From 920c25c1fd7050174386a33f12e9cde456fe62ad Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Wed, 13 Jul 2016 01:37:22 +0100 Subject: [PATCH] fanotify: Taint on use of FANOTIFY_ACCESS_PERMISSIONS Forwarded: not-needed Various free and proprietary AV products use this feature and users apparently want it. But punting access checks to userland seems like an easy way to deadlock the system, and there will be nothing we can do about that. So warn and taint the kernel if this feature is actually used. Gbp-Pq: Topic debian Gbp-Pq: Name fanotify-taint-on-use-of-fanotify_access_permissions.patch --- fs/notify/fanotify/fanotify_user.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c index a12391d06fe..9a3562b31bf 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -1580,6 +1580,14 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask, if (ignored) mask &= ~FANOTIFY_EVENT_FLAGS; +#ifdef CONFIG_FANOTIFY_ACCESS_PERMISSIONS + if (mask & FANOTIFY_PERM_EVENTS) { + pr_warn_once("%s (%d): Using fanotify permission checks may lead to deadlock; tainting kernel\n", + current->comm, current->pid); + add_taint(TAINT_AUX, LOCKDEP_STILL_OK); + } +#endif + f = fdget(fanotify_fd); if (unlikely(!f.file)) return -EBADF; -- 2.30.2