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Systemd/src/nspawn/nspawn.c

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/*-*- 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 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 <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 <linux/fs.h>
#include <sys/un.h>
#include <sys/socket.h>
#include <systemd/sd-daemon.h>
#include "log.h"
#include "util.h"
#include "mkdir.h"
#include "audit.h"
#include "missing.h"
#include "cgroup-util.h"
#include "strv.h"
#include "path-util.h"
#include "loopback-setup.h"
#include "sd-id128.h"
typedef enum LinkJournal {
LINK_NO,
LINK_AUTO,
LINK_HOST,
LINK_GUEST
} LinkJournal;
static char *arg_directory = NULL;
static char *arg_user = NULL;
static char **arg_controllers = NULL;
static char *arg_uuid = NULL;
static bool arg_private_network = false;
static bool arg_read_only = false;
static bool arg_boot = false;
static LinkJournal arg_link_journal = LINK_AUTO;
static uint64_t arg_retain =
(1ULL << CAP_CHOWN) |
(1ULL << CAP_DAC_OVERRIDE) |
(1ULL << CAP_DAC_READ_SEARCH) |
(1ULL << CAP_FOWNER) |
(1ULL << CAP_FSETID) |
(1ULL << CAP_IPC_OWNER) |
(1ULL << CAP_KILL) |
(1ULL << CAP_LEASE) |
(1ULL << CAP_LINUX_IMMUTABLE) |
(1ULL << CAP_NET_BIND_SERVICE) |
(1ULL << CAP_NET_BROADCAST) |
(1ULL << CAP_NET_RAW) |
(1ULL << CAP_SETGID) |
(1ULL << CAP_SETFCAP) |
(1ULL << CAP_SETPCAP) |
(1ULL << CAP_SETUID) |
(1ULL << CAP_SYS_ADMIN) |
(1ULL << CAP_SYS_CHROOT) |
(1ULL << CAP_SYS_NICE) |
(1ULL << CAP_SYS_PTRACE) |
(1ULL << CAP_SYS_TTY_CONFIG) |
(1ULL << CAP_SYS_RESOURCE);
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"
" -b --boot Boot up full system (i.e. invoke init)\n"
" -u --user=USER Run the command under specified user or uid\n"
" -C --controllers=LIST Put the container in specified comma-separated cgroup hierarchies\n"
" --uuid=UUID Set a specific machine UUID for the container\n"
" --private-network Disable network in container\n"
" --read-only Mount the root directory read-only\n"
" --capability=CAP In addition to the default, retain specified capability\n"
" --link-journal=MODE Link up guest journal, one of no, auto, guest, host\n"
" -j Equivalent to --link-journal=host\n",
program_invocation_short_name);
return 0;
}
static int parse_argv(int argc, char *argv[]) {
enum {
ARG_PRIVATE_NETWORK = 0x100,
ARG_UUID,
ARG_READ_ONLY,
ARG_CAPABILITY,
ARG_LINK_JOURNAL
};
static const struct option options[] = {
{ "help", no_argument, NULL, 'h' },
{ "directory", required_argument, NULL, 'D' },
{ "user", required_argument, NULL, 'u' },
{ "controllers", required_argument, NULL, 'C' },
{ "private-network", no_argument, NULL, ARG_PRIVATE_NETWORK },
{ "boot", no_argument, NULL, 'b' },
{ "uuid", required_argument, NULL, ARG_UUID },
{ "read-only", no_argument, NULL, ARG_READ_ONLY },
{ "capability", required_argument, NULL, ARG_CAPABILITY },
{ "link-journal", required_argument, NULL, ARG_LINK_JOURNAL },
{ NULL, 0, NULL, 0 }
};
int c;
assert(argc >= 0);
assert(argv);
while ((c = getopt_long(argc, argv, "+hD:u:C:bj", options, NULL)) >= 0) {
switch (c) {
case 'h':
help();
return 0;
case 'D':
free(arg_directory);
arg_directory = canonicalize_file_name(optarg);
if (!arg_directory) {
log_error("Failed to canonicalize 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 'C':
strv_free(arg_controllers);
arg_controllers = strv_split(optarg, ",");
if (!arg_controllers) {
log_error("Failed to split controllers list.");
return -ENOMEM;
}
strv_uniq(arg_controllers);
break;
case ARG_PRIVATE_NETWORK:
arg_private_network = true;
break;
case 'b':
arg_boot = true;
break;
case ARG_UUID:
arg_uuid = optarg;
break;
case ARG_READ_ONLY:
arg_read_only = true;
break;
