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| author | David Howells <dhowells@redhat.com> | 2009-04-09 17:14:05 +0100 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-09 10:41:19 -0700 |
| commit | 34574dd10b6d0697b86703388d6d6af9cbf4bb48 (patch) | |
| tree | 89eb52c0777687d4704d3ab3a370c50c1fe9479c /security/keys | |
| parent | 11ff5f6affe9b75f115a900a5584db339d46002b (diff) | |
| download | linux-34574dd10b6d0697b86703388d6d6af9cbf4bb48.tar.gz linux-34574dd10b6d0697b86703388d6d6af9cbf4bb48.tar.bz2 linux-34574dd10b6d0697b86703388d6d6af9cbf4bb48.zip | |
keys: Handle there being no fallback destination keyring for request_key()
When request_key() is called, without there being any standard process
keyrings on which to fall back if a destination keyring is not specified, an
oops is liable to occur when construct_alloc_key() calls down_write() on
dest_keyring's semaphore.
Due to function inlining this may be seen as an oops in down_write() as called
from request_key_and_link().
This situation crops up during boot, where request_key() is called from within
the kernel (such as in CIFS mounts) where nobody is actually logged in, and so
PAM has not had a chance to create a session keyring and user keyrings to act
as the fallback.
To fix this, make construct_alloc_key() not attempt to cache a key if there is
no fallback key if no destination keyring is given specifically.
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'security/keys')
| -rw-r--r-- | security/keys/request_key.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/security/keys/request_key.c b/security/keys/request_key.c index 22a31582bfaa..03fe63ed55bd 100644 --- a/security/keys/request_key.c +++ b/security/keys/request_key.c @@ -311,7 +311,8 @@ static int construct_alloc_key(struct key_type *type, set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags); - down_write(&dest_keyring->sem); + if (dest_keyring) + down_write(&dest_keyring->sem); /* attach the key to the destination keyring under lock, but we do need * to do another check just in case someone beat us to it whilst we @@ -322,10 +323,12 @@ static int construct_alloc_key(struct key_type *type, if (!IS_ERR(key_ref)) goto key_already_present; - __key_link(dest_keyring, key); + if (dest_keyring) + __key_link(dest_keyring, key); mutex_unlock(&key_construction_mutex); - up_write(&dest_keyring->sem); + if (dest_keyring) + up_write(&dest_keyring->sem); mutex_unlock(&user->cons_lock); *_key = key; kleave(" = 0 [%d]", key_serial(key)); |