picnoir
/
Systemd
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
Systemd/src/nspawn.c

885 lines
30 KiB
C
Raw Blame History

/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
/***
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 General Public License as published by
the Free Software Foundation; either version 2 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
General Public License for more details.
You should have received a copy of the GNU General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <signal.h>
#include <sched.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/syscall.h>
#include <sys/mount.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <errno.h>
#include <sys/prctl.h>
#include <sys/capability.h>
#include <getopt.h>
#include <sys/epoll.h>
#include <termios.h>
#include <sys/signalfd.h>
#include <grp.h>
#include "log.h"
#include "util.h"
#include "missing.h"
#include "cgroup-util.h"
#include "sd-daemon.h"
#include "strv.h"
#include "loopback-setup.h"
static char *arg_directory = NULL;
static char *arg_user = NULL;
static bool arg_private_network = false;
static int help(void) {
printf("%s [OPTIONS...] [PATH] [ARGUMENTS...]\n\n"
"Spawn a minimal namespace container for debugging, testing and building.\n\n"
" -h --help Show this help\n"
" -D --directory=NAME Root directory for the container\n"
" -u --user=USER Run the command under specified user or uid\n"
" --private-network Disable network in container\n",
program_invocation_short_name);
return 0;
}
static int parse_argv(int argc, char *argv[]) {
enum {
ARG_PRIVATE_NETWORK = 0x100
};
static const struct option options[] = {
{ "help", no_argument, NULL, 'h' },
{ "directory", required_argument, NULL, 'D' },
{ "user", required_argument, NULL, 'u' },
{ "private-network", no_argument, NULL, ARG_PRIVATE_NETWORK },
{ NULL, 0, NULL, 0 }
};
int c;
assert(argc >= 0);
assert(argv);
while ((c = getopt_long(argc, argv, "+hD:u:", options, NULL)) >= 0) {
switch (c) {
case 'h':
help();
return 0;
case 'D':
free(arg_directory);
if (!(arg_directory = strdup(optarg))) {
log_error("Failed to duplicate root directory.");
return -ENOMEM;
}
break;
case 'u':
free(arg_user);
if (!(arg_user = strdup(optarg))) {
log_error("Failed to duplicate user name.");
return -ENOMEM;
}
break;
case ARG_PRIVATE_NETWORK:
arg_private_network = true;
break;
case '?':
return -EINVAL;
default:
log_error("Unknown option code %c", c);
return -EINVAL;
}
}
return 1;
}
static int mount_all(const char *dest) {
typedef struct MountPoint {
const char *what;
const char *where;
const char *type;
const char *options;
unsigned long flags;
bool fatal;
} MountPoint;
static const MountPoint mount_table[] = {
{ "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
{ "/proc/sys", "/proc/sys", "bind", NULL, MS_BIND, true }, /* Bind mount first */
{ "/proc/sys", "/proc/sys", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */
{ "/sys", "/sys", "bind", NULL, MS_BIND, true }, /* Bind mount first */
{ "/sys", "/sys", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */
{ "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID, true },
{ "/dev/pts", "/dev/pts", "bind", NULL, MS_BIND, true },
{ "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV, true },
#ifdef HAVE_SELINUX
{ "/sys/fs/selinux", "/sys/fs/selinux", "bind", NULL, MS_BIND, false }, /* Bind mount first */
{ "/sys/fs/selinux", "/sys/fs/selinux", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, false }, /* Then, make it r/o */
#endif
};
unsigned k;
int r = 0;
char *where;
for (k = 0; k < ELEMENTSOF(mount_table); k++) {
