/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include "sd-id128.h" #include "dirent-util.h" #include "fd-util.h" #include "fs-util.h" #include "macro.h" #include "path-lookup.h" #include "set.h" #include "special.h" #include "stat-util.h" #include "string-util.h" #include "strv.h" #include "unit-file.h" bool unit_type_may_alias(UnitType type) { return IN_SET(type, UNIT_SERVICE, UNIT_SOCKET, UNIT_TARGET, UNIT_DEVICE, UNIT_TIMER, UNIT_PATH); } bool unit_type_may_template(UnitType type) { return IN_SET(type, UNIT_SERVICE, UNIT_SOCKET, UNIT_TARGET, UNIT_TIMER, UNIT_PATH); } int unit_symlink_name_compatible(const char *symlink, const char *target, bool instance_propagation) { _cleanup_free_ char *template = NULL; int r, un_type1, un_type2; un_type1 = unit_name_classify(symlink); /* The straightforward case: the symlink name matches the target and we have a valid unit */ if (streq(symlink, target) && (un_type1 & (UNIT_NAME_PLAIN | UNIT_NAME_INSTANCE))) return 1; r = unit_name_template(symlink, &template); if (r == -EINVAL) return 0; /* Not a template */ if (r < 0) return r; un_type2 = unit_name_classify(target); /* An instance name points to a target that is just the template name */ if (un_type1 == UNIT_NAME_INSTANCE && un_type2 == UNIT_NAME_TEMPLATE && streq(template, target)) return 1; /* foo@.target.requires/bar@.service: instance will be propagated */ if (instance_propagation && un_type1 == UNIT_NAME_TEMPLATE && un_type2 == UNIT_NAME_TEMPLATE && streq(template, target)) return 1; return 0; } int unit_validate_alias_symlink_and_warn(const char *filename, const char *target) { const char *src, *dst; _cleanup_free_ char *src_instance = NULL, *dst_instance = NULL; UnitType src_unit_type, dst_unit_type; int src_name_type, dst_name_type; /* Check if the *alias* symlink is valid. This applies to symlinks like * /etc/systemd/system/dbus.service → dbus-broker.service, but not to .wants or .requires symlinks * and such. Neither does this apply to symlinks which *link* units, i.e. symlinks to outside of the * unit lookup path. * * -EINVAL is returned if the something is wrong with the source filename or the source unit type is * not allowed to symlink, * -EXDEV if the target filename is not a valid unit name or doesn't match the source. */ src = basename(filename); dst = basename(target); /* src checks */ src_name_type = unit_name_to_instance(src, &src_instance); if (src_name_type < 0) return log_notice_errno(src_name_type, "%s: not a valid unit name \"%s\": %m", filename, src); src_unit_type = unit_name_to_type(src); assert(src_unit_type >= 0); /* unit_name_to_instance() checked the suffix already */ if (!unit_type_may_alias(src_unit_type)) return log_notice_errno(SYNTHETIC_ERRNO(EINVAL), "%s: symlinks are not allowed for units of this type, rejecting.", filename); if (src_name_type != UNIT_NAME_PLAIN && !unit_type_may_template(src_unit_type)) return log_notice_errno(SYNTHETIC_ERRNO(EINVAL), "%s: templates not allowed for %s units, rejecting.", filename, unit_type_to_string(src_unit_type)); /* dst checks */ dst_name_type = unit_name_to_instance(dst, &dst_instance); if (dst_name_type < 0) return log_notice_errno(dst_name_type == -EINVAL ? SYNTHETIC_ERRNO(EXDEV) : dst_name_type, "%s points to \"%s\" which is not a valid unit name: %m", filename, dst); if (!(dst_name_type == src_name_type || (src_name_type == UNIT_NAME_INSTANCE && dst_name_type == UNIT_NAME_TEMPLATE))) return log_notice_errno(SYNTHETIC_ERRNO(EXDEV), "%s: symlink target name type \"%s\" does not match source, rejecting.", filename, dst); if (dst_name_type == UNIT_NAME_INSTANCE) { assert(src_instance); assert(dst_instance); if (!streq(src_instance, dst_instance)) return log_notice_errno(SYNTHETIC_ERRNO(EXDEV), "%s: unit symlink target \"%s\" instance name doesn't match, rejecting.", filename, dst); } dst_unit_type = unit_name_to_type(dst); if (dst_unit_type != src_unit_type) return log_notice_errno(SYNTHETIC_ERRNO(EXDEV), "%s: symlink target \"%s\" has incompatible suffix, rejecting.", filename, dst); return 0; } #define FOLLOW_MAX 8 static int unit_ids_map_get( Hashmap *unit_ids_map, const char *unit_name, const char **ret_fragment_path) { /* Resolve recursively until we hit an