diff options
Diffstat (limited to '')
| -rw-r--r-- | lib/dnssec.c | 601 | ||||
| -rw-r--r-- | lib/dnssec.h | 191 | ||||
| -rw-r--r-- | lib/dnssec/nsec.c | 315 | ||||
| -rw-r--r-- | lib/dnssec/nsec.h | 69 | ||||
| -rw-r--r-- | lib/dnssec/nsec3.c | 722 | ||||
| -rw-r--r-- | lib/dnssec/nsec3.h | 83 | ||||
| -rw-r--r-- | lib/dnssec/signature.c | 304 | ||||
| -rw-r--r-- | lib/dnssec/signature.h | 29 | ||||
| -rw-r--r-- | lib/dnssec/ta.c | 154 | ||||
| -rw-r--r-- | lib/dnssec/ta.h | 61 |
10 files changed, 2529 insertions, 0 deletions
diff --git a/lib/dnssec.c b/lib/dnssec.c new file mode 100644 index 0000000..d6ae3cc --- /dev/null +++ b/lib/dnssec.c @@ -0,0 +1,601 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#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 "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 dnssec_key *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_alg DNSKEY's algorithm. + * @param keytag Used key tag. + * @param vctx->zone_name The name of the zone cut (and the DNSKEY). + * @param vctx->timestamp Validation time. + */ +static int validate_rrsig_rr(int *flags, int cov_labels, + const knot_rdata_t *rrsigs, + uint8_t key_alg, + uint16_t keytag, + kr_rrset_validation_ctx_t *vctx) +{ + if (kr_fails_assert(flags && rrsigs && vctx && vctx->zone_name)) { + return kr_error(EINVAL); + } + /* bullet 5 */ + if (knot_rrsig_sig_expiration(rrsigs) < vctx->timestamp) { + vctx->rrs_counters.expired++; + return kr_error(EINVAL); + } + /* bullet 6 */ + if (knot_rrsig_sig_inception(rrsigs) > vctx->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, vctx->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 + * Part checked elsewhere: key owner matching the zone_name. */ + if (key_alg != 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); +} + +/** Assuming `rrs` was validated with `sig`, trim its TTL in case it's over-extended. */ +static bool trim_ttl(knot_rrset_t *rrs, const knot_rdata_t *sig, + const kr_rrset_validation_ctx_t *vctx) +{ + /* The trimming logic is a bit complicated. + * + * We respect configured ttl_min over the (signed) original TTL, + * but we very much want to avoid TTLs over signature expiration, + * as that could cause serious issues with downstream validators. + */ + const uint32_t ttl_max = MIN( + MAX(knot_rrsig_original_ttl(sig), vctx->ttl_min), + knot_rrsig_sig_expiration(sig) - vctx->timestamp + ); + if (likely(rrs->ttl <= ttl_max)) + return false; + if (kr_log_is_debug_qry(VALIDATOR, vctx->log_qry)) { + auto_free char *name_str = kr_dname_text(rrs->owner), + *type_str = kr_rrtype_text(rrs->type); + kr_log_q(vctx->log_qry, VALIDATOR, "trimming TTL of %s %s: %d -> %d\n", + name_str, type_str, (int)rrs->ttl, (int)ttl_max); + } + rrs->ttl = ttl_max; + return true; +} + + +typedef struct { + struct dnssec_key *key; + uint8_t alg; + uint16_t tag; +} kr_svldr_key_t; + +struct kr_svldr_ctx { + kr_rrset_validation_ctx_t vctx; + array_t(kr_svldr_key_t) keys; // owned(malloc), also insides via svldr_key_* +}; + +static int svldr_key_new(const knot_rdata_t *rdata, const knot_dname_t *owner, + kr_svldr_key_t *result) +{ + result->alg = knot_dnskey_alg(rdata); + result->key = NULL; // just silence analyzers + int ret = kr_dnssec_key_from_rdata(&result->key, owner, rdata->data, rdata->len); + if (likely(ret == 0)) + result->tag = dnssec_key_get_keytag(result->key); + return ret; +} +static inline void svldr_key_del(kr_svldr_key_t *skey) +{ + kr_dnssec_key_free(&skey->key); +} + +void kr_svldr_free_ctx(struct kr_svldr_ctx *ctx) +{ + if (!ctx) return; + for (ssize_t i = 0; i < ctx->keys.len; ++i) + svldr_key_del(&ctx->keys.at[i]); + array_clear(ctx->keys); + free_const(ctx->vctx.zone_name); + free(ctx); +} +struct kr_svldr_ctx * kr_svldr_new_ctx(const knot_rrset_t *ds, knot_rrset_t *dnskey, + const knot_rdataset_t *dnskey_sigs, uint32_t timestamp, + kr_rrset_validation_ctx_t *err_ctx) +{ + // Basic init. + struct kr_svldr_ctx *ctx = calloc(1, sizeof(*ctx)); + if (unlikely(!ctx)) + return NULL; + ctx->vctx.timestamp = timestamp; // .ttl_min is implicitly zero + ctx->vctx.zone_name = knot_dname_copy(ds->owner, NULL); + if (unlikely(!ctx->vctx.zone_name)) + goto fail; + // Validate the DNSKEY set. + ctx->vctx.keys = dnskey; + if (kr_dnskeys_trusted(&ctx->vctx, dnskey_sigs, ds) != 0) + goto fail; + // Put usable DNSKEYs into ctx->keys. (Some duplication of work happens, but OK.) + array_init(ctx->keys); + array_reserve(ctx->keys, dnskey->rrs.count); + knot_rdata_t *krr = dnskey->rrs.rdata; + for (int i = 0; i < dnskey->rrs.count; ++i, krr = knot_rdataset_next(krr)) { + if (!kr_dnssec_key_zsk(krr->data) || kr_dnssec_key_revoked(krr->data)) + continue; // key not usable for this + kr_svldr_key_t key; + if (unlikely(svldr_key_new(krr, NULL/*seems OK here*/, &key) != 0)) + goto fail; + array_push(ctx->keys, key); + } + return ctx; +fail: + if (err_ctx) + memcpy(err_ctx, &ctx->vctx, sizeof(*err_ctx)); + kr_svldr_free_ctx(ctx); + return NULL; +} + +static int kr_svldr_rrset_with_key(knot_rrset_t *rrs, const knot_rdataset_t *rrsigs, + kr_rrset_validation_ctx_t *vctx, const kr_svldr_key_t *key) +{ + const int covered_labels = knot_dname_labels(rrs->owner, NULL) + - knot_dname_is_wildcard(rrs->owner); + knot_rdata_t *rdata_j = rrsigs->rdata; + for (uint16_t j = 0; j < rrsigs->count; ++j, rdata_j = knot_rdataset_next(rdata_j)) { + if (kr_fails_assert(knot_rrsig_type_covered(rdata_j) == rrs->type)) + continue; //^^ not a problem but no reason to allow them in the API + int val_flgs = 0; + int retv = validate_rrsig_rr(&val_flgs, covered_labels, rdata_j, + key->alg, key->tag, vctx); + if (retv == kr_error(EAGAIN)) { + vctx->result = retv; + return vctx->result; + } else if (retv != 0) { + continue; + } + // We only expect non-expanded wildcard records in input; + // that also means we don't need to perform non-existence proofs. + const int trim_labels = (val_flgs & FLG_WILDCARD_EXPANSION) ? 1 : 0; + if (kr_check_signature(rdata_j, key->key, rrs, trim_labels) == 0) { + trim_ttl(rrs, rdata_j, vctx); + vctx->result = kr_ok(); + return vctx->result; + } else { + vctx->rrs_counters.crypto_invalid++; + } + } + vctx->result = kr_error(ENOENT); + return vctx->result; +} +/* The implementation basically performs "parts of" kr_rrset_validate(). */ +int kr_svldr_rrset(knot_rrset_t *rrs, const knot_rdataset_t *rrsigs, + struct kr_svldr_ctx *ctx) +{ + if (knot_dname_in_bailiwick(rrs->owner, ctx->vctx.zone_name) < 0) { + ctx->vctx.result = kr_error(EAGAIN); + return ctx->vctx.result; + } + for (ssize_t i = 0; i < ctx->keys.len; ++i) { + kr_svldr_rrset_with_key(rrs, rrsigs, &ctx->vctx, &ctx->keys.at[i]); + if (ctx->vctx.result == 0) + break; + } + return ctx->vctx.result; +} + + +/** + * 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 dnssec_key *key) +{ + const knot_pkt_t *pkt = vctx->pkt; + const knot_rrset_t *keys = vctx->keys; + const knot_dname_t *zone_name = vctx->zone_name; + bool has_nsec3 = vctx->has_nsec3; + struct dnssec_key *created_key = NULL; + + if (!knot_dname_is_equal(keys->owner, zone_name) + /* It's just caller's approximation that the RR is in that particular zone, + * so we verify that in the following condition. + * We MUST guard against attempts of zones signing out-of-bailiwick records. */ + || 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(key); + const uint8_t key_alg = knot_dnskey_alg(key_rdata); + /* The asterisk does not count, RFC4034 3.1.3, paragraph 3. */ + const int covered_labels = knot_dname_labels(covered->owner, NULL) + - knot_dname_is_wildcard(covered->owner); + + 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, + key_alg, keytag, 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, 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; + } + + trim_ttl(covered, rdata_j, vctx); + + 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) +{ + if (kr_fails_assert(ta && ta->type == KNOT_RRTYPE_DS && ta->rclass == KNOT_CLASS_IN)) + return false; + /* 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_rdataset_t *sigs, + const knot_rrset_t *ta) +{ + knot_rrset_t *keys = vctx->keys; + const bool ok = keys && ta && ta->rrs.count && ta->rrs.rdata + && ta->type == KNOT_RRTYPE_DS + && knot_dname_is_equal(ta->owner, keys->owner); + if (kr_fails_assert(ok)) + 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. + */ + knot_rdata_t *krr = keys->rrs.rdata; + for (int i = 0; i < keys->rrs.count; ++i, krr = knot_rdataset_next(krr)) { + /* RFC4035 5.3.1, bullet 8 */ /* ZSK */ + if (!kr_dnssec_key_zsk(krr->data) || kr_dnssec_key_revoked(krr->data)) + continue; + + kr_svldr_key_t key; + if (svldr_key_new(krr, keys->owner, &key) != 0) + continue; // it might e.g. be malformed + + int ret = kr_authenticate_referral(ta, key.key); + if (ret == 0) + ret = kr_svldr_rrset_with_key(keys, sigs, vctx, &key); + svldr_key_del(&key); + if (ret == 