src/shared/unit-file.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include "dirent-util.h"
   4 #include "fd-util.h"
   5 #include "fs-util.h"
   6 #include "macro.h"
   7 #include "path-lookup.h"
   8 #include "set.h"
   9 #include "special.h"
  10 #include "stat-util.h"
  11 #include "string-util.h"
  12 #include "strv.h"
  13 #include "unit-file.h"
  14
  15 bool unit_type_may_alias(UnitType type) {
  16         return IN_SET(type,
  17                       UNIT_SERVICE,
  18                       UNIT_SOCKET,
  19                       UNIT_TARGET,
  20                       UNIT_DEVICE,
  21                       UNIT_TIMER,
  22                       UNIT_PATH);
  23 }
  24
  25 bool unit_type_may_template(UnitType type) {
  26         return IN_SET(type,
  27                       UNIT_SERVICE,
  28                       UNIT_SOCKET,
  29                       UNIT_TARGET,
  30                       UNIT_TIMER,
  31                       UNIT_PATH);
  32 }
  33
  34 int unit_validate_alias_symlink_and_warn(const char *filename, const char *target) {
  35         const char *src, *dst;
  36         _cleanup_free_ char *src_instance = NULL, *dst_instance = NULL;
  37         UnitType src_unit_type, dst_unit_type;
  38         int src_name_type, dst_name_type;
  39
  40         /* Check if the *alias* symlink is valid. This applies to symlinks like
  41          * /etc/systemd/system/dbus.service → dbus-broker.service, but not to .wants or .requires symlinks
  42          * and such. Neither does this apply to symlinks which *link* units, i.e. symlinks to outside of the
  43          * unit lookup path.
  44          *
  45          * -EINVAL is returned if the something is wrong with the source filename or the source unit type is
  46          *         not allowed to symlink,
  47          * -EXDEV if the target filename is not a valid unit name or doesn't match the source.
  48          */
  49
  50         src = basename(filename);
  51         dst = basename(target);
  52
  53         /* src checks */
  54
  55         src_name_type = unit_name_to_instance(src, &src_instance);
  56         if (src_name_type < 0)
  57                 return log_notice_errno(src_name_type,
  58                                         "%s: not a valid unit name \"%s\": %m", filename, src);
  59
  60         src_unit_type = unit_name_to_type(src);
  61         assert(src_unit_type >= 0); /* unit_name_to_instance() checked the suffix already */
  62
  63         if (!unit_type_may_alias(src_unit_type))
  64                 return log_notice_errno(SYNTHETIC_ERRNO(EINVAL),
  65                                         "%s: symlinks are not allowed for units of this type, rejecting.",
  66                                         filename);
  67
  68         if (src_name_type != UNIT_NAME_PLAIN &&
  69             !unit_type_may_template(src_unit_type))
  70                 return log_notice_errno(SYNTHETIC_ERRNO(EINVAL),
  71                                         "%s: templates not allowed for %s units, rejecting.",
  72                                         filename, unit_type_to_string(src_unit_type));
  73
  74         /* dst checks */
  75
  76         dst_name_type = unit_name_to_instance(dst, &dst_instance);
  77         if (dst_name_type < 0)
  78                 return log_notice_errno(dst_name_type == -EINVAL ? SYNTHETIC_ERRNO(EXDEV) : dst_name_type,
  79                                         "%s points to \"%s\" which is not a valid unit name: %m",
  80                                         filename, dst);
  81
  82         if (!(dst_name_type == src_name_type ||
  83               (src_name_type == UNIT_NAME_INSTANCE && dst_name_type == UNIT_NAME_TEMPLATE)))
  84                 return log_notice_errno(SYNTHETIC_ERRNO(EXDEV),
  85                                         "%s: symlink target name type \"%s\" does not match source, rejecting.",
  86                                         filename, dst);
  87
  88         if (dst_name_type == UNIT_NAME_INSTANCE) {
  89                 assert(src_instance);
  90                 assert(dst_instance);
  91                 if (!streq(src_instance, dst_instance))
  92                         return log_notice_errno(SYNTHETIC_ERRNO(EXDEV),
  93                                                 "%s: unit symlink target \"%s\" instance name doesn't match, rejecting.",
  94                                                 filename, dst);
  95         }
  96
  97         dst_unit_type = unit_name_to_type(dst);
  98         if (dst_unit_type != src_unit_type)
  99                 return log_notice_errno(SYNTHETIC_ERRNO(EXDEV),
 100                                         "%s: symlink target \"%s\" has incompatible suffix, rejecting.",
 101                                         filename, dst);
 102
 103         return 0;
 104 }
 105
 106 #define FOLLOW_MAX 8
 107
 108 static int unit_ids_map_get(
 109                 Hashmap *unit_ids_map,
 110                 const char *unit_name,
 111                 const char **ret_fragment_path) {
 112
 113         /* Resolve recursively until we hit an absolute path, i.e. a non-aliased unit.
