From 9e91e62a7c16348793b7d402eae749a72e1f541e Mon Sep 17 00:00:00 2001 From: Pavel Tikhomirov Date: Wed, 22 Jun 2022 12:12:07 +0300 Subject: [PATCH] criu-ns: capture controlling tty When we are restoring in new pidns we specifically do setsid() from criu-ns init so that sids of restored tasks are non-zero in this pidns and on next dump CRIU would not have problems with zero sids, see [1]. But after this CRIU tries to inherit and setup a tty for the restored process, and it fails to set it's process group via TIOCSPGRP to be a foreground group for it's tty, because tty already is a controlling tty for other session (which we had before setsid). So to make it restore we need to reset tty to be a controlling tty of criu-ns init via TIOCSCTTY before calling criu. Else when restoring first time via criu-ns (from criu-ns dump) we get: Error (criu/tty.c:689): tty: Failed to set group 40816 on 0: Inappropriate ioctl for device https://github.com/checkpoint-restore/criu/issues/232 [1] v2: add why and what comment in code, set controlling tty only for --shell-job and fail if stdin is not a tty. Fixes: #1893 Signed-off-by: Pavel Tikhomirov --- scripts/criu-ns | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/scripts/criu-ns b/scripts/criu-ns index 1217c3dcdf..d51e7772c0 100755 --- a/scripts/criu-ns +++ b/scripts/criu-ns @@ -4,6 +4,8 @@ import ctypes.util import errno import sys import os +import fcntl +import termios # constants for unshare CLONE_NEWNS = 0x00020000 @@ -124,6 +126,16 @@ def wrap_restore(): criu_pid = os.fork() if criu_pid == 0: os.setsid() + # Set stdin tty to be a controlling tty of our new session, this is + # required by --shell-job option, as for it CRIU would try to set a + # process group of restored root task to be a foreground group on the + # terminal. + if '--shell-job' in restore_args or '-j' in restore_args: + if os.isatty(sys.stdin.fileno()): + fcntl.ioctl(sys.stdin.fileno(), termios.TIOCSCTTY, 1) + else: + raise OSError(errno.EINVAL, 'The stdin is not a tty for a --shell-job') + _mount_new_proc() run_criu(restore_args)