In order to verify the OS kernel on PowerNV systems, secure boot requires
X.509 certificates trusted by the platform. These are stored in secure
variables controlled by OPAL, called OPAL secure variables. In order to
enable users to manage the keys, the secure variables need to be exposed
to userspace.
OPAL provides the runtime services for the kernel to be able to access the
secure variables[1]. This patchset defines the kernel interface for the
OPAL APIs. These APIs are used by the hooks, which load these variables
to the keyring and expose them to the userspace for reading/writing.
The previous version[2] of the patchset added support only for the sysfs
interface. This patch adds two more patches that involves loading of
the firmware trusted keys to the kernel keyring. This patchset is
dependent on the base CONFIG PPC_SECURE_BOOT added by ima arch specific
patches for POWER[3]
Overall, this patchset adds the following support:
* expose secure variables to the kernel via OPAL Runtime API interface
* expose secure variables to the userspace via kernel sysfs interface
* load kernel verification and revocation keys to .platform and
.blacklist keyring respectively.
The secure variables can be read/written using simple linux utilities
cat/hexdump.
For example:
Path to the secure variables is:
/sys/firmware/secvar/vars
Each secure variable is listed as directory.
$ ls -l
total 0
drwxr-xr-x. 2 root root 0 Aug 20 21:20 db
drwxr-xr-x. 2 root root 0 Aug 20 21:20 KEK
drwxr-xr-x. 2 root root 0 Aug 20 21:20 PK
The attributes of each of the secure variables are(for example: PK):
[PK]$ ls -l
total 0
-r--r--r--. 1 root root 32000 Aug 21 08:28 data
-r--r--r--. 1 root root 65536 Aug 21 08:28 name
-r--r--r--. 1 root root 65536 Aug 21 08:28 size
--w-------. 1 root root 32000 Aug 21 08:28 update
The "data" is used to read the existing variable value using hexdump. The
data is stored in ESL format.
The "update" is used to write a new value using cat. The update is
to be submitted as AUTH file.
[1] Depends on skiboot OPAL API changes which removes metadata from
the API. The new version with the changes are going to be posted soon.
[2] https://lkml.org/lkml/2019/6/13/1644
[3] https://lkml.org/lkml/2019/8/19/402
Changelog:
v2:
* removes complete efi-sms from the sysfs implementation and is simplified
* includes Greg's and Oliver's feedbacks:
* adds sysfs documentation
* moves sysfs code to arch/powerpc
* other code related feedbacks.
* adds two new patches to load keys to .platform and .blacklist keyring.
These patches are added to this series as they are also dependent on
OPAL APIs.
Nayna Jain (4):
powerpc/powernv: Add OPAL API interface to access secure variable
powerpc: expose secure variables to userspace via sysfs
x86/efi: move common keyring handler functions to new file
powerpc: load firmware trusted keys into kernel keyring
Documentation/ABI/testing/sysfs-secvar | 27 +++
arch/powerpc/Kconfig | 9 +
arch/powerpc/include/asm/opal-api.h | 5 +-
arch/powerpc/include/asm/opal.h | 6 +
arch/powerpc/include/asm/secvar.h | 55 +++++
arch/powerpc/kernel/Makefile | 3 +-
arch/powerpc/kernel/secvar-ops.c | 25 +++
arch/powerpc/kernel/secvar-sysfs.c | 210 ++++++++++++++++++
arch/powerpc/platforms/powernv/Kconfig | 6 +
arch/powerpc/platforms/powernv/Makefile | 1 +
arch/powerpc/platforms/powernv/opal-call.c | 3 +
arch/powerpc/platforms/powernv/opal-secvar.c | 102 +++++++++
arch/powerpc/platforms/powernv/opal.c | 5 +
security/integrity/Kconfig | 9 +
security/integrity/Makefile | 6 +-
.../platform_certs/keyring_handler.c | 80 +++++++
.../platform_certs/keyring_handler.h | 35 +++
.../integrity/platform_certs/load_powerpc.c | 94 ++++++++
security/integrity/platform_certs/load_uefi.c | 67 +-----
19 files changed, 679 insertions(+), 69 deletions(-)
create mode 100644 Documentation/ABI/testing/sysfs-secvar
create mode 100644 arch/powerpc/include/asm/secvar.h
create mode 100644 arch/powerpc/kernel/secvar-ops.c
create mode 100644 arch/powerpc/kernel/secvar-sysfs.c
create mode 100644 arch/powerpc/platforms/powernv/opal-secvar.c
create mode 100644 security/integrity/platform_certs/keyring_handler.c