 114          *
 115          * We distinguish the case where unit_name was not found in the hashmap at all, and the case where
 116          * some symlink was broken.
 117          *
 118          * If a symlink target points to an instance name, then we also check for the template. */
 119
 120         const char *id = NULL;
 121         int r;
 122
 123         for (unsigned n = 0; n < FOLLOW_MAX; n++) {
 124                 const char *t = hashmap_get(unit_ids_map, id ?: unit_name);
 125                 if (!t) {
 126                         _cleanup_free_ char *template = NULL;
 127
 128                         if (!id)
 129                                 return -ENOENT;
 130
 131                         r = unit_name_template(id, &template);
 132                         if (r == -EINVAL)
 133                                 return -ENXIO; /* we failed to find the symlink target */
 134                         if (r < 0)
 135                                 return log_error_errno(r, "Failed to determine template name for %s: %m", id);
 136
 137                         t = hashmap_get(unit_ids_map, template);
 138                         if (!t)
 139                                 return -ENXIO;
 140
 141                         /* We successfully switched from instanced name to a template, let's continue */
 142                 }
 143
 144                 if (path_is_absolute(t)) {
 145                         if (ret_fragment_path)
 146                                 *ret_fragment_path = t;
 147                         return 0;
 148                 }
 149
 150                 id = t;
 151         }
 152
 153         return -ELOOP;
 154 }
 155
 156 static bool lookup_paths_mtime_exclude(const LookupPaths *lp, const char *path) {
 157         /* Paths that are under our exclusive control. Users shall not alter those directly. */
 158
 159         return streq_ptr(path, lp->generator) ||
 160                streq_ptr(path, lp->generator_early) ||
 161                streq_ptr(path, lp->generator_late) ||
 162                streq_ptr(path, lp->transient) ||
 163                streq_ptr(path, lp->persistent_control) ||
 164                streq_ptr(path, lp->runtime_control);
 165 }
 166
 167 static bool lookup_paths_mtime_good(const LookupPaths *lp, usec_t mtime) {
 168         char **dir;
 169
 170         STRV_FOREACH(dir, (char**) lp->search_path) {
 171                 struct stat st;
 172
 173                 if (lookup_paths_mtime_exclude(lp, *dir))
 174                         continue;
 175
 176                 /* Determine the latest lookup path modification time */
 177                 if (stat(*dir, &st) < 0) {
 178                         if (errno == ENOENT)
 179                                 continue;
 180
 181                         log_debug_errno(errno, "Failed to stat %s, ignoring: %m", *dir);
 182                         continue;
 183                 }
 184
 185                 if (timespec_load(&st.st_mtim) > mtime) {
 186                         log_debug_errno(errno, "Unit dir %s has changed, need to update cache.", *dir);
 187                         return false;
 188                 }
 189         }
 190
 191         return true;
 192 }
 193
 194 int unit_file_build_name_map(
 195                 const LookupPaths *lp,
 196                 usec_t *cache_mtime,
 197                 Hashmap **ret_unit_ids_map,
 198                 Hashmap **ret_unit_names_map,
 199                 Set **ret_path_cache) {
 200
 201         /* Build two mappings: any name → main unit (i.e. the end result of symlink resolution), unit name →
 202          * all aliases (i.e. the entry for a given key is a a list of all names which point to this key). The
 203          * key is included in the value iff we saw a file or symlink with that name. In other words, if we
 204          * have a key, but it is not present in the value for itself, there was an alias pointing to it, but
 205          * the unit itself is not loadable.
