src/lxc/initutils.c

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23
  24 #include "initutils.h"
  25 #include "log.h"
  26
  27 lxc_log_define(lxc_initutils, lxc);
  28
  29 static int mount_fs(const char *source, const char *target, const char *type)
  30 {
  31         /* the umount may fail */
  32         if (umount(target))
  33                 WARN("Failed to unmount %s : %s", target, strerror(errno));
  34
  35         if (mount(source, target, type, 0, NULL)) {
  36                 ERROR("Failed to mount %s : %s", target, strerror(errno));
  37                 return -1;
  38         }
  39
  40         DEBUG("'%s' mounted on '%s'", source, target);
  41
  42         return 0;
  43 }
  44
  45 extern void lxc_setup_fs(void)
  46 {
  47         if (mount_fs("proc", "/proc", "proc"))
  48                 INFO("Failed to remount proc");
  49
  50         /* if /dev has been populated by us, /dev/shm does not exist */
  51         if (access("/dev/shm", F_OK) && mkdir("/dev/shm", 0777))
  52                 INFO("Failed to create /dev/shm");
  53
  54         /* if we can't mount /dev/shm, continue anyway */
  55         if (mount_fs("shmfs", "/dev/shm", "tmpfs"))
  56                 INFO("Failed to mount /dev/shm");
  57
  58         /* If we were able to mount /dev/shm, then /dev exists */
  59         /* Sure, but it's read-only per config :) */
  60         if (access("/dev/mqueue", F_OK) && mkdir("/dev/mqueue", 0666)) {
  61                 DEBUG("Failed to create '/dev/mqueue'");
  62                 return;
  63         }
  64
  65         /* continue even without posix message queue support */
  66         if (mount_fs("mqueue", "/dev/mqueue", "mqueue"))
  67                 INFO("Failed to mount /dev/mqueue");
  68 }
  69
  70 static char *copy_global_config_value(char *p)
  71 {
  72         int len = strlen(p);
  73         char *retbuf;
  74
  75         if (len < 1)
  76                 return NULL;
  77         if (p[len-1] == '\n') {
  78                 p[len-1] = '\0';
  79                 len--;
  80         }
  81         retbuf = malloc(len+1);
  82         if (!retbuf)
  83                 return NULL;
  84         strcpy(retbuf, p);
  85         return retbuf;
  86 }
  87
  88 const char *lxc_global_config_value(const char *option_name)
  89 {
  90         static const char * const options[][2] = {
  91                 { "lxc.bdev.lvm.vg",        DEFAULT_VG      },
  92                 { "lxc.bdev.lvm.thin_pool", DEFAULT_THIN_POOL },
  93                 { "lxc.bdev.zfs.root",      DEFAULT_ZFSROOT },
  94                 { "lxc.bdev.rbd.rbdpool",   DEFAULT_RBDPOOL },
  95                 { "lxc.lxcpath",            NULL            },
  96                 { "lxc.default_config",     NULL            },
  97                 { "lxc.cgroup.pattern",     NULL            },
  98                 { "lxc.cgroup.use",         NULL            },
  99                 { NULL, NULL },
 100         };
 101
 102         /* placed in the thread local storage pool for non-bionic targets */
 103 #ifdef HAVE_TLS
 104         static __thread const char *values[sizeof(options) / sizeof(options[0])] = { 0 };
 105 #else
 106         static const char *values[sizeof(options) / sizeof(options[0])] = { 0 };
 107 #endif
 108
 109         /* user_config_path is freed as soon as it is used */
 110         char *user_config_path = NULL;
 111
 112         /*
 113          * The following variables are freed at bottom unconditionally.
 114          * So NULL the value if it is to be returned to the caller
 115          */
 116         char *user_default_config_path = NULL;
 117         char *user_lxc_path = NULL;
 118         char *user_cgroup_pattern = NULL;
 119
 120         if (geteuid() > 0) {
 121                 const char *user_home = getenv("HOME");
 122                 if (!user_home)
 123                         user_home = "/";
 124
 125                 user_config_path = malloc(sizeof(char) * (22 + strlen(user_home)));
 126                 user_default_config_path = malloc(sizeof(char) * (26 + strlen(user_home)));
 127                 user_lxc_path = malloc(sizeof(char) * (19 + strlen(user_home)));
 128
 129                 sprintf(user_config_path, "%s/.config/lxc/lxc.conf", user_home);
 130                 sprintf(user_default_config_path, "%s/.config/lxc/default.conf", user_home);
 131                 sprintf(user_lxc_path, "%s/.local/share/lxc/", user_home);
 132                 user_cgroup_pattern = strdup("lxc/%n");
 133         }
 134         else {
 135                 user_config_path = strdup(LXC_GLOBAL_CONF);
 136                 user_default_config_path = strdup(LXC_DEFAULT_CONFIG);
 137                 user_lxc_path = strdup(LXCPATH);
 138                 user_cgroup_pattern = strdup(DEFAULT_CGROUP_PATTERN);
 139         }
 140
 141         const char * const (*ptr)[2];
 142         size_t i;
 143         char buf[1024], *p, *p2;
 144         FILE *fin = NULL;
 145
 146         for (i = 0, ptr = options; (*ptr)[0]; ptr++, i++) {
 147                 if (!strcmp(option_name, (*ptr)[0]))
 148                         break;
 149         }
 150         if (!(*ptr)[0]) {
 151                 free(user_config_path);
 152                 free(user_default_config_path);
 153                 free(user_lxc_path);
 154                 free(user_cgroup_pattern);
 155                 errno = EINVAL;
 156                 return NULL;
 157         }
 158
