KEYS: Add a new keyctl op to reject a key with a specified error code

Add a new keyctl op to reject a key with a specified error code.  This works
much the same as negating a key, and so keyctl_negate_key() is made a special
case of keyctl_reject_key().  The difference is that keyctl_negate_key()
selects ENOKEY as the error to be reported.

Typically the key would be rejected with EKEYEXPIRED, EKEYREVOKED or
EKEYREJECTED, but this is not mandatory.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

1 files changed, 11 insertions, 8 deletions

diff --git a/security/keys/key.c b/security/keys/key.c
index 8e315ef2e88e..f7f9d93f08d9 100644
--- a/security/keys/key.c
+++ b/security/keys/key.c
@@ -511,26 +511,29 @@ int key_instantiate_and_link(struct key *key,
 EXPORT_SYMBOL(key_instantiate_and_link);
 
 /**
- * key_negate_and_link - Negatively instantiate a key and link it into the keyring.
+ * key_reject_and_link - Negatively instantiate a key and link it into the keyring.
  * @key: The key to instantiate.
  * @timeout: The timeout on the negative key.
+ * @error: The error to return when the key is hit.
  * @keyring: Keyring to create a link in on success (or NULL).
  * @authkey: The authorisation token permitting instantiation.
  *
  * Negatively instantiate a key that's in the uninstantiated state and, if
- * successful, set its timeout and link it in to the destination keyring if one
- * is supplied.  The key and any links to the key will be automatically garbage
- * collected after the timeout expires.
+ * successful, set its timeout and stored error and link it in to the
+ * destination keyring if one is supplied.  The key and any links to the key
+ * will be automatically garbage collected after the timeout expires.
  *
  * Negative keys are used to rate limit repeated request_key() calls by causing
- * them to return -ENOKEY until the negative key expires.
+ * them to return the stored error code (typically ENOKEY) until the negative
+ * key expires.
  *
  * If successful, 0 is returned, the authorisation token is revoked and anyone
  * waiting for the key is woken up.  If the key was already instantiated,
  * -EBUSY will be returned.
  */
-int key_negate_and_link(struct key *key,
+int key_reject_and_link(struct key *key,
 			unsigned timeout,
+			unsigned error,
 			struct key *keyring,
 			struct key *authkey)
 {
@@ -556,6 +559,7 @@ int key_negate_and_link(struct key *key,
 		atomic_inc(&key->user->nikeys);
 		set_bit(KEY_FLAG_NEGATIVE, &key->flags);
 		set_bit(KEY_FLAG_INSTANTIATED, &key->flags);
+		key->type_data.reject_error = -error;
 		now = current_kernel_time();
 		key->expiry = now.tv_sec + timeout;
 		key_schedule_gc(key->expiry + key_gc_delay);
@@ -585,8 +589,7 @@ int key_negate_and_link(struct key *key,
 
 	return ret == 0 ? link_ret : ret;
 }
-
-EXPORT_SYMBOL(key_negate_and_link);
+EXPORT_SYMBOL(key_reject_and_link);
 
 /*
  * Garbage collect keys in process context so that we don't have to disable