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-rw-r--r--lib/dnssec.c479
1 files changed, 479 insertions, 0 deletions
diff --git a/lib/dnssec.c b/lib/dnssec.c
new file mode 100644
index 0000000..7490a67
--- /dev/null
+++ b/lib/dnssec.c
@@ -0,0 +1,479 @@
+/* Copyright (C) 2015-2017 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
+ * SPDX-License-Identifier: GPL-3.0-or-later
+ */
+
+#include <assert.h>
+#include <libdnssec/binary.h>
+#include <libdnssec/crypto.h>
+#include <libdnssec/error.h>
+#include <libdnssec/key.h>
+#include <libdnssec/sign.h>
+#include <libknot/descriptor.h>
+#include <libknot/packet/wire.h>
+#include <libknot/rdataset.h>
+#include <libknot/rrset.h>
+#include <libknot/rrtype/dnskey.h>
+#include <libknot/rrtype/nsec.h>
+#include <libknot/rrtype/rrsig.h>
+
+#include "contrib/cleanup.h"
+#include "contrib/wire.h"
+#include "lib/defines.h"
+#include "lib/dnssec/nsec.h"
+#include "lib/dnssec/nsec3.h"
+#include "lib/dnssec/signature.h"
+#include "lib/dnssec.h"
+#include "lib/resolve.h"
+
+/* forward */
+static int kr_rrset_validate_with_key(kr_rrset_validation_ctx_t *vctx,
+ knot_rrset_t *covered, size_t key_pos, const struct dseckey *key);
+
+void kr_crypto_init(void)
+{
+ dnssec_crypto_init();
+}
+
+void kr_crypto_cleanup(void)
+{
+ dnssec_crypto_cleanup();
+}
+
+void kr_crypto_reinit(void)
+{
+ dnssec_crypto_reinit();
+}
+
+#define FLG_WILDCARD_EXPANSION 0x01 /**< Possibly generated by using wildcard expansion. */
+
+/**
+ * Check the RRSIG RR validity according to RFC4035 5.3.1 .
+ * @param flags The flags are going to be set according to validation result.
+ * @param cov_labels Covered RRSet owner label count.
+ * @param rrsigs rdata containing the signatures.
+ * @param key_owner Associated DNSKEY's owner.
+ * @param key_rdata Associated DNSKEY's rdata.
+ * @param keytag Used key tag.
+ * @param zone_name The name of the zone cut.
+ * @param timestamp Validation time.
+ */
+static int validate_rrsig_rr(int *flags, int cov_labels,
+ const knot_rdata_t *rrsigs,
+ const knot_dname_t *key_owner, const knot_rdata_t *key_rdata,
+ uint16_t keytag,
+ const knot_dname_t *zone_name, uint32_t timestamp,
+ kr_rrset_validation_ctx_t *vctx)
+{
+ if (!flags || !rrsigs || !key_owner || !key_rdata || !zone_name) {
+ return kr_error(EINVAL);
+ }
+ /* bullet 5 */
+ if (knot_rrsig_sig_expiration(rrsigs) < timestamp) {
+ vctx->rrs_counters.expired++;
+ return kr_error(EINVAL);
+ }
+ /* bullet 6 */
+ if (knot_rrsig_sig_inception(rrsigs) > timestamp) {
+ vctx->rrs_counters.notyet++;
+ return kr_error(EINVAL);
+ }
+ /* bullet 2 */
+ const knot_dname_t *signer_name = knot_rrsig_signer_name(rrsigs);
+ if (!signer_name || !knot_dname_is_equal(signer_name, zone_name)) {
+ vctx->rrs_counters.signer_invalid++;
+ return kr_error(EAGAIN);
+ }
+ /* bullet 4 */
+ {
+ int rrsig_labels = knot_rrsig_labels(rrsigs);
+ if (rrsig_labels > cov_labels) {
+ vctx->rrs_counters.labels_invalid++;
+ return kr_error(EINVAL);
+ }
+ if (rrsig_labels < cov_labels) {
+ *flags |= FLG_WILDCARD_EXPANSION;
+ }
+ }
+
+ /* bullet 7 */
+ if ((!knot_dname_is_equal(key_owner, signer_name)) ||
+ (knot_dnskey_alg(key_rdata) != knot_rrsig_alg(rrsigs)) ||
+ (keytag != knot_rrsig_key_tag(rrsigs))) {
+ vctx->rrs_counters.key_invalid++;
+ return kr_error(EINVAL);
+ }
+ /* bullet 8 */
+ /* Checked somewhere else. */
+ /* bullet 9 and 10 */
+ /* One of the requirements should be always fulfilled. */
+
+ return kr_ok();
+}
+
+/**
+ * Returns the number of labels that have been added by wildcard expansion.
