* [PATCH] fs/timerfd: reject ALARM timerfds without CAP_WAKE_ALARM
@ 2016-06-08 23:08 Eric Caruso
2016-06-09 21:48 ` [tip:timers/core] timerfd: Reject " tip-bot for Eric Caruso
0 siblings, 1 reply; 2+ messages in thread
From: Eric Caruso @ 2016-06-08 23:08 UTC (permalink / raw)
To: Thomas Gleixner; +Cc: Todd Poynor, linux-kernel, Eric Caruso
From: Eric Caruso <ejcaruso@google.com>
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 <ejcaruso@google.com>
---
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);
/*
--
2.8.0.rc3.226.g39d4020
^ permalink raw reply related [flat|nested] 2+ messages in thread
* [tip:timers/core] timerfd: Reject ALARM timerfds without CAP_WAKE_ALARM
2016-06-08 23:08 [PATCH] fs/timerfd: reject ALARM timerfds without CAP_WAKE_ALARM Eric Caruso
@ 2016-06-09 21:48 ` tip-bot for Eric Caruso
0 siblings, 0 replies; 2+ messages in thread
From: tip-bot for Eric Caruso @ 2016-06-09 21:48 UTC (permalink / raw)
To: linux-tip-commits; +Cc: tglx, toddpoynor, ejcaruso, mingo, hpa, linux-kernel
Commit-ID: 2895a5e5b3ae78d9923a91fce405d4a2f32c4309
Gitweb: http://git.kernel.org/tip/2895a5e5b3ae78d9923a91fce405d4a2f32c4309
Author: Eric Caruso <ejcaruso@google.com>
AuthorDate: Wed, 8 Jun 2016 16:08:59 -0700
Committer: Thomas Gleixner <tglx@linutronix.de>
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 <ejcaruso@google.com>
Cc: Todd Poynor <toddpoynor@google.com>
Link: http://lkml.kernel.org/r/1465427339-96209-1-git-send-email-ejcaruso@chromium.org
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
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);
/*
^ permalink raw reply related [flat|nested] 2+ messages in thread
end of thread, other threads:[~2016-06-09 21:49 UTC | newest]
Thread overview: 2+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-06-08 23:08 [PATCH] fs/timerfd: reject ALARM timerfds without CAP_WAKE_ALARM Eric Caruso
2016-06-09 21:48 ` [tip:timers/core] timerfd: Reject " tip-bot for Eric Caruso
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).