diff options
| -rw-r--r-- | src/resolve/resolved-dns-answer.c | 1 | ||||
| -rw-r--r-- | src/resolve/resolved-dns-dnssec.c | 183 | ||||
| -rw-r--r-- | src/resolve/resolved-dns-dnssec.h | 15 | ||||
| -rw-r--r-- | src/resolve/resolved-dns-transaction.c | 53 | ||||
| -rw-r--r-- | src/resolve/test-dnssec.c | 35 |
5 files changed, 285 insertions, 2 deletions
diff --git a/src/resolve/resolved-dns-answer.c b/src/resolve/resolved-dns-answer.c index 6a37345e7e..5355303bd3 100644 --- a/src/resolve/resolved-dns-answer.c +++ b/src/resolve/resolved-dns-answer.c @@ -22,6 +22,7 @@ #include "alloc-util.h" #include "dns-domain.h" #include "resolved-dns-answer.h" +#include "resolved-dns-dnssec.h" #include "string-util.h" DnsAnswer *dns_answer_new(unsigned n) { diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c index 9eb54d44db..d7d50c164c 100644 --- a/src/resolve/resolved-dns-dnssec.c +++ b/src/resolve/resolved-dns-dnssec.c @@ -23,6 +23,7 @@ #include "alloc-util.h" #include "dns-domain.h" +#include "hexdecoct.h" #include "resolved-dns-dnssec.h" #include "resolved-dns-packet.h" #include "string-table.h" @@ -795,6 +796,187 @@ int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ return 0; } +int dnssec_nsec3_hash(DnsResourceRecord *nsec3, const char *name, void *ret) { + uint8_t wire_format[DNS_WIRE_FOMAT_HOSTNAME_MAX]; + gcry_md_hd_t md = NULL; + size_t hash_size; + int algorithm; + void *result; + unsigned k; + int r; + + assert(nsec3); + assert(name); + assert(ret); + + if (nsec3->key->type != DNS_TYPE_NSEC3) + return -EINVAL; + + algorithm = digest_to_gcrypt(nsec3->nsec3.algorithm); + if (algorithm < 0) + return algorithm; + + initialize_libgcrypt(); + + hash_size = gcry_md_get_algo_dlen(algorithm); + assert(hash_size > 0); + + if (nsec3->nsec3.next_hashed_name_size != hash_size) + return -EINVAL; + + r = dns_name_to_wire_format(name, wire_format, sizeof(wire_format), true); + if (r < 0) + return r; + + gcry_md_open(&md, algorithm, 0); + if (!md) + return -EIO; + + gcry_md_write(md, wire_format, r); + gcry_md_write(md, nsec3->nsec3.salt, nsec3->nsec3.salt_size); + + result = gcry_md_read(md, 0); + if (!result) { + r = -EIO; + goto finish; + } + + for (k = 0; k < nsec3->nsec3.iterations; k++) { + uint8_t tmp[hash_size]; + memcpy(tmp, result, hash_size); + + gcry_md_reset(md); + gcry_md_write(md, tmp, hash_size); + gcry_md_write(md, nsec3->nsec3.salt, nsec3->nsec3.salt_size); + + result = gcry_md_read(md, 0); + if (!result) { + r = -EIO; + goto finish; + } + } + + memcpy(ret, result, hash_size); + r = (int) hash_size; + +finish: + gcry_md_close(md); + return r; +} + +int dnssec_test_nsec(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result) { + DnsResourceRecord *rr; + int r; + + assert(key); + assert(result); + + /* Look for any NSEC/NSEC3 RRs that say something about the specified key. */ + + DNS_ANSWER_FOREACH(rr, answer) { + + if (rr->key->class != key->class) + continue; + + switch (rr->key->type) { + + case DNS_TYPE_NSEC: + + r = dns_name_equal(DNS_RESOURCE_KEY_NAME(rr->key), DNS_RESOURCE_KEY_NAME(key)); + if (r < 0) + return r; + if (r > 0) { + *result = bitmap_isset(rr->nsec.types, key->type) ? DNSSEC_NSEC_FOUND : DNSSEC_NSEC_NODATA; + return 0; + } + + 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; + return 0; + } + break; + + case DNS_TYPE_NSEC3: { + _cleanup_free_ void *decoded = NULL; + size_t decoded_size; + char label[DNS_LABEL_MAX]; + uint8_t hashed[DNSSEC_HASH_SIZE_MAX]; + int label_length, c, q; + const char *p; + bool covered; + + /* RFC 5155, Section 