IMA: Add support to limit measuring keys

Limit measuring keys to those keys being loaded onto a given set of
keyrings only and when the user id (uid) matches if uid is specified
in the policy.

This patch defines a new IMA policy option namely "keyrings=" that
can be used to specify a set of keyrings. If this option is specified
in the policy for "measure func=KEY_CHECK" then only the keys
loaded onto a keyring given in the "keyrings=" option are measured.

If uid is specified in the policy then the key is measured only if
the current user id matches the one specified in the policy.

Added a new parameter namely "keyring" (name of the keyring) to
process_buffer_measurement(). The keyring name is passed to
ima_get_action() to determine the required action.
ima_match_rules() is updated to check keyring in the policy, if
specified, for KEY_CHECK function.

Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>

1 files changed, 7 insertions, 1 deletions

diff --git a/security/integrity/ima/ima_asymmetric_keys.c b/security/integrity/ima/ima_asymmetric_keys.c
index 994d89d58af9..fea2e7dd3b09 100644
--- a/security/integrity/ima/ima_asymmetric_keys.c
+++ b/security/integrity/ima/ima_asymmetric_keys.c
@@ -46,7 +46,13 @@ void ima_post_key_create_or_update(struct key *keyring, struct key *key,
 	 * parameter to process_buffer_measurement() and is set
 	 * in the "eventname" field in ima_event_data for
 	 * the key measurement IMA event.
+	 *
+	 * The name of the keyring is also passed in the "keyring"
+	 * parameter to process_buffer_measurement() to check
+	 * if the IMA policy is configured to measure a key linked
+	 * to the given keyring.
 	 */
 	process_buffer_measurement(payload, payload_len,
-				   keyring->description, KEY_CHECK, 0);
+				   keyring->description, KEY_CHECK, 0,
+				   keyring->description);
 }