KEYS: Add KEYCTL_RESTRICT_KEYRING

Keyrings recently gained restrict_link capabilities that allow
individual keys to be validated prior to linking.  This functionality
was only available using internal kernel APIs.

With the KEYCTL_RESTRICT_KEYRING command existing keyrings can be
configured to check the content of keys before they are linked, and
then allow or disallow linkage of that key to the keyring.

To restrict a keyring, call:

  keyctl(KEYCTL_RESTRICT_KEYRING, key_serial_t keyring, const char *type,
         const char *restriction)

where 'type' is the name of a registered key type and 'restriction' is a
string describing how key linkage is to be restricted. The restriction
option syntax is specific to each key type.

Signed-off-by: Mat Martineau <mathew.j.martineau@linux.intel.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/security/keys/internal.h b/security/keys/internal.h
index 24762ae9a198..6ce016314897 100644
--- a/security/keys/internal.h
+++ b/security/keys/internal.h
@@ -252,6 +252,9 @@ struct iov_iter;
 extern long keyctl_instantiate_key_common(key_serial_t,
 					  struct iov_iter *,
 					  key_serial_t);
+extern long keyctl_restrict_keyring(key_serial_t id,
+				    const char __user *_type,
+				    const char __user *_restriction);
 #ifdef CONFIG_PERSISTENT_KEYRINGS
 extern long keyctl_get_persistent(uid_t, key_serial_t);
 extern unsigned persistent_keyring_expiry;