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/***
This file is part of systemd.
Copyright 2010 Lennart Poettering
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <fcntl.h>
#include <sched.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/wait.h>
#include "fd-util.h" /* _cleanup_close_ */
#include "path-util.h" /* prefix_roota */
static char **arg_parameters = NULL;
static int outer_child(
const char *directory,
const char *console,
int pid_socket) {
pid_t pid;
ssize_t l;
int r;
const char *to;
assert(directory);
assert(console);
assert(pid_socket >= 0);
r = open(console, O_RDWR, 0);
if (r < 0)
return log_error_errno(r, "Failed to open console: %m");
to = prefix_roota(directory, "/dev/console");
if (mount(console, to, NULL, MS_BIND, NULL) < 0)
return log_error_errno(errno, "mount /dev/console: %m");
if (chdir(directory) < 0)
return log_error_errno(errno, "Failed to chdir: %m");
if (chroot(".") < 0)
return log_error_errno(errno, "Failed to chroot: %m");
if (unshare(CLONE_NEWNS|CLONE_NEWPID) < 0)
return log_error_errno(errno, "unshare: %m");
pid = fork();
switch (pid) {
case -1:
return log_error_errno(errno, "Failed to fork inner child: %m");
case 0:
pid_socket = safe_close(pid_socket);
printf("a\n");
if (mount("proc", "/proc", "proc", MS_NOSUID|MS_NOEXEC|MS_NODEV, NULL) < 0)
return log_error_errno(errno, "mount /proc: %m");
printf("b\n");
execvp(arg_parameters[0], arg_parameters);
return -errno;
default:
l = send(pid_socket, &pid, sizeof(pid), MSG_NOSIGNAL);
if (l < 0)
return log_error_errno(errno, "Failed to send PID: %m");
if (l != sizeof(pid)) {
log_error("Short write while sending PID.");
return -EIO;
}
pid_socket = safe_close(pid_socket);
return 0;
}
}
static int run(const char *directory,
int master,
const char *console,
int *ret) {
pid_t pid;
_cleanup_close_pair_ int pid_socket_pair[2] = { -1, -1 };
int r;
ssize_t l;
if (socketpair(AF_UNIX, SOCK_SEQPACKET|SOCK_CLOEXEC, 0, pid_socket_pair) < 0)
return log_error_errno(errno, "Failed to create pid socket pair: %m");
pid = fork();
switch (pid) {
case -1:
return log_error_errno(errno, "clone() failed%s: %m",
errno == EINVAL ?
", do you have namespace support enabled in your kernel? (You need UTS, IPC, PID and NET namespacing built in)" : "");
case 0:
if (unshare(CLONE_NEWNS|CLONE_NEWUSER) < 0)
return log_error_errno(errno, "unshare: %m");
if (unshare(CLONE_NEWNS) < 0)
return log_error_errno(errno, "unshare: %m");
master = safe_close(master);
pid_socket_pair[0] = safe_close(pid_socket_pair[0]);
r = outer_child(directory,
console,
pid_socket_pair[1]);
if (r < 0)
_exit(EXIT_FAILURE);
_exit(EXIT_SUCCESS);
default:
pid_socket_pair[1] = safe_close(pid_socket_pair[1]);
printf("pid: %ld\n", (long)pid);
r = wait_for_terminate_and_warn("outer child", pid, NULL);
if (r != 0)
return r < 0 ? r : -EIO;
/* And now retrieve the PID of the inner child. */
l = recv(pid_socket_pair[0], &pid, sizeof pid, 0);
if (l < 0)
return log_error_errno(errno, "Failed to read inner child PID: %m");
if (l != sizeof pid) {
log_error("Short read while reading inner child PID.");
return -EIO;
}
printf("pid: %ld\n", (long)pid);
r = wait_for_terminate_and_warn("inner child", pid, NULL);
if (r < 0) {
/* We failed to wait for the container, or the container exited abnormally. */
return r;
} else {
*ret = r;
return 0;
}
}
}
int main(int argc, char *argv[]) {
char *console = NULL;
_cleanup_close_ int master = -1;
int r, ret = EXIT_SUCCESS;
char *arg_directory = NULL;
log_parse_environment();
log_open();
if (argc < 3)
return 2;
arg_directory = argv[1];
arg_parameters = &argv[2];
master = posix_openpt(O_RDWR|O_NOCTTY|O_CLOEXEC|O_NDELAY);
if (master < 0) {
r = log_error_errno(errno, "Failed to acquire pseudo tty: %m");
goto finish;
}
console = ptsname(master);
if (!console) {
r = log_error_errno(errno, "Failed to determine tty name: %m");
goto finish;
}
if (unlockpt(master) < 0) {
r = log_error_errno(errno, "Failed to unlock tty: %m");
goto finish;
}
/* for some reason removing this appends " (deleted)" to the entry in /proc/self/fd/ */
if (prctl(PR_SET_CHILD_SUBREAPER, 1) < 0) {
r = log_error_errno(errno, "Failed to become subreaper: %m");
goto finish;
}
r = run(arg_directory,
master,
console,
&ret);
finish:
return r < 0 ? EXIT_FAILURE : ret;
}
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