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/capability.h>
  39 #include <sys/wait.h>
  40
  41 #include "error.h"
  42
  43 #include <lxc/lxc.h>
  44
  45 LXC_TTY_HANDLER(SIGINT);
  46 LXC_TTY_HANDLER(SIGQUIT);
  47
  48 int lxc_start(const char *name, char *argv[])
  49 {
  50         char init[MAXPATHLEN];
  51         char *val = NULL;
  52         int fd, lock, sv[2], sync = 0, err = -LXC_ERROR_INTERNAL;
  53         pid_t pid;
  54         int clone_flags;
  55
  56         lock = lxc_get_lock(name);
  57         if (lock < 0) {
  58                 if (lock == -EWOULDBLOCK)
  59                         return -LXC_ERROR_BUSY;
  60                 if (lock == -ENOENT)
  61                         return -LXC_ERROR_NOT_FOUND;
  62                 return -LXC_ERROR_LOCK;
  63         }
  64
  65         /* Begin the set the state to STARTING*/
  66         if (lxc_setstate(name, STARTING)) {
  67                 lxc_log_error("failed to set state '%s'",
  68                               lxc_state2str(STARTING));
  69                 goto out;
  70         }
  71
  72         /* Synchro socketpair */
  73         if (socketpair(AF_LOCAL, SOCK_STREAM, 0, sv)) {
  74                 lxc_log_syserror("failed to create communication socketpair");
  75                 goto out;
  76         }
  77
  78         /* Avoid signals from terminal */
  79         LXC_TTY_ADD_HANDLER(SIGINT);
  80         LXC_TTY_ADD_HANDLER(SIGQUIT);
  81
  82         clone_flags = CLONE_NEWPID|CLONE_NEWIPC|CLONE_NEWNS;
  83         if (conf_has_utsname(name))
  84                 clone_flags |= CLONE_NEWUTS;
  85         if (conf_has_network(name))
  86                 clone_flags |= CLONE_NEWNET;
  87
  88         /* Create a process in a new set of namespaces */
  89         pid = fork_ns(clone_flags);
  90         if (pid < 0) {
  91                 lxc_log_syserror("failed to fork into a new namespace");
  92                 goto err_fork_ns;
  93         }
  94
  95         if (!pid) {
  96
  97                 close(sv[1]);
  98
  99                 /* Be sure we don't inherit this after the exec */
 100                 fcntl(sv[0], F_SETFD, FD_CLOEXEC);
 101
 102                 /* Tell our father he can begin to configure the container */
 103                 if (write(sv[0], &sync, sizeof(sync)) < 0) {
 104                         lxc_log_syserror("failed to write socket");
 105                         goto out_child;
 106                 }
 107
 108                 /* Wait for the father to finish the configuration */
 109                 if (read(sv[0], &sync, sizeof(sync)) < 0) {
 110                         lxc_log_syserror("failed to read socket");
 111                         goto out_child;
 112                 }
 113
 114                 /* Setup the container, ip, names, utsname, ... */
 115                 err = lxc_setup(name);
 116                 if (err) {
 117                         lxc_log_error("failed to setup the container");
 118                         if (write(sv[0], &err, sizeof(err)) < 0)
 119                                 lxc_log_syserror("failed to write the socket");
 120                         goto out_child;
 121                 }
 122
 123                 if (prctl(PR_CAPBSET_DROP, CAP_SYS_BOOT, 0, 0, 0)) {
 124                         lxc_log_syserror("failed to remove CAP_SYS_BOOT capability");
 125                         goto out_child;
 126                 }
 127
 128                 execvp(argv[0], argv);
 129                 lxc_log_syserror("failed to exec %s", argv[0]);
 130
 131                 /* If the exec fails, tell that to our father */
 132                 if (write(sv[0], &err, sizeof(err)) < 0)
 133                         lxc_log_syserror("failed to write the socket");
 134
 135         out_child:
 136                 exit(err);
 137         }
 138
 139         close(sv[0]);
 140
 141         /* Wait for the child to be ready */
 142         if (read(sv[1], &sync, sizeof(sync)) < 0) {
 143                 lxc_log_syserror("failed to read the socket");
 144                 goto err_pipe_read;
 145         }
 146
 147         if (lxc_link_nsgroup(name, pid))
 148                 lxc_log_warning("cgroupfs not found: cgroup disabled");
 149
 150         /* Create the network configuration */
 151         if (clone_flags & CLONE_NEWNET && conf_create_network(name, pid)) {
 152                 lxc_log_error("failed to create the configured network");
 153                 goto err_create_network;
 154         }
 155
 156         /* Tell the child to continue its initialization */
 157         if (write(sv[1], &sync, sizeof(sync)) < 0) {
 158                 lxc_log_syserror("failed to write the socket");
 159                 goto err_pipe_write;
 160         }
 161
 162         /* Wait for the child to exec or returning an error */
 163         err = read(sv[1], &sync, sizeof(sync));
 164         if (err < 0) {
 165                 lxc_log_error("failed to read the socket");
 166                 goto err_pipe_read2;
 167         }
 168
 169         if (err > 0) {
 170                 err = sync;
 171                 printf("error value is %d\n", err);
 172                 /* TODO : check status etc ... */
 173                 waitpid(pid, NULL, 0);
 174                 goto err_child_failed;
 175         }
 176
 177         asprintf(&val, "%d\n", pid);
 178
 179         snprintf(init, MAXPATHLEN, LXCPATH "/%s/init", name);
 180
 181         fd = open(init, O_WRONLY|O_CREAT|O_TRUNC, 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_setstate(name, RUNNING)) {
 195                 lxc_log_error("failed to set state to %s",
 196                               lxc_state2str(RUNNING));
 197                 goto err_state_failed;
 198         }
 199
 200 wait_again:
 201         if (waitpid(pid, NULL, 0) < 0) {
 202                 if (errno == EINTR)
 203                         goto wait_again;
 204                 lxc_log_syserror("failed to wait the pid %d", pid);
 205                 goto err_waitpid_failed;
 206         }
 207
 208         if (lxc_setstate(name, STOPPING))
 209                 lxc_log_error("failed to set state %s", lxc_state2str(STOPPING));
 210
 211 #ifdef NETWORK_DESTROY
 212         if (clone_flags & CLONE_NEWNET && conf_destroy_network(name))
 213                 lxc_log_error("failed to destroy the network");
 214 #endif
 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(val);
 224         lxc_put_lock(lock);
 225         LXC_TTY_DEL_HANDLER(SIGQUIT);
 226         LXC_TTY_DEL_HANDLER(SIGINT);
 227
 228         return err;
 229
 230 err_write:
 231         close(fd);
 232
 233 err_state_failed:
 234 err_child_failed:
 235 err_pipe_read2:
 236 err_pipe_write:
 237 #ifdef NETWORK_DESTROY
 238         if (clone_flags & CLONE_NEWNET)
 239                 conf_destroy_network(name);
 240 #endif
 241 err_create_network:
 242 err_pipe_read:
 243 err_waitpid_failed:
 244         if (lxc_setstate(name, ABORTING))
 245                 lxc_log_error("failed to set state %s", lxc_state2str(STOPPED));
 246
 247         kill(pid, SIGKILL);
 248 err_fork_ns:
 249         close(sv[0]);
 250         close(sv[1]);
 251         goto out;
 252 }