0) { + kr_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 knot_wire_read_u16(dnskey_rdata) & 0x0100; +} + +bool kr_dnssec_key_ksk(const uint8_t *dnskey_rdata) +{ + return knot_wire_read_u16(dnskey_rdata) & 0x0001; +} + +/** Return true if the DNSKEY is revoked. */ +bool kr_dnssec_key_revoked(const uint8_t *dnskey_rdata) +{ + return knot_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 knot_wire_read_u16(rdata); + } else if (rrtype == KNOT_RRTYPE_DNSKEY) { + struct dnssec_key *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(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(&key_a, NULL, key_a_rdata, key_a_rdlen); + if (ret != 0) { + return ret; + } + ret = kr_dnssec_key_from_rdata(&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 dnssec_key **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 = new_key; + return kr_ok(); +} + +void kr_dnssec_key_free(struct dnssec_key **key) +{ + if (kr_fails_assert(key)) + return; + + dnssec_key_free(*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]; + if (kr_fails_assert(!entry->in_progress)) + return kr_error(EINVAL); + 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; +} diff --git a/lib/dnssec.h b/lib/dnssec.h new file mode 100644 index 0000000..0fbd47c --- /dev/null +++ b/lib/dnssec.h @@ -0,0 +1,191 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#pragma once + +#include "lib/defines.h" +#include "lib/utils.h" +#include <libknot/packet/pkt.h> + +/** + * Initialise cryptographic back-end. + */ +KR_EXPORT +void kr_crypto_init(void); + +/** + * De-initialise cryptographic back-end. + */ +KR_EXPORT +void kr_crypto_cleanup(void); + +/** + * Re-initialise cryptographic back-end. + * @note Must be called after fork() in the child. + */ +KR_EXPORT +void kr_crypto_reinit(void); + +#define KR_DNSSEC_VFLG_WEXPAND 0x01 +#define KR_DNSSEC_VFLG_OPTOUT 0x02 + +/** DNSSEC validation context. */ +struct kr_rrset_validation_ctx { + const knot_pkt_t *pkt; /*!< Packet to be validated. */ + ranked_rr_array_t *rrs; /*!< List of preselected RRs to be validated. */ + knot_section_t section_id; /*!< Section to work with. */ + knot_rrset_t *keys; /*!< DNSKEY RRSet; TTLs may get lowered when validating this set. */ + const knot_dname_t *zone_name; /*!< Name of the zone containing the RRSIG RRSet. */ + uint32_t timestamp; /*!< Validation time. */ + uint32_t ttl_min; /*!< See trim_ttl() for details. */ + bool has_nsec3; /*!< Whether to use NSEC3 validation. */ + uint32_t qry_uid; /*!< Current query uid. */ + uint32_t flags; /*!< Output - Flags. */ + uint32_t err_cnt; /*!< Output - Number of validation failures. */ + uint32_t cname_norrsig_cnt; /*!< Output - Number of CNAMEs missing RRSIGs. */ + + /** Validation result: kr_error() code. + * + * ENOENT: the usual, no suitable signature found + * EAGAIN: encountered a different signer name + * +others + */ + int result; + const struct kr_query *log_qry; /*!< The query; just for logging purposes. */ + struct { + unsigned int matching_name_type; /*!< Name + type matches */ + unsigned int expired; + unsigned int notyet; + unsigned int signer_invalid; /*!< Signer is not zone apex */ + unsigned int labels_invalid; /*!< Number of labels in RRSIG */ + unsigned int key_invalid; /*!< Algorithm/keytag/key owner */ + unsigned int crypto_invalid; + unsigned int nsec_invalid; + } rrs_counters; /*!< Error counters for single RRset validation. */ +}; + +typedef struct kr_rrset_validation_ctx kr_rrset_validation_ctx_t; + +/** + * Validate RRSet. + * @param vctx Pointer to validation context. + * @param covered RRSet covered by a signature. It must be in canonical format. + * Its TTL may get lowered. + * @return 0 or kr_error() code, same as vctx->result (see its docs). + */ +int kr_rrset_validate(kr_rrset_validation_ctx_t *vctx, knot_rrset_t *covered); + +/** + * Return true iff the RRset contains at least one usable DS. See RFC6840 5.2. + */ +KR_EXPORT KR_PURE +bool kr_ds_algo_support(const knot_rrset_t *ta); + +/** + * Check whether the DNSKEY rrset matches the supplied trust anchor RRSet. + * + * @param vctx Pointer to validation context. Note that TTL of vctx->keys may get lowered. + * @param sigs RRSIGs for this DNSKEY set + * @param ta Trusted DS RRSet against which to validate the DNSKEY RRSet. + * @return 0 or error code, same as vctx->result. + */ +int kr_dnskeys_trusted(kr_rrset_validation_ctx_t *vctx, const knot_rdataset_t *sigs, + const knot_rrset_t *ta); + +/** Return true if the DNSKEY can be used as a ZSK. */ +KR_EXPORT KR_PURE +bool kr_dnssec_key_zsk(const uint8_t *dnskey_rdata); + +/** Return true if the DNSKEY indicates being KSK (=> has SEP). */ +KR_EXPORT KR_PURE +bool kr_dnssec_key_ksk(const uint8_t *dnskey_rdata); + +/** Return true if the DNSKEY is revoked. */ +KR_EXPORT KR_PURE +bool kr_dnssec_key_revoked(const uint8_t *dnskey_rdata); + +/** Return DNSKEY tag. + * @param rrtype RR type (either DS or DNSKEY are supported) + * @param rdata Key/digest RDATA. + * @param rdlen RDATA length. + * @return Key tag (positive number), or an error code + */ +KR_EXPORT KR_PURE +int kr_dnssec_key_tag(uint16_t rrtype, const uint8_t *rdata, size_t rdlen); + +/** Return 0 if the two keys are identical. + * @note This compares RDATA only, algorithm and public key must match. + * @param key_a_rdata First key RDATA + * @param key_a_rdlen First key RDATA length + * @param key_b_rdata Second key RDATA + * @param key_b_rdlen Second key RDATA length + * @return 0 if they match or an error code + */ +KR_EXPORT KR_PURE +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); + +/* Opaque DNSSEC key struct; forward declaration from libdnssec. */ +struct dnssec_key; + +/** + * Construct a DNSSEC key. + * @param key Pointer to be set to newly created DNSSEC key. + * @param kown DNSKEY owner name. + * @param rdata DNSKEY RDATA + * @param rdlen DNSKEY RDATA length + * @return 0 or error code; in particular: DNSSEC_INVALID_KEY_ALGORITHM + */ +int kr_dnssec_key_from_rdata(struct dnssec_key **key, const knot_dname_t *kown, const uint8_t *rdata, size_t rdlen); + +/** + * Frees the DNSSEC key. + * @param key Pointer to freed key. + */ +void kr_dnssec_key_free(struct dnssec_key **key); + +/** + * Checks whether NSEC/NSEC3 RR selected by iterator matches the supplied name and type. + * @param rrs Records selected by iterator. + * @param qry_uid Query unique identifier where NSEC/NSEC3 belongs to. + * @param name Name to be checked. + * @param type Type to be checked. + * @return 0 or error code. + */ +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); + + +/* Simple validator API. Main use case: prefill module, i.e. RRs from a zone file. */ + +/** Opaque context for simple validator. */ +struct kr_svldr_ctx; +/** + * Create new context for validating within a given zone. + * + * - `ds` is assumed to be trusted, and it's used to validate `dnskey+dnskey_sigs`. + * - The TTL of `dnskey` may get trimmed. + * - The insides are placed on malloc heap (use _free_ctx). + * - `err_ctx` is optional, for use when error happens (but avoid the inside pointers) + */ +KR_EXPORT +struct kr_svldr_ctx * kr_svldr_new_ctx(const knot_rrset_t *ds, knot_rrset_t *dnskey, + const knot_rdataset_t *dnskey_sigs, uint32_t timestamp, + kr_rrset_validation_ctx_t *err_ctx); +/** Free the context. Passing NULL is OK. */ +KR_EXPORT +void kr_svldr_free_ctx(struct kr_svldr_ctx *ctx); +/** + * Validate an RRset with the associated signatures; assume no wildcard expansions. + * + * - It's caller's responsibility that rrsigs have matching owner, class and type. + * - The TTL of `rrs` may get trimmed. + * - If it's a wildcard other than in its simple `*.