/
start.c
1644 lines (1356 loc) · 42.3 KB
/
start.c
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/*
* lxc: linux Container library
*
* (C) Copyright IBM Corp. 2007, 2008
*
* Authors:
* Daniel Lezcano <daniel.lezcano at free.fr>
* Serge Hallyn <serge@hallyn.com>
* Christian Brauner <christian.brauner@ubuntu.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#define _GNU_SOURCE
#include "config.h"
#include <alloca.h>
#include <dirent.h>
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/file.h>
#include <sys/mount.h>
#include <sys/param.h>
#include <sys/prctl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/un.h>
#include <sys/wait.h>
#if HAVE_LIBCAP
#include <sys/capability.h>
#endif
#ifndef HAVE_DECL_PR_CAPBSET_DROP
#define PR_CAPBSET_DROP 24
#endif
#ifndef HAVE_DECL_PR_SET_NO_NEW_PRIVS
#define PR_SET_NO_NEW_PRIVS 38
#endif
#ifndef HAVE_DECL_PR_GET_NO_NEW_PRIVS
#define PR_GET_NO_NEW_PRIVS 39
#endif
#include "af_unix.h"
#include "caps.h"
#include "cgroup.h"
#include "commands.h"
#include "commands_utils.h"
#include "conf.h"
#include "confile_utils.h"
#include "console.h"
#include "error.h"
#include "log.h"
#include "lxccontainer.h"
#include "lxclock.h"
#include "lxcseccomp.h"
#include "mainloop.h"
#include "monitor.h"
#include "namespace.h"
#include "network.h"
#include "start.h"
#include "storage.h"
#include "storage_utils.h"
#include "sync.h"
#include "utils.h"
#include "lsm/lsm.h"
lxc_log_define(lxc_start, lxc);
extern void mod_all_rdeps(struct lxc_container *c, bool inc);
static bool do_destroy_container(struct lxc_handler *handler);
static int lxc_rmdir_onedev_wrapper(void *data);
static void lxc_destroy_container_on_signal(struct lxc_handler *handler,
const char *name);
static void print_top_failing_dir(const char *path)
{
size_t len = strlen(path);
char *copy = alloca(len + 1), *p, *e, saved;
strcpy(copy, path);
p = copy;
e = copy + len;
while (p < e) {
while (p < e && *p == '/')
p++;
while (p < e && *p != '/')
p++;
saved = *p;
*p = '\0';
if (access(copy, X_OK)) {
SYSERROR("Could not access %s. Please grant it x "
"access, or add an ACL for the container "
"root.", copy);
return;
}
*p = saved;
}
}
static void close_ns(int ns_fd[LXC_NS_MAX])
{
int i;
for (i = 0; i < LXC_NS_MAX; i++) {
if (ns_fd[i] > -1) {
close(ns_fd[i]);
ns_fd[i] = -1;
}
}
}
/* preserve_ns: open /proc/@pid/ns/@ns for each namespace specified
* in clone_flags.
* Return true on success, false on failure.
*/
static bool preserve_ns(int ns_fd[LXC_NS_MAX], int clone_flags, pid_t pid)
{
int i, ret;
for (i = 0; i < LXC_NS_MAX; i++)
ns_fd[i] = -1;
ret = lxc_preserve_ns(pid, "");
if (ret < 0) {
SYSERROR("Kernel does not support attaching to namespaces.");
return false;
} else {
close(ret);
}
for (i = 0; i < LXC_NS_MAX; i++) {
if ((clone_flags & ns_info[i].clone_flag) == 0)
continue;
ns_fd[i] = lxc_preserve_ns(pid, ns_info[i].proc_name);
if (ns_fd[i] < 0)
goto error;
}
return true;
error:
if (errno == ENOENT)
SYSERROR("Kernel does not support attaching to %s namespaces.", ns_info[i].proc_name);
else
SYSERROR("Failed to open file descriptor for %s namespace: %s.", ns_info[i].proc_name, strerror(errno));
close_ns(ns_fd);
return false;
}
static int attach_ns(const int ns_fd[LXC_NS_MAX]) {
int i;
for (i = 0; i < LXC_NS_MAX; i++) {
if (ns_fd[i] < 0)
continue;
if (setns(ns_fd[i], 0) != 0)
goto error;
}
return 0;
error:
SYSERROR("Failed to attach %s namespace.", ns_info[i].proc_name);
return -1;
}
static int match_fd(int fd)
{
return (fd == 0 || fd == 1 || fd == 2);
}
int lxc_check_inherited(struct lxc_conf *conf, bool closeall,
int *fds_to_ignore, size_t len_fds)
{
struct dirent *direntp;
int fd, fddir;
size_t i;
DIR *dir;
if (conf && conf->close_all_fds)
closeall = true;
restart:
dir = opendir("/proc/self/fd");
if (!dir) {
WARN("Failed to open directory: %s.", strerror(errno));
return -1;
}
fddir = dirfd(dir);
while ((direntp = readdir(dir))) {
if (!direntp)
break;
if (!strcmp(direntp->d_name, "."))