int t;
if (asprintf(&where, "%s/%s", dest, mount_table[k].where) < 0) {
log_error("Out of memory");
if (r == 0)
r = -ENOMEM;
break;
}
if ((t = path_is_mount_point(where)) < 0) {
log_error("Failed to detect whether %s is a mount point: %s", where, strerror(-t));
free(where);
if (r == 0)
r = t;
continue;
}
mkdir_p(where, 0755);
if (mount(mount_table[k].what,
where,
mount_table[k].type,
mount_table[k].flags,
mount_table[k].options) < 0 &&
mount_table[k].fatal) {
log_error("mount(%s) failed: %m", where);
if (r == 0)
r = -errno;
}
free(where);
}
/* Fix the timezone, if possible */
if (asprintf(&where, "%s/%s", dest, "/etc/localtime") >= 0) {
mount("/etc/localtime", where, "bind", MS_BIND, NULL);
mount("/etc/localtime", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
free(where);
}
return r;
}
static int copy_devnodes(const char *dest, const char *console) {
static const char devnodes[] =
"null\0"
"zero\0"
"full\0"
"random\0"
"urandom\0"
"tty\0"
"ptmx\0"
"kmsg\0"
"rtc0\0";
const char *d;
int r = 0, k;
mode_t u;
struct stat st;
char *from = NULL, *to = NULL;
assert(dest);
assert(console);
u = umask(0000);
NULSTR_FOREACH(d, devnodes) {
from = to = NULL;
asprintf(&from, "/dev/%s", d);
asprintf(&to, "%s/dev/%s", dest, d);
if (!from || !to) {
log_error("Failed to allocate devnode path");
free(from);
free(to);
from = to = NULL;
if (r == 0)
r = -ENOMEM;
break;
}
if (stat(from, &st) < 0) {
if (errno != ENOENT) {
log_error("Failed to stat %s: %m", from);
if (r == 0)
r = -errno;
}
} else if (!S_ISCHR(st.st_mode) && !S_ISBLK(st.st_mode)) {
log_error("%s is not a char or block device, cannot copy.", from);
if (r == 0)
r = -EIO;
} else if (mknod(to, st.st_mode, st.st_rdev) < 0) {
log_error("mknod(%s) failed: %m", dest);
if (r == 0)
r = -errno;
}
free(from);
free(to);
}
if (stat(console, &st) < 0) {
log_error("Failed to stat %s: %m", console);
if (r == 0)
r = -errno;
goto finish;
} else if (!S_ISCHR(st.st_mode)) {
log_error("/dev/console is not a char device.");
if (r == 0)
r = -EIO;
goto finish;
}
if (asprintf(&to, "%s/dev/console", dest) < 0) {
log_error("Out of memory");
if (r == 0)
r = -ENOMEM;
goto finish;
}
/* We need to bind mount the right tty to /dev/console since
* ptys can only exist on pts file systems. To have something
* to bind mount things on we create a device node first, that
* has the right major/minor (note that the major minor
* doesn't actually matter here, since we mount it over
* anyway). */
if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0)
log_error("mknod for /dev/console failed: %m");
if (mount(console, to, "bind", MS_BIND, NULL) < 0) {
log_error("bind mount for /dev/console failed: %m");
if (r == 0)
r = -errno;
}
free(to);
if ((k = chmod_and_chown(console, 0600, 0, 0)) < 0) {
log_error("Failed to correct access mode for TTY: %s", strerror(-k));
if (r == 0)
r = k;
}
finish:
umask(u);
return r;
}
static int drop_capabilities(void) {
static const unsigned long retain[] = {
CAP_CHOWN,
CAP_DAC_OVERRIDE,
CAP_DAC_READ_SEARCH,
CAP_FOWNER,
CAP_FSETID,
CAP_IPC_OWNER,
CAP_KILL,
CAP_LEASE,
CAP_LINUX_IMMUTABLE,
CAP_NET_BIND_SERVICE,
CAP_NET_BROADCAST,
CAP_NET_RAW,
CAP_SETGID,
CAP_SETFCAP,
CAP_SETPCAP,
CAP_SETUID,
CAP_SYS_ADMIN,
CAP_SYS_CHROOT,
CAP_SYS_NICE,
CAP_SYS_PTRACE,
CAP_SYS_TTY_CONFIG
};
unsigned long l;
for (l = 0; l <= MAX(63LU, (unsigned long) CAP_LAST_CAP); l++) {
unsigned i;
for (i = 0; i < ELEMENTSOF(retain); i++)
if (retain[i] == l)
break;
if (i < ELEMENTSOF(retain))
continue;
if (prctl(PR_CAPBSET_DROP, l) < 0) {
/* If this capability is not known, EINVAL
* will be returned, let's ignore this. */