` form, it may fail to validate. + * - More generally, non-existence proofs are not supported. + * @return 0 or kr_error() code, same as kr_rrset_validation_ctx::result (see its docs). + */ +KR_EXPORT +int kr_svldr_rrset(knot_rrset_t *rrs, const knot_rdataset_t *rrsigs, + struct kr_svldr_ctx *ctx); + diff --git a/lib/dnssec/nsec.c b/lib/dnssec/nsec.c new file mode 100644 index 0000000..8b17247 --- /dev/null +++ b/lib/dnssec/nsec.c @@ -0,0 +1,315 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#include <stdlib.h> + +#include <libknot/descriptor.h> +#include <libknot/dname.h> +#include <libknot/packet/wire.h> +#include <libknot/rrset.h> +#include <libknot/rrtype/nsec.h> +#include <libknot/rrtype/rrsig.h> +#include <libdnssec/error.h> +#include <libdnssec/nsec.h> + +#include "lib/defines.h" +#include "lib/dnssec/nsec.h" +#include "lib/utils.h" +#include "resolve.h" + +int kr_nsec_children_in_zone_check(const uint8_t *bm, uint16_t bm_size) +{ + if (kr_fails_assert(bm)) + return kr_error(EINVAL); + const bool parent_side = + dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_DNAME) + || (dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_NS) + && !dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_SOA) + ); + return parent_side ? abs(ENOENT) : kr_ok(); + /* LATER: after refactoring, probably also check if signer name equals owner, + * but even without that it's not possible to attack *correctly* signed zones. + */ +} + +/* This block of functions implements a "safe" version of knot_dname_cmp(), + * until that one handles in-label zero bytes correctly. */ +static int lf_cmp(const uint8_t *lf1, const uint8_t *lf2) +{ + /* Compare common part. */ + uint8_t common = lf1[0]; + if (common > lf2[0]) { + common = lf2[0]; + } + int ret = memcmp(lf1 + 1, lf2 + 1, common); + if (ret != 0) { + return ret; + } + + /* If they match, compare lengths. */ + if (lf1[0] < lf2[0]) { + return -1; + } else if (lf1[0] > lf2[0]) { + return 1; + } else { + return 0; + } +} +static void dname_reverse(const knot_dname_t *src, size_t src_len, knot_dname_t *dst) +{ + knot_dname_t *idx = dst + src_len - 1; + kr_require(src[src_len - 1] == '\0'); + *idx = '\0'; + + while (*src) { + uint16_t len = *src + 1; + idx -= len; + memcpy(idx, src, len); + src += len; + } + kr_require(idx == dst); +} +static int dname_cmp(const knot_dname_t *d1, const knot_dname_t *d2) +{ + size_t d1_len = knot_dname_size(d1); + size_t d2_len = knot_dname_size(d2); + + knot_dname_t d1_rev_arr[d1_len], d2_rev_arr[d2_len]; + const knot_dname_t *d1_rev = d1_rev_arr, *d2_rev = d2_rev_arr; + + dname_reverse(d1, d1_len, d1_rev_arr); + dname_reverse(d2, d2_len, d2_rev_arr); + + int res = 0; + while (res == 0 && d1_rev != NULL) { + res = lf_cmp(d1_rev, d2_rev); + d1_rev = knot_wire_next_label(d1_rev, NULL); + d2_rev = knot_wire_next_label(d2_rev, NULL); + } + + kr_require(res != 0 || d2_rev == NULL); + return res; +} + + +/** + * Check whether this nsec proves that there is no closer match for sname. + * + * @param nsec NSEC RRSet. + * @param sname Searched name. + * @return 0 if proves, >0 if not (abs(ENOENT) or abs(EEXIST)), or error code (<0). + */ +static int nsec_covers(const knot_rrset_t *nsec, const knot_dname_t *sname) +{ + if (kr_fails_assert(nsec && sname)) + return kr_error(EINVAL); + const int cmp = dname_cmp(sname, nsec->owner); + if (cmp < 0) return abs(ENOENT); /* 'sname' before 'owner', so can't be covered */ + if (cmp == 0) return abs(EEXIST); /* matched, not covered */ + + /* We have to lower-case 'next' with libknot >= 2.7; see also RFC 6840 5.1. */ + knot_dname_t next[KNOT_DNAME_MAXLEN]; + int ret = knot_dname_to_wire(next, knot_nsec_next(nsec->rrs.rdata), sizeof(next)); + if (kr_fails_assert(ret >= 0)) + return kr_error(ret); + knot_dname_to_lower(next); + + /* If NSEC 'owner' >= 'next', it means that there is nothing after 'owner' */ + const bool is_last_nsec = dname_cmp(nsec->owner, next) >= 0; + const bool in_range = is_last_nsec || dname_cmp(sname, next) < 0; + if (!in_range) + return abs(ENOENT); + /* Before returning kr_ok(), we have to check a special case: + * sname might be under delegation from owner and thus + * not in the zone of this NSEC at all. + */ + if (knot_dname_in_bailiwick(sname, nsec->owner) <= 0) + return kr_ok(); + const uint8_t *bm = knot_nsec_bitmap(nsec->rrs.rdata); + uint16_t bm_size = knot_nsec_bitmap_len(nsec->rrs.rdata); + + return kr_nsec_children_in_zone_check(bm, bm_size); +} + +int kr_nsec_bitmap_nodata_check(const uint8_t *bm, uint16_t bm_size, uint16_t type, const knot_dname_t *owner) +{ + const int NO_PROOF = abs(ENOENT); + if (!bm || !owner) + return kr_error(EINVAL); + if (dnssec_nsec_bitmap_contains(bm, bm_size, type)) + return NO_PROOF; + + if (type != KNOT_RRTYPE_CNAME + && dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_CNAME)) { + return NO_PROOF; + } + /* Special behavior around zone cuts. */ + switch (type) { + case KNOT_RRTYPE_DS: + /* Security feature: in case of DS also check for SOA + * non-existence to be more certain that we don't hold + * a child-side NSEC by some mistake (e.g. when forwarding). + * See RFC4035 5.2, next-to-last paragraph. + * This doesn't apply for root DS as it doesn't exist in DNS hierarchy. + */ + if (owner[0] != '\0' && dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_SOA)) + return NO_PROOF; + break; + case KNOT_RRTYPE_CNAME: + /* Exception from the `default` rule. It's perhaps disputable, + * but existence of CNAME at zone apex is not allowed, so we + * consider a parent-side record to be enough to prove non-existence. */ + break; + default: + /* Parent-side delegation record isn't authoritative for non-DS; + * see RFC6840 4.1. */ + if (dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_NS) + && !dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_SOA)) { + return NO_PROOF; + } + /* LATER(opt): perhaps short-circuit test if we repeat it here. */ + } + + return kr_ok(); +} + +/// Convenience wrapper for kr_nsec_bitmap_nodata_check() +static int no_data_response_check_rrtype(const knot_rrset_t *nsec, uint16_t type) +{ + if (kr_fails_assert(nsec && nsec->type == KNOT_RRTYPE_NSEC)) + return kr_error(EINVAL); + const uint8_t *bm = knot_nsec_bitmap(nsec->rrs.rdata); + uint16_t bm_size = knot_nsec_bitmap_len(nsec->rrs.rdata); + return kr_nsec_bitmap_nodata_check(bm, bm_size, type, nsec->owner); +} + +int kr_nsec_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *sname) +{ + const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id); + if (!sec || !sname) + return kr_error(EINVAL); + + for (unsigned i = 0; i < sec->count; ++i) { + const knot_rrset_t *rrset = knot_pkt_rr(sec, i); + if (rrset->type != KNOT_RRTYPE_NSEC) + continue; + if (nsec_covers(rrset, sname) == 0) + return kr_ok(); + } + + return kr_error(ENOENT); +} + +int kr_nsec_negative(const ranked_rr_array_t *rrrs, uint32_t qry_uid, + const knot_dname_t *sname, uint16_t stype) +{ + // We really only consider the (canonically) first NSEC in each RRset. + // Using same owner with differing content probably isn't useful for NSECs anyway. + // Many other parts of code do the same, too. + if (kr_fails_assert(rrrs && sname)) + return kr_error(EINVAL); + + // Terminology: https://datatracker.ietf.org/doc/html/rfc4592#section-3.3.1 + int clencl_labels = -1; // the label count of the closest encloser of sname + for (int i = rrrs->len - 1; i >= 0; --i) { // NSECs near the end typically + const knot_rrset_t *nsec = rrrs->at[i]->rr; + bool ok = rrrs->at[i]->qry_uid == qry_uid + && nsec->type == KNOT_RRTYPE_NSEC + && kr_rank_test(rrrs->at[i]->rank, KR_RANK_SECURE); + if (!ok) continue; + const int covers = nsec_covers(nsec, sname); + if (covers == abs(EEXIST) + && no_data_response_check_rrtype(nsec, stype) == 0) { + return PKT_NODATA; // proven NODATA by matching NSEC + } + if (covers != 0) continue; + + // We have to lower-case 'next' with libknot >= 2.7; see also RFC 6840 5.1. + // LATER(optim.): it's duplicate work with the nsec_covers() call. + knot_dname_t next[KNOT_DNAME_MAXLEN]; + int ret = knot_dname_to_wire(next, knot_nsec_next(nsec->rrs.rdata), sizeof(next)); + if (kr_fails_assert(ret >= 0)) + return kr_error(ret); + knot_dname_to_lower(next); + + clencl_labels = MAX(knot_dname_matched_labels(nsec->owner, sname), + knot_dname_matched_labels(sname, next)); + break; // reduce indentation again + } + + if (clencl_labels < 0) + return kr_error(ENOENT); + const int sname_labels = knot_dname_labels(sname, NULL); + if (sname_labels == clencl_labels) + return PKT_NODATA; // proven NODATA; sname is an empty non-terminal + + // Explicitly construct name for the corresponding source of synthesis. + knot_dname_t ssynth[KNOT_DNAME_MAXLEN + 2]; + ssynth[0] = 1; + ssynth[1] = '*'; + const knot_dname_t *clencl = sname; + for (int l = sname_labels; l > clencl_labels; --l) + clencl = knot_wire_next_label(clencl, NULL); + (void)!!knot_dname_store(&ssynth[2], clencl); + + // Try to (dis)prove the source of synthesis by a covering or matching NSEC. + for (int i = rrrs->len - 1; i >= 0; --i) { // NSECs near the end typically + const knot_rrset_t *nsec = rrrs->at[i]->rr; + bool ok = rrrs->at[i]->qry_uid == qry_uid + && nsec->type == KNOT_RRTYPE_NSEC + && kr_rank_test(rrrs->at[i]->rank, KR_RANK_SECURE); + if (!ok) continue; + const int covers = nsec_covers(nsec, ssynth); + if (covers == abs(EEXIST)) { + int ret = no_data_response_check_rrtype(nsec, stype); + if (ret == 0) return PKT_NODATA; // proven NODATA by wildcard NSEC + // TODO: also try expansion? Or at least a different return code? + } else if (covers == 0) { + return PKT_NXDOMAIN | PKT_NODATA; + } + } + return kr_error(ENOENT); +} + +int kr_nsec_ref_to_unsigned(const ranked_rr_array_t *rrrs, uint32_t qry_uid, + const knot_dname_t *sname) +{ + for (int i = rrrs->len - 1; i >= 0; --i) { // NSECs near the end typically + const knot_rrset_t *nsec = rrrs->at[i]->rr; + bool ok = rrrs->at[i]->qry_uid == qry_uid + && nsec->type == KNOT_RRTYPE_NSEC + && kr_rank_test(rrrs->at[i]->rank, KR_RANK_SECURE) + // avoid any possibility of getting tricked in deeper zones + && knot_dname_in_bailiwick(sname, nsec->owner) >= 0; + if (!ok) continue; + + kr_assert(nsec->rrs.rdata); + const uint8_t *bm = knot_nsec_bitmap(nsec->rrs.rdata); + uint16_t bm_size = knot_nsec_bitmap_len(nsec->rrs.rdata); + ok = ok && dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_NS) + && !dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_DS) + && !dnssec_nsec_bitmap_contains(bm, bm_size, KNOT_RRTYPE_SOA); + if (ok) return kr_ok(); + } + return kr_error(DNSSEC_NOT_FOUND); +} + +int kr_nsec_matches_name_and_type(const knot_rrset_t *nsec, + const knot_dname_t *name, uint16_t type) +{ + /* It's not secure enough to just check a single bit for (some) other types, + * but we (currently) only use this API for NS. See RFC 6840 sec. 4. */ + if (kr_fails_assert(type == KNOT_RRTYPE_NS && nsec && nsec->rrs.rdata && name)) + return kr_error(EINVAL); + if (!knot_dname_is_equal(nsec->owner, name)) + return kr_error(ENOENT); + const uint8_t *bm = knot_nsec_bitmap(nsec->rrs.rdata); + uint16_t bm_size = knot_nsec_bitmap_len(nsec->rrs.rdata); + if (dnssec_nsec_bitmap_contains(bm, bm_size, type)) { + return kr_ok(); + } else { + return kr_error(ENOENT); + } +} diff --git a/lib/dnssec/nsec.h b/lib/dnssec/nsec.h new file mode 100644 index 0000000..a173fa5 --- /dev/null +++ b/lib/dnssec/nsec.h @@ -0,0 +1,69 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#pragma once + +#include <libknot/packet/pkt.h> + +#include "lib/layer/iterate.h" + +/** + * Check bitmap that child names are contained in the same zone. + * @note see RFC6840 4.1. + * @param bm Bitmap from NSEC or NSEC3. + * @param bm_size Bitmap size. + * @return 0 if they are, >0 if not (abs(ENOENT)), <0 on error. + */ +int kr_nsec_children_in_zone_check(const uint8_t *bm, uint16_t bm_size); + +/** + * Check an NSEC or NSEC3 bitmap for NODATA for a type. + * @param bm Bitmap. + * @param bm_size Bitmap size. + * @param type RR type to check. + * @param owner NSEC record owner. + * @note This includes special checks for zone cuts, e.g. from RFC 6840 sec. 4. + * @return 0, abs(ENOENT) (no proof), kr_error(EINVAL) + */ +int kr_nsec_bitmap_nodata_check(const uint8_t *bm, uint16_t bm_size, uint16_t type, const knot_dname_t *owner); + +/** + * Wildcard answer response check (RFC4035 3.1.3.3). + * @param pkt Packet structure to be processed. + * @param section_id Packet section to be processed. + * @param sname Name to be checked. + * @return 0 or error code. + */ +int kr_nsec_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *sname); + +/** + * Search for a negative proof for sname+stype among validated NSECs. + * + * @param rrrs list of RRs to search; typically kr_request::auth_selected + * @param qry_uid only consider NSECs from this packet, for better efficiency + * @return negative error code, or PKT_NXDOMAIN | PKT_NODATA (both for NXDOMAIN) + */ +int kr_nsec_negative(const ranked_rr_array_t *rrrs, uint32_t qry_uid, + const knot_dname_t *sname, uint16_t stype); + +/** + * Referral to unsigned subzone check (RFC4035 5.2). + * + * @param rrrs list of RRs to search; typically kr_request::auth_selected + * @param qry_uid only consider NSECs from this packet, for better efficiency + * @return 0 or negative error code, in particular DNSSEC_NOT_FOUND + */ +int kr_nsec_ref_to_unsigned(const ranked_rr_array_t *rrrs, uint32_t qry_uid, + const knot_dname_t *sname); + +/** + * Checks whether supplied NSEC RR matches the supplied name and type. + * @param nsec NSEC RR. + * @param name Name to be checked. + * @param type Type to be checked. Only use with NS! TODO (+copy&paste NSEC3) + * @return 0 or error code. + */ +int kr_nsec_matches_name_and_type(const knot_rrset_t *nsec, + const knot_dname_t *name, uint16_t type); diff --git a/lib/dnssec/nsec3.c b/lib/dnssec/nsec3.c new file mode 100644 index 0000000..037d5bd --- /dev/null +++ b/lib/dnssec/nsec3.c @@ -0,0 +1,722 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#include <string.h> + +#include <libdnssec/binary.h> +#include <libdnssec/error.h> +#include <libdnssec/nsec.h> +#include <libknot/descriptor.h> +#include <contrib/base32hex.h> +#include <libknot/rrset.h> +#include <libknot/rrtype/nsec3.h> + +#include "lib/defines.h" +#include "lib/dnssec/nsec.h" +#include "lib/dnssec/nsec3.h" +#include "lib/utils.h" + +#define OPT_OUT_BIT 0x01 + +//#define FLG_CLOSEST_ENCLOSER (1 << 0) +#define FLG_CLOSEST_PROVABLE_ENCLOSER (1 << 1) +#define FLG_NAME_COVERED (1 << 2) +#define FLG_NAME_MATCHED (1 << 3) +#define FLG_TYPE_BIT_MISSING (1 << 4) +#define FLG_CNAME_BIT_MISSING (1 << 5) + +/** + * Obtains NSEC3 parameters from RR. + * @param params NSEC3 parameters structure to be set. + * @param nsec3 NSEC3 RR containing the parameters. + * @return 0 or error code. + */ +static int nsec3_parameters(dnssec_nsec3_params_t *params, const knot_rrset_t *nsec3) +{ + if (kr_fails_assert(params && nsec3)) + return kr_error(EINVAL); + + const knot_rdata_t *rr = knot_rdataset_at(&nsec3->rrs, 0); + if (kr_fails_assert(rr)) + return kr_error(EINVAL); + + /* Every NSEC3 RR contains data from NSEC3PARAMS. */ + const size_t SALT_OFFSET = 5; /* First 5 octets contain { Alg, Flags, Iterations, Salt length } */ + dnssec_binary_t rdata = { + .size = SALT_OFFSET + (size_t)knot_nsec3_salt_len(nsec3->rrs.rdata), + .data = /*const-cast*/(uint8_t *)rr->data, + }; + if (rdata.size > rr->len) + return kr_error(EMSGSIZE); + + int ret = dnssec_nsec3_params_from_rdata(params, &rdata); + if (ret != DNSSEC_EOK) + return kr_error(EINVAL); + + return kr_ok(); +} + +/** + * Computes a hash of a given domain name. + * @param hash Resulting hash, must be freed. + * @param params NSEC3 parameters. + * @param name Domain name to be hashed. + * @return 0 or error code. + */ +static int hash_name(dnssec_binary_t *hash, const dnssec_nsec3_params_t *params, + const knot_dname_t *name) +{ + if (kr_fails_assert(hash && params)) + return kr_error(EINVAL); + if (!name) + return kr_error(EINVAL); + if (kr_fails_assert(params->iterations <= KR_NSEC3_MAX_ITERATIONS)) { + /* This if is mainly defensive; it shouldn't happen. */ + return kr_error(EINVAL); + } + + dnssec_binary_t dname = { + .size = knot_dname_size(name), + .data = (uint8_t *) name, + }; + + int ret = dnssec_nsec3_hash(&dname, params, hash); + if (ret != DNSSEC_EOK) { + return kr_error(EINVAL); + } + + return kr_ok(); +} + +/** + * Read hash from NSEC3 owner name and store its binary form. + * @param hash Buffer to be written. + * @param max_hash_size Maximal has size. + * @param nsec3 NSEC3 RR. + * @return 0 or error code. + */ +static int read_owner_hash(dnssec_binary_t *hash, size_t max_hash_size, const knot_rrset_t *nsec3) +{ + if (kr_fails_assert(hash && nsec3 && hash->data)) + return kr_error(EINVAL); + + int32_t ret = base32hex_decode(nsec3->owner + 1, nsec3->owner[0], hash->data, max_hash_size); + if (ret < 0) + return kr_error(EILSEQ); + hash->size = ret; + + return kr_ok(); +} + +#define MAX_HASH_BYTES 64 +/** + * Closest (provable) encloser match (RFC5155 7.2.1, bullet 1). + * @param flags Flags to be set according to check outcome. + * @param nsec3 NSEC3 RR. + * @param name Name to be checked. + * @param skipped Number of skipped labels to find closest (provable) match. + * @return 0 or error code. + */ +static int closest_encloser_match(int *flags, const knot_rrset_t *nsec3, + const knot_dname_t *name, unsigned *skipped) +{ + if (kr_fails_assert(flags && nsec3 && name && skipped)) + return kr_error(EINVAL); + + uint8_t hash_data[MAX_HASH_BYTES] = {0, }; + dnssec_binary_t owner_hash = { 0, hash_data }; + dnssec_nsec3_params_t params = { 0, }; + dnssec_binary_t name_hash = { 0, }; + + int ret = read_owner_hash(&owner_hash, MAX_HASH_BYTES, nsec3); + if (ret != 0) + goto fail; + + ret = nsec3_parameters(¶ms, nsec3); + if (ret != 0) + goto fail; + + /* Root label has no encloser */ + if (!name[0]) { + ret = kr_error(ENOENT); + goto fail; + } + + const knot_dname_t *encloser = knot_wire_next_label(name, NULL); + *skipped = 1; + + while(encloser) { + ret = hash_name(&name_hash, ¶ms, encloser); + if (ret != 0) + goto fail; + + if ((owner_hash.size == name_hash.size) && + (memcmp(owner_hash.data, name_hash.data, owner_hash.size) == 0)) { + dnssec_binary_free(&name_hash); + *flags |= FLG_CLOSEST_PROVABLE_ENCLOSER; + break; + } + + dnssec_binary_free(&name_hash); + + if (!encloser[0]) + break; + encloser = knot_wire_next_label(encloser, NULL); + ++(*skipped); + } + + ret = kr_ok(); + +fail: + if (params.salt.data) + dnssec_nsec3_params_free(¶ms); + if (name_hash.data) + dnssec_binary_free(&name_hash); + return ret; +} + +/** + * Checks whether NSEC3 RR covers the supplied name (RFC5155 7.2.1, bullet 2). + * @param flags Flags to be set according to check outcome. + * @param nsec3 NSEC3 RR. + * @param name Name to be checked. + * @return 0 or error code. + */ +static int covers_name(int *flags, const knot_rrset_t *nsec3, const knot_dname_t *name) +{ + if (kr_fails_assert(flags && nsec3 && name)) + return kr_error(EINVAL); + + uint8_t hash_data[MAX_HASH_BYTES] = { 0, }; + dnssec_binary_t owner_hash = { 0, hash_data }; + dnssec_nsec3_params_t params = { 0, }; + dnssec_binary_t name_hash = { 0, }; + + int ret = read_owner_hash(&owner_hash, MAX_HASH_BYTES, nsec3); + if (ret != 0) + goto fail; + + ret = nsec3_parameters(¶ms, nsec3); + if (ret != 0) + goto fail; + + ret = hash_name(&name_hash, ¶ms, name); + if (ret != 0) + goto fail; + + uint8_t next_size = knot_nsec3_next_len(nsec3->rrs.rdata); + const uint8_t *next_hash = knot_nsec3_next(nsec3->rrs.rdata); + + if ((next_size > 0) && (owner_hash.size == next_size) && (name_hash.size == next_size)) { + /* All hash lengths must be same. */ + const uint8_t *ownerd = owner_hash.data; + const uint8_t *nextd = next_hash; + int covered = 0; + int greater_then_owner = (memcmp(ownerd, name_hash.data, next_size) < 0); + int less_then_next = (memcmp(name_hash.data, nextd, next_size) < 0); + if (memcmp(ownerd, nextd, next_size) < 0) { + /* + * 0 (...) owner ... next (...) MAX + * ^ + * name + * ==> + * (owner < name) && (name < next) + */ + covered = ((greater_then_owner) && (less_then_next)); + } else { + /* + * owner ... MAX, 0 ... next + * ^ ^ ^ + * name name name + * => + * (owner < name) || (name < next) + */ + covered = ((greater_then_owner) || (less_then_next)); + } + + if (covered) { + *flags |= FLG_NAME_COVERED; + + uint8_t nsec3_flags = knot_nsec3_flags(nsec3->rrs.rdata); + if (nsec3_flags & ~OPT_OUT_BIT) { + /* RFC5155 3.1.2 */ + ret = kr_error(EINVAL); + } else { + ret = kr_ok(); + } + } + } + +fail: + if (params.salt.data) + dnssec_nsec3_params_free(¶ms); + if (name_hash.data) + dnssec_binary_free(&name_hash); + return ret; +} + +/** + * Checks whether NSEC3 RR has the opt-out bit set. + * @param flags Flags to be set according to check outcome. + * @param nsec3 NSEC3 RR. + * @param name Name to be checked. + * @return 0 or error code. + */ +static bool has_optout(const knot_rrset_t *nsec3) +{ + if (!nsec3) + return false; + + uint8_t nsec3_flags = knot_nsec3_flags(nsec3->rrs.rdata); + if (nsec3_flags & ~OPT_OUT_BIT) { + /* RFC5155 3.1.2 */ + return false; + } + + return nsec3_flags & OPT_OUT_BIT; +} + +/** + * Checks whether NSEC3 RR matches the supplied name. + * @param flags Flags to be set according to check outcome. + * @param nsec3 NSEC3 RR. + * @param name Name to be checked. + * @return 0 if matching, >0 if not (abs(ENOENT)), or error code (<0). + */ +static int matches_name(const knot_rrset_t *nsec3, const knot_dname_t *name) +{ + if (kr_fails_assert(nsec3 && name)) + return kr_error(EINVAL); + + uint8_t hash_data[MAX_HASH_BYTES] = { 0, }; + dnssec_binary_t owner_hash = { 0, hash_data }; + dnssec_nsec3_params_t params = { 0, }; + dnssec_binary_t name_hash = { 0, }; + + int ret = read_owner_hash(&owner_hash, MAX_HASH_BYTES, nsec3); + if (ret != 0) + goto fail; + + ret = nsec3_parameters(¶ms, nsec3); + if (ret != 0) + goto fail; + + ret = hash_name(&name_hash, ¶ms, name); + if (ret != 0) + goto fail; + + if ((owner_hash.size == name_hash.size) && + (memcmp(owner_hash.data, name_hash.data, owner_hash.size) == 0)) { + ret = kr_ok(); + } else { + ret = abs(ENOENT); + } + +fail: + if (params.salt.data) + dnssec_nsec3_params_free(¶ms); + if (name_hash.data) + dnssec_binary_free(&name_hash); + return ret; +} +#undef MAX_HASH_BYTES + +/** + * Prepends an asterisk label to given name. + * + * @param tgt Target buffer to write domain name into. + * @param name Name to be added to the asterisk. + * @return Size of the resulting name or error code. + */ +static int prepend_asterisk(uint8_t *tgt, size_t maxlen, const knot_dname_t *name) +{ + if (kr_fails_assert(maxlen >= 3)) + return kr_error(EINVAL); + memcpy(tgt, "\1*", 3); + return knot_dname_to_wire(tgt + 2, name, maxlen - 2); +} + +/** + * Closest encloser proof (RFC5155 7.2.1). + * @note No RRSIGs are validated. + * @param pkt Packet structure to be processed. + * @param section_id Packet section to be processed. + * @param sname Name to be checked. + * @param encloser_name Returned matching encloser name, if found. + * @param matching_encloser_nsec3 Pointer to matching encloser NSEC RRSet. + * @param covering_next_nsec3 Pointer to covering next closer NSEC3 RRSet. + * @return 0 or error code. + */ +static int closest_encloser_proof(const knot_pkt_t *pkt, + knot_section_t section_id, + const knot_dname_t *sname, + const knot_dname_t **encloser_name, + const knot_rrset_t **matching_encloser_nsec3, + const knot_rrset_t **covering_next_nsec3) +{ + const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id); + if (!sec || !sname) + return kr_error(EINVAL); + + const knot_rrset_t *matching = NULL; + const knot_rrset_t *covering = NULL; + + int flags = 0; + const knot_dname_t *next_closer = NULL; + for (unsigned i = 0; i < sec->count; ++i) { + const knot_rrset_t *rrset = knot_pkt_rr(sec, i); + if (rrset->type != KNOT_RRTYPE_NSEC3) + continue; + /* Also skip the NSEC3-to-match an ancestor of sname if it's + * a parent-side delegation, as that would mean the owner + * does not really exist (authoritatively in this zone, + * even in case of opt-out). + */ + const uint8_t *bm = knot_nsec3_bitmap(rrset->rrs.rdata); + uint16_t bm_size = knot_nsec3_bitmap_len(rrset->rrs.rdata); + if (kr_nsec_children_in_zone_check(bm, bm_size) != 0) + continue; /* no fatal errors from bad RRs */ + /* Match the NSEC3 to sname or one of its ancestors. */ + unsigned skipped = 0; + flags = 0; + int ret = closest_encloser_match(&flags, rrset, sname, &skipped); + if (ret != 0) + return ret; + if (!(flags & FLG_CLOSEST_PROVABLE_ENCLOSER)) + continue; + matching = rrset; + /* Construct the next closer name and try to cover it. */ + --skipped; + next_closer = sname; + for (unsigned j = 0; j < skipped; ++j) { + if (kr_fails_assert(next_closer[0])) + return kr_error(EINVAL); + next_closer = knot_wire_next_label(next_closer, NULL); + } + for (unsigned j = 0; j < sec->count; ++j) { + const knot_rrset_t *rrset_j = knot_pkt_rr(sec, j); + if (rrset_j->type != KNOT_RRTYPE_NSEC3) + continue; + ret = covers_name(&flags, rrset_j, next_closer); + if (ret != 0) + return ret; + if (flags & FLG_NAME_COVERED) { + covering = rrset_j; + break; + } + } + if (flags & FLG_NAME_COVERED) + break; + flags = 0; // + } + + if ((flags & FLG_CLOSEST_PROVABLE_ENCLOSER) && (flags & FLG_NAME_COVERED) && next_closer) { + if (encloser_name && next_closer[0]) + *encloser_name = knot_wire_next_label(next_closer, NULL); + if (matching_encloser_nsec3) + *matching_encloser_nsec3 = matching; + if (covering_next_nsec3) + *covering_next_nsec3 = covering; + return kr_ok(); + } + + return kr_error(ENOENT); +} + +/** + * Check whether any NSEC3 RR covers a wildcard RR at the closer encloser. + * @param pkt Packet structure to be processed. + * @param section_id Packet section to be processed. + * @param encloser Closest (provable) encloser domain name. + * @return 0 or error code: + * KNOT_ERANGE - NSEC3 RR (that covers a wildcard) + * has been found, but has opt-out flag set; + * otherwise - error. + */ +static int covers_closest_encloser_wildcard(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *encloser) +{ + const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id); + if (!sec || !encloser) + return kr_error(EINVAL); + + uint8_t wildcard[KNOT_DNAME_MAXLEN]; + wildcard[0] = 1; + wildcard[1] = '*'; + int encloser_len = knot_dname_size(encloser); + if (encloser_len < 0) + return encloser_len; + memcpy(wildcard + 2, encloser, encloser_len); + + int flags = 0; + for (unsigned i = 0; i < sec->count; ++i) { + const knot_rrset_t *rrset = knot_pkt_rr(sec, i); + if (rrset->type != KNOT_RRTYPE_NSEC3) + continue; + int ret = covers_name(&flags, rrset, wildcard); + if (ret != 0) + return ret; + if (flags & FLG_NAME_COVERED) { + return has_optout(rrset) ? + kr_error(KNOT_ERANGE) : kr_ok(); + } + } + + return kr_error(ENOENT); +} + +int kr_nsec3_name_error_response_check(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *sname) +{ + const knot_dname_t *encloser = NULL; + const knot_rrset_t *covering_next_nsec3 = NULL; + int ret = closest_encloser_proof(pkt, section_id, sname, + &encloser, NULL, &covering_next_nsec3); + if (ret != 0) + return ret; + ret = covers_closest_encloser_wildcard(pkt, section_id, encloser); + if (ret != 0) { + /* OK, but NSEC3 for wildcard at encloser has opt-out; + * or error */ + return ret; + } + /* Closest encloser proof is OK and + * NSEC3 for wildcard has been found and optout flag is not set. + * Now check if NSEC3 that covers next closer name has opt-out. */ + return has_optout(covering_next_nsec3) ? + kr_error(KNOT_ERANGE) : kr_ok(); +} + +/** + * Search the packet section for a matching NSEC3 with nodata-proving bitmap. + * @param pkt Packet structure to