src/liblxc/start.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <dlezcano at fr.ibm.com>
   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., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  22  */
  23
  24 #define _GNU_SOURCE
  25 #include <stdio.h>
  26 #undef _GNU_SOURCE
  27 #include <string.h>
  28 #include <stdlib.h>
  29 #include <dirent.h>
  30 #include <errno.h>
  31 #include <unistd.h>
  32 #include <signal.h>
  33 #include <mntent.h>
  34 #include <sys/param.h>
  35 #include <sys/file.h>
  36 #include <sys/types.h>
  37 #include <sys/stat.h>
  38 #include <sys/prctl.h>
  39 #include <sys/wait.h>
  40 #include <netinet/in.h>
  41 #include <net/if.h>
  42
  43 #include <lxc.h>
  44
  45 LXC_TTY_HANDLER(SIGINT);
  46 LXC_TTY_HANDLER(SIGQUIT);
  47
  48 int lxc_start(const char *name, int argc, char *argv[],
  49               lxc_callback_t prestart, void *data)
  50 {
  51         char *init = NULL, *val = NULL;
  52         int fd, lock, sv[2], sync = 0, err = -1;
  53         pid_t pid;
  54         int clone_flags;
  55
  56         lock = lxc_get_lock(name);
  57         if (!lock) {
  58                 lxc_log_error("'%s' is busy", name);
  59                 return -1;
  60         }
  61
  62         if (lock < 0) {
  63                 lxc_log_error("failed to acquire lock on '%s':%s",
  64                               name, strerror(-lock));
  65                 return -1;
  66         }
  67
  68         fcntl(lock, F_SETFD, FD_CLOEXEC);
  69
  70         /* Begin the set the state to STARTING*/
  71         if (lxc_setstate(name, STARTING)) {
  72                 lxc_log_error("failed to set state %s", lxc_state2str(STARTING));
  73                 goto out;
  74         }
  75
  76         /* Synchro socketpair */
  77         if (socketpair(AF_LOCAL, SOCK_STREAM, 0, sv)) {
  78                 lxc_log_syserror("failed to create communication socketpair");
  79                 goto err;
  80         }
  81
  82         /* Avoid signals from terminal */
  83         LXC_TTY_ADD_HANDLER(SIGINT);
  84         LXC_TTY_ADD_HANDLER(SIGQUIT);
  85
  86         clone_flags = CLONE_NEWPID|CLONE_NEWIPC;
  87         if (conf_has_fstab(name))
  88                 clone_flags |= CLONE_NEWNS;
  89         if (conf_has_utsname(name))
  90                 clone_flags |= CLONE_NEWUTS;
  91         if (conf_has_network(name))
  92                 clone_flags |= CLONE_NEWNET;
  93
  94         /* Create a process in a new set of namespaces */
  95         pid = fork_ns(clone_flags);
  96         if (pid < 0) {
  97                 lxc_log_syserror("failed to fork into a new namespace");
  98                 goto err_fork_ns;
  99         }
 100
 101         if (!pid) {
 102
 103                 close(sv[1]);
 104
 105                 /* Be sure we don't inherit this after the exec */
 106                 fcntl(sv[0], F_SETFD, FD_CLOEXEC);
 107
 108                 /* Tell our father he can begin to configure the container */
 109                 if (write(sv[0], &sync, sizeof(sync)) < 0) {
 110                         lxc_log_syserror("failed to write socket");
 111                         return 1;
 112                 }
 113
 114                 /* Wait for the father to finish the configuration */
 115                 if (read(sv[0], &sync, sizeof(sync)) < 0) {
 116                         lxc_log_syserror("failed to read socket");
 117                         return 1;
 118                 }
 119
 120                 /* Setup the container, ip, names, utsname, ... */
 121                 if (lxc_setup(name)) {
 122                         lxc_log_error("failed to setup the container");
 123                         if (write(sv[0], &sync, sizeof(sync)) < 0)
 124                                 lxc_log_syserror("failed to write the socket");
 125                         return -1;
 126                 }
 127
 128                 /* If a callback has been passed, call it before doing exec */
 129                 if (prestart)
 130                         if (prestart(name, argc, argv, data)) {
 131                                 lxc_log_error("prestart callback has failed");
 132                                 return -1;
