2021-09-15 16:34:56

by Roberto Sassu

[permalink] [raw]
Subject: [RFC][PATCH 1/9] ima: Introduce new hook DIGEST_LIST_CHECK

Introduce a new hook called DIGEST_LIST_CHECK to measure and appraise files
read by the kernel with type READING_DIGEST_LIST. Files with this type are:
- digest lists directly read by the kernel
- executables of digest list parsers
- files read by the parsers (including digest lists)

Typical rules with the new hook are:
- measure func=DIGEST_LIST_CHECK pcr=11
- appraise func=DIGEST_LIST_CHECK appraise_type=imasig|modsig

Signed-off-by: Roberto Sassu <[email protected]>
---
security/integrity/ima/ima.h | 1 +
security/integrity/ima/ima_main.c | 3 ++-
security/integrity/ima/ima_policy.c | 3 +++
3 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index be965a8715e4..d01ca3566aec 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -202,6 +202,7 @@ static inline unsigned int ima_hash_key(u8 *digest)
hook(KEY_CHECK, key) \
hook(CRITICAL_DATA, critical_data) \
hook(SETXATTR_CHECK, setxattr_check) \
+ hook(DIGEST_LIST_CHECK, digest_list) \
hook(MAX_CHECK, none)

#define __ima_hook_enumify(ENUM, str) ENUM,
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 26a709207ca3..d33765c7aaa7 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -723,7 +723,8 @@ const int read_idmap[READING_MAX_ID] = {
[READING_MODULE] = MODULE_CHECK,
[READING_KEXEC_IMAGE] = KEXEC_KERNEL_CHECK,
[READING_KEXEC_INITRAMFS] = KEXEC_INITRAMFS_CHECK,
- [READING_POLICY] = POLICY_CHECK
+ [READING_POLICY] = POLICY_CHECK,
+ [READING_DIGEST_LIST] = DIGEST_LIST_CHECK
};

/**
diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
index 761ae5b63735..8d6f5d85dfa4 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1222,6 +1222,7 @@ static bool ima_validate_rule(struct ima_rule_entry *entry)
case MODULE_CHECK:
case KEXEC_KERNEL_CHECK:
case KEXEC_INITRAMFS_CHECK:
+ case DIGEST_LIST_CHECK:
if (entry->flags & ~(IMA_FUNC | IMA_MASK | IMA_FSMAGIC |
IMA_UID | IMA_FOWNER | IMA_FSUUID |
IMA_INMASK | IMA_EUID | IMA_PCR |
@@ -1446,6 +1447,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry)
entry->func = CRITICAL_DATA;
else if (strcmp(args[0].from, "SETXATTR_CHECK") == 0)
entry->func = SETXATTR_CHECK;
+ else if (strcmp(args[0].from, "DIGEST_LIST_CHECK") == 0)
+ entry->func = DIGEST_LIST_CHECK;
else
result = -EINVAL;
if (!result)
--
2.25.1