user/sven/linux.git/security/keys/internal.h, branch v3.4.4

keys: add a "logon" key type

2012-01-18T04:39:40Z

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: Correctly destroy key payloads when their keytype is removed

2011-08-22T23:57:37Z

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

2011-08-22T23:57:36Z

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

KEYS: Improve /proc/keys

2011-03-17T00:59:32Z

Improve /proc/keys by: (1) Don't attempt to summarise the payload of a negated key. It won't have one. To this end, a helper function - key_is_instantiated() has been added that allows the caller to find out whether the key is positively instantiated (as opposed to being uninstantiated or negatively instantiated). (2) Do show keys that are negative, expired or revoked rather than hiding them. This requires an override flag (no_state_check) to be passed to search_my_process_keyrings() and keyring_search_aux() to suppress this check. Without this, keys that are possessed by the caller, but only grant permissions to the caller if possessed are skipped as the possession check fails. Keys that are visible due to user, group or other checks are visible with or without this patch. Signed-off-by: David Howells Signed-off-by: James Morris

KEYS: Add an iovec version of KEYCTL_INSTANTIATE

2011-03-08T00:17:22Z

Add a keyctl op (KEYCTL_INSTANTIATE_IOV) that is like KEYCTL_INSTANTIATE, but takes an iovec array and concatenates the data in-kernel into one buffer. Since the KEYCTL_INSTANTIATE copies the data anyway, this isn't too much of a problem. Signed-off-by: David Howells Signed-off-by: James Morris

KEYS: Add a new keyctl op to reject a key with a specified error code

2011-03-08T00:17:18Z

Add a new keyctl op to reject a key with a specified error code. This works much the same as negating a key, and so keyctl_negate_key() is made a special case of keyctl_reject_key(). The difference is that keyctl_negate_key() selects ENOKEY as the error to be reported. Typically the key would be rejected with EKEYEXPIRED, EKEYREVOKED or EKEYREJECTED, but this is not mandatory. Signed-off-by: David Howells Signed-off-by: James Morris

KEYS: Fix __key_link_end() quota fixup on error

2011-01-25T22:58:20Z

Fix __key_link_end()'s attempt to fix up the quota if an error occurs. There are two erroneous cases: Firstly, we always decrease the quota if the preallocated replacement keyring needs cleaning up, irrespective of whether or not we should (we may have replaced a pointer rather than adding another pointer). Secondly, we never clean up the quota if we added a pointer without the keyring storage being extended (we allocate multiple pointers at a time, even if we're not going to use them all immediately). We handle this by setting the bottom bit of the preallocation pointer in __key_link_begin() to indicate that the quota needs fixing up, which is then passed to __key_link() (which clears the whole thing) and __key_link_end(). Signed-off-by: David Howells Signed-off-by: Linus Torvalds

KEYS: Fix up comments in key management code

2011-01-21T22:59:30Z

Fix up comments in the key management code. No functional changes. Signed-off-by: David Howells Signed-off-by: Linus Torvalds

Add a dummy printk function for the maintenance of unused printks

2010-08-12T16:51:35Z

Add a dummy printk function for the maintenance of unused printks through gcc format checking, and also so that side-effect checking is maintained too. Signed-off-by: David Howells Signed-off-by: Linus Torvalds

KEYS: Make /proc/keys check to see if a key is possessed before security check

2010-08-02T05:34:27Z

Make /proc/keys check to see if the calling process possesses each key before performing the security check. The possession check can be skipped if the key doesn't have the possessor-view permission bit set. This causes the keys a process possesses to show up in /proc/keys, even if they don't have matching user/group/other view permissions. Signed-off-by: David Howells Signed-off-by: James Morris