/Makefile
index eca4076497e6..37a473c7bc28 100644
--- a/security/digest_cache/Makefile
+++ b/security/digest_cache/Makefile
@@ -4,7 +4,7 @@
obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache.o
-digest_cache-y := main.o secfs.o htable.o populate.o modsig.o
+digest_cache-y := main.o secfs.o htable.o populate.o modsig.o verif.o
digest_cache-y += parsers/tlv.o
digest_cache-y += parsers/rpm.o
diff --git a/security/digest_cache/internal.h b/security/digest_cache/internal.h
index 0d9c01dd9bc8..a266925a6cce 100644
--- a/security/digest_cache/internal.h
+++ b/security/digest_cache/internal.h
@@ -17,6 +17,21 @@
#define INIT_IN_PROGRESS 0 /* Digest cache being initialized. */
#define INVALID 1 /* Digest cache marked as invalid. */
+/**
+ * struct digest_cache_verif
+ * @list: Linked list
+ * @verif_id: Identifier of who verified the digest list
+ * @data: Opaque data set by the digest list verifier
+ *
+ * This structure contains opaque data containing the result of verification
+ * of the digest list by a verifier.
+ */
+struct digest_cache_verif {
+ struct list_head list;
+ char *verif_id;
+ void *data;
+};
+
/**
* struct read_work - Structure to schedule reading a digest list
* @work: Work structure
@@ -71,6 +86,8 @@ struct htable {
* @ref_count: Number of references to the digest cache
* @path_str: Path of the digest list the digest cache was created from
* @flags: Control flags
+ * @verif_data: Verification data regarding the digest list
+ * @verif_data_lock: Protect concurrent verification data additions
*
* This structure represents a cache of digests extracted from a digest list.
*/
@@ -79,6 +96,8 @@ struct digest_cache {
atomic_t ref_count;
char *path_str;
unsigned long flags;
+ struct list_head verif_data;
+ spinlock_t verif_data_lock;
};
/**
@@ -130,6 +149,24 @@ digest_cache_unref(struct digest_cache *digest_cache)
return (ref_is_zero) ? digest_cache : NULL;
}
+static inline void digest_cache_to_file_sec(const struct file *file,
+ struct digest_cache *digest_cache)
+{
+ struct digest_cache **digest_cache_sec;
+
+ digest_cache_sec = file->f_security + digest_cache_blob_sizes.lbs_file;
+ *digest_cache_sec = digest_cache;
+}
+
+static inline struct digest_cache *
+digest_cache_from_file_sec(const struct file *file)
+{
+ struct digest_cache **digest_cache_sec;
+
+ digest_cache_sec = file->f_security + digest_cache_blob_sizes.lbs_file;
+ return *digest_cache_sec;
+}
+
/* main.c */
struct digest_cache *digest_cache_create(struct dentry *dentry,
struct path *digest_list_path,
@@ -153,4 +190,7 @@ int digest_cache_populate(struct digest_cache *digest_cache,
/* modsig.c */
size_t digest_cache_strip_modsig(__u8 *data, size_t data_len);
+/* verif.c */
+void digest_cache_verif_free(struct digest_cache *digest_cache);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/digest_cache/main.c b/security/digest_cache/main.c
index 8e9ab99081c3..d726832e5913 100644
--- a/security/digest_cache/main.c
+++ b/security/digest_cache/main.c
@@ -49,6 +49,8 @@ static struct digest_cache *digest_cache_alloc_init(char *path_str,
atomic_set(&digest_cache->ref_count, 1);
digest_cache->flags = 0UL;
INIT_LIST_HEAD(&digest_cache->htables);
+ INIT_LIST_HEAD(&digest_cache->verif_data);
+ spin_lock_init(&digest_cache->verif_data_lock);
pr_debug("New digest cache %s (ref count: %d)\n",
digest_cache->path_str, atomic_read(&digest_cache->ref_count));
@@ -65,6 +67,7 @@ static struct digest_cache *digest_cache_alloc_init(char *path_str,
static void digest_cache_free(struct digest_cache *digest_cache)
{
digest_cache_htable_free(digest_cache);
+ digest_cache_verif_free(digest_cache);
pr_debug("Freed digest cache %s\n", digest_cache->path_str);
kfree(digest_cache->path_str);
@@ -329,6 +332,7 @@ EXPORT_SYMBOL_GPL(digest_cache_put);
struct lsm_blob_sizes digest_cache_blob_sizes __ro_after_init = {
.lbs_inode = sizeof(struct digest_cache_security),
+ .lbs_file = sizeof(struct digest_cache *),
};
/**
diff --git a/security/digest_cache/populate.c b/security/digest_cache/populate.c
index 1770c8385017..9c2fc2295310 100644
--- a/security/digest_cache/populate.c
+++ b/security/digest_cache/populate.c
@@ -123,6 +123,8 @@ int digest_cache_populate(struct digest_cache *digest_cache,
return PTR_ERR(file);
}
+ digest_cache_to_file_sec(file, digest_cache);
+
w.data = NULL;
w.file = file;
INIT_WORK_ONSTACK(&w.work, digest_cache_read_digest_list);
diff --git a/security/digest_cache/verif.c b/security/digest_cache/verif.c
new file mode 100644
index 000000000000..dd480bdc805a
--- /dev/null
+++ b/security/digest_cache/verif.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Manage verification data regarding digest lists.
+ */
+
+#define pr_fmt(fmt) "DIGEST CACHE: "fmt
+#include "internal.h"
+
+/**
+ * free_verif - Free a digest_cache_verif structure
+ * @verif: digest_cache_verif structure
+ *
+ * Free the space allocated for a digest_cache_verif structure.
+ */
+static void free_verif(struct digest_cache_verif *verif)
+{
+ kfree(verif->data);
+ kfree(verif->verif_id);
+ kfree(verif);
+}
+
+/**
+ * digest_cache_verif_set - Set digest cache verification data
+ * @file: File descriptor of the digest list being read to populate digest cache
+ * @verif_id: Verifier ID
+ * @data: Verification data (opaque)
+ * @size: Size of @data
+ *
+ * This function lets a verifier supply verification data about a digest list
+ * being read to populate the digest cache.
+ *
+ * Return: Zero on success, -ENOMEM if out of memory.
+ */
+int digest_cache_verif_set(struct file *file, const char *verif_id, void *data,
+ size_t size)
+{
+ struct digest_cache *digest_cache = digest_cache_from_file_sec(file);
+ struct digest_cache_verif *new_verif;
+
+ /*
+ * All allocations must be atomic (non-sleepable) since kprobe does not
+ * allow otherwise (kprobe is needed for testing).
+ */
+ new_verif = kzalloc(sizeof(*new_verif), GFP_ATOMIC);
+ if (!new_verif)
+ return -ENOMEM;
+
+ new_verif->verif_id = kstrdup(verif_id, GFP_ATOMIC);
+ if (!new_verif->verif_id) {
+ free_verif(new_verif);
+ return -ENOMEM;
+ }
+
+ new_verif->data = kmemdup(data, size, GFP_ATOMIC);
+ if (!new_verif->data) {
+ free_verif(new_verif);
+ return -ENOMEM;
+ }
+
+ spin_lock(&digest_cache->verif_data_lock);
+ list_add_tail_rcu(&new_verif->list, &digest_cache->verif_data);
+ spin_unlock(&digest_cache->verif_data_lock);
+ return 0;
+}
+EXPORT_SYMBOL_GPL(digest_cache_verif_set);
+
+/**
+ * digest_cache_verif_get - Get digest cache verification data
+ * @digest_cache: Digest cache
+ * @verif_id: Verifier ID
+ *
+ * This function returns the verification data previously set by a verifier
+ * with digest_cache_verif_set().
+ *
+ * Return: Verification data if found, NULL otherwise.
+ */
+void *digest_cache_verif_get(struct digest_cache *digest_cache,
+ const char *verif_id)
+{
+ struct digest_cache_verif *verif;
+ void *verif_data = NULL;
+
+ rcu_read_lock();
+ list_for_each_entry_rcu(verif, &digest_cache->verif_data, list) {
+ if (!strcmp(verif->verif_id, verif_id)) {
+ verif_data = verif->data;
+ break;
+ }
+ }
+ rcu_read_unlock();
+
+ return verif_data;
+}
+EXPORT_SYMBOL_GPL(digest_cache_verif_get);
+
+/**
+ * digest_cache_verif_free - Free all digest_cache_verif structures
+ * @digest_cache: Digest cache
+ *
+ * This function frees the space allocated for all digest_cache_verif
+ * structures in the digest cache.
+ */
+void digest_cache_verif_free(struct digest_cache *digest_cache)
+{
+ struct digest_cache_verif *p, *q;
+
+ /* No need to lock, called when nobody else has a digest cache ref. */
+ list_for_each_entry_safe(p, q, &digest_cache->verif_data, list) {
+ list_del(&p->list);
+ free_verif(p);
+ }
+}
--
2.34.1
From: Roberto Sassu <[email protected]>
In the environments where xattrs are not available (e.g. in the initial ram
disk), the digest_cache LSM cannot precisely determine which digest list in
a directory contains the desired reference digest. However, although
slower, it would be desirable to search the digest in all digest lists of
that directory.
This done in two steps. When a digest cache is being created,
digest_cache_create() invokes digest_cache_dir_create(), to generate the
list of current directory entries. Entries are placed in the list in
ascending order by the <seq num> if prepended to the file name, or at the
end of the list if not.
The resulting digest cache has the IS_DIR bit set, to distinguish it from
the digest caches created from regular files.
Second, when a digest is searched in a directory digest cache,
digest_cache_lookup() invokes digest_cache_dir_lookup_digest() to
iteratively search that digest in each directory entry generated by
digest_cache_dir_create().
That list is stable, even if new files are added or deleted from that
directory. A subsequent patch will invalidate the digest cache, forcing
next callers of digest_cache_get() to get a new directory digest cache with
the updated list of directory entries.
If the current directory entry does not have a digest cache reference,
digest_cache_dir_lookup_digest() invokes digest_cache_create() to create a
new digest cache for that entry. In either case,
digest_cache_dir_lookup_digest() calls then digest_cache_htable_lookup()
with the new/existing digest cache to search the digest. Check and
assignment of the digest cache in a directory entry is protected by the
per entry digest_cache_mutex.
The iteration stops when the digest is found. In that case,
digest_cache_dir_lookup_digest() returns the digest cache reference of the
current directory entry as the digest_cache_found_t type, so that callers
of digest_cache_lookup() don't mistakenly try to call digest_cache_put()
with that reference.
This new reference type will be used to retrieve information about the
digest cache containing the digest, which is not known in advance until the
digest search is performed.
The order of the list of directory entries influences the speed of the
digest search. A search terminates faster if less digest caches have to be
created. One way to optimize it could be to order the list of digest lists
in the same way of when they are requested at boot.
Finally, digest_cache_dir_free() releases the digest cache references
stored in the list of directory entries, and frees the list itself.
Signed-off-by: Roberto Sassu <[email protected]>
---
security/digest_cache/Makefile | 2 +-
security/digest_cache/dir.c | 192 +++++++++++++++++++++++++++++++
security/digest_cache/htable.c | 22 +++-
security/digest_cache/internal.h | 45 ++++++++
security/digest_cache/main.c | 12 ++
5 files changed, 270 insertions(+), 3 deletions(-)
create mode 100644 security/digest_cache/dir.c
diff --git a/security/digest_cache/Makefile b/security/digest_cache/Makefile
index 37a473c7bc28..e417da0383ab 100644
--- a/security/digest_cache/Makefile
+++ b/security/digest_cache/Makefile
@@ -4,7 +4,7 @@
obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache.o
-digest_cache-y := main.o secfs.o htable.o populate.o modsig.o verif.o
+digest_cache-y := main.o secfs.o htable.o populate.o modsig.o verif.o dir.o
digest_cache-y += parsers/tlv.o
digest_cache-y += parsers/rpm.o
diff --git a/security/digest_cache/dir.c b/security/digest_cache/dir.c
new file mode 100644
index 000000000000..3d684af241a2
--- /dev/null
+++ b/security/digest_cache/dir.c
@@ -0,0 +1,192 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Manage digest caches from directories.
+ */
+
+#define pr_fmt(fmt) "DIGEST CACHE: "fmt
+#include <linux/init_task.h>
+
+#include "internal.h"
+
+/**
+ * digest_cache_dir_iter - Digest cache directory iterator
+ * @__ctx: iterate_dir() context
+ * @name: Name of file in the accessed directory
+ * @namelen: String length of @name
+ * @offset: Current position in the directory stream (see man readdir)
+ * @ino: Inode number
+ * @d_type: File type
+ *
+ * This function stores the names of the files in the containing directory in
+ * a linked list. If they are in the format <seq num>-<format>-<name>, this
+ * function orders them by seq num, so that digest lists are processed in the
+ * desired order. Otherwise, if <seq num>- is not included, it adds the name at
+ * the end of the list.
+ *
+ * Return: True to continue processing, false to stop.
+ */
+static bool digest_cache_dir_iter(struct dir_context *__ctx, const char *name,
+ int namelen, loff_t offset, u64 ino,
+ unsigned int d_type)
+{
+ struct readdir_callback *ctx = container_of(__ctx, typeof(*ctx), ctx);
+ struct dir_entry *new_entry, *p;
+ unsigned int seq_num;
+ char *separator;
+ int ret;
+
+ if (!strcmp(name, ".") || !strcmp(name, ".."))
+ return true;
+
+ if (d_type != DT_REG)
+ return true;
+
+ new_entry = kmalloc(sizeof(*new_entry) + namelen + 1, GFP_KERNEL);
+ if (!new_entry)
+ return false;
+
+ memcpy(new_entry->name, name, namelen);
+ new_entry->name[namelen] = '\0';
+ new_entry->seq_num = UINT_MAX;
+ new_entry->digest_cache = NULL;
+ mutex_init(&new_entry->digest_cache_mutex);
+
+ if (new_entry->name[0] < '0' || new_entry->name[0] > '9')
+ goto out;
+
+ separator = strchr(new_entry->name, '-');
+ if (!separator)
+ goto out;
+
+ *separator = '\0';
+ ret = kstrtouint(new_entry->name, 10, &seq_num);
+ *separator = '-';
+ if (ret < 0)
+ goto out;
+
+ new_entry->seq_num = seq_num;
+
+ list_for_each_entry(p, ctx->head, list) {
+ if (seq_num <= p->seq_num) {
+ list_add(&new_entry->list, p->list.prev);
+ pr_debug("Added %s before %s in dir list\n",
+ new_entry->name, p->name);
+ return true;
+ }
+ }
+out:
+ list_add_tail(&new_entry->list, ctx->head);
+ pr_debug("Added %s to tail of dir list\n", new_entry->name);
+ return true;
+}
+
+/**
+ * digest_cache_dir_create - Create a directory digest cache
+ * @digest_cache: Digest cache
+ * @digest_list_path: Path structure of the digest list directory
+ *
+ * This function iterates over the entries of a directory, and creates a linked
+ * list of file names from that directory.
+ *
+ * Return: Zero on success, a POSIX error code otherwise.
+ */
+int digest_cache_dir_create(struct digest_cache *digest_cache,
+ struct path *digest_list_path)
+{
+ struct file *dir_file;
+ struct readdir_callback buf = {
+ .ctx.actor = digest_cache_dir_iter,
+ };
+ int ret;
+
+ dir_file = dentry_open(digest_list_path, O_RDONLY, &init_cred);
+ if (IS_ERR(dir_file)) {
+ pr_debug("Cannot access %s, ret: %ld\n", digest_cache->path_str,
+ PTR_ERR(dir_file));
+ return PTR_ERR(dir_file);
+ }
+
+ buf.head = &digest_cache->dir_entries;
+ ret = iterate_dir(dir_file, &buf.ctx);
+ if (ret < 0)
+ pr_debug("Failed to iterate directory %s\n",
+ digest_cache->path_str);
+
+ fput(dir_file);
+ return ret;
+}
+
+/**
+ * digest_cache_dir_lookup_digest - Lookup a digest
+ * @dentry: Dentry of the file whose digest is looked up
+ * @digest_list_path: Path structure of the digest list directory
+ * @digest_cache: Digest cache
+ * @digest: Digest to search
+ * @algo: Algorithm of the digest to search
+ *
+ * This function iterates over the linked list created by
+ * digest_cache_dir_create() and looks up the digest in the digest cache of
+ * each entry.
+ *
+ * Return: A digest_cache_found_t value if the digest if found, zero otherwise.
+ */
+digest_cache_found_t
+digest_cache_dir_lookup_digest(struct dentry *dentry,
+ struct path *digest_list_path,
+ struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo)
+{
+ struct digest_cache *cache;
+ struct dir_entry *dir_entry;
+ int ret;
+
+ list_for_each_entry(dir_entry, &digest_cache->dir_entries, list) {
+ mutex_lock(&dir_entry->digest_cache_mutex);
+ if (!dir_entry->digest_cache) {
+ cache = digest_cache_create(dentry, digest_list_path,
+ digest_cache->path_str,
+ dir_entry->name);
+ /* Ignore digest caches that cannot be instantiated. */
+ if (!cache) {
+ mutex_unlock(&dir_entry->digest_cache_mutex);
+ continue;
+ }
+
+ /* Consume extra ref. from digest_cache_create(). */
+ dir_entry->digest_cache = cache;
+ }
+ mutex_unlock(&dir_entry->digest_cache_mutex);
+
+ ret = digest_cache_htable_lookup(dentry,
+ dir_entry->digest_cache,
+ digest, algo);
+ if (!ret)
+ return (digest_cache_found_t)dir_entry->digest_cache;
+ }
+
+ return 0UL;
+}
+
+/**
+ * digest_cache_dir_free - Free the stored file list and put digest caches
+ * @digest_cache: Digest cache
+ *
+ * This function frees the file list created by digest_cache_create(), and puts
+ * the digest cache if a reference exists.
+ */
+void digest_cache_dir_free(struct digest_cache *digest_cache)
+{
+ struct dir_entry *p, *q;
+
+ list_for_each_entry_safe(p, q, &digest_cache->dir_entries, list) {
+ if (p->digest_cache)
+ digest_cache_put(p->digest_cache);
+
+ list_del(&p->list);
+ kfree(p);
+ }
+}
diff --git a/security/digest_cache/htable.c b/security/digest_cache/htable.c
index d2d5d8f5e5b1..8cf7400dfcf4 100644
--- a/security/digest_cache/htable.c
+++ b/security/digest_cache/htable.c
@@ -8,6 +8,8 @@
*/
#define pr_fmt(fmt) "DIGEST CACHE: "fmt
+#include <linux/namei.h>
+
#include "internal.h"
/**
@@ -210,10 +212,26 @@ digest_cache_found_t digest_cache_lookup(struct dentry *dentry,
struct digest_cache *digest_cache,
u8 *digest, enum hash_algo algo)
{
+ struct path digest_list_path;
+ digest_cache_found_t found;
int ret;
- ret = digest_cache_htable_lookup(dentry, digest_cache, digest, algo);
- return (!ret) ? (digest_cache_found_t)digest_cache : 0UL;
+ if (!test_bit(IS_DIR, &digest_cache->flags)) {
+ ret = digest_cache_htable_lookup(dentry, digest_cache, digest,
+ algo);
+ return (!ret) ? (digest_cache_found_t)digest_cache : 0UL;
+ }
+
+ ret = kern_path(digest_cache->path_str, 0, &digest_list_path);
+ if (ret < 0) {
+ pr_debug("Cannot find path %s\n", digest_cache->path_str);
+ return 0UL;
+ }
+
+ found = digest_cache_dir_lookup_digest(dentry, &digest_list_path,
+ digest_cache, digest, algo);
+ path_put(&digest_list_path);
+ return found;
}
EXPORT_SYMBOL_GPL(digest_cache_lookup);
diff --git a/security/digest_cache/internal.h b/security/digest_cache/internal.h
index a266925a6cce..dee24d48abad 100644
--- a/security/digest_cache/internal.h
+++ b/security/digest_cache/internal.h
@@ -16,6 +16,39 @@
/* Digest cache bits in flags. */
#define INIT_IN_PROGRESS 0 /* Digest cache being initialized. */
#define INVALID 1 /* Digest cache marked as invalid. */
+#define IS_DIR 2 /* Digest cache created from dir. */
+
+/**
+ * struct readdir_callback - Structure to store information for dir iteration
+ * @ctx: Context structure
+ * @head: Head of linked list of directory entries
+ *
+ * This structure stores information to be passed from the iterate_dir() caller
+ * to the directory iterator.