case ARG_CAPABILITY: {
char *state, *word;
size_t length;
FOREACH_WORD_SEPARATOR(word, length, optarg, ",", state) {
cap_value_t cap;
char *t;
t = strndup(word, length);
if (!t)
return log_oom();
if (cap_from_name(t, &cap) < 0) {
log_error("Failed to parse capability %s.", t);
free(t);
return -EINVAL;
}
free(t);
arg_retain |= 1ULL << (uint64_t) cap;
}
break;
}
case 'j':
arg_link_journal = LINK_GUEST;
break;
case ARG_LINK_JOURNAL:
if (streq(optarg, "auto"))
arg_link_journal = LINK_AUTO;
else if (streq(optarg, "no"))
arg_link_journal = LINK_NO;
else if (streq(optarg, "guest"))
arg_link_journal = LINK_GUEST;
else if (streq(optarg, "host"))
arg_link_journal = LINK_HOST;
else {
log_error("Failed to parse link journal mode %s", optarg);
return -EINVAL;
}
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|MS_STRICTATIME, true },
{ "/dev/pts", "/dev/pts", "bind", NULL, MS_BIND, true },
{ "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME, 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_oom();
if (r == 0)
r = -ENOMEM;
break;
}
t = path_is_mount_point(where, false);
if (t < 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_label(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);
}
return r;
}
static int setup_timezone(const char *dest) {
char *where;
assert(dest);
/* Fix the timezone, if possible */
if (asprintf(&where, "%s/etc/localtime", dest) < 0)
return log_oom();
if (mount("/etc/localtime", where, "bind", MS_BIND, NULL) >= 0)
mount("/etc/localtime", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
free(where);
if (asprintf(&where, "%s/etc/timezone", dest) < 0)
return log_oom();
if (mount("/etc/timezone", where, "bind", MS_BIND, NULL) >= 0)
mount("/etc/timezone", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
free(where);
return 0;
}
static int setup_resolv_conf(const char *dest) {
char *where;
assert(dest);
if (arg_private_network)
return 0;
/* Fix resolv.conf, if possible */
if (asprintf(&where, "%s/etc/resolv.conf", dest) < 0) {
return log_oom();
}
if (mount("/etc/resolv.conf", where, "bind", MS_BIND, NULL) >= 0)
mount("/etc/resolv.conf", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
free(where);
return 0;
}
static int copy_devnodes(const char *dest) {
static const char devnodes[] =
"null\0"
"zero\0"
"full\0"
"random\0"
"urandom\0"
"tty\0"
"ptmx\0"
"rtc0\0";
const char *d;
int r = 0;
mode_t u;
assert(dest);
u = umask(0000);
NULSTR_FOREACH(d, devnodes) {
struct stat st;
char *from = NULL, *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);
}
umask(u);
return r;
}
static int setup_dev_console(const char *dest, const char *console) {
struct stat st;
char *to = NULL;
int r;
mode_t u;
assert(dest);
assert(console);
u = umask(0000);
if (stat(console, &st) < 0) {
log_error("Failed to stat %s: %m", console);
r = -errno;
goto finish;
} else if (!S_ISCHR(st.st_mode)) {
log_error("/dev/console is not a char device.");
r = -EIO;
goto finish;
}
r = chmod_and_chown(console, 0600, 0, 0);
if (r < 0) {
log_error("Failed to correct access mode for TTY: %s", strerror(-r));
goto finish;
}
if (asprintf(&to, "%s/dev/console", dest) < 0) {
r = log_oom();
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");
r = -errno;
goto finish;
}
if (mount(console, to, "bind", MS_BIND, NULL) < 0) {
log_error("Bind mount for /dev/console failed: %m");
r = -errno;
goto finish;
}
finish:
free(to);
umask(u);
return r;
}
static int setup_kmsg(const char *dest, int kmsg_socket) {
char *from = NULL, *to = NULL;
int r, fd, k;
mode_t u;
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int))];
} control;
struct msghdr mh;
struct cmsghdr *cmsg;
assert(dest);
assert(kmsg_socket >= 0);
u = umask(0000);