continue;
if (!strcmp(direntp->d_name, ".."))
continue;
if (lxc_safe_int(direntp->d_name, &fd) < 0) {
INFO("Could not parse file descriptor for: %s", direntp->d_name);
continue;
}
for (i = 0; i < len_fds; i++)
if (fds_to_ignore[i] == fd)
break;
if (fd == fddir || fd == lxc_log_fd ||
(i < len_fds && fd == fds_to_ignore[i]))
continue;
if (conf) {
for (i = 0; i < LXC_NS_MAX; i++)
if (conf->inherit_ns_fd[i] == fd)
break;
if (i < LXC_NS_MAX)
continue;
}
if (current_config && fd == current_config->logfd)
continue;
if (match_fd(fd))
continue;
if (closeall) {
close(fd);
closedir(dir);
INFO("Closed inherited fd: %d.", fd);
goto restart;
}
WARN("Inherited fd: %d.", fd);
}
/* Only enable syslog at this point to avoid the above logging function
* to open a new fd and make the check_inherited function enter an
* infinite loop.
*/
lxc_log_enable_syslog();
closedir(dir); /* cannot fail */
return 0;
}
static int setup_signal_fd(sigset_t *oldmask)
{
sigset_t mask;
int fd;
/* Block everything except serious error signals. */
if (sigfillset(&mask) ||
sigdelset(&mask, SIGILL) ||
sigdelset(&mask, SIGSEGV) ||
sigdelset(&mask, SIGBUS) ||
sigdelset(&mask, SIGWINCH) ||
sigprocmask(SIG_BLOCK, &mask, oldmask)) {
SYSERROR("Failed to set signal mask.");
return -1;
}
fd = signalfd(-1, &mask, 0);
if (fd < 0) {
SYSERROR("Failed to create signal file descriptor.");
return -1;
}
if (fcntl(fd, F_SETFD, FD_CLOEXEC)) {
SYSERROR("Failed to set FD_CLOEXEC on the signal file descriptor: %d.", fd);
close(fd);
return -1;
}
DEBUG("Set SIGCHLD handler with file descriptor: %d.", fd);
return fd;
}
static int signal_handler(int fd, uint32_t events, void *data,
struct lxc_epoll_descr *descr)
{
struct signalfd_siginfo siginfo;
siginfo_t info;
int ret;
pid_t *pid = data;
bool init_died = false;
ret = read(fd, &siginfo, sizeof(siginfo));
if (ret < 0) {
ERROR("Failed to read signal info from signal file descriptor: %d.", fd);
return -1;
}
if (ret != sizeof(siginfo)) {
ERROR("Unexpected size for siginfo struct.");
return -1;
}
/* Check whether init is running. */
info.si_pid = 0;
ret = waitid(P_PID, *pid, &info, WEXITED | WNOWAIT | WNOHANG);
if (ret == 0 && info.si_pid == *pid)
init_died = true;
if (siginfo.ssi_signo != SIGCHLD) {
kill(*pid, siginfo.ssi_signo);
INFO("Forwarded signal %d to pid %d.", siginfo.ssi_signo, *pid);
return init_died ? 1 : 0;
}
if (siginfo.ssi_code == CLD_STOPPED) {
INFO("Container init process was stopped.");
return init_died ? 1 : 0;
} else if (siginfo.ssi_code == CLD_CONTINUED) {
INFO("Container init process was continued.");
return init_died ? 1 : 0;
}
/* More robustness, protect ourself from a SIGCHLD sent
* by a process different from the container init.