+ */
+struct readdir_callback {
+ struct dir_context ctx;
+ struct list_head *head;
+};
+
+/**
+ * struct dir_entry - Directory entry
+ * @list: Linked list of directory entries
+ * @digest_cache: Digest cache associated to the directory entry
+ * @digest_cache_mutex: Protects @digest_cache
+ * @seq_num: Sequence number of the directory entry from file name
+ * @name: File name of the directory entry
+ *
+ * This structure represents a directory entry with a digest cache created
+ * from that entry.
+ */
+struct dir_entry {
+ struct list_head list;
+ struct digest_cache *digest_cache;
+ struct mutex digest_cache_mutex;
+ unsigned int seq_num;
+ char name[];
+} __packed;
/**
* struct digest_cache_verif
@@ -83,6 +116,7 @@ struct htable {
/**
* struct digest_cache - Digest cache
* @htables: Hash tables (one per algorithm)
+ * @dir_entries: List of files in a directory and the digest cache
* @ref_count: Number of references to the digest cache
* @path_str: Path of the digest list the digest cache was created from
* @flags: Control flags
@@ -93,6 +127,7 @@ struct htable {
*/
struct digest_cache {
struct list_head htables;
+ struct list_head dir_entries;
atomic_t ref_count;
char *path_str;
unsigned long flags;
@@ -193,4 +228,14 @@ size_t digest_cache_strip_modsig(__u8 *data, size_t data_len);
/* verif.c */
void digest_cache_verif_free(struct digest_cache *digest_cache);
+/* dir.c */
+int digest_cache_dir_create(struct digest_cache *digest_cache,
+ struct path *digest_list_path);
+digest_cache_found_t
+digest_cache_dir_lookup_digest(struct dentry *dentry,
+ struct path *digest_list_path,
+ struct digest_cache *digest_cache, u8 *digest,
+ enum hash_algo algo);
+void digest_cache_dir_free(struct digest_cache *digest_cache);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/digest_cache/main.c b/security/digest_cache/main.c
index d726832e5913..a51c33dd07a8 100644
--- a/security/digest_cache/main.c
+++ b/security/digest_cache/main.c
@@ -51,6 +51,7 @@ static struct digest_cache *digest_cache_alloc_init(char *path_str,
INIT_LIST_HEAD(&digest_cache->htables);
INIT_LIST_HEAD(&digest_cache->verif_data);
spin_lock_init(&digest_cache->verif_data_lock);
+ INIT_LIST_HEAD(&digest_cache->dir_entries);
pr_debug("New digest cache %s (ref count: %d)\n",
digest_cache->path_str, atomic_read(&digest_cache->ref_count));
@@ -68,6 +69,7 @@ static void digest_cache_free(struct digest_cache *digest_cache)
{
digest_cache_htable_free(digest_cache);
digest_cache_verif_free(digest_cache);
+ digest_cache_dir_free(digest_cache);
pr_debug("Freed digest cache %s\n", digest_cache->path_str);
kfree(digest_cache->path_str);
@@ -178,6 +180,16 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
/* Prevent usage of partially-populated digest cache. */
set_bit(INVALID, &digest_cache->flags);
}
+ } else if (S_ISDIR(inode->i_mode)) {
+ set_bit(IS_DIR, &dig_sec->dig_owner->flags);
+
+ ret = digest_cache_dir_create(digest_cache, digest_list_path);
+ if (ret < 0) {
+ pr_debug("Failed to create dir digest cache, ret: %d (keep digest cache)\n",
+ ret);
+ /* Prevent usage of partially-populated digest cache. */
+ set_bit(INVALID, &dig_sec->dig_owner->flags);
+ }
}
/* Creation complete, notify the other lock contenders. */
--
2.34.1
From: Roberto Sassu <[email protected]>
Register five new LSM hooks, file_open, path_truncate, file_release,
inode_unlink and inode_rename, to monitor digest lists/directory
modifications.
If an action affects a digest list or the parent directory, the new LSM
hook implementations call digest_cache_reset() to set the RESET bit on the
digest cache. This will cause next calls to digest_cache_get() and
digest_cache_create() to respectively put and clear dig_user and dig_owner,
and request a new digest cache.
That does not affect other users of the old digest cache, since that one
remains valid as long as the reference count is greater than zero. However,
they can explicitly call the new function digest_cache_was_reset(), to
check if the RESET bit was set on the digest cache reference they hold.
Recreating a file digest cache means reading the digest list again and
extracting the digests. Recreating a directory digest cache, instead, does
not mean recreating the digest cache for directory entries, since those
digest caches are likely already stored in the inode security blob. It
would happen however for new files.
File digest cache reset is done on file_open, when a digest list is opened
for write, path_truncate, when a digest list is truncated (there is no
inode_truncate, file_truncate does not catch operations through the
truncate() system call), inode_unlink, when a digest list is removed, and
inode_rename when a digest list is renamed.
Directory digest cache reset is done on file_release, when a digest list is
written in the digest list directory, on inode_unlink, when a digest list
is deleted from that directory, and finally on inode_rename, when a digest
list is moved to/from that directory.
With the exception of file_release, which will always be executed (cannot
be denied), the other LSM hooks are not optimal, since the digest_cache LSM
does not know whether or not the operation will be allowed also by other
LSMs. If the operation is denied, the digest_cache LSM would do an
unnecessary reset.
Signed-off-by: Roberto Sassu <[email protected]>
---
include/linux/digest_cache.h | 6 ++
security/digest_cache/Kconfig | 1 +
security/digest_cache/Makefile | 3 +-
security/digest_cache/internal.h | 9 ++
security/digest_cache/main.c | 15 +++
security/digest_cache/reset.c | 168 +++++++++++++++++++++++++++++++
6 files changed, 201 insertions(+), 1 deletion(-)
create mode 100644 security/digest_cache/reset.c
diff --git a/include/linux/digest_cache.h b/include/linux/digest_cache.h
index 9db8128513ca..db3052c71b7a 100644
--- a/include/linux/digest_cache.h
+++ b/include/linux/digest_cache.h
@@ -48,6 +48,7 @@ int digest_cache_verif_set(struct file *file, const char *verif_id, void *data,
size_t size);
void *digest_cache_verif_get(struct digest_cache *digest_cache,
const char *verif_id);
+bool digest_cache_was_reset(struct digest_cache *digest_cache);
#else
static inline struct digest_cache *digest_cache_get(struct dentry *dentry)
@@ -79,5 +80,10 @@ static inline void *digest_cache_verif_get(struct digest_cache *digest_cache,
return NULL;
}
+static inline bool digest_cache_was_reset(struct digest_cache *digest_cache)
+{
+ return false;
+}
+
#endif /* CONFIG_SECURITY_DIGEST_CACHE */
#endif /* _LINUX_DIGEST_CACHE_H */
diff --git a/security/digest_cache/Kconfig b/security/digest_cache/Kconfig
index dc9ed8f0f883..cd397eb64140 100644
--- a/security/digest_cache/Kconfig
+++ b/security/digest_cache/Kconfig
@@ -2,6 +2,7 @@
config SECURITY_DIGEST_CACHE
bool "Digest_cache LSM"
select TLV_PARSER
+ select SECURITY_PATH
default n
help
This option enables an LSM maintaining a cache of digests
diff --git a/security/digest_cache/Makefile b/security/digest_cache/Makefile
index e417da0383ab..3d5e600a2c45 100644
--- a/security/digest_cache/Makefile
+++ b/security/digest_cache/Makefile
@@ -4,7 +4,8 @@
obj-$(CONFIG_SECURITY_DIGEST_CACHE) += digest_cache.o
-digest_cache-y := main.o secfs.o htable.o populate.o modsig.o verif.o dir.o
+digest_cache-y := main.o secfs.o htable.o populate.o modsig.o verif.o dir.o \
+ reset.o
digest_cache-y += parsers/tlv.o
digest_cache-y += parsers/rpm.o
diff --git a/security/digest_cache/internal.h b/security/digest_cache/internal.h
index bbef5ab83107..0517e648fbb7 100644
--- a/security/digest_cache/internal.h
+++ b/security/digest_cache/internal.h
@@ -18,6 +18,7 @@
#define INVALID 1 /* Digest cache marked as invalid. */
#define IS_DIR 2 /* Digest cache created from dir. */
#define DIR_PREFETCH 3 /* Prefetching requested for dir. */
+#define RESET 4 /* Digest cache to be recreated. */
/**
* struct readdir_callback - Structure to store information for dir iteration
@@ -247,4 +248,12 @@ digest_cache_dir_lookup_filename(struct dentry *dentry,
char *filename);
void digest_cache_dir_free(struct digest_cache *digest_cache);
+/* reset.c */
+int digest_cache_file_open(struct file *file);
+int digest_cache_path_truncate(const struct path *path);
+void digest_cache_file_release(struct file *file);
+int digest_cache_inode_unlink(struct inode *dir, struct dentry *dentry);
+int digest_cache_inode_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry);
+
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/digest_cache/main.c b/security/digest_cache/main.c
index e6598f81074a..b192628e30db 100644
--- a/security/digest_cache/main.c
+++ b/security/digest_cache/main.c
@@ -162,6 +162,11 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
/* Serialize check and assignment of dig_owner. */
mutex_lock(&dig_sec->dig_owner_mutex);
+ if (dig_sec->dig_owner && test_bit(RESET, &dig_sec->dig_owner->flags)) {
+ digest_cache_put(dig_sec->dig_owner);
+ dig_sec->dig_owner = NULL;
+ }
+
if (dig_sec->dig_owner) {
/* Increment ref. count for reference returned to the caller. */
digest_cache = digest_cache_ref(dig_sec->dig_owner);
@@ -394,6 +399,11 @@ struct digest_cache *digest_cache_get(struct dentry *dentry)
/* Serialize accesses to inode for which the digest cache is used. */
mutex_lock(&dig_sec->dig_user_mutex);
+ if (dig_sec->dig_user && test_bit(RESET, &dig_sec->dig_user->flags)) {
+ digest_cache_put(dig_sec->dig_user);
+ dig_sec->dig_user = NULL;
+ }
+
if (!dig_sec->dig_user) {
down_read(&default_path_sem);
/* Consume extra reference from digest_cache_create(). */
@@ -482,6 +492,11 @@ static void digest_cache_inode_free_security(struct inode *inode)
static struct security_hook_list digest_cache_hooks[] __ro_after_init = {
LSM_HOOK_INIT(inode_alloc_security, digest_cache_inode_alloc_security),
LSM_HOOK_INIT(inode_free_security, digest_cache_inode_free_security),
+ LSM_HOOK_INIT(file_open, digest_cache_file_open),
+ LSM_HOOK_INIT(path_truncate, digest_cache_path_truncate),
+ LSM_HOOK_INIT(file_release, digest_cache_file_release),
+ LSM_HOOK_INIT(inode_unlink, digest_cache_inode_unlink),
+ LSM_HOOK_INIT(inode_rename, digest_cache_inode_rename),
};
/**
diff --git a/security/digest_cache/reset.c b/security/digest_cache/reset.c
new file mode 100644
index 000000000000..b4968ac993f0
--- /dev/null
+++ b/security/digest_cache/reset.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Reset digest cache on digest lists/directory modifications.
+ */
+
+#define pr_fmt(fmt) "DIGEST CACHE: "fmt
+#include "internal.h"
+
+/**
+ * digest_cache_was_reset - Report whether or not the digest cache was reset
+ * @digest_cache: Digest cache
+ *
+ * This function reports whether or not the RESET bit was set in the digest
+ * cache.
+ *
+ * It is meant to be used by digest_cache LSM users holding a reference of a
+ * digest cache, which might need to take additional actions depending on
+ * whether or not that digest cache was reset.
+ *
+ * Return: True if the digest cache was reset, false otherwise.
+ */
+bool digest_cache_was_reset(struct digest_cache *digest_cache)
+{
+ return test_bit(RESET, &digest_cache->flags);
+}
+EXPORT_SYMBOL_GPL(digest_cache_was_reset);
+
+/**
+ * digest_cache_reset - Reset the digest cache
+ * @inode: Inode of the digest list/directory containing the digest list
+ * @reason: Reason for reset
+ *
+ * This function sets the RESET bit in the digest cache, so that
+ * digest_cache_get() and digest_cache_create() respectively release and clear
+ * dig_user and dig_owner in the inode security blob. This causes new callers
+ * of digest_cache_get() to get a new digest cache.
+ */
+static void digest_cache_reset(struct inode *inode, const char *reason)
+{
+ struct digest_cache_security *dig_sec;
+
+ dig_sec = digest_cache_get_security(inode);
+ if (unlikely(!dig_sec))
+ return;
+
+ mutex_lock(&dig_sec->dig_owner_mutex);
+ if (dig_sec->dig_owner) {
+ pr_debug("Resetting %s, reason: %s\n",
+ dig_sec->dig_owner->path_str, reason);
+ set_bit(RESET, &dig_sec->dig_owner->flags);
+ }
+ mutex_unlock(&dig_sec->dig_owner_mutex);
+}
+
+/**
+ * digest_cache_file_open - A file is being opened
+ * @file: File descriptor
+ *
+ * This function is called when a file is opened. If the inode is a digest list
+ * and is opened for write, it resets the inode dig_owner, to force rebuilding
+ * the digest cache.
+ *
+ * Return: Zero.
+ */
+int digest_cache_file_open(struct file *file)
+{
+ if (!S_ISREG(file_inode(file)->i_mode) || !(file->f_mode & FMODE_WRITE))
+ return 0;
+
+ digest_cache_reset(file_inode(file), "file_open_write");
+ return 0;
+}
+
+/**
+ * digest_cache_path_truncate - A file is being truncated
+ * @path: File path
+ *
+ * This function is called when a file is being truncated. If the inode is a
+ * digest list, it resets the inode dig_owner, to force rebuilding the digest
+ * cache.
+ *
+ * Return: Zero.
+ */
+int digest_cache_path_truncate(const struct path *path)
+{
+ struct inode *inode = d_backing_inode(path->dentry);
+
+ if (!S_ISREG(inode->i_mode))
+ return 0;
+
+ digest_cache_reset(inode, "file_truncate");
+ return 0;
+}
+
+/**
+ * digest_cache_file_release - Last reference of a file desc is being released
+ * @file: File descriptor
+ *
+ * This function is called when the last reference of a file descriptor is
+ * being released. If the parent inode is the digest list directory, the inode
+ * is a regular file and was opened for write, it resets the inode dig_owner,
+ * to force rebuilding the digest cache.
+ */
+void digest_cache_file_release(struct file *file)
+{
+ struct inode *dir = d_backing_inode(file_dentry(file)->d_parent);
+
+ if (!S_ISREG(file_inode(file)->i_mode) || !(file->f_mode & FMODE_WRITE))
+ return;
+
+ digest_cache_reset(dir, "dir_file_release");
+}
+
+/**
+ * digest_cache_inode_unlink - An inode is being removed
+ * @dir: Inode of the affected directory
+ * @dentry: Dentry of the inode being removed
+ *
+ * This function is called when an existing inode is being removed. If the
+ * inode is a digest list, or the parent inode is the digest list directory and
+ * the inode is a regular file, it resets the affected inode dig_owner, to force
+ * rebuilding the digest cache.
+ *
+ * Return: Zero.
+ */
+int digest_cache_inode_unlink(struct inode *dir, struct dentry *dentry)
+{
+ struct inode *inode = d_backing_inode(dentry);
+
+ if (!S_ISREG(inode->i_mode))
+ return 0;
+
+ digest_cache_reset(inode, "file_unlink");
+ digest_cache_reset(dir, "dir_unlink");
+ return 0;
+}
+
+/**
+ * digest_cache_inode_rename - An inode is being renamed
+ * @old_dir: Inode of the directory containing the inode being renamed
+ * @old_dentry: Dentry of the inode being renamed
+ * @new_dir: Directory where the inode will be placed into
+ * @new_dentry: Dentry of the inode after being renamed
+ *
+ * This function is called when an existing inode is being moved from a
+ * directory to another (rename). If the inode is a digest list, or that inode
+ * is moved from/to the digest list directory, it resets the affected inode
+ * dig_owner, to force rebuilding the digest cache.
+ *
+ * Return: Zero.
+ */
+int digest_cache_inode_rename(struct inode *old_dir, struct dentry *old_dentry,
+ struct inode *new_dir, struct dentry *new_dentry)
+{
+ struct inode *old_inode = d_backing_inode(old_dentry);
+
+ if (!S_ISREG(old_inode->i_mode))
+ return 0;
+
+ digest_cache_reset(old_inode, "file_rename");
+ digest_cache_reset(old_dir, "dir_rename_from");
+ digest_cache_reset(new_dir, "dir_rename_to");
+ return 0;
+}
--
2.34.1
From: Roberto Sassu <[email protected]>
A desirable goal when doing integrity measurements is that they are done
always in the same order across boots, so that the resulting PCR value
becomes predictable and suitable for sealing policies. However, due to
parallel execution of system services at boot, a deterministic order of
measurements is difficult to achieve.
The digest_cache LSM is not exempted from this issue. Under the assumption
that only the digest list is measured, and file measurements are omitted if
their digest is found in that digest list, a PCR can be predictable only if
all files belong to the same digest list. Otherwise, it will still be
unpredictable, since files accessed in a non-deterministic order will cause
digest lists to be measured in a non-deterministic order too.
Overcome this issue, if prefetching is enabled, by searching a digest list
file name in digest_list_dir_lookup_filename() among the entries of the
linked list built by digest_cache_dir_create(). If the file name does not
match, read the digest list to trigger its measurement. Otherwise, also
create a digest cache and return that to the caller. Release the extra
reference of the directory digest cache in digest_cache_new(), since it was
only used for the search and it is not going to be returned.
Prefetching needs to be explicitly enabled by setting the new
security.dig_prefetch xattr to 1 in the directory containing the digest
lists. The newly introduced function digest_cache_prefetch_requested()
checks first if the DIR_PREFETCH bit is set in dig_owner, otherwise it
reads the xattr. digest_cache_create() sets DIR_PREFETCH in dig_owner, if
prefetching is enabled, before declaring the digest cache as initialized.
Signed-off-by: Roberto Sassu <[email protected]>
---
include/uapi/linux/xattr.h | 3 +
security/digest_cache/dir.c | 55 +++++++++++++++++-
security/digest_cache/internal.h | 11 +++-
security/digest_cache/main.c | 98 ++++++++++++++++++++++++++++++--
security/digest_cache/populate.c | 8 ++-
security/digest_cache/verif.c | 5 +-
6 files changed, 171 insertions(+), 9 deletions(-)
diff --git a/include/uapi/linux/xattr.h b/include/uapi/linux/xattr.h
index 8a58cf4bce65..8af33d38d9e8 100644
--- a/include/uapi/linux/xattr.h
+++ b/include/uapi/linux/xattr.h
@@ -57,6 +57,9 @@
#define XATTR_DIGEST_LIST_SUFFIX "digest_list"
#define XATTR_NAME_DIGEST_LIST XATTR_SECURITY_PREFIX XATTR_DIGEST_LIST_SUFFIX
+#define XATTR_DIG_PREFETCH_SUFFIX "dig_prefetch"
+#define XATTR_NAME_DIG_PREFETCH XATTR_SECURITY_PREFIX XATTR_DIG_PREFETCH_SUFFIX
+
#define XATTR_SELINUX_SUFFIX "selinux"
#define XATTR_NAME_SELINUX XATTR_SECURITY_PREFIX XATTR_SELINUX_SUFFIX
diff --git a/security/digest_cache/dir.c b/security/digest_cache/dir.c
index 3d684af241a2..a5ae37822717 100644
--- a/security/digest_cache/dir.c
+++ b/security/digest_cache/dir.c
@@ -54,6 +54,7 @@ static bool digest_cache_dir_iter(struct dir_context *__ctx, const char *name,
new_entry->seq_num = UINT_MAX;
new_entry->digest_cache = NULL;
mutex_init(&new_entry->digest_cache_mutex);
+ new_entry->prefetched = false;
if (new_entry->name[0] < '0' || new_entry->name[0] > '9')
goto out;
@@ -127,6 +128,7 @@ int digest_cache_dir_create(struct digest_cache *digest_cache,
* @digest_cache: Digest cache
* @digest: Digest to search
* @algo: Algorithm of the digest to search
+ * @filename: File name of the digest list to search
*
* This function iterates over the linked list created by
* digest_cache_dir_create() and looks up the digest in the digest cache of
@@ -149,7 +151,8 @@ digest_cache_dir_lookup_digest(struct dentry *dentry,
if (!dir_entry->digest_cache) {
cache = digest_cache_create(dentry, digest_list_path,
digest_cache->path_str,
- dir_entry->name);
+ dir_entry->name, false,
+ false);
/* Ignore digest caches that cannot be instantiated. */
if (!cache) {
mutex_unlock(&dir_entry->digest_cache_mutex);
@@ -158,6 +161,8 @@ digest_cache_dir_lookup_digest(struct dentry *dentry,
/* Consume extra ref. from digest_cache_create(). */
dir_entry->digest_cache = cache;
+ /* Digest list was read, mark entry as prefetched. */
+ dir_entry->prefetched = true;
}
mutex_unlock(&dir_entry->digest_cache_mutex);
@@ -171,6 +176,54 @@ digest_cache_dir_lookup_digest(struct dentry *dentry,
return 0UL;
}
+/**
+ * digest_cache_dir_lookup_filename - Lookup a digest list
+ * @dentry: Dentry of the file whose digest list is looked up
+ * @digest_list_path: Path structure of the digest list directory
+ * @digest_cache: Digest cache
+ * @filename: File name of the digest list to search
+ *
+ * This function iterates over the linked list created by
+ * digest_cache_dir_create() and looks up a digest list with a matching file
+ * name among the entries. If there is no match, it prefetches (reads) the
+ * current digest list. Otherwise, it returns the digest cache pointer from
+ * digest_cache_create() to the caller.
