[RFC][PATCH v2 01/13] ima: Introduce hook DIGEST_LIST_CHECK

From: Roberto Sassu
Date: Sat Aug 12 2023 - 06:48:05 EST


From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>

Introduce a new hook to check the integrity of digest lists, whose digests
are added to the digest cache.

Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
Documentation/ABI/testing/ima_policy | 1 +
include/linux/kernel_read_file.h | 1 +
security/integrity/ima/ima.h | 1 +
security/integrity/ima/ima_main.c | 3 ++-
security/integrity/ima/ima_policy.c | 3 +++
5 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy
index 49db0ff288e..14d92c687ef 100644
--- a/Documentation/ABI/testing/ima_policy
+++ b/Documentation/ABI/testing/ima_policy
@@ -36,6 +36,7 @@ Description:
[KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK]
[KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA]
[SETXATTR_CHECK][MMAP_CHECK_REQPROT]
+ [DIGEST_LIST_CHECK]
mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND]
[[^]MAY_EXEC]
fsmagic:= hex value
diff --git a/include/linux/kernel_read_file.h b/include/linux/kernel_read_file.h
index 90451e2e12b..85f602e49e2 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/integrity/ima/ima.h b/security/integrity/ima/ima.h
index c29db699c99..3aef3d8fb57 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -203,6 +203,7 @@ 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_check) \
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 365db0e43d7..81abdc8b233 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -771,7 +771,8 @@ 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 c9b3bd8f1bb..b32c83d8a72 100644
--- a/security/integrity/ima/ima_policy.c
+++ b/security/integrity/ima/ima_policy.c
@@ -1287,6 +1287,7 @@ 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 |
@@ -1530,6 +1531,8 @@ 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)
--
2.34.1