src/lxc/start.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #define _GNU_SOURCE
  25 #include "config.h"
  26
  27 #include <alloca.h>
  28 #include <dirent.h>
  29 #include <errno.h>
  30 #include <fcntl.h>
  31 #include <grp.h>
  32 #include <poll.h>
  33 #include <signal.h>
  34 #include <stdio.h>
  35 #include <stdlib.h>
  36 #include <string.h>
  37 #include <unistd.h>
  38 #include <sys/file.h>
  39 #include <sys/mount.h>
  40 #include <sys/param.h>
  41 #include <sys/prctl.h>
  42 #include <sys/socket.h>
  43 #include <sys/stat.h>
  44 #include <sys/syscall.h>
  45 #include <sys/types.h>
  46 #include <sys/un.h>
  47 #include <sys/wait.h>
  48
  49 #if HAVE_SYS_CAPABILITY_H
  50 #include <sys/capability.h>
  51 #endif
  52
  53 #ifndef HAVE_DECL_PR_CAPBSET_DROP
  54 #define PR_CAPBSET_DROP 24
  55 #endif
  56
  57 #ifndef HAVE_DECL_PR_SET_NO_NEW_PRIVS
  58 #define PR_SET_NO_NEW_PRIVS 38
  59 #endif
  60
  61 #ifndef HAVE_DECL_PR_GET_NO_NEW_PRIVS
  62 #define PR_GET_NO_NEW_PRIVS 39
  63 #endif
  64
  65 #include "af_unix.h"
  66 #include "bdev.h"
  67 #include "caps.h"
  68 #include "cgroup.h"
  69 #include "commands.h"
  70 #include "conf.h"
  71 #include "console.h"
  72 #include "error.h"
  73 #include "log.h"
  74 #include "lxclock.h"
  75 #include "lxcseccomp.h"
  76 #include "lxcutmp.h"
  77 #include "mainloop.h"
  78 #include "monitor.h"
  79 #include "namespace.h"
  80 #include "start.h"
  81 #include "sync.h"
  82 #include "utils.h"
  83 #include "lsm/lsm.h"
  84
  85 lxc_log_define(lxc_start, lxc);
  86
  87 const struct ns_info ns_info[LXC_NS_MAX] = {
  88         [LXC_NS_MNT] = {"mnt", CLONE_NEWNS},
  89         [LXC_NS_PID] = {"pid", CLONE_NEWPID},
  90         [LXC_NS_UTS] = {"uts", CLONE_NEWUTS},
  91         [LXC_NS_IPC] = {"ipc", CLONE_NEWIPC},
  92         [LXC_NS_USER] = {"user", CLONE_NEWUSER},
  93         [LXC_NS_NET] = {"net", CLONE_NEWNET},
  94         [LXC_NS_CGROUP] = {"cgroup", CLONE_NEWCGROUP}
  95 };
  96
  97 extern void mod_all_rdeps(struct lxc_container *c, bool inc);
  98 static bool do_destroy_container(struct lxc_conf *conf);
  99 static int lxc_rmdir_onedev_wrapper(void *data);
 100 static void lxc_destroy_container_on_signal(struct lxc_handler *handler,
 101                                             const char *name);
 102
 103 static void print_top_failing_dir(const char *path)
 104 {
 105         size_t len = strlen(path);
 106         char *copy = alloca(len + 1), *p, *e, saved;
 107         strcpy(copy, path);
 108
 109         p = copy;
 110         e = copy + len;
 111         while (p < e) {
 112                 while (p < e && *p == '/')
 113                         p++;
 114                 while (p < e && *p != '/')
 115                         p++;
 116                 saved = *p;
 117                 *p = '\0';
 118                 if (access(copy, X_OK)) {
 119                         SYSERROR("could not access %s.  Please grant it 'x' " \
 120                               "access, or add an ACL for the container root.",
 121                               copy);
 122                         return;
 123                 }
 124                 *p = saved;
 125         }
 126 }
 127
 128 static void close_ns(int ns_fd[LXC_NS_MAX]) {
 129         int i;
 130
 131         for (i = 0; i < LXC_NS_MAX; i++) {
 132                 if (ns_fd[i] > -1) {
 133                         close(ns_fd[i]);
 134                         ns_fd[i] = -1;
 135                 }
 136         }
 137 }
 138
 139 /*
 140  * preserve_ns: open /proc/@pid/ns/@ns for each namespace specified
 141  * in clone_flags.
 142  * Return true on success, false on failure.  On failure, leave an error
 143  * message in *errmsg, which caller must free.
 144  */
 145 static bool preserve_ns(int ns_fd[LXC_NS_MAX], int clone_flags, pid_t pid,
 146                         char **errmsg)
 147 {
 148         int i, ret;
 149         char path[MAXPATHLEN];
 150
 151         for (i = 0; i < LXC_NS_MAX; i++)
 152                 ns_fd[i] = -1;
 153
 154         snprintf(path, MAXPATHLEN, "/proc/%d/ns", pid);
 155         if (access(path, X_OK)) {
 156                 if (asprintf(errmsg, "Kernel does not support setns.") == -1)
 157                         *errmsg = NULL;
 158                 return false;
 159         }
 160
 161         for (i = 0; i < LXC_NS_MAX; i++) {
 162                 if ((clone_flags & ns_info[i].clone_flag) == 0)
 163                         continue;
 164                 snprintf(path, MAXPATHLEN, "/proc/%d/ns/%s", pid,
 165                          ns_info[i].proc_name);
 166                 ns_fd[i] = open(path, O_RDONLY | O_CLOEXEC);
 167                 if (ns_fd[i] < 0)
 168                         goto error;
 169         }
 170
 171         return true;
 172
 173 error:
 174         if (errno == ENOENT) {
 175                 ret = asprintf(errmsg, "Kernel does not support setns for %s",
 176                         ns_info[i].proc_name);
 177         } else {
 178                 ret = asprintf(errmsg, "Failed to open %s: %s",
 179                         path, strerror(errno));
 180         }
 181         if (ret == -1)
 182                 *errmsg = NULL;
 183         close_ns(ns_fd);
 184         return false;
 185 }
 186
 187 static int attach_ns(const int ns_fd[LXC_NS_MAX]) {
 188         int i;
 189
 190         for (i = 0; i < LXC_NS_MAX; i++) {
 191                 if (ns_fd[i] < 0)
 192                         continue;
 193
 194                 if (setns(ns_fd[i], 0) != 0)
 195                         goto error;
 196         }
 197         return 0;
 198
 199 error:
 200         SYSERROR("failed to set namespace '%s'", ns_info[i].proc_name);
 201         return -1;
 202 }
 203
 204 static int match_fd(int fd)
 205 {
 206         return (fd == 0 || fd == 1 || fd == 2);
 207 }
 208
 209 /*
 210  * Check for any fds we need to close
 211  * * if fd_to_ignore != -1, then if we find that fd open we will ignore it.
 212  * * By default we warn about open fds we find.
 213  * * If closeall is true, we will close open fds.
 214  * * If lxc-start was passed "-C", then conf->close_all_fds will be true,
 215  *     in which case we also close all open fds.
