From b9ea4592373024e2fe43f96380a882d0d57ab5b9 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 2ff6bd85ba8..33b6a51391e 100644 --- a/fs/notify/fanotify/fanotify_user.c +++ b/fs/notify/fanotify/fanotify_user.c @@ -1544,6 +1544,14 @@ 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