8.2 says we MUST ignore NSEC3 RRs with flags != 0 or 1 */ + if (!IN_SET(rr->nsec3.flags, 0, 1)) + continue; + + p = DNS_RESOURCE_KEY_NAME(rr->key); + label_length = dns_label_unescape(&p, label, sizeof(label)); + if (label_length < 0) + return label_length; + if (label_length == 0) + continue; + + r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(key), p); + if (r < 0) + return r; + if (r == 0) + continue; + + r = unbase32hexmem(label, label_length, false, &decoded, &decoded_size); + if (r == -EINVAL) + continue; + if (r < 0) + return r; + + if (decoded_size != rr->nsec3.next_hashed_name_size) + continue; + + c = memcmp(decoded, rr->nsec3.next_hashed_name, decoded_size); + if (c == 0) + continue; + + r = dnssec_nsec3_hash(rr, DNS_RESOURCE_KEY_NAME(key), hashed); + /* RFC 5155, Section 8.1 says we MUST ignore NSEC3 RRs with unknown algorithms */ + if (r == -EOPNOTSUPP) + continue; + if (r < 0) + return r; + if ((size_t) r != decoded_size) + continue; + + r = memcmp(decoded, hashed, decoded_size); + if (r == 0) { + *result = bitmap_isset(rr->nsec3.types, key->type) ? DNSSEC_NSEC_FOUND : DNSSEC_NSEC_NODATA; + return 0; + } + + q = memcmp(hashed, rr->nsec3.next_hashed_name, decoded_size); + + covered = c < 0 ? + r < 0 && q < 0 : + q < 0 || r < 0; + + if (covered) { + *result = DNSSEC_NSEC_NXDOMAIN; + return 0; + } + + break; + } + + default: + break; + } + } + + /* No approproate NSEC RR found, report this. */ + *result = DNSSEC_NSEC_NO_RR; + return 0; +} + static const char* const dnssec_mode_table[_DNSSEC_MODE_MAX] = { [DNSSEC_NO] = "no", [DNSSEC_TRUST] = "trust", @@ -811,5 +993,6 @@ static const char* const dnssec_result_table[_DNSSEC_RESULT_MAX] = { [DNSSEC_MISSING_KEY] = "missing-key", [DNSSEC_UNSIGNED] = "unsigned", [DNSSEC_FAILED_AUXILIARY] = "failed-auxiliary", + [DNSSEC_NSEC_MISMATCH] = "nsec-mismatch", }; DEFINE_STRING_TABLE_LOOKUP(dnssec_result, DnssecResult); diff --git a/src/resolve/resolved-dns-dnssec.h b/src/resolve/resolved-dns-dnssec.h index f33abe3e11..442e301302 100644 --- a/src/resolve/resolved-dns-dnssec.h +++ b/src/resolve/resolved-dns-dnssec.h @@ -56,12 +56,16 @@ enum DnssecResult { /* These two are added by the DnsTransaction logic */ DNSSEC_UNSIGNED, DNSSEC_FAILED_AUXILIARY, + DNSSEC_NSEC_MISMATCH, _DNSSEC_RESULT_MAX, _DNSSEC_RESULT_INVALID = -1 }; #define DNSSEC_CANONICAL_HOSTNAME_MAX (DNS_HOSTNAME_MAX + 2) +/* The longest digest we'll ever generate, of all digest algorithms we support */ +#define DNSSEC_HASH_SIZE_MAX (MAX(20, 32)) + int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey); int dnssec_key_match_rrsig(DnsResourceKey *key, DnsResourceRecord *rrsig); @@ -75,6 +79,17 @@ uint16_t dnssec_keytag(DnsResourceRecord *dnskey); int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max); +int dnssec_nsec3_hash(DnsResourceRecord *nsec3, const char *name, void *ret); + +typedef enum DnssecNsecResult { + DNSSEC_NSEC_NO_RR, /* No suitable NSEC/NSEC3 RR found */ + DNSSEC_NSEC_NXDOMAIN, + DNSSEC_NSEC_NODATA, + DNSSEC_NSEC_FOUND, +} DnssecNsecResult; + +int dnssec_test_nsec(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result); + const char* dnssec_mode_to_string(DnssecMode m) _const_; DnssecMode dnssec_mode_from_string(const char *s) _pure_; diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c index 045627340b..f09788b0c6 100644 --- a/src/resolve/resolved-dns-transaction.c +++ b/src/resolve/resolved-dns-transaction.c @@ -1472,8 +1472,57 @@ int dns_transaction_validate_dnssec(DnsTransaction *t) { /* Everything that's now in