 216  * * A daemonized container will always pass closeall=true.
 217  */
 218 int lxc_check_inherited(struct lxc_conf *conf, bool closeall, int fd_to_ignore)
 219 {
 220         struct dirent *direntp;
 221         int fd, fddir;
 222         DIR *dir;
 223
 224         if (conf && conf->close_all_fds)
 225                 closeall = true;
 226
 227 restart:
 228         dir = opendir("/proc/self/fd");
 229         if (!dir) {
 230                 WARN("failed to open directory: %m");
 231                 return -1;
 232         }
 233
 234         fddir = dirfd(dir);
 235
 236         while ((direntp = readdir(dir))) {
 237                 if (!direntp)
 238                         break;
 239
 240                 if (!strcmp(direntp->d_name, "."))
 241                         continue;
 242
 243                 if (!strcmp(direntp->d_name, ".."))
 244                         continue;
 245
 246                 fd = atoi(direntp->d_name);
 247
 248                 if (fd == fddir || fd == lxc_log_fd || fd == fd_to_ignore)
 249                         continue;
 250
 251                 if (current_config && fd == current_config->logfd)
 252                         continue;
 253
 254                 if (match_fd(fd))
 255                         continue;
 256
 257                 if (closeall) {
 258                         close(fd);
 259                         closedir(dir);
 260                         INFO("closed inherited fd %d", fd);
 261                         goto restart;
 262                 }
 263                 WARN("inherited fd %d", fd);
 264         }
 265
 266         /*
 267          * only enable syslog at this point to avoid the above logging function
 268          * to open a new fd and make the check_inherited function enter an
 269          * infinite loop.
 270          */
 271         lxc_log_enable_syslog();
 272
 273         closedir(dir); /* cannot fail */
 274         return 0;
 275 }
 276
 277 static int setup_signal_fd(sigset_t *oldmask)
 278 {
 279         sigset_t mask;
 280         int fd;
 281
 282         /* Block everything except serious error signals */
 283         if (sigfillset(&mask) ||
 284             sigdelset(&mask, SIGILL) ||
 285             sigdelset(&mask, SIGSEGV) ||
 286             sigdelset(&mask, SIGBUS) ||
 287             sigdelset(&mask, SIGWINCH) ||
 288             sigprocmask(SIG_BLOCK, &mask, oldmask)) {
 289                 SYSERROR("failed to set signal mask");
 290                 return -1;
 291         }
 292
 293         fd = signalfd(-1, &mask, 0);
 294         if (fd < 0) {
 295                 SYSERROR("failed to create the signal fd");
 296                 return -1;
 297         }
 298
 299         if (fcntl(fd, F_SETFD, FD_CLOEXEC)) {
 300                 SYSERROR("failed to set sigfd to close-on-exec");
 301                 close(fd);
 302                 return -1;
 303         }
 304
 305         DEBUG("sigchild handler set");
 306
 307         return fd;
 308 }
 309
 310 static int signal_handler(int fd, uint32_t events, void *data,
 311                           struct lxc_epoll_descr *descr)
 312 {
 313         struct signalfd_siginfo siginfo;
 314         siginfo_t info;
 315         int ret;
 316         pid_t *pid = data;
 317         bool init_died = false;
 318
 319         ret = read(fd, &siginfo, sizeof(siginfo));
 320         if (ret < 0) {
 321                 ERROR("failed to read signal info");
 322                 return -1;
 323         }
 324
 325         if (ret != sizeof(siginfo)) {
 326                 ERROR("unexpected siginfo size");
 327                 return -1;
 328         }
 329
 330         // check whether init is running
 331         info.si_pid = 0;
 332         ret = waitid(P_PID, *pid, &info, WEXITED | WNOWAIT | WNOHANG);
 333         if (ret == 0 && info.si_pid == *pid) {
 334                 init_died = true;
 335         }
 336
 337         if (siginfo.ssi_signo != SIGCHLD) {
 338                 kill(*pid, siginfo.ssi_signo);
 339                 INFO("forwarded signal %d to pid %d", siginfo.ssi_signo, *pid);
 340                 return init_died ? 1 : 0;
 341         }
 342
 343         if (siginfo.ssi_code == CLD_STOPPED ||
 344             siginfo.ssi_code == CLD_CONTINUED) {
 345                 INFO("container init process was stopped/continued");
 346                 return init_died ? 1 : 0;
 347         }
 348
 349         /* more robustness, protect ourself from a SIGCHLD sent
 350          * by a process different from the container init
 351          */
 352         if (siginfo.ssi_pid != *pid) {
 353                 WARN("invalid pid for SIGCHLD");
 354                 return init_died ? 1 : 0;
 355         }
 356
 357         DEBUG("container init process exited");
 358         return 1;
 359 }
 360
 361 int lxc_set_state(const char *name, struct lxc_handler *handler, lxc_state_t state)
 362 {
 363         handler->state = state;
 364         lxc_monitor_send_state(name, state, handler->lxcpath);
 365         return 0;
 366 }
 367
 368 int lxc_poll(const char *name, struct lxc_handler *handler)
 369 {
 370         int sigfd = handler->sigfd;
 371         int pid = handler->pid;
 372         struct lxc_epoll_descr descr;
 373
 374         if (lxc_mainloop_open(&descr)) {
 375                 ERROR("failed to create mainloop");
 376                 goto out_sigfd;
 377         }
 378
 379         if (lxc_mainloop_add_handler(&descr, sigfd, signal_handler, &pid)) {
 380                 ERROR("failed to add handler for the signal");
 381                 goto out_mainloop_open;
 382         }
 383
 384         if (lxc_console_mainloop_add(&descr, handler->conf)) {
 385                 ERROR("failed to add console handler to mainloop");
 386                 goto out_mainloop_open;
 387         }
 388
 389         if (lxc_cmd_mainloop_add(name, &descr, handler)) {
 390                 ERROR("failed to add command handler to mainloop");
 391                 goto out_mainloop_open;
 392         }
 393
 394         if (handler->conf->need_utmp_watch) {
 395                 #if HAVE_SYS_CAPABILITY_H
 396                 if (lxc_utmp_mainloop_add(&descr, handler)) {
 397                         ERROR("failed to add utmp handler to mainloop");
 398                         goto out_mainloop_open;
 399                 }
 400                 #else
 401                         DEBUG("not starting utmp handler as cap_sys_boot cannot be dropped without capabilities support");
 402                 #endif
 403         }
 404
 405         return lxc_mainloop(&descr, -1);
 406
 407 out_mainloop_open:
 408         lxc_mainloop_close(&descr);
 409 out_sigfd:
 410         close(sigfd);
 411         return -1;
 412 }
 413
 414 struct lxc_handler *lxc_init(const char *name, struct lxc_conf *conf, const char *lxcpath)
 415 {
 416         int i;
 417         struct lxc_handler *handler;
 418
 419         handler = malloc(sizeof(*handler));
 420         if (!handler)
 421                 return NULL;
 422
 423         memset(handler, 0, sizeof(*handler));
 424
 425         handler->ttysock[0] = handler->ttysock[1] = -1;
 426         handler->conf = conf;
 427         handler->lxcpath = lxcpath;
 428         handler->pinfd = -1;
 429
 430         for (i = 0; i < LXC_NS_MAX; i++)
 431                 handler->nsfd[i] = -1;
 432
 433         lsm_init();
 434
 435         handler->name = strdup(name);
 436         if (!handler->name) {
