KEYS: Allow keyctl_revoke() on keys that have SETATTR but not WRITE perm [try #6]

Allow keyctl_revoke() to operate on keys that have SETATTR but not WRITE
permission, rather than only on keys that have WRITE permission.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Signed-off-by: James Morris <jmorris@namei.org>

security/keys/keyctl.c

@@ -343,7 +343,13 @@ long keyctl_revoke_key(key_serial_t id)
 	key_ref = lookup_user_key(id, 0, KEY_WRITE);
 	if (IS_ERR(key_ref)) {
 		ret = PTR_ERR(key_ref);
+		if (ret != -EACCES)
 			goto error;
+		key_ref = lookup_user_key(id, 0, KEY_SETATTR);
+		if (IS_ERR(key_ref)) {
+			ret = PTR_ERR(key_ref);
+			goto error;
+		}
 	}
 
 	key_revoke(key_ref_to_ptr(key_ref));