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Date: Wed, 1 Mar 2017 03:58:06 -0800 From: tip-bot for Stephen Smalley <tipbot@...or.com> To: linux-tip-commits@...r.kernel.org Cc: tglx@...utronix.de, sds@...ho.nsa.gov, mingo@...nel.org, hpa@...or.com, linux-kernel@...r.kernel.org Subject: [tip:timers/urgent] timerfd: Only check CAP_WAKE_ALARM when it is needed Commit-ID: 25b68a8f0ab13a98de02650208ec927796659898 Gitweb: http://git.kernel.org/tip/25b68a8f0ab13a98de02650208ec927796659898 Author: Stephen Smalley <sds@...ho.nsa.gov> AuthorDate: Fri, 17 Feb 2017 10:13:59 -0500 Committer: Thomas Gleixner <tglx@...utronix.de> CommitDate: Wed, 1 Mar 2017 12:53:44 +0100 timerfd: Only check CAP_WAKE_ALARM when it is needed timerfd_create() and do_timerfd_settime() evaluate capable(CAP_WAKE_ALARM) unconditionally although CAP_WAKE_ALARM is only required for CLOCK_REALTIME_ALARM and CLOCK_BOOTTIME_ALARM. This can cause extraneous audit messages when using a LSM such as SELinux, incorrectly causes PF_SUPERPRIV to be set even when no privilege was exercised, and is inefficient. Flip the order of the tests in both functions so that we only call capable() if the capability is truly required for the operation. Signed-off-by: Stephen Smalley <sds@...ho.nsa.gov> Cc: linux-security-module@...r.kernel.org Cc: selinux@...ho.nsa.gov Link: http://lkml.kernel.org/r/1487344439-22293-1-git-send-email-sds@tycho.nsa.gov Signed-off-by: Thomas Gleixner <tglx@...utronix.de> --- fs/timerfd.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/fs/timerfd.c b/fs/timerfd.c index 384fa75..c543cdb 100644 --- a/fs/timerfd.c +++ b/fs/timerfd.c @@ -400,9 +400,9 @@ 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)) + if ((clockid == CLOCK_REALTIME_ALARM || + clockid == CLOCK_BOOTTIME_ALARM) && + !capable(CAP_WAKE_ALARM)) return -EPERM; ctx = kzalloc(sizeof(*ctx), GFP_KERNEL); @@ -449,7 +449,7 @@ static int do_timerfd_settime(int ufd, int flags, return ret; ctx = f.file->private_data; - if (!capable(CAP_WAKE_ALARM) && isalarm(ctx)) { + if (isalarm(ctx) && !capable(CAP_WAKE_ALARM)) { fdput(f); return -EPERM; }
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