/* We create the kmsg FIFO as /dev/kmsg, but immediately
* delete it after bind mounting it to /proc/kmsg. While FIFOs
* on the reading side behave very similar to /proc/kmsg,
* their writing side behaves differently from /dev/kmsg in
* that writing blocks when nothing is reading. In order to
* avoid any problems with containers deadlocking due to this
* we simply make /dev/kmsg unavailable to the container. */
if (asprintf(&from, "%s/dev/kmsg", dest) < 0) {
r = log_oom();
goto finish;
}
if (asprintf(&to, "%s/proc/kmsg", dest) < 0) {
r = log_oom();
goto finish;
}
if (mkfifo(from, 0600) < 0) {
log_error("mkfifo() for /dev/kmsg failed: %m");
r = -errno;
goto finish;
}
r = chmod_and_chown(from, 0600, 0, 0);
if (r < 0) {
log_error("Failed to correct access mode for /dev/kmsg: %s", strerror(-r));
goto finish;
}
if (mount(from, to, "bind", MS_BIND, NULL) < 0) {
log_error("Bind mount for /proc/kmsg failed: %m");
r = -errno;
goto finish;
}
fd = open(from, O_RDWR|O_NDELAY|O_CLOEXEC);
if (fd < 0) {
log_error("Failed to open fifo: %m");
r = -errno;
goto finish;
}
zero(mh);
zero(control);
mh.msg_control = &control;
mh.msg_controllen = sizeof(control);
cmsg = CMSG_FIRSTHDR(&mh);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
mh.msg_controllen = cmsg->cmsg_len;
/* Store away the fd in the socket, so that it stays open as
* long as we run the child */
k = sendmsg(kmsg_socket, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
close_nointr_nofail(fd);
if (k < 0) {
log_error("Failed to send FIFO fd: %m");
r = -errno;
goto finish;
}
/* And now make the FIFO unavailable as /dev/kmsg... */
unlink(from);
finish:
free(from);
free(to);
umask(u);
return r;
}
static int setup_hostname(void) {
char *hn;
int r = 0;
hn = path_get_file_name(arg_directory);
if (hn) {
hn = strdup(hn);
if (!hn)
return -ENOMEM;
hostname_cleanup(hn);
if (!isempty(hn))
if (sethostname(hn, strlen(hn)) < 0)
r = -errno;
free(hn);
}
return r;
}
static int setup_journal(const char *directory) {
sd_id128_t machine_id;
char *p = NULL, *b = NULL, *l, *q = NULL, *d = NULL;
int r;
if (arg_link_journal == LINK_NO)
return 0;
p = strappend(directory, "/etc/machine-id");
if (!p) {
r = log_oom();
goto finish;
}
r = read_one_line_file(p, &b);
if (r == -ENOENT && arg_link_journal == LINK_AUTO) {
r = 0;
goto finish;
} else if (r < 0) {
log_error("Failed to read machine ID: %s", strerror(-r));
return r;
}
l = strstrip(b);
if (isempty(l) && arg_link_journal == LINK_AUTO) {
r = 0;
goto finish;
}
/* Verify validaty */
r = sd_id128_from_string(l, &machine_id);
if (r < 0) {
log_error("Failed to parse machine ID: %s", strerror(-r));
goto finish;
}
free(p);
p = strappend("/var/log/journal/", l);
q = strjoin(directory, "/var/log/journal/", l, NULL);
if (!p || !q) {
r = log_oom();
goto finish;
}
if (path_is_mount_point(p, false) > 0 ||
path_is_mount_point(q, false) > 0) {
if (arg_link_journal != LINK_AUTO) {
log_error("Journal already a mount point, refusing.");
r = -EEXIST;
goto finish;
}
r = 0;
goto finish;
}
r = readlink_and_make_absolute(p, &d);
if (r >= 0) {
if ((arg_link_journal == LINK_GUEST ||
arg_link_journal == LINK_AUTO) &&
path_equal(d, q)) {
mkdir_p(q, 0755);
r = 0;
goto finish;
}
if (unlink(p) < 0) {
log_error("Failed to remove symlink %s: %m", p);
r = -errno;
goto finish;
}
} else if (r == -EINVAL) {
if (arg_link_journal == LINK_GUEST &&
rmdir(p) < 0) {
if (errno == ENOTDIR)
log_error("%s already exists and is neither symlink nor directory.", p);
else {
log_error("Failed to remove %s: %m", p);
r = -errno;
}
goto finish;
}
} else if (r != -ENOENT) {
log_error("readlink(%s) failed: %m", p);
goto finish;
}
if (arg_link_journal == LINK_GUEST) {
if (symlink(q, p) < 0) {
