linux/security/selinux/hooks.c
Stephen Smalley cf1e870707 selinux: avoid silent denials in permissive mode under RCU walk
commit 3a28cff3bd upstream.

commit 0dc1ba24f7 ("SELINUX: Make selinux cache VFS RCU walks safe")
results in no audit messages at all if in permissive mode because the
cache is updated during the rcu walk and thus no denial occurs on
the subsequent ref walk.  Fix this by not updating the cache when
performing a non-blocking permission check.  This only affects search
and symlink read checks during rcu walk.

Fixes: 0dc1ba24f7 ("SELINUX: Make selinux cache VFS RCU walks safe")
Reported-by: BMK <bmktuwien@gmail.com>
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
[bwh: Backported to 3.16:
 - Add flags parameter to avc_update_node(), done upstream in commit
   fa1aa143ac "selinux: extended permissions for ioctls"
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
2019-07-09 22:03:45 +01:00

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