From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751989AbdHEQw4 (ORCPT ); Sat, 5 Aug 2017 12:52:56 -0400 Received: from smtp2.provo.novell.com ([137.65.250.81]:45095 "EHLO smtp2.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751340AbdHEQwy (ORCPT ); Sat, 5 Aug 2017 12:52:54 -0400 From: Aleksa Sarai To: Ingo Molnar , Peter Zijlstra Cc: Aleksa Sarai , linux-kernel@vger.kernel.org, Aleksa Sarai , stable@vger.kernel.org, Jess Frazelle Subject: [PATCH] sched: debug: use task_pid_vnr in /proc/$pid/sched Date: Sun, 6 Aug 2017 02:52:26 +1000 Message-Id: <20170805165226.31398-1-asarai@suse.com> X-Mailer: git-send-email 2.13.3 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It appears as though the addition of the PID namespace did not update the output code for /proc/$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: Cc: Jess Frazelle Signed-off-by: Aleksa Sarai --- 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