create mode 100644 security/integrity/platform_certs/keyring_handler.h
create mode 100644 security/integrity/platform_certs/load_powerpc.c
--
2.20.1
This patch moves the common code to keyring_handler.c
Signed-off-by: Nayna Jain <[email protected]>
---
security/integrity/Makefile | 3 +-
.../platform_certs/keyring_handler.c | 80 +++++++++++++++++++
.../platform_certs/keyring_handler.h | 35 ++++++++
security/integrity/platform_certs/load_uefi.c | 67 +---------------
4 files changed, 118 insertions(+), 67 deletions(-)
create mode 100644 security/integrity/platform_certs/keyring_handler.c
create mode 100644 security/integrity/platform_certs/keyring_handler.h
diff --git a/security/integrity/Makefile b/security/integrity/Makefile
index 19faace69644..525bf1d6e0db 100644
--- a/security/integrity/Makefile
+++ b/security/integrity/Makefile
@@ -11,7 +11,8 @@ integrity-$(CONFIG_INTEGRITY_SIGNATURE) += digsig.o
integrity-$(CONFIG_INTEGRITY_ASYMMETRIC_KEYS) += digsig_asymmetric.o
integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o
integrity-$(CONFIG_LOAD_UEFI_KEYS) += platform_certs/efi_parser.o \
- platform_certs/load_uefi.o
+ platform_certs/load_uefi.o \
+ platform_certs/keyring_handler.o
integrity-$(CONFIG_LOAD_IPL_KEYS) += platform_certs/load_ipl_s390.o
$(obj)/load_uefi.o: KBUILD_CFLAGS += -fshort-wchar
diff --git a/security/integrity/platform_certs/keyring_handler.c b/security/integrity/platform_certs/keyring_handler.c
new file mode 100644
index 000000000000..c5ba695c10e3
--- /dev/null
+++ b/security/integrity/platform_certs/keyring_handler.c
@@ -0,0 +1,80 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/err.h>
+#include <linux/efi.h>
+#include <linux/slab.h>
+#include <keys/asymmetric-type.h>
+#include <keys/system_keyring.h>
+#include "../integrity.h"
+
+static efi_guid_t efi_cert_x509_guid __initdata = EFI_CERT_X509_GUID;
+static efi_guid_t efi_cert_x509_sha256_guid __initdata =
+ EFI_CERT_X509_SHA256_GUID;
+static efi_guid_t efi_cert_sha256_guid __initdata = EFI_CERT_SHA256_GUID;
+
+/*
+ * Blacklist a hash.
+ */
+static __init void uefi_blacklist_hash(const char *source, const void *data,
+ size_t len, const char *type,
+ size_t type_len)
+{
+ char *hash, *p;
+
+ hash = kmalloc(type_len + len * 2 + 1, GFP_KERNEL);
+ if (!hash)
+ return;
+ p = memcpy(hash, type, type_len);
+ p += type_len;
+ bin2hex(p, data, len);
+ p += len * 2;
+ *p = 0;
+
+ mark_hash_blacklisted(hash);
+ kfree(hash);
+}
+
+/*
+ * Blacklist an X509 TBS hash.
+ */
+static __init void uefi_blacklist_x509_tbs(const char *source,
+ const void *data, size_t len)
+{
+ uefi_blacklist_hash(source, data, len, "tbs:", 4);
+}
+
+/*
+ * Blacklist the hash of an executable.
+ */
+static __init void uefi_blacklist_binary(const char *source,
+ const void *data, size_t len)
+{
+ uefi_blacklist_hash(source, data, len, "bin:", 4);
+}
+
+/*
+ * Return the appropriate handler for particular signature list types found in
+ * the UEFI db and MokListRT tables.
+ */
+__init efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type)
+{
+ if (efi_guidcmp(*sig_type, efi_cert_x509_guid) == 0)
+ return add_to_platform_keyring;
+ return 0;
+}
+
+/*
+ * Return the appropriate handler for particular signature list types found in
+ * the UEFI dbx and MokListXRT tables.
+ */
+__init efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type)
+{
+ if (efi_guidcmp(*sig_type, efi_cert_x509_sha256_guid) == 0)
+ return uefi_blacklist_x509_tbs;
+ if (efi_guidcmp(*sig_type, efi_cert_sha256_guid) == 0)
+ return uefi_blacklist_binary;
+ return 0;
+}
diff --git a/security/integrity/platform_certs/keyring_handler.h b/security/integrity/platform_certs/keyring_handler.h
new file mode 100644
index 000000000000..829a14b95218
--- /dev/null
+++ b/security/integrity/platform_certs/keyring_handler.h
@@ -0,0 +1,35 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain <[email protected]>
+ */
+#ifndef PLATFORM_CERTS_INTERNAL_H
+#define PLATFORM_CERTS_INTERNAL_H
+
+#include <linux/efi.h>
+
+void blacklist_hash(const char *source, const void *data,
+ size_t len, const char *type,
+ size_t type_len);
+
+/*
+ * Blacklist an X509 TBS hash.
