Add additional name checks when using a forwarder

When using a forwarder, check that the owner name of response
records are within the bailiwick of the forwarded name space.

diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index dd82f273a4d5a2d34edd1cbcba8c9daf78a71b34..2f67aba873d37e6b1e25737d241be53c9609710f 100644 (file)
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -339,6 +339,8 @@ struct fetchctx {
        dns_fetch_t *qminfetch;
        dns_rdataset_t qminrrset;
        dns_name_t qmindcname;
+       dns_fixedname_t fwdfname;
+       dns_name_t *fwdname;
 
        /*%
         * The number of events we're waiting for.
@@ -3766,6 +3768,7 @@ fctx_getaddresses(fetchctx_t *fctx, bool badcache) {
                if (result == ISC_R_SUCCESS) {
                        fwd = ISC_LIST_HEAD(forwarders->fwdrs);
                        fctx->fwdpolicy = forwarders->fwdpolicy;
+                       dns_name_copynf(domain, fctx->fwdname);
                        if (fctx->fwdpolicy == dns_fwdpolicy_only &&
                            isstrictsubdomain(domain, &fctx->domain))
                        {
@@ -5155,6 +5158,9 @@ fctx_create(dns_resolver_t *res, const dns_name_t *name, dns_rdatatype_t type,
        fctx->restarts = 0;
        fctx->querysent = 0;
        fctx->referrals = 0;
+
+       fctx->fwdname = dns_fixedname_initname(&fctx->fwdfname);
+
        TIME_NOW(&fctx->start);
        fctx->timeouts = 0;
        fctx->lamecount = 0;
@@ -5217,6 +5223,7 @@ fctx_create(dns_resolver_t *res, const dns_name_t *name, dns_rdatatype_t type,
                                           fname, &forwarders);
                if (result == ISC_R_SUCCESS) {
                        fctx->fwdpolicy = forwarders->fwdpolicy;
+                       dns_name_copynf(fname, fctx->fwdname);
                }
 
                if (fctx->fwdpolicy != dns_fwdpolicy_only) {
@@ -7120,6 +7127,15 @@ mark_related(dns_name_t *name, dns_rdataset_t *rdataset, bool external,
        }
 }
 
+static inline bool
+name_external(const dns_name_t *name, fetchctx_t *fctx) {
+       if (ISFORWARDER(fctx->addrinfo)) {
+               return (!dns_name_issubdomain(name, fctx->fwdname));
+       }
+
+       return (!dns_name_issubdomain(name, &fctx->domain));
+}
+
 static isc_result_t
 check_section(void *arg, const dns_name_t *addname, dns_rdatatype_t type,
              dns_section_t section) {
@@ -7146,7 +7162,7 @@ check_section(void *arg, const dns_name_t *addname, dns_rdatatype_t type,
        result = dns_message_findname(rctx->query->rmessage, section, addname,
                                      dns_rdatatype_any, 0, &name, NULL);
        if (result == ISC_R_SUCCESS) {
-               external = !dns_name_issubdomain(name, &fctx->domain);
+               external = name_external(name, fctx);
                if (type == dns_rdatatype_a) {
                        for (rdataset = ISC_LIST_HEAD(name->list);
                             rdataset != NULL;
@@ -8770,6 +8786,13 @@ rctx_answer_scan(respctx_t *rctx) {
                        break;
 
                case dns_namereln_subdomain:
+                       /*
+                        * Don't accept DNAME from parent namespace.
+                        */
+                       if (name_external(name, fctx)) {
+                               continue;
+                       }
+
                        /*
                         * In-scope DNAME records must have at least
                         * as many labels as the domain being queried.
@@ -9083,13 +9106,11 @@ rctx_authority_positive(respctx_t *rctx) {
                                       DNS_SECTION_AUTHORITY);
        while (!done && result == ISC_R_SUCCESS) {
                dns_name_t *name = NULL;
-               bool external;
 
                dns_message_currentname(rctx->query->rmessage,
                                        DNS_SECTION_AUTHORITY, &name);
-               external = !dns_name_issubdomain(name, &fctx->domain);
 
-               if (!external) {
+               if (!name_external(name, fctx)) {
                        dns_rdataset_t *rdataset = NULL;
 
                        /*
@@ -9476,7 +9497,10 @@ rctx_authority_dnssec(respctx_t *rctx) {
                }
 
                if (!dns_name_issubdomain(name, &fctx->domain)) {
-                       /* Invalid name found; preserve it for logging later */
+                       /*
+                        * Invalid name found; preserve it for logging
+                        * later.
+                        */
                        rctx->found_name = name;
                        rctx->found_type = ISC_LIST_HEAD(name->list)->type;
                        continue;