Commit-ID: 2895a5e5b3ae78d9923a91fce405d4a2f32c4309 Gitweb: http://git.kernel.org/tip/2895a5e5b3ae78d9923a91fce405d4a2f32c4309 Author: Eric Caruso <[email protected]> AuthorDate: Wed, 8 Jun 2016 16:08:59 -0700 Committer: Thomas Gleixner <[email protected]> CommitDate: Thu, 9 Jun 2016 23:42:38 +0200
timerfd: Reject ALARM timerfds without CAP_WAKE_ALARM timerfd gives processes a way to set wake alarms, but unlike timers made using timer_create, timerfds don't check whether the process has CAP_WAKE_ALARM before setting alarm-time timers. CAP_WAKE_ALARM is supposed to gate this behavior and so it makes sense that we should deny permission to create such timerfds if the process doesn't have this capability. Signed-off-by: Eric Caruso <[email protected]> Cc: Todd Poynor <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Thomas Gleixner <[email protected]> --- fs/timerfd.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/fs/timerfd.c b/fs/timerfd.c index 053818d..9ae4abb 100644 --- a/fs/timerfd.c +++ b/fs/timerfd.c @@ -390,6 +390,11 @@ SYSCALL_DEFINE2(timerfd_create, int, clockid, int, flags) clockid != CLOCK_BOOTTIME_ALARM)) return -EINVAL; + if (!capable(CAP_WAKE_ALARM) && + (clockid == CLOCK_REALTIME_ALARM || + clockid == CLOCK_BOOTTIME_ALARM)) + return -EPERM; + ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); if (!ctx) return -ENOMEM; @@ -433,6 +438,11 @@ static int do_timerfd_settime(int ufd, int flags, return ret; ctx = f.file->private_data; + if (!capable(CAP_WAKE_ALARM) && isalarm(ctx)) { + fdput(f); + return -EPERM; + } + timerfd_setup_cancel(ctx, flags); /*
