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_symlink_name_compatible(const char *symlink, const char *target, bool instance_propagation) {
  35         _cleanup_free_ char *template = NULL;
  36         int r, un_type1, un_type2;
  37
  38         un_type1 = unit_name_classify(symlink);
  39
  40         /* The straightforward case: the symlink name matches the target and we have a valid unit */
  41         if (streq(symlink, target) &&
  42             (un_type1 & (UNIT_NAME_PLAIN | UNIT_NAME_INSTANCE)))
  43                 return 1;
  44
  45         r = unit_name_template(symlink, &template);
  46         if (r == -EINVAL)
  47                 return 0; /* Not a template */
  48         if (r < 0)
  49                 return r;
  50
  51         un_type2 = unit_name_classify(target);
  52
  53         /* An instance name points to a target that is just the template name */
  54         if (un_type1 == UNIT_NAME_INSTANCE &&
  55             un_type2 == UNIT_NAME_TEMPLATE &&
  56             streq(template, target))
  57                 return 1;
  58
  59         /* foo@.target.requires/bar@.service: instance will be propagated */
  60         if (instance_propagation &&
  61             un_type1 == UNIT_NAME_TEMPLATE &&
  62             un_type2 == UNIT_NAME_TEMPLATE &&
  63             streq(template, target))
  64                 return 1;
  65
  66         return 0;
  67 }
  68
  69 int unit_validate_alias_symlink_and_warn(const char *filename, const char *target) {
  70         const char *src, *dst;
  71         _cleanup_free_ char *src_instance = NULL, *dst_instance = NULL;
  72         UnitType src_unit_type, dst_unit_type;
  73         int src_name_type, dst_name_type;
  74
  75         /* Check if the *alias* symlink is valid. This applies to symlinks like
  76          * /etc/systemd/system/dbus.service → dbus-broker.service, but not to .wants or .requires symlinks
  77          * and such. Neither does this apply to symlinks which *link* units, i.e. symlinks to outside of the
  78          * unit lookup path.
  79          *
  80          * -EINVAL is returned if the something is wrong with the source filename or the source unit type is
  81          *         not allowed to symlink,
  82          * -EXDEV if the target filename is not a valid unit name or doesn't match the source.
  83          */
  84
  85         src = basename(filename);
  86         dst = basename(target);
  87
  88         /* src checks */
  89
  90         src_name_type = unit_name_to_instance(src, &src_instance);
  91         if (src_name_type < 0)
  92                 return log_notice_errno(src_name_type,
  93                                         "%s: not a valid unit name \"%s\": %m", filename, src);
  94
  95         src_unit_type = unit_name_to_type(src);
  96         assert(src_unit_type >= 0); /* unit_name_to_instance() checked the suffix already */
  97
  98         if (!unit_type_may_alias(src_unit_type))
  99                 return log_notice_errno(SYNTHETIC_ERRNO(EINVAL),
 100                                         "%s: symlinks are not allowed for units of this type, rejecting.",
 101                                         filename);
 102
 103         if (src_name_type != UNIT_NAME_PLAIN &&
 104             !unit_type_may_template(src_unit_type))
 105                 return log_notice_errno(SYNTHETIC_ERRNO(EINVAL),
 106                                         "%s: templates not allowed for %s units, rejecting.",
 107                                         filename, unit_type_to_string(src_unit_type));
 108
 109         /* dst checks */
 110
 111         dst_name_type = unit_name_to_instance(dst, &dst_instance);
 112         if (dst_name_type < 0)
 113                 return log_notice_errno(dst_name_type == -EINVAL ? SYNTHETIC_ERRNO(EXDEV) : dst_name_type,
 114                                         "%s points to \"%s\" which is not a valid unit name: %m",
 115                                         filename, dst);
 116
 117         if (!(dst_name_type == src_name_type ||
 118               (src_name_type == UNIT_NAME_INSTANCE && dst_name_type == UNIT_NAME_TEMPLATE)))
 119                 return log_notice_errno(SYNTHETIC_ERRNO(EXDEV),
 120                                         "%s: symlink target name type \"%s\" does not match source, rejecting.",
 121                                         filename, dst);
 122
 123         if (dst_name_type == UNIT_NAME_INSTANCE) {
 124                 assert(src_instance);
 125                 assert(dst_instance);
 126                 if (!streq(src_instance, dst_instance))
 127                         return log_notice_errno(SYNTHETIC_ERRNO(EXDEV),
 128                                                 "%s: unit symlink target \"%s\" instance name doesn't match, rejecting.",
