linux-kernel - [RESEND] proc, coredump: add CoreDumping flag to /proc/pid/status

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20170920230634.31572-1-guro@fb.com>
Date:   Wed, 20 Sep 2017 16:06:34 -0700
From:   Roman Gushchin <guro@...com>
To:     Andrew Morton <akpm@...ux-foundation.org>
CC:     Linus Torvalds <torvalds@...ux-foundation.org>,
        <linux-mm@...ck.org>, Roman Gushchin <guro@...com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Ingo Molnar <mingo@...nel.org>, <kernel-team@...com>,
        <linux-kernel@...r.kernel.org>
Subject: [RESEND] proc, coredump: add CoreDumping flag to /proc/pid/status

Right now there is no convenient way to check if a process is being
coredumped at the moment.

It might be necessary to recognize such state to prevent killing
the process and getting a broken coredump.
Writing a large core might take significant time, and the process
is unresponsive during it, so it might be killed by timeout,
if another process is monitoring and killing/restarting
hanging tasks.

To provide an ability to detect if a process is in the state of
being coreduped, we can expose a boolean CoreDumping flag
in /proc/pid/status.

Example:
$ cat core.sh
  #!/bin/sh

  echo "|/usr/bin/sleep 10" > /proc/sys/kernel/core_pattern
  sleep 1000 &
  PID=$!

  cat /proc/$PID/status | grep CoreDumping
  kill -ABRT $PID
  sleep 1
  cat /proc/$PID/status | grep CoreDumping

$ ./core.sh
  CoreDumping:	0
  CoreDumping:	1

Signed-off-by: Roman Gushchin <guro@...com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Alexander Viro <viro@...iv.linux.org.uk>
Cc: Ingo Molnar <mingo@...nel.org>
Cc: kernel-team@...com
Cc: linux-kernel@...r.kernel.org
---
 fs/proc/array.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/fs/proc/array.c b/fs/proc/array.c
index 88c355574aa0..fc4a0aa7f487 100644
--- a/fs/proc/array.c
+++ b/fs/proc/array.c
@@ -369,6 +369,11 @@ static void task_cpus_allowed(struct seq_file *m, struct task_struct *task)
 		   cpumask_pr_args(&task->cpus_allowed));
 }
 
+static inline void task_core_dumping(struct seq_file *m, struct mm_struct *mm)
+{
+	seq_printf(m, "CoreDumping:\t%d\n", !!mm->core_state);
+}
+
 int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
 			struct pid *pid, struct task_struct *task)
 {
@@ -379,6 +384,7 @@ int proc_pid_status(struct seq_file *m, struct pid_namespace *ns,
 
 	if (mm) {
 		task_mem(m, mm);
+		task_core_dumping(m, mm);
 		mmput(mm);
 	}
 	task_sig(m, task);
-- 
2.13.5