be processed. + * @param section_id Packet section to be processed. + * @param sname Name to be checked. + * @param stype Type to be checked. + * @return 0 or error code. + * @note This does NOT check the opt-out case if type is DS; + * see RFC 5155 8.6. + */ +static int nodata_find(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *name, const uint16_t type) +{ + const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id); + if (!sec || !name) + return kr_error(EINVAL); + + for (unsigned i = 0; i < sec->count; ++i) { + const knot_rrset_t *nsec3 = knot_pkt_rr(sec, i); + /* Records causing any errors are simply skipped. */ + if (nsec3->type != KNOT_RRTYPE_NSEC3 + || matches_name(nsec3, name) != kr_ok()) { + continue; + /* LATER(optim.): we repeatedly recompute the hash of `name` */ + } + + const uint8_t *bm = knot_nsec3_bitmap(nsec3->rrs.rdata); + uint16_t bm_size = knot_nsec3_bitmap_len(nsec3->rrs.rdata); + if (kr_nsec_bitmap_nodata_check(bm, bm_size, type, nsec3->owner) == kr_ok()) + return kr_ok(); + } + + return kr_error(ENOENT); +} + +/** + * Check whether NSEC3 RR matches a wildcard at the closest encloser and has given type bit missing. + * @param pkt Packet structure to be processed. + * @param section_id Packet section to be processed. + * @param encloser Closest (provable) encloser domain name. + * @param stype Type to be checked. + * @return 0 or error code. + */ +static int matches_closest_encloser_wildcard(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *encloser, uint16_t stype) +{ + const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id); + if (!sec || !encloser) + return kr_error(EINVAL); + + uint8_t wildcard[KNOT_DNAME_MAXLEN]; /**< the source of synthesis */ + int ret = prepend_asterisk(wildcard, sizeof(wildcard), encloser); + if (ret < 0) + return ret; + kr_require(ret >= 3); + return nodata_find(pkt, section_id, wildcard, stype); +} + +int kr_nsec3_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *sname, int trim_to_next) +{ + const knot_pktsection_t *sec = knot_pkt_section(pkt, section_id); + if (!sec || !sname) + return kr_error(EINVAL); + + /* Compute the next closer name. */ + for (int i = 0; i < trim_to_next; ++i) { + if (kr_fails_assert(sname[0])) + return kr_error(EINVAL); + sname = knot_wire_next_label(sname, NULL); + } + + int flags = 0; + for (unsigned i = 0; i < sec->count; ++i) { + const knot_rrset_t *rrset = knot_pkt_rr(sec, i); + if (rrset->type != KNOT_RRTYPE_NSEC3) + continue; + if (knot_nsec3_iters(rrset->rrs.rdata) > KR_NSEC3_MAX_ITERATIONS) { + /* Avoid hashing with too many iterations. + * If we get here, the `sname` wildcard probably ends up bogus, + * but it gets downgraded to KR_RANK_INSECURE when validator + * gets to verifying one of these over-limit NSEC3 RRs. */ + continue; + } + int ret = covers_name(&flags, rrset, sname); + if (ret != 0) + return ret; + if (flags & FLG_NAME_COVERED) { + return has_optout(rrset) ? + kr_error(KNOT_ERANGE) : kr_ok(); + } + } + + return kr_error(ENOENT); +} + + +int kr_nsec3_no_data(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *sname, uint16_t stype) +{ + /* DS record may be also matched by an existing NSEC3 RR. */ + int ret = nodata_find(pkt, section_id, sname, stype); + if (ret == 0) { + /* Satisfies RFC5155 8.5 and 8.6, both first paragraph. */ + return ret; + } + + /* Find closest provable encloser. */ + const knot_dname_t *encloser_name = NULL; + const knot_rrset_t *covering_next_nsec3 = NULL; + ret = closest_encloser_proof(pkt, section_id, sname, &encloser_name, + NULL, &covering_next_nsec3); + if (ret != 0) + return ret; + + if (kr_fails_assert(encloser_name && covering_next_nsec3)) + return kr_error(EFAULT); + ret = matches_closest_encloser_wildcard(pkt, section_id, + encloser_name, stype); + if (ret == 0) { + /* Satisfies RFC5155 8.7 */ + if (has_optout(covering_next_nsec3)) { + /* Opt-out is detected. + * Despite the fact that all records + * in the packet can be properly signed, + * AD bit must not be set due to rfc5155 9.2. + * Return appropriate code to the caller */ + ret = kr_error(KNOT_ERANGE); + } + return ret; + } + + if (!has_optout(covering_next_nsec3)) { + /* Bogus */ + ret = kr_error(ENOENT); + } else { + /* + * Satisfies RFC5155 8.6 (QTYPE == DS), 2nd paragraph. + * Also satisfies ERRATA 3441 8.5 (QTYPE != DS), 3rd paragraph. + * - (wildcard) empty nonterminal + * derived from insecure delegation. + * Denial of existence can not be proven. + * Set error code to proceed insecure. + */ + ret = kr_error(KNOT_ERANGE); + } + + return ret; +} + +int kr_nsec3_ref_to_unsigned(const knot_pkt_t *pkt) +{ + const knot_pktsection_t *sec = knot_pkt_section(pkt, KNOT_AUTHORITY); + if (!sec) + return kr_error(EINVAL); + for (unsigned i = 0; i < sec->count; ++i) { + const knot_rrset_t *ns = knot_pkt_rr(sec, i); + if (ns->type == KNOT_RRTYPE_DS) + return kr_error(EEXIST); + if (ns->type != KNOT_RRTYPE_NS) + continue; + + bool nsec3_found = false; + for (unsigned j = 0; j < sec->count; ++j) { + const knot_rrset_t *nsec3 = knot_pkt_rr(sec, j); + if (nsec3->type == KNOT_RRTYPE_DS) + return kr_error(EEXIST); + if (nsec3->type != KNOT_RRTYPE_NSEC3) + continue; + nsec3_found = true; + /* nsec3 found, check if owner name matches the delegation name. + * Just skip in case of *any* errors. */ + if (matches_name(nsec3, ns->owner) != kr_ok()) + continue; + + const uint8_t *bm = knot_nsec3_bitmap(nsec3->rrs.rdata); + uint16_t bm_size = knot_nsec3_bitmap_len(nsec3->rrs.rdata); + if (!bm) + return kr_error(EINVAL); + if (dnssec_nsec_bitmap_contains(bm, bm_size, + KNOT_RRTYPE_NS) && + !dnssec_nsec_bitmap_contains(bm, bm_size, + KNOT_RRTYPE_DS) && + !dnssec_nsec_bitmap_contains(bm, bm_size, + KNOT_RRTYPE_SOA)) { + /* Satisfies rfc5155, 8.9. paragraph 2 */ + return kr_ok(); + } + } + if (!nsec3_found) + return kr_error(DNSSEC_NOT_FOUND); + /* nsec3 that matches the delegation was not found. + * Check rfc5155, 8.9. paragraph 4. + * Find closest provable encloser. + */ + const knot_dname_t *encloser_name = NULL; + const knot_rrset_t *covering_next_nsec3 = NULL; + int ret = closest_encloser_proof(pkt, KNOT_AUTHORITY, ns->owner, + &encloser_name, NULL, &covering_next_nsec3); + if (ret != 0) + return kr_error(EINVAL); + + if (has_optout(covering_next_nsec3)) { + return kr_error(KNOT_ERANGE); + } else { + return kr_error(EINVAL); + } + } + return kr_error(EINVAL); +} + +int kr_nsec3_matches_name_and_type(const knot_rrset_t *nsec3, + const knot_dname_t *name, uint16_t type) +{ + /* It's not secure enough to just check a single bit for (some) other types, + * but we don't (currently) only use this API for NS. See RFC 6840 sec. 4. + */ + if (kr_fails_assert(type == KNOT_RRTYPE_NS)) + return kr_error(EINVAL); + int ret = matches_name(nsec3, name); + if (ret) + return kr_error(ret); + const uint8_t *bm = knot_nsec3_bitmap(nsec3->rrs.rdata); + uint16_t bm_size = knot_nsec3_bitmap_len(nsec3->rrs.rdata); + if (!bm) + return kr_error(EINVAL); + if (dnssec_nsec_bitmap_contains(bm, bm_size, type)) { + return kr_ok(); + } else { + return kr_error(ENOENT); + } +} diff --git a/lib/dnssec/nsec3.h b/lib/dnssec/nsec3.h new file mode 100644 index 0000000..eb0bd39 --- /dev/null +++ b/lib/dnssec/nsec3.h @@ -0,0 +1,83 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#pragma once + +#include <libknot/packet/pkt.h> + +/** High numbers in NSEC3 iterations don't really help security + * + * ...so we avoid doing all the work. The value is a current compromise; + * zones shooting over get downgraded to insecure status. + * + * Original restriction wasn't that strict: + https://datatracker.ietf.org/doc/html/rfc5155#section-10.3 + * but there is discussion about officially lowering the limits: + https://tools.ietf.org/id/draft-hardaker-dnsop-nsec3-guidance-02.html#section-2.3 + */ +#define KR_NSEC3_MAX_ITERATIONS 150 + +/** + * Name error response check (RFC5155 7.2.2). + * @note No RRSIGs are validated. + * @param pkt Packet structure to be processed. + * @param section_id Packet section to be processed. + * @param sname Name to be checked. + * @return 0 or error code. + */ +int kr_nsec3_name_error_response_check(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *sname); + +/** + * Wildcard answer response check (RFC5155 7.2.6). + * @param pkt Packet structure to be processed. + * @param section_id Packet section to be processed. + * @param sname Name to be checked. + * @param trim_to_next Number of labels to remove to obtain next closer name. + * @return 0 or error code: + * KNOT_ERANGE - NSEC3 RR that covers a wildcard + * has been found, but has opt-out flag set; + * otherwise - error. + * Records over KR_NSEC3_MAX_ITERATIONS are skipped, so you probably get kr_error(ENOENT). + */ +int kr_nsec3_wildcard_answer_response_check(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *sname, int trim_to_next); + +/** + * Authenticated