+ * @param expanded Expanded wildcard.
+ * @param rrsigs RRSet containing the signatures.
+ * @param sig_pos Specifies the signature within the RRSIG RRSet.
+ * @return Number of added labels, -1 on error.
+ */
+static inline int wildcard_radix_len_diff(const knot_dname_t *expanded,
+ const knot_rdata_t *rrsig)
+{
+ if (!expanded || !rrsig) {
+ return -1;
+ }
+
+ return knot_dname_labels(expanded, NULL) - knot_rrsig_labels(rrsig);
+}
+
+int kr_rrset_validate(kr_rrset_validation_ctx_t *vctx, knot_rrset_t *covered)
+{
+ if (!vctx) {
+ return kr_error(EINVAL);
+ }
+ if (!vctx->pkt || !covered || !vctx->keys || !vctx->zone_name) {
+ return kr_error(EINVAL);
+ }
+
+ memset(&vctx->rrs_counters, 0, sizeof(vctx->rrs_counters));
+ for (unsigned i = 0; i < vctx->keys->rrs.count; ++i) {
+ int ret = kr_rrset_validate_with_key(vctx, covered, i, NULL);
+ if (ret == 0) {
+ return ret;
+ }
+ }
+
+ return kr_error(ENOENT);
+}
+
+/**
+ * Validate RRSet using a specific key.
+ * @param vctx Pointer to validation context.
+ * @param covered RRSet covered by a signature. It must be in canonical format.
+ * TTL may get lowered.
+ * @param key_pos Position of the key to be validated with.
+ * @param key Key to be used to validate.
+ * If NULL, then key from DNSKEY RRSet is used.
+ * @return 0 or error code, same as vctx->result.
+ */
+static int kr_rrset_validate_with_key(kr_rrset_validation_ctx_t *vctx,
+ knot_rrset_t *covered,
+ size_t key_pos, const struct dseckey *key)
+{
+ const knot_pkt_t *pkt = vctx->pkt;
+ const knot_rrset_t *keys = vctx->keys;
+ const knot_dname_t *zone_name = vctx->zone_name;
+ uint32_t timestamp = vctx->timestamp;
+ bool has_nsec3 = vctx->has_nsec3;
+ struct dseckey *created_key = NULL;
+
+ /* It's just caller's approximation that the RR is in that particular zone.