log_error("Failed to symlink %s to %s: %m", q, p);
r = -errno;
goto finish;
}
mkdir_p(q, 0755);
r = 0;
goto finish;
}
if (arg_link_journal == LINK_HOST) {
r = mkdir_p(p, 0755);
if (r < 0) {
log_error("Failed to create %s: %m", p);
goto finish;
}
} else if (access(p, F_OK) < 0) {
r = 0;
goto finish;
}
if (dir_is_empty(q) == 0) {
log_error("%s not empty.", q);
r = -ENOTEMPTY;
goto finish;
}
r = mkdir_p(q, 0755);
if (r < 0) {
log_error("Failed to create %s: %m", q);
goto finish;
}
if (mount(p, q, "bind", MS_BIND, NULL) < 0) {
log_error("Failed to bind mount journal from host into guest: %m");
r = -errno;
goto finish;
}
r = 0;
finish:
free(p);
free(q);
free(d);
free(b);
return r;
}
static int drop_capabilities(void) {
return capability_bounding_set_drop(~arg_retain, false);
}
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;
}
static int process_pty(int master, sigset_t *mask) {
char in_buffer[LINE_MAX], out_buffer[LINE_MAX];
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);
signal_fd = signalfd(-1, mask, SFD_NONBLOCK|SFD_CLOEXEC);
if (signal_fd < 0) {
log_error("signalfd(): %m");
r = -errno;
goto finish;
}
ep = epoll_create1(EPOLL_CLOEXEC);
if (ep < 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;
nfds = epoll_wait(ep, ev, ELEMENTSOF(ev), -1);
if (nfds < 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;
n = read(signal_fd, &sfsi, sizeof(sfsi));
if (n != 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 < LINE_MAX) {
k = read(STDIN_FILENO, in_buffer + in_buffer_full, LINE_MAX - in_buffer_full);
if (k < 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) {
k = write(master, in_buffer, in_buffer_full);
if (k < 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 < LINE_MAX) {
k = read(master, out_buffer + out_buffer_full, LINE_MAX - out_buffer_full);
if (k < 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) {
k = write(STDOUT_FILENO, out_buffer, out_buffer_full);
if (k < 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;
char **controller = 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;
int kmsg_socket_pair[2] = { -1, -1 };
log_parse_environment();
log_open();
r = parse_argv(argc, argv);
if (r <= 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;
}
k = cg_get_by_pid(SYSTEMD_CGROUP_CONTROLLER, 0, &oldcg);
if (k < 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;
}
k = cg_create_and_attach(SYSTEMD_CGROUP_CONTROLLER, newcg, 0);
if (k < 0) {
log_error("Failed to create cgroup: %s", strerror(-k));
goto finish;
}
STRV_FOREACH(controller, arg_controllers) {
k = cg_create_and_attach(*controller, newcg, 0);
if (k < 0)
log_warning("Failed to create cgroup in controller %s: %s", *controller, strerror(-k));
}
master = posix_openpt(O_RDWR|O_NOCTTY|O_CLOEXEC|O_NDELAY);
if (master < 0) {
log_error("Failed to acquire pseudo tty: %m");
goto finish;
}
console = ptsname(master);
if (!console) {
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;
}
if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, kmsg_socket_pair) < 0) {
log_error("Failed to create kmsg socket pair");
goto finish;
}
assert_se(sigemptyset(&mask) == 0);
sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1);
assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0);
pid = syscall(__NR_clone, SIGCHLD|CLONE_NEWIPC|CLONE_NEWNS|CLONE_NEWPID|CLONE_NEWUTS|(arg_private_network ? CLONE_NEWNET : 0), NULL);
if (pid < 0) {
if (errno == EINVAL)
log_error("clone() failed, do you have namespace support enabled in your kernel? (You need UTS, IPC, PID and NET namespacing built in): %m");
else
log_error("clone() failed: %m");
goto finish;
}
if (pid == 0) {
/* child */
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",