*/
if (siginfo.ssi_pid != *pid) {
NOTICE("Received SIGCHLD from pid %d instead of container init %d.", siginfo.ssi_pid, *pid);
return init_died ? 1 : 0;
}
DEBUG("Container init process %d exited.", *pid);
return 1;
}
static int lxc_serve_state_clients(const char *name,
struct lxc_handler *handler,
lxc_state_t state)
{
ssize_t ret;
struct lxc_list *cur, *next;
struct state_client *client;
struct lxc_msg msg = {.type = lxc_msg_state, .value = state};
process_lock();
/* Only set state under process lock held so that we don't cause
* lxc_cmd_add_state_client() to miss a state.
*/
handler->state = state;
TRACE("set container state to %s", lxc_state2str(state));
if (lxc_list_empty(&handler->state_clients)) {
TRACE("no state clients registered");
process_unlock();
lxc_monitor_send_state(name, state, handler->lxcpath);
return 0;
}
strncpy(msg.name, name, sizeof(msg.name));
msg.name[sizeof(msg.name) - 1] = 0;
lxc_list_for_each_safe(cur, &handler->state_clients, next) {
client = cur->elem;
if (!client->states[state]) {
TRACE("state %s not registered for state client %d",
lxc_state2str(state), client->clientfd);
continue;
}
TRACE("sending state %s to state client %d",
lxc_state2str(state), client->clientfd);
again:
ret = send(client->clientfd, &msg, sizeof(msg), 0);
if (ret <= 0) {
if (errno == EINTR) {
TRACE("Caught EINTR; retrying");
goto again;
}
ERROR("failed to send message to client");
}
/* kick client from list */
close(client->clientfd);
lxc_list_del(cur);
free(cur->elem);
free(cur);
}
process_unlock();
return 0;
}
static int lxc_serve_state_socket_pair(const char *name,
struct lxc_handler *handler,
lxc_state_t state)
{
ssize_t ret;
if (!handler->backgrounded ||
handler->state_socket_pair[1] < 0 ||
state == STARTING)
return 0;
/* Close read end of the socket pair. */
close(handler->state_socket_pair[0]);
handler->state_socket_pair[0] = -1;
again:
ret = lxc_abstract_unix_send_credential(handler->state_socket_pair[1],
&(int){state}, sizeof(int));
if (ret != sizeof(int)) {
if (errno == EINTR)
goto again;
SYSERROR("Failed to send state to %d",
handler->state_socket_pair[1]);
return -1;
}
TRACE("Sent container state \"%s\" to %d", lxc_state2str(state),
handler->state_socket_pair[1]);
/* Close write end of the socket pair. */
close(handler->state_socket_pair[1]);
handler->state_socket_pair[1] = -1;
return 0;
}
int lxc_set_state(const char *name, struct lxc_handler *handler,
lxc_state_t state)
{
int ret;
ret = lxc_serve_state_socket_pair(name, handler, state);
if (ret < 0) {
ERROR("Failed to synchronize via anonymous pair of unix sockets");
return -1;
}
ret = lxc_serve_state_clients(name, handler, state);
if (ret < 0)
return -1;
/* This function will try to connect to the legacy lxc-monitord state
* server and only exists for backwards compatibility.
