[PATCH v2 09/14] KEYS: Retry asym key search with partial ID in restrict_link_by_signature()

[Roberto Sassu]

From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>

Retry asymmetric key search in restrict_link_by_signature() to support the
case of partial IDs, provided by PGP signatures (only the last 8 bytes).

Although recently draft-ietf-openpgp-rfc4880bis-10 supports the signature
subpacket type 33, which contains the full issuer fingerprint, we cannot
rely on existing signatures to support it.

Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
---
 crypto/asymmetric_keys/restrict.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/crypto/asymmetric_keys/restrict.c b/crypto/asymmetric_keys/restrict.c
index afcd4d101ac5..dd3d4b3405f7 100644
--- a/crypto/asymmetric_keys/restrict.c
+++ b/crypto/asymmetric_keys/restrict.c
@@ -97,8 +97,14 @@ int restrict_link_by_signature(struct key *dest_keyring,
 	key = find_asymmetric_key(trust_keyring,
 				  sig->auth_ids[0], sig->auth_ids[1],
 				  sig->auth_ids[2], false);
-	if (IS_ERR(key))
-		return -ENOKEY;
+	if (IS_ERR(key)) {
+		/* Retry with a partial ID. */
+		key = find_asymmetric_key(trust_keyring,
+					  sig->auth_ids[0], sig->auth_ids[1],
+					  sig->auth_ids[2], true);
+		if (IS_ERR(key))
+			return -ENOKEY;
+	}
 
 	if (use_builtin_keys && !test_bit(KEY_FLAG_BUILTIN, &key->flags))
 		ret = -ENOKEY;
-- 
2.34.1