src/lxc/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 <sys/param.h>
  34 #include <sys/file.h>
  35 #include <sys/mount.h>
  36 #include <sys/types.h>
  37 #include <sys/prctl.h>
  38 #include <sys/wait.h>
  39
  40 #include <lxc/lxc.h>
  41
  42 LXC_TTY_HANDLER(SIGINT);
  43 LXC_TTY_HANDLER(SIGQUIT);
  44
  45 int lxc_start(const char *name, int argc, char *argv[],
  46               lxc_callback_t prestart, void *data)
  47 {
  48         char init[MAXPATHLEN];
  49         char *val = NULL;
  50         char ttyname[MAXPATHLEN];
  51         int fd, lock, sv[2], sync = 0, err = -1;
  52         pid_t pid;
  53         int clone_flags;
  54
  55         lock = lxc_get_lock(name);
  56         if (!lock) {
  57                 lxc_log_error("'%s' is busy", name);
  58                 return -1;
  59         }
  60
  61         if (lock < 0) {
  62                 lxc_log_error("failed to acquire lock on '%s':%s",
  63                               name, strerror(-lock));
  64                 return -1;
  65         }
  66
  67         /* Begin the set the state to STARTING*/
  68         if (lxc_setstate(name, STARTING)) {
  69                 lxc_log_error("failed to set state %s", lxc_state2str(STARTING));
  70                 goto out;
  71         }
  72
  73         if (readlink("/proc/self/fd/0", ttyname, sizeof(ttyname)) < 0) {
  74                 lxc_log_syserror("failed to read '/proc/self/fd/0'");
  75                 goto out;
  76         }
  77
  78
  79         /* Synchro socketpair */
  80         if (socketpair(AF_LOCAL, SOCK_STREAM, 0, sv)) {
  81                 lxc_log_syserror("failed to create communication socketpair");
  82                 goto out;
  83         }
  84
  85         /* Avoid signals from terminal */
  86         LXC_TTY_ADD_HANDLER(SIGINT);
  87         LXC_TTY_ADD_HANDLER(SIGQUIT);
  88
  89         clone_flags = CLONE_NEWPID|CLONE_NEWIPC|CLONE_NEWNS;
  90         if (conf_has_utsname(name))
  91                 clone_flags |= CLONE_NEWUTS;
  92         if (conf_has_network(name))
  93                 clone_flags |= CLONE_NEWNET;
  94
  95         /* Create a process in a new set of namespaces */
  96         pid = fork_ns(clone_flags);
  97         if (pid < 0) {
  98                 lxc_log_syserror("failed to fork into a new namespace");
  99                 goto err_fork_ns;
 100         }
 101
 102         if (!pid) {
 103
 104                 close(sv[1]);
 105
 106                 /* Be sure we don't inherit this after the exec */
 107                 fcntl(sv[0], F_SETFD, FD_CLOEXEC);
 108
 109                 /* Tell our father he can begin to configure the container */
 110                 if (write(sv[0], &sync, sizeof(sync)) < 0) {
 111                         lxc_log_syserror("failed to write socket");
 112                         goto out_child;
 113                 }
 114
 115                 /* Wait for the father to finish the configuration */
 116                 if (read(sv[0], &sync, sizeof(sync)) < 0) {
 117                         lxc_log_syserror("failed to read socket");
 118                         goto out_child;
 119                 }
 120
 121                 /* Setup the container, ip, names, utsname, ... */
 122                 if (lxc_setup(name)) {
 123                         lxc_log_error("failed to setup the container");
 124                         if (write(sv[0], &sync, sizeof(sync)) < 0)
 125                                 lxc_log_syserror("failed to write the socket");
 126                         goto out_child;
 127                 }
 128
 129                 if (mount(ttyname, "/dev/console", "none", MS_BIND, 0)) {
 130                         lxc_log_syserror("failed to mount '/dev/console'");
 131                         goto out_child;
 132                 }
 133
 134                 /* If a callback has been passed, call it before doing exec */
 135                 if (prestart)
 136                         if (prestart(name, argc, argv, data)) {
 137                                 lxc_log_error("prestart callback has failed");
 138                                 goto out_child;
 139                         }
 140
 141                 execvp(argv[0], argv);