*/
lxc_monitor_send_state(name, state, handler->lxcpath);
return 0;
}
int lxc_poll(const char *name, struct lxc_handler *handler)
{
int sigfd = handler->sigfd;
int pid = handler->pid;
struct lxc_epoll_descr descr;
if (lxc_mainloop_open(&descr)) {
ERROR("Failed to create LXC mainloop.");
goto out_sigfd;
}
if (lxc_mainloop_add_handler(&descr, sigfd, signal_handler, &pid)) {
ERROR("Failed to add signal handler with file descriptor %d to LXC mainloop.", sigfd);
goto out_mainloop_open;
}
if (lxc_console_mainloop_add(&descr, handler->conf)) {
ERROR("Failed to add console handler to LXC mainloop.");
goto out_mainloop_open;
}
if (lxc_cmd_mainloop_add(name, &descr, handler)) {
ERROR("Failed to add command handler to LXC mainloop.");
goto out_mainloop_open;
}
TRACE("lxc mainloop is ready");
return lxc_mainloop(&descr, -1);
out_mainloop_open:
lxc_mainloop_close(&descr);
out_sigfd:
close(sigfd);
return -1;
}
void lxc_free_handler(struct lxc_handler *handler)
{
if (handler->conf && handler->conf->maincmd_fd)
close(handler->conf->maincmd_fd);
if (handler->state_socket_pair[0] >= 0)
close(handler->state_socket_pair[0]);
if (handler->state_socket_pair[1] >= 0)
close(handler->state_socket_pair[1]);
if (handler->name)
free(handler->name);
handler->conf = NULL;
free(handler);
}
struct lxc_handler *lxc_init_handler(const char *name, struct lxc_conf *conf,
const char *lxcpath, bool daemonize)
{
int i, ret;
struct lxc_handler *handler;
handler = malloc(sizeof(*handler));
if (!handler) {
ERROR("failed to allocate memory");
return NULL;
}
memset(handler, 0, sizeof(*handler));
/* Note that am_unpriv() checks the effective uid. We probably don't
* care if we are real root only if we are running as root so this
* should be fine.
*/
handler->am_root = !am_unpriv();
handler->data_sock[0] = handler->data_sock[1] = -1;
handler->conf = conf;
handler->lxcpath = lxcpath;
handler->pinfd = -1;
handler->state_socket_pair[0] = handler->state_socket_pair[1] = -1;
lxc_list_init(&handler->state_clients);
for (i = 0; i < LXC_NS_MAX; i++)
handler->nsfd[i] = -1;
handler->name = strdup(name);
if (!handler->name) {
ERROR("failed to allocate memory");
goto on_error;
}
if (daemonize && !handler->conf->reboot) {
/* Create socketpair() to synchronize on daemonized startup.
* When the container reboots we don't need to synchronize again
* currently so don't open another socketpair().
*/
ret = socketpair(AF_UNIX, SOCK_STREAM | SOCK_CLOEXEC, 0,
handler->state_socket_pair);
if (ret < 0) {
ERROR("Failed to create anonymous pair of unix sockets");
goto on_error;
}
TRACE("Created anonymous pair {%d,%d} of unix sockets",
handler->state_socket_pair[0],
handler->state_socket_pair[1]);
}
if (lxc_cmd_init(name, handler, lxcpath)) {
ERROR("failed to set up command socket");
goto on_error;
}
TRACE("unix domain socket %d for command server is ready",
handler->conf->maincmd_fd);
return handler;
on_error:
lxc_free_handler(handler);
return NULL;
}
int lxc_init(const char *name, struct lxc_handler *handler)
{
struct lxc_conf *conf = handler->conf;
lsm_init();
TRACE("initialized LSM");
if (lxc_read_seccomp_config(conf) != 0) {
ERROR("Failed loading seccomp policy.");
goto out_close_maincmd_fd;
}
TRACE("read seccomp policy");
/* Begin by setting the state to STARTING. */
if (lxc_set_state(name, handler, STARTING)) {
ERROR("Failed to set state for container \"%s\" to \"%s\".", name, lxc_state2str(STARTING));
goto out_close_maincmd_fd;
}
TRACE("set container state to \"STARTING\"");
/* Start of environment variable setup for hooks. */
if (name && setenv("LXC_NAME", name, 1))
SYSERROR("Failed to set environment variable: LXC_NAME=%s.", name);
if (conf->rcfile && setenv("LXC_CONFIG_FILE", conf->rcfile, 1))
SYSERROR("Failed to set environment variable: LXC_CONFIG_FILE=%s.", conf->rcfile);
if (conf->rootfs.mount && setenv("LXC_ROOTFS_MOUNT", conf->rootfs.mount, 1))
SYSERROR("Failed to set environment variable: LXC_ROOTFS_MOUNT=%s.", conf->rootfs.mount);
if (conf->rootfs.path && setenv("LXC_ROOTFS_PATH", conf->rootfs.path, 1))
SYSERROR("Failed to set environment variable: LXC_ROOTFS_PATH=%s.", conf->rootfs.path);
