diff options
Diffstat (limited to 'src/resolve/resolved-dns-dnssec.c')
| -rw-r--r-- | src/resolve/resolved-dns-dnssec.c | 702 |
1 files changed, 575 insertions, 127 deletions
diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c index 43fcbe1460..1f48f588ce 100644 --- a/src/resolve/resolved-dns-dnssec.c +++ b/src/resolve/resolved-dns-dnssec.c @@ -35,17 +35,12 @@ * * TODO: * - * - wildcard zones compatibility (NSEC/NSEC3 wildcard check is missing) - * - multi-label zone compatibility - * - cname/dname compatibility - * - nxdomain on qname * - bus calls to override DNSEC setting per interface * - log all DNSSEC downgrades + * - log all RRs that failed validation * - enable by default - * - * - RFC 4035, Section 5.3.4 (When receiving a positive wildcard reply, use NSEC to ensure it actually really applies) - * - RFC 6840, Section 4.1 (ensure we don't get fed a glue NSEC from the parent zone) - * - RFC 6840, Section 4.3 (check for CNAME on NSEC too) + * - Allow clients to request DNSSEC even if DNSSEC is off + * - make sure when getting an NXDOMAIN response through CNAME, we still process the first CNAMEs in the packet * */ #define VERIFY_RRS_MAX 256 @@ -430,6 +425,57 @@ static void md_add_uint32(gcry_md_hd_t md, uint32_t v) { gcry_md_write(md, &v, sizeof(v)); } +static int dnssec_rrsig_prepare(DnsResourceRecord *rrsig) { + int n_key_labels, n_signer_labels; + const char *name; + int r; + + /* Checks whether the specified RRSIG RR is somewhat valid, and initializes the .n_skip_labels_source and + * .n_skip_labels_signer fields so that we can use them later on. */ + + assert(rrsig); + assert(rrsig->key->type == DNS_TYPE_RRSIG); + + /* Check if this RRSIG RR is already prepared */ + if (rrsig->n_skip_labels_source != (unsigned) -1) + return 0; + + if (rrsig->rrsig.inception > rrsig->rrsig.expiration) + return -EINVAL; + + name = DNS_RESOURCE_KEY_NAME(rrsig->key); + + n_key_labels = dns_name_count_labels(name); + if (n_key_labels < 0) + return n_key_labels; + if (rrsig->rrsig.labels > n_key_labels) + return -EINVAL; + + n_signer_labels = dns_name_count_labels(rrsig->rrsig.signer); + if (n_signer_labels < 0) + return n_signer_labels; + if (n_signer_labels > rrsig->rrsig.labels) + return -EINVAL; + + r = dns_name_skip(name, n_key_labels - n_signer_labels, &name); + if (r < 0) + return r; + if (r == 0) + return -EINVAL; + + /* Check if the signer is really a suffix of us */ + r = dns_name_equal(name, rrsig->rrsig.signer); + if (r < 0) + return r; + if (r == 0) + return -EINVAL; + + rrsig->n_skip_labels_source = n_key_labels - rrsig->rrsig.labels; + rrsig->n_skip_labels_signer = n_key_labels - n_signer_labels; + + return 0; +} + static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t realtime) { usec_t expiration, inception, skew; @@ -442,8 +488,9 @@ static int dnssec_rrsig_expired(DnsResourceRecord *rrsig, usec_t realtime) { expiration = rrsig->rrsig.expiration * USEC_PER_SEC; inception = rrsig->rrsig.inception * USEC_PER_SEC; + /* Consider inverted validity intervals as expired */ if (inception > expiration) - return -EKEYREJECTED; + return true; /* Permit a certain amount of clock skew of 10% of the valid * time range. This takes inspiration from unbound's @@ -498,6 +545,35 @@ static int algorithm_to_gcrypt_md(uint8_t algorithm) { } } +static void dnssec_fix_rrset_ttl( + DnsResourceRecord *list[], + unsigned n, + DnsResourceRecord *rrsig, + usec_t realtime) { + + unsigned k; + + assert(list); + assert(n > 0); + assert(rrsig); + + for (k = 0; k < n; k++) { + DnsResourceRecord *rr = list[k]; + + /* Pick the TTL as the minimum of the RR's TTL, the + * RR's original TTL according to the RRSIG and the + * RRSIG's own TTL, see RFC 4035, Section 5.3.3 */ + rr->ttl = MIN3(rr->ttl, rrsig->rrsig.original_ttl, rrsig->ttl); + rr->expiry = rrsig->rrsig.expiration * USEC_PER_SEC; + + /* Copy over information about the signer and wildcard source of synthesis */ + rr->n_skip_labels_source = rrsig->n_skip_labels_source; + rr->n_skip_labels_signer = rrsig->n_skip_labels_signer; + } + + rrsig->expiry = rrsig->rrsig.expiration * USEC_PER_SEC; +} + int dnssec_verify_rrset( DnsAnswer *a, const DnsResourceKey *key, @@ -507,13 +583,14 @@ int dnssec_verify_rrset( DnssecResult *result) { uint8_t wire_format_name[DNS_WIRE_FOMAT_HOSTNAME_MAX]; - size_t hash_size; - void *hash; DnsResourceRecord **list, *rr; + const char *source, *name; gcry_md_hd_t md = NULL; int r, md_algorithm; - bool wildcard = false; size_t k, n = 0; + size_t hash_size; + void *hash; + bool wildcard; assert(key); assert(rrsig); @@ -534,6 +611,14 @@ int dnssec_verify_rrset( if (md_algorithm < 0) return md_algorithm; + r = dnssec_rrsig_prepare(rrsig); + if (r == -EINVAL) { + *result = DNSSEC_INVALID; + return r; + } + if (r < 0) + return r; + r = dnssec_rrsig_expired(rrsig, realtime); if (r < 0) return r; @@ -542,6 +627,52 @@ int dnssec_verify_rrset( return 0; } + name = DNS_RESOURCE_KEY_NAME(key); + + /* Some keys may only appear signed in the zone apex, and are invalid anywhere else. (SOA, NS...) */ + if (dns_type_apex_only(rrsig->rrsig.type_covered)) { + r = dns_name_equal(rrsig->rrsig.signer, name); + if (r < 0) + return r; + if (r == 0) { + *result = DNSSEC_INVALID; + return 0; + } + } + + /* OTOH DS RRs may not appear in the zone apex, but are valid everywhere else. */ + if (rrsig->rrsig.type_covered == DNS_TYPE_DS) { + r = dns_name_equal(rrsig->rrsig.signer, name); + if (r < 0) + return r; + if (r > 0) { + *result = DNSSEC_INVALID; + return 0; + } + } + + /* Determine the "Source of Synthesis" and whether this is a wildcard RRSIG */ + r = dns_name_suffix(name, rrsig->rrsig.labels, &source); + if (r < 0) + return r; + if (r > 0 && !dns_type_may_wildcard(rrsig->rrsig.type_covered)) { + /* We refuse to validate NSEC3 or SOA RRs that are synthesized from wildcards */ + *result = DNSSEC_INVALID; + return 0; + } + if (r == 1) { + /* If we stripped a single label, then let's see if that maybe was "*". If so, we are not really + * synthesized from a wildcard, we are the wildcard itself. Treat that like a normal name. */ + r = dns_name_startswith(name, "*"); + if (r < 0) + return r; + if (r > 0) + source = name; + + wildcard = r == 0; + } else + wildcard = r > 0; + /* Collect all relevant RRs in a single array, so that we can look at the RRset */ list = newa(DnsResourceRecord *, dns_answer_size(a)); @@ -592,22 +723,19 @@ int dnssec_verify_rrset( goto finish; gcry_md_write(md, wire_format_name, r); + /* Convert the source of synthesis into wire format */ + r = dns_name_to_wire_format(source, wire_format_name, sizeof(wire_format_name), true); + if (r < 0) + goto finish; + for (k = 0; k < n; k++) { - const char *suffix; size_t l; + rr = list[k]; - r = dns_name_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rrsig->rrsig.labels, &suffix); - if (r < 0) - goto finish; - if (r > 0) /* This is a wildcard! */ { + /* Hash the source of synthesis. If this is a wildcard, then prefix it with the *. label */ + if (wildcard) gcry_md_write(md, (uint8_t[]) { 1, '*'}, 2); - wildcard = true; - } - - r = dns_name_to_wire_format(suffix, wire_format_name, sizeof(wire_format_name), true); - if (r < 0) - goto finish; gcry_md_write(md, wire_format_name, r); md_add_uint16(md, rr->key->type); @@ -654,12 +782,17 @@ int dnssec_verify_rrset( if (r < 0) goto finish; - if (!r) + /* Now, fix the ttl, expiry, and remember the synthesizing source and the signer */ + if (r > 0) + dnssec_fix_rrset_ttl(list, n, rrsig, realtime); + + if (r == 0) *result = DNSSEC_INVALID; else if (wildcard) *result = DNSSEC_VALIDATED_WILDCARD; else *result = DNSSEC_VALIDATED; + r = 0; finish: @@ -698,8 +831,6 @@ int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnske } int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig) { - int r; - assert(key); assert(rrsig); @@ -712,45 +843,9 @@ int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig) if (rrsig->rrsig.type_covered != key->type) return 0; - /* Make sure signer is a parent of the RRset */ - r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(rrsig->key), rrsig->rrsig.signer); - if (r <= 0) - return r; - - /* Make sure the owner name has at least as many labels as the "label" fields indicates. */ - r = dns_name_count_labels(DNS_RESOURCE_KEY_NAME(rrsig->key)); - if (r < 0) - return r; - if (r < rrsig->rrsig.labels) - return 0; - return dns_name_equal(DNS_RESOURCE_KEY_NAME(rrsig->key), DNS_RESOURCE_KEY_NAME(key)); } -static int dnssec_fix_rrset_ttl(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord *rrsig, usec_t realtime) { - DnsResourceRecord *rr; - int r; - - assert(key); - assert(rrsig); - - DNS_ANSWER_FOREACH(rr, a) { - r = dns_resource_key_equal(key, rr->key); - if (r < 0) - return r; - if (r == 0) - continue; - - /* Pick the TTL as the minimum of the RR's TTL, the - * RR's original TTL according to the RRSIG and the - * RRSIG's own TTL, see RFC 4035, Section 5.3.3 */ - rr->ttl = MIN3(rr->ttl, rrsig->rrsig.original_ttl, rrsig->ttl); - rr->expiry = rrsig->rrsig.expiration * USEC_PER_SEC; - } - - return 0; -} - int dnssec_verify_rrset_search( DnsAnswer *a, const DnsResourceKey *key, @@ -820,10 +915,6 @@ int dnssec_verify_rrset_search( case DNSSEC_VALIDATED_WILDCARD: /* Yay, the RR has been validated, * return immediately, but fix up the expiry */ - r = dnssec_fix_rrset_ttl(a, key, rrsig, realtime); - if (r < 0) - return r; - if (ret_rrsig) *ret_rrsig = rrsig; @@ -911,16 +1002,6 @@ int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max) { return r; if (r == 0) break; - if (r > 0) { - int k; - - /* DNSSEC validation is always done on the ASCII version of the label */ - k = dns_label_apply_idna(buffer, r, buffer, buffer_max); - if (k < 0) - return k; - if (k > 0) - r = k; - } if (buffer_max < (size_t) r + 2) return -ENOBUFS; @@ -974,7 +1055,7 @@ static int digest_to_gcrypt_md(uint8_t algorithm) { } } -int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds, bool mask_revoke) { +int dnssec_verify_dnskey_by_ds(DnsResourceRecord *dnskey, DnsResourceRecord *ds, bool mask_revoke) { char owner_name[DNSSEC_CANONICAL_HOSTNAME_MAX]; gcry_md_hd_t md = NULL; size_t hash_size; @@ -1044,7 +1125,7 @@ finish: return