+ * We MUST guard against attempts of zones signing out-of-bailiwick records. */
+ if (knot_dname_in_bailiwick(covered->owner, zone_name) < 0) {
+ vctx->result = kr_error(ENOENT);
+ return vctx->result;
+ }
+
+ const knot_rdata_t *key_rdata = knot_rdataset_at(&keys->rrs, key_pos);
+ if (key == NULL) {
+ int ret = kr_dnssec_key_from_rdata(&created_key, keys->owner,
+ key_rdata->data, key_rdata->len);
+ if (ret != 0) {
+ vctx->result = ret;
+ return vctx->result;
+ }
+ key = created_key;
+ }
+ uint16_t keytag = dnssec_key_get_keytag((dnssec_key_t *)key);
+ int covered_labels = knot_dname_labels(covered->owner, NULL);
+ if (knot_dname_is_wildcard(covered->owner)) {
+ /* The asterisk does not count, RFC4034 3.1.3, paragraph 3. */
+ --covered_labels;
+ }
+
+ for (uint16_t i = 0; i < vctx->rrs->len; ++i) {
+ /* Consider every RRSIG that matches and comes from the same query. */
+ const knot_rrset_t *rrsig = vctx->rrs->at[i]->rr;
+ const bool ok = vctx->rrs->at[i]->qry_uid == vctx->qry_uid
+ && rrsig->type == KNOT_RRTYPE_RRSIG
+ && rrsig->rclass == covered->rclass
+ && knot_dname_is_equal(rrsig->owner, covered->owner);
+ if (!ok)
+ continue;
+
+ knot_rdata_t *rdata_j = rrsig->rrs.rdata;
+ for (uint16_t j = 0; j < rrsig->rrs.count; ++j, rdata_j = knot_rdataset_next(rdata_j)) {
+ int val_flgs = 0;
+ int trim_labels = 0;
+ if (knot_rrsig_type_covered(rdata_j) != covered->type) {
+ continue;
+ }
+ kr_rank_set(&vctx->rrs->at[i]->rank, KR_RANK_BOGUS); /* defensive style */
+ vctx->rrs_counters.matching_name_type++;
+ int retv = validate_rrsig_rr(&val_flgs, covered_labels, rdata_j,
+ keys->owner, key_rdata, keytag,
+ zone_name, timestamp, vctx);
+ if (retv == kr_error(EAGAIN)) {
+ kr_dnssec_key_free(&created_key);
+ vctx->result = retv;
+ return retv;
+ } else if (retv != 0) {
+ continue;
+ }
+ if (val_flgs & FLG_WILDCARD_EXPANSION) {
+ trim_labels = wildcard_radix_len_diff(covered->owner, rdata_j);
+ if (trim_labels < 0) {
+ break;
+ }
+ }
+ if (kr_check_signature(rdata_j, (dnssec_key_t *) key, covered, trim_labels) != 0) {
+ vctx->rrs_counters.crypto_invalid++;
+ continue;
+ }
+ if (val_flgs & FLG_WILDCARD_EXPANSION) {
+ int ret = 0;
+ if (!has_nsec3) {
+ ret = kr_nsec_wildcard_answer_response_check(pkt, KNOT_AUTHORITY, covered->owner);
+ } else {
+ ret = kr_nsec3_wildcard_answer_response_check(pkt, KNOT_AUTHORITY, covered->owner, trim_labels - 1);
+ if (ret == kr_error(KNOT_ERANGE)) {
+ ret = 0;
+ vctx->flags |= KR_DNSSEC_VFLG_OPTOUT;
+ }
+ }
+ if (ret != 0) {
+ vctx->rrs_counters.nsec_invalid++;
+ continue;
+ }
+ vctx->flags |= KR_DNSSEC_VFLG_WEXPAND;
+ }
+ /* Validated with current key, OK;
+ * now just trim TTL in case it's over-extended. */
+ const uint32_t ttl_max = MIN(knot_rrsig_original_ttl(rdata_j),
+ knot_rrsig_sig_expiration(rdata_j) - timestamp);
+ if (unlikely(covered->ttl > ttl_max)) {
+ if (VERBOSE_STATUS) {
+ auto_free char
+ *name_str = kr_dname_text(covered->owner),
+ *type_str = kr_rrtype_text(covered->type);
+ QRVERBOSE(NULL, "vldr",
+ "trimming TTL of %s %s: %d -> %d\n",
+ name_str, type_str,
+ (int)covered->ttl, (int)ttl_max);
+ }
+ covered->ttl = ttl_max;
+ }
+
+ kr_dnssec_key_free(&created_key);
+ vctx->result = kr_ok();
+ kr_rank_set(&vctx->rrs->at[i]->rank, KR_RANK_SECURE); /* upgrade from bogus */
+ return vctx->result;
+ }
+ }
+ /* No applicable key found, cannot be validated. */
+ kr_dnssec_key_free(&created_key);
+ vctx->result = kr_error(ENOENT);
+ return vctx->result;
+}
+
+bool kr_ds_algo_support(const knot_rrset_t *ta)
+{
+ assert(ta && ta->type == KNOT_RRTYPE_DS && ta->rclass == KNOT_CLASS_IN);
+ /* Check if at least one DS has a usable algorithm pair. */
+ knot_rdata_t *rdata_i = ta->rrs.rdata;
+ for (uint16_t i = 0; i < ta->rrs.count;
+ ++i, rdata_i = knot_rdataset_next(rdata_i)) {
+ if (dnssec_algorithm_digest_support(knot_ds_digest_type(rdata_i))
+ && dnssec_algorithm_key_support(knot_ds_alg(rdata_i))) {
+ return true;
+ }
+ }
+ return false;
+}
+
+int kr_dnskeys_trusted(kr_rrset_validation_ctx_t *vctx, const knot_rrset_t *ta)
+{
+ const knot_pkt_t *pkt = vctx->pkt;
+ knot_rrset_t *keys = vctx->keys;
+
+ const bool ok = pkt && keys && ta && ta->rrs.count && ta->rrs.rdata
+ && ta->type == KNOT_RRTYPE_DS;
+ if (!ok) {
+ assert(false);
+ return kr_error(EINVAL);
+ }
+
+ /* RFC4035 5.2, bullet 1
+ * The supplied DS record has been authenticated.