"container=systemd-nspawn", /* LXC sets container=lxc, so follow the scheme here */
NULL, /* TERM */
NULL, /* HOME */
NULL, /* USER */
NULL, /* LOGNAME */
NULL, /* container_uuid */
NULL
};
envp[2] = strv_find_prefix(environ, "TERM=");
close_nointr_nofail(master);
close_nointr(STDIN_FILENO);
close_nointr(STDOUT_FILENO);
close_nointr(STDERR_FILENO);
close_all_fds(&kmsg_socket_pair[1], 1);
reset_all_signal_handlers();
assert_se(sigemptyset(&mask) == 0);
assert_se(sigprocmask(SIG_SETMASK, &mask, NULL) == 0);
if (open_terminal(console, O_RDWR) != STDIN_FILENO ||
dup2(STDIN_FILENO, STDOUT_FILENO) != STDOUT_FILENO ||
dup2(STDIN_FILENO, STDERR_FILENO) != STDERR_FILENO)
goto child_fail;
if (setsid() < 0) {
log_error("setsid() failed: %m");
goto child_fail;
}
if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0) {
log_error("PR_SET_PDEATHSIG failed: %m");
goto child_fail;
}
/* Mark / as private, in case somebody marked it shared */
if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) < 0) {
log_error("MS_PRIVATE|MS_REC failed: %m");
goto child_fail;
}
/* Turn directory into bind mount */
if (mount(arg_directory, arg_directory, "bind", MS_BIND, NULL) < 0) {
log_error("Failed to make bind mount.");
goto child_fail;
}
if (arg_read_only)
if (mount(arg_directory, arg_directory, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL) < 0) {
log_error("Failed to make read-only.");
goto child_fail;
}
if (mount_all(arg_directory) < 0)
goto child_fail;
if (copy_devnodes(arg_directory) < 0)
goto child_fail;
if (setup_dev_console(arg_directory, console) < 0)
goto child_fail;
if (setup_kmsg(arg_directory, kmsg_socket_pair[1]) < 0)
goto child_fail;
close_nointr_nofail(kmsg_socket_pair[1]);
if (setup_timezone(arg_directory) < 0)
goto child_fail;
if (setup_resolv_conf(arg_directory) < 0)
goto child_fail;
if (setup_journal(arg_directory) < 0)
goto child_fail;
if (chdir(arg_directory) < 0) {
log_error("chdir(%s) failed: %m", arg_directory);
goto child_fail;
}
if (mount(arg_directory, "/", "bind", MS_MOVE, NULL) < 0) {
log_error("mount(MS_BIND) 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) {
log_error("drop_capabilities() failed: %m");
goto child_fail;
}
if (arg_user) {
if (get_user_creds((const char**)&arg_user, &uid, &gid, &home, NULL) < 0) {
log_error("get_user_creds() failed: %m");
goto child_fail;
}
if (mkdir_parents_label(home, 0775) < 0) {
log_error("mkdir_parents_label() failed: %m");
goto child_fail;
}
if (mkdir_safe_label(home, 0775, uid, gid) < 0) {
log_error("mkdir_safe_label() 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 + 3), "HOME=%s", home ? home: "/root") < 0) ||
(asprintf((char**)(envp + 4), "USER=%s", arg_user ? arg_user : "root") < 0) ||
(asprintf((char**)(envp + 5), "LOGNAME=%s", arg_user ? arg_user : "root") < 0)) {
log_oom();
goto child_fail;
}
if (arg_uuid) {
if (asprintf((char**)(envp + 6), "container_uuid=%s", arg_uuid) < 0) {
log_oom();
goto child_fail;
}
}
setup_hostname();
if (arg_boot) {
char **a;
size_t l;
/* Automatically search for the init system */
l = 1 + argc - optind;
a = newa(char*, l + 1);
memcpy(a + 1, argv + optind, l * sizeof(char*));
a[0] = (char*) "/usr/lib/systemd/systemd";
execve(a[0], a, (char**) envp);
a[0] = (char*) "/lib/systemd/systemd";
execve(a[0], a, (char**) envp);
a[0] = (char*) "/sbin/init";
execve(a[0], a, (char**) envp);
} else 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);
close_pipe(kmsg_socket_pair);
if (oldcg)
cg_attach(SYSTEMD_CGROUP_CONTROLLER, oldcg, 0);
if (newcg)
cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, newcg, true);
free(arg_directory);
strv_free(arg_controllers);
free(oldcg);
free(newcg);
return r;
}
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