+ *
+ * Return: A digest cache pointer if the digest list if found, NULL otherwise.
+ */
+struct digest_cache *
+digest_cache_dir_lookup_filename(struct dentry *dentry,
+ struct path *digest_list_path,
+ struct digest_cache *digest_cache,
+ char *filename)
+{
+ struct digest_cache *cache;
+ struct dir_entry *dir_entry;
+ bool filename_found;
+
+ list_for_each_entry(dir_entry, &digest_cache->dir_entries, list) {
+ mutex_lock(&dir_entry->digest_cache_mutex);
+ filename_found = !strcmp(dir_entry->name, filename);
+ if (!filename_found && dir_entry->prefetched) {
+ mutex_unlock(&dir_entry->digest_cache_mutex);
+ continue;
+ }
+
+ cache = digest_cache_create(dentry, digest_list_path,
+ digest_cache->path_str,
+ dir_entry->name, false,
+ filename_found ? false : true);
+
+ dir_entry->prefetched = true;
+ mutex_unlock(&dir_entry->digest_cache_mutex);
+
+ if (filename_found)
+ return cache;
+ }
+
+ return NULL;
+}
+
/**
* digest_cache_dir_free - Free the stored file list and put digest caches
* @digest_cache: Digest cache
diff --git a/security/digest_cache/internal.h b/security/digest_cache/internal.h
index dee24d48abad..bbef5ab83107 100644
--- a/security/digest_cache/internal.h
+++ b/security/digest_cache/internal.h
@@ -17,6 +17,7 @@
#define INIT_IN_PROGRESS 0 /* Digest cache being initialized. */
#define INVALID 1 /* Digest cache marked as invalid. */
#define IS_DIR 2 /* Digest cache created from dir. */
+#define DIR_PREFETCH 3 /* Prefetching requested for dir. */
/**
* struct readdir_callback - Structure to store information for dir iteration
@@ -37,6 +38,7 @@ struct readdir_callback {
* @digest_cache: Digest cache associated to the directory entry
* @digest_cache_mutex: Protects @digest_cache
* @seq_num: Sequence number of the directory entry from file name
+ * @prefetched: Whether the digest list has been already prefetched
* @name: File name of the directory entry
*
* This structure represents a directory entry with a digest cache created
@@ -47,6 +49,7 @@ struct dir_entry {
struct digest_cache *digest_cache;
struct mutex digest_cache_mutex;
unsigned int seq_num;
+ bool prefetched;
char name[];
} __packed;
@@ -205,7 +208,8 @@ digest_cache_from_file_sec(const struct file *file)
/* main.c */
struct digest_cache *digest_cache_create(struct dentry *dentry,
struct path *digest_list_path,
- char *path_str, char *filename);
+ char *path_str, char *filename,
+ bool prefetch_req, bool prefetch);
/* htable.c */
int digest_cache_htable_init(struct digest_cache *digest_cache, u64 num_digests,
@@ -236,6 +240,11 @@ digest_cache_dir_lookup_digest(struct dentry *dentry,
struct path *digest_list_path,
struct digest_cache *digest_cache, u8 *digest,
enum hash_algo algo);
+struct digest_cache *
+digest_cache_dir_lookup_filename(struct dentry *dentry,
+ struct path *digest_list_path,
+ struct digest_cache *digest_cache,
+ char *filename);
void digest_cache_dir_free(struct digest_cache *digest_cache);
#endif /* _DIGEST_CACHE_INTERNAL_H */
diff --git a/security/digest_cache/main.c b/security/digest_cache/main.c
index a51c33dd07a8..e6598f81074a 100644
--- a/security/digest_cache/main.c
+++ b/security/digest_cache/main.c
@@ -82,6 +82,8 @@ static void digest_cache_free(struct digest_cache *digest_cache)
* @digest_list_path: Path structure of the digest list
* @path_str: Path string of the digest list
* @filename: Digest list file name (can be an empty string)
+ * @prefetch_req: Whether prefetching has been requested
+ * @prefetch: Whether prefetching of a digest list is being done
*
* This function first locates, from the passed path, the digest list inode
* from which the digest cache will be created or retrieved (if it already
@@ -108,7 +110,8 @@ static void digest_cache_free(struct digest_cache *digest_cache)
*/
struct digest_cache *digest_cache_create(struct dentry *dentry,
struct path *digest_list_path,
- char *path_str, char *filename)
+ char *path_str, char *filename,
+ bool prefetch_req, bool prefetch)
{
struct path file_path;
struct digest_cache *digest_cache = NULL;
@@ -136,11 +139,21 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
* digest cache is populated from.
*/
if (d_backing_inode(dentry) == inode)
- return NULL;
+ goto out;
/* No support for nested directories. */
if (!S_ISREG(inode->i_mode))
- return NULL;
+ goto out;
+
+ if (prefetch) {
+ /* Fine to fail, we are just prefetching. */
+ ret = digest_cache_populate(NULL, digest_list_path,
+ path_str, filename);
+ pr_debug("Digest list %s/%s %s prefetched\n",
+ path_str, filename,
+ !ret ? "has been" : "cannot be");
+ goto out;
+ }
}
dig_sec = digest_cache_get_security(inode);
@@ -169,6 +182,11 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
/* Make the other lock contenders wait until creation complete. */
set_bit(INIT_IN_PROGRESS, &dig_sec->dig_owner->flags);
+
+ /* Set DIR_PREFETCH if prefetching was requested. */
+ if (prefetch_req)
+ set_bit(DIR_PREFETCH, &digest_cache->flags);
+
mutex_unlock(&dig_sec->dig_owner_mutex);
if (S_ISREG(inode->i_mode)) {
@@ -213,6 +231,52 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
return digest_cache;
}
+/**
+ * digest_cache_prefetch_requested - Verify if prefetching is requested
+ * @digest_list_path: Path structure of the digest list directory
+ * @path_str: Path string of the digest list directory
+ *
+ * This function verifies whether or not digest list prefetching is requested.
+ * If dig_owner exists in the inode security blob, it checks the DIR_PREFETCH
+ * bit (faster). Otherwise, it reads the new security.dig_prefetch xattr.
+ *
+ * Return: True if prefetching is requested, false otherwise.
+ */
+static bool digest_cache_prefetch_requested(struct path *digest_list_path,
+ char *path_str)
+{
+ struct digest_cache_security *dig_sec;
+ bool prefetch_req = false;
+ char prefetch_value;
+ struct inode *inode;
+ int ret;
+
+ inode = d_backing_inode(digest_list_path->dentry);
+ dig_sec = digest_cache_get_security(inode);
+ if (unlikely(!dig_sec))
+ return false;
+
+ mutex_lock(&dig_sec->dig_owner_mutex);
+ if (dig_sec->dig_owner) {
+ /* Reliable test: DIR_PREFETCH set with dig_owner_mutex held. */
+ prefetch_req = test_bit(DIR_PREFETCH,
+ &dig_sec->dig_owner->flags);
+ mutex_unlock(&dig_sec->dig_owner_mutex);
+ return prefetch_req;
+ }
+ mutex_unlock(&dig_sec->dig_owner_mutex);
+
+ ret = vfs_getxattr(&nop_mnt_idmap, digest_list_path->dentry,
+ XATTR_NAME_DIG_PREFETCH, &prefetch_value, 1);
+ if (ret == 1 && prefetch_value == '1') {
+ pr_debug("Prefetching has been enabled for directory %s\n",
+ path_str);
+ prefetch_req = true;
+ }
+
+ return prefetch_req;
+}
+
/**
* digest_cache_new - Retrieve digest list file name and request digest cache
* @dentry: Dentry of the inode for which the digest cache will be used
@@ -223,13 +287,19 @@ struct digest_cache *digest_cache_create(struct dentry *dentry,
* with that file name. If security.digest_list is not found, this function
* requests the creation of a digest cache on the parent directory.
*
+ * On prefetching, if the default path is a directory and if
+ * security.digest_list is found, this function first retrieves the directory
+ * digest cache, and then calls digest_cache_dir_lookup_filename() to retrieve
+ * the desired digest cache in that directory.
+ *
* Return: A new digest cache on success, NULL on error.
*/
static struct digest_cache *digest_cache_new(struct dentry *dentry)
{
char filename[NAME_MAX + 1] = { 0 };
- struct digest_cache *digest_cache = NULL;
+ struct digest_cache *digest_cache = NULL, *found;
struct path default_path;
+ bool prefetch_req = false;
int ret;
ret = kern_path(default_path_str, 0, &default_path);
@@ -266,9 +336,27 @@ static struct digest_cache *digest_cache_new(struct dentry *dentry)
pr_debug("Found %s xattr in %s, default path: %s, digest list: %s\n",
XATTR_NAME_DIGEST_LIST, dentry->d_name.name, default_path_str,
filename);
+
+ /* On prefetching, retrieve the directory digest cache. */
+ if (filename[0])
+ prefetch_req = digest_cache_prefetch_requested(&default_path,
+ default_path_str);
create:
digest_cache = digest_cache_create(dentry, &default_path,
- default_path_str, filename);
+ default_path_str,
+ !prefetch_req ? filename : "",
+ prefetch_req, false);
+ if (!digest_cache)
+ goto out;
+
+ if (prefetch_req) {
+ /* Find the digest cache with a matching file name. */
+ found = digest_cache_dir_lookup_filename(dentry, &default_path,
+ digest_cache,
+ filename);
+ digest_cache_put(digest_cache);
+ digest_cache = found;
+ }
out:
path_put(&default_path);
return digest_cache;
diff --git a/security/digest_cache/populate.c b/security/digest_cache/populate.c
index 9c2fc2295310..17e7b011c367 100644
--- a/security/digest_cache/populate.c
+++ b/security/digest_cache/populate.c
@@ -143,6 +143,12 @@ int digest_cache_populate(struct digest_cache *digest_cache,
return ret;
}
+ /* The caller wants just to read digest lists. */
+ if (!digest_cache) {
+ ret = 0;
+ goto out_vfree;
+ }
+
data_len = digest_cache_strip_modsig(data, ret);
/* Digest list parsers initialize the hash table and add the digests. */
@@ -151,7 +157,7 @@ int digest_cache_populate(struct digest_cache *digest_cache,
if (ret < 0)
pr_debug("Error parsing digest list %s%s%s, ret: %d\n",
path_str, filename[0] ? "/" : "", filename, ret);
-
+out_vfree:
vfree(data);
return ret;
}
diff --git a/security/digest_cache/verif.c b/security/digest_cache/verif.c
index dd480bdc805a..9599d1832529 100644
--- a/security/digest_cache/verif.c
+++ b/security/digest_cache/verif.c
@@ -33,7 +33,7 @@ static void free_verif(struct digest_cache_verif *verif)
* This function lets a verifier supply verification data about a digest list
* being read to populate the digest cache.
*
- * Return: Zero on success, -ENOMEM if out of memory.
+ * Return: Zero on success, -ENOMEM if out of memory, -ENOENT on prefetching.
*/
int digest_cache_verif_set(struct file *file, const char *verif_id, void *data,
size_t size)
@@ -41,6 +41,9 @@ int digest_cache_verif_set(struct file *file, const char *verif_id, void *data,
struct digest_cache *digest_cache = digest_cache_from_file_sec(file);
struct digest_cache_verif *new_verif;
+ if (!digest_cache)
+ return -ENOENT;
+
/*
* All allocations must be atomic (non-sleepable) since kprobe does not
* allow otherwise (kprobe is needed for testing).
--
2.34.1
From: Roberto Sassu <[email protected]>
Add tests to verify the correctness of the digest_cache LSM, in all_test.c.
Add the kernel module digest_cache_kern.ko, to let all_test call the API
of the digest_cache LSM through the newly introduced digest_cache_test file
in securityfs.
Test coverage information:
File 'security/digest_cache/reset.c'
Lines executed:94.59% of 37
File 'security/digest_cache/main.c'
Lines executed:91.67% of 192
File 'security/digest_cache/modsig.c'
Lines executed:42.86% of 21
File 'security/digest_cache/htable.c'
Lines executed:93.02% of 86
File 'security/digest_cache/populate.c'
Lines executed:92.86% of 56
File 'security/digest_cache/verif.c'
Lines executed:89.74% of 39
File 'security/digest_cache/dir.c'
Lines executed:92.31% of 91
File 'security/digest_cache/secfs.c'
Lines executed:57.14% of 21
File 'security/digest_cache/parsers/tlv.c'
Lines executed:79.75% of 79
File 'security/digest_cache/parsers/rpm.c'
Lines executed:88.46% of 78
Signed-off-by: Roberto Sassu <[email protected]>
---
MAINTAINERS | 1 +
tools/testing/selftests/Makefile | 1 +
.../testing/selftests/digest_cache/.gitignore | 3 +
tools/testing/selftests/digest_cache/Makefile | 23 +
.../testing/selftests/digest_cache/all_test.c | 706 ++++++++++++++++++
tools/testing/selftests/digest_cache/common.c | 79 ++
tools/testing/selftests/digest_cache/common.h | 131 ++++
.../selftests/digest_cache/common_user.c | 47 ++
.../selftests/digest_cache/common_user.h | 17 +
tools/testing/selftests/digest_cache/config | 1 +
.../selftests/digest_cache/generators.c | 248 ++++++
.../selftests/digest_cache/generators.h | 19 +
.../selftests/digest_cache/testmod/Makefile | 16 +
.../selftests/digest_cache/testmod/kern.c | 499 +++++++++++++
14 files changed, 1791 insertions(+)
create mode 100644 tools/testing/selftests/digest_cache/.gitignore
create mode 100644 tools/testing/selftests/digest_cache/Makefile
create mode 100644 tools/testing/selftests/digest_cache/all_test.c
create mode 100644 tools/testing/selftests/digest_cache/common.c
create mode 100644 tools/testing/selftests/digest_cache/common.h
create mode 100644 tools/testing/selftests/digest_cache/common_user.c
create mode 100644 tools/testing/selftests/digest_cache/common_user.h
create mode 100644 tools/testing/selftests/digest_cache/config
create mode 100644 tools/testing/selftests/digest_cache/generators.c
create mode 100644 tools/testing/selftests/digest_cache/generators.h
create mode 100644 tools/testing/selftests/digest_cache/testmod/Makefile
create mode 100644 tools/testing/selftests/digest_cache/testmod/kern.c
diff --git a/MAINTAINERS b/MAINTAINERS
index 3e3236dd0b26..ee52cc664bc7 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6160,6 +6160,7 @@ M: Roberto Sassu <[email protected]>
L: [email protected]
S: Maintained
F: security/digest_cache/
+F: tools/testing/selftests/digest_cache/
DIGITEQ AUTOMOTIVE MGB4 V4L2 DRIVER
M: Martin Tuma <[email protected]>
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 1107be84ea95..01de54bb60a3 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -13,6 +13,7 @@ TARGETS += core
TARGETS += cpufreq
TARGETS += cpu-hotplug
TARGETS += damon
+TARGETS += digest_cache
TARGETS += dmabuf-heaps
TARGETS += drivers/dma-buf
TARGETS += drivers/s390x/uvdevice
diff --git a/tools/testing/selftests/digest_cache/.gitignore b/tools/testing/selftests/digest_cache/.gitignore
new file mode 100644
index 000000000000..392096e18f4e
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/.gitignore
@@ -0,0 +1,3 @@
+/*.mod
+/*_test
+/*.ko
diff --git a/tools/testing/selftests/digest_cache/Makefile b/tools/testing/selftests/digest_cache/Makefile
new file mode 100644
index 000000000000..7b3a465c08b4
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/Makefile
@@ -0,0 +1,23 @@
+# SPDX-License-Identifier: GPL-2.0
+TEST_GEN_PROGS_EXTENDED = digest_cache_kern.ko
+TEST_GEN_PROGS := all_test
+
+$(OUTPUT)/%.ko: $(wildcard testmod/Makefile testmod/kern.c common.c common.h])
+ $(call msg,MOD,,$@)
+ $(Q)$(MAKE) -C testmod install
+
+LOCAL_HDRS += common.h common_user.h generators.h
+CFLAGS += -ggdb -Wall -Wextra $(KHDR_INCLUDES)
+
+OVERRIDE_TARGETS := 1
+override define CLEAN
+ $(call msg,CLEAN)
+ $(Q)$(MAKE) -C testmod clean
+ rm -Rf $(TEST_GEN_PROGS)
+ rm -Rf $(OUTPUT)/common.o $(OUTPUT)/common_user.o $(OUTPUT)/generators.o
+ rm -Rf $(OUTPUT)/common.mod
+endef
+
+include ../lib.mk
+
+$(OUTPUT)/all_test: common.c common_user.c generators.c
diff --git a/tools/testing/selftests/digest_cache/all_test.c b/tools/testing/selftests/digest_cache/all_test.c
new file mode 100644
index 000000000000..8989efaf04c6
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/all_test.c
@@ -0,0 +1,706 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Implement the tests of the digest_cache LSM.