 129                                                 filename, dst);
 130         }
 131
 132         dst_unit_type = unit_name_to_type(dst);
 133         if (dst_unit_type != src_unit_type)
 134                 return log_notice_errno(SYNTHETIC_ERRNO(EXDEV),
 135                                         "%s: symlink target \"%s\" has incompatible suffix, rejecting.",
 136                                         filename, dst);
 137
 138         return 0;
 139 }
 140
 141 #define FOLLOW_MAX 8
 142
 143 static int unit_ids_map_get(
 144                 Hashmap *unit_ids_map,
 145                 const char *unit_name,
 146                 const char **ret_fragment_path) {
 147
 148         /* Resolve recursively until we hit an absolute path, i.e. a non-aliased unit.
 149          *
 150          * We distinguish the case where unit_name was not found in the hashmap at all, and the case where
 151          * some symlink was broken.
 152          *
 153          * If a symlink target points to an instance name, then we also check for the template. */
 154
 155         const char *id = NULL;
 156         int r;
 157
 158         for (unsigned n = 0; n < FOLLOW_MAX; n++) {
 159                 const char *t = hashmap_get(unit_ids_map, id ?: unit_name);
 160                 if (!t) {
 161                         _cleanup_free_ char *template = NULL;
 162
 163                         if (!id)
 164                                 return -ENOENT;
 165
 166                         r = unit_name_template(id, &template);
 167                         if (r == -EINVAL)
 168                                 return -ENXIO; /* we failed to find the symlink target */
 169                         if (r < 0)
 170                                 return log_error_errno(r, "Failed to determine template name for %s: %m", id);
 171
 172                         t = hashmap_get(unit_ids_map, template);
 173                         if (!t)
 174                                 return -ENXIO;
 175
 176                         /* We successfully switched from instanced name to a template, let's continue */
 177                 }
 178
 179                 if (path_is_absolute(t)) {
 180                         if (ret_fragment_path)
 181                                 *ret_fragment_path = t;
 182                         return 0;
 183                 }
 184
 185                 id = t;
 186         }
 187
 188         return -ELOOP;
 189 }
 190
 191 static bool lookup_paths_mtime_exclude(const LookupPaths *lp, const char *path) {
 192         /* Paths that are under our exclusive control. Users shall not alter those directly. */
 193
 194         return streq_ptr(path, lp->generator) ||
 195                streq_ptr(path, lp->generator_early) ||
 196                streq_ptr(path, lp->generator_late) ||
 197                streq_ptr(path, lp->transient) ||
 198                streq_ptr(path, lp->persistent_control) ||
 199                streq_ptr(path, lp->runtime_control);
 200 }
 201
 202 bool lookup_paths_mtime_good(const LookupPaths *lp, usec_t mtime) {
 203         char **dir;
 204
 205         STRV_FOREACH(dir, (char**) lp->search_path) {
 206                 struct stat st;
 207
 208                 if (lookup_paths_mtime_exclude(lp, *dir))
 209                         continue;
 210
 211                 /* Determine the latest lookup path modification time */
 212                 if (stat(*dir, &st) < 0) {
 213                         if (errno == ENOENT)
 214                                 continue;
 215
 216                         log_debug_errno(errno, "Failed to stat %s, ignoring: %m", *dir);
 217                         continue;
 218                 }
 219
 220                 if (timespec_load(&st.st_mtim) > mtime) {
 221                         log_debug_errno(errno, "Unit dir %s has changed, need to update cache.", *dir);
 222                         return false;
 223                 }
 224         }
 225
 226         return true;
 227 }
 228
 229 int unit_file_build_name_map(
 230                 const LookupPaths *lp,
 231                 usec_t *cache_mtime,
 232                 Hashmap **unit_ids_map,
 233                 Hashmap **unit_names_map,
 234                 Set **path_cache) {
 235
 236         /* Build two mappings: any name → main unit (i.e. the end result of symlink resolution), unit name →
 237          * all aliases (i.e. the entry for a given key is a a list of all names which point to this key). The
 238          * key is included in the value iff we saw a file or symlink with that name. In other words, if we
 239          * have a key, but it is not present in the value for itself, there was an alias pointing to it, but
 240          * the unit itself is not loadable.