denial of existence according to RFC5155 8.5 and 8.7. + * @note No RRSIGs are validated. + * @param pkt Packet structure to be processed. + * @param section_id Packet section to be processed. + * @param sname Queried domain name. + * @param stype Queried type. + * @return 0 or error code: + * DNSSEC_NOT_FOUND - neither ds nor nsec records + * were not found. + * KNOT_ERANGE - denial of existence can't be proven + * due to opt-out, otherwise - bogus. + */ +int kr_nsec3_no_data(const knot_pkt_t *pkt, knot_section_t section_id, + const knot_dname_t *sname, uint16_t stype); + +/** + * Referral to unsigned subzone check (RFC5155 8.9). + * @note No RRSIGs are validated. + * @param pkt Packet structure to be processed. + * @return 0 or error code: + * KNOT_ERANGE - denial of existence can't be proven + * due to opt-out. + * EEXIST - ds record was found. + * EINVAL - bogus. + */ +int kr_nsec3_ref_to_unsigned(const knot_pkt_t *pkt); + +/** + * Checks whether supplied NSEC3 RR matches the supplied name and NS type. + * @param nsec3 NSEC3 RR. + * @param name Name to be checked. + * @param type Type to be checked. Only use with NS! TODO + * @return 0 or error code. + */ +int kr_nsec3_matches_name_and_type(const knot_rrset_t *nsec3, + const knot_dname_t *name, uint16_t type); diff --git a/lib/dnssec/signature.c b/lib/dnssec/signature.c new file mode 100644 index 0000000..aadb5cb --- /dev/null +++ b/lib/dnssec/signature.c @@ -0,0 +1,304 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#include <arpa/inet.h> +#include <string.h> + +#include <libdnssec/error.h> +#include <libdnssec/key.h> +#include <libdnssec/sign.h> +#include <libknot/descriptor.h> +#include <libknot/packet/rrset-wire.h> +#include <libknot/packet/wire.h> +#include <libknot/rrset.h> +#include <libknot/rrtype/rrsig.h> +#include <libknot/rrtype/ds.h> +#include <libknot/wire.h> + +#include "lib/defines.h" +#include "lib/utils.h" +#include "lib/dnssec/signature.h" + +static int authenticate_ds(const dnssec_key_t *key, dnssec_binary_t *ds_rdata, uint8_t digest_type) +{ + /* Compute DS RDATA from the DNSKEY. */ + dnssec_binary_t computed_ds = { 0, }; + int ret = dnssec_key_create_ds(key, digest_type, &computed_ds); + if (ret != DNSSEC_EOK) + goto fail; + + /* DS records contain algorithm, key tag and the digest. + * Therefore the comparison of the two DS is sufficient. + */ + ret = (ds_rdata->size == computed_ds.size) && + (memcmp(ds_rdata->data, computed_ds.data, ds_rdata->size) == 0); + ret = ret ? kr_ok() : kr_error(ENOENT); + +fail: + dnssec_binary_free(&computed_ds); + return kr_error(ret); +} + +int kr_authenticate_referral(const knot_rrset_t *ref, const dnssec_key_t *key) +{ + if (kr_fails_assert(ref && key)) + return kr_error(EINVAL); + if (ref->type != KNOT_RRTYPE_DS) + return kr_error(EINVAL); + + /* Determine whether to ignore SHA1 digests, because: + https://datatracker.ietf.org/doc/html/rfc4509#section-3 + * Now, the RFCs seem to only mention SHA1 and SHA256 (e.g. no SHA384), + * but the most natural extension is to make any other algorithm trump SHA1. + * (Note that the old GOST version is already unsupported by libdnssec.) */ + bool skip_sha1 = false; + knot_rdata_t *rd = ref->rrs.rdata; + for (int i = 0; i < ref->rrs.count; ++i, rd = knot_rdataset_next(rd)) { + const uint8_t algo = knot_ds_digest_type(rd); + if (algo != DNSSEC_KEY_DIGEST_SHA1 && dnssec_algorithm_digest_support(algo)) { + skip_sha1 = true; + break; + } + } + /* But otherwise try all possible DS records. */ + int ret = 0; + rd = ref->rrs.rdata; + for (int i = 0; i < ref->rrs.count; ++i, rd = knot_rdataset_next(rd)) { + const uint8_t algo = knot_ds_digest_type(rd); + if (skip_sha1 && algo == DNSSEC_KEY_DIGEST_SHA1) + continue; + dnssec_binary_t ds_rdata = { + .size = rd->len, + .data = rd->data + }; + ret = authenticate_ds(key, &ds_rdata, algo); + if (ret == 0) /* Found a good DS */ + return kr_ok(); + } + + return kr_error(ret); +} + +/** + * Adjust TTL in wire format. + * @param wire RR Set in wire format. + * @param wire_size Size of the wire data portion. + * @param new_ttl TTL value to be set for all RRs. + * @return 0 or error code. + */ +static int adjust_wire_ttl(uint8_t *wire, size_t wire_size, uint32_t new_ttl) +{ + if (kr_fails_assert(wire)) + return kr_error(EINVAL); + static_assert(sizeof(uint16_t) == 2, "uint16_t must be exactly 2 bytes"); + static_assert(sizeof(uint32_t) == 4, "uint32_t must be exactly 4 bytes"); + uint16_t rdlen; + + int ret; + + new_ttl = htonl(new_ttl); + + size_t i = 0; + /* RR wire format in RFC1035 3.2.1 */ + while(i < wire_size) { + ret = knot_dname_size(wire + i); + if (ret < 0) + return ret; + i += ret + 4; + memcpy(wire + i, &new_ttl, sizeof(uint32_t)); + i += sizeof(uint32_t); + + memcpy(&rdlen, wire + i, sizeof(uint16_t)); + rdlen = ntohs(rdlen); + i += sizeof(uint16_t) + rdlen; + + if (kr_fails_assert(i <= wire_size)) + return kr_error(EINVAL); + } + + return kr_ok(); +} + +/*! + * \brief Add RRSIG RDATA without signature to signing context. + * + * Requires signer name in RDATA in canonical form. + * + * \param ctx Signing context. + * \param rdata Pointer to RRSIG RDATA. + * + * \return Error code, KNOT_EOK if successful. + */ +#define RRSIG_RDATA_SIGNER_OFFSET 18 +static int sign_ctx_add_self(dnssec_sign_ctx_t *ctx, const uint8_t *rdata) +{ + if (kr_fails_assert(ctx && rdata)) + return kr_error(EINVAL); + + int result; + + // static header + + dnssec_binary_t header = { + .data = (uint8_t *)rdata, + .size = RRSIG_RDATA_SIGNER_OFFSET, + }; + + result = dnssec_sign_add(ctx, &header); + if (result != DNSSEC_EOK) + return result; + + // signer name + + const uint8_t *rdata_signer = rdata + RRSIG_RDATA_SIGNER_OFFSET; + dnssec_binary_t signer = { 0 }; + signer.data = knot_dname_copy(rdata_signer, NULL); + signer.size = knot_dname_size(signer.data); + + result = dnssec_sign_add(ctx, &signer); + free(signer.data); + + return result; +} +#undef RRSIG_RDATA_SIGNER_OFFSET + +/*! + * \brief Add covered RRs to signing context. + * + * Requires all DNAMEs in canonical form and all RRs ordered canonically. + * + * \param ctx Signing context. + * \param covered Covered RRs. + * + * \return Error code, KNOT_EOK if successful. + */ +static int sign_ctx_add_records(dnssec_sign_ctx_t *ctx, const knot_rrset_t *covered, + uint32_t orig_ttl, int trim_labels) +{ + if (!ctx || !covered || trim_labels < 0) + return kr_error(EINVAL); + + // huge block of rrsets can be optionally created + static uint8_t wire_buffer[KNOT_WIRE_MAX_PKTSIZE]; + int written = knot_rrset_to_wire(covered, wire_buffer, sizeof(wire_buffer), NULL); + if (written < 0) + return written; + + /* Set original ttl. */ + int ret = adjust_wire_ttl(wire_buffer, written, orig_ttl); + if (ret != 0) + return ret; + + if (!trim_labels) { + const dnssec_binary_t wire_binary = { + .size = written, + .data = wire_buffer + }; + return dnssec_sign_add(ctx, &wire_binary); + } + + /* RFC4035 5.3.2 + * Remove leftmost labels and replace them with '*.' + * for each RR in covered. + */ + uint8_t *beginp = wire_buffer; + for (uint16_t i = 0; i < covered->rrs.count; ++i) { + /* RR(i) = name | type | class | OrigTTL | RDATA length | RDATA */ + for (int j = 0; j < trim_labels; ++j) { + if (kr_fails_assert(beginp[0])) + return kr_error(EINVAL); + beginp = (uint8_t *) knot_wire_next_label(beginp, NULL); + if (kr_fails_assert(beginp)) + return kr_error(EFAULT); + } + *(--beginp) = '*'; + *(--beginp) = 1; + const size_t rdatalen_offset = knot_dname_size(beginp) + /* name */ + sizeof(uint16_t) + /* type */ + sizeof(uint16_t) + /* class */ + sizeof(uint32_t); /* OrigTTL */ + const uint8_t *rdatalen_ptr = beginp + rdatalen_offset; + const uint16_t rdata_size = knot_wire_read_u16(rdatalen_ptr); + const size_t rr_size = rdatalen_offset + + sizeof(uint16_t) + /* RDATA length */ + rdata_size; /* RDATA */ + const dnssec_binary_t wire_binary = { + .size = rr_size, + .data = beginp + }; + ret = dnssec_sign_add(ctx, &wire_binary); + if (ret != 0) + break; + beginp += rr_size; + } + return ret; +} + +/*! + * \brief Add all data covered by signature into signing context. + * + * RFC 4034: The signature covers RRSIG RDATA field (excluding the signature) + * and all matching RR records, which are ordered canonically. + * + * Requires all DNAMEs in canonical form and all RRs ordered canonically. + * + * \param ctx Signing context. + * \param rrsig_rdata RRSIG RDATA with populated fields except signature. + * \param covered Covered RRs. + * + * \return Error code, KNOT_EOK if successful. + */ +/* TODO -- Taken from knot/src/knot/dnssec/rrset-sign.c. Re-write for better fit needed. */ +static int sign_ctx_add_data(dnssec_sign_ctx_t *ctx, const uint8_t *rrsig_rdata, + const knot_rrset_t *covered, uint32_t orig_ttl, int trim_labels) +{ + int result = sign_ctx_add_self(ctx, rrsig_rdata); + if (result != KNOT_EOK) + return