+ */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <limits.h>
+#include <fts.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <sys/xattr.h>
+
+#include "generators.h"
+
+#include "../kselftest_harness.h"
+#include "../../../../include/uapi/linux/xattr.h"
+
+#define BASE_DIR_TEMPLATE "/tmp/digest_cache_test_dirXXXXXX"
+#define DIGEST_LISTS_SUBDIR "digest_lists"
+#define NUM_DIGEST_LISTS_PREFETCH MAX_WORKS
+
+FIXTURE(shared_data) {
+ char base_dir[sizeof(BASE_DIR_TEMPLATE)];
+ char digest_lists_dir[sizeof(BASE_DIR_TEMPLATE) +
+ sizeof(DIGEST_LISTS_SUBDIR)];
+ int base_dirfd, digest_lists_dirfd, kernfd, pathfd, cmd_len;
+};
+
+FIXTURE_SETUP(shared_data)
+{
+ char cmd[1024];
+ int i, cmd_len;
+
+ /* Create the base directory. */
+ snprintf(self->base_dir, sizeof(self->base_dir), BASE_DIR_TEMPLATE);
+ ASSERT_NE(NULL, mkdtemp(self->base_dir));
+
+ /* Open base directory. */
+ self->base_dirfd = open(self->base_dir, O_RDONLY | O_DIRECTORY);
+ ASSERT_NE(-1, self->base_dirfd);
+
+ /* Create the digest_lists subdirectory. */
+ snprintf(self->digest_lists_dir, sizeof(self->digest_lists_dir),
+ "%s/%s", self->base_dir, DIGEST_LISTS_SUBDIR);
+ ASSERT_EQ(0, mkdirat(self->base_dirfd, DIGEST_LISTS_SUBDIR, 0600));
+ self->digest_lists_dirfd = openat(self->base_dirfd, DIGEST_LISTS_SUBDIR,
+ O_RDONLY | O_DIRECTORY);
+ ASSERT_NE(-1, self->digest_lists_dirfd);
+
+ /* Open kernel test interface. */
+ self->kernfd = open(DIGEST_CACHE_TEST_INTERFACE, O_RDWR, 0600);
+ ASSERT_NE(-1, self->kernfd);
+
+ /* Open kernel digest list path interface. */
+ self->pathfd = open(DIGEST_CACHE_PATH_INTERFACE, O_RDWR, 0600);
+ ASSERT_NE(-1, self->pathfd);
+ /* Write the path of the digest lists directory. */
+ ASSERT_LT(0, write(self->pathfd, self->digest_lists_dir,
+ strlen(self->digest_lists_dir)));
+
+ /* Ensure that no verifier is enabled at the beginning of a test. */
+ for (i = 0; i < VERIF__LAST; i++) {
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_DISABLE_VERIF],
+ verifs_str[i]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+ }
+}
+
+FIXTURE_TEARDOWN(shared_data)
+{
+ FTS *fts = NULL;
+ FTSENT *ftsent;
+ int fts_flags = (FTS_PHYSICAL | FTS_COMFOLLOW | FTS_NOCHDIR | FTS_XDEV);
+ char *paths[2] = { self->base_dir, NULL };
+ char cmd[1024];
+ int cmd_len;
+
+ /* Close digest_lists subdirectory. */
+ close(self->digest_lists_dirfd);
+
+ /* Close base directory. */
+ close(self->base_dirfd);
+
+ /* Delete files and directories. */
+ fts = fts_open(paths, fts_flags, NULL);
+ if (fts) {
+ while ((ftsent = fts_read(fts)) != NULL) {
+ switch (ftsent->fts_info) {
+ case FTS_DP:
+ rmdir(ftsent->fts_accpath);
+ break;
+ case FTS_F:
+ case FTS_SL:
+ case FTS_SLNONE:
+ case FTS_DEFAULT:
+ unlink(ftsent->fts_accpath);
+ break;
+ default:
+ break;
+ }
+ }
+ }
+
+ /* Release digest cache reference, if the test was interrupted. */
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s",
+ commands_str[DIGEST_CACHE_PUT]);
+ write(self->kernfd, cmd, cmd_len);
+
+ /* Close kernel test interface. */
+ close(self->kernfd);
+
+ /* Close kernel digest list path interface. */
+ close(self->pathfd);
+}
+
+static int query_test(int kernfd, char *base_dir, char *filename,
+ enum hash_algo algo, int start_number, int num_digests)
+{
+ u8 digest[MAX_DIGEST_SIZE] = { 0 };
+ char digest_str[MAX_DIGEST_SIZE * 2 + 1] = { 0 };
+ int digest_len = hash_digest_size[algo];
+ char cmd[1024];
+ int ret, i, cmd_len;
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/%s",
+ commands_str[DIGEST_CACHE_GET], base_dir, filename);
+ ret = write(kernfd, cmd, cmd_len);
+ if (ret != cmd_len)
+ return -errno;
+
+ ret = 0;
+
+ *(u32 *)digest = start_number;
+
+ for (i = 0; i < num_digests; i++) {
+ bin2hex(digest_str, digest, digest_len);
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/%s|%s:%s",
+ commands_str[DIGEST_CACHE_LOOKUP], base_dir,
+ filename, hash_algo_name[algo], digest_str);
+ ret = write(kernfd, cmd, cmd_len);
+ if (ret != cmd_len) {
+ ret = -errno;
+ goto out;
+ } else {
+ ret = 0;
+ }
+
+ (*(u32 *)digest)++;
+ }
+out:
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s",
+ commands_str[DIGEST_CACHE_PUT]);
+ write(kernfd, cmd, cmd_len);
+ return ret;
+}
+
+static enum pgp_algos get_pgp_algo(enum hash_algo algo)
+{
+ long unsigned i;
+
+ for (i = DIGEST_ALGO_MD5; i < ARRAY_SIZE(pgp_algo_mapping); i++)
+ if (pgp_algo_mapping[i] == algo)
+ return i;
+
+ return DIGEST_ALGO_SHA224 + 1;
+}
+
+static void test_parser(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata,
+ char *digest_list_filename, char *filename,
+ enum hash_algo algo, int start_number, int num_digests,
+ unsigned int failure)
+{
+ int expected_ret = (failure) ? -ENOENT : 0;
+
+ if (!strncmp(digest_list_filename, "tlv-", 4)) {
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd,
+ digest_list_filename, algo,
+ start_number, num_digests,
+ (enum tlv_failures)failure));
+ } else if (!strncmp(digest_list_filename, "rpm-", 4)) {
+ enum pgp_algos pgp_algo = get_pgp_algo(algo);
+
+ if (pgp_algo == DIGEST_ALGO_SHA224 + 1)
+ return;
+
+ ASSERT_EQ(0, gen_rpm_list(self->digest_lists_dirfd,
+ digest_list_filename, algo, pgp_algo,
+ start_number, num_digests,
+ (enum rpm_failures)failure));
+ }
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, filename,
+ digest_list_filename));
+ ASSERT_EQ(expected_ret, query_test(self->kernfd, self->base_dir,
+ filename, algo, start_number,
+ num_digests));
+
+ unlinkat(self->digest_lists_dirfd, digest_list_filename, 0);
+ unlinkat(self->base_dirfd, filename, 0);
+}
+
+/*
+ * Verify that the tlv digest list parser returns success on well-formatted
+ * digest lists, for each defined hash algorithm.
+ */
+TEST_F(shared_data, tlv_parser_ok)
+{
+ enum hash_algo algo;
+
+ /* Test every known algorithm. */
+ for (algo = 0; algo < HASH_ALGO__LAST; algo++)
+ test_parser(self, _metadata, "tlv-digest_list", "file", algo,
+ 0, 5, TLV_NO_FAILURE);
+}
+
+/*
+ * Verify that the tlv digest list parser returns failure on invalid digest
+ * lists.
+ */
+TEST_F(shared_data, tlv_parser_error)
+{
+ enum tlv_failures failure;
+
+ /* Test every failure. */
+ for (failure = 0; failure < TLV_FAILURE__LAST; failure++)
+ test_parser(self, _metadata, "tlv-digest_list", "file",
+ HASH_ALGO_SHA224, 0, 1, failure);
+}
+
+/*
+ * Verify that the rpm digest list parser returns success on well-formatted
+ * digest lists, for each defined hash algorithm.
+ */
+TEST_F(shared_data, rpm_parser_ok)
+{
+ enum hash_algo algo;
+
+ /* Test every known algorithm. */
+ for (algo = 0; algo < HASH_ALGO__LAST; algo++)
+ test_parser(self, _metadata, "rpm-digest_list", "file", algo,
+ 0, 5, RPM_NO_FAILURE);
+}
+
+/*
+ * Verify that the rpm digest list parser returns failure on invalid digest
+ * lists.
+ */
+TEST_F(shared_data, rpm_parser_error)
+{
+ enum rpm_failures failure;
+
+ /* Test every failure. */
+ for (failure = 0; failure < RPM_FAILURE__LAST; failure++)
+ test_parser(self, _metadata, "rpm-digest_list", "file",
+ HASH_ALGO_SHA224, 0, 1, failure);
+}
+
+static void test_default_path(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata, bool file)
+{
+ char path[PATH_MAX];
+ size_t path_len;
+
+ if (file) {
+ path_len = snprintf(path, sizeof(path),
+ "%s/%s/tlv-digest_list", self->base_dir,
+ DIGEST_LISTS_SUBDIR);
+ ASSERT_LT(0, write(self->pathfd, path, path_len));
+ }
+
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd, "tlv-digest_list",
+ HASH_ALGO_SHA1, 0, 1, TLV_NO_FAILURE));
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file", NULL));
+
+ ASSERT_EQ(0, query_test(self->kernfd, self->base_dir, "file",
+ HASH_ALGO_SHA1, 0, 1));
+}
+
+/*
+ * Verify that the digest cache created from the default path (regular file)
+ * can be retrieved and used for lookup.
+ */
+TEST_F(shared_data, default_path_file)
+{
+ test_default_path(self, _metadata, true);
+}
+
+/*
+ * Verify that the digest cache created from the default path (directory)
+ * can be retrieved and used for lookup.
+ */
+TEST_F(shared_data, default_path_dir)
+{
+ test_default_path(self, _metadata, false);
+}
+
+static void test_file_changes(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata,
+ enum file_changes change)
+{
+ char digest_list_filename[] = "tlv-digest_list";
+ char digest_list_filename_new[] = "tlv-digest_list6";
+ char digest_list_path[sizeof(self->digest_lists_dir) +
+ sizeof(digest_list_filename)];
+ int fd;
+
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd, digest_list_filename,
+ HASH_ALGO_SHA1, 0, 1, TLV_NO_FAILURE));
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file", digest_list_filename));
+
+ ASSERT_EQ(0, query_test(self->kernfd, self->base_dir, "file",
+ HASH_ALGO_SHA1, 0, 1));
+
+ switch (change) {
+ case FILE_WRITE:
+ fd = openat(self->digest_lists_dirfd, digest_list_filename,
+ O_WRONLY);
+ ASSERT_NE(-1, fd);
+
+ ASSERT_EQ(4, write(fd, "1234", 4));
+ close(fd);
+ break;
+ case FILE_TRUNCATE:
+ snprintf(digest_list_path, sizeof(digest_list_path),
+ "%s/%s", self->digest_lists_dir, digest_list_filename);
+ ASSERT_EQ(0, truncate(digest_list_path, 4));
+ break;
+ case FILE_UNLINK:
+ ASSERT_EQ(0, unlinkat(self->digest_lists_dirfd,
+ digest_list_filename, 0));
+ break;
+ case FILE_RENAME:
+ ASSERT_EQ(0, renameat(self->digest_lists_dirfd,
+ digest_list_filename,
+ self->digest_lists_dirfd,
+ digest_list_filename_new));
+ break;
+ default:
+ break;
+ }
+
+ ASSERT_NE(0, query_test(self->kernfd, self->base_dir, "file",
+ HASH_ALGO_SHA1, 0, 1));
+}
+
+/*
+ * Verify that operations on a digest list cause a reset of the digest cache,
+ * and that the digest is not found in the invalid/missing digest list.
+ */
+TEST_F(shared_data, file_reset)
+{
+ enum file_changes change;
+
+ /* Test for every file change. */
+ for (change = 0; change < FILE_CHANGE__LAST; change++)
+ test_file_changes(self, _metadata, change);
+}
+
+static void query_test_with_failures(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata,
+ int start_number, int num_digests,
+ int *removed, int num_removed)
+{
+ int i, j, expected_ret;
+
+ for (i = start_number; i < start_number + num_digests; i++) {
+ expected_ret = 0;
+
+ for (j = 0; j < num_removed; j++) {
+ if (removed[j] == i) {
+ expected_ret = -ENOENT;
+ break;
+ }
+ }
+
+ ASSERT_EQ(expected_ret, query_test(self->kernfd, self->base_dir,
+ "file", HASH_ALGO_SHA1, i,
+ 1));
+ }
+}
+
+/*
+ * Verify that changes in the digest list directory are monitored and that
+ * a digest cannot be found if the respective digest list file has been moved
+ * away from the directory, and that a digest can be found if the respective
+ * digest list has been moved/created in the directory.
+ */
+TEST_F(shared_data, dir_reset)
+{
+ char digest_list_filename[NAME_MAX + 1];
+ int i, removed[10];
+
+ for (i = 0; i < 10; i++) {
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "tlv-digest_list%d", i);
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd,
+ digest_list_filename, HASH_ALGO_SHA1,
+ i, 1, TLV_NO_FAILURE));
+ }
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file", NULL));
+
+ query_test_with_failures(self, _metadata, 0, 10, removed, 0);
+
+ ASSERT_EQ(0, unlinkat(self->digest_lists_dirfd, "tlv-digest_list7", 0));
+
+ removed[0] = 7;
+
+ query_test_with_failures(self, _metadata, 0, 10, removed, 1);
+
+ ASSERT_EQ(0, renameat(self->digest_lists_dirfd, "tlv-digest_list6",
+ self->base_dirfd, "tlv-digest_list6"));
+
+ removed[1] = 6;
+
+ query_test_with_failures(self, _metadata, 0, 10, removed, 2);
+
+ ASSERT_EQ(0, renameat(self->base_dirfd, "tlv-digest_list6",
+ self->digest_lists_dirfd, "tlv-digest_list6"));
+
+ query_test_with_failures(self, _metadata, 0, 10, removed, 1);
+
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd, "tlv-digest_list10",
+ HASH_ALGO_SHA1, 10, 1, TLV_NO_FAILURE));
+
+ query_test_with_failures(self, _metadata, 0, 11, removed, 1);
+}
+
+static void _check_verif_data(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata,
+ char *digest_list_filename, int num,
+ enum hash_algo algo, bool check_dir)
+{
+ char digest_list_filename_kernel[NAME_MAX + 1];
+ char cmd[1024], number[20];
+ u8 digest[MAX_DIGEST_SIZE] = { 0 };
+ char digest_str[MAX_DIGEST_SIZE * 2 + 1] = { 0 };
+ int len, cmd_len;
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/file",
+ commands_str[DIGEST_CACHE_GET], self->base_dir);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ /*
+ * If a directory digest cache was requested, we need to do a lookup,
+ * to make the kernel module retrieve verification data from the digest
+ * cache of the directory entry.
+ */
+ if (check_dir) {
+ *(u32 *)digest = num;
+
+ bin2hex(digest_str, digest, hash_digest_size[algo]);
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/file|%s:%s",
+ commands_str[DIGEST_CACHE_LOOKUP],
+ self->base_dir, hash_algo_name[algo],
+ digest_str);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+ }
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_SET_VERIF],
+ verifs_str[VERIF_FILENAMES]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ ASSERT_LT(0, read(self->kernfd, digest_list_filename_kernel,
+ sizeof(digest_list_filename_kernel)));
+ ASSERT_EQ(0, strcmp(digest_list_filename, digest_list_filename_kernel));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_SET_VERIF],
+ verifs_str[VERIF_NUMBER]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ len = read(self->kernfd, number, sizeof(number) - 1);
+ ASSERT_LT(0, len);
+ number[len] = '\0';
+ ASSERT_EQ(num, atoi(number));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s",
+ commands_str[DIGEST_CACHE_PUT]);
+ write(self->kernfd, cmd, cmd_len);
+}
+
+static void check_verif_data(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata)
+{
+ char digest_list_filename[NAME_MAX + 1];
+ char cmd[1024];
+ int i, cmd_len;
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_ENABLE_VERIF],
+ verifs_str[VERIF_FILENAMES]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_ENABLE_VERIF],
+ verifs_str[VERIF_NUMBER]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ /*
+ * Reverse order is intentional, so that directory entries are created
+ * in the opposite order as when they are searched (when prefetching is
+ * requested).
+ */
+ for (i = 10; i >= 0; i--) {
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd,
+ digest_list_filename, HASH_ALGO_SHA1,
+ i, 1, TLV_NO_FAILURE));
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file",
+ digest_list_filename));
+
+ _check_verif_data(self, _metadata, digest_list_filename, i,
+ HASH_ALGO_SHA1, false);
+
+ ASSERT_EQ(0, unlinkat(self->base_dirfd, "file", 0));
+ }
+
+ ASSERT_EQ(0, create_file(self->base_dirfd, "file", NULL));
+
+ for (i = 0; i < 11; i++) {
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ _check_verif_data(self, _metadata, digest_list_filename, i,
+ HASH_ALGO_SHA1, true);
+ }
+
+ ASSERT_EQ(0, unlinkat(self->base_dirfd, "file", 0));
+}
+
+/*
+ * Verify that the correct verification data can be retrieved from the digest
+ * caches (without digest list prefetching).
+ */
+TEST_F(shared_data, verif_data_no_prefetch)
+{
+ check_verif_data(self, _metadata);
+}
+
+/*
+ * Verify that the correct verification data can be retrieved from the digest
+ * caches (with digest list prefetching).
+ */
+TEST_F(shared_data, verif_data_prefetch)
+{
+ ASSERT_EQ(0, lsetxattr(self->base_dir, XATTR_NAME_DIG_PREFETCH,
+ "1", 1, 0));
+
+ check_verif_data(self, _metadata);
+}
+
+static void check_prefetch_list(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata,
+ int start_number, int end_number)
+{
+ char digest_list_filename[NAME_MAX + 1], filename[NAME_MAX + 1];
+ char digest_lists[1024], digest_lists_kernel[1024] = { 0 };
+ char cmd[1024];
+ int i, cmd_len;
+
+ snprintf(filename, sizeof(filename), "file%d", end_number);
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", end_number, end_number);
+ ASSERT_EQ(0, create_file(self->base_dirfd, filename,
+ digest_list_filename));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/%s",
+ commands_str[DIGEST_CACHE_GET], self->base_dir,
+ filename);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ ASSERT_LT(0, read(self->kernfd, digest_lists, sizeof(digest_lists)));
+
+ for (i = start_number; i <= end_number; i++) {
+ if (digest_lists_kernel[0])
+ strcat(digest_lists_kernel, ",");
+
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ strcat(digest_lists_kernel, digest_list_filename);
+ }
+
+ ASSERT_EQ(0, strcmp(digest_lists, digest_lists_kernel));
+
+ ASSERT_EQ(0, unlinkat(self->base_dirfd, filename, 0));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s",
+ commands_str[DIGEST_CACHE_PUT]);
+ write(self->kernfd, cmd, cmd_len);
+}
+
+static void check_prefetch_list_async(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata)
+{
+ char digest_list_filename[NAME_MAX + 1], filename[NAME_MAX + 1];
+ char digest_lists[1024], digest_lists_kernel[1024] = { 0 };
+ char cmd[1024];
+ int i, cmd_len;
+
+ for (i = 0; i < NUM_DIGEST_LISTS_PREFETCH; i++) {
+ snprintf(filename, sizeof(filename), "file%d",
+ NUM_DIGEST_LISTS_PREFETCH - 1 - i);
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ ASSERT_EQ(0, create_file(self->base_dirfd, filename,
+ digest_list_filename));
+ }
+
+ /* Do batch of get/put to test the kernel for concurrent requests. */
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s/file|%d|%d",
+ commands_str[DIGEST_CACHE_GET_PUT_ASYNC],
+ self->base_dir, 0, NUM_DIGEST_LISTS_PREFETCH - 1);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ ASSERT_LT(0, read(self->kernfd, digest_lists, sizeof(digest_lists)));
+
+ for (i = 0; i < NUM_DIGEST_LISTS_PREFETCH; i++) {
+ if (digest_lists_kernel[0])
+ strcat(digest_lists_kernel, ",");
+
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ strcat(digest_lists_kernel, digest_list_filename);
+ }
+
+ ASSERT_EQ(0, strcmp(digest_lists, digest_lists_kernel));
+}
+
+static void prepare_prefetch(struct _test_data_shared_data *self,
+ struct __test_metadata *_metadata)
+{
+ char digest_list_filename[NAME_MAX + 1];
+ char cmd[1024];
+ int i, cmd_len;
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_ENABLE_VERIF],
+ verifs_str[VERIF_PREFETCH]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s|%s",
+ commands_str[DIGEST_CACHE_SET_VERIF],
+ verifs_str[VERIF_PREFETCH]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+
+ for (i = NUM_DIGEST_LISTS_PREFETCH - 1; i >= 0; i--) {
+ snprintf(digest_list_filename, sizeof(digest_list_filename),
+ "%d-tlv-digest_list%d", i, i);
+ ASSERT_EQ(0, gen_tlv_list(self->digest_lists_dirfd,
+ digest_list_filename, HASH_ALGO_SHA1,
+ i, 1, TLV_NO_FAILURE));
+ }
+
+ ASSERT_EQ(0, fsetxattr(self->digest_lists_dirfd,
+ XATTR_NAME_DIG_PREFETCH, "1", 1, 0));
+}
+
+/*
+ * Verify that digest lists are prefetched when requested, in the correct order
+ * (synchronous version).
+ */
+TEST_F(shared_data, prefetch_sync)
+{
+ char cmd[1024];
+ int i, cmd_len;
+
+ prepare_prefetch(self, _metadata);
+
+ for (i = 2; i < NUM_DIGEST_LISTS_PREFETCH; i += 3) {
+ check_prefetch_list(self, _metadata, i - 2, i);
+
+ cmd_len = snprintf(cmd, sizeof(cmd), "%s",
+ commands_str[DIGEST_CACHE_RESET_PREFETCH_BUF]);
+ ASSERT_EQ(cmd_len, write(self->kernfd, cmd, cmd_len));
+ }
+}
+
+/*
+ * Verify that digest lists are prefetched when requested, in the correct order
+ * (asynchronous version).
+ */
+TEST_F(shared_data, prefetch_async)
+{
+ prepare_prefetch(self, _metadata);
+
+ check_prefetch_list_async(self, _metadata);
+}
+
+TEST_HARNESS_MAIN
diff --git a/tools/testing/selftests/digest_cache/common.c b/tools/testing/selftests/digest_cache/common.c
new file mode 100644
index 000000000000..8e82b318ab50
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/common.c
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Add common code for testing the digest_cache LSM.