if (errno == EINVAL)
break;
log_error("PR_CAPBSET_DROP failed: %m");
return -errno;
}
}
return 0;
}
static int is_os_tree(const char *path) {
int r;
char *p;
/* We use /bin/sh as flag file if something is an OS */
if (asprintf(&p, "%s/bin/sh", path) < 0)
return -ENOMEM;
r = access(p, F_OK);
free(p);
return r < 0 ? 0 : 1;
}
#define BUFFER_SIZE 1024
static int process_pty(int master, sigset_t *mask) {
char in_buffer[BUFFER_SIZE], out_buffer[BUFFER_SIZE];
size_t in_buffer_full = 0, out_buffer_full = 0;
struct epoll_event stdin_ev, stdout_ev, master_ev, signal_ev;
bool stdin_readable = false, stdout_writable = false, master_readable = false, master_writable = false;
int ep = -1, signal_fd = -1, r;
fd_nonblock(STDIN_FILENO, 1);
fd_nonblock(STDOUT_FILENO, 1);
fd_nonblock(master, 1);
if ((signal_fd = signalfd(-1, mask, SFD_NONBLOCK|SFD_CLOEXEC)) < 0) {
log_error("signalfd(): %m");
r = -errno;
goto finish;
}
if ((ep = epoll_create1(EPOLL_CLOEXEC)) < 0) {
log_error("Failed to create epoll: %m");
r = -errno;
goto finish;
}
zero(stdin_ev);
stdin_ev.events = EPOLLIN|EPOLLET;
stdin_ev.data.fd = STDIN_FILENO;
zero(stdout_ev);
stdout_ev.events = EPOLLOUT|EPOLLET;
stdout_ev.data.fd = STDOUT_FILENO;
zero(master_ev);
master_ev.events = EPOLLIN|EPOLLOUT|EPOLLET;
master_ev.data.fd = master;
zero(signal_ev);
signal_ev.events = EPOLLIN;
signal_ev.data.fd = signal_fd;
if (epoll_ctl(ep, EPOLL_CTL_ADD, STDIN_FILENO, &stdin_ev) < 0 ||
epoll_ctl(ep, EPOLL_CTL_ADD, STDOUT_FILENO, &stdout_ev) < 0 ||
epoll_ctl(ep, EPOLL_CTL_ADD, master, &master_ev) < 0 ||
epoll_ctl(ep, EPOLL_CTL_ADD, signal_fd, &signal_ev) < 0) {
log_error("Failed to regiser fds in epoll: %m");
r = -errno;
goto finish;
}
for (;;) {
struct epoll_event ev[16];
ssize_t k;
int i, nfds;
if ((nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1)) < 0) {
if (errno == EINTR || errno == EAGAIN)
continue;
log_error("epoll_wait(): %m");
r = -errno;
goto finish;
}
assert(nfds >= 1);
for (i = 0; i < nfds; i++) {
if (ev[i].data.fd == STDIN_FILENO) {
if (ev[i].events & (EPOLLIN|EPOLLHUP))
stdin_readable = true;
} else if (ev[i].data.fd == STDOUT_FILENO) {
if (ev[i].events & (EPOLLOUT|EPOLLHUP))
stdout_writable = true;
} else if (ev[i].data.fd == master) {
if (ev[i].events & (EPOLLIN|EPOLLHUP))
master_readable = true;
if (ev[i].events & (EPOLLOUT|EPOLLHUP))
master_writable = true;
} else if (ev[i].data.fd == signal_fd) {
struct signalfd_siginfo sfsi;
ssize_t n;
if ((n = read(signal_fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) {
if (n >= 0) {
log_error("Failed to read from signalfd: invalid block size");
r = -EIO;
goto finish;
}
if (errno != EINTR && errno != EAGAIN) {
log_error("Failed to read from signalfd: %m");
r = -errno;
goto finish;
}
} else {
if (sfsi.ssi_signo == SIGWINCH) {
struct winsize ws;
/* The window size changed, let's forward that. */
if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
ioctl(master, TIOCSWINSZ, &ws);
} else {
r = 0;
goto finish;
}
}
}
}
while ((stdin_readable && in_buffer_full <= 0) ||
(master_writable && in_buffer_full > 0) ||
(master_readable && out_buffer_full <= 0) ||
(stdout_writable && out_buffer_full > 0)) {
if (stdin_readable && in_buffer_full < BUFFER_SIZE) {
if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, BUFFER_SIZE - in_buffer_full)) < 0) {
if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
stdin_readable = false;
else {
log_error("read(): %m");
r = -errno;
goto finish;
}
} else
in_buffer_full += (size_t) k;
}
if (master_writable && in_buffer_full > 0) {
if ((k = write(master, in_buffer, in_buffer_full)) < 0) {
