kernel/linux.git/security/keys/key.c, branch v3.6.8

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

2012-05-24T00:42:39+00:00

Pull user namespace enhancements from Eric Biederman: "This is a course correction for the user namespace, so that we can reach an inexpensive, maintainable, and reasonably complete implementation. Highlights: - Config guards make it impossible to enable the user namespace and code that has not been converted to be user namespace safe. - Use of the new kuid_t type ensures the if you somehow get past the config guards the kernel will encounter type errors if you enable user namespaces and attempt to compile in code whose permission checks have not been updated to be user namespace safe. - All uids from child user namespaces are mapped into the initial user namespace before they are processed. Removing the need to add an additional check to see if the user namespace of the compared uids remains the same. - With the user namespaces compiled out the performance is as good or better than it is today. - For most operations absolutely nothing changes performance or operationally with the user namespace enabled. - The worst case performance I could come up with was timing 1 billion cache cold stat operations with the user namespace code enabled. This went from 156s to 164s on my laptop (or 156ns to 164ns per stat operation). - (uid_t)-1 and (gid_t)-1 are reserved as an internal error value. Most uid/gid setting system calls treat these value specially anyway so attempting to use -1 as a uid would likely cause entertaining failures in userspace. - If setuid is called with a uid that can not be mapped setuid fails. I have looked at sendmail, login, ssh and every other program I could think of that would call setuid and they all check for and handle the case where setuid fails. - If stat or a similar system call is called from a context in which we can not map a uid we lie and return overflowuid. The LFS experience suggests not lying and returning an error code might be better, but the historical precedent with uids is different and I can not think of anything that would break by lying about a uid we can't map. - Capabilities are localized to the current user namespace making it safe to give the initial user in a user namespace all capabilities. My git tree covers all of the modifications needed to convert the core kernel and enough changes to make a system bootable to runlevel 1." Fix up trivial conflicts due to nearby independent changes in fs/stat.c * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits) userns: Silence silly gcc warning. cred: use correct cred accessor with regards to rcu read lock userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq userns: Convert cgroup permission checks to use uid_eq userns: Convert tmpfs to use kuid and kgid where appropriate userns: Convert sysfs to use kgid/kuid where appropriate userns: Convert sysctl permission checks to use kuid and kgids. userns: Convert proc to use kuid/kgid where appropriate userns: Convert ext4 to user kuid/kgid where appropriate userns: Convert ext3 to use kuid/kgid where appropriate userns: Convert ext2 to use kuid/kgid where appropriate. userns: Convert devpts to use kuid/kgid where appropriate userns: Convert binary formats to use kuid/kgid where appropriate userns: Add negative depends on entries to avoid building code that is userns unsafe userns: signal remove unnecessary map_cred_ns userns: Teach inode_capable to understand inodes whose uids map to other namespaces. userns: Fail exec for suid and sgid binaries with ids outside our user namespace. userns: Convert stat to return values mapped from kuids and kgids userns: Convert user specfied uids and gids in chown into kuids and kgid userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs ...

KEYS: Add invalidation support

2012-05-11T09:56:56+00:00

Add support for invalidating a key - which renders it immediately invisible to further searches and causes the garbage collector to immediately wake up, remove it from keyrings and then destroy it when it's no longer referenced. It's better not to do this with keyctl_revoke() as that marks the key to start returning -EKEYREVOKED to searches when what is actually desired is to have the key refetched. To invalidate a key the caller must be granted SEARCH permission by the key. This may be too strict. It may be better to also permit invalidation if the caller has any of READ, WRITE or SETATTR permission. The primary use for this is to evict keys that are cached in special keyrings, such as the DNS resolver or an ID mapper. Signed-off-by: David Howells

KEYS: Announce key type (un)registration

2012-05-11T09:56:56+00:00

Announce the (un)registration of a key type in the core key code rather than in the callers. Signed-off-by: David Howells Acked-by: Mimi Zohar

userns: Use cred->user_ns instead of cred->user->user_ns

2012-04-07T23:55:51+00:00

Optimize performance and prepare for the removal of the user_ns reference from user_struct. Remove the slow long walk through cred->user->user_ns and instead go straight to cred->user_ns. Acked-by: Serge Hallyn Signed-off-by: Eric W. Biederman

Created a function for setting timeouts on keys

2012-03-01T21:50:31+00:00

The keyctl_set_timeout function isn't exported to other parts of the kernel, but I want to use it for the NFS idmapper. I already have the key, but I wanted a generic way to set the timeout. Signed-off-by: Bryan Schumaker Acked-by: David Howells Signed-off-by: Trond Myklebust

keys: add a "logon" key type

2012-01-18T04:39:40+00:00

For CIFS, we want to be able to store NTLM credentials (aka username and password) in the keyring. We do not, however want to allow users to fetch those keys back out of the keyring since that would be a security risk. Unfortunately, due to the nuances of key permission bits, it's not possible to do this. We need to grant search permissions so the kernel can find these keys, but that also implies permissions to read the payload. Resolve this by adding a new key_type. This key type is essentially the same as key_type_user, but does not define a .read op. This prevents the payload from ever being visible from userspace. This key type also vets the description to ensure that it's "qualified" by checking to ensure that it has a ':' in it that is preceded by other characters. Acked-by: David Howells Signed-off-by: Jeff Layton Signed-off-by: Steve French