+ * It has been validated or is part of a configured trust anchor.
+ */
+ memset(&vctx->rrs_counters, 0, sizeof(vctx->rrs_counters));
+ for (uint16_t i = 0; i < keys->rrs.count; ++i) {
+ /* RFC4035 5.3.1, bullet 8 */ /* ZSK */
+ /* LATER(optim.): more efficient way to iterate than _at() */
+ knot_rdata_t *krr = knot_rdataset_at(&keys->rrs, i);
+ if (!kr_dnssec_key_zsk(krr->data) || kr_dnssec_key_revoked(krr->data)) {
+ continue;
+ }
+
+ struct dseckey *key = NULL;
+ if (kr_dnssec_key_from_rdata(&key, keys->owner, krr->data, krr->len) != 0) {
+ continue;
+ }
+ if (kr_authenticate_referral(ta, (dnssec_key_t *) key) != 0) {
+ kr_dnssec_key_free(&key);
+ continue;
+ }
+ if (kr_rrset_validate_with_key(vctx, keys, i, key) != 0) {
+ kr_dnssec_key_free(&key);
+ continue;
+ }
+ kr_dnssec_key_free(&key);
+ assert (vctx->result == 0);
+ return vctx->result;
+ }
+
+ /* No useable key found */
+ vctx->result = kr_error(ENOENT);
+ return vctx->result;
+}
+
+bool kr_dnssec_key_zsk(const uint8_t *dnskey_rdata)
+{
+ return wire_read_u16(dnskey_rdata) & 0x0100;
+}
+
+bool kr_dnssec_key_ksk(const uint8_t *dnskey_rdata)
+{
+ return wire_read_u16(dnskey_rdata) & 0x0001;
+}
+
+/** Return true if the DNSKEY is revoked. */
+bool kr_dnssec_key_revoked(const uint8_t *dnskey_rdata)
+{
+ return wire_read_u16(dnskey_rdata) & 0x0080;
+}
+
+int kr_dnssec_key_tag(uint16_t rrtype, const uint8_t *rdata, size_t rdlen)
+{
+ if (!rdata || rdlen == 0 || (rrtype != KNOT_RRTYPE_DS && rrtype != KNOT_RRTYPE_DNSKEY)) {
+ return kr_error(EINVAL);
+ }
+ if (rrtype == KNOT_RRTYPE_DS) {
+ return wire_read_u16(rdata);
+ } else if (rrtype == KNOT_RRTYPE_DNSKEY) {
+ struct dseckey *key = NULL;
+ int ret = kr_dnssec_key_from_rdata(&key, NULL, rdata, rdlen);
+ if (ret != 0) {
+ return ret;
+ }
+ uint16_t keytag = dnssec_key_get_keytag((dnssec_key_t *)key);
+ kr_dnssec_key_free(&key);
+ return keytag;
+ } else {
+ return kr_error(EINVAL);
+ }
+}
+
+int kr_dnssec_key_match(const uint8_t *key_a_rdata, size_t key_a_rdlen,
+ const uint8_t *key_b_rdata, size_t key_b_rdlen)
+{
+ dnssec_key_t *key_a = NULL, *key_b = NULL;
+ int ret = kr_dnssec_key_from_rdata((struct dseckey **)&key_a, NULL, key_a_rdata, key_a_rdlen);
+ if (ret != 0) {
+ return ret;
+ }
+ ret = kr_dnssec_key_from_rdata((struct dseckey **)&key_b, NULL, key_b_rdata, key_b_rdlen);
+ if (ret != 0) {