 206          *
 207          * At the same, build a cache of paths where to find units.
 208          */
 209
 210         _cleanup_hashmap_free_ Hashmap *ids = NULL, *names = NULL;
 211         _cleanup_set_free_free_ Set *paths = NULL;
 212         char **dir;
 213         int r;
 214         usec_t mtime = 0;
 215
 216         /* Before doing anything, check if the mtime that was passed is still valid. If
 217          * yes, do nothing. If *cache_time == 0, always build the cache. */
 218         if (cache_mtime && *cache_mtime > 0 && lookup_paths_mtime_good(lp, *cache_mtime))
 219                 return 0;
 220
 221         if (ret_path_cache) {
 222                 paths = set_new(&path_hash_ops);
 223                 if (!paths)
 224                         return log_oom();
 225         }
 226
 227         STRV_FOREACH(dir, (char**) lp->search_path) {
 228                 struct dirent *de;
 229                 _cleanup_closedir_ DIR *d = NULL;
 230                 struct stat st;
 231
 232                 d = opendir(*dir);
 233                 if (!d) {
 234                         if (errno != ENOENT)
 235                                 log_warning_errno(errno, "Failed to open \"%s\", ignoring: %m", *dir);
 236                         continue;
 237                 }
 238
 239                 /* Determine the latest lookup path modification time */
 240                 if (fstat(dirfd(d), &st) < 0)
 241                         return log_error_errno(errno, "Failed to fstat %s: %m", *dir);
 242
 243                 if (!lookup_paths_mtime_exclude(lp, *dir))
 244                         mtime = MAX(mtime, timespec_load(&st.st_mtim));
 245
 246                 FOREACH_DIRENT_ALL(de, d, log_warning_errno(errno, "Failed to read \"%s\", ignoring: %m", *dir)) {
 247                         char *filename;
 248                         _cleanup_free_ char *_filename_free = NULL, *simplified = NULL;
 249                         const char *suffix, *dst = NULL;
 250                         bool valid_unit_name;
 251
 252                         valid_unit_name = unit_name_is_valid(de->d_name, UNIT_NAME_ANY);
 253
 254                         /* We only care about valid units and dirs with certain suffixes, let's ignore the
 255                          * rest. */
 256                         if (!valid_unit_name &&
 257                             !ENDSWITH_SET(de->d_name, ".wants", ".requires", ".d"))
 258                                 continue;
 259
 260                         filename = path_join(*dir, de->d_name);
 261                         if (!filename)
 262                                 return log_oom();
 263
 264                         if (ret_path_cache) {
 265                                 r = set_consume(paths, filename);
 266                                 if (r < 0)
 267                                         return log_oom();
 268                                 /* We will still use filename below. This is safe because we know the set
 269                                  * holds a reference. */
 270                         } else
 271                                 _filename_free = filename; /* Make sure we free the filename. */
 272
 273                         if (!valid_unit_name)
 274                                 continue;
 275                         assert_se(suffix = strrchr(de->d_name, '.'));
 276
 277                         /* search_path is ordered by priority (highest first). If the name is already mapped
 278                          * to something (incl. itself), it means that we have already seen it, and we should
 279                          * ignore it here. */
 280                         if (hashmap_contains(ids, de->d_name))
 281                                 continue;
 282
 283                         dirent_ensure_type(d, de);
 284                         if (de->d_type == DT_LNK) {
 285                                 /* We don't explicitly check for alias loops here. unit_ids_map_get() which
 286                                  * limits the number of hops should be used to access the map. */
 287
 288                                 _cleanup_free_ char *target = NULL, *target_abs = NULL;
 289
 290                                 r = readlinkat_malloc(dirfd(d), de->d_name, &target);
 291                                 if (r < 0) {
 292                                         log_warning_errno(r, "Failed to read symlink %s/%s, ignoring: %m",