 437                 ERROR("failed to allocate memory");
 438                 goto out_free;
 439         }
 440
 441         if (lxc_cmd_init(name, handler, lxcpath))
 442                 goto out_free_name;
 443
 444         if (lxc_read_seccomp_config(conf) != 0) {
 445                 ERROR("failed loading seccomp policy");
 446                 goto out_close_maincmd_fd;
 447         }
 448
 449         /* Begin by setting the state to STARTING */
 450         if (lxc_set_state(name, handler, STARTING)) {
 451                 ERROR("failed to set state '%s'", lxc_state2str(STARTING));
 452                 goto out_close_maincmd_fd;
 453         }
 454
 455         /* Start of environment variable setup for hooks */
 456         if (name && setenv("LXC_NAME", name, 1)) {
 457                 SYSERROR("failed to set environment variable for container name");
 458         }
 459         if (conf->rcfile && setenv("LXC_CONFIG_FILE", conf->rcfile, 1)) {
 460                 SYSERROR("failed to set environment variable for config path");
 461         }
 462         if (conf->rootfs.mount && setenv("LXC_ROOTFS_MOUNT", conf->rootfs.mount, 1)) {
 463                 SYSERROR("failed to set environment variable for rootfs mount");
 464         }
 465         if (conf->rootfs.path && setenv("LXC_ROOTFS_PATH", conf->rootfs.path, 1)) {
 466                 SYSERROR("failed to set environment variable for rootfs mount");
 467         }
 468         if (conf->console.path && setenv("LXC_CONSOLE", conf->console.path, 1)) {
 469                 SYSERROR("failed to set environment variable for console path");
 470         }
 471         if (conf->console.log_path && setenv("LXC_CONSOLE_LOGPATH", conf->console.log_path, 1)) {
 472                 SYSERROR("failed to set environment variable for console log");
 473         }
 474         if (setenv("LXC_CGNS_AWARE", "1", 1)) {
 475                 SYSERROR("failed to set LXC_CGNS_AWARE environment variable");
 476         }
 477         /* End of environment variable setup for hooks */
 478
 479         if (run_lxc_hooks(name, "pre-start", conf, handler->lxcpath, NULL)) {
 480                 ERROR("failed to run pre-start hooks for container '%s'.", name);
 481                 goto out_aborting;
 482         }
 483
 484         /* the signal fd has to be created before forking otherwise
 485          * if the child process exits before we setup the signal fd,
 486          * the event will be lost and the command will be stuck */
 487         handler->sigfd = setup_signal_fd(&handler->oldmask);
 488         if (handler->sigfd < 0) {
 489                 ERROR("failed to set sigchild fd handler");
 490                 goto out_delete_tty;
 491         }
 492
 493         /* do this after setting up signals since it might unblock SIGWINCH */
 494         if (lxc_console_create(conf)) {
 495                 ERROR("failed to create console");
 496                 goto out_restore_sigmask;
 497         }
 498
 499         if (ttys_shift_ids(conf) < 0) {
 500                 ERROR("Failed to shift tty into container");
 501                 goto out_restore_sigmask;
 502         }
 503
 504         INFO("'%s' is initialized", name);
 505         return handler;
 506
 507 out_restore_sigmask:
 508         sigprocmask(SIG_SETMASK, &handler->oldmask, NULL);
 509 out_delete_tty:
 510         lxc_delete_tty(&conf->tty_info);
 511 out_aborting:
 512         lxc_set_state(name, handler, ABORTING);
 513 out_close_maincmd_fd:
 514         close(conf->maincmd_fd);
 515         conf->maincmd_fd = -1;
 516 out_free_name:
 517         free(handler->name);
 518         handler->name = NULL;
 519 out_free:
 520         free(handler);
 521         return NULL;
 522 }
 523
 524 void lxc_fini(const char *name, struct lxc_handler *handler)
 525 {
 526         int i, rc;
 527         pid_t self = getpid();
 528         char *namespaces[LXC_NS_MAX+1];
 529         size_t namespace_count = 0;
 530
 531         /* The STOPPING state is there for future cleanup code
 532          * which can take awhile
 533          */
 534         lxc_set_state(name, handler, STOPPING);
 535
 536         for (i = 0; i < LXC_NS_MAX; i++) {
 537                 if (handler->nsfd[i] != -1) {
 538                         rc = asprintf(&namespaces[namespace_count], "%s:/proc/%d/fd/%d",
 539                                       ns_info[i].proc_name, self, handler->nsfd[i]);
 540                         if (rc == -1) {
 541                                 SYSERROR("failed to allocate memory");
 542                                 break;
 543                         }
 544                         ++namespace_count;
 545                 }
 546         }
 547         namespaces[namespace_count] = NULL;
 548
 549         if (handler->conf->reboot && setenv("LXC_TARGET", "reboot", 1)) {
 550                 SYSERROR("failed to set environment variable for stop target");
 551         }
 552         if (!handler->conf->reboot && setenv("LXC_TARGET", "stop", 1)) {
 553                 SYSERROR("failed to set environment variable for stop target");
 554         }
 555
 556         if (run_lxc_hooks(name, "stop", handler->conf, handler->lxcpath, namespaces))
 557                 ERROR("failed to run stop hooks for container '%s'.", name);
 558
 559         while (namespace_count--)
 560                 free(namespaces[namespace_count]);
 561         for (i = 0; i < LXC_NS_MAX; i++) {
 562                 if (handler->nsfd[i] != -1) {
 563                         close(handler->nsfd[i]);
 564                         handler->nsfd[i] = -1;
 565                 }
 566         }
 567         lxc_set_state(name, handler, STOPPED);
 568
 569         if (run_lxc_hooks(name, "post-stop", handler->conf, handler->lxcpath, NULL)) {
 570                 ERROR("failed to run post-stop hooks for container '%s'.", name);
 571                 if (handler->conf->reboot) {
 572                         WARN("Container will be stopped instead of rebooted.");
 573                         handler->conf->reboot = 0;
 574                         setenv("LXC_TARGET", "stop", 1);
 575                 }
 576         }
 577
 578         /* reset mask set by setup_signal_fd */
 579         if (sigprocmask(SIG_SETMASK, &handler->oldmask, NULL))
 580                 WARN("failed to restore sigprocmask");
 581
 582         lxc_console_delete(&handler->conf->console);
 583         lxc_delete_tty(&handler->conf->tty_info);
 584         close(handler->conf->maincmd_fd);
 585         handler->conf->maincmd_fd = -1;
 586         free(handler->name);
 587         if (handler->ttysock[0] != -1) {
 588                 close(handler->ttysock[0]);
 589                 close(handler->ttysock[1]);
 590         }
 591
 592         if (handler->conf->ephemeral == 1 && handler->conf->reboot != 1)
 593                 lxc_destroy_container_on_signal(handler, name);
 594
 595         cgroup_destroy(handler);
 596         free(handler);
 597 }
 598
 599 void lxc_abort(const char *name, struct lxc_handler *handler)
 600 {
 601         int ret, status;
 602
 603         lxc_set_state(name, handler, ABORTING);
 604         if (handler->pid > 0)
 605                 kill(handler->pid, SIGKILL);
 606         while ((ret = waitpid(-1, &status, 0)) > 0) ;
 607 }
 608
 609 #include <sys/reboot.h>
 610 #include <linux/reboot.h>
 611
 612 /*
 613  * reboot(LINUX_REBOOT_CMD_CAD_ON) will return -EINVAL
 614  * in a child pid namespace if container reboot support exists.
