[PATCH] keys: Permit running process to instantiate keys

Make it possible for a running process (such as gssapid) to be able to
instantiate a key, as was requested by Trond Myklebust for NFS4.

The patch makes the following changes:

 (1) A new, optional key type method has been added. This permits a key type
     to intercept requests at the point /sbin/request-key is about to be
     spawned and do something else with them - passing them over the
     rpc_pipefs files or netlink sockets for instance.

     The uninstantiated key, the authorisation key and the intended operation
     name are passed to the method.

 (2) The callout_info is no longer passed as an argument to /sbin/request-key
     to prevent unauthorised viewing of this data using ps or by looking in
     /proc/pid/cmdline.

     This means that the old /sbin/request-key program will not work with the
     patched kernel as it will expect to see an extra argument that is no
     longer there.

     A revised keyutils package will be made available tomorrow.

 (3) The callout_info is now attached to the authorisation key. Reading this
     key will retrieve the information.

 (4) A new field has been added to the task_struct. This holds the
     authorisation key currently active for a thread. Searches now look here
     for the caller's set of keys rather than looking for an auth key in the
     lowest level of the session keyring.

     This permits a thread to be servicing multiple requests at once and to
     switch between them. Note that this is per-thread, not per-process, and
     so is usable in multithreaded programs.

     The setting of this field is inherited across fork and exec.

 (5) A new keyctl function (KEYCTL_ASSUME_AUTHORITY) has been added that
     permits a thread to assume the authority to deal with an uninstantiated
     key. Assumption is only permitted if the authorisation key associated
     with the uninstantiated key is somewhere in the thread's keyrings.

     This function can also clear the assumption.

 (6) A new magic key specifier has been added to refer to the currently
     assumed authorisation key (KEY_SPEC_REQKEY_AUTH_KEY).

 (7) Instantiation will only proceed if the appropriate authorisation key is
     assumed first. The assumed authorisation key is discarded if
     instantiation is successful.

 (8) key_validate() is moved from the file of request_key functions to the
     file of permissions functions.

 (9) The documentation is updated.

From: <Valdis.Kletnieks@vt.edu>

    Build fix.

Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Alexander Zangerl <az@bond.edu.au>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 0 insertions, 45 deletions

diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index 09d92d5..d65a180 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -481,51 +481,6 @@ key_ref_t __keyring_search_one(key_ref_t keyring_ref,
 
 /*****************************************************************************/
 /*
- * search for an instantiation authorisation key matching a target key
- * - the RCU read lock must be held by the caller
- * - a target_id of zero specifies any valid token
- */
-struct key *keyring_search_instkey(struct key *keyring,
-				   key_serial_t target_id)
-{
-	struct request_key_auth *rka;
-	struct keyring_list *klist;
-	struct key *instkey;
-	int loop;
-
-	klist = rcu_dereference(keyring->payload.subscriptions);
-	if (klist) {
-		for (loop = 0; loop < klist->nkeys; loop++) {
-			instkey = klist->keys[loop];
-
-			if (instkey->type != &key_type_request_key_auth)
-				continue;
-
-			rka = instkey->payload.data;
-			if (target_id && rka->target_key->serial != target_id)
-				continue;
-
-			/* the auth key is revoked during instantiation */
-			if (!test_bit(KEY_FLAG_REVOKED, &instkey->flags))
-				goto found;
-
-			instkey = ERR_PTR(-EKEYREVOKED);
-			goto error;
-		}
-	}
-
-	instkey = ERR_PTR(-EACCES);
-	goto error;
-
-found:
-	atomic_inc(&instkey->usage);
-error:
-	return instkey;
-
-} /* end keyring_search_instkey() */
-
-/*****************************************************************************/
-/*
  * find a keyring with the specified name
  * - all named keyrings are searched
  * - only find keyrings with search permission for the process