linux/security
David Howells 979e0d7465 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>
2014-03-09 18:57:18 -07:00
..
apparmor Merge branch 'for-linus2' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2013-11-21 19:46:00 -08:00
integrity Merge to v3.13-rc7 for prerequisite changes in the Xen code for TPM 2014-01-06 22:23:01 +11:00
keys KEYS: Make the keyring cycle detector ignore other keyrings of the same name 2014-03-09 18:57:18 -07:00
selinux Merge branch 'stable-3.14' of git://git.infradead.org/users/pcmoore/selinux into for-linus 2014-02-24 14:40:16 +11:00
smack Merge git://git.infradead.org/users/eparis/audit 2014-01-23 18:08:10 -08:00
tomoyo Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-05-01 17:51:54 -07:00
yama yama: Better permission check for ptraceme 2013-03-26 13:17:58 -07:00
Kconfig security: select correct default LSM_MMAP_MIN_ADDR on arm on arm64 2014-02-05 14:59:14 +00:00
Makefile security: remove erroneous comment about capabilities.o link ordering 2013-09-24 11:26:28 +10:00
capability.c Linux 3.12 2013-11-26 17:32:55 -05:00
commoncap.c capabilities: allow nice if we are privileged 2013-08-30 23:44:09 -07:00
device_cgroup.c cgroup: replace cftype->read_seq_string() with cftype->seq_show() 2013-12-05 12:28:04 -05:00
inode.c securityfs: fix object creation races 2012-01-10 10:20:35 -05:00
lsm_audit.c Merge git://git.infradead.org/users/eparis/audit 2013-11-21 19:18:14 -08:00
min_addr.c mmap_min_addr check CAP_SYS_RAWIO only for write 2010-04-23 08:56:31 +10:00
security.c Linux 3.12 2013-11-26 17:32:55 -05:00