 615  * Otherwise, it will either succeed or return -EPERM.
 616  */
 617 static int container_reboot_supported(void *arg)
 618 {
 619         int *cmd = arg;
 620         int ret;
 621
 622         ret = reboot(*cmd);
 623         if (ret == -1 && errno == EINVAL)
 624                 return 1;
 625         return 0;
 626 }
 627
 628 static int must_drop_cap_sys_boot(struct lxc_conf *conf)
 629 {
 630         FILE *f;
 631         int ret, cmd, v, flags;
 632         long stack_size = 4096;
 633         void *stack = alloca(stack_size);
 634         int status;
 635         pid_t pid;
 636
 637         f = fopen("/proc/sys/kernel/ctrl-alt-del", "r");
 638         if (!f) {
 639                 DEBUG("failed to open /proc/sys/kernel/ctrl-alt-del");
 640                 return 1;
 641         }
 642
 643         ret = fscanf(f, "%d", &v);
 644         fclose(f);
 645         if (ret != 1) {
 646                 DEBUG("Failed to read /proc/sys/kernel/ctrl-alt-del");
 647                 return 1;
 648         }
 649         cmd = v ? LINUX_REBOOT_CMD_CAD_ON : LINUX_REBOOT_CMD_CAD_OFF;
 650
 651         flags = CLONE_NEWPID | SIGCHLD;
 652         if (!lxc_list_empty(&conf->id_map))
 653                 flags |= CLONE_NEWUSER;
 654
 655 #ifdef __ia64__
 656         pid = __clone2(container_reboot_supported, stack, stack_size, flags,  &cmd);
 657 #else
 658         stack += stack_size;
 659         pid = clone(container_reboot_supported, stack, flags, &cmd);
 660 #endif
 661         if (pid < 0) {
 662                 if (flags & CLONE_NEWUSER)
 663                         ERROR("failed to clone (%#x): %s (includes CLONE_NEWUSER)", flags, strerror(errno));
 664                 else
 665                         ERROR("failed to clone (%#x): %s", flags, strerror(errno));
 666                 return -1;
 667         }
 668         if (wait(&status) < 0) {
 669                 SYSERROR("unexpected wait error: %m");
 670                 return -1;
 671         }
 672
 673         if (WEXITSTATUS(status) != 1)
 674                 return 1;
 675
 676         return 0;
 677 }
 678
 679 /*
 680  * netpipe is used in the unprivileged case to transfer the ifindexes
 681  * from parent to child
 682  */
 683 static int netpipe = -1;
 684
 685 static inline int count_veths(struct lxc_list *network)
 686 {
 687         struct lxc_list *iterator;
 688         struct lxc_netdev *netdev;
 689         int count = 0;
 690
 691         lxc_list_for_each(iterator, network) {
 692                 netdev = iterator->elem;
 693                 if (netdev->type != LXC_NET_VETH)
 694                         continue;
 695                 count++;
 696         }
 697         return count;
 698 }
 699
 700 static int read_unpriv_netifindex(struct lxc_list *network)
 701 {
 702         struct lxc_list *iterator;
 703         struct lxc_netdev *netdev;
 704
 705         if (netpipe == -1)
 706                 return 0;
 707         lxc_list_for_each(iterator, network) {
 708                 netdev = iterator->elem;
 709                 if (netdev->type != LXC_NET_VETH)
 710                         continue;
 711                 if (!(netdev->name = malloc(IFNAMSIZ))) {
 712                         ERROR("Out of memory");
 713                         close(netpipe);
 714                         return -1;
 715                 }
 716                 if (read(netpipe, netdev->name, IFNAMSIZ) != IFNAMSIZ) {
 717                         close(netpipe);
 718                         return -1;
 719                 }
 720         }
 721         close(netpipe);
 722         return 0;
 723 }
 724
 725 static int do_start(void *data)
 726 {
 727         struct lxc_list *iterator;
 728         struct lxc_handler *handler = data;
 729         int devnull_fd = -1, ret;
 730         char path[PATH_MAX];
 731
 732         if (sigprocmask(SIG_SETMASK, &handler->oldmask, NULL)) {
 733                 SYSERROR("failed to set sigprocmask");
 734                 return -1;
 735         }
 736
 737         /* This prctl must be before the synchro, so if the parent
 738          * dies before we set the parent death signal, we will detect
 739          * its death with the synchro right after, otherwise we have
 740          * a window where the parent can exit before we set the pdeath
 741          * signal leading to a unsupervized container.
 742          */
 743         if (prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0)) {
 744                 SYSERROR("failed to set pdeath signal");
 745                 return -1;
 746         }
 747
 748         lxc_sync_fini_parent(handler);
 749
 750         /* don't leak the pinfd to the container */
 751         if (handler->pinfd >= 0) {
 752                 close(handler->pinfd);
 753         }
 754
 755         if (lxc_sync_wait_parent(handler, LXC_SYNC_STARTUP))
 756                 return -1;
 757
 758         /* Unshare CLONE_NEWNET after CLONE_NEWUSER  - see
 759           https://github.com/lxc/lxd/issues/1978 */
 760         if ((handler->clone_flags & (CLONE_NEWNET | CLONE_NEWUSER)) ==
 761                         (CLONE_NEWNET | CLONE_NEWUSER)) {
 762                 ret = unshare(CLONE_NEWNET);
 763                 if (ret < 0) {
 764                         SYSERROR("Error unsharing network namespace");
 765                         goto out_warn_father;
 766                 }
 767         }
 768
 769         /* Tell the parent task it can begin to configure the
 770          * container and wait for it to finish
 771          */
 772         if (lxc_sync_barrier_parent(handler, LXC_SYNC_CONFIGURE))
 773                 return -1;
 774
 775         if (read_unpriv_netifindex(&handler->conf->network) < 0)
 776                 goto out_warn_father;
 777
 778         /*
 779          * if we are in a new user namespace, become root there to have
 780          * privilege over our namespace. When using lxc-execute we default to root,
 781          * but this can be overriden using the lxc.init_uid and lxc.init_gid
 782          * configuration options.