r; } -int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ds) { +int dnssec_verify_dnskey_by_ds_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ds) { DnsResourceRecord *ds; DnsAnswerFlags flags; int r; @@ -1061,7 +1142,6 @@ int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ if (ds->key->type != DNS_TYPE_DS) continue; - if (ds->key->class != dnskey->key->class) continue; @@ -1071,9 +1151,9 @@ int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ if (r == 0) continue; - r = dnssec_verify_dnskey(dnskey, ds, false); - if (r == -EKEYREJECTED) - return 0; /* The DNSKEY is revoked or otherwise invalid, we won't bless it */ + r = dnssec_verify_dnskey_by_ds(dnskey, ds, false); + if (IN_SET(r, -EKEYREJECTED, -EOPNOTSUPP)) + return 0; /* The DNSKEY is revoked or otherwise invalid, or we don't support the digest algorithm */ if (r < 0) return r; if (r > 0) @@ -1190,6 +1270,13 @@ static int nsec3_is_good(DnsResourceRecord *rr, DnsResourceRecord *nsec3) { if (rr->nsec3.iterations > NSEC3_ITERATIONS_MAX) return 0; + /* Ignore NSEC3 RRs generated from wildcards */ + if (rr->n_skip_labels_source != 0) + return 0; + /* Ignore NSEC3 RRs that are located anywhere else than one label below the zone */ + if (rr->n_skip_labels_signer != 1) + return 0; + if (!nsec3) return 1; @@ -1223,6 +1310,7 @@ static int nsec3_is_good(DnsResourceRecord *rr, DnsResourceRecord *nsec3) { if (r == 0) return 0; + /* Make sure both have the same parent */ return dns_name_equal(a, b); } @@ -1274,8 +1362,8 @@ static int nsec3_hashed_domain_make(DnsResourceRecord *nsec3, const char *domain * name uses an NSEC3 record with the opt-out bit set. Lastly, if we are given insufficient NSEC3 records * to conclude anything we indicate this by returning NO_RR. */ static int dnssec_test_nsec3(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl) { - _cleanup_free_ char *next_closer_domain = NULL, *wildcard = NULL, *wildcard_domain = NULL; - const char *zone, *p, *pp = NULL; + _cleanup_free_ char *next_closer_domain = NULL, *wildcard_domain = NULL; + const char *zone, *p, *pp = NULL, *wildcard; DnsResourceRecord *rr, *enclosure_rr, *zone_rr, *wildcard_rr = NULL; DnsAnswerFlags flags; int hashed_size, r; @@ -1401,10 +1489,7 @@ found_closest_encloser: /* Prove that there is no next closer and whether or not there is a wildcard domain. */ - wildcard = strappend("*.", p); - if (!wildcard) - return -ENOMEM; - + wildcard = strjoina("*.", p); r = nsec3_hashed_domain_make(enclosure_rr, wildcard, zone, &wildcard_domain); if (r < 0) return r; @@ -1517,10 +1602,158 @@ found_closest_encloser: return 0; } +static int dnssec_nsec_wildcard_equal(DnsResourceRecord *rr, const char *name) { + char label[DNS_LABEL_MAX]; + const char *n; + int r; + + assert(rr); + assert(rr->key->type == DNS_TYPE_NSEC); + + /* Checks whether the specified RR has a name beginning in "*.", and if the rest is a suffix of our name */ + + if (rr->n_skip_labels_source != 1) + return 0; + + n = DNS_RESOURCE_KEY_NAME(rr->key); + r = dns_label_unescape(&n, label, sizeof(label)); + if (r <= 0) + return r; + if (r != 1 || label[0] != '*') + return 0; + + return dns_name_endswith(name, n); +} + +static int dnssec_nsec_in_path(DnsResourceRecord *rr, const char *name) { + const char *nn, *common_suffix; + int r; + + assert(rr); + assert(rr->key->type == DNS_TYPE_NSEC); + + /* Checks whether the specified nsec RR indicates that name is an empty