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f36f8c75ae
linux/security/keys
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David Howells f36f8c75ae KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches 
Add support for per-user_namespace registers of persistent per-UID kerberos
caches held within the kernel.

This allows the kerberos cache to be retained beyond the life of all a user's
processes so that the user's cron jobs can work.

The kerberos cache is envisioned as a keyring/key tree looking something like:

	struct user_namespace
	  \___ .krb_cache keyring		- The register
		\___ _krb.0 keyring		- Root's Kerberos cache
		\___ _krb.5000 keyring		- User 5000's Kerberos cache
		\___ _krb.5001 keyring		- User 5001's Kerberos cache
			\___ tkt785 big_key	- A ccache blob
			\___ tkt12345 big_key	- Another ccache blob

Or possibly:

	struct user_namespace
	  \___ .krb_cache keyring		- The register
		\___ _krb.0 keyring		- Root's Kerberos cache
		\___ _krb.5000 keyring		- User 5000's Kerberos cache
		\___ _krb.5001 keyring		- User 5001's Kerberos cache
			\___ tkt785 keyring	- A ccache
				\___ krbtgt/REDHAT.COM@REDHAT.COM big_key
				\___ http/REDHAT.COM@REDHAT.COM user
				\___ afs/REDHAT.COM@REDHAT.COM user
				\___ nfs/REDHAT.COM@REDHAT.COM user
				\___ krbtgt/KERNEL.ORG@KERNEL.ORG big_key
				\___ http/KERNEL.ORG@KERNEL.ORG big_key

What goes into a particular Kerberos cache is entirely up to userspace.  Kernel
support is limited to giving you the Kerberos cache keyring that you want.

The user asks for their Kerberos cache by:

	krb_cache = keyctl_get_krbcache(uid, dest_keyring);

The uid is -1 or the user's own UID for the user's own cache or the uid of some
other user's cache (requires CAP_SETUID).  This permits rpc.gssd or whatever to
mess with the cache.

The cache returned is a keyring named "_krb.<uid>" that the possessor can read,
search, clear, invalidate, unlink from and add links to.  Active LSMs get a
chance to rule on whether the caller is permitted to make a link.

Each uid's cache keyring is created when it first accessed and is given a
timeout that is extended each time this function is called so that the keyring
goes away after a while.  The timeout is configurable by sysctl but defaults to
three days.

Each user_namespace struct gets a lazily-created keyring that serves as the
register.  The cache keyrings are added to it.  This means that standard key
search and garbage collection facilities are available.

The user_namespace struct's register goes away when it does and anything left
in it is then automatically gc'd.

Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Simo Sorce <simo@redhat.com>
cc: Serge E. Hallyn <serge.hallyn@ubuntu.com>
cc: Eric W. Biederman <ebiederm@xmission.com>
2013-09-24 10:35:19 +01:00
..
encrypted-keys KEYS: Add payload preparsing opportunity prior to key instantiate or update 2012-10-08 13:49:48 +10:30
big_key.c KEYS: Implement a big key type that can save to tmpfs 2013-09-24 10:35:18 +01:00
compat.c KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches 2013-09-24 10:35:19 +01:00
gc.c KEYS: Expand the capacity of a keyring 2013-09-24 10:35:18 +01:00
internal.h KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches 2013-09-24 10:35:19 +01:00
Kconfig KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches 2013-09-24 10:35:19 +01:00
key.c KEYS: Expand the capacity of a keyring 2013-09-24 10:35:18 +01:00
keyctl.c KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches 2013-09-24 10:35:19 +01:00
keyring.c KEYS: Expand the capacity of a keyring 2013-09-24 10:35:18 +01:00
Makefile KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches 2013-09-24 10:35:19 +01:00
permission.c userns: Convert security/keys to the new userns infrastructure 2012-09-13 18:28:02 -07:00
persistent.c KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches 2013-09-24 10:35:19 +01:00
proc.c KEYS: Introduce a search context structure 2013-09-24 10:35:15 +01:00
process_keys.c KEYS: Define a __key_get() wrapper to use rather than atomic_inc() 2013-09-24 10:35:16 +01:00
request_key_auth.c KEYS: Search for auth-key by name rather than target key ID 2013-09-24 10:35:16 +01:00
request_key.c KEYS: Expand the capacity of a keyring 2013-09-24 10:35:18 +01:00
sysctl.c KEYS: Add per-user_namespace registers for persistent per-UID kerberos caches 2013-09-24 10:35:19 +01:00
trusted.c Merge branch 'modules-next' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux 2012-10-14 13:39:34 -07:00
trusted.h trusted-keys: rename trusted_defined files to trusted 2011-01-24 10:14:22 +11:00
user_defined.c KEYS: Introduce a search context structure 2013-09-24 10:35:15 +01:00