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 #ifndef _GNU_SOURCE
  25 #define _GNU_SOURCE 1
  26 #endif
  27 #include <sys/prctl.h>
  28
  29 #include "compiler.h"
  30 #include "config.h"
  31 #include "file_utils.h"
  32 #include "initutils.h"
  33 #include "log.h"
  34 #include "macro.h"
  35
  36 #ifndef HAVE_STRLCPY
  37 #include "include/strlcpy.h"
  38 #endif
  39
  40 lxc_log_define(initutils, lxc);
  41
  42 static char *copy_global_config_value(char *p)
  43 {
  44         int len = strlen(p);
  45         char *retbuf;
  46
  47         if (len < 1)
  48                 return NULL;
  49
  50         if (p[len-1] == '\n') {
  51                 p[len-1] = '\0';
  52                 len--;
  53         }
  54
  55         retbuf = malloc(len + 1);
  56         if (!retbuf)
  57                 return NULL;
  58
  59         (void)strlcpy(retbuf, p, len + 1);
  60         return retbuf;
  61 }
  62
  63 const char *lxc_global_config_value(const char *option_name)
  64 {
  65         static const char * const options[][2] = {
  66                 { "lxc.bdev.lvm.vg",        DEFAULT_VG      },
  67                 { "lxc.bdev.lvm.thin_pool", DEFAULT_THIN_POOL },
  68                 { "lxc.bdev.zfs.root",      DEFAULT_ZFSROOT },
  69                 { "lxc.bdev.rbd.rbdpool",   DEFAULT_RBDPOOL },
  70                 { "lxc.lxcpath",            NULL            },
  71                 { "lxc.default_config",     NULL            },
  72                 { "lxc.cgroup.pattern",     NULL            },
  73                 { "lxc.cgroup.use",         NULL            },
  74                 { NULL, NULL },
  75         };
  76
  77         /* placed in the thread local storage pool for non-bionic targets */
  78 #ifdef HAVE_TLS
  79         static thread_local const char *values[sizeof(options) / sizeof(options[0])] = {0};
  80 #else
  81         static const char *values[sizeof(options) / sizeof(options[0])] = {0};
  82 #endif
  83
  84         /* user_config_path is freed as soon as it is used */
  85         char *user_config_path = NULL;
  86
  87         /*
  88          * The following variables are freed at bottom unconditionally.
  89          * So NULL the value if it is to be returned to the caller
  90          */
  91         char *user_default_config_path = NULL;
  92         char *user_lxc_path = NULL;
  93         char *user_cgroup_pattern = NULL;
  94
  95         if (geteuid() > 0) {
  96                 const char *user_home = getenv("HOME");
  97                 if (!user_home)
  98                         user_home = "/";
  99
 100                 user_config_path = malloc(sizeof(char) * (22 + strlen(user_home)));
 101                 user_default_config_path = malloc(sizeof(char) * (26 + strlen(user_home)));
 102                 user_lxc_path = malloc(sizeof(char) * (19 + strlen(user_home)));
 103
 104                 sprintf(user_config_path, "%s/.config/lxc/lxc.conf", user_home);
 105                 sprintf(user_default_config_path, "%s/.config/lxc/default.conf", user_home);
 106                 sprintf(user_lxc_path, "%s/.local/share/lxc/", user_home);
 107                 user_cgroup_pattern = strdup("lxc.payload/%n");
 108         }
 109         else {
 110                 user_config_path = strdup(LXC_GLOBAL_CONF);
 111                 user_default_config_path = strdup(LXC_DEFAULT_CONFIG);
 112                 user_lxc_path = strdup(LXCPATH);
 113                 user_cgroup_pattern = strdup(DEFAULT_CGROUP_PATTERN);
 114         }
 115
 116         const char * const (*ptr)[2];
 117         size_t i;
 118         char buf[1024], *p, *p2;
 119         FILE *fin = NULL;
 120
 121         for (i = 0, ptr = options; (*ptr)[0]; ptr++, i++) {
 122                 if (!strcmp(option_name, (*ptr)[0]))
 123                         break;
 124         }
 125         if (!(*ptr)[0]) {
 126                 free(user_config_path);
 127                 free(user_default_config_path);
 128                 free(user_lxc_path);
 129                 free(user_cgroup_pattern);
 130                 errno = EINVAL;
 131                 return NULL;
 132         }
 133
 134         if (values[i]) {
 135                 free(user_config_path);
 136                 free(user_default_config_path);
 137                 free(user_lxc_path);
 138                 free(user_cgroup_pattern);
 139                 return values[i];
 140         }
 141
 142         fin = fopen_cloexec(user_config_path, "r");
 143         free(user_config_path);
 144         if (fin) {
 145                 while (fgets(buf, 1024, fin)) {
 146                         if (buf[0] == '#')
 147                                 continue;
 148                         p = strstr(buf, option_name);
 149                         if (!p)
 150                                 continue;
 151                         /* see if there was just white space in front
 152                          * of the option name
 153                          */
 154                         for (p2 = buf; p2 < p; p2++) {
 155                                 if (*p2 != ' ' && *p2 != '\t')
 156                                         break;
 157                         }
 158                         if (p2 < p)
 159                                 continue;
 160                         p = strchr(p, '=');
 161                         if (!p)
 162                                 continue;
 163                         /* see if there was just white space after
 164                          * the option name
 165                          */
 166                         for (p2 += strlen(option_name); p2 < p; p2++) {
 167                                 if (*p2 != ' ' && *p2 != '\t')
 168                                         break;
 169                         }