if (conf->console.path && setenv("LXC_CONSOLE", conf->console.path, 1))
SYSERROR("Failed to set environment variable: LXC_CONSOLE=%s.", conf->console.path);
if (conf->console.log_path && setenv("LXC_CONSOLE_LOGPATH", conf->console.log_path, 1))
SYSERROR("Failed to set environment variable: LXC_CONSOLE_LOGPATH=%s.", conf->console.log_path);
if (setenv("LXC_CGNS_AWARE", "1", 1))
SYSERROR("Failed to set environment variable LXC_CGNS_AWARE=1.");
if (setenv("LXC_LOG_LEVEL", lxc_log_priority_to_string(handler->conf->loglevel), 1))
SYSERROR("Failed to set environment variable LXC_CGNS_AWARE=1.");
/* End of environment variable setup for hooks. */
TRACE("set environment variables");
if (run_lxc_hooks(name, "pre-start", conf, handler->lxcpath, NULL)) {
ERROR("Failed to run lxc.hook.pre-start for container \"%s\".", name);
goto out_aborting;
}
TRACE("ran pre-start hooks");
/* The signal fd has to be created before forking otherwise if the child
* process exits before we setup the signal fd, the event will be lost
* and the command will be stuck.
*/
handler->sigfd = setup_signal_fd(&handler->oldmask);
if (handler->sigfd < 0) {
ERROR("Failed to setup SIGCHLD fd handler.");
goto out_delete_tty;
}
TRACE("set up signal fd");
/* Do this after setting up signals since it might unblock SIGWINCH. */
if (lxc_console_create(conf)) {
ERROR("Failed to create console for container \"%s\".", name);
goto out_restore_sigmask;
}
TRACE("created console");
if (lxc_ttys_shift_ids(conf) < 0) {
ERROR("Failed to shift tty into container.");
goto out_restore_sigmask;
}
TRACE("shifted tty ids");
INFO("container \"%s\" is initialized", name);
return 0;
out_restore_sigmask:
sigprocmask(SIG_SETMASK, &handler->oldmask, NULL);
out_delete_tty:
lxc_delete_tty(&conf->tty_info);
out_aborting:
lxc_set_state(name, handler, ABORTING);
out_close_maincmd_fd:
close(conf->maincmd_fd);
conf->maincmd_fd = -1;
return -1;
}
void lxc_fini(const char *name, struct lxc_handler *handler)
{
int i, rc;
struct lxc_list *cur, *next;
pid_t self = getpid();
char *namespaces[LXC_NS_MAX + 1];
size_t namespace_count = 0;
/* The STOPPING state is there for future cleanup code which can take
* awhile.
*/
lxc_set_state(name, handler, STOPPING);
for (i = 0; i < LXC_NS_MAX; i++) {
if (handler->nsfd[i] != -1) {
rc = asprintf(&namespaces[namespace_count], "%s:/proc/%d/fd/%d",
ns_info[i].proc_name, self, handler->nsfd[i]);
if (rc == -1) {
SYSERROR("Failed to allocate memory.");
break;
}
++namespace_count;
}
}
namespaces[namespace_count] = NULL;
if (handler->conf->reboot && setenv("LXC_TARGET", "reboot", 1))
SYSERROR("Failed to set environment variable: LXC_TARGET=reboot.");
if (!handler->conf->reboot && setenv("LXC_TARGET", "stop", 1))
SYSERROR("Failed to set environment variable: LXC_TARGET=stop.");
if (run_lxc_hooks(name, "stop", handler->conf, handler->lxcpath, namespaces))
ERROR("Failed to run lxc.hook.stop for container \"%s\".", name);
while (namespace_count--)
free(namespaces[namespace_count]);
for (i = 0; i < LXC_NS_MAX; i++) {
if (handler->nsfd[i] != -1) {
close(handler->nsfd[i]);
handler->nsfd[i] = -1;
}
}
if (handler->netnsfd >= 0) {
close(handler->netnsfd);
handler->netnsfd = -1;
}
cgroup_destroy(handler);
lxc_set_state(name, handler, STOPPED);
/* close command socket */
close(handler->conf->maincmd_fd);
handler->conf->maincmd_fd = -1;
if (run_lxc_hooks(name, "post-stop", handler->conf, handler->lxcpath, NULL)) {
ERROR("Failed to run lxc.hook.post-stop for container \"%s\".", name);
if (handler->conf->reboot) {
WARN("Container will be stopped instead of rebooted.");
handler->conf->reboot = 0;
if (setenv("LXC_TARGET", "stop", 1))
WARN("Failed to set environment variable: LXC_TARGET=stop.");
}
}
/* Reset mask set by setup_signal_fd. */
if (sigprocmask(SIG_SETMASK, &handler->oldmask, NULL))
WARN("Failed to restore signal mask.");
lxc_console_delete(&handler->conf->console);
lxc_delete_tty(&handler->conf->tty_info);
/* The command socket is now closed, no more state clients can register
* themselves from now on. So free the list of state clients.
