Merge pull request #92 from majek/share-namespaces

Add options to `lxc-start` to inherit network, ipc and uts namespaces

diff --cc src/lxc/conf.c
index 860fc5b63484311be55c5d45628a774be54787fa,dfc49e435fce0ef1e42700e7b96892480d27a1f5..534e6e6fb7e8db5aee6d51d6d7ba45c117b75723
--- 1/src/lxc/conf.c
--- 2/src/lxc/conf.c
+++ b/src/lxc/conf.c
@@@ -3377,93 -3139,13 +3380,95 @@@ int ttys_shift_ids(struct lxc_conf *c
        return 0;
  }
  
 -int lxc_setup(const char *name, struct lxc_conf *lxc_conf, const char *lxcpath, struct cgroup_process_info *cgroup_info)
 +/*
 + * This routine is called when the configuration does not already specify a value
 + * for autodev (mounting a file system on /dev and populating it in a container).
 + * If a hard override value has not be specified, then we try to apply some
 + * heuristics to determine if we should switch to autodev mode.
 + *
 + * For instance, if the container has an /etc/systemd/system directory then it
 + * is probably running systemd as the init process and it needs the autodev
 + * mount to prevent it from mounting devtmpfs on /dev on it's own causing conflicts
 + * in the host.
 + *
 + * We may also want to enable autodev if the host has devtmpfs mounted on its
 + * /dev as this then enable us to use subdirectories under /dev for the container
 + * /dev directories and we can fake udev devices.
 + */
 +struct start_args {
 +      char *const *argv;
 +};
 +
 +#define MAX_SYMLINK_DEPTH 32
 +
 +int check_autodev( const char *rootfs, void *data )
 +{
 +      struct start_args *arg = data;
 +      int ret;
 +      int loop_count = 0;
 +      struct stat s;
 +      char absrootfs[MAXPATHLEN];
 +      char path[MAXPATHLEN];
 +      char abs_path[MAXPATHLEN];
 +      char *command = "/sbin/init";
 +
 +      if (rootfs == NULL || strlen(rootfs) == 0)
 +              return -2;
 +
 +      if (!realpath(rootfs, absrootfs))
 +              return -2;
 +
 +      if( arg && arg->argv[0] ) {
 +              command = arg->argv[0];
 +              DEBUG("Set exec command to %s\n", command );
 +      }
 +
 +      strncpy( path, command, MAXPATHLEN-1 );
 +
 +      if ( 0 != access(path, F_OK) || 0 != stat(path, &s) )
 +              return -2;
 +
 +      /* Dereference down the symlink merry path testing as we go. */
 +      /* If anything references systemd in the path - set autodev! */
 +      /* Renormalize to the rootfs before each dereference */
 +      /* Relative symlinks should fall out in the wash even with .. */
 +      while( 1 ) {
 +              if ( strstr( path, "systemd" ) ) {
 +                      INFO("Container with systemd init detected - enabling autodev!");
 +                      return 1;
 +              }
 +
 +              ret = snprintf(abs_path, MAXPATHLEN-1, "%s/%s", absrootfs, path);
 +              if (ret < 0 || ret > MAXPATHLEN)
 +                      return -2;
 +
 +              ret = readlink( abs_path, path, MAXPATHLEN-1 );
 +
 +              if ( ( ret <= 0 ) || ( ++loop_count > MAX_SYMLINK_DEPTH ) ) {
 +                      break; /* Break out for other tests */
 +              }
 +              path[ret] = '\0';
 +      }
 +
 +      /*
 +       * Add future checks here.
 +       *      Return positive if we should go autodev
 +       *      Return 0 if we should NOT go autodev
 +       *      Return negative if we encounter an error or can not determine...
 +       */
 +
 +      /* All else fails, we don't need autodev */
 +      INFO("Autodev not required.");
 +      return 0;
 +}
 +
 +int lxc_setup(const char *name, struct lxc_conf *lxc_conf, const char *lxcpath, struct cgroup_process_info *cgroup_info, void *data)
  {
-       if (setup_utsname(lxc_conf->utsname)) {
-               ERROR("failed to setup the utsname for '%s'", name);
-               return -1;
+       if (lxc_conf->inherit_ns_fd[LXC_NS_UTS] == -1) {
+               if (setup_utsname(lxc_conf->utsname)) {
+                       ERROR("failed to setup the utsname for '%s'", name);
+                       return -1;
+               }
        }
  
        if (setup_network(&lxc_conf->network)) {

diff --cc src/lxc/conf.h
Simple merge

diff --cc src/lxc/lxc_start.c
Simple merge

diff --cc src/lxc/start.c
Simple merge