 133                         }
 134
 135                 execvp(argv[0], argv);
 136                 lxc_log_syserror("failed to exec %s", argv[0]);
 137
 138                 /* If the exec fails, tell that to our father */
 139                 if (write(sv[0], &sync, sizeof(sync)) < 0)
 140                         lxc_log_syserror("failed to write the socket");
 141
 142                 return 1;
 143         }
 144
 145         close(sv[0]);
 146
 147         /* Wait for the child to be ready */
 148         if (read(sv[1], &sync, sizeof(sync)) < 0) {
 149                 lxc_log_syserror("failed to read the socket");
 150                 goto err_pipe_read;
 151         }
 152
 153         /* Create the network configuration */
 154         if (clone_flags & CLONE_NEWNET && conf_create_network(name, pid)) {
 155                 lxc_log_error("failed to create the configured network");
 156                 goto err_create_network;
 157         }
 158
 159         /* Tell the child to continue its initialization */
 160         if (write(sv[1], &sync, sizeof(sync)) < 0) {
 161                 lxc_log_syserror("failed to write the socket");
 162                 goto err_pipe_write;
 163         }
 164
 165         /* Wait for the child to exec or returning an error */
 166         err = read(sv[1], &sync, sizeof(sync));
 167         if (err < 0) {
 168                 lxc_log_error("failed to read the socket");
 169                 goto err_pipe_read2;
 170         }
 171
 172         if (err > 0) {
 173                 lxc_log_error("something went wrong with %d", pid);
 174                 /* TODO : check status etc ... */
 175                 waitpid(pid, NULL, 0);
 176                 goto err_child_failed;
 177         }
 178
 179         asprintf(&val, "%d\n", pid);
 180         asprintf(&init, LXCPATH "/%s/init", name);
 181         fd = open(init, O_WRONLY|O_CREAT, S_IRUSR|S_IWUSR);
 182         if (fd < 0) {
 183                 lxc_log_syserror("failed to open '%s'", init);
 184                 goto err_write;
 185         }
 186
 187         if (write(fd, val, strlen(val)) < 0) {
 188                 lxc_log_syserror("failed to write the init pid");
 189                 goto err_write;
 190         }
 191
 192         close(fd);
 193
 194         if (lxc_link_nsgroup(name, pid))
 195                 lxc_log_warning("cgroupfs not found: cgroup disabled");
 196
 197         if (lxc_setstate(name, RUNNING)) {
 198                 lxc_log_error("failed to set state to %s", lxc_state2str(RUNNING));
 199                 goto err_state_failed;
 200         }
 201
 202 wait_again:
 203         if (waitpid(pid, NULL, 0) < 0) {
 204                 if (errno == EINTR)
 205                         goto wait_again;
 206                 lxc_log_syserror("failed to wait the pid %d", pid);
 207                 goto err_waitpid_failed;
 208         }
 209
 210         if (lxc_setstate(name, STOPPING))
 211                 lxc_log_error("failed to set state %s", lxc_state2str(STOPPING));
 212
 213         if (clone_flags & CLONE_NEWNET && conf_destroy_network(name))
 214                 lxc_log_error("failed to destroy the network");
 215
 216         err = 0;
 217 out:
 218         if (lxc_setstate(name, STOPPED))
 219                 lxc_log_error("failed to set state %s", lxc_state2str(STOPPED));
 220
 221         lxc_unlink_nsgroup(name);
 222         unlink(init);
 223         free(init);
 224         free(val);
 225         lxc_put_lock(lock);
 226
 227         return err;
 228
 229 err_write:
 230         close(fd);
 231
 232 err_state_failed:
 233 err_child_failed:
 234 err_pipe_read2:
 235 err_pipe_write:
 236         if (clone_flags & CLONE_NEWNET)
 237                 conf_destroy_network(name);
 238 err_create_network:
 239 err_pipe_read:
 240 err_waitpid_failed:
 241         if (lxc_setstate(name, ABORTING))
 242                 lxc_log_error("failed to set state %s", lxc_state2str(STOPPED));
 243
 244         kill(pid, SIGKILL);
 245 err_fork_ns:
 246         LXC_TTY_DEL_HANDLER(SIGQUIT);
 247         LXC_TTY_DEL_HANDLER(SIGINT);
 248         close(sv[0]);
 249         close(sv[1]);
 250 err:
 251         goto out;
 252 }