IMA: create machine owner and blacklist keyrings

This option creates IMA MOK and blacklist keyrings.  IMA MOK is an
intermediate keyring that sits between .system and .ima keyrings,
effectively forming a simple CA hierarchy.  To successfully import a key
into .ima_mok it must be signed by a key which CA is in .system keyring.
On turn any key that needs to go in .ima keyring must be signed by CA in
either .system or .ima_mok keyrings. IMA MOK is empty at kernel boot.

IMA blacklist keyring contains all revoked IMA keys.  It is consulted
before any other keyring.  If the search is successful the requested
operation is rejected and error is returned to the caller.

Signed-off-by: Petko Manolov <petkan@mip-labs.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>

1 files changed, 14 insertions, 0 deletions

diff --git a/security/integrity/digsig_asymmetric.c b/security/integrity/digsig_asymmetric.c
index 4fec1816a2b3..5ade2a7517a6 100644
--- a/security/integrity/digsig_asymmetric.c
+++ b/security/integrity/digsig_asymmetric.c
@@ -17,6 +17,7 @@
 #include <linux/key-type.h>
 #include <crypto/public_key.h>
 #include <keys/asymmetric-type.h>
+#include <keys/system_keyring.h>
 
 #include "integrity.h"
 
@@ -32,9 +33,22 @@ static struct key *request_asymmetric_key(struct key *keyring, uint32_t keyid)
 
 	pr_debug("key search: \"%s\"\n", name);
 
+	key = get_ima_blacklist_keyring();
+	if (key) {
+		key_ref_t kref;
+
+		kref = keyring_search(make_key_ref(key, 1),
+				     &key_type_asymmetric, name);
+		if (!IS_ERR(kref)) {
+			pr_err("Key '%s' is in ima_blacklist_keyring\n", name);
+			return ERR_PTR(-EKEYREJECTED);
+		}
+	}
+
 	if (keyring) {
 		/* search in specific keyring */
 		key_ref_t kref;
+
 		kref = keyring_search(make_key_ref(keyring, 1),
 				      &key_type_asymmetric, name);
 		if (IS_ERR(kref))