diff options
| -rw-r--r-- | src/resolve/resolved-dns-answer.c | 27 | ||||
| -rw-r--r-- | src/resolve/resolved-dns-answer.h | 1 | ||||
| -rw-r--r-- | src/resolve/resolved-dns-dnssec.c | 144 | ||||
| -rw-r--r-- | src/resolve/resolved-dns-dnssec.h | 5 | ||||
| -rw-r--r-- | src/resolve/resolved-dns-transaction.c | 26 |
5 files changed, 186 insertions, 17 deletions
diff --git a/src/resolve/resolved-dns-answer.c b/src/resolve/resolved-dns-answer.c index b50558e280..c359432a7a 100644 --- a/src/resolve/resolved-dns-answer.c +++ b/src/resolve/resolved-dns-answer.c @@ -320,6 +320,33 @@ int dns_answer_contains_nsec_or_nsec3(DnsAnswer *a) { return false; } +int dns_answer_contains_zone_nsec3(DnsAnswer *answer, const char *zone) { + DnsResourceRecord *rr; + int r; + + /* Checks whether the specified answer contains at least one NSEC3 RR in the specified zone */ + + DNS_ANSWER_FOREACH(rr, answer) { + const char *p; + + if (rr->key->type != DNS_TYPE_NSEC3) + continue; + + p = DNS_RESOURCE_KEY_NAME(rr->key); + r = dns_name_parent(&p); + if (r < 0) + return r; + if (r == 0) + continue; + + r = dns_name_equal(p, zone); + if (r != 0) + return r; + } + + return false; +} + int dns_answer_find_soa(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord **ret, DnsAnswerFlags *flags) { DnsResourceRecord *rr, *soa = NULL; DnsAnswerFlags rr_flags, soa_flags = 0; diff --git a/src/resolve/resolved-dns-answer.h b/src/resolve/resolved-dns-answer.h index 715e487d94..3eff21f8d0 100644 --- a/src/resolve/resolved-dns-answer.h +++ b/src/resolve/resolved-dns-answer.h @@ -64,6 +64,7 @@ int dns_answer_match_key(DnsAnswer *a, const DnsResourceKey *key, DnsAnswerFlags int dns_answer_contains_rr(DnsAnswer *a, DnsResourceRecord *rr, DnsAnswerFlags *combined_flags); int dns_answer_contains_key(DnsAnswer *a, const DnsResourceKey *key, DnsAnswerFlags *combined_flags); int dns_answer_contains_nsec_or_nsec3(DnsAnswer *a); +int dns_answer_contains_zone_nsec3(DnsAnswer *answer, const char *zone); int dns_answer_find_soa(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord **ret, DnsAnswerFlags *flags); int dns_answer_find_cname_or_dname(DnsAnswer *a, const DnsResourceKey *key, DnsResourceRecord **ret, DnsAnswerFlags *flags); diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c index 6f0f8f837e..afff979b5a 100644 --- a/src/resolve/resolved-dns-dnssec.c +++ b/src/resolve/resolved-dns-dnssec.c @@ -1604,7 +1604,7 @@ 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; @@ -1618,6 +1618,9 @@ int dnssec_nsec_test_between(DnsAnswer *answer, const char *name, const char *zo DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) { bool found = false; + if (rr->key->type != type && type != DNS_TYPE_ANY) + continue; + r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(rr->key), zone); if (r < 0) return r; @@ -1685,6 +1688,145 @@ 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", diff --git a/src/resolve/resolved-dns-dnssec.h b/src/resolve/resolved-dns-dnssec.h index 8a9bcf5b91..b9d32db120 100644 --- a/src/resolve/resolved-dns-dnssec.h +++ b/src/resolve/resolved-dns-dnssec.h @@ -83,7 +83,10 @@ typedef enum DnssecNsecResult { } DnssecNsecResult; int dnssec_nsec_test(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated, uint32_t *ttl); -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); + +int dnssec_test_positive_wildcard(DnsAnswer *a, const char *name, const char *source, const char *zone, bool *authenticated); const char* dnssec_result_to_string(DnssecResult m) _const_; DnssecResult dnssec_result_from_string(const char *s) _pure_; diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c index 9ee10f21c8..c7d2d82ecf 100644 --- a/src/resolve/resolved-dns-transaction.c +++ b/src/resolve/resolved-dns-transaction.c @@ -2531,28 +2531,24 @@ int dns_transaction_validate_dnssec(DnsTransaction *t) { if (result == DNSSEC_VALIDATED_WILDCARD) { bool authenticated = false; - const char *suffix; + const char *source; - /* This RRset validated, but as a wildcard. This means we need to proof via NSEC/NSEC3 - * that no matching non-wildcard RR exists. - * - * See RFC 5155, Section 8.8 and RFC 4035, Section 5.3.4*/ + /* This RRset validated, but as a wildcard. This means we need to prove via NSEC/NSEC3 + * that no matching non-wildcard RR exists.*/ - r = dns_name_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rrsig->rrsig.labels, &suffix); + /* First step, determine the source of synthesis */ + r = dns_name_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rrsig->rrsig.labels, &source); if (r < 0) return r; if (r == 0) return -EBADMSG; - r = dns_name_parent(&suffix); - if (r < 0) - return r; - if (r == 0) - return -EBADMSG; - - r = dnssec_nsec_test_between(validated, DNS_RESOURCE_KEY_NAME(rr->key), suffix, &authenticated); - if (r < 0) - return r; + r = dnssec_test_positive_wildcard( + validated, + DNS_RESOURCE_KEY_NAME(rr->key), + source, + rrsig->rrsig.signer, + &authenticated); /* Unless the NSEC proof showed that the key really doesn't exist something is off. */ if (r == 0) |