if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
master_writable = false;
else {
log_error("write(): %m");
r = -errno;
goto finish;
}
} else {
assert(in_buffer_full >= (size_t) k);
memmove(in_buffer, in_buffer + k, in_buffer_full - k);
in_buffer_full -= k;
}
}
if (master_readable && out_buffer_full < BUFFER_SIZE) {
if ((k = read(master, out_buffer + out_buffer_full, BUFFER_SIZE - out_buffer_full)) < 0) {
if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
master_readable = false;
else {
log_error("read(): %m");
r = -errno;
goto finish;
}
} else
out_buffer_full += (size_t) k;
}
if (stdout_writable && out_buffer_full > 0) {
if ((k = write(STDOUT_FILENO, out_buffer, out_buffer_full)) < 0) {
if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO)
stdout_writable = false;
else {
log_error("write(): %m");
r = -errno;
goto finish;
}
} else {
assert(out_buffer_full >= (size_t) k);
memmove(out_buffer, out_buffer + k, out_buffer_full - k);
out_buffer_full -= k;
}
}
}
}
finish:
if (ep >= 0)
close_nointr_nofail(ep);
if (signal_fd >= 0)
close_nointr_nofail(signal_fd);
return r;
}
int main(int argc, char *argv[]) {
pid_t pid = 0;
int r = EXIT_FAILURE, k;
char *oldcg = NULL, *newcg = NULL;
int master = -1;
const char *console = NULL;
struct termios saved_attr, raw_attr;
sigset_t mask;
bool saved_attr_valid = false;
struct winsize ws;
log_parse_environment();
log_open();
if ((r = parse_argv(argc, argv)) <= 0)
goto finish;
if (arg_directory) {
char *p;
p = path_make_absolute_cwd(arg_directory);
free(arg_directory);
arg_directory = p;
} else
arg_directory = get_current_dir_name();
if (!arg_directory) {
log_error("Failed to determine path");
goto finish;
}
path_kill_slashes(arg_directory);
if (geteuid() != 0) {
log_error("Need to be root.");
goto finish;
}
if (sd_booted() <= 0) {
log_error("Not running on a systemd system.");
goto finish;
}
if (path_equal(arg_directory, "/")) {
log_error("Spawning container on root directory not supported.");
goto finish;
}
if (is_os_tree(arg_directory) <= 0) {
log_error("Directory %s doesn't look like an OS root directory. Refusing.", arg_directory);
goto finish;
}
if ((k = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &oldcg)) < 0) {
log_error("Failed to determine current cgroup: %s", strerror(-k));
goto finish;
}
if (asprintf(&newcg, "%s/nspawn-%lu", oldcg, (unsigned long) getpid()) < 0) {
log_error("Failed to allocate cgroup path.");
goto finish;
}
if ((k = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, newcg, 0)) < 0) {
log_error("Failed to create cgroup: %s", strerror(-k));
goto finish;
}
if ((master = posix_openpt(O_RDWR|O_NOCTTY|O_CLOEXEC|O_NDELAY)) < 0) {
log_error("Failed to acquire pseudo tty: %m");
goto finish;
}
if (!(console = ptsname(master))) {
log_error("Failed to determine tty name: %m");
goto finish;
}
log_info("Spawning namespace container on %s (console is %s).", arg_directory, console);
if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0)
ioctl(master, TIOCSWINSZ, &ws);
if (unlockpt(master) < 0) {
log_error("Failed to unlock tty: %m");
goto finish;
}
if (tcgetattr(STDIN_FILENO, &saved_attr) < 0) {
log_error("Failed to get terminal attributes: %m");
goto finish;
}
saved_attr_valid = true;
raw_attr = saved_attr;
cfmakeraw(&raw_attr);
raw_attr.c_lflag &= ~ECHO;
if (tcsetattr(STDIN_FILENO, TCSANOW, &raw_attr) < 0) {
log_error("Failed to set terminal attributes: %m");
goto finish;
}
assert_se(sigemptyset(&mask) == 0);
sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1);
assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0);
