/* $NetBSD: nsec.c,v 1.1.4.2 2024/02/29 11:38:40 martin Exp $ */ /* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * SPDX-License-Identifier: MPL-2.0 * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, you can obtain one at https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ /*! \file */ #include #include #include #include #include #include #include #include #include #include #include #include #include #define RETERR(x) \ do { \ result = (x); \ if (result != ISC_R_SUCCESS) \ goto failure; \ } while (0) void dns_nsec_setbit(unsigned char *array, unsigned int type, unsigned int bit) { unsigned int shift, mask; shift = 7 - (type % 8); mask = 1 << shift; if (bit != 0) { array[type / 8] |= mask; } else { array[type / 8] &= (~mask & 0xFF); } } bool dns_nsec_isset(const unsigned char *array, unsigned int type) { unsigned int byte, shift, mask; byte = array[type / 8]; shift = 7 - (type % 8); mask = 1 << shift; return ((byte & mask) != 0); } unsigned int dns_nsec_compressbitmap(unsigned char *map, const unsigned char *raw, unsigned int max_type) { unsigned char *start = map; unsigned int window; int octet; if (raw == NULL) { return (0); } for (window = 0; window < 256; window++) { if (window * 256 > max_type) { break; } for (octet = 31; octet >= 0; octet--) { if (*(raw + octet) != 0) { break; } } if (octet < 0) { raw += 32; continue; } *map++ = window; *map++ = octet + 1; /* * Note: potential overlapping move. */ memmove(map, raw, octet + 1); map += octet + 1; raw += 32; } return ((unsigned int)(map - start)); } isc_result_t dns_nsec_buildrdata(dns_db_t *db, dns_dbversion_t *version, dns_dbnode_t *node, const dns_name_t *target, unsigned char *buffer, dns_rdata_t *rdata) { isc_result_t result; dns_rdataset_t rdataset; isc_region_t r; unsigned int i; unsigned char *nsec_bits, *bm; unsigned int max_type; dns_rdatasetiter_t *rdsiter; REQUIRE(target != NULL); memset(buffer, 0, DNS_NSEC_BUFFERSIZE); dns_name_toregion(target, &r); memmove(buffer, r.base, r.length); r.base = buffer; /* * Use the end of the space for a raw bitmap leaving enough * space for the window identifiers and length octets. */ bm = r.base + r.length + 512; nsec_bits = r.base + r.length; dns_nsec_setbit(bm, dns_rdatatype_rrsig, 1); dns_nsec_setbit(bm, dns_rdatatype_nsec, 1); max_type = dns_rdatatype_nsec; dns_rdataset_init(&rdataset); rdsiter = NULL; result = dns_db_allrdatasets(db, node, version, 0, 0, &rdsiter); if (result != ISC_R_SUCCESS) { return (result); } for (result = dns_rdatasetiter_first(rdsiter); result == ISC_R_SUCCESS; result = dns_rdatasetiter_next(rdsiter)) { dns_rdatasetiter_current(rdsiter, &rdataset); if (rdataset.type != dns_rdatatype_nsec && rdataset.type != dns_rdatatype_nsec3 && rdataset.type != dns_rdatatype_rrsig) { if (rdataset.type > max_type) { max_type = rdataset.type; } dns_nsec_setbit(bm, rdataset.type, 1); } dns_rdataset_disassociate(&rdataset); } /* * At zone cuts, deny the existence of glue in the parent zone. */ if (dns_nsec_isset(bm, dns_rdatatype_ns) && !dns_nsec_isset(bm, dns_rdatatype_soa)) { for (i = 0; i <= max_type; i++) { if (dns_nsec_isset(bm, i) && !dns_rdatatype_iszonecutauth((dns_rdatatype_t)i)) { dns_nsec_setbit(bm, i, 0); } } } dns_rdatasetiter_destroy(&rdsiter); if (result != ISC_R_NOMORE) { return (result); } nsec_bits += dns_nsec_compressbitmap(nsec_bits, bm, max_type); r.length = (unsigned int)(nsec_bits - r.base); INSIST(r.length <= DNS_NSEC_BUFFERSIZE); dns_rdata_fromregion(rdata, dns_db_class(db), dns_rdatatype_nsec, &r); return (ISC_R_SUCCESS); } isc_result_t dns_nsec_build(dns_db_t *db, dns_dbversion_t *version, dns_dbnode_t *node, const dns_name_t *target, dns_ttl_t ttl) { isc_result_t result; dns_rdata_t rdata = DNS_RDATA_INIT; unsigned char data[DNS_NSEC_BUFFERSIZE]; dns_rdatalist_t rdatalist; dns_rdataset_t rdataset; dns_rdataset_init(&rdataset); dns_rdata_init(&rdata); RETERR(dns_nsec_buildrdata(db, version, node, target, data, &rdata)); dns_rdatalist_init(&rdatalist); rdatalist.rdclass = dns_db_class(db); rdatalist.type = dns_rdatatype_nsec; rdatalist.ttl = ttl; ISC_LIST_APPEND(rdatalist.rdata, &rdata, link); RETERR(dns_rdatalist_tordataset(&rdatalist, &rdataset)); result = dns_db_addrdataset(db, node, version, 0, &rdataset, 0, NULL); if (result == DNS_R_UNCHANGED) { result = ISC_R_SUCCESS; } failure: if (dns_rdataset_isassociated(&rdataset)) { dns_rdataset_disassociate(&rdataset); } return (result); } bool dns_nsec_typepresent(dns_rdata_t *nsec, dns_rdatatype_t type) { dns_rdata_nsec_t nsecstruct; isc_result_t result; bool present; unsigned int i, len, window; REQUIRE(nsec != NULL); REQUIRE(nsec->type == dns_rdatatype_nsec); /* This should never fail */ result = dns_rdata_tostruct(nsec, &nsecstruct, NULL); INSIST(result == ISC_R_SUCCESS); present = false; for (i = 0; i < nsecstruct.len; i += len) { INSIST(i + 2 <= nsecstruct.len); window = nsecstruct.typebits[i]; len = nsecstruct.typebits[i + 1]; INSIST(len > 0 && len <= 32); i += 2; INSIST(i + len <= nsecstruct.len); if (window * 256 > type) { break; } if ((window + 1) * 256 <= type) { continue; } if (type < (window * 256) + len * 8) { present = dns_nsec_isset(&nsecstruct.typebits[i], type % 256); } break; } dns_rdata_freestruct(&nsecstruct); return (present); } isc_result_t dns_nsec_nseconly(dns_db_t *db, dns_dbversion_t *version, bool *answer) { dns_dbnode_t *node = NULL; dns_rdataset_t rdataset; dns_rdata_dnskey_t dnskey; isc_result_t result; REQUIRE(answer != NULL); dns_rdataset_init(&rdataset); result = dns_db_getoriginnode(db, &node); if (result != ISC_R_SUCCESS) { return (result); } result = dns_db_findrdataset(db, node, version, dns_rdatatype_dnskey, 0, 0, &rdataset, NULL); dns_db_detachnode(db, &node); if (result == ISC_R_NOTFOUND) { *answer = false; } if (result != ISC_R_SUCCESS) { return (result); } for (result = dns_rdataset_first(&rdataset); result == ISC_R_SUCCESS; result = dns_rdataset_next(&rdataset)) { dns_rdata_t rdata = DNS_RDATA_INIT; dns_rdataset_current(&rdataset, &rdata); result = dns_rdata_tostruct(&rdata, &dnskey, NULL); RUNTIME_CHECK(result == ISC_R_SUCCESS); if (dnskey.algorithm == DST_ALG_RSAMD5 || dnskey.algorithm == DST_ALG_RSASHA1) { break; } } dns_rdataset_disassociate(&rdataset); if (result == ISC_R_SUCCESS) { *answer = true; } if (result == ISC_R_NOMORE) { *answer = false; result = ISC_R_SUCCESS; } return (result); } /*% * Return ISC_R_SUCCESS if we can determine that the name doesn't exist * or we can determine whether there is data or not at the name. * If the name does not exist return the wildcard name. * * Return ISC_R_IGNORE when the NSEC is not the appropriate one. */ isc_result_t dns_nsec_noexistnodata(dns_rdatatype_t type, const dns_name_t *name, const dns_name_t *nsecname, dns_rdataset_t *nsecset, bool *exists, bool *data, dns_name_t *wild, dns_nseclog_t logit, void *arg) { int order; dns_rdata_t rdata = DNS_RDATA_INIT; isc_result_t result; dns_namereln_t relation; unsigned int olabels, nlabels, labels; dns_rdata_nsec_t nsec; bool atparent; bool ns; bool soa; REQUIRE(exists != NULL); REQUIRE(data != NULL); REQUIRE(nsecset != NULL && nsecset->type == dns_rdatatype_nsec); result = dns_rdataset_first(nsecset); if (result != ISC_R_SUCCESS) { (*logit)(arg, ISC_LOG_DEBUG(3), "failure