t->answer is known to be good, hence cacheable. */ t->n_answer_cacheable = (unsigned) -1; /* everything! */ - t->answer_authenticated = true; - t->dnssec_result = DNSSEC_VALIDATED; + /* At this point the answer only contains validated + * RRsets. Now, let's see if it actually answers the question + * we asked. If so, great! If it doesn't, then see if + * NSEC/NSEC3 can prove this. */ + r = dns_answer_match_key(t->answer, t->key); + if (r < 0) + return r; + if (r > 0) { + /* Yes, it answer the question, everything is authenticated. */ + t->dnssec_result = DNSSEC_VALIDATED; + t->answer_rcode = DNS_RCODE_SUCCESS; + t->answer_authenticated = true; + } else if (r == 0) { + DnssecNsecResult nr; + + /* Bummer! Let's check NSEC/NSEC3 */ + r = dnssec_test_nsec(t->answer, t->key, &nr); + if (r < 0) + return r; + + switch (nr) { + + case DNSSEC_NSEC_NXDOMAIN: + /* NSEC proves the domain doesn't exist. Very good. */ + t->dnssec_result = DNSSEC_VALIDATED; + t->answer_rcode = DNS_RCODE_NXDOMAIN; + t->answer_authenticated = true; + break; + + case DNSSEC_NSEC_NODATA: + /* NSEC proves that there's no data here, very good. */ + t->dnssec_result = DNSSEC_VALIDATED; + t->answer_rcode = DNS_RCODE_SUCCESS; + t->answer_authenticated = true; + break; + + case DNSSEC_NSEC_NO_RR: + /* No NSEC data? Bummer! */ + t->dnssec_result = DNSSEC_UNSIGNED; + break; + + case DNSSEC_NSEC_FOUND: + /* NSEC says it needs to be there, but we couldn't find it? Bummer! */ + t->dnssec_result = DNSSEC_NSEC_MISMATCH; + break; + + default: + assert_not_reached("Unexpected NSEC result."); + } + } + return 1; } diff --git a/src/resolve/test-dnssec.c b/src/resolve/test-dnssec.c index cbcb0fd94f..807eeb3d9a 100644 --- a/src/resolve/test-dnssec.c +++ b/src/resolve/test-dnssec.c @@ -27,6 +27,7 @@ #include "resolved-dns-dnssec.h" #include "resolved-dns-rr.h" #include "string-util.h" +#include "hexdecoct.h" static void test_dnssec_verify_rrset2(void) { @@ -305,12 +306,46 @@ static void test_dnssec_canonicalize(void) { test_dnssec_canonicalize_one("FOO..bar.", NULL, -EINVAL); } +static void test_dnssec_nsec3_hash(void) { + static const uint8_t salt[] = { 0xB0, 0x1D, 0xFA, 0xCE }; + static const uint8_t next_hashed_name[] = { 0x84, 0x10, 0x26, 0x53, 0xc9, 0xfa, 0x4d, 0x85, 0x6c, 0x97, 0x82, 0xe2, 0x8f, 0xdf, 0x2d, 0x5e, 0x87, 0x69, 0xc4, 0x52 }; + _cleanup_(dns_resource_record_unrefp) DnsResourceRecord *rr = NULL; + _cleanup_free_ char *a = NULL, *b = NULL; + uint8_t h[DNSSEC_HASH_SIZE_MAX]; + int k; + + /* The NSEC3 RR for eurid.eu on 2015-12-14. */ + rr = dns_resource_record_new_full(DNS_CLASS_IN, DNS_TYPE_NSEC3, "PJ8S08RR45VIQDAQGE7EN3VHKNROTBMM.eurid.eu."); + assert_se(rr); + + rr->nsec3.algorithm = DNSSEC_DIGEST_SHA1; + rr->nsec3.flags = 1; + rr->nsec3.iterations = 1; + rr->nsec3.salt = memdup(salt, sizeof(salt)); + assert_se(rr->nsec3.salt); + rr->nsec3.salt_size = sizeof(salt); + rr->nsec3.next_hashed_name = memdup(next_hashed_name, sizeof(next_hashed_name)); + assert_se(rr->nsec3.next_hashed_name); + rr->nsec3.next_hashed_name_size = sizeof(next_hashed_name); + + assert_se(dns_resource_record_to_string(rr, &a) >= 0); + log_info("NSEC3: %s", a); + + k = dnssec_nsec3_hash(rr, "eurid.eu", &h); + assert_se(k >= 0); + + b = base32hexmem(h, k, false); + assert_se(b); + assert_se(strcasecmp(b, "PJ8S08RR45VIQDAQGE7EN3VHKNROTBMM") == 0); +} + int main(int argc, char*argv[]) { test_dnssec_canonicalize(); test_dnssec_verify_dns_key(); test_dnssec_verify_rrset(); test_dnssec_verify_rrset2(); + test_dnssec_nsec3_hash(); return 0; } |