 241          *
 242          * At the same, build a cache of paths where to find units. The non-const parameters are for input
 243          * and output. Existing contents will be freed before the new contents are stored.
 244          */
 245
 246         _cleanup_hashmap_free_ Hashmap *ids = NULL, *names = NULL;
 247         _cleanup_set_free_free_ Set *paths = NULL;
 248         char **dir;
 249         int r;
 250         usec_t mtime = 0;
 251
 252         /* Before doing anything, check if the mtime that was passed is still valid. If
 253          * yes, do nothing. If *cache_time == 0, always build the cache. */
 254         if (cache_mtime && *cache_mtime > 0 && lookup_paths_mtime_good(lp, *cache_mtime))
 255                 return 0;
 256
 257         if (path_cache) {
 258                 paths = set_new(&path_hash_ops_free);
 259                 if (!paths)
 260                         return log_oom();
 261         }
 262
 263         STRV_FOREACH(dir, (char**) lp->search_path) {
 264                 struct dirent *de;
 265                 _cleanup_closedir_ DIR *d = NULL;
 266                 struct stat st;
 267
 268                 d = opendir(*dir);
 269                 if (!d) {
 270                         if (errno != ENOENT)
 271                                 log_warning_errno(errno, "Failed to open \"%s\", ignoring: %m", *dir);
 272                         continue;
 273                 }
 274
 275                 /* Determine the latest lookup path modification time */
 276                 if (fstat(dirfd(d), &st) < 0)
 277                         return log_error_errno(errno, "Failed to fstat %s: %m", *dir);
 278
 279                 if (!lookup_paths_mtime_exclude(lp, *dir))
 280                         mtime = MAX(mtime, timespec_load(&st.st_mtim));
 281
 282                 FOREACH_DIRENT_ALL(de, d, log_warning_errno(errno, "Failed to read \"%s\", ignoring: %m", *dir)) {
 283                         char *filename;
 284                         _cleanup_free_ char *_filename_free = NULL, *simplified = NULL;
 285                         const char *suffix, *dst = NULL;
 286                         bool valid_unit_name;
 287
 288                         valid_unit_name = unit_name_is_valid(de->d_name, UNIT_NAME_ANY);
 289
 290                         /* We only care about valid units and dirs with certain suffixes, let's ignore the
 291                          * rest. */
 292                         if (!valid_unit_name &&
 293                             !ENDSWITH_SET(de->d_name, ".wants", ".requires", ".d"))
 294                                 continue;
 295
 296                         filename = path_join(*dir, de->d_name);
 297                         if (!filename)
 298                                 return log_oom();
 299
 300                         if (paths) {
 301                                 r = set_consume(paths, filename);
 302                                 if (r < 0)
 303                                         return log_oom();
 304                                 /* We will still use filename below. This is safe because we know the set
 305                                  * holds a reference. */
 306                         } else
 307                                 _filename_free = filename; /* Make sure we free the filename. */
 308
 309                         if (!valid_unit_name)
 310                                 continue;
 311                         assert_se(suffix = strrchr(de->d_name, '.'));
 312
 313                         /* search_path is ordered by priority (highest first). If the name is already mapped
 314                          * to something (incl. itself), it means that we have already seen it, and we should
 315                          * ignore it here. */
 316                         if (hashmap_contains(ids, de->d_name))
 317                                 continue;
 318
 319                         dirent_ensure_type(d, de);
 320                         if (de->d_type == DT_LNK) {
 321                                 /* We don't explicitly check for alias loops here. unit_ids_map_get() which
 322                                  * limits the number of hops should be used to access the map. */
 323
 324                                 _cleanup_free_ char *target = NULL;
 325
 326                                 r = readlinkat_malloc(dirfd(d), de->d_name, &target);