non-terminal (ENT) + * + * A couple of examples: + * + * NSEC bar → waldo.foo.bar: indicates that foo.bar exists and is an ENT + * NSEC waldo.foo.bar → yyy.zzz.xoo.bar: indicates that xoo.bar and zzz.xoo.bar exist and are ENTs + * NSEC yyy.zzz.xoo.bar → bar: indicates pretty much nothing about ENTs + */ + + /* First, determine parent of next domain. */ + nn = rr->nsec.next_domain_name; + r = dns_name_parent(&nn); + if (r <= 0) + return r; + + /* If the name we just determined is not equal or child of the name we are interested in, then we can't say + * anything at all. */ + r = dns_name_endswith(nn, name); + if (r <= 0) + return r; + + /* If the name we we are interested in is not a prefix of the common suffix of the NSEC RR's owner and next domain names, then we can't say anything either. */ + r = dns_name_common_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rr->nsec.next_domain_name, &common_suffix); + if (r < 0) + return r; + + return dns_name_endswith(name, common_suffix); +} + +static int dnssec_nsec_from_parent_zone(DnsResourceRecord *rr, const char *name) { + int r; + + assert(rr); + assert(rr->key->type == DNS_TYPE_NSEC); + + /* Checks whether this NSEC originates to the parent zone or the child zone. */ + + r = dns_name_parent(&name); + if (r <= 0) + return r; + + r = dns_name_equal(name, DNS_RESOURCE_KEY_NAME(rr->key)); + if (r <= 0) + return r; + + /* DNAME, and NS without SOA is an indication for a delegation. */ + if (bitmap_isset(rr->nsec.types, DNS_TYPE_DNAME)) + return 1; + + if (bitmap_isset(rr->nsec.types, DNS_TYPE_NS) && !bitmap_isset(rr->nsec.types, DNS_TYPE_SOA)) + return 1; + + return 0; +} + +static int dnssec_nsec_covers(DnsResourceRecord *rr, const char *name) { + const char *common_suffix, *p; + int r; + + assert(rr); + assert(rr->key->type == DNS_TYPE_NSEC); + + /* Checks whether the "Next Closer" is witin the space covered by the specified RR. */ + + r = dns_name_common_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rr->nsec.next_domain_name, &common_suffix); + if (r < 0) + return r; + + for (;;) { + p = name; + r = dns_name_parent(&name); + if (r < 0) + return r; + if (r == 0) + return 0; + + r = dns_name_equal(name, common_suffix); + if (r < 0) + return r; + if (r > 0) + break; + } + + /* p is now the "Next Closer". */ + + return dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), p, rr->nsec.next_domain_name); +} + +static int dnssec_nsec_covers_wildcard(DnsResourceRecord *rr, const char *name) { + const char *common_suffix, *wc; + int r; + + assert(rr); + assert(rr->key->type == DNS_TYPE_NSEC); + + /* Checks whether the "Wildcard at the Closest Encloser" is within the space covered by the specified + * RR. Specifically, checks whether 'name' has the common suffix of the NSEC RR's owner and next names as + * suffix, and whether the NSEC covers the name generated by that suffix prepended with an asterisk label. + * + * NSEC bar → waldo.foo.bar: indicates that *.bar and *.foo.bar do not exist + * NSEC waldo.foo.bar → yyy.zzz.xoo.bar: indicates that *.xoo.bar and *.zzz.xoo.bar do not exist (and more ...) + * NSEC yyy.zzz.xoo.bar → bar: indicates that a number of wildcards don#t exist either... + */ + + r = dns_name_common_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rr->nsec.next_domain_name, &common_suffix); + if (r < 0) + return r; + + /* If the common suffix is not shared by