diff options
author | David Howells <dhowells@redhat.com> | 2009-04-09 12:14:05 -0400 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-04-09 13:41:19 -0400 |
commit | 34574dd10b6d0697b86703388d6d6af9cbf4bb48 (patch) | |
tree | 89eb52c0777687d4704d3ab3a370c50c1fe9479c | |
parent | 11ff5f6affe9b75f115a900a5584db339d46002b (diff) |
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>
-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, | |||
311 | 311 | ||
312 | set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags); | 312 | set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags); |
313 | 313 | ||
314 | down_write(&dest_keyring->sem); | 314 | if (dest_keyring) |
315 | down_write(&dest_keyring->sem); | ||
315 | 316 | ||
316 | /* attach the key to the destination keyring under lock, but we do need | 317 | /* attach the key to the destination keyring under lock, but we do need |
317 | * to do another check just in case someone beat us to it whilst we | 318 | * 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, | |||
322 | if (!IS_ERR(key_ref)) | 323 | if (!IS_ERR(key_ref)) |
323 | goto key_already_present; | 324 | goto key_already_present; |
324 | 325 | ||
325 | __key_link(dest_keyring, key); | 326 | if (dest_keyring) |
327 | __key_link(dest_keyring, key); | ||
326 | 328 | ||
327 | mutex_unlock(&key_construction_mutex); | 329 | mutex_unlock(&key_construction_mutex); |
328 | up_write(&dest_keyring->sem); | 330 | if (dest_keyring) |
331 | up_write(&dest_keyring->sem); | ||
329 | mutex_unlock(&user->cons_lock); | 332 | mutex_unlock(&user->cons_lock); |
330 | *_key = key; | 333 | *_key = key; |
331 | kleave(" = 0 [%d]", key_serial(key)); | 334 | kleave(" = 0 [%d]", key_serial(key)); |