+ */
+void blacklist_x509_tbs(const char *source, const void *data, size_t len);
+
+/*
+ * Blacklist the hash of an executable.
+ */
+void blacklist_binary(const char *source, const void *data, size_t len);
+
+/*
+ * Return the handler for particular signature list types found in the db.
+ */
+efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type);
+
+/*
+ * Return the handler for particular signature list types found in the dbx.
+ */
+efi_element_handler_t get_handler_for_dbx(const efi_guid_t *sig_type);
+
+#endif
diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
index 81b19c52832b..4369204a19cd 100644
--- a/security/integrity/platform_certs/load_uefi.c
+++ b/security/integrity/platform_certs/load_uefi.c
@@ -9,6 +9,7 @@
#include <keys/asymmetric-type.h>
#include <keys/system_keyring.h>
#include "../integrity.h"
+#include "keyring_handler.h"
static efi_guid_t efi_cert_x509_guid __initdata = EFI_CERT_X509_GUID;
static efi_guid_t efi_cert_x509_sha256_guid __initdata =
@@ -67,72 +68,6 @@ static __init void *get_cert_list(efi_char16_t *name, efi_guid_t *guid,
return db;
}
-/*
- * Blacklist a hash.
- */
-static __init void uefi_blacklist_hash(const char *source, const void *data,
- size_t len, const char *type,
- size_t type_len)
-{
- char *hash, *p;
-
- hash = kmalloc(type_len + len * 2 + 1, GFP_KERNEL);
- if (!hash)
- return;
- p = memcpy(hash, type, type_len);
- p += type_len;
- bin2hex(p, data, len);
- p += len * 2;
- *p = 0;
-
- mark_hash_blacklisted(hash);
- kfree(hash);
-}
-
-/*
- * Blacklist an X509 TBS hash.
- */
-static __init void uefi_blacklist_x509_tbs(const char *source,
- const void *data, size_t len)
-{
- uefi_blacklist_hash(source, data, len, "tbs:", 4);
-}
-
-/*
- * Blacklist the hash of an executable.
- */
-static __init void uefi_blacklist_binary(const char *source,
- const void *data, size_t len)
-{
- uefi_blacklist_hash(source, data, len, "bin:", 4);
-}
-
-/*
- * Return the appropriate handler for particular signature list types found in
- * the UEFI db and MokListRT tables.
- */
-static __init efi_element_handler_t get_handler_for_db(const efi_guid_t *
- sig_type)
-{
- if (efi_guidcmp(*sig_type, efi_cert_x509_guid) == 0)
- return add_to_platform_keyring;
- return 0;
-}
-
-/*
- * Return the appropriate handler for particular signature list types found in
- * the UEFI dbx and MokListXRT tables.
- */
-static __init efi_element_handler_t get_handler_for_dbx(const efi_guid_t *
- sig_type)
-{
- if (efi_guidcmp(*sig_type, efi_cert_x509_sha256_guid) == 0)
- return uefi_blacklist_x509_tbs;
- if (efi_guidcmp(*sig_type, efi_cert_sha256_guid) == 0)
- return uefi_blacklist_binary;
- return 0;
-}
-
/*
* Load the certs contained in the UEFI databases into the platform trusted
* keyring and the UEFI blacklisted X.509 cert SHA256 hashes into the blacklist
--
2.20.1
On Wed, Aug 21, 2019 at 11:08:22AM -0400, Nayna Jain wrote:
> This patch moves the common code to keyring_handler.c
That says _what_ you are doing, but not _why_ you are doing it. We have
no idea :(
The keys used to verify the Host OS kernel are managed by OPAL as secure
variables. This patch loads the verification keys into the .platform
keyring and revocation keys into .blacklist keyring. This enables
verification and loading of the kernels signed by the boot time keys which
are trusted by firmware.