*/
lxc_list_for_each_safe(cur, &handler->state_clients, next) {
struct state_client *client = cur->elem;
/* close state client socket */
close(client->clientfd);
lxc_list_del(cur);
free(cur->elem);
free(cur);
}
if (handler->data_sock[0] != -1) {
close(handler->data_sock[0]);
close(handler->data_sock[1]);
}
if (handler->conf->ephemeral == 1 && handler->conf->reboot != 1)
lxc_destroy_container_on_signal(handler, name);
free(handler->name);
free(handler);
}
void lxc_abort(const char *name, struct lxc_handler *handler)
{
int ret, status;
lxc_set_state(name, handler, ABORTING);
if (handler->pid > 0)
kill(handler->pid, SIGKILL);
while ((ret = waitpid(-1, &status, 0)) > 0) {
;
}
}
static int do_start(void *data)
{
struct lxc_list *iterator;
struct lxc_handler *handler = data;
int devnull_fd = -1, ret;
char path[PATH_MAX];
if (sigprocmask(SIG_SETMASK, &handler->oldmask, NULL)) {
SYSERROR("Failed to set signal mask.");
return -1;
}
/* This prctl must be before the synchro, so if the parent dies before
* we set the parent death signal, we will detect its death with the
* synchro right after, otherwise we have a window where the parent can
* exit before we set the pdeath signal leading to a unsupervized
* container.
*/
if (prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0)) {
SYSERROR("Failed to set PR_SET_PDEATHSIG to SIGKILL.");
return -1;
}
lxc_sync_fini_parent(handler);
/* Don't leak the pinfd to the container. */
if (handler->pinfd >= 0) {
close(handler->pinfd);
}
if (lxc_sync_wait_parent(handler, LXC_SYNC_STARTUP))
return -1;
/* Unshare CLONE_NEWNET after CLONE_NEWUSER. See
* https://github.com/lxc/lxd/issues/1978.
*/
if ((handler->clone_flags & (CLONE_NEWNET | CLONE_NEWUSER)) ==
(CLONE_NEWNET | CLONE_NEWUSER)) {
ret = unshare(CLONE_NEWNET);
if (ret < 0) {
SYSERROR("Failed to unshare CLONE_NEWNET.");
goto out_warn_father;
}
INFO("Unshared CLONE_NEWNET.");
}
/* Tell the parent task it can begin to configure the container and wait
* for it to finish.
*/
if (lxc_sync_barrier_parent(handler, LXC_SYNC_CONFIGURE))
return -1;
if (lxc_network_recv_veth_names_from_parent(handler) < 0) {
ERROR("Failed to receive veth names from parent");
goto out_warn_father;
}
/* If we are in a new user namespace, become root there to have
* privilege over our namespace.
*/
if (!lxc_list_empty(&handler->conf->id_map)) {
if (lxc_switch_uid_gid(0, 0) < 0)
goto out_warn_father;
/* Drop groups only after we switched to a valid gid in the new
* user namespace.
*/
if (lxc_setgroups(0, NULL) < 0)
goto out_warn_father;
}
if (access(handler->lxcpath, X_OK)) {
print_top_failing_dir(handler->lxcpath);
goto out_warn_father;
}
ret = snprintf(path, sizeof(path), "%s/dev/null", handler->conf->rootfs.mount);
if (ret < 0 || ret >= sizeof(path))
goto out_warn_father;
/* In order to checkpoint restore, we need to have everything in the
* same mount namespace. However, some containers may not have a
* reasonable /dev (in particular, they may not have /dev/null), so we
* can't set init's std fds to /dev/null by opening it from inside the
* container.
