sched/debug: Use task_pid_nr_ns in /proc/$pid/sched (74dc3384) · Commits · 戴 / test

It appears as though the addition of the PID namespace did not update the output code for /proc/*/sched, which resulted in it providing PIDs that were not self-consistent with the /proc mount. This additionally made it trivial to detect whether a process was inside &init_pid_ns from userspace, making container detection trivial: https://github.com/jessfraz/amicontained This leads to situations such as: % unshare -pmf % mount -t proc proc /proc % head -n1 /proc/1/sched head (10047, #threads: 1) Fix this by just using task_pid_nr_ns for the output of /proc/*/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. Signed-off-by:

Aleksa Sarai <asarai@suse.com> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by:

Eric W. Biederman <ebiederm@xmission.com> Cc: Jess Frazelle <acidburn@google.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: cyphar@cyphar.com Link: http://lkml.kernel.org/r/20170806044141.5093-1-asarai@suse.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

fs/proc/base.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -1408,12 +1408,13 @@ static const struct file_operations proc_fail_nth_operations = {
		static int sched_show(struct seq_file m, void v)
		{
		struct inode *inode = m->private;
		struct pid_namespace *ns = inode->i_sb->s_fs_info;
		struct task_struct *p;

		p = get_proc_task(inode);
		if (!p)
		return -ESRCH;
		proc_sched_show_task(p, m);
		proc_sched_show_task(p, ns, m);

		put_task_struct(p);

include/linux/sched/debug.h

+3 −1

Original line number	Diff line number	Diff line
		@@ -6,6 +6,7 @@
		*/

		struct task_struct;
		struct pid_namespace;

		extern void dump_cpu_task(int cpu);

		@@ -34,7 +35,8 @@ extern void sched_show_task(struct task_struct *p);

		#ifdef CONFIG_SCHED_DEBUG
		struct seq_file;
		extern void proc_sched_show_task(struct task_struct p, struct seq_file m);
		extern void proc_sched_show_task(struct task_struct *p,
		struct pid_namespace ns, struct seq_file m);
		extern void proc_sched_set_task(struct task_struct *p);
		#endif

kernel/sched/debug.c

+3 −2

Original line number	Diff line number	Diff line
		@@ -872,11 +872,12 @@ static void sched_show_numa(struct task_struct p, struct seq_file m)
		#endif
		}

		void proc_sched_show_task(struct task_struct p, struct seq_file m)
		void proc_sched_show_task(struct task_struct p, struct pid_namespace ns,
		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_nr_ns(p, ns),
		get_nr_threads(p));
		SEQ_printf(m,
		"---------------------------------------------------------"

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