diff options
authorDavid Howells <dhowells@redhat.com>2014-03-09 08:21:58 +0000
committerLinus Torvalds <torvalds@linux-foundation.org>2014-03-09 18:57:18 -0700
commit979e0d74651ba5aa533277f2a6423d0f982fb6f6 (patch)
parent1dc3217dad3e771f2bd12703d6daed6cb818fdd8 (diff)
KEYS: Make the keyring cycle detector ignore other keyrings of the same name
This fixes CVE-2014-0102. The following command sequence produces an oops: keyctl new_session i=`keyctl newring _ses @s` keyctl link @s $i The problem is that search_nested_keyrings() sees two keyrings that have matching type and description, so keyring_compare_object() returns true. s_n_k() then passes the key to the iterator function - keyring_detect_cycle_iterator() - which *should* check to see whether this is the keyring of interest, not just one with the same name. Because assoc_array_find() will return one and only one match, I assumed that the iterator function would only see an exact match or never be called - but the iterator isn't only called from assoc_array_find()... The oops looks something like this: kernel BUG at /data/fs/linux-2.6-fscache/security/keys/keyring.c:1003! invalid opcode: 0000 [#1] SMP ... RIP: keyring_detect_cycle_iterator+0xe/0x1f ... Call Trace: search_nested_keyrings+0x76/0x2aa __key_link_check_live_key+0x50/0x5f key_link+0x4e/0x85 keyctl_keyring_link+0x60/0x81 SyS_keyctl+0x65/0xe4 tracesys+0xdd/0xe2 The fix is to make keyring_detect_cycle_iterator() check that the key it has is the key it was actually looking for rather than calling BUG_ON(). A testcase has been included in the keyutils testsuite for this: http://git.kernel.org/cgit/linux/kernel/git/dhowells/keyutils.git/commit/?id=891f3365d07f1996778ade0e3428f01878a1790b Reported-by: Tommi Rantala <tt.rantala@gmail.com> Signed-off-by: David Howells <dhowells@redhat.com> Acked-by: James Morris <james.l.morris@oracle.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1 files changed, 5 insertions, 1 deletions
diff --git a/security/keys/keyring.c b/security/keys/keyring.c
index d46cbc5e335e..2fb2576dc644 100644
--- a/security/keys/keyring.c
+++ b/security/keys/keyring.c
@@ -1000,7 +1000,11 @@ static int keyring_detect_cycle_iterator(const void *object,
kenter("{%d}", key->serial);
- BUG_ON(key != ctx->match_data);
+ /* We might get a keyring with matching index-key that is nonetheless a
+ * different keyring. */
+ if (key != ctx->match_data)
+ return 0;
ctx->result = ERR_PTR(-EDEADLK);
return 1;