*
* If that's the case, fall back to using the host's /dev/null. This
* means that migration won't work, but at least we won't spew output
* where it isn't wanted.
*/
if (handler->backgrounded && !handler->conf->autodev && access(path, F_OK) < 0) {
devnull_fd = open_devnull();
if (devnull_fd < 0)
goto out_warn_father;
WARN("Using /dev/null from the host for container init's "
"standard file descriptors. Migration will not work.");
}
/* Ask father to setup cgroups and wait for him to finish. */
if (lxc_sync_barrier_parent(handler, LXC_SYNC_CGROUP))
goto out_error;
/* Unshare cgroup namespace after we have setup our cgroups. If we do it
* earlier we end up with a wrong view of /proc/self/cgroup. For
* example, assume we unshare(CLONE_NEWCGROUP) first, and then create
* the cgroup for the container, say /sys/fs/cgroup/cpuset/lxc/c, then
* /proc/self/cgroup would show us:
*
* 8:cpuset:/lxc/c
*
* whereas it should actually show
*
* 8:cpuset:/
*/
if (cgns_supported()) {
if (unshare(CLONE_NEWCGROUP) < 0) {
INFO("Failed to unshare CLONE_NEWCGROUP.");
goto out_warn_father;
}
INFO("Unshared CLONE_NEWCGROUP.");
}
/* Add the requested environment variables to the current environment to
* allow them to be used by the various hooks, such as the start hook
* above.
*/
lxc_list_for_each(iterator, &handler->conf->environment) {
if (putenv((char *)iterator->elem)) {
SYSERROR("Failed to set environment variable: %s.", (char *)iterator->elem);
goto out_warn_father;
}
}
/* Setup the container, ip, names, utsname, ... */
ret = lxc_setup(handler);
close(handler->data_sock[0]);
close(handler->data_sock[1]);
if (ret < 0) {
ERROR("Failed to setup container \"%s\".", handler->name);
goto out_warn_father;
}
/* Set the label to change to when we exec(2) the container's init. */
if (lsm_process_label_set(NULL, handler->conf, 1, 1) < 0)
goto out_warn_father;
/* Set PR_SET_NO_NEW_PRIVS after we changed the lsm label. If we do it
* before we aren't allowed anymore.
*/
if (handler->conf->no_new_privs) {
if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) < 0) {
SYSERROR("Could not set PR_SET_NO_NEW_PRIVS to block execve() gainable privileges.");
goto out_warn_father;
}
DEBUG("Set PR_SET_NO_NEW_PRIVS to block execve() gainable privileges.");
}
/* Some init's such as busybox will set sane tty settings on stdin,
* stdout, stderr which it thinks is the console. We already set them
* the way we wanted on the real terminal, and we want init to do its
* setup on its console ie. the pty allocated in lxc_console_create() so
* make sure that that pty is stdin,stdout,stderr.
*/
if (handler->conf->console.slave >= 0)
if (set_stdfds(handler->conf->console.slave) < 0) {
ERROR("Failed to redirect std{in,out,err} to pty file "
"descriptor %d",
handler->conf->console.slave);
goto out_warn_father;
}
/* If we mounted a temporary proc, then unmount it now. */
tmp_proc_unmount(handler->conf);
if (lxc_seccomp_load(handler->conf) != 0)
goto out_warn_father;
if (run_lxc_hooks(handler->name, "start", handler->conf, handler->lxcpath, NULL)) {
ERROR("Failed to run lxc.hook.start for container \"%s\".", handler->name);
goto out_warn_father;
}
close(handler->sigfd);
if (devnull_fd < 0) {
devnull_fd = open_devnull();
if (devnull_fd < 0)
goto out_warn_father;
}
if (handler->conf->console.slave < 0 && handler->backgrounded)
if (set_stdfds(devnull_fd) < 0) {
ERROR("Failed to redirect std{in,out,err} to "
"\"/dev/null\"");