The patch titled
Subject: proc: /proc/<pid>/timerslack_ns permissions fixes
has been added to the -mm tree. Its filename is
proc-add-proc-pid-timerslack_ns-interface-fix.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/proc-add-proc-pid-timerslack_ns-interface-fix.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/proc-add-proc-pid-timerslack_ns-interface-fix.patch
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------------------------------------------------------
From: John Stultz <john.stultz@xxxxxxxxxx>
Subject: proc: /proc/<pid>/timerslack_ns permissions fixes
This patch adjusts the timerslack_ns file permissions to be 0666 but
requires PTRACE_MODE_ATTACH_FSCREDS to read or write the value.
This allows tasks with sufficient privledges (CAP_SYS_PTRACE) to be able
to modify a the timerslack for proccesses owned by a different user.
This patch also fixes a return value from EINVAL to EPERM, and does task
locking consistently, given we're handling u64s on 32bit systems. It also
makes use of kstrtoull_from_user which simplifies some code.
I've also wired up the Android userspace side to use this interface, and
tested it there, and things seem to be working properly ( - with some
selinux noise, I still need to figure out the selinux policy changes, but
its working with permissive mode).
Signed-off-by: John Stultz <john.stultz@xxxxxxxxxx>
Cc: Arjan van de Ven <arjan@xxxxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Oren Laadan <orenl@xxxxxxxxxxx>
Cc: Ruchi Kandoi <kandoiruchi@xxxxxxxxxx>
Cc: Rom Lemarchand <romlem@xxxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Android Kernel Team <kernel-team@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/base.c | 28 +++++++++++++---------------
1 file changed, 13 insertions(+), 15 deletions(-)
diff -puN fs/proc/base.c~proc-add-proc-pid-timerslack_ns-interface-fix fs/proc/base.c
--- a/fs/proc/base.c~proc-add-proc-pid-timerslack_ns-interface-fix
+++ a/fs/proc/base.c
@@ -2262,18 +2262,10 @@ static ssize_t timerslack_ns_write(struc
{
struct inode *inode = file_inode(file);
struct task_struct *p;
- char buffer[PROC_NUMBUF];
u64 slack_ns;
int err;
- memset(buffer, 0, sizeof(buffer));
- if (count > sizeof(buffer) - 1)
- count = sizeof(buffer) - 1;
-
- if (copy_from_user(buffer, buf, count))
- return -EFAULT;
-
- err = kstrtoull(strstrip(buffer), 10, &slack_ns);
+ err = kstrtoull_from_user(buf, count, 10, &slack_ns);
if (err < 0)
return err;
@@ -2282,12 +2274,14 @@ static ssize_t timerslack_ns_write(struc
return -ESRCH;
if (ptrace_may_access(p, PTRACE_MODE_ATTACH_FSCREDS)) {
+ task_lock(p);
if (slack_ns == 0)
p->timer_slack_ns = p->default_timer_slack_ns;
else
p->timer_slack_ns = slack_ns;
+ task_unlock(p);
} else
- count = -EINVAL;
+ count = -EPERM;
put_task_struct(p);
@@ -2298,18 +2292,22 @@ static int timerslack_ns_show(struct seq
{
struct inode *inode = m->private;
struct task_struct *p;
+ int err = 0;
p = get_proc_task(inode);
if (!p)
return -ESRCH;
- task_lock(p);
- seq_printf(m, "%llu\n", p->timer_slack_ns);
- task_unlock(p);
+ if (ptrace_may_access(p, PTRACE_MODE_ATTACH_FSCREDS)) {
+ task_lock(p);
+ seq_printf(m, "%llu\n", p->timer_slack_ns);
+ task_unlock(p);
+ } else
+ err = -EPERM;
put_task_struct(p);
- return 0;
+ return err;
}
static int timerslack_ns_open(struct inode *inode, struct file *filp)
@@ -2899,7 +2897,7 @@ static const struct pid_entry tgid_base_
#ifdef CONFIG_CHECKPOINT_RESTORE
REG("timers", S_IRUGO, proc_timers_operations),
#endif
- REG("timerslack_ns", S_IRUGO|S_IWUSR, proc_pid_set_timerslack_ns_operations),
+ REG("timerslack_ns", S_IRUGO|S_IWUGO, proc_pid_set_timerslack_ns_operations),
};
static int proc_tgid_base_readdir(struct file *file, struct dir_context *ctx)
_
Patches currently in -mm which might be from john.stultz@xxxxxxxxxx are
timer-convert-timer_slack_ns-from-unsigned-long-to-u64.patch
proc-add-proc-pid-timerslack_ns-interface.patch
proc-add-proc-pid-timerslack_ns-interface-fix.patch
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