KEYS: Give key types their own lockdep class for key->sem

2011-11-16T22:35:32+00:00

Give keys their own lockdep class to differentiate them from each other in case a key of one type has to refer to a key of another type. Signed-off-by: David Howells Acked-by: Mimi Zohar Signed-off-by: James Morris

KEYS: Correctly destroy key payloads when their keytype is removed

2011-08-22T23:57:37+00:00

unregister_key_type() has code to mark a key as dead and make it unavailable in one loop and then destroy all those unavailable key payloads in the next loop. However, the loop to mark keys dead renders the key undetectable to the second loop by changing the key type pointer also. Fix this by the following means: (1) The key code has two garbage collectors: one deletes unreferenced keys and the other alters keyrings to delete links to old dead, revoked and expired keys. They can end up holding each other up as both want to scan the key serial tree under spinlock. Combine these into a single routine. (2) Move the dead key marking, dead link removal and dead key removal into the garbage collector as a three phase process running over the three cycles of the normal garbage collection procedure. This is tracked by the KEY_GC_REAPING_DEAD_1, _2 and _3 state flags. unregister_key_type() then just unlinks the key type from the list, wakes up the garbage collector and waits for the third phase to complete. (3) Downgrade the key types sem in unregister_key_type() once it has deleted the key type from the list so that it doesn't block the keyctl() syscall. (4) Dead keys that cannot be simply removed in the third phase have their payloads destroyed with the key's semaphore write-locked to prevent interference by the keyctl() syscall. There should be no in-kernel users of dead keys of that type by the point of unregistration, though keyctl() may be holding a reference. (5) Only perform timer recalculation in the GC if the timer actually expired. If it didn't, we'll get another cycle when it goes off - and if the key that actually triggered it has been removed, it's not a problem. (6) Only garbage collect link if the timer expired or if we're doing dead key clean up phase 2. (7) As only key_garbage_collector() is permitted to use rb_erase() on the key serial tree, it doesn't need to revalidate its cursor after dropping the spinlock as the node the cursor points to must still exist in the tree. (8) Drop the spinlock in the GC if there is contention on it or if we need to reschedule. After dealing with that, get the spinlock again and resume scanning. This has been tested in the following ways: (1) Run the keyutils testsuite against it. (2) Using the AF_RXRPC and RxKAD modules to test keytype removal: Load the rxrpc_s key type: # insmod /tmp/af-rxrpc.ko # insmod /tmp/rxkad.ko Create a key (http://people.redhat.com/~dhowells/rxrpc/listen.c): # /tmp/listen & [1] 8173 Find the key: # grep rxrpc_s /proc/keys 091086e1 I--Q-- 1 perm 39390000 0 0 rxrpc_s 52:2 Link it to a session keyring, preferably one with a higher serial number: # keyctl link 0x20e36251 @s Kill the process (the key should remain as it's linked to another place): # fg /tmp/listen ^C Remove the key type: rmmod rxkad rmmod af-rxrpc This can be made a more effective test by altering the following part of the patch: if (unlikely(gc_state & KEY_GC_REAPING_DEAD_2)) { /* Make sure everyone revalidates their keys if we marked a * bunch as being dead and make sure all keyring ex-payloads * are destroyed. */ kdebug("dead sync"); synchronize_rcu(); To call synchronize_rcu() in GC phase 1 instead. That causes that the keyring's old payload content to hang around longer until it's RCU destroyed - which usually happens after GC phase 3 is complete. This allows the destroy_dead_key branch to be tested. Reported-by: Benjamin Coddington Signed-off-by: David Howells Signed-off-by: James Morris

KEYS: Make the key reaper non-reentrant

2011-08-22T23:57:36+00:00

Make the key reaper non-reentrant by sticking it on the appropriate system work queue when we queue it. This will allow it to have global state and drop locks. It should probably be non-reentrant already as it may spend a long time holding the key serial spinlock, and so multiple entrants can spend long periods of time just sitting there spinning, waiting to get the lock. Signed-off-by: David Howells Signed-off-by: James Morris

KEYS: Move the unreferenced key reaper to the keys garbage collector file

2011-08-22T23:57:36+00:00

Move the unreferenced key reaper function to the keys garbage collector file as that's a more appropriate place with the dead key link reaper. Signed-off-by: David Howells Signed-off-by: James Morris