 159         if (values[i]) {
 160                 free(user_config_path);
 161                 free(user_default_config_path);
 162                 free(user_lxc_path);
 163                 free(user_cgroup_pattern);
 164                 return values[i];
 165         }
 166
 167         fin = fopen_cloexec(user_config_path, "r");
 168         free(user_config_path);
 169         if (fin) {
 170                 while (fgets(buf, 1024, fin)) {
 171                         if (buf[0] == '#')
 172                                 continue;
 173                         p = strstr(buf, option_name);
 174                         if (!p)
 175                                 continue;
 176                         /* see if there was just white space in front
 177                          * of the option name
 178                          */
 179                         for (p2 = buf; p2 < p; p2++) {
 180                                 if (*p2 != ' ' && *p2 != '\t')
 181                                         break;
 182                         }
 183                         if (p2 < p)
 184                                 continue;
 185                         p = strchr(p, '=');
 186                         if (!p)
 187                                 continue;
 188                         /* see if there was just white space after
 189                          * the option name
 190                          */
 191                         for (p2 += strlen(option_name); p2 < p; p2++) {
 192                                 if (*p2 != ' ' && *p2 != '\t')
 193                                         break;
 194                         }
 195                         if (p2 < p)
 196                                 continue;
 197                         p++;
 198                         while (*p && (*p == ' ' || *p == '\t')) p++;
 199                         if (!*p)
 200                                 continue;
 201
 202                         if (strcmp(option_name, "lxc.lxcpath") == 0) {
 203                                 free(user_lxc_path);
 204                                 user_lxc_path = copy_global_config_value(p);
 205                                 remove_trailing_slashes(user_lxc_path);
 206                                 values[i] = user_lxc_path;
 207                                 user_lxc_path = NULL;
 208                                 goto out;
 209                         }
 210
 211                         values[i] = copy_global_config_value(p);
 212                         goto out;
 213                 }
 214         }
 215         /* could not find value, use default */
 216         if (strcmp(option_name, "lxc.lxcpath") == 0) {
 217                 remove_trailing_slashes(user_lxc_path);
 218                 values[i] = user_lxc_path;
 219                 user_lxc_path = NULL;
 220         }
 221         else if (strcmp(option_name, "lxc.default_config") == 0) {
 222                 values[i] = user_default_config_path;
 223                 user_default_config_path = NULL;
 224         }
 225         else if (strcmp(option_name, "lxc.cgroup.pattern") == 0) {
 226                 values[i] = user_cgroup_pattern;
 227                 user_cgroup_pattern = NULL;
 228         }
 229         else
 230                 values[i] = (*ptr)[1];
 231
 232         /* special case: if default value is NULL,
 233          * and there is no config, don't view that
 234          * as an error... */
 235         if (!values[i])
 236                 errno = 0;
 237
 238 out:
 239         if (fin)
 240                 fclose(fin);
 241
 242         free(user_cgroup_pattern);
 243         free(user_default_config_path);
 244         free(user_lxc_path);
 245
 246         return values[i];
 247 }
 248
 249 extern void remove_trailing_slashes(char *p)
 250 {
 251         int l = strlen(p);
 252         while (--l >= 0 && (p[l] == '/' || p[l] == '\n'))
 253                 p[l] = '\0';
 254 }
 255
 256 FILE *fopen_cloexec(const char *path, const char *mode)
 257 {
 258         int open_mode = 0;
 259         int step = 0;
 260         int fd;
 261         int saved_errno = 0;
 262         FILE *ret;
 263
 264         if (!strncmp(mode, "r+", 2)) {
 265                 open_mode = O_RDWR;
 266                 step = 2;
 267         } else if (!strncmp(mode, "r", 1)) {
 268                 open_mode = O_RDONLY;
 269                 step = 1;
 270         } else if (!strncmp(mode, "w+", 2)) {
 271                 open_mode = O_RDWR | O_TRUNC | O_CREAT;
 272                 step = 2;
 273         } else if (!strncmp(mode, "w", 1)) {
 274                 open_mode = O_WRONLY | O_TRUNC | O_CREAT;
 275                 step = 1;
 276         } else if (!strncmp(mode, "a+", 2)) {
 277                 open_mode = O_RDWR | O_CREAT | O_APPEND;
 278                 step = 2;
 279         } else if (!strncmp(mode, "a", 1)) {
 280                 open_mode = O_WRONLY | O_CREAT | O_APPEND;
 281                 step = 1;
 282         }
 283         for (; mode[step]; step++)
 284                 if (mode[step] == 'x')
 285                         open_mode |= O_EXCL;
 286         open_mode |= O_CLOEXEC;
 287
 288         fd = open(path, open_mode, 0666);
 289         if (fd < 0)
 290                 return NULL;
 291
 292         ret = fdopen(fd, mode);
 293         saved_errno = errno;
 294         if (!ret)
 295                 close(fd);
 296         errno = saved_errno;
 297         return ret;
 298 }