+ */
+
+#include "common.h"
+
+const char *commands_str[DIGEST_CACHE__LAST] = {
+ [DIGEST_CACHE_GET] = "get",
+ [DIGEST_CACHE_LOOKUP] = "lookup",
+ [DIGEST_CACHE_PUT] = "put",
+ [DIGEST_CACHE_ENABLE_VERIF] = "enable_verif",
+ [DIGEST_CACHE_DISABLE_VERIF] = "disable_verif",
+ [DIGEST_CACHE_SET_VERIF] = "set_verif",
+ [DIGEST_CACHE_GET_PUT_ASYNC] = "get_put_async",
+ [DIGEST_CACHE_RESET_PREFETCH_BUF] = "reset_prefetch_buf",
+};
+
+const char *const hash_algo_name[HASH_ALGO__LAST] = {
+ [HASH_ALGO_MD4] = "md4",
+ [HASH_ALGO_MD5] = "md5",
+ [HASH_ALGO_SHA1] = "sha1",
+ [HASH_ALGO_RIPE_MD_160] = "rmd160",
+ [HASH_ALGO_SHA256] = "sha256",
+ [HASH_ALGO_SHA384] = "sha384",
+ [HASH_ALGO_SHA512] = "sha512",
+ [HASH_ALGO_SHA224] = "sha224",
+ [HASH_ALGO_RIPE_MD_128] = "rmd128",
+ [HASH_ALGO_RIPE_MD_256] = "rmd256",
+ [HASH_ALGO_RIPE_MD_320] = "rmd320",
+ [HASH_ALGO_WP_256] = "wp256",
+ [HASH_ALGO_WP_384] = "wp384",
+ [HASH_ALGO_WP_512] = "wp512",
+ [HASH_ALGO_TGR_128] = "tgr128",
+ [HASH_ALGO_TGR_160] = "tgr160",
+ [HASH_ALGO_TGR_192] = "tgr192",
+ [HASH_ALGO_SM3_256] = "sm3",
+ [HASH_ALGO_STREEBOG_256] = "streebog256",
+ [HASH_ALGO_STREEBOG_512] = "streebog512",
+ [HASH_ALGO_SHA3_256] = "sha3-256",
+ [HASH_ALGO_SHA3_384] = "sha3-384",
+ [HASH_ALGO_SHA3_512] = "sha3-512",
+};
+
+const int hash_digest_size[HASH_ALGO__LAST] = {
+ [HASH_ALGO_MD4] = MD5_DIGEST_SIZE,
+ [HASH_ALGO_MD5] = MD5_DIGEST_SIZE,
+ [HASH_ALGO_SHA1] = SHA1_DIGEST_SIZE,
+ [HASH_ALGO_RIPE_MD_160] = RMD160_DIGEST_SIZE,
+ [HASH_ALGO_SHA256] = SHA256_DIGEST_SIZE,
+ [HASH_ALGO_SHA384] = SHA384_DIGEST_SIZE,
+ [HASH_ALGO_SHA512] = SHA512_DIGEST_SIZE,
+ [HASH_ALGO_SHA224] = SHA224_DIGEST_SIZE,
+ [HASH_ALGO_RIPE_MD_128] = RMD128_DIGEST_SIZE,
+ [HASH_ALGO_RIPE_MD_256] = RMD256_DIGEST_SIZE,
+ [HASH_ALGO_RIPE_MD_320] = RMD320_DIGEST_SIZE,
+ [HASH_ALGO_WP_256] = WP256_DIGEST_SIZE,
+ [HASH_ALGO_WP_384] = WP384_DIGEST_SIZE,
+ [HASH_ALGO_WP_512] = WP512_DIGEST_SIZE,
+ [HASH_ALGO_TGR_128] = TGR128_DIGEST_SIZE,
+ [HASH_ALGO_TGR_160] = TGR160_DIGEST_SIZE,
+ [HASH_ALGO_TGR_192] = TGR192_DIGEST_SIZE,
+ [HASH_ALGO_SM3_256] = SM3256_DIGEST_SIZE,
+ [HASH_ALGO_STREEBOG_256] = STREEBOG256_DIGEST_SIZE,
+ [HASH_ALGO_STREEBOG_512] = STREEBOG512_DIGEST_SIZE,
+ [HASH_ALGO_SHA3_256] = SHA3_256_DIGEST_SIZE,
+ [HASH_ALGO_SHA3_384] = SHA3_384_DIGEST_SIZE,
+ [HASH_ALGO_SHA3_512] = SHA3_512_DIGEST_SIZE,
+};
+
+const char *verifs_str[] = {
+ [VERIF_FILENAMES] = "filenames",
+ [VERIF_NUMBER] = "number",
+ [VERIF_PREFETCH] = "prefetch",
+};
diff --git a/tools/testing/selftests/digest_cache/common.h b/tools/testing/selftests/digest_cache/common.h
new file mode 100644
index 000000000000..1fb4ba96d028
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/common.h
@@ -0,0 +1,131 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Header of common.c.
+ */
+
+#ifndef _COMMON_H
+#define _COMMON_H
+#include <linux/types.h>
+
+#include "../../../../include/uapi/linux/hash_info.h"
+
+#define MD5_DIGEST_SIZE 16
+#define SHA1_DIGEST_SIZE 20
+#define RMD160_DIGEST_SIZE 20
+#define SHA256_DIGEST_SIZE 32
+#define SHA384_DIGEST_SIZE 48
+#define SHA512_DIGEST_SIZE 64
+#define SHA224_DIGEST_SIZE 28
+#define RMD128_DIGEST_SIZE 16
+#define RMD256_DIGEST_SIZE 32
+#define RMD320_DIGEST_SIZE 40
+#define WP256_DIGEST_SIZE 32
+#define WP384_DIGEST_SIZE 48
+#define WP512_DIGEST_SIZE 64
+#define TGR128_DIGEST_SIZE 16
+#define TGR160_DIGEST_SIZE 20
+#define TGR192_DIGEST_SIZE 24
+#define SM3256_DIGEST_SIZE 32
+#define STREEBOG256_DIGEST_SIZE 32
+#define STREEBOG512_DIGEST_SIZE 64
+#define SHA3_224_DIGEST_SIZE (224 / 8)
+#define SHA3_256_DIGEST_SIZE (256 / 8)
+#define SHA3_384_DIGEST_SIZE (384 / 8)
+#define SHA3_512_DIGEST_SIZE (512 / 8)
+
+#define DIGEST_CACHE_TEST_INTERFACE "/sys/kernel/security/digest_cache_test"
+#define DIGEST_CACHE_PATH_INTERFACE "/sys/kernel/security/digest_cache_path"
+#define MAX_DIGEST_SIZE 64
+
+#define RPMTAG_FILEDIGESTS 1035
+#define RPMTAG_FILEDIGESTALGO 5011
+
+#define RPM_INT32_TYPE 4
+#define RPM_STRING_ARRAY_TYPE 8
+
+#define MAX_WORKS 21
+
+typedef __u8 u8;
+typedef __u16 u16;
+typedef __u32 u32;
+typedef __s32 s32;
+typedef __u64 u64;
+
+enum commands {
+ DIGEST_CACHE_GET, // args: <path>
+ DIGEST_CACHE_LOOKUP, // args: <algo>|<digest>
+ DIGEST_CACHE_PUT, // args:
+ DIGEST_CACHE_ENABLE_VERIF, // args: <verif name>
+ DIGEST_CACHE_DISABLE_VERIF, // args: <verif name>
+ DIGEST_CACHE_SET_VERIF, // args: <verif name>
+ DIGEST_CACHE_GET_PUT_ASYNC, // args: <path>|<start#>|<end#>
+ DIGEST_CACHE_RESET_PREFETCH_BUF,// args:
+ DIGEST_CACHE__LAST,
+};
+
+enum tlv_failures { TLV_NO_FAILURE,
+ TLV_FAILURE_ALGO_LEN,
+ TLV_FAILURE_HDR_LEN,
+ TLV_FAILURE_ALGO_MISMATCH,
+ TLV_FAILURE_NUM_DIGESTS,
+ TLV_FAILURE__LAST
+};
+
+enum rpm_failures { RPM_NO_FAILURE,
+ RPM_FAILURE_WRONG_MAGIC,
+ RPM_FAILURE_BAD_DATA_OFFSET,
+ RPM_FAILURE_WRONG_TAGS,
+ RPM_FAILURE_WRONG_DIGEST_COUNT,
+ RPM_FAILURE_DIGEST_WRONG_TYPE,
+ RPM_FAILURE__LAST
+};
+
+enum file_changes { FILE_WRITE,
+ FILE_TRUNCATE,
+ FILE_UNLINK,
+ FILE_RENAME,
+ FILE_CHANGE__LAST
+};
+
+enum VERIFS {
+ VERIF_FILENAMES,
+ VERIF_NUMBER,
+ VERIF_PREFETCH,
+ VERIF__LAST
+};
+
+enum pgp_algos {
+ DIGEST_ALGO_MD5 = 1,
+ DIGEST_ALGO_SHA1 = 2,
+ DIGEST_ALGO_RMD160 = 3,
+ /* 4, 5, 6, and 7 are reserved. */
+ DIGEST_ALGO_SHA256 = 8,
+ DIGEST_ALGO_SHA384 = 9,
+ DIGEST_ALGO_SHA512 = 10,
+ DIGEST_ALGO_SHA224 = 11,
+};
+
+struct rpm_hdr {
+ u32 magic;
+ u32 reserved;
+ u32 tags;
+ u32 datasize;
+} __attribute__ ((__packed__));
+
+struct rpm_entryinfo {
+ s32 tag;
+ u32 type;
+ s32 offset;
+ u32 count;
+} __attribute__ ((__packed__));
+
+extern const char *commands_str[DIGEST_CACHE__LAST];
+extern const char *const hash_algo_name[HASH_ALGO__LAST];
+extern const int hash_digest_size[HASH_ALGO__LAST];
+extern const char *verifs_str[VERIF__LAST];
+
+#endif /* _COMMON_H */
diff --git a/tools/testing/selftests/digest_cache/common_user.c b/tools/testing/selftests/digest_cache/common_user.c
new file mode 100644
index 000000000000..1bacadad6b6a
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/common_user.c
@@ -0,0 +1,47 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Add common code in user space for testing the digest_cache LSM.
+ */
+
+#include <stddef.h>
+
+#include "common_user.h"
+
+static const char hex_asc[] = "0123456789abcdef";
+
+#define hex_asc_lo(x) hex_asc[((x) & 0x0f)]
+#define hex_asc_hi(x) hex_asc[((x) & 0xf0) >> 4]
+
+const enum hash_algo pgp_algo_mapping[DIGEST_ALGO_SHA224 + 1] = {
+ [DIGEST_ALGO_MD5] = HASH_ALGO_MD5,
+ [DIGEST_ALGO_SHA1] = HASH_ALGO_SHA1,
+ [DIGEST_ALGO_RMD160] = HASH_ALGO_RIPE_MD_160,
+ [4] = HASH_ALGO__LAST,
+ [5] = HASH_ALGO__LAST,
+ [6] = HASH_ALGO__LAST,
+ [7] = HASH_ALGO__LAST,
+ [DIGEST_ALGO_SHA256] = HASH_ALGO_SHA256,
+ [DIGEST_ALGO_SHA384] = HASH_ALGO_SHA384,
+ [DIGEST_ALGO_SHA512] = HASH_ALGO_SHA512,
+ [DIGEST_ALGO_SHA224] = HASH_ALGO_SHA224,
+};
+
+static inline char *hex_byte_pack(char *buf, unsigned char byte)
+{
+ *buf++ = hex_asc_hi(byte);
+ *buf++ = hex_asc_lo(byte);
+ return buf;
+}
+
+char *bin2hex(char *dst, const void *src, size_t count)
+{
+ const unsigned char *_src = src;
+
+ while (count--)
+ dst = hex_byte_pack(dst, *_src++);
+ return dst;
+}
diff --git a/tools/testing/selftests/digest_cache/common_user.h b/tools/testing/selftests/digest_cache/common_user.h
new file mode 100644
index 000000000000..4eef52cc5c27
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/common_user.h
@@ -0,0 +1,17 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Header of common_user.c.
+ */
+
+#include <linux/types.h>
+#include <stddef.h>
+
+#include "common.h"
+
+extern const enum hash_algo pgp_algo_mapping[DIGEST_ALGO_SHA224 + 1];
+
+char *bin2hex(char *dst, const void *src, size_t count);
diff --git a/tools/testing/selftests/digest_cache/config b/tools/testing/selftests/digest_cache/config
new file mode 100644
index 000000000000..075a06cc4f8e
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/config
@@ -0,0 +1 @@
+CONFIG_SECURITY_DIGEST_CACHE=y
diff --git a/tools/testing/selftests/digest_cache/generators.c b/tools/testing/selftests/digest_cache/generators.c
new file mode 100644
index 000000000000..c7791a3589f2
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/generators.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Generate digest lists for testing.
+ */
+
+#include <stddef.h>
+#include <fcntl.h>
+#include <errno.h>
+#include <limits.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/xattr.h>
+#include <asm/byteorder.h>
+
+#include "generators.h"
+#include "../../../../include/uapi/linux/hash_info.h"
+#include "../../../../include/uapi/linux/xattr.h"
+#include "../../../../include/uapi/linux/tlv_digest_list.h"
+#include "../../../../include/uapi/linux/tlv_parser.h"
+
+int gen_tlv_list(int temp_dirfd, char *digest_list_filename,
+ enum hash_algo algo, int start_number, int num_digests,
+ enum tlv_failures failure)
+{
+ u64 _algo = __cpu_to_be64(algo);
+ u8 digest[MAX_DIGEST_SIZE] = { 0 };
+ int digest_len = hash_digest_size[algo];
+ int digest_len_to_copy = digest_len;
+ int ret, fd, i;
+
+ struct tlv_data_entry algo_entry = {
+ .field = __cpu_to_be64(DIGEST_LIST_ALGO),
+ .length = __cpu_to_be64(sizeof(_algo)),
+ };
+
+ struct tlv_data_entry entry_digest = {
+ .field = __cpu_to_be64(DIGEST_LIST_ENTRY_DIGEST),
+ .length = __cpu_to_be64(digest_len),
+ };
+
+ struct tlv_hdr entry_hdr = {
+ .data_type = __cpu_to_be64(DIGEST_LIST_ENTRY_DATA),
+ ._reserved = 0,
+ .num_entries = __cpu_to_be64(1),
+ .total_len = __cpu_to_be64(sizeof(entry_digest) + digest_len),
+ };
+
+ struct tlv_data_entry entry_entry = {
+ .field = __cpu_to_be64(DIGEST_LIST_ENTRY),
+ .length = __cpu_to_be64(sizeof(entry_hdr) +
+ __be64_to_cpu(entry_hdr.total_len)),
+ };
+
+ struct tlv_hdr hdr = {
+ .data_type = __cpu_to_be64(DIGEST_LIST_FILE),
+ ._reserved = 0,
+ .num_entries = __cpu_to_be64(1 + num_digests),
+ .total_len = __cpu_to_be64(sizeof(algo_entry) +
+ __be64_to_cpu(algo_entry.length) +
+ num_digests * (sizeof(entry_entry) +
+ __be64_to_cpu(entry_entry.length)))
+ };
+
+ switch (failure) {
+ case TLV_FAILURE_ALGO_LEN:
+ algo_entry.length = algo_entry.length / 2;
+ break;
+ case TLV_FAILURE_HDR_LEN:
+ hdr.total_len--;
+ break;
+ case TLV_FAILURE_ALGO_MISMATCH:
+ _algo = __cpu_to_be64(algo - 1);
+ break;
+ case TLV_FAILURE_NUM_DIGESTS:
+ num_digests = 0;
+ break;
+ default:
+ break;
+ }
+
+ fd = openat(temp_dirfd, digest_list_filename,
+ O_WRONLY | O_CREAT | O_TRUNC, 0600);
+ if (fd == -1)
+ return -errno;
+
+ ret = write(fd, (u8 *)&hdr, sizeof(hdr));
+ if (ret != sizeof(hdr))
+ return -errno;
+
+ ret = write(fd, (u8 *)&algo_entry, sizeof(algo_entry));
+ if (ret != sizeof(algo_entry))
+ return -errno;
+
+ ret = write(fd, (u8 *)&_algo, sizeof(_algo));
+ if (ret != sizeof(_algo))
+ return -errno;
+
+ *(u32 *)digest = start_number;
+
+ for (i = 0; i < num_digests; i++) {
+ ret = write(fd, (u8 *)&entry_entry, sizeof(entry_entry));
+ if (ret != sizeof(entry_entry))
+ return -errno;
+
+ ret = write(fd, (u8 *)&entry_hdr, sizeof(entry_hdr));
+ if (ret != sizeof(entry_hdr))
+ return -errno;
+
+ ret = write(fd, (u8 *)&entry_digest, sizeof(entry_digest));
+ if (ret != sizeof(entry_digest))
+ return -errno;
+
+ ret = write(fd, digest, digest_len_to_copy);
+ if (ret != digest_len_to_copy)
+ return -errno;
+
+ (*(u32 *)digest)++;
+ }
+
+ close(fd);
+ return 0;
+}
+
+int gen_rpm_list(int temp_dirfd, char *digest_list_filename,
+ enum hash_algo algo, enum pgp_algos pgp_algo, int start_number,
+ int num_digests, enum rpm_failures failure)
+{
+ u32 _pgp_algo = __cpu_to_be32(pgp_algo);
+ u8 digest[MAX_DIGEST_SIZE] = { 0 };
+ char digest_str[MAX_DIGEST_SIZE * 2 + 1];
+ struct rpm_hdr hdr;
+ struct rpm_entryinfo algo_entry, digest_entry;
+ int digest_len = hash_digest_size[algo];
+ int ret, fd, d_len, i;
+
+ d_len = hash_digest_size[algo] * 2 + 1;
+
+ hdr.magic = __cpu_to_be32(0x8eade801);
+ hdr.reserved = 0;
+ hdr.tags = __cpu_to_be32(1);
+
+ /*
+ * Skip the algo section, to ensure that the parser recognizes MD5 as
+ * the default hash algorithm.
+ */
+ if (algo != HASH_ALGO_MD5)
+ hdr.tags = __cpu_to_be32(2);
+
+ hdr.datasize = __cpu_to_be32(d_len * num_digests);
+
+ if (algo != HASH_ALGO_MD5)
+ hdr.datasize = __cpu_to_be32(sizeof(u32) + d_len * num_digests);
+
+ digest_entry.tag = __cpu_to_be32(RPMTAG_FILEDIGESTS);
+ digest_entry.type = __cpu_to_be32(RPM_STRING_ARRAY_TYPE);
+ digest_entry.offset = 0;
+ digest_entry.count = __cpu_to_be32(num_digests);
+
+ algo_entry.tag = __cpu_to_be32(RPMTAG_FILEDIGESTALGO);
+ algo_entry.type = __cpu_to_be32(RPM_INT32_TYPE);
+ algo_entry.offset = __cpu_to_be32(d_len * num_digests);
+ algo_entry.count = __cpu_to_be32(1);
+
+ switch (failure) {
+ case RPM_FAILURE_WRONG_MAGIC:
+ hdr.magic++;
+ break;
+ case RPM_FAILURE_BAD_DATA_OFFSET:
+ algo_entry.offset = __cpu_to_be32(UINT_MAX);
+ break;
+ case RPM_FAILURE_WRONG_TAGS:
+ hdr.tags = __cpu_to_be32(2 + 10);
+ break;
+ case RPM_FAILURE_WRONG_DIGEST_COUNT:
+ /* We need to go beyond the algorithm, to fail. */
+ digest_entry.count = __cpu_to_be32(num_digests + 5);
+ break;
+ case RPM_FAILURE_DIGEST_WRONG_TYPE:
+ digest_entry.type = __cpu_to_be32(RPM_INT32_TYPE);
+ break;
+ default:
+ break;
+ }
+
+ fd = openat(temp_dirfd, digest_list_filename,
+ O_WRONLY | O_CREAT | O_TRUNC, 0600);
+ if (fd == -1)
+ return -errno;
+
+ ret = write(fd, (u8 *)&hdr, sizeof(hdr));
+ if (ret != sizeof(hdr))
+ return -errno;
+
+ if (algo != HASH_ALGO_MD5) {
+ ret = write(fd, (u8 *)&algo_entry, sizeof(algo_entry));
+ if (ret != sizeof(algo_entry))
+ return -errno;
+ }
+
+ ret = write(fd, (u8 *)&digest_entry, sizeof(digest_entry));
+ if (ret != sizeof(digest_entry))
+ return -errno;
+
+ *(u32 *)digest = start_number;
+
+ for (i = 0; i < num_digests; i++) {
+ bin2hex(digest_str, digest, digest_len);
+
+ ret = write(fd, (u8 *)digest_str, d_len);
+ if (ret != d_len)
+ return -errno;
+
+ (*(u32 *)digest)++;
+ }
+
+ if (algo != HASH_ALGO_MD5) {
+ ret = write(fd, (u8 *)&_pgp_algo, sizeof(_pgp_algo));
+ if (ret != sizeof(_pgp_algo))
+ return -errno;
+ }
+
+ close(fd);
+ return 0;
+}
+
+int create_file(int temp_dirfd, char *filename, char *digest_list_filename)
+{
+ int ret = 0, fd;
+
+ fd = openat(temp_dirfd, filename, O_WRONLY | O_CREAT | O_TRUNC, 0600);
+ if (fd == -1)
+ return -errno;
+
+ if (!digest_list_filename)
+ goto out;
+
+ ret = fsetxattr(fd, XATTR_NAME_DIGEST_LIST, digest_list_filename,
+ strlen(digest_list_filename) + 1, 0);
+ if (ret == -1)
+ ret = -errno;
+out:
+ close(fd);
+ return ret;
+}
diff --git a/tools/testing/selftests/digest_cache/generators.h b/tools/testing/selftests/digest_cache/generators.h
new file mode 100644
index 000000000000..1c83e531b799
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/generators.h
@@ -0,0 +1,19 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Header of generators.c.
