diff options
| author | John Stultz | 2016-10-07 17:02:33 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2016-10-07 18:46:30 -0700 |
| commit | 4b2bd5fec007a4fd3fc82474b9199af25013de4c (patch) | |
| tree | 6cd4e88c476f3b7940df7e09e01c0a5355c2c886 /fs | |
| parent | 904763e1fb5eebf8249ec41a2019e5e32246df2f (diff) | |
proc: fix timerslack_ns CAP_SYS_NICE check when adjusting self
In changing from checking ptrace_may_access(p, PTRACE_MODE_ATTACH_FSCREDS)
to capable(CAP_SYS_NICE), I missed that ptrace_my_access succeeds when p
== current, but the CAP_SYS_NICE doesn't.
Thus while the previous commit was intended to loosen the needed
privileges to modify a processes timerslack, it needlessly restricted a
task modifying its own timerslack via the proc/<tid>/timerslack_ns
(which is permitted also via the PR_SET_TIMERSLACK method).
This patch corrects this by checking if p == current before checking the
CAP_SYS_NICE value.
This patch applies on top of my two previous patches currently in -mm
Link: http://lkml.kernel.org/r/1471906870-28624-1-git-send-email-john.stultz@linaro.org
Signed-off-by: John Stultz <john.stultz@linaro.org>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Oren Laadan <orenl@cellrox.com>
Cc: Ruchi Kandoi <kandoiruchi@google.com>
Cc: Rom Lemarchand <romlem@android.com>
Cc: Todd Kjos <tkjos@google.com>
Cc: Colin Cross <ccross@android.com>
Cc: Nick Kralevich <nnk@google.com>
Cc: Dmitry Shmidt <dimitrysh@google.com>
Cc: Elliott Hughes <enh@google.com>
Cc: Android Kernel Team <kernel-team@android.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs')
| -rw-r--r-- | fs/proc/base.c | 34 |
1 files changed, 19 insertions, 15 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index ebccdc192830..dc7fe5f3a53c 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2280,15 +2280,17 @@ static ssize_t timerslack_ns_write(struct file *file, const char __user *buf, if (!p) return -ESRCH; - if (!capable(CAP_SYS_NICE)) { - count = -EPERM; - goto out; - } + if (p != current) { + if (!capable(CAP_SYS_NICE)) { + count = -EPERM; + goto out; + } - err = security_task_setscheduler(p); - if (err) { - count = err; - goto out; + err = security_task_setscheduler(p); + if (err) { + count = err; + goto out; + } } task_lock(p); @@ -2314,14 +2316,16 @@ static int timerslack_ns_show(struct seq_file *m, void *v) if (!p) return -ESRCH; - if (!capable(CAP_SYS_NICE)) { - err = -EPERM; - goto out; - } + if (p != current) { - err = security_task_getscheduler(p); - if (err) - goto out; + if (!capable(CAP_SYS_NICE)) { + err = -EPERM; + goto out; + } + err = security_task_getscheduler(p); + if (err) + goto out; + } task_lock(p); seq_printf(m, "%llu\n", p->timer_slack_ns); |