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-rw-r--r--security/keys/keyctl.c40
1 files changed, 38 insertions, 2 deletions
diff --git a/security/keys/keyctl.c b/security/keys/keyctl.c
index 31a0fd8189f1..0d7b1946ff94 100644
--- a/security/keys/keyctl.c
+++ b/security/keys/keyctl.c
@@ -1013,12 +1013,42 @@ error:
*/
long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
{
+ return keyctl_reject_key(id, timeout, ENOKEY, ringid);
+}
+
+/*
+ * Negatively instantiate the key with the given timeout (in seconds) and error
+ * code and link the key into the destination keyring if one is given.
+ *
+ * The caller must have the appropriate instantiation permit set for this to
+ * work (see keyctl_assume_authority). No other permissions are required.
+ *
+ * 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 the specified error code until the negative key expires.
+ *
+ * If successful, 0 will be returned.
+ */
+long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
+ key_serial_t ringid)
+{
const struct cred *cred = current_cred();
struct request_key_auth *rka;
struct key *instkey, *dest_keyring;
long ret;
- kenter("%d,%u,%d", id, timeout, ringid);
+ kenter("%d,%u,%u,%d", id, timeout, error, ringid);
+
+ /* must be a valid error code and mustn't be a kernel special */
+ if (error <= 0 ||
+ error >= MAX_ERRNO ||
+ error == ERESTARTSYS ||
+ error == ERESTARTNOINTR ||
+ error == ERESTARTNOHAND ||
+ error == ERESTART_RESTARTBLOCK)
+ return -EINVAL;
/* the appropriate instantiation authorisation key must have been
* assumed before calling this */
@@ -1038,7 +1068,7 @@ long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
goto error;
/* instantiate the key and link it into a keyring */
- ret = key_negate_and_link(rka->target_key, timeout,
+ ret = key_reject_and_link(rka->target_key, timeout, error,
dest_keyring, instkey);
key_put(dest_keyring);
@@ -1492,6 +1522,12 @@ SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
case KEYCTL_SESSION_TO_PARENT:
return keyctl_session_to_parent();
+ case KEYCTL_REJECT:
+ return keyctl_reject_key((key_serial_t) arg2,
+ (unsigned) arg3,
+ (unsigned) arg4,
+ (key_serial_t) arg5);
+
default:
return -EOPNOTSUPP;
}