 142                 lxc_log_syserror("failed to exec %s", argv[0]);
 143
 144                 /* If the exec fails, tell that to our father */
 145                 if (write(sv[0], &sync, sizeof(sync)) < 0)
 146                         lxc_log_syserror("failed to write the socket");
 147
 148         out_child:
 149                 exit(1);
 150         }
 151
 152         close(sv[0]);
 153
 154         /* Wait for the child to be ready */
 155         if (read(sv[1], &sync, sizeof(sync)) < 0) {
 156                 lxc_log_syserror("failed to read the socket");
 157                 goto err_pipe_read;
 158         }
 159
 160         if (lxc_link_nsgroup(name, pid))
 161                 lxc_log_warning("cgroupfs not found: cgroup disabled");
 162
 163         /* Create the network configuration */
 164         if (clone_flags & CLONE_NEWNET && conf_create_network(name, pid)) {
 165                 lxc_log_error("failed to create the configured network");
 166                 goto err_create_network;
 167         }
 168
 169         /* Tell the child to continue its initialization */
 170         if (write(sv[1], &sync, sizeof(sync)) < 0) {
 171                 lxc_log_syserror("failed to write the socket");
 172                 goto err_pipe_write;
 173         }
 174
 175         /* Wait for the child to exec or returning an error */
 176         err = read(sv[1], &sync, sizeof(sync));
 177         if (err < 0) {
 178                 lxc_log_error("failed to read the socket");
 179                 goto err_pipe_read2;
 180         }
 181
 182         if (err > 0) {
 183                 lxc_log_error("something went wrong with %d", pid);
 184                 /* TODO : check status etc ... */
 185                 waitpid(pid, NULL, 0);
 186                 goto err_child_failed;
 187         }
 188
 189         asprintf(&val, "%d\n", pid);
 190
 191         snprintf(init, MAXPATHLEN, LXCPATH "/%s/init", name);
 192
 193         fd = open(init, O_WRONLY|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR);
 194         if (fd < 0) {
 195                 lxc_log_syserror("failed to open '%s'", init);
 196                 goto err_write;
 197         }
 198
 199         if (write(fd, val, strlen(val)) < 0) {
 200                 lxc_log_syserror("failed to write the init pid");
 201                 goto err_write;
 202         }
 203
 204         close(fd);
 205
 206         if (lxc_setstate(name, RUNNING)) {
 207                 lxc_log_error("failed to set state to %s",
 208                               lxc_state2str(RUNNING));
 209                 goto err_state_failed;
 210         }
 211
 212 wait_again:
 213         if (waitpid(pid, NULL, 0) < 0) {
 214                 if (errno == EINTR)
 215                         goto wait_again;
 216                 lxc_log_syserror("failed to wait the pid %d", pid);
 217                 goto err_waitpid_failed;
 218         }
 219
 220         if (lxc_setstate(name, STOPPING))
 221                 lxc_log_error("failed to set state %s", lxc_state2str(STOPPING));
 222
 223         if (clone_flags & CLONE_NEWNET && conf_destroy_network(name))
 224                 lxc_log_error("failed to destroy the network");
 225
 226         err = 0;
 227 out:
 228         if (lxc_setstate(name, STOPPED))
 229                 lxc_log_error("failed to set state %s", lxc_state2str(STOPPED));
 230
 231         lxc_unlink_nsgroup(name);
 232         unlink(init);
 233         free(val);
 234         lxc_put_lock(lock);
 235         LXC_TTY_DEL_HANDLER(SIGQUIT);
 236         LXC_TTY_DEL_HANDLER(SIGINT);
 237
 238         return err;
 239
 240 err_write:
 241         close(fd);
 242
 243 err_state_failed:
 244 err_child_failed:
 245 err_pipe_read2:
 246 err_pipe_write:
 247         if (clone_flags & CLONE_NEWNET)
 248                 conf_destroy_network(name);
 249 err_create_network:
 250 err_pipe_read:
 251 err_waitpid_failed:
 252         if (lxc_setstate(name, ABORTING))
 253                 lxc_log_error("failed to set state %s", lxc_state2str(STOPPED));
 254
 255         kill(pid, SIGKILL);
 256 err_fork_ns:
 257         close(sv[0]);
 258         close(sv[1]);
 259         goto out;
 260 }