 293                                                           *dir, de->d_name);
 294                                         continue;
 295                                 }
 296
 297                                 if (!path_is_absolute(target)) {
 298                                         target_abs = path_join(*dir, target);
 299                                         if (!target_abs)
 300                                                 return log_oom();
 301
 302                                         free_and_replace(target, target_abs);
 303                                 }
 304
 305                                 /* Get rid of "." and ".." components in target path */
 306                                 r = chase_symlinks(target, lp->root_dir, CHASE_NOFOLLOW | CHASE_NONEXISTENT, &simplified, NULL);
 307                                 if (r < 0) {
 308                                         log_warning_errno(r, "Failed to resolve symlink %s pointing to %s, ignoring: %m",
 309                                                           filename, target);
 310                                         continue;
 311                                 }
 312
 313                                 /* Check if the symlink goes outside of our search path.
 314                                  * If yes, it's a linked unit file or mask, and we don't care about the target name.
 315                                  * Let's just store the link destination directly.
 316                                  * If not, let's verify that it's a good symlink. */
 317                                 char *tail = path_startswith_strv(simplified, lp->search_path);
 318                                 if (tail) {
 319                                         bool self_alias;
 320
 321                                         dst = basename(simplified);
 322                                         self_alias = streq(dst, de->d_name);
 323
 324                                         if (is_path(tail))
 325                                                 log_full(self_alias ? LOG_DEBUG : LOG_WARNING,
 326                                                          "Suspicious symlink %s→%s, treating as alias.",
 327                                                          filename, simplified);
 328
 329                                         r = unit_validate_alias_symlink_and_warn(filename, simplified);
 330                                         if (r < 0)
 331                                                 continue;
 332
 333                                         if (self_alias) {
 334                                                 /* A self-alias that has no effect */
 335                                                 log_debug("%s: self-alias: %s/%s → %s, ignoring.",
 336                                                           __func__, *dir, de->d_name, dst);
 337                                                 continue;
 338                                         }
 339
 340                                         log_debug("%s: alias: %s/%s → %s", __func__, *dir, de->d_name, dst);
 341                                 } else {
 342                                         dst  = simplified;
 343
 344                                         log_debug("%s: linked unit file: %s/%s → %s", __func__, *dir, de->d_name, dst);
 345                                 }
 346
 347                         } else {
 348                                 dst = filename;
 349                                 log_debug("%s: normal unit file: %s", __func__, dst);
 350                         }
 351
 352                         r = hashmap_put_strdup(&ids, de->d_name, dst);
 353                         if (r < 0)
 354                                 return log_warning_errno(r, "Failed to add entry to hashmap (%s→%s): %m",
 355                                                          de->d_name, dst);
 356                 }
 357         }
 358
 359         /* Let's also put the names in the reverse db. */
 360         Iterator it;
 361         const char *dummy, *src;
 362         HASHMAP_FOREACH_KEY(dummy, src, ids, it) {
 363                 const char *dst;
 364
 365                 r = unit_ids_map_get(ids, src, &dst);
 366                 if (r < 0)
 367                         continue;
 368
 369                 if (null_or_empty_path(dst) != 0)
 370                         continue;
 371