 783          */
 784         if (!lxc_list_empty(&handler->conf->id_map)) {
 785                 gid_t new_gid = 0;
 786                 if (handler->conf->is_execute && handler->conf->init_gid)
 787                         new_gid = handler->conf->init_gid;
 788
 789                 uid_t new_uid = 0;
 790                 if (handler->conf->is_execute && handler->conf->init_uid)
 791                         new_uid = handler->conf->init_uid;
 792
 793                 NOTICE("switching to gid/uid %d/%d in new user namespace", new_gid, new_uid);
 794                 if (setgid(new_gid)) {
 795                         SYSERROR("setgid");
 796                         goto out_warn_father;
 797                 }
 798                 if (setuid(new_uid)) {
 799                         SYSERROR("setuid");
 800                         goto out_warn_father;
 801                 }
 802                 if (setgroups(0, NULL)) {
 803                         SYSERROR("setgroups");
 804                         goto out_warn_father;
 805                 }
 806         }
 807
 808         if (access(handler->lxcpath, X_OK)) {
 809                 print_top_failing_dir(handler->lxcpath);
 810                 goto out_warn_father;
 811         }
 812
 813         #if HAVE_SYS_CAPABILITY_H
 814         if (handler->conf->need_utmp_watch) {
 815                 if (prctl(PR_CAPBSET_DROP, CAP_SYS_BOOT, 0, 0, 0)) {
 816                         SYSERROR("failed to remove CAP_SYS_BOOT capability");
 817                         goto out_warn_father;
 818                 }
 819                 DEBUG("Dropped cap_sys_boot");
 820         }
 821         #endif
 822
 823         ret = snprintf(path, sizeof(path), "%s/dev/null", handler->conf->rootfs.mount);
 824         if (ret < 0 || ret >= sizeof(path)) {
 825                 SYSERROR("sprintf'd too many chars");
 826                 goto out_warn_father;
 827         }
 828
 829         /* In order to checkpoint restore, we need to have everything in the
 830          * same mount namespace. However, some containers may not have a
 831          * reasonable /dev (in particular, they may not have /dev/null), so we
 832          * can't set init's std fds to /dev/null by opening it from inside the
 833          * container.
 834          *
 835          * If that's the case, fall back to using the host's /dev/null. This
 836          * means that migration won't work, but at least we won't spew output
 837          * where it isn't wanted.
 838          */
 839         if (handler->backgrounded && !handler->conf->autodev && access(path, F_OK) < 0) {
 840                 devnull_fd = open_devnull();
 841
 842                 if (devnull_fd < 0)
 843                         goto out_warn_father;
 844                 WARN("using host's /dev/null for container init's std fds, migraiton won't work");
 845         }
 846
 847         /* Setup the container, ip, names, utsname, ... */
 848         if (lxc_setup(handler)) {
 849                 ERROR("failed to setup the container");
 850                 goto out_warn_father;
 851         }
 852
 853         /* ask father to setup cgroups and wait for him to finish */
 854         if (lxc_sync_barrier_parent(handler, LXC_SYNC_CGROUP))
 855                 goto out_error;
 856
 857         /* Set the label to change to when we exec(2) the container's init */
 858         if (lsm_process_label_set(NULL, handler->conf, 1, 1) < 0)
 859                 goto out_warn_father;
 860
 861         /* Set PR_SET_NO_NEW_PRIVS after we changed the lsm label. If we do it
 862          * before we aren't allowed anymore. */
 863         if (handler->conf->no_new_privs) {
 864                 if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) {
 865                         SYSERROR("Could not set PR_SET_NO_NEW_PRIVS to block execve() gainable privileges.");
 866                         goto out_warn_father;
 867                 }
 868                 DEBUG("Set PR_SET_NO_NEW_PRIVS to block execve() gainable privileges.");
 869         }
 870
 871         /* Some init's such as busybox will set sane tty settings on stdin,
 872          * stdout, stderr which it thinks is the console. We already set them
 873          * the way we wanted on the real terminal, and we want init to do its
 874          * setup on its console ie. the pty allocated in lxc_console_create()
 875          * so make sure that that pty is stdin,stdout,stderr.
 876          */
 877         if (lxc_console_set_stdfds(handler->conf->console.slave) < 0)
 878                 goto out_warn_father;
 879
 880         /* If we mounted a temporary proc, then unmount it now */
 881         tmp_proc_unmount(handler->conf);
 882
 883         if (lxc_seccomp_load(handler->conf) != 0)
 884                 goto out_warn_father;
 885
 886         if (run_lxc_hooks(handler->name, "start", handler->conf, handler->lxcpath, NULL)) {
 887                 ERROR("failed to run start hooks for container '%s'.", handler->name);
 888                 goto out_warn_father;
 889         }
 890
 891         /* The clearenv() and putenv() calls have been moved here
 892          * to allow us to use environment variables passed to the various
 893          * hooks, such as the start hook above.  Not all of the
 894          * variables like CONFIG_PATH or ROOTFS are valid in this
 895          * context but others are. */
 896         if (clearenv()) {
 897                 SYSERROR("failed to clear environment");
 898                 /* don't error out though */
 899         }
 900
 901         lxc_list_for_each(iterator, &handler->conf->environment) {
 902                 if (putenv((char *)iterator->elem)) {
 903                         SYSERROR("failed to set environment variable '%s'", (char *)iterator->elem);
 904                         goto out_warn_father;
 905                 }
 906         }
 907
 908         if (putenv("container=lxc")) {
 909                 SYSERROR("failed to set environment variable 'container=lxc'");
 910                 goto out_warn_father;
 911         }
 912
 913         if (handler->conf->pty_names) {
 914                 if (putenv(handler->conf->pty_names)) {
 915                         SYSERROR("failed to set environment variable for container ptys");
 916                         goto out_warn_father;
 917                 }
 918         }
 919
 920         close(handler->sigfd);
 921
 922         if (devnull_fd < 0) {
 923                 devnull_fd = open_devnull();
 924
 925                 if (devnull_fd < 0)
 926                         goto out_warn_father;
 927         }
 928
 929         if (handler->backgrounded && set_stdfds(devnull_fd))
 930                 goto out_warn_father;
 931
 932         if (devnull_fd >= 0) {
 933                 close(devnull_fd);
 934                 devnull_fd = -1;
 935         }
 936
 937         setsid();
 938
 939         /* after this call, we are in error because this
 940          * ops should not return as it execs */
 941         handler->ops->start(handler, handler->data);
 942
 943 out_warn_father:
