Messages in this thread Patch in this message | | | From | Aleksa Sarai <> | Subject | [PATCH] sched: debug: use task_pid_vnr in /proc/$pid/sched | Date | Sun, 6 Aug 2017 02:52:26 +1000 |
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It appears as though the addition of the PID namespace did not update the output code for /proc/$pid/sched, which made it trivial to figure out whether a process was inside &init_pid_ns from userspace (making container detection trivial[1]). This lead to situations such as:
% unshare -pf head -n1 /proc/self/sched head (10047, #threads: 1)
Fix this by just using task_pid_vnr for the output of /proc/$pid/sched. All of the other uses of task_pid_nr in kernel/sched/debug.c are from a sysctl context and thus don't need to be namespaced.
[1]: https://github.com/jessfraz/amicontained
Cc: <stable@vger.kernel.org> Cc: Jess Frazelle <acidburn@google.com> Signed-off-by: Aleksa Sarai <asarai@suse.com> --- kernel/sched/debug.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/sched/debug.c b/kernel/sched/debug.c index 4fa66de52bd6..a06acbe33e16 100644 --- a/kernel/sched/debug.c +++ b/kernel/sched/debug.c @@ -876,7 +876,7 @@ void proc_sched_show_task(struct task_struct *p, struct seq_file *m) { unsigned long nr_switches; - SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, task_pid_nr(p), + SEQ_printf(m, "%s (%d, #threads: %d)\n", p->comm, task_pid_vnr(p), get_nr_threads(p)); SEQ_printf(m, "---------------------------------------------------------" -- 2.13.3
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