[PATCH] implement in-kernel keys & keyring management

[David Howells <dhowells@redhat.com>]

Hi Linus, Andrew,

I've made available a patch that does a better job of key and keyring
management for authentication, cryptography, etc.. I've added a good bit of
documentation and I've commented the code more thoroughly.

The patch can be found at:

	http://people.redhat.com/~dhowells/keys/keys-268rc2.diff.bz2

	Signed-Off-By: David Howells <dhowells@redhat.com>

The documentation is patched into Documentation/keys.txt.


The feature set the patch includes:

 - Key attributes:
   - Key type
   - Description (by which a key of a particular type can be selected)
   - Payload
   - UID, GID and permissions mask
   - Expiry time
 - Keyrings (just a type of key that holds links to other keys)
 - User-defined keys
 - Key revokation
 - Access controls
 - Per user key-count and key-memory consumption quota
 - Three std keyrings per task: per-thread, per-process, session
 - Two std keyrings per user: per-user and default-user-session
 - prctl() functions for key and keyring creation and management
 - Kernel interfaces for filesystem, blockdev, net stack access
 - JIT key creation by usermode helper

There are also two utility programs available:

 (*) http://people.redhat.com/~dhowells/keys/keyctl.c

     A comprehensive key management tool, permitting all the interfaces
     available to userspace to be exercised.

 (*) http://people.redhat.com/~dhowells/keys/request-key

     An example shell script (to be installed in /sbin) for instantiating a
     key.

David