 944         /* we want the parent to know something went wrong, so we return a special
 945          * error code. */
 946         lxc_sync_wake_parent(handler, LXC_SYNC_ERROR);
 947
 948 out_error:
 949         if (devnull_fd >= 0)
 950                 close(devnull_fd);
 951
 952         return -1;
 953 }
 954
 955 static int save_phys_nics(struct lxc_conf *conf)
 956 {
 957         struct lxc_list *iterator;
 958         int am_root = (getuid() == 0);
 959
 960         if (!am_root)
 961                 return 0;
 962
 963         lxc_list_for_each(iterator, &conf->network) {
 964                 struct lxc_netdev *netdev = iterator->elem;
 965
 966                 if (netdev->type != LXC_NET_PHYS)
 967                         continue;
 968                 conf->saved_nics = realloc(conf->saved_nics,
 969                                 (conf->num_savednics+1)*sizeof(struct saved_nic));
 970                 if (!conf->saved_nics) {
 971                         SYSERROR("failed to allocate memory");
 972                         return -1;
 973                 }
 974                 conf->saved_nics[conf->num_savednics].ifindex = netdev->ifindex;
 975                 conf->saved_nics[conf->num_savednics].orig_name = strdup(netdev->link);
 976                 if (!conf->saved_nics[conf->num_savednics].orig_name) {
 977                         SYSERROR("failed to allocate memory");
 978                         return -1;
 979                 }
 980                 INFO("stored saved_nic #%d idx %d name %s", conf->num_savednics,
 981                         conf->saved_nics[conf->num_savednics].ifindex,
 982                         conf->saved_nics[conf->num_savednics].orig_name);
 983                 conf->num_savednics++;
 984         }
 985
 986         return 0;
 987 }
 988
 989 static int recv_fd(int sock, int *fd)
 990 {
 991         if (lxc_abstract_unix_recv_fd(sock, fd, NULL, 0) < 0) {
 992                 SYSERROR("Error receiving tty fd from child");
 993                 return -1;
 994         }
 995         if (*fd == -1)
 996                 return -1;
 997         return 0;
 998 }
 999
1000 static int recv_ttys_from_child(struct lxc_handler *handler)
1001 {
1002         struct lxc_conf *conf = handler->conf;
1003         int i, sock = handler->ttysock[1];
1004         struct lxc_tty_info *tty_info = &conf->tty_info;
1005
1006         if (!conf->tty)
1007                 return 0;
1008
1009         tty_info->pty_info = malloc(sizeof(*tty_info->pty_info)*conf->tty);
1010         if (!tty_info->pty_info) {
1011                 SYSERROR("failed to allocate pty_info");
1012                 return -1;
1013         }
1014
1015         for (i = 0; i < conf->tty; i++) {
1016                 struct lxc_pty_info *pty_info = &tty_info->pty_info[i];
1017                 pty_info->busy = 0;
1018                 if (recv_fd(sock, &pty_info->slave) < 0 ||
1019                                 recv_fd(sock, &pty_info->master) < 0) {
1020                         ERROR("Error receiving tty info from child");
1021                         return -1;
1022                 }
1023         }
1024         tty_info->nbtty = conf->tty;
1025
1026         return 0;
1027 }
1028
1029 void resolve_clone_flags(struct lxc_handler *handler)
1030 {
1031         handler->clone_flags = CLONE_NEWPID | CLONE_NEWNS;
1032
1033         if (!lxc_list_empty(&handler->conf->id_map)) {
1034                 INFO("Cloning a new user namespace");
1035                 handler->clone_flags |= CLONE_NEWUSER;
1036         }
1037
1038         if (handler->conf->inherit_ns_fd[LXC_NS_NET] == -1) {
1039                 if (!lxc_requests_empty_network(handler))
1040                         handler->clone_flags |= CLONE_NEWNET;
1041         } else {
1042                 INFO("Inheriting a net namespace");
1043         }
1044
1045         if (handler->conf->inherit_ns_fd[LXC_NS_IPC] == -1) {
1046                 handler->clone_flags |= CLONE_NEWIPC;
1047         } else {
1048                 INFO("Inheriting an IPC namespace");
1049         }
1050
1051         if (handler->conf->inherit_ns_fd[LXC_NS_UTS] == -1) {
1052                 handler->clone_flags |= CLONE_NEWUTS;
1053         } else {
1054                 INFO("Inheriting a UTS namespace");
1055         }
1056 }
1057
1058 static int lxc_spawn(struct lxc_handler *handler)
1059 {
1060         int failed_before_rename = 0;
1061         const char *name = handler->name;
1062         char *errmsg = NULL;
1063         bool cgroups_connected = false;
1064         int saved_ns_fd[LXC_NS_MAX];
1065         int preserve_mask = 0, i, flags;
1066         int netpipepair[2], nveths;
1067
1068         netpipe = -1;
1069
1070         for (i = 0; i < LXC_NS_MAX; i++)
1071                 if (handler->conf->inherit_ns_fd[i] != -1)
1072                         preserve_mask |= ns_info[i].clone_flag;
1073
1074         if (lxc_sync_init(handler))
1075                 return -1;
1076
1077         if (socketpair(AF_UNIX, SOCK_DGRAM, 0, handler->ttysock) < 0) {
1078                 lxc_sync_fini(handler);
1079                 return -1;
1080         }
1081
1082         resolve_clone_flags(handler);
1083
1084         if (handler->clone_flags & CLONE_NEWNET) {
1085                 if (!lxc_list_empty(&handler->conf->network)) {
1086
1087                         /* Find gateway addresses from the link device, which is
1088                          * no longer accessible inside the container. Do this
1089                          * before creating network interfaces, since goto
1090                          * out_delete_net does not work before lxc_clone. */
1091                         if (lxc_find_gateway_addresses(handler)) {
1092                                 ERROR("failed to find gateway addresses");
1093                                 lxc_sync_fini(handler);
1094                                 return -1;
1095                         }
1096
1097                         /* that should be done before the clone because we will
1098                          * fill the netdev index and use them in the child
1099                          */
1100                         if (lxc_create_network(handler)) {
1101                                 ERROR("failed to create the network");
1102                                 lxc_sync_fini(handler);
1103                                 return -1;
1104                         }
1105                 }
1106
1107                 if (save_phys_nics(handler->conf)) {
1108                         ERROR("failed to save physical nic info");
1109                         goto out_abort;
1110                 }
1111         }
1112
1113         if (!cgroup_init(handler)) {
1114                 ERROR("failed initializing cgroup support");
1115                 goto out_delete_net;
1116         }
1117
1118         cgroups_connected = true;
1119
1120         if (!cgroup_create(handler)) {
1121                 ERROR("failed creating cgroups");
1122                 goto out_delete_net;
1123         }
1124
1125         /*
1126          * if the rootfs is not a blockdev, prevent the container from
1127          * marking it readonly.