+ */
+
+#include "common.h"
+#include "common_user.h"
+
+int gen_tlv_list(int temp_dirfd, char *digest_list_filename,
+ enum hash_algo algo, int start_number, int num_digests,
+ enum tlv_failures failure);
+int gen_rpm_list(int temp_dirfd, char *digest_list_filename,
+ enum hash_algo algo, enum pgp_algos pgp_algo, int start_number,
+ int num_digests, enum rpm_failures failure);
+int create_file(int temp_dirfd, char *filename, char *digest_list_filename);
diff --git a/tools/testing/selftests/digest_cache/testmod/Makefile b/tools/testing/selftests/digest_cache/testmod/Makefile
new file mode 100644
index 000000000000..1ba1c7f08658
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/testmod/Makefile
@@ -0,0 +1,16 @@
+KDIR ?= ../../../../..
+
+MODULES = digest_cache_kern.ko
+
+obj-m += digest_cache_kern.o
+
+digest_cache_kern-y := kern.o ../common.o
+
+all:
+ +$(Q)$(MAKE) -C $(KDIR) M=$$PWD modules
+
+clean:
+ +$(Q)$(MAKE) -C $(KDIR) M=$$PWD clean
+
+install: all
+ +$(Q)$(MAKE) -C $(KDIR) M=$$PWD modules_install
diff --git a/tools/testing/selftests/digest_cache/testmod/kern.c b/tools/testing/selftests/digest_cache/testmod/kern.c
new file mode 100644
index 000000000000..618b008c9c5d
--- /dev/null
+++ b/tools/testing/selftests/digest_cache/testmod/kern.c
@@ -0,0 +1,499 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2023-2024 Huawei Technologies Duesseldorf GmbH
+ *
+ * Author: Roberto Sassu <[email protected]>
+ *
+ * Implement the kernel module to interact with the digest_cache LSM.
+ */
+
+#define pr_fmt(fmt) "DIGEST CACHE TEST: "fmt
+#include <linux/module.h>
+#include <linux/namei.h>
+#include <linux/security.h>
+#include <linux/dynamic_debug.h>
+#include <linux/digest_cache.h>
+#include <linux/kprobes.h>
+#include <linux/cpu.h>
+#include <linux/kernel_read_file.h>
+#include <crypto/hash_info.h>
+
+#include "../common.h"
+
+struct verif {
+ int (*update)(struct file *file);
+ ssize_t (*read)(struct file *file, char __user *buf, size_t datalen,
+ loff_t *ppos);
+ bool enabled;
+};
+
+struct read_work {
+ struct work_struct work;
+ char *path_str;
+ int ret;
+};
+
+static struct dentry *test;
+static struct digest_cache *digest_cache;
+static digest_cache_found_t found;
+static int cur_verif_index;
+static u8 prefetch_buf[4096];
+static struct read_work w[MAX_WORKS];
+
+static int filenames_update(struct file *file)
+{
+ char *filename = (char *)file->f_path.dentry->d_name.name;
+
+ return digest_cache_verif_set(file, "filenames", filename,
+ strlen(filename) + 1);
+}
+
+static int number_update(struct file *file)
+{
+ const char *filename = file_dentry(file)->d_name.name;
+ size_t filename_len = strlen(filename);
+ u64 number = U64_MAX;
+ int ret;
+
+ while (filename_len) {
+ if (filename[filename_len - 1] < '0' ||
+ filename[filename_len - 1] > '9')
+ break;
+
+ filename_len--;
+ }
+
+ ret = kstrtoull(filename + filename_len, 10, &number);
+ if (ret < 0) {
+ pr_debug("Failed to convert filename %s into number\n",
+ file_dentry(file)->d_name.name);
+ return ret;
+ }
+
+ return digest_cache_verif_set(file, "number", &number, sizeof(number));
+}
+
+static ssize_t filenames_read(struct file *file, char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ loff_t _ppos = 0;
+ char *filenames_list;
+
+ filenames_list = digest_cache_verif_get(found ?
+ digest_cache_from_found_t(found) : digest_cache,
+ verifs_str[VERIF_FILENAMES]);
+ if (!filenames_list)
+ return -ENOENT;
+
+ return simple_read_from_buffer(buf, datalen, &_ppos, filenames_list,
+ strlen(filenames_list) + 1);
+}
+
+static ssize_t number_read(struct file *file, char __user *buf, size_t datalen,
+ loff_t *ppos)
+{
+ loff_t _ppos = 0;
+ u64 *number;
+ char temp[20];
+ ssize_t len;
+
+ number = digest_cache_verif_get(found ?
+ digest_cache_from_found_t(found) :
+ digest_cache, verifs_str[VERIF_NUMBER]);
+ if (!number)
+ return -ENOENT;
+
+ len = snprintf(temp, sizeof(temp), "%llu", *number);
+
+ return simple_read_from_buffer(buf, datalen, &_ppos, temp, len);
+}
+
+static int prefetch_update(struct file *file)
+{
+ char *filename = (char *)file->f_path.dentry->d_name.name;
+ char *start_ptr = prefetch_buf, *end_ptr;
+ int ret;
+
+ ret = digest_cache_verif_set(file, "probe_digest_cache", "1", 1);
+ if (!ret) {
+ /* Don't include duplicates of requested digest lists. */
+ while ((end_ptr = strchrnul(start_ptr, ','))) {
+ if (end_ptr > start_ptr &&
+ !strncmp(start_ptr, filename, end_ptr - start_ptr))
+ return 0;
+
+ if (!*end_ptr)
+ break;
+
+ start_ptr = end_ptr + 1;
+ }
+ }
+
+ if (prefetch_buf[0])
+ strlcat(prefetch_buf, ",", sizeof(prefetch_buf));
+
+ strlcat(prefetch_buf, filename, sizeof(prefetch_buf));
+ return 0;
+}
+
+static ssize_t prefetch_read(struct file *file, char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ loff_t _ppos = 0;
+
+ return simple_read_from_buffer(buf, datalen, &_ppos, prefetch_buf,
+ strlen(prefetch_buf) + 1);
+}
+
+static struct verif verifs_methods[] = {
+ [VERIF_FILENAMES] = { .update = filenames_update,
+ .read = filenames_read },
+ [VERIF_NUMBER] = { .update = number_update, .read = number_read },
+ [VERIF_PREFETCH] = { .update = prefetch_update, .read = prefetch_read },
+};
+
+static void digest_cache_get_put_work(struct work_struct *work)
+{
+ struct read_work *w = container_of(work, struct read_work, work);
+ struct digest_cache *digest_cache;
+ struct path path;
+
+ w->ret = kern_path(w->path_str, 0, &path);
+ if (w->ret < 0)
+ return;
+
+ digest_cache = digest_cache_get(path.dentry);
+
+ path_put(&path);
+
+ if (!digest_cache) {
+ w->ret = -ENOENT;
+ return;
+ }
+
+ digest_cache_put(digest_cache);
+ w->ret = 0;
+}
+
+static int digest_cache_get_put_async(char *path_str, int start_number,
+ int end_number)
+{
+ int ret = 0, i;
+
+ cpus_read_lock();
+ for (i = start_number; i <= end_number; i++) {
+ w[i].path_str = kasprintf(GFP_KERNEL, "%s%u", path_str, i);
+ if (!w[i].path_str) {
+ ret = -ENOMEM;
+ break;
+ }
+
+ INIT_WORK_ONSTACK(&w[i].work, digest_cache_get_put_work);
+ schedule_work_on(i % num_online_cpus(), &w[i].work);
+ }
+ cpus_read_unlock();
+
+ for (i = start_number; i <= end_number; i++) {
+ if (!w[i].path_str)
+ continue;
+
+ flush_work(&w[i].work);
+ destroy_work_on_stack(&w[i].work);
+ kfree(w[i].path_str);
+ w[i].path_str = NULL;
+ if (!ret)
+ ret = w[i].ret;
+ }
+
+ return ret;
+}
+
+static ssize_t write_request(struct file *file, const char __user *buf,
+ size_t datalen, loff_t *ppos)
+{
+ char *data, *data_ptr, *cmd_str, *path_str, *algo_str, *digest_str;
+ char *verif_name_str, *start_number_str, *end_number_str;
+ u8 digest[64];
+ struct path path;
+ int ret, cmd, algo, verif_index, start_number, end_number;
+
+ data = memdup_user_nul(buf, datalen);
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ data_ptr = data;
+
+ cmd_str = strsep(&data_ptr, "|");
+ if (!cmd_str) {
+ pr_debug("No command\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ cmd = match_string(commands_str, DIGEST_CACHE__LAST, cmd_str);
+ if (cmd < 0) {
+ pr_err("Unknown command %s\n", cmd_str);
+ ret = -ENOENT;
+ goto out;
+ }
+
+ switch (cmd) {
+ case DIGEST_CACHE_GET:
+ found = 0UL;
+
+ path_str = strsep(&data_ptr, "|");
+ if (!path_str) {
+ pr_debug("No path\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = kern_path(path_str, 0, &path);
+ if (ret < 0) {
+ pr_debug("Cannot find file %s\n", path_str);
+ goto out;
+ }
+
+ if (digest_cache) {
+ pr_debug("Digest cache exists, doing a put\n");
+ digest_cache_put(digest_cache);
+ }
+
+ digest_cache = digest_cache_get(path.dentry);
+ ret = digest_cache ? 0 : -ENOENT;
+ pr_debug("digest cache get %s, ret: %d\n", path_str, ret);
+ path_put(&path);
+ break;
+ case DIGEST_CACHE_LOOKUP:
+ if (!digest_cache) {
+ pr_debug("No digest cache\n");
+ ret = -ENOENT;
+ goto out;
+ }
+
+ path_str = strsep(&data_ptr, "|");
+ if (!path_str) {
+ pr_debug("No path\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ algo_str = strsep(&data_ptr, ":");
+ digest_str = data_ptr;
+
+ if (!algo_str || !digest_str) {
+ pr_debug("No algo or digest\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ algo = match_string(hash_algo_name, HASH_ALGO__LAST, algo_str);
+ if (algo < 0) {
+ pr_err("Unknown algorithm %s", algo_str);
+ ret = -ENOENT;
+ goto out;
+ }
+
+ ret = hex2bin(digest, digest_str, hash_digest_size[algo]);
+ if (ret < 0) {
+ pr_debug("Invalid digest %s\n", digest_str);
+ goto out;
+ }
+
+ ret = kern_path(path_str, 0, &path);
+ if (ret < 0) {
+ pr_debug("Cannot find file %s\n", path_str);
+ goto out;
+ }
+
+ ret = -ENOENT;
+
+ found = digest_cache_lookup(path.dentry, digest_cache, digest,
+ algo);
+ path_put(&path);
+ if (found)
+ ret = 0;
+
+ pr_debug("%s:%s lookup %s, ret: %d\n", algo_str, digest_str,
+ path_str, ret);
+ break;
+ case DIGEST_CACHE_PUT:
+ if (digest_cache) {
+ digest_cache_put(digest_cache);
+ digest_cache = NULL;
+ }
+ ret = 0;
+ pr_debug("digest cache put, ret: %d\n", ret);
+ break;
+ case DIGEST_CACHE_ENABLE_VERIF:
+ case DIGEST_CACHE_DISABLE_VERIF:
+ memset(prefetch_buf, 0, sizeof(prefetch_buf));
+ fallthrough;
+ case DIGEST_CACHE_SET_VERIF:
+ verif_name_str = strsep(&data_ptr, "|");
+ if (!verif_name_str) {
+ pr_debug("No verifier name\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ verif_index = match_string(verifs_str, ARRAY_SIZE(verifs_str),
+ verif_name_str);
+ if (verif_index < 0) {
+ pr_err("Unknown verifier name %s\n", verif_name_str);
+ ret = -ENOENT;
+ goto out;
+ }
+
+ if (cmd == DIGEST_CACHE_ENABLE_VERIF)
+ verifs_methods[verif_index].enabled = true;
+ else if (cmd == DIGEST_CACHE_DISABLE_VERIF)
+ verifs_methods[verif_index].enabled = false;
+ else
+ cur_verif_index = verif_index;
+
+ ret = 0;
+ pr_debug("digest cache %s %s, ret: %d\n", cmd_str,
+ verif_name_str, ret);
+ break;
+ case DIGEST_CACHE_GET_PUT_ASYNC:
+ path_str = strsep(&data_ptr, "|");
+ if (!path_str) {
+ pr_debug("No path\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ start_number_str = strsep(&data_ptr, "|");
+ if (!start_number_str) {
+ pr_debug("No start number\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = kstrtoint(start_number_str, 10, &start_number);
+ if (ret < 0) {
+ pr_debug("Invalid start number %s\n", start_number_str);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ end_number_str = strsep(&data_ptr, "|");
+ if (!end_number_str) {
+ pr_debug("No end number\n");
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = kstrtoint(end_number_str, 10, &end_number);
+ if (ret < 0) {
+ pr_debug("Invalid end number %s\n", end_number_str);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ if (end_number - start_number >= MAX_WORKS) {
+ pr_debug("Too many works (%d), max %d\n",
+ end_number - start_number, MAX_WORKS - 1);
+ ret = -EINVAL;
+ goto out;
+ }
+
+ ret = digest_cache_get_put_async(path_str, start_number,
+ end_number);
+ pr_debug("digest cache %s on %s, start: %d, end: %d, ret: %d\n",
+ cmd_str, path_str, start_number, end_number, ret);
+ break;
+ case DIGEST_CACHE_RESET_PREFETCH_BUF:
+ memset(prefetch_buf, 0, sizeof(prefetch_buf));
+ pr_debug("digest cache %s\n", cmd_str);
+ ret = 0;
+ break;
+ default:
+ ret = -EINVAL;
+ break;
+ }
+out:
+ kfree(data);
+ return ret ?: datalen;
+}
+
+static ssize_t read_request(struct file *file, char __user *buf, size_t datalen,
+ loff_t *ppos)
+{
+ return verifs_methods[cur_verif_index].read(file, buf, datalen, ppos);
+}
+
+static const struct file_operations digest_cache_test_ops = {
+ .open = generic_file_open,
+ .write = write_request,
+ .read = read_request,
+ .llseek = generic_file_llseek,
+};
+
+static int __kprobes kernel_post_read_file_hook(struct kprobe *p,
+ struct pt_regs *regs)
+{
+#ifdef CONFIG_HAVE_DYNAMIC_FTRACE_WITH_ARGS
+ struct file *file = (struct file *)regs_get_kernel_argument(regs, 0);
+ enum kernel_read_file_id id = regs_get_kernel_argument(regs, 3);
+#else
+ struct file *file = NULL;
+ enum kernel_read_file_id id = READING_UNKNOWN;
+#endif
+ int ret, i;
+
+ if (id != READING_DIGEST_LIST)
+ return 0;
+
+ for (i = 0; i < ARRAY_SIZE(verifs_methods); i++) {
+ if (!verifs_methods[i].enabled)
+ continue;
+
+ ret = verifs_methods[i].update(file);
+ if (ret < 0)
+ return 0;
+ }
+
+ return 0;
+}
+
+static struct kprobe kp = {
+ .symbol_name = "security_kernel_post_read_file",
+};
+
+static int __init digest_cache_test_init(void)
+{
+ int ret;
+
+ kp.pre_handler = kernel_post_read_file_hook;
+
+ ret = register_kprobe(&kp);
+ if (ret < 0) {
+ pr_err("register_kprobe failed, returned %d\n", ret);
+ return ret;
+ }
+
+ test = securityfs_create_file("digest_cache_test", 0660, NULL, NULL,
+ &digest_cache_test_ops);
+ if (IS_ERR(test)) {
+ unregister_kprobe(&kp);
+ return PTR_ERR(test);
+ }
+
+ return 0;
+}
+
+static void __exit digest_cache_test_fini(void)
+{
+ if (digest_cache)
+ digest_cache_put(digest_cache);
+
+ securityfs_remove(test);
+ unregister_kprobe(&kp);
+ pr_debug("kprobe at %p unregistered\n", kp.addr);
+}
+
+module_init(digest_cache_test_init);
+module_exit(digest_cache_test_fini);
+MODULE_LICENSE("GPL");
--
2.34.1
From: Roberto Sassu <[email protected]>
Add the documentation of the digest_cache LSM in Documentation/security.
Signed-off-by: Roberto Sassu <[email protected]>
---
Documentation/security/digest_cache.rst | 900 ++++++++++++++++++++++++
Documentation/security/index.rst | 1 +
MAINTAINERS | 1 +
3 files changed, 902 insertions(+)
create mode 100644 Documentation/security/digest_cache.rst
diff --git a/Documentation/security/digest_cache.rst b/Documentation/security/digest_cache.rst
new file mode 100644
index 000000000000..6a492e23495c
--- /dev/null
+++ b/Documentation/security/digest_cache.rst
@@ -0,0 +1,900 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================
+Digest_cache LSM
+================
+
+Introduction
+============
+
+Integrity detection and protection has long been a desirable feature, to
+reach a large user base and mitigate the risk of flaws in the software and
+attacks.
+
+However, while solutions exist, they struggle to reach the large user base,
+due to requiring higher than desired constraints on performance,
+flexibility and configurability, that only security conscious people are
+willing to accept.
+
+This is where the new digest_cache LSM comes into play, it offers
+additional support for new and existing integrity solutions, to make them
+faster and easier to deploy.
+
+
+Motivation
+==========
+
+The digest_cache LSM helps to address two important shortcomings of the
+Integrity Measurement Architecture (IMA): predictability of the Platform
+Configuration Registers (PCRs), and the provisioning of reference values to
+compare the calculated file digest against.
+
+Remote attestation, according to Trusted Computing Group (TCG)
+specifications, is done by replicating the PCR extend operation in
+software with the digests in the event log (in this case the IMA
+measurement list), and by comparing the obtained value with the PCR value
+signed by the TPM with the quote operation.
+
+Due to how the extend operation is performed, if measurements are done in
+a different order, the final PCR value will be different. That means that
+if measurements are done in parallel, there is no way to predict what the
+final PCR value will be, making impossible to seal data to a PCR value. If
+the PCR value was predictable, a system could for example prove its
+integrity by unsealing and using its private key, without sending every
+time the full list of measurements.
+
+Provisioning reference values for file digests is also a difficult task.
+The solution so far was to add file signatures to RPM packages, and
+possibly to DEB packages, so that IMA can verify them. While this undoubtly
+works, it also requires Linux distribution vendors to support the feature
+by rebuilding all their packages, and eventually extending their PKI to
+perform the additional signatures. It could also require developers extra
+work to deal with the additional data.
+
+On the other hand, since often packages carry the file digests themselves,
+it won't be actually needed to add file signatures. If the kernel was able
+to extract the file digests by itself, all the tasks mentioned above for
+the Linux distribution vendors won't be needed too. All current and past
+Linux distributions can be easily retrofitted to enable IMA appraisal with
+the file digests from the packages.
+
+Narrowing down the scope of a package parser to only extract specific
+information makes it small enough to accurately verify that it cannot harm
+the kernel. In fact, the parsers included with the digest_cache LSM have
+been verified with the formal verification tool Frama-C, albeit with a
+limited buffer size (the verification time grows considerably with bigger
+buffer sizes). The parsers with the Frama-C assertions are available here:
+
+https://github.com/robertosassu/rpm-formal/
+
+Frama-C asserts that the parsers don't read beyond their assigned buffer
+for any byte combination.
+
+An additional mitigation against corrupted digest lists consists in
+verifying the signature of the package first, before attempting to extract
+the file digests.
+
+
+Solution
+========
+
+The digest_cache LSM can help IMA to extend a PCR in a deterministic way.
+If IMA knows that a file comes from a Linux distribution, it can measure
+files in a different way: measure the list of digests coming from the
+distribution (e.g. RPM package headers), and subsequently measure a file if
+it is not found in that list.
+
+If the system executes known files, it does not matter in which order they
+are executed, because the PCR is not extended. That however means that the
+lists of digests must be measured in a deterministic way. The digest_cache
+LSM has a prefetching mechanism to make this happen, consisting in
+sequentially reading digest lists in a directory until it finds the
+requested one.
+
+The resulting IMA measurement list however has a disadvantage: it does not
+tell to remote verifiers whether files with digest in the measured digest
+lists have been accessed or not and when. Also the IMA measurement list
+would change after a software update.