if ((pid = syscall(__NR_clone, SIGCHLD|CLONE_NEWIPC|CLONE_NEWNS|CLONE_NEWPID|CLONE_NEWUTS|(arg_private_network ? CLONE_NEWNET : 0), NULL)) < 0) {
log_error("clone() failed: %m");
goto finish;
}
if (pid == 0) {
/* child */
const char *hn;
const char *home = NULL;
uid_t uid = (uid_t) -1;
gid_t gid = (gid_t) -1;
const char *envp[] = {
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
NULL, /* TERM */
NULL, /* HOME */
NULL, /* USER */
NULL, /* LOGNAME */
NULL
};
envp[1] = strv_find_prefix(environ, "TERM=");
close_nointr_nofail(master);
close_nointr(STDIN_FILENO);
close_nointr(STDOUT_FILENO);
close_nointr(STDERR_FILENO);
close_all_fds(NULL, 0);
reset_all_signal_handlers();
assert_se(sigemptyset(&mask) == 0);
assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
if (setsid() < 0)
goto child_fail;
if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0)
goto child_fail;
/* Mark / as private, in case somebody marked it shared */
if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) < 0)
goto child_fail;
if (mount_all(arg_directory) < 0)
goto child_fail;
if (copy_devnodes(arg_directory, console) < 0)
goto child_fail;
if (chdir(arg_directory) < 0) {
log_error("chdir(%s) failed: %m", arg_directory);
goto child_fail;
}
if (open_terminal("dev/console", O_RDWR) != STDIN_FILENO ||
dup2(STDIN_FILENO, STDOUT_FILENO) != STDOUT_FILENO ||
dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO)
goto child_fail;
if (mount(arg_directory, "/", "bind", MS_BIND|MS_MOVE, NULL) < 0) {
log_error("mount(MS_MOVE) failed: %m");
goto child_fail;
}
if (chroot(".") < 0) {
log_error("chroot() failed: %m");
goto child_fail;
}
if (chdir("/") < 0) {
log_error("chdir() failed: %m");
goto child_fail;
}
umask(0022);
loopback_setup();
if (drop_capabilities() < 0)
goto child_fail;
if (arg_user) {
if (get_user_creds((const char**)&arg_user, &uid, &gid, &home) < 0) {
log_error("get_user_creds() failed: %m");
goto child_fail;
}
if (mkdir_parents(home, 0775) < 0) {
log_error("mkdir_parents() failed: %m");
goto child_fail;
}
if (safe_mkdir(home, 0775, uid, gid) < 0) {
log_error("safe_mkdir() failed: %m");
goto child_fail;
}
if (initgroups((const char*)arg_user, gid) < 0) {
log_error("initgroups() failed: %m");
goto child_fail;
}
if (setresgid(gid, gid, gid) < 0) {
log_error("setregid() failed: %m");
goto child_fail;
}
if (setresuid(uid, uid, uid) < 0) {
log_error("setreuid() failed: %m");
goto child_fail;
}
}
if ((asprintf((char**)(envp + 2), "HOME=%s", home? home: "/root") < 0) ||
(asprintf((char**)(envp + 3), "USER=%s", arg_user? arg_user : "root") < 0) ||
(asprintf((char**)(envp + 4), "LOGNAME=%s", arg_user? arg_user : "root") < 0)) {
log_error("Out of memory");
goto child_fail;
}
if ((hn = file_name_from_path(arg_directory)))
sethostname(hn, strlen(hn));
if (argc > optind)
execvpe(argv[optind], argv + optind, (char**) envp);
else {
chdir(home ? home : "/root");
execle("/bin/bash", "-bash", NULL, (char**) envp);
}
log_error("execv() failed: %m");
child_fail:
_exit(EXIT_FAILURE);
}
if (process_pty(master, &mask) < 0)
goto finish;
if (saved_attr_valid) {
tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr);
saved_attr_valid = false;
}
r = wait_for_terminate_and_warn(argc > optind ? argv[optind] : "bash", pid);
if (r < 0)
r = EXIT_FAILURE;
finish:
if (saved_attr_valid)
tcsetattr(STDIN_FILENO, TCSANOW, &saved_attr);
if (master >= 0)
close_nointr_nofail(master);
if (oldcg)
cg_attach(SYSTEMD_CGROUP_CONTROLLER, oldcg, 0);
if (newcg)
cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, newcg, true);
free(arg_directory);
free(oldcg);
free(newcg);
return r;
}
Reference in New Issue View Git Blame Copy Permalink