 327                                 if (r < 0) {
 328                                         log_warning_errno(r, "Failed to read symlink %s/%s, ignoring: %m",
 329                                                           *dir, de->d_name);
 330                                         continue;
 331                                 }
 332
 333                                 const bool is_abs = path_is_absolute(target);
 334                                 if (lp->root_dir || !is_abs) {
 335                                         char *target_abs = path_join(is_abs ? lp->root_dir : *dir, target);
 336                                         if (!target_abs)
 337                                                 return log_oom();
 338
 339                                         free_and_replace(target, target_abs);
 340                                 }
 341
 342                                 /* Get rid of "." and ".." components in target path */
 343                                 r = chase_symlinks(target, lp->root_dir, CHASE_NOFOLLOW | CHASE_NONEXISTENT, &simplified, NULL);
 344                                 if (r < 0) {
 345                                         log_warning_errno(r, "Failed to resolve symlink %s pointing to %s, ignoring: %m",
 346                                                           filename, target);
 347                                         continue;
 348                                 }
 349
 350                                 /* Check if the symlink goes outside of our search path.
 351                                  * If yes, it's a linked unit file or mask, and we don't care about the target name.
 352                                  * Let's just store the link destination directly.
 353                                  * If not, let's verify that it's a good symlink. */
 354                                 char *tail = path_startswith_strv(simplified, lp->search_path);
 355                                 if (tail) {
 356                                         bool self_alias;
 357
 358                                         dst = basename(simplified);
 359                                         self_alias = streq(dst, de->d_name);
 360
 361                                         if (is_path(tail))
 362                                                 log_full(self_alias ? LOG_DEBUG : LOG_WARNING,
 363                                                          "Suspicious symlink %s→%s, treating as alias.",
 364                                                          filename, simplified);
 365
 366                                         r = unit_validate_alias_symlink_and_warn(filename, simplified);
 367                                         if (r < 0)
 368                                                 continue;
 369
 370                                         if (self_alias) {
 371                                                 /* A self-alias that has no effect */
 372                                                 log_debug("%s: self-alias: %s/%s → %s, ignoring.",
 373                                                           __func__, *dir, de->d_name, dst);
 374                                                 continue;
 375                                         }
 376
 377                                         log_debug("%s: alias: %s/%s → %s", __func__, *dir, de->d_name, dst);
 378                                 } else {
 379                                         dst  = simplified;
 380
 381                                         log_debug("%s: linked unit file: %s/%s → %s", __func__, *dir, de->d_name, dst);
 382                                 }
 383
 384                         } else {
 385                                 dst = filename;
 386                                 log_debug("%s: normal unit file: %s", __func__, dst);
 387                         }
 388
 389                         r = hashmap_put_strdup(&ids, de->d_name, dst);
 390                         if (r < 0)
 391                                 return log_warning_errno(r, "Failed to add entry to hashmap (%s→%s): %m",
 392                                                          de->d_name, dst);
 393                 }
 394         }
 395
 396         /* Let's also put the names in the reverse db. */
 397         Iterator it;
 398         const char *dummy, *src;
 399         HASHMAP_FOREACH_KEY(dummy, src, ids, it) {
