/* SPDX-License-Identifier: LGPL-2.1-or-later */ #include "sd-messages.h" #include "alloc-util.h" #include "conf-files.h" #include "constants.h" #include "dns-domain.h" #include "fd-util.h" #include "fileio.h" #include "hexdecoct.h" #include "nulstr-util.h" #include "parse-util.h" #include "resolved-dns-dnssec.h" #include "resolved-dns-trust-anchor.h" #include "set.h" #include "sort-util.h" #include "string-util.h" #include "strv.h" static const char trust_anchor_dirs[] = CONF_PATHS_NULSTR("dnssec-trust-anchors.d"); /* The second DS RR from https://data.iana.org/root-anchors/root-anchors.xml, retrieved February 2017 */ static const uint8_t root_digest2[] = { 0xE0, 0x6D, 0x44, 0xB8, 0x0B, 0x8F, 0x1D, 0x39, 0xA9, 0x5C, 0x0B, 0x0D, 0x7C, 0x65, 0xD0, 0x84, 0x58, 0xE8, 0x80, 0x40, 0x9B, 0xBC, 0x68, 0x34, 0x57, 0x10, 0x42, 0x37, 0xC7, 0xF8, 0xEC, 0x8D }; static bool dns_trust_anchor_knows_domain_positive(DnsTrustAnchor *d, const char *name) { assert(d); /* Returns true if there's an entry for the specified domain * name in our trust anchor */ return hashmap_contains(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_DNSKEY, name)) || hashmap_contains(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_DS, name)); } static int add_root_ksk( DnsAnswer *answer, DnsResourceKey *key, uint16_t key_tag, uint8_t algorithm, uint8_t digest_type, const void *digest, size_t digest_size) { _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; int r; rr = dns_resource_record_new(key); if (!rr) return -ENOMEM; rr->ds.key_tag = key_tag; rr->ds.algorithm = algorithm; rr->ds.digest_type = digest_type; rr->ds.digest_size = digest_size; rr->ds.digest = memdup(digest, rr->ds.digest_size); if (!rr->ds.digest) return -ENOMEM; r = dns_answer_add(answer, rr, 0, DNS_ANSWER_AUTHENTICATED, NULL); if (r < 0) return r; return 0; } static int dns_trust_anchor_add_builtin_positive(DnsTrustAnchor *d) { _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; int r; assert(d); r = hashmap_ensure_allocated(&d->positive_by_key, &dns_resource_key_hash_ops); if (r < 0) return r; /* Only add the built-in trust anchor if there's neither a DS nor a DNSKEY defined for the root domain. That * way users have an easy way to override the root domain DS/DNSKEY data. */ if (dns_trust_anchor_knows_domain_positive(d, ".")) return 0; key = dns_resource_key_new(DNS_CLASS_IN, DNS_TYPE_DS, ""); if (!key) return -ENOMEM; answer = dns_answer_new(2); if (!answer) return -ENOMEM; /* Add the currently valid RRs from https://data.iana.org/root-anchors/root-anchors.xml */ r = add_root_ksk(answer, key, 20326, DNSSEC_ALGORITHM_RSASHA256, DNSSEC_DIGEST_SHA256, root_digest2, sizeof(root_digest2)); if (r < 0) return r; r = hashmap_put(d->positive_by_key, key, answer); if (r < 0) return r; answer = NULL; return 0; } static int dns_trust_anchor_add_builtin_negative(DnsTrustAnchor *d) { static const char private_domains[] = /* RFC 6761 says that .test is a special domain for * testing and not to be installed in the root zone */ "test\0" /* RFC 6761 says that these reverse IP lookup ranges * are for private addresses, and hence should not * show up in the root zone */ "10.in-addr.arpa\0" "16.172.in-addr.arpa\0" "17.172.in-addr.arpa\0" "18.172.in-addr.arpa\0" "19.172.in-addr.arpa\0" "20.172.in-addr.arpa\0" "21.172.in-addr.arpa\0" "22.172.in-addr.arpa\0" "23.172.in-addr.arpa\0" "24.172.in-addr.arpa\0" "25.172.in-addr.arpa\0" "26.172.in-addr.arpa\0" "27.172.in-addr.arpa\0" "28.172.in-addr.arpa\0" "29.172.in-addr.arpa\0" "30.172.in-addr.arpa\0" "31.172.in-addr.arpa\0" "168.192.in-addr.arpa\0" /* The same, but for IPv6. */ "d.f.ip6.arpa\0" /* RFC 6762 reserves the .local domain for Multicast * DNS, it hence cannot appear in the root zone. (Note * that we by default do not route .local traffic to * DNS anyway, except when a configured search domain * suggests so.) */ "local\0" /* These two are well known, popular