1128          *
1129          * if the container is unprivileged then skip rootfs pinning
1130          */
1131         if (lxc_list_empty(&handler->conf->id_map)) {
1132                 handler->pinfd = pin_rootfs(handler->conf->rootfs.path);
1133                 if (handler->pinfd == -1)
1134                         INFO("failed to pin the container's rootfs");
1135         }
1136
1137         if (!preserve_ns(saved_ns_fd, preserve_mask, getpid(), &errmsg)) {
1138                 SYSERROR("Failed to preserve requested namespaces: %s",
1139                         errmsg ? errmsg : "(Out of memory)");
1140                 free(errmsg);
1141                 goto out_delete_net;
1142         }
1143         if (attach_ns(handler->conf->inherit_ns_fd) < 0)
1144                 goto out_delete_net;
1145
1146         if (am_unpriv() && (nveths = count_veths(&handler->conf->network))) {
1147                 if (pipe(netpipepair) < 0) {
1148                         SYSERROR("Error creating pipe");
1149                         goto out_delete_net;
1150                 }
1151                 /* store netpipe in the global var for do_start's use */
1152                 netpipe = netpipepair[0];
1153         }
1154
1155         /* Create a process in a new set of namespaces */
1156         flags = handler->clone_flags;
1157         if (handler->clone_flags & CLONE_NEWUSER)
1158                 flags &= ~CLONE_NEWNET;
1159         if (cgns_supported()) {
1160                 handler->clone_flags |= CLONE_NEWCGROUP;
1161                 flags |= CLONE_NEWCGROUP;
1162         }
1163         handler->pid = lxc_clone(do_start, handler, flags);
1164         if (handler->pid < 0) {
1165                 SYSERROR("failed to fork into a new namespace");
1166                 goto out_delete_net;
1167         }
1168
1169         if (!preserve_ns(handler->nsfd, handler->clone_flags | preserve_mask, handler->pid, &errmsg)) {
1170                 INFO("Failed to store namespace references for stop hook: %s",
1171                         errmsg ? errmsg : "(Out of memory)");
1172                 free(errmsg);
1173         }
1174
1175         if (attach_ns(saved_ns_fd))
1176                 WARN("failed to restore saved namespaces");
1177
1178         lxc_sync_fini_child(handler);
1179
1180         /* map the container uids - the container became an invalid
1181          * userid the moment it was cloned with CLONE_NEWUSER - this
1182          * call doesn't change anything immediately, but allows the
1183          * container to setuid(0) (0 being mapped to something else on
1184          * the host) later to become a valid uid again */
1185         if (lxc_map_ids(&handler->conf->id_map, handler->pid)) {
1186                 ERROR("failed to set up id mapping");
1187                 goto out_delete_net;
1188         }
1189
1190         if (lxc_sync_wake_child(handler, LXC_SYNC_STARTUP)) {
1191                 failed_before_rename = 1;
1192                 goto out_delete_net;
1193         }
1194
1195         if (lxc_sync_wait_child(handler, LXC_SYNC_CONFIGURE)) {
1196                 failed_before_rename = 1;
1197                 goto out_delete_net;
1198         }
1199
1200         if (!cgroup_create_legacy(handler)) {
1201                 ERROR("failed to setup the legacy cgroups for %s", name);
1202                 goto out_delete_net;
1203         }
1204         if (!cgroup_setup_limits(handler, false)) {
1205                 ERROR("failed to setup the cgroup limits for '%s'", name);
1206                 goto out_delete_net;
1207         }
1208
1209         if (!cgroup_enter(handler))
1210                 goto out_delete_net;
1211
1212         if (!cgroup_chown(handler))
1213                 goto out_delete_net;
1214
1215         if (failed_before_rename)
1216                 goto out_delete_net;
1217
1218         /* Create the network configuration */
1219         if (handler->clone_flags & CLONE_NEWNET) {
1220                 if (lxc_assign_network(handler->lxcpath, handler->name,
1221                                         &handler->conf->network, handler->pid)) {
1222                         ERROR("failed to create the configured network");
1223                         goto out_delete_net;
1224                 }
1225         }
1226
1227         if (netpipe != -1) {
1228                 struct lxc_list *iterator;
1229                 struct lxc_netdev *netdev;
1230
1231                 close(netpipe);
1232                 lxc_list_for_each(iterator, &handler->conf->network) {
1233                         netdev = iterator->elem;
1234                         if (netdev->type != LXC_NET_VETH)
1235                                 continue;
1236                         if (write(netpipepair[1], netdev->name, IFNAMSIZ) != IFNAMSIZ) {
1237                                 ERROR("Error writing veth name to container");
1238                                 goto out_delete_net;
1239                         }
1240                 }
1241                 close(netpipepair[1]);
1242         }
1243
1244         /* Tell the child to continue its initialization.  we'll get
1245          * LXC_SYNC_CGROUP when it is ready for us to setup cgroups
1246          */
1247         if (lxc_sync_barrier_child(handler, LXC_SYNC_POST_CONFIGURE))
1248                 goto out_delete_net;
1249
1250         if (!cgroup_setup_limits(handler, true)) {
1251                 ERROR("failed to setup the devices cgroup for '%s'", name);
1252                 goto out_delete_net;
1253         }
1254
1255         cgroup_disconnect();
1256         cgroups_connected = false;
1257
1258         /* read tty fds allocated by child */
1259         if (recv_ttys_from_child(handler) < 0) {
1260                 ERROR("failed to receive tty info from child");
1261                 goto out_delete_net;
1262         }
1263
1264         /* Tell the child to complete its initialization and wait for
1265          * it to exec or return an error.  (the child will never
1266          * return LXC_SYNC_POST_CGROUP+1.  It will either close the
1267          * sync pipe, causing lxc_sync_barrier_child to return
1268          * success, or return a different value, causing us to error
1269          * out).
1270          */
1271         if (lxc_sync_barrier_child(handler, LXC_SYNC_POST_CGROUP))
1272                 return -1;
1273
1274         if (detect_shared_rootfs())
1275                 umount2(handler->conf->rootfs.mount, MNT_DETACH);
1276
1277         if (handler->ops->post_start(handler, handler->data))
1278                 goto out_abort;
1279
1280         if (lxc_set_state(name, handler, RUNNING)) {
1281                 ERROR("failed to set state to %s",
1282                               lxc_state2str(RUNNING));
1283                 goto out_abort;
1284         }
1285
1286         lxc_sync_fini(handler);
1287
1288         return 0;
1289
1290 out_delete_net:
1291         if (cgroups_connected)
1292                 cgroup_disconnect();
1293         if (handler->clone_flags & CLONE_NEWNET)
1294                 lxc_delete_network(handler);
1295 out_abort:
1296         lxc_abort(name, handler);
1297         lxc_sync_fini(handler);
1298         if (handler->pinfd >= 0) {
1299                 close(handler->pinfd);
1300                 handler->pinfd = -1;
1301         }
1302
1303         return -1;
1304 }
1305
1306 int get_netns_fd(int pid)
1307 {
1308         char path[MAXPATHLEN];
1309         int ret, fd;
1310
1311         ret = snprintf(path, MAXPATHLEN, "/proc/%d/ns/net", pid);
1312         if (ret < 0 || ret >= MAXPATHLEN) {
1313                 WARN("Failed to pin netns file for pid %d", pid);
1314                 return -1;
1315         }
1316
1317         fd = open(path, O_RDONLY);
1318         if (fd < 0) {
1319                 WARN("Failed to pin netns file %s for pid %d: %s",
1320                                 path, pid, strerror(errno));
1321                 return -1;
1322         }
1323         return fd;
1324 }
1325
1326 int __lxc_start(const char *name, struct lxc_conf *conf,
1327                 struct lxc_operations* ops, void *data, const char *lxcpath,
