linux-kernel - [PATCH v2] IMA: Add audit log for failure conditions

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Message-Id: <20200607221449.2837-1-nramas@linux.microsoft.com>
Date:   Sun,  7 Jun 2020 15:14:49 -0700
From:   Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
To:     zohar@...ux.ibm.com, paul@...l-moore.com
Cc:     linux-integrity@...r.kernel.org, linux-audit@...hat.com,
        linux-kernel@...r.kernel.org
Subject: [PATCH v2] IMA: Add audit log for failure conditions

The final log statement in process_buffer_measurement() for failure
condition is at debug level. This does not log the message unless
the system log level is raised which would significantly increase
the messages in the system log. Change this log message to an audit
message for better triaging failures in the function.

ima_alloc_key_entry() does not log a message for failure condition.
Add an audit message for failure condition in this function.

Signed-off-by: Lakshmi Ramasubramanian <nramas@...ux.microsoft.com>
---
 security/integrity/ima/ima_main.c       | 17 ++++++++++++-----
 security/integrity/ima/ima_queue_keys.c |  4 ++++
 2 files changed, 16 insertions(+), 5 deletions(-)

diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 800fb3bba418..1225198fceb1 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -739,6 +739,7 @@ void process_buffer_measurement(const void *buf, int size,
 				int pcr, const char *keyring)
 {
 	int ret = 0;
+	const char *audit_cause = "ENOMEM";
 	struct ima_template_entry *entry = NULL;
 	struct integrity_iint_cache iint = {};
 	struct ima_event_data event_data = {.iint = &iint,
@@ -793,21 +794,27 @@ void process_buffer_measurement(const void *buf, int size,
 	iint.ima_hash->length = hash_digest_size[ima_hash_algo];
 
 	ret = ima_calc_buffer_hash(buf, size, iint.ima_hash);
-	if (ret < 0)
+	if (ret < 0) {
+		audit_cause = "calc_buffer_hash";
 		goto out;
+	}
 
 	ret = ima_alloc_init_template(&event_data, &entry, template);
-	if (ret < 0)
+	if (ret < 0) {
+		audit_cause = "alloc_init_template";
 		goto out;
+	}
 
 	ret = ima_store_template(entry, violation, NULL, buf, pcr);
-
-	if (ret < 0)
+	if (ret < 0) {
+		audit_cause = "store_template";
 		ima_free_template_entry(entry);
+	}
 
 out:
 	if (ret < 0)
-		pr_devel("%s: failed, result: %d\n", __func__, ret);
+		integrity_audit_msg(AUDIT_INTEGRITY_PCR, NULL, eventname,
+				    __func__, audit_cause, ret, 0);
 
 	return;
 }
diff --git a/security/integrity/ima/ima_queue_keys.c b/security/integrity/ima/ima_queue_keys.c
index cb3e3f501593..fa606ce68f87 100644
--- a/security/integrity/ima/ima_queue_keys.c
+++ b/security/integrity/ima/ima_queue_keys.c
@@ -68,6 +68,7 @@ static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
 						 size_t payload_len)
 {
 	int rc = 0;
+	const char *audit_cause = "ENOMEM";
 	struct ima_key_entry *entry;
 
 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
@@ -88,6 +89,9 @@ static struct ima_key_entry *ima_alloc_key_entry(struct key *keyring,
 
 out:
 	if (rc) {
+		integrity_audit_msg(AUDIT_INTEGRITY_PCR, NULL,
+				    keyring->description, __func__,
+				    audit_cause, rc, 0);
 		ima_free_key_entry(entry);
 		entry = NULL;
 	}
-- 
2.27.0