the name we are interested in, it has nothing to say for us. */ + r = dns_name_endswith(name, common_suffix); + if (r <= 0) + return r; + + wc = strjoina("*.", common_suffix, NULL); + return dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), wc, rr->nsec.next_domain_name); +} + int dnssec_nsec_test(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl) { - DnsResourceRecord *rr; - bool have_nsec3 = false; + bool have_nsec3 = false, covering_rr_authenticated = false, wildcard_rr_authenticated = false; + DnsResourceRecord *rr, *covering_rr = NULL, *wildcard_rr = NULL; DnsAnswerFlags flags; + const char *name; int r; assert(key); @@ -1528,53 +1761,117 @@ int dnssec_nsec_test(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *r /* Look for any NSEC/NSEC3 RRs that say something about the specified key. */ + name = DNS_RESOURCE_KEY_NAME(key); + DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) { if (rr->key->class != key->class) continue; - switch (rr->key->type) { + have_nsec3 = have_nsec3 || (rr->key->type == DNS_TYPE_NSEC3); - case DNS_TYPE_NSEC: + if (rr->key->type != DNS_TYPE_NSEC) + continue; + + /* The following checks only make sense for NSEC RRs that are not expanded from a wildcard */ + r = dns_resource_record_is_synthetic(rr); + if (r < 0) + return r; + if (r > 0) + continue; - r = dns_name_equal(DNS_RESOURCE_KEY_NAME(rr->key), DNS_RESOURCE_KEY_NAME(key)); + /* Check if this is a direct match. If so, we have encountered a NODATA case */ + r = dns_name_equal(DNS_RESOURCE_KEY_NAME(rr->key), name); + if (r < 0) + return r; + if (r == 0) { + /* If it's not a direct match, maybe it's a wild card match? */ + r = dnssec_nsec_wildcard_equal(rr, name); if (r < 0) return r; - if (r > 0) { - if (bitmap_isset(rr->nsec.types, key->type)) - *result = DNSSEC_NSEC_FOUND; - else if (bitmap_isset(rr->nsec.types, DNS_TYPE_CNAME)) - *result = DNSSEC_NSEC_CNAME; - else - *result = DNSSEC_NSEC_NODATA; - - if (authenticated) - *authenticated = flags & DNS_ANSWER_AUTHENTICATED; - if (ttl) - *ttl = rr->ttl; - - return 0; + } + if (r > 0) { + if (key->type == DNS_TYPE_DS) { + /* If we look for a DS RR and the server sent us the NSEC RR of the child zone + * we have a problem. For DS RRs we want the NSEC RR from the parent */ + if (bitmap_isset(rr->nsec.types, DNS_TYPE_SOA)) + continue; + } else { + /* For all RR types, ensure that if NS is set SOA is set too, so that we know + * we got the child's NSEC. */ + if (bitmap_isset(rr->nsec.types, DNS_TYPE_NS) && + !bitmap_isset(rr->nsec.types, DNS_TYPE_SOA)) + continue; } - r = dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), DNS_RESOURCE_KEY_NAME(key), rr->nsec.next_domain_name); - if (r < 0) - return r; - if (r > 0) { - *result = DNSSEC_NSEC_NXDOMAIN; + if (bitmap_isset(rr->nsec.types, key->type)) + *result = DNSSEC_NSEC_FOUND; + else if (bitmap_isset(rr->nsec.types, DNS_TYPE_CNAME)) + *result = DNSSEC_NSEC_CNAME; + else + *result = DNSSEC_NSEC_NODATA; - if (authenticated) - *authenticated = flags & DNS_ANSWER_AUTHENTICATED; - if (ttl) - *ttl = rr->ttl; + if (authenticated) + *authenticated = flags & DNS_ANSWER_AUTHENTICATED; + if (ttl) + *ttl = rr->ttl; - return 0; - } - break; + return 0; + } - case DNS_TYPE_NSEC3: - have_nsec3 = true; - break; + /* Check if the name we are looking for is an empty non-terminal within the owner or next name + * of the NSEC RR. */ + r = dnssec_nsec_in_path(rr, name); + if (r < 0) + return r; + if (r > 0) { + *result = DNSSEC_NSEC_NODATA; + + if (authenticated) + *authenticated = flags & DNS_ANSWER_AUTHENTICATED; + if (ttl) + *ttl = rr->ttl; + + return 0; } + + /* The following two "covering" checks, are not useful if the NSEC is from the parent */ + r = dnssec_nsec_from_parent_zone(rr, name); + if (r < 0) + return r; + if (r > 0) + continue; + + /* Check if this NSEC RR proves the absence of an explicit RR under this name */ + r = dnssec_nsec_covers(rr, name); + if (r < 0) + return r; + if (r > 0 && (!covering_rr || !covering_rr_authenticated)) { + covering_rr = rr; + covering_rr_authenticated = flags & DNS_ANSWER_AUTHENTICATED; + } + + /* Check if this NSEC RR proves the absence of a wildcard RR under this name */ + r = dnssec_nsec_covers_wildcard(rr, name); + if (r < 0) + return r; + if (r > 0 && (!wildcard_rr || !wildcard_rr_authenticated)) { + wildcard_rr = rr; + wildcard_rr_authenticated = flags & DNS_ANSWER_AUTHENTICATED; + } + } + + if (covering_rr && wildcard_rr) { + /* If we could prove that neither the name itself, nor the wildcard at the closest encloser exists, we + * proved the NXDOMAIN case. */ + *result = DNSSEC_NSEC_NXDOMAIN; + + if (authenticated) + *authenticated = covering_rr_authenticated && wildcard_rr_authenticated; + if (ttl) + *ttl = MIN(covering_rr->ttl, wildcard_rr->ttl); + + return 0; } /* OK, this was not sufficient. Let's see if NSEC3 can help. */ @@ -1586,7 +1883,7 @@ int dnssec_nsec_test(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *r return 0; } -int dnssec_nsec_test_between(DnsAnswer *answer, const char *name, const char *zone, bool *authenticated) { +int dnssec_nsec_test_enclosed(DnsAnswer *answer, uint16_t type, const char *name, const char *zone, bool *authenticated) { DnsResourceRecord *rr; DnsAnswerFlags flags; int r; @@ -1600,15 +1897,20 @@ int dnssec_nsec_test_between(DnsAnswer *answer, const char *name, const char *zo DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) { bool found = false; - r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(rr->key), zone); - if (r < 0) - return r; - if (r == 0) + if (rr->key->type != type && type != DNS_TYPE_ANY) continue; switch (rr->key->type) { case DNS_TYPE_NSEC: + + /* We only care for NSEC RRs from the indicated zone */ + r = dns_resource_record_is_signer(rr, zone); + if (r < 0) + return r; + if (r == 0) + continue; + r = dns_name_between(DNS_RESOURCE_KEY_NAME(rr->key), name, rr->nsec.next_domain_name); if (r < 0) return r; @@ -1619,6 +1921,13 @@ int dnssec_nsec_test_between(DnsAnswer *answer, const char *name, const char *zo case DNS_TYPE_NSEC3: { _cleanup_free_ char *hashed_domain = NULL, *next_hashed_domain = NULL; + /* We only care for NSEC3 RRs from the indicated zone */ + r = dns_resource_record_is_signer(rr, zone); + if (r < 0) + return r; + if (r == 0) + continue; + r = nsec3_is_good(rr, NULL); if (r < 0) return r; @@ -1667,6 +1976,145 @@ int dnssec_nsec_test_between(DnsAnswer *answer, const char *name, const char *zo return 0; } +static int dnssec_test_positive_wildcard_nsec3( + DnsAnswer *answer, + const char *name, + const char *source, + const char *zone, + bool *authenticated) { + + const char *next_closer = NULL; + int r; + + /* Run a positive NSEC3 wildcard proof. Specifically: + * + * A proof that the the "next closer" of the generating wildcard does not exist. + * + * Note