 372                 /* Do not treat instance symlinks that point to the template as aliases */
 373                 if (unit_name_is_valid(basename(dst), UNIT_NAME_TEMPLATE) &&
 374                     unit_name_is_valid(src, UNIT_NAME_INSTANCE))
 375                         continue;
 376
 377                 r = string_strv_hashmap_put(&names, basename(dst), src);
 378                 if (r < 0)
 379                         return log_warning_errno(r, "Failed to add entry to hashmap (%s→%s): %m",
 380                                                  basename(dst), src);
 381         }
 382
 383         if (cache_mtime)
 384                 *cache_mtime = mtime;
 385         *ret_unit_ids_map = TAKE_PTR(ids);
 386         *ret_unit_names_map = TAKE_PTR(names);
 387         if (ret_path_cache)
 388                 *ret_path_cache = TAKE_PTR(paths);
 389
 390         return 1;
 391 }
 392
 393 int unit_file_find_fragment(
 394                 Hashmap *unit_ids_map,
 395                 Hashmap *unit_name_map,
 396                 const char *unit_name,
 397                 const char **ret_fragment_path,
 398                 Set **ret_names) {
 399
 400         const char *fragment = NULL;
 401         _cleanup_free_ char *template = NULL, *instance = NULL;
 402         _cleanup_set_free_free_ Set *names = NULL;
 403         char **t, **nnn;
 404         int r, name_type;
 405
 406         /* Finds a fragment path, and returns the set of names:
 407          * if we have …/foo.service and …/foo-alias.service→foo.service,
 408          * and …/foo@.service and …/foo-alias@.service→foo@.service,
 409          * and …/foo@inst.service,
 410          * this should return:
 411          * foo.service → …/foo.service, {foo.service, foo-alias.service},
 412          * foo-alias.service → …/foo.service, {foo.service, foo-alias.service},
 413          * foo@.service → …/foo@.service, {foo@.service, foo-alias@.service},
 414          * foo-alias@.service → …/foo@.service, {foo@.service, foo-alias@.service},
 415          * foo@bar.service → …/foo@.service, {foo@bar.service, foo-alias@bar.service},
 416          * foo-alias@bar.service → …/foo@.service, {foo@bar.service, foo-alias@bar.service},
 417          * foo-alias@inst.service → …/foo@inst.service, {foo@inst.service, foo-alias@inst.service}.
 418          */
 419
 420         name_type = unit_name_to_instance(unit_name, &instance);
 421         if (name_type < 0)
 422                 return name_type;
 423
 424         names = set_new(&string_hash_ops);
 425         if (!names)
 426                 return -ENOMEM;
 427
 428         /* The unit always has its own name if it's not a template. */
 429         if (IN_SET(name_type, UNIT_NAME_PLAIN, UNIT_NAME_INSTANCE)) {
 430                 r = set_put_strdup(names, unit_name);
 431                 if (r < 0)
 432                         return r;
 433         }
 434
 435         /* First try to load fragment under the original name */
 436         r = unit_ids_map_get(unit_ids_map, unit_name, &fragment);
 437         if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO))
 438                 return log_debug_errno(r, "Cannot load unit %s: %m", unit_name);
 439
 440         if (fragment) {
 441                 /* Add any aliases of the original name to the set of names */
 442                 nnn = hashmap_get(unit_name_map, basename(fragment));
 443                 STRV_FOREACH(t, nnn) {
 444                         if (name_type == UNIT_NAME_INSTANCE && unit_name_is_valid(*t, UNIT_NAME_TEMPLATE)) {
 445                                 char *inst;
 446
 447                                 r = unit_name_replace_instance(*t, instance, &inst);
 448                                 if (r < 0)
 449                                         return log_debug_errno(r, "Cannot build instance name %s+%s: %m", *t, instance);
 450
 451                                 if (!streq(unit_name, inst))
 452                                         log_debug("%s: %s has alias %s", __func__, unit_name, inst);
 453
 454                                 log_info("%s: %s+%s → %s", __func__, *t, instance, inst);
 455                                 r = set_consume(names, inst);
 456                         } else {
 457                                 if (!streq(unit_name, *t))
 458                                         log_debug("%s: %s has alias %s", __func__, unit_name, *t);
 459
 460                                 r = set_put_strdup(names, *t);