+ dnssec_key_free(key_a);
+ return ret;
+ }
+ /* If the algorithm and the public key match, we can be sure
+ * that they are the same key. */
+ ret = kr_error(ENOENT);
+ dnssec_binary_t pk_a, pk_b;
+ if (dnssec_key_get_algorithm(key_a) == dnssec_key_get_algorithm(key_b) &&
+ dnssec_key_get_pubkey(key_a, &pk_a) == DNSSEC_EOK &&
+ dnssec_key_get_pubkey(key_b, &pk_b) == DNSSEC_EOK) {
+ if (pk_a.size == pk_b.size && memcmp(pk_a.data, pk_b.data, pk_a.size) == 0) {
+ ret = 0;
+ }
+ }
+ dnssec_key_free(key_a);
+ dnssec_key_free(key_b);
+ return ret;
+}
+
+int kr_dnssec_key_from_rdata(struct dseckey **key, const knot_dname_t *kown, const uint8_t *rdata, size_t rdlen)
+{
+ if (!key || !rdata || rdlen == 0) {
+ return kr_error(EINVAL);
+ }
+
+ dnssec_key_t *new_key = NULL;
+ const dnssec_binary_t binary_key = {
+ .size = rdlen,
+ .data = (uint8_t *)rdata
+ };
+
+ int ret = dnssec_key_new(&new_key);
+ if (ret != DNSSEC_EOK) {
+ return kr_error(ENOMEM);
+ }
+ ret = dnssec_key_set_rdata(new_key, &binary_key);
+ if (ret != DNSSEC_EOK) {
+ dnssec_key_free(new_key);
+ return kr_error(ret);
+ }
+ if (kown) {
+ ret = dnssec_key_set_dname(new_key, kown);
+ if (ret != DNSSEC_EOK) {
+ dnssec_key_free(new_key);
+ return kr_error(ENOMEM);
+ }
+ }
+
+ *key = (struct dseckey *) new_key;
+ return kr_ok();
+}
+
+void kr_dnssec_key_free(struct dseckey **key)
+{
+ assert(key);
+
+ dnssec_key_free((dnssec_key_t *) *key);
+ *key = NULL;
+}
+
+int kr_dnssec_matches_name_and_type(const ranked_rr_array_t *rrs, uint32_t qry_uid,
+ const knot_dname_t *name, uint16_t type)
+{
+ int ret = kr_error(ENOENT);
+ for (size_t i = 0; i < rrs->len; ++i) {
+ const ranked_rr_array_entry_t *entry = rrs->at[i];
+ assert(!entry->in_progress);
+ const knot_rrset_t *nsec = entry->rr;
+ if (entry->qry_uid != qry_uid || entry->yielded) {
+ continue;
+ }
+ if (nsec->type != KNOT_RRTYPE_NSEC &&
+ nsec->type != KNOT_RRTYPE_NSEC3) {
+ continue;
+ }
+ if (!kr_rank_test(entry->rank, KR_RANK_SECURE)) {
+ continue;
+ }
+ if (nsec->type == KNOT_RRTYPE_NSEC) {
+ ret = kr_nsec_matches_name_and_type(nsec, name, type);
+ } else {
+ ret = kr_nsec3_matches_name_and_type(nsec, name, type);
+ }
+ if (ret == kr_ok()) {
+ return kr_ok();
+ } else if (ret != kr_error(ENOENT)) {
+ return ret;
+ }
+ }
+ return ret;
+}
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