[merged] proc-fix-timerslack_ns-cap_sys_nice-check-when-adjusting-self.patch removed from -mm tree

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The patch titled
     Subject: proc: fix timerslack_ns CAP_SYS_NICE check when adjusting self
has been removed from the -mm tree.  Its filename was
     proc-fix-timerslack_ns-cap_sys_nice-check-when-adjusting-self.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: John Stultz <john.stultz@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Acked-by: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: "Serge E. Hallyn" <serge@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Cc: Oren Laadan <orenl@xxxxxxxxxxx>
Cc: Ruchi Kandoi <kandoiruchi@xxxxxxxxxx>
Cc: Rom Lemarchand <romlem@xxxxxxxxxxx>
Cc: Todd Kjos <tkjos@xxxxxxxxxx>
Cc: Colin Cross <ccross@xxxxxxxxxxx>
Cc: Nick Kralevich <nnk@xxxxxxxxxx>
Cc: Dmitry Shmidt <dimitrysh@xxxxxxxxxx>
Cc: Elliott Hughes <enh@xxxxxxxxxx>
Cc: Android Kernel Team <kernel-team@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 fs/proc/base.c |   36 ++++++++++++++++++++----------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff -puN fs/proc/base.c~proc-fix-timerslack_ns-cap_sys_nice-check-when-adjusting-self fs/proc/base.c
--- a/fs/proc/base.c~proc-fix-timerslack_ns-cap_sys_nice-check-when-adjusting-self
+++ a/fs/proc/base.c
@@ -2280,15 +2280,17 @@ static ssize_t timerslack_ns_write(struc
 	if (!p)
 		return -ESRCH;
 
-	if (!capable(CAP_SYS_NICE)) {
-		count = -EPERM;
-		goto out;
-	}
-
-	err = security_task_setscheduler(p);
-	if (err) {
-		count = err;
-		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;
+		}
 	}
 
 	task_lock(p);
@@ -2314,14 +2316,16 @@ static int timerslack_ns_show(struct seq
 	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);
_

Patches currently in -mm which might be from john.stultz@xxxxxxxxxx are


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