+
+The digest_cache LSM can also help IMA for appraisal. Currently, IMA has
+to evaluate the signature of each file individually, and expects that the
+Linux vendors include those signatures together with the files in the
+packages.
+
+With the digest_cache LSM, IMA can simply lookup in the list of digests
+extracted from package headers, once the signature of those headers has
+been verified. The same approach can be followed by other LSMs, such as
+Integrity Policy Enforcement (IPE).
+
+
+Design
+======
+
+Digest cache
+------------
+
+The digest_cache LSM collects digests from various sources (called digest
+lists), and stores them in kernel memory, in a set of hash tables forming a
+digest cache. Extracted digests can be used as reference values for
+integrity verification of file content or metadata.
+
+A digest cache has three types of references: in the inode security blob of
+the digest list the digest cache was created from (dig_owner field); in the
+security blob of the inodes for which the digest cache is requested
+(dig_user field); a reference returned by digest_cache_get().
+
+References are released with digest_cache_put(), in the first two cases
+when inodes are evicted from memory, in the last case when that function is
+explicitly called. Obtaining a digest cache reference means that the digest
+cache remains valid and cannot be freed until releasing it and until the
+total number of references (stored in the digest cache) becomes zero.
+
+When digest_cache_get() is called on an inode to compare its digest with
+a reference value, the digest_cache LSM knows which digest cache to get
+from the new security.digest_list xattr added to that inode, which contains
+the file name of the desired digest list digests will be extracted from.
+
+All digest lists are expected to be in the same directory, defined in the
+kernel config, and modifiable at run-time through securityfs. When the
+digest_cache LSM reads the security.digest_list xattr, it uses its value as
+last path component, appended to the default path (unless the default path
+is a file). If an inode does not have that xattr, the default path is
+considered as the final destination.
+
+The default path can be either a file or a directory. If it is a file, the
+digest_cache LSM always uses the same digest cache from that file to verify
+all inodes (the xattr, if present, is ignored). If it is a directory, and
+the inode to verify does not have the xattr, the digest_cache LSM iterates
+and looks up on the digest caches created from each directory entry.
+
+Digest caches are created on demand, only when digest_cache_get() is
+called. The first time a digest cache is requested, the digest_cache LSM
+creates it and sets its reference in the dig_owner and dig_user fields of
+the respective inode security blobs. On the next requests, the previously
+set reference is returned, after incrementing the reference count.
+
+Since there might be multiple digest_cache_get() calls for the same inode,
+or for different inodes pointing to the same digest list, dig_owner_mutex
+and dig_user_mutex have been introduced to protect the check and assignment
+of the digest cache reference in the inode security blob.
+
+Contenders that didn't get the lock also have to wait until the digest
+cache is fully instantiated (when the bit INIT_IN_PROGRESS is cleared).
+Dig_owner_mutex cannot be used for waiting on the instantiation to avoid
+lock inversion with the inode lock for directories.
+
+
+Verification data
+-----------------
+
+The digest_cache LSM can support other LSMs in their decisions of granting
+access to file content and metadata.
+
+However, the information alone about whether a digest was found in a digest
+cache might not be sufficient, because for example those LSMs wouldn't know
+whether the digest cache itself was created from authentic data.
+
+Digest_cache_verif_set() lets the same LSMs (or a chosen integrity
+provider) evaluate the digest list being read during the creation of the
+digest cache, by implementing the kernel_post_read_file LSM hook, and lets
+them attach their verification data to that digest cache.
+
+Space is reserved in the file descriptor security blob for the digest cache
+pointer. Digest_cache_to_file_sec() sets that pointer before calling
+kernel_read_file() in digest_cache_populate(), and
+digest_cache_from_file_sec() retrieves the pointer back from the file
+descriptor passed by LSMs with digest_cache_verif_set().
+
+Multiple providers are supported, in the event there are multiple
+integrity LSMs active. Each provider should also provide an unique verifier
+ID as an argument to digest_cache_verif_set(), so that verification data
+can be distinguished.
+
+A caller of digest_cache_get() can retrieve back the verification data by
+calling digest_cache_verif_get() and passing a digest cache pointer and the
+desired verifier ID.
+
+Since directory digest caches are not populated themselves, LSMs have to do
+a lookup first to get the digest cache containing the digest, call
+digest_cache_from_found_t() to convert the returned digest_cache_found_t
+type to a digest cache pointer, and pass that to digest_cache_verif_get().
+
+
+Directories
+-----------
+
+In the environments where xattrs are not available (e.g. in the initial ram
+disk), the digest_cache LSM cannot precisely determine which digest list in
+a directory contains the desired reference digest. However, although
+slower, it would be desirable to search the digest in all digest lists of
+that directory.
+
+This done in two steps. When a digest cache is being created,
+digest_cache_create() invokes digest_cache_dir_create(), to generate the
+list of current directory entries. Entries are placed in the list in
+ascending order by the <seq num> if prepended to the file name, or at the
+end of the list if not.
+
+The resulting digest cache has the IS_DIR bit set, to distinguish it from
+the digest caches created from regular files.
+
+Second, when a digest is searched in a directory digest cache,
+digest_cache_lookup() invokes digest_cache_dir_lookup_digest() to
+iteratively search that digest in each directory entry generated by
+digest_cache_dir_create().
+
+That list is stable, even if new files are added or deleted from that
+directory. In that case, the digest_cache LSM will invalidate the digest
+cache, forcing next callers of digest_cache_get() to get a new directory
+digest cache with the updated list of directory entries.
+
+If the current directory entry does not have a digest cache reference,
+digest_cache_dir_lookup_digest() invokes digest_cache_create() to create a
+new digest cache for that entry. In either case,
+digest_cache_dir_lookup_digest() calls then digest_cache_htable_lookup()
+with the new/existing digest cache to search the digest.
+
+The iteration stops when the digest is found. In that case,
+digest_cache_dir_lookup_digest() returns the digest cache reference of the
+current directory entry as the digest_cache_found_t type, so that callers
+of digest_cache_lookup() don't mistakenly try to call digest_cache_put()
+with that reference.
+
+This new reference type will be used to retrieve information about the
+digest cache containing the digest, which is not known in advance until the
+digest search is performed.
+
+The order of the list of directory entries influences the speed of the
+digest search. A search terminates faster if less digest caches have to be
+created. One way to optimize it could be to order the list of digest lists
+in the same way of when they are requested at boot.
+
+Finally, digest_cache_dir_free() releases the digest cache references
+stored in the list of directory entries, and frees the list itself.
+
+
+Prefetching
+-----------
+
+A desirable goal when doing integrity measurements is that they are done
+always in the same order across boots, so that the resulting PCR value
+becomes predictable and suitable for sealing policies. However, due to
+parallel execution of system services at boot, a deterministic order of
+measurements is difficult to achieve.
+
+The digest_cache LSM is not exempted from this issue. Under the assumption
+that only the digest list is measured, and file measurements are omitted if
+their digest is found in that digest list, a PCR can be predictable only if
+all files belong to the same digest list. Otherwise, it will still be
+unpredictable, since files accessed in a non-deterministic order will cause
+digest lists to be measured in a non-deterministic order too.
+
+The prefetching mechanism overcomes this issue by searching a digest list
+file name in digest_list_dir_lookup_filename() among the entries of the
+linked list built by digest_cache_dir_create(). If the file name does not
+match, it reads the digest list to trigger its measurement. Otherwise, it
+also creates a digest cache and returns that to the caller.
+
+Prefetching needs to be explicitly enabled by setting the new
+security.dig_prefetch xattr to 1 in the directory containing the digest
+lists. The newly introduced function digest_cache_prefetch_requested()
+checks first if the DIR_PREFETCH bit is set in dig_owner, otherwise it
+reads the xattr. digest_cache_create() sets DIR_PREFETCH in dig_owner, if
+prefetching is enabled, before declaring the digest cache as initialized.
+
+
+Tracking changes
+----------------
+
+The digest_cache LSM registers to five LSM hooks, file_open, path_truncate,
+file_release, inode_unlink and inode_rename, to monitor digest lists and
+directory modifications.
+
+If an action affects a digest list or the parent directory, these hooks
+call digest_cache_reset() to set the RESET bit on the digest cache. This
+will cause next calls to digest_cache_get() and digest_cache_create() to
+respectively put and clear dig_user and dig_owner, and request a new
+digest cache.
+
+That does not affect other users of the old digest cache, since that one
+remains valid as long as the reference count is greater than zero. However,
+they can explicitly call the new function digest_cache_was_reset(), to
+check if the RESET bit was set on the digest cache reference they hold.
+
+Recreating a file digest cache means reading the digest list again and
+extracting the digests. Recreating a directory digest cache, instead, does
+not mean recreating the digest cache for directory entries, since those
+digest caches are likely already stored in the inode security blob. It
+would happen however for new files.
+
+File digest cache reset is done on file_open, when a digest list is opened
+for write, path_truncate, when a digest list is truncated (there is no
+inode_truncate, file_truncate does not catch operations through the
+truncate() system call), inode_unlink, when a digest list is removed, and
+inode_rename when a digest list is renamed.
+
+Directory digest cache reset is done on file_release, when a digest list is
+written in the digest list directory, on inode_unlink, when a digest list
+is deleted from that directory, and finally on inode_rename, when a digest
+list is moved to/from that directory.
+
+With the exception of file_release, which will always be executed (cannot
+be denied), the other LSM hooks are not optimal, since the digest_cache LSM
+does not know whether or not the operation will be allowed also by other
+LSMs. If the operation is denied, the digest_cache LSM would do an
+unnecessary reset.
+
+
+Data structures and API
+=======================
+
+Data structures
+---------------
+
+These are the data structures defined and used internally by the
+digest_cache LSM.
+
+.. kernel-doc:: security/digest_cache/internal.h
+
+
+Public API
+----------
+
+This API is meant to be used by users of the digest_cache LSM.
+
+.. kernel-doc:: include/linux/digest_cache.h
+ :identifiers: digest_cache_found_t
+ digest_cache_from_found_t
+
+.. kernel-doc:: security/digest_cache/main.c
+ :identifiers: digest_cache_get digest_cache_put
+
+.. kernel-doc:: security/digest_cache/htable.c
+ :identifiers: digest_cache_lookup
+
+.. kernel-doc:: security/digest_cache/verif.c
+ :identifiers: digest_cache_verif_set digest_cache_verif_get
+
+.. kernel-doc:: security/digest_cache/reset.c
+ :identifiers: digest_cache_was_reset
+
+
+Parser API
+----------
+
+This API is meant to be used by digest list parsers.
+
+.. kernel-doc:: security/digest_cache/htable.c
+ :identifiers: digest_cache_htable_init
+ digest_cache_htable_add
+ digest_cache_htable_lookup
+
+
+Digest List Formats
+===================
+
+tlv
+---
+
+The Type-Length-Value (TLV) format was chosen for its extensibility.
+Additional fields can be added without breaking compatibility with old
+versions of the parser.
+
+The layout of a tlv digest list is the following::
+
+ [header: DIGEST_LIST_FILE, num fields, total len]
+ [field: DIGEST_LIST_ALGO, length, value]
+ [field: DIGEST_LIST_ENTRY#1, length, value (below)]
+ |- [header: DIGEST_LIST_ENTRY_DATA, num fields, total len]
+ |- [DIGEST_LIST_ENTRY_DIGEST#1, length, file digest]
+ |- [DIGEST_LIST_ENTRY_PATH#1, length, file path]
+ [field: DIGEST_LIST_ENTRY#N, length, value (below)]
+ |- [header: DIGEST_LIST_ENTRY_DATA, num fields, total len]
+ |- [DIGEST_LIST_ENTRY_DIGEST#N, length, file digest]
+ |- [DIGEST_LIST_ENTRY_PATH#N, length, file path]
+
+DIGEST_LIST_ALGO is a field to specify the algorithm of the file digest.
+DIGEST_LIST_ENTRY is a nested TLV structure with the following fields:
+DIGEST_LIST_ENTRY_DIGEST contains the file digest; DIGEST_LIST_ENTRY_PATH
+contains the file path.
+
+
+rpm
+---
+
+The rpm digest list is basically a subset of the RPM package header.
+Its format is::
+
+ [RPM magic number]
+ [RPMTAG_IMMUTABLE]
+
+RPMTAG_IMMUTABLE is a section of the full RPM header containing the part
+of the header that was signed, and whose signature is stored in the
+RPMTAG_RSAHEADER section.
+
+
+Appended Signature
+------------------
+
+Digest lists can have a module-style appended signature, that can be used
+for appraisal with IMA. The signature type can be PKCS#7, as for kernel
+modules, or a different type.
+
+
+History
+=======
+
+The original name of this work was IMA Digest Lists, which was somehow
+considered too invasive. The code was moved to a separate component named
+DIGLIM (DIGest Lists Integrity Module), with the purpose of removing the
+complexity away of IMA, and also adding the possibility of using it with
+other kernel components (e.g. Integrity Policy Enforcement, or IPE).
+
+The design changed significantly, so DIGLIM was renamed to digest_cache
+LSM, as the name better reflects what the new component does.
+
+Since it was originally proposed, in 2017, this work grew up a lot thanks
+to various comments/suggestions. It became integrally part of the openEuler
+distribution since end of 2020.
+
+The most important difference between the old the current version is moving
+from a centralized repository of file digests to a per-package repository.
+This significantly reduces the memory pressure, since digest lists are
+loaded into kernel memory only when they are actually needed. Also, file
+digests are automatically unloaded from kernel memory at the same time
+inodes are evicted from memory during reclamation.
+
+
+Performance
+===========
+
+System specification
+--------------------
+
+The tests have been performed on a Fedora 38 virtual machine with 4 cores
+(AMD EPYC-Rome, no hyperthreading), 4 GB of RAM, no TPM/TPM passthrough/
+emulated. The QEMU process has been pinned to 4 real CPU cores and its
+priority was set to -20.
+
+
+Benchmark tool
+--------------
+
+The digest_cache LSM has been tested with an ad-hoc benchmark tool that
+creates 20000 files with a random size up to 100 bytes and randomly adds
+their digest to one of 303 digest lists. The number of digest lists has
+been derived from the ratio (66) digests/packages (124174/1883) found in
+the testing virtual machine (hence, 20000/66 = 303). IMA signatures have
+been done with ECDSA NIST P-384.
+
+The benchmark tool then creates a list of 20000 files to be accessed,
+randomly chosen (there can be duplicates). This is necessary to make the
+results reproducible across reboots (by always replaying the same
+operations). The benchmark reads (sequentially and in parallel) the files
+from the list 2 times, flushing the kernel caches before each read.
+
+Each test has been performed 5 times, and the average value is taken.
+
+
+Purpose of the benchmark
+------------------------
+
+The purpose of the benchmark is to show the performance difference of IMA
+between the current behavior, and by using the digest_cache LSM.
+
+
+IMA measurement policy: no cache
+--------------------------------
+
+.. code-block:: bash
+
+ measure func=FILE_CHECK fowner=2001 pcr=12
+
+
+IMA measurement policy: cache
+-----------------------------
+
+.. code-block:: bash
+
+ measure func=DIGEST_LIST_CHECK pcr=12
+ measure func=FILE_CHECK fowner=2001 digest_cache=content pcr=12
+
+
+IMA Measurement Results
+-----------------------
+
+Sequential
+~~~~~~~~~~
+
+This test was performed reading files sequentially, and waiting for the
+current read to terminate before beginning a new one.
+
+::
+
+ +-------+------------------------+-----------+
+ | meas. | time no/p/vTPM (sec.) | slab (KB) |
+ +--------------------+-------+------------------------+-----------+
+ | no cache | 12313 | 33.65 / 102.51 / 47.13 | 84170 |
+ +--------------------+-------+------------------------+-----------+
+ | cache, no prefetch | 304 | 34.04 / 33.32 / 33.09 | 81159 |
+ +--------------------+-------+------------------------+-----------+
+ | cache, prefetch | 304 | 34.02 / 33.31 / 33.15 | 81122 |
+ +--------------------+-------+------------------------+-----------+
+
+The table shows that 12313 measurements (boot_aggregate + files) have been
+made without the digest cache, and 304 with the digest cache
+(boot_aggregate + digest lists). Consequently, the memory occupation
+without the cache is higher due to the higher number of measurements.
+
+Not surprisingly, for the same reason, also the test time is significantly
+higher without the digest cache when the physical or virtual TPM is used.
+
+In terms of pure performance, first number in the third column, it can be
+seen that there are not really performance differences between using or not
+using the digest cache.
+
+Prefetching does not add overhead, also because digest lists were ordered
+according to their appearance in the IMA measurement list (which minimize
+the digest lists to prefetch).
+
+
+Parallel
+~~~~~~~~
+
+This test was performed reading files in parallel, not waiting for the
+current read to terminate.
+
+::
+
+ +-------+-----------------------+-----------+
+ | meas. | time no/p/vTPM (sec.) | slab (KB) |
+ +--------------------+-------+-----------------------+-----------+
+ | no cache | 12313 | 14.08 / 79.09 / 22.70 | 85138 |
+ +--------------------+-------+-----------------------+-----------+
+ | cache, no prefetch | 304 | 14.44 / 15.11 / 14.96 | 85777 |
+ +--------------------+-------+-----------------------+-----------+
+ | cache, prefetch | 304 | 14.30 / 15.41 / 14.40 | 83294 |
+ +--------------------+-------+-----------------------+-----------+
+
+Also in this case, the physical TPM causes the biggest delay especially
+without digest cache, where a higher number of measurements need to be
+extended in the TPM.
+
+The digest_cache LSM does not introduce a noticeable overhead in all
+scenarios.
+
+
+IMA appraisal policy: no cache
+------------------------------
+
+.. code-block:: bash
+
+ appraise func=FILE_CHECK fowner=2001
+
+
+IMA appraisal policy: cache
+---------------------------
+
+.. code-block:: bash
+
+ appraise func=DIGEST_LIST_CHECK
+ appraise func=FILE_CHECK fowner=2001 digest_cache=content
+
+
+IMA Appraisal Results
+---------------------
+
+Sequential
+~~~~~~~~~~
+
+This test was performed reading files sequentially, and waiting for the
+current read to terminate before beginning a new one.
+
+::
+
+ +-------------+-------------+-----------+
+ | files | time (sec.) | slab (KB) |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (ECDSA sig) | 12312 | 96.74 | 78827 |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (cache) | 12312 + 303 | 33.09 | 80854 |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (cache, prefetch) | 12312 + 303 | 33.42 | 81050 |
+ +----------------------------+-------------+-------------+-----------+
+
+This test shows a huge performance difference from verifying the signature
+of 12312 files as opposed to just verifying the signature of 303 digest
+lists, and looking up the digest of the files being read.
+
+There are some differences in terms of memory occupation, which is quite
+expected due to the fact that we have to take into account the digest
+caches loaded in memory, while with the standard appraisal they don't
+exist.
+
+
+Parallel
+~~~~~~~~
+
+This test was performed reading files in parallel, not waiting for the
+current read to terminate.
+
+::
+
+ +-------------+-------------+-----------+
+ | files | time (sec.) | slab (KB) |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (ECDSA sig) | 12312 | 27.68 | 80596 |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (cache) | 12313 + 303 | 14.96 | 80778 |
+ +----------------------------+-------------+-------------+-----------+
+ | appraise (cache, prefetch) | 12313 + 303 | 14.78 | 83354 |
+ +----------------------------+-------------+-------------+-----------+
+
+The difference is less marked when performing the read in parallel. Also,
+more memory seems to be occupied in the prefetch case.
+
+
+How to Test
+===========
+
+Additional patches need to be applied to the kernel.
+
+The patch to introduce the file_release LSM hook:
+
+https://lore.kernel.org/linux-integrity/[email protected]/
+
+The patch set to use the PGP keys from the Linux distributions for
+verifying the RPM header signatures:
+
+https://lore.kernel.org/linux-integrity/[email protected]/
+
+The same URL contains two GNUPG patches to be applied to the user space
+program.
+
+The patch set to use the digest_cache LSM from IMA:
+
+https://github.com/robertosassu/linux/commits/digest_cache-lsm-v3-ima/
+
+First, it is necessary to install the kernel headers in usr/ in the kernel
+source directory:
+
+.. code-block:: bash
+
+ $ make headers_install
+
+After, it is necessary to copy the new kernel headers (tlv_parser.h,
+uasym_parser.h, tlv_digest_list.h) from usr/include/linux in the kernel
+source directory to /usr/include/linux.
+
+Then, gpg must be rebuilt with the additional patches to convert the PGP
+keys of the Linux distribution to the new user asymmetric key format:
+
+.. code-block:: bash
+
+ $ gpg --conv-kernel <path of PGP key> >> certs/uasym_keys.bin
+
+This embeds the converted keys in the kernel image.
