From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Introduce ima_digest_cache_load_verified_usage() to retrieve the verified
usage from the digest cache returned from the lookup of the digest
calculated by IMA on a file being accessed.
Verified usage cannot be loaded from the digest cache returned by
digest_cache_get() since the latter might return a directory digest cache,
which does not contain any verification data (only set to digest cache
populated from a file).
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
security/integrity/ima/ima_digest_cache.c | 37 +++++++++++++++++++++++
security/integrity/ima/ima_digest_cache.h | 9 ++++++
2 files changed, 46 insertions(+)
diff --git a/security/integrity/ima/ima_digest_cache.c b/security/integrity/ima/ima_digest_cache.c
index baa3faae77d2..bb8a9a9aa933 100644
--- a/security/integrity/ima/ima_digest_cache.c
+++ b/security/integrity/ima/ima_digest_cache.c
@@ -82,3 +82,40 @@ void ima_digest_cache_store_verified_usage(struct file *file,
pr_debug("Cannot set verified usage for %s, ret: %d, ignoring\n",
file_dentry(file)->d_name.name, rc);
}
+
+/**
+ * ima_digest_cache_load_verified_usage - Load verified usage from digest cache
+ * @dentry: Dentry of the inode for which the digest cache will be used
+ * @iint: Inode integrity metadata
+ *
+ * Load digest cache verified usage from the digest cache returned by
+ * digest_cache_lookup(), containing the file digest calculated by IMA (if the
+ * digest is found).
+ *
+ * Return: Verified usage if digest is found in digest cache, zero otherwise.
+ */
+u64 ima_digest_cache_load_verified_usage(struct dentry *dentry,
+ struct ima_iint_cache *iint)
+{
+ void *verified_usage_ptr;
+ uintptr_t found_cache_ptr;
+ struct digest_cache *found_cache;
+
+ if (!iint->digest_cache)
+ return 0ULL;
+
+ /* Do lookup to identify digest cache verification data is read from. */
+ found_cache_ptr = digest_cache_lookup(dentry, iint->digest_cache,
+ iint->ima_hash->digest,
+ iint->ima_hash->algo);
+ if (!found_cache_ptr)
+ return 0ULL;
+
+ found_cache = (struct digest_cache *)found_cache_ptr;
+
+ verified_usage_ptr = digest_cache_verif_get(found_cache, "ima");
+ if (!verified_usage_ptr)
+ return 0ULL;
+
+ return *(u64 *)verified_usage_ptr;
+}
diff --git a/security/integrity/ima/ima_digest_cache.h b/security/integrity/ima/ima_digest_cache.h
index 1544dc798631..41a37630b1f7 100644
--- a/security/integrity/ima/ima_digest_cache.h
+++ b/security/integrity/ima/ima_digest_cache.h
@@ -14,6 +14,8 @@ bool ima_digest_cache_get_check(struct dentry *dentry,
struct ima_iint_cache *iint);
void ima_digest_cache_store_verified_usage(struct file *file,
struct ima_iint_cache *iint);
+u64 ima_digest_cache_load_verified_usage(struct dentry *dentry,
+ struct ima_iint_cache *iint);
#else
static inline bool ima_digest_cache_get_check(struct dentry *dentry,
struct ima_iint_cache *iint)
@@ -26,4 +28,11 @@ ima_digest_cache_store_verified_usage(struct file *file,
struct ima_iint_cache *iint)
{ }
+static inline u64
+ima_digest_cache_load_verified_usage(struct dentry *dentry,
+ struct ima_iint_cache *iint)
+{
+ return 0ULL;
+}
+
#endif /* CONFIG_INTEGRITY_DIGEST_CACHE */
--
2.34.1
