On Tue, Jan 30, 2018 at 5:46 PM, Greg KH gregkh@linuxfoundation.org wrote:
On Tue, Jan 30, 2018 at 11:00:04AM -0800, Mark Salyzyn wrote:
On 01/19/2018 09:41 AM, Stephen Smalley wrote:
If we can't safely dereference the sock in these hooks, then that seems to point back to the approach used in my original code, where in ancient history I had sock_has_perm() take the socket and use its inode i_security field instead of the sock. commit 253bfae6e0ad97554799affa0266052968a45808 switched them to use the sock instead.
Because of the nature of this problem (hard to duplicate, no clear path), I am understandably not comfortable reverting and submitting for testing in order to prove this point. It is disruptive because it changes several subroutine call signatures.
AFAIK this looks like a user request racing in without reference counting or RCU grace period in the callers (could be viewed as not an issue with security code). Effectively fixed in 4.9-stable, but broken in 4.4-stable.
hygiene, KISS and small, is all I do feel comfortable to submit to 4.4-stable without pulling in all the infrastructure improvements.
-- Mark
security/selinux/hooks.c | 2 ++ 1 file changed, 2 insertions(+)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 34427384605d..be68992a28cb 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -4066,6 +4066,8 @@ static int sock_has_perm(struct task_struct *task, struct sock *sk, u32 perms) struct lsm_network_audit net = {0,}; u32 tsid = task_sid(task);
- if (!sksec)
return -EFAULT;This looks sane to me as a simple 4.4-only fix. If the SELinux maintainer acks it, I can easily queue this up.
This revision addresses my concerns with Mark's previous patch.
Acked-by: Paul Moore paul@paul-moore.com