From: Christian Brauner <christian@brauner.io>
To: ebiederm@xmission.com, linux-kernel@vger.kernel.org
Cc: serge@hallyn.com, jannh@google.com, luto@kernel.org,
akpm@linux-foundation.org, oleg@redhat.com, cyphar@cyphar.com,
viro@zeniv.linux.org.uk, linux-fsdevel@vger.kernel.org,
linux-api@vger.kernel.org, dancol@google.com,
timmurray@google.com, linux-man@vger.kernel.org,
Christian Brauner <christian@brauner.io>
Subject: [PATCH v1 0/2] proc: allow signaling processes via file descriptors
Date: Mon, 19 Nov 2018 11:32:37 +0100 [thread overview]
Message-ID: <20181119103241.5229-1-christian@brauner.io> (raw)
Hey,
This little series introduces the ability to signal processes via file
descriptors to eliminate race-conditions caused by pid recycling.
With this patch an open() call on /proc/<pid> will give userspace a
handle to struct pid of the process associated with /proc/<pid>. This
allows to maintain a stable handle on a process.
Discussion has shown that a dedicated syscall is prefered over an ioctl().
Thus, the new syscall procfd_signal() is introduced to solve this
problem. It operates on a process file descriptor. More details are
found in the individual commit messages.
With this series a process can be killed via:
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <unistd.h>
int main(int argc, char *argv[])
{
int ret;
char buf[1000];
if (argc < 2)
exit(EXIT_FAILURE);
ret = snprintf(buf, sizeof(buf), "/proc/%s", argv[1]);
if (ret < 0)
exit(EXIT_FAILURE);
int fd = open(buf, O_DIRECTORY | O_CLOEXEC);
if (fd < 0) {
printf("%s - Failed to open \"%s\"\n", strerror(errno), buf);
exit(EXIT_FAILURE);
}
ret = syscall(__NR_procfd_signal, fd, SIGKILL, NULL, 0);
if (ret < 0) {
printf("Failed to send SIGKILL \"%s\"\n", strerror(errno));
close(fd);
exit(EXIT_FAILURE);
}
close(fd);
exit(EXIT_SUCCESS);
}
Thanks!
Christian
Christian Brauner (2):
proc: get process file descriptor from /proc/<pid>
signal: add procfd_signal() syscall
procfd_signal.2: document procfd_signal syscall
arch/x86/entry/syscalls/syscall_32.tbl | 1 +
arch/x86/entry/syscalls/syscall_64.tbl | 1 +
fs/proc/base.c | 23 ++++++++
include/linux/proc_fs.h | 1 +
include/linux/syscalls.h | 2 +
kernel/signal.c | 76 ++++++++++++++++++++++++--
6 files changed, 98 insertions(+), 6 deletions(-)
--
2.19.1
next reply other threads:[~2018-11-19 10:33 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-19 10:32 Christian Brauner [this message]
2018-11-19 10:32 ` [PATCH v1 1/2] proc: get process file descriptor from /proc/<pid> Christian Brauner
2018-11-19 15:32 ` Andy Lutomirski
2018-11-19 18:20 ` Christian Brauner
2018-11-19 10:32 ` [PATCH v1 2/2] signal: add procfd_signal() syscall Christian Brauner
2018-11-19 15:45 ` Andy Lutomirski
2018-11-19 15:57 ` Daniel Colascione
2018-11-19 18:39 ` Christian Brauner
2018-11-19 15:59 ` Daniel Colascione
2018-11-19 18:29 ` Christian Brauner
2018-11-19 19:02 ` Eric W. Biederman
2018-11-19 19:31 ` Christian Brauner
2018-11-19 19:39 ` Daniel Colascione
2018-11-19 17:10 ` Eugene Syromiatnikov
2018-11-19 18:23 ` Christian Brauner
2018-11-19 17:14 ` Eugene Syromiatnikov
2018-11-19 20:28 ` Aleksa Sarai
2018-11-19 20:55 ` Christian Brauner
2018-11-19 21:13 ` Christian Brauner
2018-11-19 21:18 ` Aleksa Sarai
2018-11-19 21:20 ` Christian Brauner
2018-11-19 21:21 ` Christian Brauner
2018-11-19 21:25 ` Aleksa Sarai
2018-11-19 21:26 ` Daniel Colascione
2018-11-19 21:36 ` Aleksa Sarai
2018-11-19 21:37 ` Christian Brauner
2018-11-19 21:41 ` Daniel Colascione
2018-11-20 4:59 ` Eric W. Biederman
2018-11-20 10:31 ` Christian Brauner
2018-11-21 21:39 ` Serge E. Hallyn
2018-11-19 21:23 ` Aleksa Sarai
2018-11-22 7:41 ` Serge E. Hallyn
2018-11-19 22:39 ` Tycho Andersen
2018-11-19 22:49 ` Daniel Colascione
2018-11-19 23:07 ` Tycho Andersen
2018-11-20 0:27 ` Andy Lutomirski
2018-11-20 0:32 ` Christian Brauner
2018-11-20 0:34 ` Andy Lutomirski
2018-11-20 0:49 ` Daniel Colascione
2018-11-22 7:48 ` Serge E. Hallyn
2018-11-19 23:35 ` kbuild test robot
2018-11-19 23:37 ` kbuild test robot
2018-11-19 23:45 ` Christian Brauner
2018-11-28 21:45 ` Joey Pabalinas
2018-11-28 22:05 ` Christian Brauner
2018-11-28 23:02 ` Joey Pabalinas
2018-11-19 10:32 ` [PATCH] procfd_signal.2: document procfd_signal syscall Christian Brauner
2018-11-20 13:29 ` Michael Kerrisk (man-pages)
2018-11-28 20:59 ` Florian Weimer
2018-11-28 21:12 ` Christian Brauner
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