 170                         if (p2 < p)
 171                                 continue;
 172                         p++;
 173                         while (*p && (*p == ' ' || *p == '\t')) p++;
 174                         if (!*p)
 175                                 continue;
 176
 177                         if (strcmp(option_name, "lxc.lxcpath") == 0) {
 178                                 free(user_lxc_path);
 179                                 user_lxc_path = copy_global_config_value(p);
 180                                 remove_trailing_slashes(user_lxc_path);
 181                                 values[i] = user_lxc_path;
 182                                 user_lxc_path = NULL;
 183                                 goto out;
 184                         }
 185
 186                         values[i] = copy_global_config_value(p);
 187                         goto out;
 188                 }
 189         }
 190         /* could not find value, use default */
 191         if (strcmp(option_name, "lxc.lxcpath") == 0) {
 192                 remove_trailing_slashes(user_lxc_path);
 193                 values[i] = user_lxc_path;
 194                 user_lxc_path = NULL;
 195         }
 196         else if (strcmp(option_name, "lxc.default_config") == 0) {
 197                 values[i] = user_default_config_path;
 198                 user_default_config_path = NULL;
 199         }
 200         else if (strcmp(option_name, "lxc.cgroup.pattern") == 0) {
 201                 values[i] = user_cgroup_pattern;
 202                 user_cgroup_pattern = NULL;
 203         }
 204         else
 205                 values[i] = (*ptr)[1];
 206
 207         /* special case: if default value is NULL,
 208          * and there is no config, don't view that
 209          * as an error... */
 210         if (!values[i])
 211                 errno = 0;
 212
 213 out:
 214         if (fin)
 215                 fclose(fin);
 216
 217         free(user_cgroup_pattern);
 218         free(user_default_config_path);
 219         free(user_lxc_path);
 220
 221         return values[i];
 222 }
 223
 224 /*
 225  * Sets the process title to the specified title. Note that this may fail if
 226  * the kernel doesn't support PR_SET_MM_MAP (kernels <3.18).
 227  */
 228 int setproctitle(char *title)
 229 {
 230         static char *proctitle = NULL;
 231         char buf[2048], *tmp;
 232         FILE *f;
 233         int i, len, ret = 0;
 234
 235         /* We don't really need to know all of this stuff, but unfortunately
 236          * PR_SET_MM_MAP requires us to set it all at once, so we have to
 237          * figure it out anyway.
 238          */
 239         unsigned long start_data, end_data, start_brk, start_code, end_code,
 240                         start_stack, arg_start, arg_end, env_start, env_end,
 241                         brk_val;
 242         struct prctl_mm_map prctl_map;
 243
 244         f = fopen_cloexec("/proc/self/stat", "r");
 245         if (!f) {
 246                 return -1;
 247         }
 248
 249         tmp = fgets(buf, sizeof(buf), f);
 250         fclose(f);
 251         if (!tmp) {
 252                 return -1;
 253         }
 254
 255         /* Skip the first 25 fields, column 26-28 are start_code, end_code,
 256          * and start_stack */
 257         tmp = strchr(buf, ' ');
 258         for (i = 0; i < 24; i++) {
 259                 if (!tmp)
 260                         return -1;
 261                 tmp = strchr(tmp+1, ' ');
 262         }
 263         if (!tmp)
 264                 return -1;
 265
 266         i = sscanf(tmp, "%lu %lu %lu", &start_code, &end_code, &start_stack);
 267         if (i != 3)
 268                 return -1;
 269
 270         /* Skip the next 19 fields, column 45-51 are start_data to arg_end */
 271         for (i = 0; i < 19; i++) {
 272                 if (!tmp)
 273                         return -1;
 274                 tmp = strchr(tmp+1, ' ');
 275         }
 276
 277         if (!tmp)
 278                 return -1;
 279
 280         i = sscanf(tmp, "%lu %lu %lu %*u %*u %lu %lu",
 281                 &start_data,
 282                 &end_data,
 283                 &start_brk,
 284                 &env_start,
 285                 &env_end);
 286         if (i != 5)
 287                 return -1;
 288
 289         /* Include the null byte here, because in the calculations below we
 290          * want to have room for it. */
 291         len = strlen(title) + 1;
 292
 293         proctitle = realloc(proctitle, len);
 294         if (!proctitle)
 295                 return -1;
 296
 297         arg_start = (unsigned long) proctitle;
 298         arg_end = arg_start + len;
 299
 300         brk_val = syscall(__NR_brk, 0);
 301
 302         prctl_map = (struct prctl_mm_map) {
 303                 .start_code = start_code,
 304                 .end_code = end_code,
 305                 .start_stack = start_stack,
 306                 .start_data = start_data,
 307                 .end_data = end_data,
 308                 .start_brk = start_brk,
 309                 .brk = brk_val,
 310                 .arg_start = arg_start,
 311                 .arg_end = arg_end,
 312                 .env_start = env_start,
 313                 .env_end = env_end,
 314                 .auxv = NULL,
 315                 .auxv_size = 0,
 316                 .exe_fd = -1,
 317         };
 318
 319         ret = prctl(PR_SET_MM, prctl_arg(PR_SET_MM_MAP), prctl_arg(&prctl_map),
 320                     prctl_arg(sizeof(prctl_map)), prctl_arg(0));
 321         if (ret == 0)
 322                 (void)strlcpy((char*)arg_start, title, len);
 323         else
 324                 SYSWARN("Failed to set cmdline");
 325
 326         return ret;
 327 }