#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"
static char *arg_directory = NULL;
+static char *arg_user = NULL;
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",
+ " -D --directory=NAME Root directory for the container\n"
+ " -u --user=USER Run the command under specified user or uid\n",
program_invocation_short_name);
return 0;
static const struct option options[] = {
{ "help", no_argument, NULL, 'h' },
{ "directory", required_argument, NULL, 'D' },
+ { "user", optional_argument, NULL, 'u' },
{ NULL, 0, NULL, 0 }
};
assert(argc >= 0);
assert(argv);
- while ((c = getopt_long(argc, argv, "+hD:", options, NULL)) >= 0) {
+ while ((c = getopt_long(argc, argv, "+hD:u:", options, NULL)) >= 0) {
switch (c) {
break;
+ case 'u':
+ free(arg_user);
+ if (!(arg_user = strdup(optarg))) {
+ log_error("Failed to duplicate user name.");
+ return -ENOMEM;
+ }
+
+ break;
+
case '?':
return -EINVAL;
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 },
- { "/proc/sys", "/proc/sys", "bind", NULL, MS_BIND }, /* Bind mount first */
- { "/proc/sys", "/proc/sys", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT }, /* Then, make it r/o */
- { "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY },
- { "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID },
- { "/dev/pts", "/dev/pts", "bind", NULL, MS_BIND },
- { "tmpfs", "/dev/.run", "tmpfs", "mode=755", MS_NOSUID|MS_NOEXEC|MS_NODEV },
+ { "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++) {
- char *where;
int t;
if (asprintf(&where, "%s/%s", dest, mount_table[k].where) < 0) {
where,
mount_table[k].type,
mount_table[k].flags,
- mount_table[k].options) < 0) {
+ mount_table[k].options) < 0 &&
+ mount_table[k].fatal) {
log_error("mount(%s) failed: %m", where);
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) {
+static int copy_devnodes(const char *dest, const char *console) {
static const char devnodes[] =
"null\0"
const char *d;
int r = 0, k;
- char *tty = NULL;
- dev_t tty_devnum;
mode_t u;
+ struct stat st;
+ char *from = NULL, *to = NULL;
+
+ assert(dest);
+ assert(console);
u = umask(0000);
NULSTR_FOREACH(d, devnodes) {
- char *from = NULL, *to = NULL;
- struct stat st;
+ from = to = NULL;
asprintf(&from, "/dev/%s", d);
asprintf(&to, "%s/dev/%s", dest, d);
free(from);
free(to);
+ from = to = NULL;
+
if (r == 0)
r = -ENOMEM;
if (errno != ENOENT) {
log_error("Failed to stat %s: %m", from);
-
if (r == 0)
r = -errno;
}
- } else {
- if (mknod(to, st.st_mode, st.st_rdev) < 0) {
- log_error("mknod(%s) failed: %m", dest);
+ } else if (!S_ISCHR(st.st_mode) && !S_ISBLK(st.st_mode)) {
- if (r == 0)
- r = -errno;
- }
+ 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 ((k = get_ctty(&tty, &tty_devnum)) < 0) {
- log_error("Failed to determine controlling tty: %s", strerror(-k));
+ if (stat(console, &st) < 0) {
+ log_error("Failed to stat %s: %m", console);
if (r == 0)
- r = k;
- } else {
- char *from = NULL, *to = NULL;
+ r = -errno;
- asprintf(&from, "/dev/%s", tty);
- asprintf(&to, "%s/dev/console", dest);
+ goto finish;
- if (!from || !to) {
- log_error("Out of memory");
+ } else if (!S_ISCHR(st.st_mode)) {
- if (r == 0)
- r = k;
- } else {
- /* We need to bind mount our own tty on
- * /dev/console, since ptys cannot be used
- * unless on a devpts file system. But to bind
- * mount it we first have to create a device
- * node where we can bind mount it on. This is
- * kinda ugly since the TTY will very likely
- * be owned by a user/group that does not
- * exist in the container. */
-
- if (mknod(to, S_IFCHR|0600, tty_devnum) < 0) {
- log_error("mknod for /dev/console failed: %m");
+ log_error("/dev/console is not a char device.");
+ if (r == 0)
+ r = -EIO;
- if (r == 0)
- r = -errno;
- }
+ goto finish;
+ }
- if (mount(from, to, "bind", MS_BIND|MS_RDONLY, NULL) < 0) {
- log_error("bind mount for /dev/console failed: %m");
+ if (asprintf(&to, "%s/dev/console", dest) < 0) {
- if (r == 0)
- r = -errno;
- }
- }
+ log_error("Out of memory");
+ if (r == 0)
+ r = -ENOMEM;
- free(from);
- free(to);
+ 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;
}
- free(tty);
+finish:
umask(u);
unsigned long l;
- for (l = 0; l <= MAX(63LU, (unsigned long) CAP_LAST_CAP); l ++) {
+ for (l = 0; l <= MAX(63LU, (unsigned long) CAP_LAST_CAP); l++) {
unsigned i;
for (i = 0; i < ELEMENTSOF(retain); i++)
/* If this capability is not known, EINVAL
* will be returned, let's ignore this. */
if (errno == EINVAL)
- continue;
+ break;
log_error("PR_CAPBSET_DROP failed: %m");
return -errno;
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;
+ 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();
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;
goto finish;
}
- log_info("Spawning namespace container on %s.", arg_directory);
+ 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, NULL)) < 0) {
log_error("clone() failed: %m");
}
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[] = {
- "HOME=/root",
"PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin",
+ NULL, /* TERM */
+ NULL, /* HOME */
+ NULL, /* USER */
+ NULL, /* LOGNAME */
NULL
};
- /* child */
+ 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) < 0)
+ 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;
goto child_fail;
}
+ umask(0002);
+
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("/root");
+ chdir(home ? home : "/root");
execle("/bin/bash", "-bash", NULL, (char**) envp);
}
_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:
- free(arg_directory);
+ 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 (pid > 0)
- kill(pid, SIGTERM);
+ if (newcg)
+ cg_kill_recursive_and_wait(SYSTEMD_CGROUP_CONTROLLER, newcg, true);
+
+ free(arg_directory);
+ free(oldcg);
+ free(newcg);
return r;
}