Messages in this thread | | | From | Christian Brauner <> | Subject | [PATCH v1 0/2] proc: allow signaling processes via file descriptors | Date | Mon, 19 Nov 2018 11:32:37 +0100 |
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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
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