+
+Finally, the following kernel options must be enabled:
+
+.. code-block:: bash
+
+ CONFIG_SECURITY_DIGEST_CACHE=y
+ CONFIG_UASYM_KEYS_SIGS=y
+ CONFIG_UASYM_PRELOAD_PUBLIC_KEYS=y
+
+and the kernel must be rebuilt with the patches applied. After reboot, it
+is necessary to build and install the digest list tools downloadable from:
+
+https://github.com/linux-integrity/digest-cache-tools
+
+and to execute (as root):
+
+.. code-block:: bash
+
+ # manage_digest_lists -o gen -d /etc/digest_lists -i rpmdb -f rpm
+
+The new gpg must also be installed in the system, as it will be used to
+convert the PGP signatures of the RPM headers to the user asymmetric key
+format.
+
+It is recommended to create an additional digest list with the following
+files, by creating a file named ``list`` with the content:
+
+.. code-block:: bash
+
+ /usr/bin/manage_digest_lists
+ /usr/lib64/libgen-tlv-list.so
+ /usr/lib64/libgen-rpm-list.so
+ /usr/lib64/libparse-rpm-list.so
+ /usr/lib64/libparse-tlv-list.so
+
+Then, to create the digest list, it is sufficient to execute:
+
+.. code-block:: bash
+
+ # manage_digest_lists -i list -L -d /etc/digest_lists -o gen -f tlv
+
+Also, a digest list must be created for the modified gpg binary:
+
+.. code-block:: bash
+
+ # manage_digest_lists -i /usr/bin/gpg -d /etc/digest_lists -o gen -f tlv
+
+If appraisal is enabled and in enforcing mode, it is necessary to sign the
+new digest lists, with the sign-file tool in the scripts/ directory of the
+kernel sources:
+
+.. code-block:: bash
+
+ # scripts/sign-file sha256 certs/signing_key.pem certs/signing_key.pem /etc/digest_lists/tlv-list
+ # scripts/sign-file sha256 certs/signing_key.pem certs/signing_key.pem /etc/digest_lists/tlv-gpg
+
+The final step is to add security.digest_list to each file with:
+
+.. code-block:: bash
+
+ # manage_digest_lists -i /etc/digest_lists -o add-xattr
+
+After that, it is possible to test the digest_cache LSM with the following
+policy written to /etc/ima/ima-policy:
+
+.. code-block:: bash
+
+ measure func=DIGEST_LIST_CHECK template=ima-modsig pcr=12
+ dont_measure fsmagic=0x01021994
+ measure func=BPRM_CHECK digest_cache=content pcr=12
+ measure func=MMAP_CHECK digest_cache=content pcr=12
+
+Tmpfs is excluded for now, until memfd is properly handled. The reason why
+the DIGEST_LIST_CHECK rule is before the dont_measure is that otherwise
+digest lists in the initial ram disk won't be processed.
+
+Before loading the policy, it is possible to enable dynamic debug to see
+which operations are done by the digest_cache LSM:
+
+.. code-block:: bash
+
+ # echo "file security/digest_cache/* +p" > /sys/kernel/debug/dynamic_debug/control
+
+Alternatively, the same strings can be set as value of the dyndbg= option
+in the kernel command line.
+
+A preliminary test, before booting the system with the new policy, is to
+supply the policy to IMA in the current system with:
+
+.. code-block:: bash
+
+ # cat /etc/ima/ima-policy > /sys/kernel/security/ima/policy
+
+After executing some commands, it can be seen if the digest_cache LSM is
+working by checking the IMA measurement list. If there are only digest
+lists, it means that everything is working properly, and the system can be
+rebooted. The instructions have been tested on a Fedora 38 OS.
+
+After boot, it is possible to check the content of the measurement list:
+
+.. code-block:: bash
+
+ # cat /sys/kernel/security/ima/ascii_runtime_measurements
+
+
+At this point, it is possible to enable the prefetching mechanism to make
+the PCR predictable. The virtual machine must be configured with a TPM
+(Emulated).
+
+To enable the prefetching mechanism, it is necessary to set
+security.dig_prefetch to '1' for the /etc/digest_lists directory:
+
+.. code-block:: bash
+
+ # setfattr -n security.dig_prefetch -v "1" /etc/digest_lists
+
+The final step is to reorder digest lists to be in the same order in which
+they appear in the IMA measurement list.
+
+This can be done by executing the command:
+
+.. code-block:: bash
+
+ # manage_digest_lists -i /sys/kernel/security/ima/ascii_runtime_measurements -d /etc/digest_lists -o add-seqnum
+
+Since we renamed the digest lists, we need to update security.digest_list
+too:
+
+.. code-block:: bash
+
+ # manage_digest_lists -i /etc/digest_lists -o add-xattr
+
+By rebooting several times, and just logging in (to execute the same
+commands during each boot), it is possible to compare the PCR 12, and see
+that it is always the same. That of course works only if the TPM is reset
+at each boot (e.g. if the virtual machine has a virtual TPM) or if the code
+is tested in the host environment.
+
+.. code-block:: bash
+
+ # cat /sys/devices/LNXSYSTM:00/LNXSYBUS:00/MSFT0101:00/tpm/tpm0/pcr-sha256/12
+
+The last step is to test IMA appraisal. This can be done by adding the
+following lines to /etc/ima/ima-policy:
+
+.. code-block:: bash
+
+ appraise func=DIGEST_LIST_CHECK appraise_type=imasig|modsig
+ dont_appraise fsmagic=0x01021994
+ appraise func=BPRM_CHECK digest_cache=content
+ appraise func=MMAP_CHECK digest_cache=content
+
+The following test is to ensure that IMA prevents the execution of unknown
+files:
+
+.. code-block:: bash
+
+ # cp -a /bin/cat .
+ # ./cat
+
+That will work. But not on the modified binary:
+
+.. code-block:: bash
+
+ # echo 1 >> cat
+ # ./cat
+ -bash: ./cat: Permission denied
+
+Execution will be denied, and a new entry in the measurement list will
+appear (it would be probably ok to not add that entry, as access to the
+file was denied):
+
+.. code-block:: bash
+
+ 12 50b5a68bea0776a84eef6725f17ce474756e51c0 ima-ng sha256:15e1efee080fe54f5d7404af7e913de01671e745ce55215d89f3d6521d3884f0 /root/cat
+
+Finally, it is possible to test the shrinking of the digest cache, by
+forcing the kernel to evict inodes from memory:
+
+.. code-block:: bash
+
+ # echo 3 > /proc/sys/vm/drop_caches
+
+If dynamic debug was enabled, the kernel log should have messages like:
+
+.. code-block:: bash
+
+ [ 313.032536] DIGEST CACHE: Removed digest sha256:102900208eef27b766380135906d431dba87edaa7ec6aa72e6ebd3dd67f3a97b from digest list /etc/digest_lists/rpm-libseccomp-2.5.3-4.fc38.x86_64
+
+Optionally, it is possible to test IMA measurement/appraisal from the very
+beginning of the boot process, for now by including all digest lists and the
+IMA policy in the initial ram disk. In the future, there will be a dracut
+patch for ``dracut_install`` to select only the necessary digest lists.
+
+This can be simply done by executing:
+
+.. code-block:: bash
+
+ # dracut -f -I " /etc/ima/ima-policy " -i /etc/digest_lists/ /etc/digest_lists/ --nostrip --kver <your kernel version>
+
+The --nostrip option is particularly important. If debugging symbols are
+stripped from the binary, its digest no longer matches with the one from
+the package, causing access denied.
+
+The final test is to try the default IMA measurement and appraisal
+policies, so that there is no gap between when the system starts and when
+the integrity evaluation is effective. The default policies actually will
+be used only until systemd is able to load the custom policy to
+measure/appraise binaries and shared libraries. It should be good enough
+for the system to boot.
+
+The default IMA measurement and appraisal policies can be loaded at boot by
+adding the following to the kernel command line:
+
+.. code-block:: bash
+
+ ima_policy="tcb|appraise_tcb|digest_cache_measure|digest_cache_appraise"
+
+The ima-modsig template can be selected by adding to the kernel command
+line:
+
+.. code-block:: bash
+
+ ima_template=ima-modsig
diff --git a/Documentation/security/index.rst b/Documentation/security/index.rst
index 59f8fc106cb0..34933e13c509 100644
--- a/Documentation/security/index.rst
+++ b/Documentation/security/index.rst
@@ -19,3 +19,4 @@ Security Documentation
digsig
landlock
secrets/index
+ digest_cache
diff --git a/MAINTAINERS b/MAINTAINERS
index ee52cc664bc7..076b6e9da194 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -6159,6 +6159,7 @@ DIGEST_CACHE LSM
M: Roberto Sassu <[email protected]>
L: [email protected]
S: Maintained
+F: Documentation/security/digest_cache.rst
F: security/digest_cache/
F: tools/testing/selftests/digest_cache/
--
2.34.1
Hi--
On 2/9/24 06:09, Roberto Sassu wrote:
> diff --git a/security/digest_cache/Kconfig b/security/digest_cache/Kconfig
> new file mode 100644
> index 000000000000..0c47d5151f07
> --- /dev/null
> +++ b/security/digest_cache/Kconfig
> @@ -0,0 +1,17 @@
> +# SPDX-License-Identifier: GPL-2.0
> +config SECURITY_DIGEST_CACHE
> + bool "Digest_cache LSM"
> + default n
> + help
> + This option enables an LSM maintaining a cache of digests
> + (e.g. of file content or metadata).
> +
> + This LSM can support other kernel components in making access
> + control decisions.
> +
nit: -ESTYLE.
coding-style.rst says:
Lines under a ``config`` definition
are indented with one tab, while help text is indented an additional two
spaces.
> +config DIGEST_LIST_DEFAULT_PATH
> + string
> + default "/etc/digest_lists"
> + help
> + Default directory where digest_cache LSM expects to find digest
> + lists.
Same comment for patch 03/13.
Same comment for patch 04/13.
--
#Randy
On Fri, 2024-02-09 at 15:00 -0800, Randy Dunlap wrote:
> Hi--
>
> On 2/9/24 06:09, Roberto Sassu wrote:
> > diff --git a/security/digest_cache/Kconfig b/security/digest_cache/Kconfig
> > new file mode 100644
> > index 000000000000..0c47d5151f07
> > --- /dev/null
> > +++ b/security/digest_cache/Kconfig
> > @@ -0,0 +1,17 @@
> > +# SPDX-License-Identifier: GPL-2.0
> > +config SECURITY_DIGEST_CACHE
> > + bool "Digest_cache LSM"
> > + default n
> > + help
> > + This option enables an LSM maintaining a cache of digests
> > + (e.g. of file content or metadata).
> > +
> > + This LSM can support other kernel components in making access
> > + control decisions.
> > +
>
> nit: -ESTYLE.
> coding-style.rst says:
>
> Lines under a ``config`` definition
> are indented with one tab, while help text is indented an additional two
> spaces.
>
> > +config DIGEST_LIST_DEFAULT_PATH
> > + string
> > + default "/etc/digest_lists"
> > + help
> > + Default directory where digest_cache LSM expects to find digest
> > + lists.
>
> Same comment for patch 03/13.
> Same comment for patch 04/13.
Hi Randy
thanks, will apply your suggestions to the next version.
Roberto
On Fri, 2024-02-09 at 15:09 +0100, Roberto Sassu wrote:
> From: Roberto Sassu <[email protected]>
>
> Introduce the digest_cache LSM, whose purpose is to deliver reference
> digest values to integrity providers, such as IMA and IPE, abstracting to
> them how those digests where extracted from the respective data source.
>
> The major benefit is the ability to use the vaste amount of digests already
> provided (and likely signed) by software vendors, without needing them to
> adapt their format to the one understood by the integrity provider.
>
> IMA and IPE can immediately interface with the digest_cache LSM and query
> the digest of an accessed file. If the digest is found, it means that the
> file is coming from the software vendor and not modified. If not, the file
> might have been corrupted. Each integrity provider decides how to handle
> this situation.
>
> The second major benefit is performance improvement. Since the digest_cache
> LSM has the ability to extract many digests from a single data source, it
> means that it has less signatures to verify compared to the approach of
> verifying individual file signatures (IMA appraisal). Preliminary tests
> have shown a speedup of IMA appraisal of about 65% for sequential read, and
> 45% for parallel read.
>
> This patch set has as prerequisites the file_release LSM hook (to be
> introduced with the move of IMA/EVM to the LSM infrastructure), and
> support for PGP keys, which is still unclear how it should be done.
>
> The IMA integration patch set will be introduced separately. Also a PoC
> based on the current version of IPE can be provided.
Hi everyone
I still hope to receive some comments on this and on the IMA
integration patch set.
Meanwhile, I built openSUSE Tumbleweed packages with both those patch
sets (with few changes) and the PGP one (with the parser in kernel
space).
I also published the first preliminary version of digest-cache-tools
which contains the tools to manage the digest_cache LSM.
https://github.com/linux-integrity/digest-cache-tools
The README should give a pretty good idea on how to configure the
digest_cache LSM correctly, to do IMA measurement (with predictable
PCR) and IMA appraisal.
That basically requires to install only the kernel and the digest-
cache-tools packages (plus dracut, to enable IMA measurement/appraisal
from the initial ram disk).
Other than that, openSUSE Tumbleweed with these three packages (and no
other modifications, even in the build infrastructure) is basically
offering the integrity features that IMA supports.
Roberto
> v2:
> - Include the TLV parser in this patch set (from user asymmetric keys and
> signatures)
> - Move from IMA and make an independent LSM
> - Remove IMA-specific stuff from this patch set
> - Add per algorithm hash table
> - Expect all digest lists to be in the same directory and allow changing
> the default directory
> - Support digest lookup on directories, when there is no
> security.digest_list xattr
> - Add seq num to digest list file name, to impose ordering on directory
> iteration
> - Add a new data type DIGEST_LIST_ENTRY_DATA for the nested data in the
> tlv digest list format
> - Add the concept of verification data attached to digest caches
> - Add the reset mechanism to track changes on digest lists and directory
> containing the digest lists
> - Add kernel selftests
>
> v1:
> - Add documentation in Documentation/security/integrity-digest-cache.rst
> - Pass the mask of IMA actions to digest_cache_alloc()
> - Add a reference count to the digest cache
> - Remove the path parameter from digest_cache_get(), and rely on the
> reference count to avoid the digest cache disappearing while being used
> - Rename the dentry_to_check parameter of digest_cache_get() to dentry
> - Rename digest_cache_get() to digest_cache_new() and add
> digest_cache_get() to set the digest cache in the iint of the inode for
> which the digest cache was requested
> - Add dig_owner and dig_user to the iint, to distinguish from which inode
> the digest cache was created from, and which is using it; consequently it
> makes the digest cache usable to measure/appraise other digest caches
> (support not yet enabled)
> - Add dig_owner_mutex and dig_user_mutex to serialize accesses to dig_owner
> and dig_user until they are initialized
> - Enforce strong synchronization and make the contenders wait until
> dig_owner and dig_user are assigned to the iint the first time
> - Move checking IMA actions on the digest list earlier, and fail if no
> action were performed (digest cache not usable)
> - Remove digest_cache_put(), not needed anymore with the introduction of
> the reference count
> - Fail immediately in digest_cache_lookup() if the digest algorithm is
> not set in the digest cache
> - Use 64 bit mask for IMA actions on the digest list instead of 8 bit
> - Return NULL in the inline version of digest_cache_get()
> - Use list_add_tail() instead of list_add() in the iterator
> - Copy the digest list path to a separate buffer in digest_cache_iter_dir()
> - Use digest list parsers verified with Frama-C
> - Explicitly disable (for now) the possibility in the IMA policy to use the
> digest cache to measure/appraise other digest lists
> - Replace exit(<value>) with return <value> in manage_digest_lists.c
>
> Roberto Sassu (13):
> lib: Add TLV parser
> security: Introduce the digest_cache LSM
> digest_cache: Add securityfs interface
> digest_cache: Add hash tables and operations
> digest_cache: Populate the digest cache from a digest list
> digest_cache: Parse tlv digest lists
> digest_cache: Parse rpm digest lists
> digest_cache: Add management of verification data
> digest_cache: Add support for directories
> digest cache: Prefetch digest lists if requested
> digest_cache: Reset digest cache on file/directory change
> selftests/digest_cache: Add selftests for digest_cache LSM
> docs: Add documentation of the digest_cache LSM
>
> Documentation/security/digest_cache.rst | 900 ++++++++++++++++++
> Documentation/security/index.rst | 1 +
> MAINTAINERS | 16 +
> include/linux/digest_cache.h | 89 ++
> include/linux/kernel_read_file.h | 1 +
> include/linux/tlv_parser.h | 28 +
> include/uapi/linux/lsm.h | 1 +
> include/uapi/linux/tlv_digest_list.h | 72 ++
> include/uapi/linux/tlv_parser.h | 59 ++
> include/uapi/linux/xattr.h | 6 +
> lib/Kconfig | 3 +
> lib/Makefile | 3 +
> lib/tlv_parser.c | 214 +++++
> lib/tlv_parser.h | 17 +
> security/Kconfig | 11 +-
> security/Makefile | 1 +
> security/digest_cache/Kconfig | 34 +
> security/digest_cache/Makefile | 11 +
> security/digest_cache/dir.c | 245 +++++
> security/digest_cache/htable.c | 268 ++++++
> security/digest_cache/internal.h | 259 +++++
> security/digest_cache/main.c | 545 +++++++++++
> security/digest_cache/modsig.c | 66 ++
> security/digest_cache/parsers/parsers.h | 15 +
> security/digest_cache/parsers/rpm.c | 223 +++++
> security/digest_cache/parsers/tlv.c | 299 ++++++
> security/digest_cache/populate.c | 163 ++++
> security/digest_cache/reset.c | 168 ++++
> security/digest_cache/secfs.c | 87 ++
> security/digest_cache/verif.c | 119 +++
> security/security.c | 3 +-
> tools/testing/selftests/Makefile | 1 +
> .../testing/selftests/digest_cache/.gitignore | 3 +
> tools/testing/selftests/digest_cache/Makefile | 23 +
> .../testing/selftests/digest_cache/all_test.c | 706 ++++++++++++++
> tools/testing/selftests/digest_cache/common.c | 79 ++
> tools/testing/selftests/digest_cache/common.h | 131 +++
> .../selftests/digest_cache/common_user.c | 47 +
> .../selftests/digest_cache/common_user.h | 17 +
> tools/testing/selftests/digest_cache/config | 1 +
> .../selftests/digest_cache/generators.c | 248 +++++
> .../selftests/digest_cache/generators.h | 19 +
> .../selftests/digest_cache/testmod/Makefile | 16 +
> .../selftests/digest_cache/testmod/kern.c | 499 ++++++++++
> .../selftests/lsm/lsm_list_modules_test.c | 3 +
> 45 files changed, 5714 insertions(+), 6 deletions(-)
> create mode 100644 Documentation/security/digest_cache.rst
> create mode 100644 include/linux/digest_cache.h
> create mode 100644 include/linux/tlv_parser.h
> create mode 100644 include/uapi/linux/tlv_digest_list.h
> create mode 100644 include/uapi/linux/tlv_parser.h
> create mode 100644 lib/tlv_parser.c
> create mode 100644 lib/tlv_parser.h
> create mode 100644 security/digest_cache/Kconfig
> create mode 100644 security/digest_cache/Makefile
> create mode 100644 security/digest_cache/dir.c
> create mode 100644 security/digest_cache/htable.c
> create mode 100644 security/digest_cache/internal.h
> create mode 100644 security/digest_cache/main.c
> create mode 100644 security/digest_cache/modsig.c
> create mode 100644 security/digest_cache/parsers/parsers.h
> create mode 100644 security/digest_cache/parsers/rpm.c
> create mode 100644 security/digest_cache/parsers/tlv.c
> create mode 100644 security/digest_cache/populate.c
> create mode 100644 security/digest_cache/reset.c
> create mode 100644 security/digest_cache/secfs.c
> create mode 100644 security/digest_cache/verif.c
> create mode 100644 tools/testing/selftests/digest_cache/.gitignore
> create mode 100644 tools/testing/selftests/digest_cache/Makefile
> create mode 100644 tools/testing/selftests/digest_cache/all_test.c
> create mode 100644 tools/testing/selftests/digest_cache/common.c
> create mode 100644 tools/testing/selftests/digest_cache/common.h
> create mode 100644 tools/testing/selftests/digest_cache/common_user.c
> create mode 100644 tools/testing/selftests/digest_cache/common_user.h
> create mode 100644 tools/testing/selftests/digest_cache/config
> create mode 100644 tools/testing/selftests/digest_cache/generators.c
> create mode 100644 tools/testing/selftests/digest_cache/generators.h
> create mode 100644 tools/testing/selftests/digest_cache/testmod/Makefile
> create mode 100644 tools/testing/selftests/digest_cache/testmod/kern.c
>