 400                 const char *dst;
 401
 402                 r = unit_ids_map_get(ids, src, &dst);
 403                 if (r < 0)
 404                         continue;
 405
 406                 if (null_or_empty_path(dst) != 0)
 407                         continue;
 408
 409                 /* Do not treat instance symlinks that point to the template as aliases */
 410                 if (unit_name_is_valid(basename(dst), UNIT_NAME_TEMPLATE) &&
 411                     unit_name_is_valid(src, UNIT_NAME_INSTANCE))
 412                         continue;
 413
 414                 r = string_strv_hashmap_put(&names, basename(dst), src);
 415                 if (r < 0)
 416                         return log_warning_errno(r, "Failed to add entry to hashmap (%s→%s): %m",
 417                                                  basename(dst), src);
 418         }
 419
 420         if (cache_mtime)
 421                 *cache_mtime = mtime;
 422
 423         hashmap_free_and_replace(*unit_ids_map, ids);
 424         hashmap_free_and_replace(*unit_names_map, names);
 425         if (path_cache)
 426                 set_free_and_replace(*path_cache, paths);
 427
 428         return 1;
 429 }
 430
 431 int unit_file_find_fragment(
 432                 Hashmap *unit_ids_map,
 433                 Hashmap *unit_name_map,
 434                 const char *unit_name,
 435                 const char **ret_fragment_path,
 436                 Set **ret_names) {
 437
 438         const char *fragment = NULL;
 439         _cleanup_free_ char *template = NULL, *instance = NULL;
 440         _cleanup_set_free_free_ Set *names = NULL;
 441         char **t, **nnn;
 442         int r, name_type;
 443
 444         /* Finds a fragment path, and returns the set of names:
 445          * if we have …/foo.service and …/foo-alias.service→foo.service,
 446          * and …/foo@.service and …/foo-alias@.service→foo@.service,
 447          * and …/foo@inst.service,
 448          * this should return:
 449          * foo.service → …/foo.service, {foo.service, foo-alias.service},
 450          * foo-alias.service → …/foo.service, {foo.service, foo-alias.service},
 451          * foo@.service → …/foo@.service, {foo@.service, foo-alias@.service},
 452          * foo-alias@.service → …/foo@.service, {foo@.service, foo-alias@.service},
 453          * foo@bar.service → …/foo@.service, {foo@bar.service, foo-alias@bar.service},
 454          * foo-alias@bar.service → …/foo@.service, {foo@bar.service, foo-alias@bar.service},
 455          * foo-alias@inst.service → …/foo@inst.service, {foo@inst.service, foo-alias@inst.service}.
 456          */
 457
 458         name_type = unit_name_to_instance(unit_name, &instance);
 459         if (name_type < 0)
 460                 return name_type;
 461
 462         names = set_new(&string_hash_ops);
 463         if (!names)
 464                 return -ENOMEM;
 465
 466         /* The unit always has its own name if it's not a template. */
 467         if (IN_SET(name_type, UNIT_NAME_PLAIN, UNIT_NAME_INSTANCE)) {
 468                 r = set_put_strdup(&names, unit_name);
 469                 if (r < 0)
 470                         return r;
 471         }
 472
 473         /* First try to load fragment under the original name */
 474         r = unit_ids_map_get(unit_ids_map, unit_name, &fragment);
 475         if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO))
 476                 return log_debug_errno(r, "Cannot load unit %s: %m", unit_name);
 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                         if (name_type == UNIT_NAME_INSTANCE && unit_name_is_valid(*t, UNIT_NAME_TEMPLATE)) {
 483                                 char *inst;
 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", *t, instance);
 488
 489                                 if (!streq(unit_name, inst))
 490                                         log_debug("%s: %s has alias %s", __func__, unit_name, inst);
 491
 492                                 log_info("%s: %s+%s → %s", __func__, *t, instance, inst);
 493                                 r = set_consume(names, inst);
 494                         } else {
 495                                 if (!streq(unit_name, *t))
 496                                         log_debug("%s: %s has alias %s", __func__, unit_name, *t);
 497
 498                                 r = set_put_strdup(&names, *t);