private zone * TLDs, that are blocked from delegation, according * to: * http://icannwiki.com/Name_Collision#NGPC_Resolution * * There's also ongoing work on making this official * in an RRC: * https://www.ietf.org/archive/id/draft-chapin-additional-reserved-tlds-02.txt */ "home\0" "corp\0" /* The following four TLDs are suggested for private * zones in RFC 6762, Appendix G, and are hence very * unlikely to be made official TLDs any day soon */ "lan\0" "intranet\0" "internal\0" "private\0" /* Defined by RFC 8375. The most official choice. */ "home.arpa\0"; int r; assert(d); /* Only add the built-in trust anchor if there's no negative * trust anchor defined at all. This enables easy overriding * of negative trust anchors. */ if (set_size(d->negative_by_name) > 0) return 0; r = set_ensure_allocated(&d->negative_by_name, &dns_name_hash_ops); if (r < 0) return r; /* We add a couple of domains as default negative trust * anchors, where it's very unlikely they will be installed in * the root zone. If they exist they must be private, and thus * unsigned. */ NULSTR_FOREACH(name, private_domains) { if (dns_trust_anchor_knows_domain_positive(d, name)) continue; r = set_put_strdup(&d->negative_by_name, name); if (r < 0) return r; } return 0; } static int dns_trust_anchor_load_positive(DnsTrustAnchor *d, const char *path, unsigned line, const char *s) { _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; _cleanup_free_ char *domain = NULL, *class = NULL, *type = NULL; _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; DnsAnswer *old_answer = NULL; const char *p = s; int r; assert(d); assert(line); r = extract_first_word(&p, &domain, NULL, EXTRACT_UNQUOTE); if (r < 0) return log_warning_errno(r, "Unable to parse domain in line %s:%u: %m", path, line); r = dns_name_is_valid(domain); if (r < 0) return log_warning_errno(r, "Failed to check validity of domain name '%s', at line %s:%u, ignoring line: %m", domain, path, line); if (r == 0) { log_warning("Domain name %s is invalid, at line %s:%u, ignoring line.", domain, path, line); return -EINVAL; } r = extract_many_words(&p, NULL, 0, &class, &type, NULL); if (r < 0) return log_warning_errno(r, "Unable to parse class and type in line %s:%u: %m", path, line); if (r != 2) { log_warning("Missing class or type in line %s:%u", path, line); return -EINVAL; } if (!strcaseeq(class, "IN")) { log_warning("RR class %s is not supported, ignoring line %s:%u.", class, path, line); return -EINVAL; } if (strcaseeq(type, "DS")) { _cleanup_free_ char *key_tag = NULL, *algorithm = NULL, *digest_type = NULL; _cleanup_free_ void *dd = NULL; uint16_t kt; int a, dt; size_t l; r = extract_many_words(&p, NULL, 0, &key_tag, &algorithm, &digest_type, NULL); if (r < 0) { log_warning_errno(r, "Failed to parse DS parameters on line %s:%u: %m", path, line); return -EINVAL; } if (r != 3) { log_warning("Missing DS parameters on line %s:%u", path, line); return -EINVAL; } r = safe_atou16(key_tag, &kt); if (r < 0) return log_warning_errno(r, "Failed to parse DS key tag %s on line %s:%u: %m", key_tag, path, line); a = dnssec_algorithm_from_string(algorithm); if (a < 0) { log_warning("Failed to parse DS algorithm %s on line %s:%u", algorithm, path, line); return -EINVAL; } dt = dnssec_digest_from_string(digest_type); if (dt < 0) { log_warning("Failed to parse DS digest type %s on line %s:%u", digest_type, path, line); return -EINVAL; } if (isempty(p)) { log_warning("Missing DS digest on line %s:%u", path, line); return -EINVAL; } r = unhexmem(p, strlen(p), &dd, &l); if (r < 0) { log_warning("Failed to parse DS digest %s on line %s:%u", p, path, line); return -EINVAL; } rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_DS, domain); if (!rr) return log_oom(); rr->ds.key_tag = kt; rr->ds.algorithm = a; rr->ds.digest_type = dt; rr->ds.digest_size = l; rr->ds.digest = TAKE_PTR(dd); } else if (strcaseeq(type, "DNSKEY")) { _cleanup_free_ char *flags = NULL, *protocol = NULL, *algorithm = NULL; _cleanup_free_ void *k = NULL; uint16_t f; size_t l; int a; r = extract_many_words(&p, NULL, 0, &flags, &protocol, &algorithm, NULL); if (r < 0) return log_warning_errno(r, "Failed to parse DNSKEY parameters on line %s:%u: %m", path, line); if (r != 3) { log_warning("Missing DNSKEY parameters on line %s:%u", path, line); return -EINVAL; } if (!streq(protocol, "3")) { log_warning("DNSKEY Protocol is not 3 on line %s:%u", path, line); return -EINVAL; } r = safe_atou16(flags, &f); if (r < 0) return log_warning_errno(r, "Failed to parse DNSKEY flags field %s on line %s:%u", flags, path, line); if ((f & DNSKEY_FLAG_ZONE_KEY) == 0) { log_warning("DNSKEY lacks zone key bit set on line %s:%u", path, line); return -EINVAL; } if ((f & DNSKEY_FLAG_REVOKE)) { log_warning("DNSKEY is already revoked on line %s:%u", path, line); return -EINVAL; } a = dnssec_algorithm_from_string(algorithm); if (a < 0) { log_warning("Failed to parse DNSKEY algorithm %s on line %s:%u", algorithm, path, line); return -EINVAL; } if (isempty(p)) { log_warning("Missing DNSKEY key on line %s:%u", path, line); return -EINVAL; } r = unbase64mem(p, strlen(p), &k, &l); if (r < 0) return log_warning_errno(r, "Failed to parse DNSKEY key data %s on line %s:%u", p, path, line); rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_DNSKEY, domain); if (!rr) return log_oom(); rr->dnskey.flags = f; rr->dnskey.protocol = 3; rr->dnskey.algorithm = a; rr->dnskey.key_size = l; rr->dnskey.key = TAKE_PTR(k); } else { log_warning("RR type %s is not supported, ignoring line %s:%u.", type, path, line); return -EINVAL; } r = hashmap_ensure_allocated(&d->positive_by_key, &dns_resource_key_hash_ops); if (r < 0) return log_oom(); old_answer = hashmap_get(d->positive_by_key, rr->key); answer = dns_answer_ref(old_answer); r = dns_answer_add_extend(&answer, rr, 0, DNS_ANSWER_AUTHENTICATED, NULL); if (r < 0) return log_error_errno(r, "Failed to add trust anchor RR: %m"); r = hashmap_replace(d->positive_by_key, rr->key, answer); if (r < 0) return log_error_errno(r, "Failed to add answer to trust anchor: %m"); old_answer = dns_answer_unref(old_answer); answer = NULL; return 0; } static int dns_trust_anchor_load_negative(DnsTrustAnchor *d, const char *path, unsigned line, const char *s) { _cleanup_free_ char *domain = NULL; const char *p = s; int r; assert(d); assert(line); r = extract_first_word(&p, &domain, NULL, EXTRACT_UNQUOTE); if (r < 0) return log_warning_errno(r, "Unable to parse line %s:%u: %m", path, line); r = dns_name_is_valid(domain); if (r < 0) return log_warning_errno(r, "Failed to check validity of domain name '%s', at line %s:%u, ignoring line: %m", domain, path, line); if (r == 0) { log_warning("Domain name %s is invalid, at line %s:%u, ignoring line.", domain, path, line); return -EINVAL; } if (!isempty(p)) { log_warning("Trailing garbage at line %s:%u, ignoring line.", path, line); return -EINVAL; } r = set_ensure_consume(&d->negative_by_name, &dns_name_hash_ops, TAKE_PTR(domain)); if (r < 0) return log_oom(); return 0; } static int dns_trust_anchor_load_files( DnsTrustAnchor *d, const char *suffix, int (*loader)(DnsTrustAnchor *d, const char *path, unsigned n, const char *line)) { _cleanup_strv_free_ char **files = NULL; int r; assert(d); assert(suffix); assert(loader); r = conf_files_list_nulstr(&files, suffix, NULL, 0, trust_anchor_dirs); if (r < 0) return log_error_errno(r, "Failed to enumerate %s trust anchor files: %m", suffix); STRV_FOREACH(f, files) { _cleanup_fclose_ FILE *g = NULL; unsigned n = 0; g = fopen(*f, "re"); if (!g) { if (errno == ENOENT) continue; log_warning_errno(errno, "Failed to open '%s', ignoring: %m", *f); continue; } for (;;) { _cleanup_free_ char *line = NULL; char *l; r = read_line(g, LONG_LINE_MAX, &line); if (r < 0) { log_warning_errno(r, "Failed to read '%s', ignoring: %m", *f); break; } if (r == 0) break; n++; l = strstrip(line); if (isempty(l)) continue; if (*l == ';') continue; (void) loader(d, *f, n, l); } } return 0; } static int domain_name_cmp(char * const *a, char * const *b) { return dns_name_compare_func(*a, *b); } static int dns_trust_anchor_dump(DnsTrustAnchor *d) { DnsAnswer *a; assert(d); if (hashmap_isempty(d->positive_by_key)) log_info("No positive trust anchors defined."); else { log_info("Positive Trust Anchors:"); HASHMAP_FOREACH(a, d->positive_by_key) { DnsResourceRecord *rr; DNS_ANSWER_FOREACH(rr, a) log_info("%s", dns_resource_record_to_string(rr)); } } if (set_isempty(d->negative_by_name)) log_info("No negative trust anchors defined."); else { _cleanup_free_ char **l = NULL, *j = NULL; l = set_get_strv(d->negative_by_name); if (!l) return log_oom(); typesafe_qsort(l, set_size(d->negative_by_name), domain_name_cmp); j = strv_join(l, " "); if (!j) return log_oom(); log_info("Negative trust anchors: %s", j); } return 0; } int dns_trust_anchor_load(DnsTrustAnchor *d) { int r; assert(d); /* If loading things from disk fails, we don't consider this fatal */ (void) dns_trust_anchor_load_files(d, ".positive", dns_trust_anchor_load_positive); (void) dns_trust_anchor_load_files(d, ".negative", dns_trust_anchor_load_negative); /* However, if the built-in DS fails, then we have a problem. */ r = dns_trust_anchor_add_builtin_positive(d); if (r < 0) return log_error_errno(r, "Failed to add built-in positive trust anchor: %m"); r = dns_trust_anchor_add_builtin_negative(d); if (r < 0) return log_error_errno(r, "Failed to add built-in negative trust anchor: %m"); dns_trust_anchor_dump(d); return 0; } void dns_trust_anchor_flush(DnsTrustAnchor *d) { assert(d); d->positive_by_key = hashmap_free_with_destructor(d->positive_by_key, dns_answer_unref); d->revoked_by_rr = set_free_with_destructor(d->revoked_by_rr, dns_resource_record_unref); d->negative_by_name = set_free_free(d->negative_by_name); } int dns_trust_anchor_lookup_positive(DnsTrustAnchor *d, const DnsResourceKey *key, DnsAnswer **ret) { DnsAnswer *a; assert(d); assert(key); assert(ret); /* We only serve DS and DNSKEY RRs. */ if (!IN_SET(key->type, DNS_TYPE_DS, DNS_TYPE_DNSKEY)) return 0; a = hashmap_get(d->positive_by_key, key); if (!a) return 0; *ret = dns_answer_ref(a); return 1; } int dns_trust_anchor_lookup_negative(DnsTrustAnchor *d, const char *name) { int r; assert(d); assert(name); for (;;) { /* If the domain is listed as-is in the NTA database, then that counts */ if (set_contains(d->negative_by_name, name)) return true; /* If the domain isn't listed as NTA, but is listed as positive trust anchor, then that counts. See RFC * 7646, section 1.1 */ if (hashmap_contains(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_DS, name))) return false; if (hashmap_contains(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(DNS_CLASS_IN, DNS_TYPE_KEY, name))) return false; /* And now, let's look at the parent, and check that too */ r = dns_name_parent(&name); if (r < 0) return r; if (r == 0) break; } return false; } static int dns_trust_anchor_revoked_put(DnsTrustAnchor *d, DnsResourceRecord *rr) { int r; assert(d); r = set_ensure_put(&d->revoked_by_rr, &dns_resource_record_hash_ops, rr); if (r < 0) return r; if (r > 0) dns_resource_record_ref(rr); return r; } static int dns_trust_anchor_remove_revoked(DnsTrustAnchor *d, DnsResourceRecord *rr) { _cleanup_(dns_answer_unrefp) DnsAnswer *new_answer = NULL; DnsAnswer *old_answer; DnsAnswerItem *item; int r; /* Remember that this is a revoked trust anchor RR */ r = dns_trust_anchor_revoked_put(d, rr); if (r < 0) return r; /* Remove this from the positive trust anchor */ old_answer = hashmap_get(d->positive_by_key, rr->key); if (!old_answer) return 0; new_answer = dns_answer_ref(old_answer); r = dns_answer_remove_by_rr(&new_answer, rr); if (r <= 0) return r; /* We found the key! Warn the user */ log_struct(LOG_WARNING, "MESSAGE_ID=" SD_MESSAGE_DNSSEC_TRUST_ANCHOR_REVOKED_STR, LOG_MESSAGE("DNSSEC trust anchor %s has been revoked.