linux/security
Yevgeny Pats 23567fd052 KEYS: Fix keyring ref leak in join_session_keyring()
This fixes CVE-2016-0728.

If a thread is asked to join as a session keyring the keyring that's already
set as its session, we leak a keyring reference.

This can be tested with the following program:

	#include <stddef.h>
	#include <stdio.h>
	#include <sys/types.h>
	#include <keyutils.h>

	int main(int argc, const char *argv[])
	{
		int i = 0;
		key_serial_t serial;

		serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING,
				"leaked-keyring");
		if (serial < 0) {
			perror("keyctl");
			return -1;
		}

		if (keyctl(KEYCTL_SETPERM, serial,
			   KEY_POS_ALL | KEY_USR_ALL) < 0) {
			perror("keyctl");
			return -1;
		}

		for (i = 0; i < 100; i++) {
			serial = keyctl(KEYCTL_JOIN_SESSION_KEYRING,
					"leaked-keyring");
			if (serial < 0) {
				perror("keyctl");
				return -1;
			}
		}

		return 0;
	}

If, after the program has run, there something like the following line in
/proc/keys:

3f3d898f I--Q---   100 perm 3f3f0000     0     0 keyring   leaked-keyring: empty

with a usage count of 100 * the number of times the program has been run,
then the kernel is malfunctioning.  If leaked-keyring has zero usages or
has been garbage collected, then the problem is fixed.

Reported-by: Yevgeny Pats <yevgeny@perception-point.io>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Don Zickus <dzickus@redhat.com>
Acked-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Jarod Wilson <jarod@redhat.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
2016-01-20 10:50:48 +11:00
..
apparmor apparmor: clarify CRYPTO dependency 2015-10-22 11:11:28 +11:00
integrity Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-01-17 19:13:15 -08:00
keys KEYS: Fix keyring ref leak in join_session_keyring() 2016-01-20 10:50:48 +11:00
selinux Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-01-17 19:13:15 -08:00
smack Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2016-01-17 19:13:15 -08:00
tomoyo convert a bunch of open-coded instances of memdup_user_nul() 2016-01-04 10:26:58 -05:00
yama Adding YAMA hooks also when YAMA is not stacked. 2015-08-04 01:36:18 +10:00
Kconfig Yama: remove needless CONFIG_SECURITY_YAMA_STACKED 2015-07-28 13:18:19 +10:00
Makefile LSM: Switch to lists of hooks 2015-05-12 15:00:41 +10:00
commoncap.c capabilities: add a securebit to disable PR_CAP_AMBIENT_RAISE 2015-09-04 16:54:41 -07:00
device_cgroup.c security/device_cgroup: Fix RCU_LOCKDEP_WARN() condition 2015-09-03 18:13:10 -07:00
inode.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2015-07-04 19:36:06 -07:00
lsm_audit.c Merge branch 'next' of git://git.infradead.org/users/pcmoore/selinux into next 2015-08-15 13:29:57 +10:00
min_addr.c
security.c security: Add hook to invalidate inode security labels 2015-12-24 11:09:40 -05:00