result; + + return sign_ctx_add_records(ctx, covered, orig_ttl, trim_labels); +} + +int kr_check_signature(const knot_rdata_t *rrsig, + const dnssec_key_t *key, const knot_rrset_t *covered, + int trim_labels) +{ + if (!rrsig || !key || !dnssec_key_can_verify(key)) + return kr_error(EINVAL); + + int ret = 0; + dnssec_sign_ctx_t *sign_ctx = NULL; + dnssec_binary_t signature = { + .data = /*const-cast*/(uint8_t*)knot_rrsig_signature(rrsig), + .size = knot_rrsig_signature_len(rrsig), + }; + if (!signature.data || !signature.size) { + ret = kr_error(EINVAL); + goto fail; + } + + if (dnssec_sign_new(&sign_ctx, key) != 0) { + ret = kr_error(ENOMEM); + goto fail; + } + + uint32_t orig_ttl = knot_rrsig_original_ttl(rrsig); + + if (sign_ctx_add_data(sign_ctx, rrsig->data, covered, orig_ttl, trim_labels) != 0) { + ret = kr_error(ENOMEM); + goto fail; + } + + ret = dnssec_sign_verify(sign_ctx, false, &signature); + if (ret != 0) { + ret = kr_error(EBADMSG); + goto fail; + } + + ret = kr_ok(); + +fail: + dnssec_sign_free(sign_ctx); + return ret; +} diff --git a/lib/dnssec/signature.h b/lib/dnssec/signature.h new file mode 100644 index 0000000..1cc6c8f --- /dev/null +++ b/lib/dnssec/signature.h @@ -0,0 +1,29 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#pragma once + +#include <libdnssec/key.h> +#include <libknot/rrset.h> + +/** + * Performs referral authentication according to RFC4035 5.2, bullet 2 + * @param ref Referral RRSet. Currently only DS can be used. + * @param key Already parsed key. + * @return 0 or error code. In particular: DNSSEC_INVALID_DS_ALGORITHM + * in case *all* DSs in ref use an unimplemented algorithm. + */ +int kr_authenticate_referral(const knot_rrset_t *ref, const dnssec_key_t *key); + +/** + * Check the signature of the supplied RRSet. + * @param rrsig A single signature. + * @param key Key to be used to validate the signature. + * @param covered The covered RRSet. + * @param trim_labels Number of the leftmost labels to be removed and replaced with '*.'. + * @return 0 if signature valid, error code else. + */ +int kr_check_signature(const knot_rdata_t *rrsig, + const dnssec_key_t *key, const knot_rrset_t *covered, + int trim_labels); diff --git a/lib/dnssec/ta.c b/lib/dnssec/ta.c new file mode 100644 index 0000000..becf7d8 --- /dev/null +++ b/lib/dnssec/ta.c @@ -0,0 +1,154 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#include <contrib/cleanup.h> +#include <libknot/descriptor.h> +#include <libknot/rdataset.h> +#include <libknot/rrset.h> +#include <libknot/packet/wire.h> +#include <libdnssec/key.h> +#include <libdnssec/error.h> + +#include "lib/defines.h" +#include "lib/dnssec.h" +#include "lib/dnssec/ta.h" +#include "lib/resolve.h" +#include "lib/utils.h" + +knot_rrset_t *kr_ta_get(trie_t *trust_anchors, const knot_dname_t *name) +{ + trie_val_t *val = trie_get_try(trust_anchors, (const char *)name, strlen((const char *)name)); + return (val) ? *val : NULL; +} + +const knot_dname_t * kr_ta_closest(const struct kr_context *ctx, const knot_dname_t *name, + const uint16_t type) +{ + kr_require(ctx && name); + if (type == KNOT_RRTYPE_DS && name[0] != '\0') { + /* DS is parent-side record, so the parent name needs to be covered. */ + name = knot_wire_next_label(name, NULL); + } + while (name) { + struct kr_context *ctx_nc = (struct kr_context *)/*const-cast*/ctx; + if (kr_ta_get(ctx_nc->trust_anchors, name)) { + return name; + } + if (kr_ta_get(ctx_nc->negative_anchors, name)) { + return NULL; + } + name = knot_wire_next_label(name, NULL); + } + return NULL; +} + +/* @internal Create DS from DNSKEY, caller MUST free dst if successful. */ +static int dnskey2ds(dnssec_binary_t *dst, const knot_dname_t *owner, const uint8_t *rdata, uint16_t rdlen) +{ + dnssec_key_t *key = NULL; + int ret = dnssec_key_new(&key); + if (ret) goto cleanup; + /* Create DS from DNSKEY and reinsert */ + const dnssec_binary_t key_data = { .size = rdlen, .data = (uint8_t *)rdata }; + ret = dnssec_key_set_rdata(key, &key_data); + if (ret) goto cleanup; + /* Accept only keys with Zone and SEP flags that aren't revoked, + * as a precaution. RFC 5011 also utilizes these flags. + * TODO: kr_dnssec_key_* names are confusing. */ + const bool flags_ok = kr_dnssec_key_zsk(rdata) && !kr_dnssec_key_revoked(rdata); + if (!flags_ok) { + auto_free char *owner_str = kr_dname_text(owner); + kr_log_error(TA, "refusing to trust %s DNSKEY because of flags %d\n", + owner_str, dnssec_key_get_flags(key)); + ret = kr_error(EILSEQ); + goto cleanup; + } else if (!kr_dnssec_key_ksk(rdata)) { + auto_free char *owner_str = kr_dname_text(owner); + int flags = dnssec_key_get_flags(key); + kr_log_warning(TA, "warning: %s DNSKEY is missing the SEP bit; " + "flags %d instead of %d\n", + owner_str, flags, flags + 1/*a little ugly*/); + } + ret = dnssec_key_set_dname(key, owner); + if (ret) goto cleanup; + ret = dnssec_key_create_ds(key, DNSSEC_KEY_DIGEST_SHA256, dst); +cleanup: + dnssec_key_free(key); + return kr_error(ret); +} + +/* @internal Insert new TA to trust anchor set, rdata MUST be of DS type. */ +static int insert_ta(trie_t *trust_anchors, const knot_dname_t *name, + uint32_t ttl, const uint8_t *rdata, uint16_t rdlen) +{ + bool is_new_key = false; + knot_rrset_t *ta_rr = kr_ta_get(trust_anchors, name); + if (!ta_rr) { + ta_rr = knot_rrset_new(name, KNOT_RRTYPE_DS, KNOT_CLASS_IN, ttl, NULL); + is_new_key = true; + } + /* Merge-in new key data */ + if (!ta_rr || (rdlen > 0 && knot_rrset_add_rdata(ta_rr, rdata, rdlen, NULL) != 0)) { + knot_rrset_free(ta_rr, NULL); + return kr_error(ENOMEM); + } + if (is_new_key) { + trie_val_t *val = trie_get_ins(trust_anchors, (const char *)name, strlen((const char *)name)); + if (kr_fails_assert(val)) + return kr_error(EINVAL); + *val = ta_rr; + } + return kr_ok(); +} + +int kr_ta_add(trie_t *trust_anchors, const knot_dname_t *name, uint16_t type, + uint32_t ttl, const uint8_t *rdata, uint16_t rdlen) +{ + if (!trust_anchors || !name) { + return kr_error(EINVAL); + } + + /* DS/DNSKEY types are accepted, for DNSKEY we + * need to compute a DS digest. */ + if (type == KNOT_RRTYPE_DS) { + return insert_ta(trust_anchors, name, ttl, rdata, rdlen); + } else if (type == KNOT_RRTYPE_DNSKEY) { + dnssec_binary_t ds_rdata = { 0, }; + int ret = dnskey2ds(&ds_rdata, name, rdata, rdlen); + if (ret != 0) { + return ret; + } + ret = insert_ta(trust_anchors, name, ttl, ds_rdata.data, ds_rdata.size); + dnssec_binary_free(&ds_rdata); + return ret; + } else { /* Invalid type for TA */ + return kr_error(EINVAL); + } +} + +/* Delete record data */ +static int del_record(trie_val_t *v, void *ext) +{ + knot_rrset_t *ta_rr = *v; + if (ta_rr) { + knot_rrset_free(ta_rr, NULL); + } + return 0; +} + +int kr_ta_del(trie_t *trust_anchors, const knot_dname_t *name) +{ + knot_rrset_t *ta_rr; + int ret = trie_del(trust_anchors, (const char *)name, strlen((const char *)name), + (trie_val_t *) &ta_rr); + if (ret == KNOT_EOK && ta_rr) + knot_rrset_free(ta_rr, NULL); + return kr_ok(); +} + +void kr_ta_clear(trie_t *trust_anchors) +{ + trie_apply(trust_anchors, del_record, NULL); + trie_clear(trust_anchors); +} diff --git a/lib/dnssec/ta.h b/lib/dnssec/ta.h new file mode 100644 index 0000000..1eb1dd9 --- /dev/null +++ b/lib/dnssec/ta.h @@ -0,0 +1,61 @@ +/* Copyright (C) CZ.NIC, z.s.p.o. <knot-resolver@labs.nic.cz> + * SPDX-License-Identifier: GPL-3.0-or-later + */ + +#pragma once + +#include "lib/defines.h" +#include "lib/generic/trie.h" +#include <libknot/rrset.h> + +/** + * Find TA RRSet by name. + * @param trust_anchors trust store + * @param name name of the TA + * @return non-empty RRSet or NULL + */ +KR_EXPORT +knot_rrset_t *kr_ta_get(trie_t *trust_anchors, const knot_dname_t *name); + +/** + * Add TA to trust store. DS or DNSKEY types are supported. + * @param trust_anchors trust store + * @param name name of the TA + * @param type RR type of the TA (DS or DNSKEY) + * @param ttl + * @param rdata + * @param rdlen + * @return 0 or an error + */ +KR_EXPORT +int kr_ta_add(trie_t *trust_anchors, const knot_dname_t *name, uint16_t type, + uint32_t ttl, const uint8_t *rdata, uint16_t rdlen); + +struct kr_context; + +/** + * Return pointer to the name of the closest positive trust anchor or NULL. + * + * "Closest" means on path towards root. Closer negative anchor results into NULL. + * @param type serves as a shorthand because DS needs to start one level higher. + */ +KR_EXPORT KR_PURE +const knot_dname_t * kr_ta_closest(const struct kr_context *ctx, const knot_dname_t *name, + const uint16_t type); + +/** + * Remove TA from trust store. + * @param trust_anchors trust store + * @param name name of the TA + * @return 0 or an error + */ +KR_EXPORT +int kr_ta_del(trie_t *trust_anchors, const knot_dname_t *name); + +/** + * Clear trust store. + * @param trust_anchors trust store + */ +KR_EXPORT +void kr_ta_clear(trie_t *trust_anchors); + |