1328                 bool backgrounded)
1329 {
1330         struct lxc_handler *handler;
1331         int err = -1;
1332         int status;
1333         int netnsfd = -1;
1334
1335         handler = lxc_init(name, conf, lxcpath);
1336         if (!handler) {
1337                 ERROR("failed to initialize the container");
1338                 return -1;
1339         }
1340         handler->ops = ops;
1341         handler->data = data;
1342         handler->backgrounded = backgrounded;
1343
1344         if (must_drop_cap_sys_boot(handler->conf)) {
1345                 #if HAVE_SYS_CAPABILITY_H
1346                 DEBUG("Dropping cap_sys_boot");
1347                 #else
1348                 DEBUG("Can't drop cap_sys_boot as capabilities aren't supported");
1349                 #endif
1350         } else {
1351                 DEBUG("Not dropping cap_sys_boot or watching utmp");
1352                 handler->conf->need_utmp_watch = 0;
1353         }
1354
1355         if (!attach_block_device(handler->conf)) {
1356                 ERROR("Failure attaching block device");
1357                 goto out_fini_nonet;
1358         }
1359
1360         if (geteuid() == 0 && !lxc_list_empty(&conf->id_map)) {
1361                 /* if the backing store is a device, mount it here and now */
1362                 if (rootfs_is_blockdev(conf)) {
1363                         if (unshare(CLONE_NEWNS) < 0) {
1364                                 ERROR("Error unsharing mounts");
1365                                 goto out_fini_nonet;
1366                         }
1367                         remount_all_slave();
1368                         if (do_rootfs_setup(conf, name, lxcpath) < 0) {
1369                                 ERROR("Error setting up rootfs mount as root before spawn");
1370                                 goto out_fini_nonet;
1371                         }
1372                         INFO("Set up container rootfs as host root");
1373                 }
1374         }
1375
1376         err = lxc_spawn(handler);
1377         if (err) {
1378                 ERROR("failed to spawn '%s'", name);
1379                 goto out_detach_blockdev;
1380         }
1381
1382         handler->conf->reboot = 0;
1383
1384         netnsfd = get_netns_fd(handler->pid);
1385
1386         err = lxc_poll(name, handler);
1387         if (err) {
1388                 ERROR("mainloop exited with an error");
1389                 if (netnsfd >= 0)
1390                         close(netnsfd);
1391                 goto out_abort;
1392         }
1393
1394         while (waitpid(handler->pid, &status, 0) < 0 && errno == EINTR)
1395                 continue;
1396
1397         /*
1398          * If the child process exited but was not signaled,
1399          * it didn't call reboot.  This should mean it was an
1400          * lxc-execute which simply exited.  In any case, treat
1401          * it as a 'halt'
1402          */
1403         if (WIFSIGNALED(status)) {
1404                 switch(WTERMSIG(status)) {
1405                 case SIGINT: /* halt */
1406                         DEBUG("Container halting");
1407                         break;
1408                 case SIGHUP: /* reboot */
1409                         DEBUG("Container rebooting");
1410                         handler->conf->reboot = 1;
1411                         break;
1412                 case SIGSYS: /* seccomp */
1413                         DEBUG("Container violated its seccomp policy");
1414                         break;
1415                 default:
1416                         DEBUG("unknown exit status for init: %d", WTERMSIG(status));
1417                         break;
1418                 }
1419         }
1420
1421         DEBUG("Pushing physical nics back to host namespace");
1422         lxc_restore_phys_nics_to_netns(netnsfd, handler->conf);
1423
1424         DEBUG("Tearing down virtual network devices used by container");
1425         lxc_delete_network(handler);
1426
1427         if (netnsfd >= 0)
1428                 close(netnsfd);
1429
1430         if (handler->pinfd >= 0) {
1431                 close(handler->pinfd);
1432                 handler->pinfd = -1;
1433         }
1434
1435         lxc_monitor_send_exit_code(name, status, handler->lxcpath);
1436         err =  lxc_error_set_and_log(handler->pid, status);
1437 out_fini:
1438         lxc_delete_network(handler);
1439
1440 out_detach_blockdev:
1441         detach_block_device(handler->conf);
1442
1443 out_fini_nonet:
1444         lxc_fini(name, handler);
1445         return err;
1446
1447 out_abort:
1448         lxc_abort(name, handler);
1449         goto out_fini;
1450 }
1451
1452 struct start_args {
1453         char *const *argv;
1454 };
1455
1456 static int start(struct lxc_handler *handler, void* data)
1457 {
1458         struct start_args *arg = data;
1459
1460         NOTICE("exec'ing '%s'", arg->argv[0]);
1461
1462         execvp(arg->argv[0], arg->argv);
1463         SYSERROR("failed to exec %s", arg->argv[0]);
1464         return 0;
1465 }
1466
1467 static int post_start(struct lxc_handler *handler, void* data)
1468 {
1469         struct start_args *arg = data;
1470
1471         NOTICE("'%s' started with pid '%d'", arg->argv[0], handler->pid);
1472         return 0;
1473 }
1474
1475 static struct lxc_operations start_ops = {
1476         .start = start,
1477         .post_start = post_start
1478 };
1479
1480 int lxc_start(const char *name, char *const argv[], struct lxc_conf *conf,
1481               const char *lxcpath, bool backgrounded)
1482 {
1483         struct start_args start_arg = {
1484                 .argv = argv,
1485         };
1486
1487         conf->need_utmp_watch = 1;
1488         return __lxc_start(name, conf, &start_ops, &start_arg, lxcpath, backgrounded);
1489 }
1490
1491 static void lxc_destroy_container_on_signal(struct lxc_handler *handler,
1492                                             const char *name)
1493 {
1494         char destroy[MAXPATHLEN];
1495         bool bret = true;
1496         int ret = 0;
1497         struct lxc_container *c;
1498         if (handler->conf->rootfs.path && handler->conf->rootfs.mount) {
1499                 bret = do_destroy_container(handler->conf);
1500                 if (!bret) {
1501                         ERROR("Error destroying rootfs for %s", name);
1502                         return;
1503                 }
1504         }
1505         INFO("Destroyed rootfs for %s", name);
1506
1507         ret = snprintf(destroy, MAXPATHLEN, "%s/%s", handler->lxcpath, name);
1508         if (ret < 0 || ret >= MAXPATHLEN) {
1509                 ERROR("Error printing path for %s", name);
1510                 ERROR("Error destroying directory for %s", name);
1511                 return;
1512         }
1513
1514         c = lxc_container_new(name, handler->lxcpath);
1515         if (c) {
1516                 if (container_disk_lock(c)) {
1517                         INFO("Could not update lxc_snapshots file");
1518                         lxc_container_put(c);
1519                 } else {
1520                         mod_all_rdeps(c, false);
1521                         container_disk_unlock(c);
1522                         lxc_container_put(c);
1523                 }
1524         }
1525
1526         if (am_unpriv())
1527                 ret = userns_exec_1(handler->conf, lxc_rmdir_onedev_wrapper, destroy);
1528         else
1529                 ret = lxc_rmdir_onedev(destroy, NULL);
1530
1531         if (ret < 0) {
1532                 ERROR("Error destroying directory for %s", name);
1533                 return;
1534         }
1535         INFO("Destroyed directory for %s", name);
1536 }
1537
1538 static int lxc_rmdir_onedev_wrapper(void *data)
1539 {
1540         char *arg = (char *) data;
1541         return lxc_rmdir_onedev(arg, NULL);
1542 }
1543
1544 static bool do_destroy_container(struct lxc_conf *conf) {
1545         if (am_unpriv()) {
1546                 if (userns_exec_1(conf, bdev_destroy_wrapper, conf) < 0)
1547                         return false;
1548                 return true;
1549         }
1550         return bdev_destroy(conf);
1551 }