\n" "Please update the trust anchor, or upgrade your operating system.", strna(dns_resource_record_to_string(rr))), "TRUST_ANCHOR=%s", dns_resource_record_to_string(rr)); if (dns_answer_size(new_answer) <= 0) { assert_se(hashmap_remove(d->positive_by_key, rr->key) == old_answer); dns_answer_unref(old_answer); return 1; } item = ordered_set_first(new_answer->items); r = hashmap_replace(d->positive_by_key, item->rr->key, new_answer); if (r < 0) return r; TAKE_PTR(new_answer); dns_answer_unref(old_answer); return 1; } static int dns_trust_anchor_check_revoked_one(DnsTrustAnchor *d, DnsResourceRecord *revoked_dnskey) { DnsAnswer *a; int r; assert(d); assert(revoked_dnskey); assert(revoked_dnskey->key->type == DNS_TYPE_DNSKEY); assert(revoked_dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE); a = hashmap_get(d->positive_by_key, revoked_dnskey->key); if (a) { DnsResourceRecord *anchor; /* First, look for the precise DNSKEY in our trust anchor database */ DNS_ANSWER_FOREACH(anchor, a) { if (anchor->dnskey.protocol != revoked_dnskey->dnskey.protocol) continue; if (anchor->dnskey.algorithm != revoked_dnskey->dnskey.algorithm) continue; if (anchor->dnskey.key_size != revoked_dnskey->dnskey.key_size) continue; /* Note that we allow the REVOKE bit to be * different! It will be set in the revoked * key, but unset in our version of it */ if (((anchor->dnskey.flags ^ revoked_dnskey->dnskey.flags) | DNSKEY_FLAG_REVOKE) != DNSKEY_FLAG_REVOKE) continue; if (memcmp(anchor->dnskey.key, revoked_dnskey->dnskey.key, anchor->dnskey.key_size) != 0) continue; dns_trust_anchor_remove_revoked(d, anchor); break; } } a = hashmap_get(d->positive_by_key, &DNS_RESOURCE_KEY_CONST(revoked_dnskey->key->class, DNS_TYPE_DS, dns_resource_key_name(revoked_dnskey->key))); if (a) { DnsResourceRecord *anchor; /* Second, look for DS RRs matching this DNSKEY in our trust anchor database */ DNS_ANSWER_FOREACH(anchor, a) { /* We set mask_revoke to true here, since our * DS fingerprint will be the one of the * unrevoked DNSKEY, but the one we got passed * here has the bit set. */ r = dnssec_verify_dnskey_by_ds(revoked_dnskey, anchor, true); if (r < 0) return r; if (r == 0) continue; dns_trust_anchor_remove_revoked(d, anchor); break; } } return 0; } int dns_trust_anchor_check_revoked(DnsTrustAnchor *d, DnsResourceRecord *dnskey, DnsAnswer *rrs) { DnsResourceRecord *rrsig; int r; assert(d); assert(dnskey); /* Looks if "dnskey" is a self-signed RR that has been revoked * and matches one of our trust anchor entries. If so, removes * it from the trust anchor and returns > 0. */ if (dnskey->key->type != DNS_TYPE_DNSKEY) return 0; /* Is this DNSKEY revoked? */ if ((dnskey->dnskey.flags & DNSKEY_FLAG_REVOKE) == 0) return 0; /* Could this be interesting to us at all? If not, * there's no point in looking for and verifying a * self-signed RRSIG. */ if (!dns_trust_anchor_knows_domain_positive(d, dns_resource_key_name(dnskey->key))) return 0; /* Look for a self-signed RRSIG in the other rrs belonging to this DNSKEY */ DNS_ANSWER_FOREACH(rrsig, rrs) { DnssecResult result; if (rrsig->key->type != DNS_TYPE_RRSIG) continue; r = dnssec_rrsig_match_dnskey(rrsig, dnskey, true); if (r < 0) return r; if (r == 0) continue; r = dnssec_verify_rrset(rrs, dnskey->key, rrsig, dnskey, USEC_INFINITY, &result); if (r < 0) return r; if (result != DNSSEC_VALIDATED) continue; /* Bingo! This is a revoked self-signed DNSKEY. Let's * see if this precise one exists in our trust anchor * database, too. */ r = dns_trust_anchor_check_revoked_one(d, dnskey); if (r < 0) return r; return 1; } return 0; } int dns_trust_anchor_is_revoked(DnsTrustAnchor *d, DnsResourceRecord *rr) { assert(d); if (!IN_SET(rr->key->type, DNS_TYPE_DS, DNS_TYPE_DNSKEY)) return 0; return set_contains(d->revoked_by_rr, rr); }