a key difference between the NSEC3 and NSEC versions of the proof. NSEC RRs don't have to exist for + * empty non-transients. NSEC3 RRs however have to. This means it's sufficient to check if the next closer name + * exists for the NSEC3 RR and we are done. + * + * To prove that a.b.c.d.e.f is rightfully synthesized from a wildcard *.d.e.f all we have to check is that + * c.d.e.f does not exist. */ + + for (;;) { + next_closer = name; + r = dns_name_parent(&name); + if (r < 0) + return r; + if (r == 0) + return 0; + + r = dns_name_equal(name, source); + if (r < 0) + return r; + if (r > 0) + break; + } + + return dnssec_nsec_test_enclosed(answer, DNS_TYPE_NSEC3, next_closer, zone, authenticated); +} + +static int dnssec_test_positive_wildcard_nsec( + DnsAnswer *answer, + const char *name, + const char *source, + const char *zone, + bool *_authenticated) { + + bool authenticated = true; + int r; + + /* Run a positive NSEC wildcard proof. Specifically: + * + * A proof that there's neither a wildcard name nor a non-wildcard name that is a suffix of the name "name" and + * a prefix of the synthesizing source "source" in the zone "zone". + * + * See RFC 5155, Section 8.8 and RFC 4035, Section 5.3.4 + * + * Note that if we want to prove that a.b.c.d.e.f is rightfully synthesized from a wildcard *.d.e.f, then we + * have to prove that none of the following exist: + * + * 1) a.b.c.d.e.f + * 2) *.b.c.d.e.f + * 3) b.c.d.e.f + * 4) *.c.d.e.f + * 5) c.d.e.f + * + */ + + for (;;) { + _cleanup_free_ char *wc = NULL; + bool a = false; + + /* Check if there's an NSEC or NSEC3 RR that proves that the mame we determined is really non-existing, + * i.e between the owner name and the next name of an NSEC RR. */ + r = dnssec_nsec_test_enclosed(answer, DNS_TYPE_NSEC, name, zone, &a); + if (r <= 0) + return r; + + authenticated = authenticated && a; + + /* Strip one label off */ + r = dns_name_parent(&name); + if (r <= 0) + return r; + + /* Did we reach the source of synthesis? */ + r = dns_name_equal(name, source); + if (r < 0) + return r; + if (r > 0) { + /* Successful exit */ + *_authenticated = authenticated; + return 1; + } + + /* Safety check, that the source of synthesis is still our suffix */ + r = dns_name_endswith(name, source); + if (r < 0) + return r; + if (r == 0) + return -EBADMSG; + + /* Replace the label we stripped off with an asterisk */ + wc = strappend("*.", name); + if (!wc) + return -ENOMEM; + + /* And check if the proof holds for the asterisk name, too */ + r = dnssec_nsec_test_enclosed(answer, DNS_TYPE_NSEC, wc, zone, &a); + if (r <= 0) + return r; + + authenticated = authenticated && a; + /* In the next iteration we'll check the non-asterisk-prefixed version */ + } +} + +int dnssec_test_positive_wildcard( + DnsAnswer *answer, + const char *name, + const char *source, + const char *zone, + bool *authenticated) { + + int r; + + assert(name); + assert(source); + assert(zone); + assert(authenticated); + + r = dns_answer_contains_zone_nsec3(answer, zone); + if (r < 0) + return r; + if (r > 0) + return dnssec_test_positive_wildcard_nsec3(answer, name, source, zone, authenticated); + else + return dnssec_test_positive_wildcard_nsec(answer, name, source, zone, authenticated); +} + static const char* const dnssec_result_table[_DNSSEC_RESULT_MAX] = { [DNSSEC_VALIDATED] = "validated", [DNSSEC_VALIDATED_WILDCARD] = "validated-wildcard", |