 461                         }
 462                         if (r < 0)
 463                                 return r;
 464                 }
 465         }
 466
 467         if (!fragment && name_type == UNIT_NAME_INSTANCE) {
 468                 /* Look for a fragment under the template name */
 469
 470                 r = unit_name_template(unit_name, &template);
 471                 if (r < 0)
 472                         return log_error_errno(r, "Failed to determine template name: %m");
 473
 474                 r = unit_ids_map_get(unit_ids_map, template, &fragment);
 475                 if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO))
 476                         return log_debug_errno(r, "Cannot load template %s: %m", template);
 477
 478                 if (fragment) {
 479                         /* Add any aliases of the original name to the set of names */
 480                         nnn = hashmap_get(unit_name_map, basename(fragment));
 481                         STRV_FOREACH(t, nnn) {
 482                                 _cleanup_free_ char *inst = NULL;
 483                                 const char *inst_fragment = NULL;
 484
 485                                 r = unit_name_replace_instance(*t, instance, &inst);
 486                                 if (r < 0)
 487                                         return log_debug_errno(r, "Cannot build instance name %s+%s: %m", template, instance);
 488
 489                                 /* Exclude any aliases that point in some other direction. */
 490                                 r = unit_ids_map_get(unit_ids_map, inst, &inst_fragment);
 491                                 if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO))
 492                                         return log_debug_errno(r, "Cannot find instance fragment %s: %m", inst);
 493
 494                                 if (inst_fragment &&
 495                                     !streq(basename(inst_fragment), basename(fragment))) {
 496                                         log_debug("Instance %s has fragment %s and is not an alias of %s.",
 497                                                   inst, inst_fragment, unit_name);
 498                                         continue;
 499                                 }
 500
 501                                 if (!streq(unit_name, inst))
 502                                         log_debug("%s: %s has alias %s", __func__, unit_name, inst);
 503                                 r = set_consume(names, TAKE_PTR(inst));
 504                                 if (r < 0)
 505                                         return r;
 506                         }
 507                 }
 508         }
 509
 510         *ret_fragment_path = fragment;
 511         *ret_names = TAKE_PTR(names);
 512
 513         // FIXME: if instance, consider any unit names with different template name
 514         return 0;
 515 }
 516
 517 static const char * const rlmap[] = {
 518         "emergency", SPECIAL_EMERGENCY_TARGET,
 519         "-b",        SPECIAL_EMERGENCY_TARGET,
 520         "rescue",    SPECIAL_RESCUE_TARGET,
 521         "single",    SPECIAL_RESCUE_TARGET,
 522         "-s",        SPECIAL_RESCUE_TARGET,
 523         "s",         SPECIAL_RESCUE_TARGET,
 524         "S",         SPECIAL_RESCUE_TARGET,
 525         "1",         SPECIAL_RESCUE_TARGET,
 526         "2",         SPECIAL_MULTI_USER_TARGET,
 527         "3",         SPECIAL_MULTI_USER_TARGET,
 528         "4",         SPECIAL_MULTI_USER_TARGET,
 529         "5",         SPECIAL_GRAPHICAL_TARGET,
 530         NULL
 531 };
 532
 533 static const char * const rlmap_initrd[] = {
 534         "emergency", SPECIAL_EMERGENCY_TARGET,
 535         "rescue",    SPECIAL_RESCUE_TARGET,
 536         NULL
 537 };
 538
 539 const char* runlevel_to_target(const char *word) {
 540         const char * const *rlmap_ptr;
 541         size_t i;
 542
 543         if (!word)
 544                 return NULL;
 545
 546         if (in_initrd()) {
 547                 word = startswith(word, "rd.");
 548                 if (!word)
 549                         return NULL;
 550         }
 551
 552         rlmap_ptr = in_initrd() ? rlmap_initrd : rlmap;
 553
 554         for (i = 0; rlmap_ptr[i]; i += 2)
 555                 if (streq(word, rlmap_ptr[i]))
 556                         return rlmap_ptr[i+1];
 557
 558         return NULL;
 559 }