 499                         }
 500                         if (r < 0)
 501                                 return r;
 502                 }
 503         }
 504
 505         if (!fragment && name_type == UNIT_NAME_INSTANCE) {
 506                 /* Look for a fragment under the template name */
 507
 508                 r = unit_name_template(unit_name, &template);
 509                 if (r < 0)
 510                         return log_error_errno(r, "Failed to determine template name: %m");
 511
 512                 r = unit_ids_map_get(unit_ids_map, template, &fragment);
 513                 if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO))
 514                         return log_debug_errno(r, "Cannot load template %s: %m", template);
 515
 516                 if (fragment) {
 517                         /* Add any aliases of the original name to the set of names */
 518                         nnn = hashmap_get(unit_name_map, basename(fragment));
 519                         STRV_FOREACH(t, nnn) {
 520                                 _cleanup_free_ char *inst = NULL;
 521                                 const char *inst_fragment = NULL;
 522
 523                                 r = unit_name_replace_instance(*t, instance, &inst);
 524                                 if (r < 0)
 525                                         return log_debug_errno(r, "Cannot build instance name %s+%s: %m", template, instance);
 526
 527                                 /* Exclude any aliases that point in some other direction. */
 528                                 r = unit_ids_map_get(unit_ids_map, inst, &inst_fragment);
 529                                 if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO))
 530                                         return log_debug_errno(r, "Cannot find instance fragment %s: %m", inst);
 531
 532                                 if (inst_fragment &&
 533                                     !streq(basename(inst_fragment), basename(fragment))) {
 534                                         log_debug("Instance %s has fragment %s and is not an alias of %s.",
 535                                                   inst, inst_fragment, unit_name);
 536                                         continue;
 537                                 }
 538
 539                                 if (!streq(unit_name, inst))
 540                                         log_debug("%s: %s has alias %s", __func__, unit_name, inst);
 541                                 r = set_consume(names, TAKE_PTR(inst));
 542                                 if (r < 0)
 543                                         return r;
 544                         }
 545                 }
 546         }
 547
 548         *ret_fragment_path = fragment;
 549         *ret_names = TAKE_PTR(names);
 550
 551         // FIXME: if instance, consider any unit names with different template name
 552         return 0;
 553 }
 554
 555 static const char * const rlmap[] = {
 556         "emergency", SPECIAL_EMERGENCY_TARGET,
 557         "-b",        SPECIAL_EMERGENCY_TARGET,
 558         "rescue",    SPECIAL_RESCUE_TARGET,
 559         "single",    SPECIAL_RESCUE_TARGET,
 560         "-s",        SPECIAL_RESCUE_TARGET,
 561         "s",         SPECIAL_RESCUE_TARGET,
 562         "S",         SPECIAL_RESCUE_TARGET,
 563         "1",         SPECIAL_RESCUE_TARGET,
 564         "2",         SPECIAL_MULTI_USER_TARGET,
 565         "3",         SPECIAL_MULTI_USER_TARGET,
 566         "4",         SPECIAL_MULTI_USER_TARGET,
 567         "5",         SPECIAL_GRAPHICAL_TARGET,
 568         NULL
 569 };
 570
 571 static const char * const rlmap_initrd[] = {
 572         "emergency", SPECIAL_EMERGENCY_TARGET,
 573         "rescue",    SPECIAL_RESCUE_TARGET,
 574         NULL
 575 };
 576
 577 const char* runlevel_to_target(const char *word) {
 578         const char * const *rlmap_ptr;
 579         size_t i;
 580
 581         if (!word)
 582                 return NULL;
 583
 584         if (in_initrd()) {
 585                 word = startswith(word, "rd.");
 586                 if (!word)
 587                         return NULL;
 588         }
 589
 590         rlmap_ptr = in_initrd() ? rlmap_initrd : rlmap;
 591
 592         for (i = 0; rlmap_ptr[i]; i += 2)
 593                 if (streq(word, rlmap_ptr[i]))
 594                         return rlmap_ptr[i+1];
 595
 596         return NULL;
 597 }