processing NSEC set"); return (result); } dns_rdataset_current(nsecset, &rdata); (*logit)(arg, ISC_LOG_DEBUG(3), "looking for relevant NSEC"); relation = dns_name_fullcompare(name, nsecname, &order, &olabels); if (order < 0) { /* * The name is not within the NSEC range. */ (*logit)(arg, ISC_LOG_DEBUG(3), "NSEC does not cover name, before NSEC"); return (ISC_R_IGNORE); } if (order == 0) { /* * The names are the same. If we are validating "." * then atparent should not be set as there is no parent. */ atparent = (olabels != 1) && dns_rdatatype_atparent(type); ns = dns_nsec_typepresent(&rdata, dns_rdatatype_ns); soa = dns_nsec_typepresent(&rdata, dns_rdatatype_soa); if (ns && !soa) { if (!atparent) { /* * This NSEC record is from somewhere higher in * the DNS, and at the parent of a delegation. * It can not be legitimately used here. */ (*logit)(arg, ISC_LOG_DEBUG(3), "ignoring parent nsec"); return (ISC_R_IGNORE); } } else if (atparent && ns && soa) { /* * This NSEC record is from the child. * It can not be legitimately used here. */ (*logit)(arg, ISC_LOG_DEBUG(3), "ignoring child nsec"); return (ISC_R_IGNORE); } if (type == dns_rdatatype_cname || type == dns_rdatatype_nxt || type == dns_rdatatype_nsec || type == dns_rdatatype_key || !dns_nsec_typepresent(&rdata, dns_rdatatype_cname)) { *exists = true; *data = dns_nsec_typepresent(&rdata, type); (*logit)(arg, ISC_LOG_DEBUG(3), "nsec proves name exists (owner) data=%d", *data); return (ISC_R_SUCCESS); } (*logit)(arg, ISC_LOG_DEBUG(3), "NSEC proves CNAME exists"); return (ISC_R_IGNORE); } if (relation == dns_namereln_subdomain && dns_nsec_typepresent(&rdata, dns_rdatatype_ns) && !dns_nsec_typepresent(&rdata, dns_rdatatype_soa)) { /* * This NSEC record is from somewhere higher in * the DNS, and at the parent of a delegation or * at a DNAME. * It can not be legitimately used here. */ (*logit)(arg, ISC_LOG_DEBUG(3), "ignoring parent nsec"); return (ISC_R_IGNORE); } if (relation == dns_namereln_subdomain && dns_nsec_typepresent(&rdata, dns_rdatatype_dname)) { (*logit)(arg, ISC_LOG_DEBUG(3), "nsec proves covered by dname"); *exists = false; return (DNS_R_DNAME); } result = dns_rdata_tostruct(&rdata, &nsec, NULL); if (result != ISC_R_SUCCESS) { return (result); } relation = dns_name_fullcompare(&nsec.next, name, &order, &nlabels); if (order == 0) { dns_rdata_freestruct(&nsec); (*logit)(arg, ISC_LOG_DEBUG(3), "ignoring nsec matches next name"); return (ISC_R_IGNORE); } if (order < 0 && !dns_name_issubdomain(nsecname, &nsec.next)) { /* * The name is not within the NSEC range. */ dns_rdata_freestruct(&nsec); (*logit)(arg, ISC_LOG_DEBUG(3), "ignoring nsec because name is past end of range"); return (ISC_R_IGNORE); } if (order > 0 && relation == dns_namereln_subdomain) { (*logit)(arg, ISC_LOG_DEBUG(3), "nsec proves name exist (empty)"); dns_rdata_freestruct(&nsec); *exists = true; *data = false; return (ISC_R_SUCCESS); } if (wild != NULL) { dns_name_t common; dns_name_init(&common, NULL); if (olabels > nlabels) { labels = dns_name_countlabels(nsecname); dns_name_getlabelsequence(nsecname, labels - olabels, olabels, &common); } else { labels = dns_name_countlabels(&nsec.next); dns_name_getlabelsequence(&nsec.next, labels - nlabels, nlabels, &common); } result = dns_name_concatenate(dns_wildcardname, &common, wild, NULL); if (result != ISC_R_SUCCESS) { dns_rdata_freestruct(&nsec); (*logit)(arg, ISC_LOG_DEBUG(3), "failure generating wildcard name"); return (result); } } dns_rdata_freestruct(&nsec); (*logit)(arg, ISC_LOG_DEBUG(3), "nsec range ok"); *exists = false; return (ISC_R_SUCCESS); }