/*-*- 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 <linux/fs.h> #include <systemd/sd-daemon.h> #include "log.h" #include "util.h" #include "missing.h" #include "cgroup-util.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, false)) < 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) { if (mount("/etc/localtime", where, "bind", MS_BIND, NULL) >= 0) 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 <= 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) { 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; } 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); 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 < LINE_MAX) { if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, LINE_MAX - 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 < LINE_MAX) { if ((k = read(master, out_buffer + out_buffer_full, LINE_MAX - 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", "container=systemd-nspawn", /* LXC sets container=lxc, so follow the scheme here */ NULL, /* TERM */ NULL, /* HOME */ NULL, /* USER */ NULL, /* LOGNAME */ 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(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 + 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_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; }