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-rw-r--r--lib/dns/nsec.c466
1 files changed, 466 insertions, 0 deletions
diff --git a/lib/dns/nsec.c b/lib/dns/nsec.c
new file mode 100644
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--- /dev/null
+++ b/lib/dns/nsec.c
@@ -0,0 +1,466 @@
+/*
+ * 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 <stdbool.h>
+
+#include <isc/log.h>
+#include <isc/string.h>
+#include <isc/util.h>
+
+#include <dns/db.h>
+#include <dns/nsec.h>
+#include <dns/rdata.h>
+#include <dns/rdatalist.h>
+#include <dns/rdataset.h>
+#include <dns/rdatasetiter.h>
+#include <dns/rdatastruct.h>
+#include <dns/result.h>
+
+#include <dst/dst.h>
+
+#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);
+}
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