Signed-off-by: Nayna Jain <[email protected]>
---
security/integrity/Kconfig | 9 ++
security/integrity/Makefile | 3 +
.../integrity/platform_certs/load_powerpc.c | 94 +++++++++++++++++++
3 files changed, 106 insertions(+)
create mode 100644 security/integrity/platform_certs/load_powerpc.c
diff --git a/security/integrity/Kconfig b/security/integrity/Kconfig
index 0bae6adb63a9..2b4109c157e2 100644
--- a/security/integrity/Kconfig
+++ b/security/integrity/Kconfig
@@ -72,6 +72,15 @@ config LOAD_IPL_KEYS
depends on S390
def_bool y
+config LOAD_PPC_KEYS
+ bool "Enable loading of platform and revocation keys for POWER"
+ depends on INTEGRITY_PLATFORM_KEYRING
+ depends on PPC_SECURE_BOOT
+ def_bool y
+ help
+ Enable loading of db keys to the .platform keyring and dbx keys to
+ the .blacklist keyring for powerpc based platforms.
+
config INTEGRITY_AUDIT
bool "Enables integrity auditing support "
depends on AUDIT
diff --git a/security/integrity/Makefile b/security/integrity/Makefile
index 525bf1d6e0db..9eeb6b053de3 100644
--- a/security/integrity/Makefile
+++ b/security/integrity/Makefile
@@ -14,6 +14,9 @@ integrity-$(CONFIG_LOAD_UEFI_KEYS) += platform_certs/efi_parser.o \
platform_certs/load_uefi.o \
platform_certs/keyring_handler.o
integrity-$(CONFIG_LOAD_IPL_KEYS) += platform_certs/load_ipl_s390.o
+integrity-$(CONFIG_LOAD_PPC_KEYS) += platform_certs/efi_parser.o \
+ platform_certs/load_powerpc.o \
+ platform_certs/keyring_handler.o
$(obj)/load_uefi.o: KBUILD_CFLAGS += -fshort-wchar
subdir-$(CONFIG_IMA) += ima
diff --git a/security/integrity/platform_certs/load_powerpc.c b/security/integrity/platform_certs/load_powerpc.c
new file mode 100644
index 000000000000..f4d869171062
--- /dev/null
+++ b/security/integrity/platform_certs/load_powerpc.c
@@ -0,0 +1,94 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 IBM Corporation
+ * Author: Nayna Jain <[email protected]>
+ *
+ * load_powernv.c
+ * - loads keys and certs stored and controlled
+ * by the firmware.
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/cred.h>
+#include <linux/err.h>
+#include <linux/slab.h>
+#include <asm/secboot.h>
+#include <asm/secvar.h>
+#include "keyring_handler.h"
+
+static struct secvar_operations *secvarops;
+
+/*
+ * Get a certificate list blob from the named EFI variable.
+ */
+static __init void *get_cert_list(u8 *key, unsigned long keylen,
+ unsigned long *size)
+{
+ int rc;
+ void *db;
+
+ rc = secvarops->get_variable(key, keylen, NULL, size);
+ if (rc) {
+ pr_err("Couldn't get size: %d\n", rc);
+ return NULL;
+ }
+
+ db = kmalloc(*size, GFP_KERNEL);
+ if (!db)
+ return NULL;
+
+ rc = secvarops->get_variable(key, keylen, db, size);
+ if (rc) {
+ kfree(db);
+ pr_err("Error reading db var: %d\n", rc);
+ return NULL;
+ }
+
+ return db;
+}
+
+/*
+ * Load the certs contained in the UEFI databases into the platform trusted
+ * keyring and the UEFI blacklisted X.509 cert SHA256 hashes into the blacklist
+ * keyring.
+ */
+static int __init load_powerpc_certs(void)
+{
+ void *db = NULL, *dbx = NULL;
+ unsigned long dbsize = 0, dbxsize = 0;
+ int rc = 0;
+
+ secvarops = get_secvar_ops();
+ if (!secvarops)
+ return -ENOENT;
+
+ /* Get db, and dbx. They might not exist, so it isn't
+ * an error if we can't get them.
+ */
+ db = get_cert_list("db", 3, &dbsize);
+ if (!db) {
+ pr_err("Couldn't get db list from OPAL\n");
+ } else {
+ rc = parse_efi_signature_list("OPAL:db",
+ db, dbsize, get_handler_for_db);
+ if (rc)
+ pr_err("Couldn't parse db signatures: %d\n",
+ rc);
+ kfree(db);
+ }
+
+ dbx = get_cert_list("dbx", 3, &dbxsize);
+ if (!dbx) {
+ pr_info("Couldn't get dbx list from OPAL\n");
+ } else {
+ rc = parse_efi_signature_list("OPAL:dbx",
+ dbx, dbxsize,
+ get_handler_for_dbx);
+ if (rc)
+ pr_err("Couldn't parse dbx signatures: %d\n", rc);
+ kfree(dbx);
+ }
+
+ return rc;
+}
+late_initcall(load_powerpc_certs);
--
2.20.1