absolute path, i.e. a non-aliased unit. * * We distinguish the case where unit_name was not found in the hashmap at all, and the case where * some symlink was broken. * * If a symlink target points to an instance name, then we also check for the template. */ const char *id = NULL; int r; for (unsigned n = 0; n < FOLLOW_MAX; n++) { const char *t = hashmap_get(unit_ids_map, id ?: unit_name); if (!t) { _cleanup_free_ char *template = NULL; if (!id) return -ENOENT; r = unit_name_template(id, &template); if (r == -EINVAL) return -ENXIO; /* we failed to find the symlink target */ if (r < 0) return log_error_errno(r, "Failed to determine template name for %s: %m", id); t = hashmap_get(unit_ids_map, template); if (!t) return -ENXIO; /* We successfully switched from instanced name to a template, let's continue */ } if (path_is_absolute(t)) { if (ret_fragment_path) *ret_fragment_path = t; return 0; } id = t; } return -ELOOP; } static bool lookup_paths_mtime_exclude(const LookupPaths *lp, const char *path) { /* Paths that are under our exclusive control. Users shall not alter those directly. */ return streq_ptr(path, lp->generator) || streq_ptr(path, lp->generator_early) || streq_ptr(path, lp->generator_late) || streq_ptr(path, lp->transient) || streq_ptr(path, lp->persistent_control) || streq_ptr(path, lp->runtime_control); } #define HASH_KEY SD_ID128_MAKE(4e,86,1b,e3,39,b3,40,46,98,5d,b8,11,34,8f,c3,c1) bool lookup_paths_timestamp_hash_same(const LookupPaths *lp, uint64_t timestamp_hash, uint64_t *ret_new) { struct siphash state; siphash24_init(&state, HASH_KEY.bytes); char **dir; STRV_FOREACH(dir, (char**) lp->search_path) { struct stat st; if (lookup_paths_mtime_exclude(lp, *dir)) continue; /* Determine the latest lookup path modification time */ if (stat(*dir, &st) < 0) { if (errno == ENOENT) continue; log_debug_errno(errno, "Failed to stat %s, ignoring: %m", *dir); continue; } siphash24_compress_usec_t(timespec_load(&st.st_mtim), &state); } uint64_t updated = siphash24_finalize(&state); if (ret_new) *ret_new = updated; if (updated != timestamp_hash) log_debug("Modification times have changed, need to update cache."); return updated == timestamp_hash; } int unit_file_build_name_map( const LookupPaths *lp, uint64_t *cache_timestamp_hash, Hashmap **unit_ids_map, Hashmap **unit_names_map, Set **path_cache) { /* Build two mappings: any name → main unit (i.e. the end result of symlink resolution), unit name → * all aliases (i.e. the entry for a given key is a a list of all names which point to this key). The * key is included in the value iff we saw a file or symlink with that name. In other words, if we * have a key, but it is not present in the value for itself, there was an alias pointing to it, but * the unit itself is not loadable. * * At the same, build a cache of paths where to find units. The non-const parameters are for input * and output. Existing contents will be freed before the new contents are stored. */ _cleanup_hashmap_free_ Hashmap *ids = NULL, *names = NULL; _cleanup_set_free_free_ Set *paths = NULL; uint64_t timestamp_hash; char **dir; int r; /* Before doing anything, check if the timestamp hash that was passed is still valid. * If yes, do nothing. */ if (cache_timestamp_hash && lookup_paths_timestamp_hash_same(lp, *cache_timestamp_hash, ×tamp_hash)) return 0; /* The timestamp hash is now set based on the mtimes from before when we start reading files. * If anything is modified concurrently, we'll consider the cache outdated. */ if (path_cache) { paths = set_new(&path_hash_ops_free); if (!paths) return log_oom(); } STRV_FOREACH(dir, (char**) lp->search_path) { struct dirent *de; _cleanup_closedir_ DIR *d = NULL; d = opendir(*dir); if (!d) { if (errno != ENOENT) log_warning_errno(errno, "Failed to open \"%s\", ignoring: %m", *dir); continue; } FOREACH_DIRENT_ALL(de, d, log_warning_errno(errno, "Failed to read \"%s\", ignoring: %m", *dir)) { char *filename; _cleanup_free_ char *_filename_free = NULL, *simplified = NULL; const char *suffix, *dst = NULL; bool valid_unit_name; valid_unit_name = unit_name_is_valid(de->d_name, UNIT_NAME_ANY); /* We only care about valid units and dirs with certain suffixes, let's ignore the * rest. */ if (!valid_unit_name && !ENDSWITH_SET(de->d_name, ".wants", ".requires", ".d")) continue; filename = path_join(*dir, de->d_name); if (!filename) return log_oom(); if (paths) { r = set_consume(paths, filename); if (r < 0) return log_oom(); /* We will still use filename below. This is safe because we know the set * holds a reference. */ } else _filename_free = filename; /* Make sure we free the filename. */ if (!valid_unit_name) continue; assert_se(suffix = strrchr(de->d_name, '.')); /* search_path is ordered by priority (highest first). If the name is already mapped * to something (incl. itself), it means that we have already seen it, and we should * ignore it here. */ if (hashmap_contains(ids, de->d_name)) continue; dirent_ensure_type(d, de); if (de->d_type == DT_LNK) { /* We don't explicitly check for alias loops here. unit_ids_map_get() which * limits the number of hops should be used to access the map. */ _cleanup_free_ char *target = NULL; r = readlinkat_malloc(dirfd(d), de->d_name, &target); if (r < 0) { log_warning_errno(r, "Failed to read symlink %s/%s, ignoring: %m", *dir, de->d_name); continue; } const bool is_abs = path_is_absolute(target); if (lp->root_dir || !is_abs) { char *target_abs = path_join(is_abs ? lp->root_dir : *dir, target); if (!target_abs) return log_oom(); free_and_replace(target, target_abs); } /* Get rid of "." and ".." components in target path */ r = chase_symlinks(target, lp->root_dir, CHASE_NOFOLLOW | CHASE_NONEXISTENT, &simplified, NULL); if (r < 0) { log_warning_errno(r, "Failed to resolve symlink %s pointing to %s, ignoring: %m", filename, target); continue; } /* Check if the symlink goes outside of our search path. * If yes, it's a linked unit file or mask, and we don't care about the target name. * Let's just store the link destination directly. * If not, let's verify that it's a good symlink. */ char *tail = path_startswith_strv(simplified, lp->search_path); if (tail) { bool self_alias; dst = basename(simplified); self_alias = streq(dst, de->d_name); if (is_path(tail)) log_full(self_alias ? LOG_DEBUG : LOG_WARNING, "Suspicious symlink %s→%s, treating as alias.", filename, simplified); r = unit_validate_alias_symlink_and_warn(filename, simplified); if (r < 0) continue; if (self_alias) { /* A self-alias that has no effect */ log_debug("%s: self-alias: %s/%s → %s, ignoring.", __func__, *dir, de->d_name, dst); continue; } log_debug("%s: alias: %s/%s → %s", __func__, *dir, de->d_name, dst); } else { dst = simplified; log_debug("%s: linked unit file: %s/%s → %s", __func__, *dir, de->d_name, dst); } } else { dst = filename; log_debug("%s: normal unit file: %s", __func__, dst); } r = hashmap_put_strdup(&ids, de->d_name, dst); if (r < 0) return log_warning_errno(r, "Failed to add entry to hashmap (%s→%s): %m", de->d_name, dst); } } /* Let's also put the names in the reverse db. */ const char *dummy, *src; HASHMAP_FOREACH_KEY(dummy, src, ids) { const char *dst; r = unit_ids_map_get(ids, src, &dst); if (r < 0) continue; if (null_or_empty_path(dst) != 0) continue; /* Do not treat instance symlinks that point to the template as aliases */ if (unit_name_is_valid(basename(dst), UNIT_NAME_TEMPLATE) && unit_name_is_valid(src, UNIT_NAME_INSTANCE)) continue; r = string_strv_hashmap_put(&names, basename(dst), src); if (r < 0) return log_warning_errno(r, "Failed to add entry to hashmap (%s→%s): %m", basename(dst), src); } if (cache_timestamp_hash) *cache_timestamp_hash = timestamp_hash; hashmap_free_and_replace(*unit_ids_map, ids); hashmap_free_and_replace(*unit_names_map, names); if (path_cache) set_free_and_replace(*path_cache, paths); return 1; } int unit_file_find_fragment( Hashmap *unit_ids_map, Hashmap *unit_name_map, const char *unit_name, const char **ret_fragment_path, Set **ret_names) { const char *fragment = NULL; _cleanup_free_ char *template = NULL, *instance = NULL; _cleanup_set_free_free_ Set *names = NULL; char **t, **nnn; int r, name_type; /* Finds a fragment path, and returns the set of names: * if we have …/foo.service and …/foo-alias.service→foo.service, * and …/foo@.service and …/foo-alias@.service→foo@.service, * and …/foo@inst.service, * this should return: * foo.service → …/foo.service, {foo.service, foo-alias.service}, * foo-alias.service → …/foo.service, {foo.service, foo-alias.service}, * foo@.service → …/foo@.service, {foo@.service, foo-alias@.service}, * foo-alias@.service → …/foo@.service, {foo@.service, foo-alias@.service}, * foo@bar.service → …/foo@.service, {foo@bar.service, foo-alias@bar.service}, * foo-alias@bar.service → …/foo@.service, {foo@bar.service, foo-alias@bar.service}, * foo-alias@inst.service → …/foo@inst.service, {foo@inst.service, foo-alias@inst.service}. */ name_type = unit_name_to_instance(unit_name, &instance); if (name_type < 0) return name_type; names = set_new(&string_hash_ops); if (!names) return -ENOMEM; /* The unit always has its own name if it's not a template. */ if (IN_SET(name_type, UNIT_NAME_PLAIN, UNIT_NAME_INSTANCE)) { r = set_put_strdup(&names, unit_name); if (r < 0) return r; } /* First try to load fragment under the original name */ r = unit_ids_map_get(unit_ids_map, unit_name, &fragment); if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO)) return log_debug_errno(r, "Cannot load unit %s: %m", unit_name); if (fragment) { /* Add any aliases of the original name to the set of names */ nnn = hashmap_get(unit_name_map, basename(fragment)); STRV_FOREACH(t, nnn) { if (name_type == UNIT_NAME_INSTANCE && unit_name_is_valid(*t, UNIT_NAME_TEMPLATE)) { char *inst; r = unit_name_replace_instance(*t, instance, &inst); if (r < 0) return log_debug_errno(r, "Cannot build instance name %s+%s: %m", *t, instance); if (!streq(unit_name, inst)) log_debug("%s: %s has alias %s", __func__, unit_name, inst); log_info("%s: %s+%s → %s", __func__, *t, instance, inst); r = set_consume(names, inst); } else { if (!streq(unit_name, *t)) log_debug("%s: %s has alias %s", __func__, unit_name, *t); r = set_put_strdup(&names, *t); } if (r < 0) return r; } } if (!fragment && name_type == UNIT_NAME_INSTANCE) { /* Look for a fragment under the template name */ r = unit_name_template(unit_name, &template); if (r < 0) return log_error_errno(r, "Failed to determine template name: %m"); r = unit_ids_map_get(unit_ids_map, template, &fragment); if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO)) return log_debug_errno(r, "Cannot load template %s: %m", template); if (fragment) { /* Add any aliases of the original name to the set of names */ nnn = hashmap_get(unit_name_map, basename(fragment)); STRV_FOREACH(t, nnn) { _cleanup_free_ char *inst = NULL; const char *inst_fragment = NULL; r = unit_name_replace_instance(*t, instance, &inst); if (r < 0) return log_debug_errno(r, "Cannot build instance name %s+%s: %m", template, instance); /* Exclude any aliases that point in some other direction. */ r = unit_ids_map_get(unit_ids_map, inst, &inst_fragment); if (r < 0 && !IN_SET(r, -ENOENT, -ENXIO)) return log_debug_errno(r, "Cannot find instance fragment %s: %m", inst); if (inst_fragment && !streq(basename(inst_fragment), basename(fragment))) { log_debug("Instance %s has fragment %s and is not an alias of %s.", inst, inst_fragment, unit_name); continue; } if (!streq(unit_name, inst)) log_debug("%s: %s has alias %s", __func__, unit_name, inst); r = set_consume(names, TAKE_PTR(inst)); if (r < 0) return r; } } } *ret_fragment_path = fragment; *ret_names = TAKE_PTR(names); // FIXME: if instance, consider any unit names with different template name return 0; } static const char * const rlmap[] = { "emergency", SPECIAL_EMERGENCY_TARGET, "-b", SPECIAL_EMERGENCY_TARGET, "rescue", SPECIAL_RESCUE_TARGET, "single", SPECIAL_RESCUE_TARGET, "-s", SPECIAL_RESCUE_TARGET, "s", SPECIAL_RESCUE_TARGET, "S", SPECIAL_RESCUE_TARGET, "1", SPECIAL_RESCUE_TARGET, "2", SPECIAL_MULTI_USER_TARGET, "3", SPECIAL_MULTI_USER_TARGET, "4", SPECIAL_MULTI_USER_TARGET, "5", SPECIAL_GRAPHICAL_TARGET, NULL }; static const char * const rlmap_initrd[] = { "emergency", SPECIAL_EMERGENCY_TARGET, "rescue", SPECIAL_RESCUE_TARGET, NULL }; const char* runlevel_to_target(const char *word) { const char * const *rlmap_ptr; size_t i; if (!word) return NULL; if (in_initrd()) { word = startswith(word, "rd."); if (!word) return NULL; } rlmap_ptr = in_initrd() ? rlmap_initrd : rlmap; for (i = 0; rlmap_ptr[i]; i += 2) if (streq(word, rlmap_ptr[i])) return rlmap_ptr[i+1]; return NULL; }