From bef141d5795429cab745f29f7d080d1e2ea8f164 Mon Sep 17 00:00:00 2001
From: Petr Mensik <pemensik@redhat.com>
Date: Mon, 12 Feb 2024 20:33:41 +0100
Subject: [PATCH] Prevent assertion failure when nxdomain-redirect is used with
 RFC 1918 reverse zones

6316.	[security]	Specific queries could trigger an assertion check with
			nxdomain-redirect enabled. (CVE-2023-5517) [GL #4281]
---
 lib/ns/query.c | 25 ++++++++++++-------------
 1 file changed, 12 insertions(+), 13 deletions(-)

diff --git a/lib/ns/query.c b/lib/ns/query.c
index 4fe3e30..cc1d179 100644
--- a/lib/ns/query.c
+++ b/lib/ns/query.c
@@ -453,10 +453,10 @@ static void
 query_addnxrrsetnsec(query_ctx_t *qctx);
 
 static isc_result_t
-query_nxdomain(query_ctx_t *qctx, bool empty_wild);
+query_nxdomain(query_ctx_t *qctx, isc_result_t result);
 
 static isc_result_t
-query_redirect(query_ctx_t *qctx);
+query_redirect(query_ctx_t *qctx, isc_result_t result);
 
 static isc_result_t
 query_ncache(query_ctx_t *qctx, isc_result_t result);
@@ -7262,8 +7262,7 @@ query_usestale(query_ctx_t *qctx, isc_result_t result) {
  * result from the search.
  */
 static isc_result_t
-query_gotanswer(query_ctx_t *qctx, isc_result_t res) {
-	isc_result_t result = res;
+query_gotanswer(query_ctx_t *qctx, isc_result_t result) {
 	char errmsg[256];
 
 	CCTRACE(ISC_LOG_DEBUG(3), "query_gotanswer");
@@ -7333,16 +7332,16 @@ root_key_sentinel:
 		return (query_nodata(qctx, DNS_R_NXRRSET));
 
 	case DNS_R_EMPTYWILD:
-		return (query_nxdomain(qctx, true));
+		return (query_nxdomain(qctx, DNS_R_EMPTYWILD));
 
 	case DNS_R_NXDOMAIN:
-		return (query_nxdomain(qctx, false));
+		return (query_nxdomain(qctx, DNS_R_NXDOMAIN));
 
 	case DNS_R_COVERINGNSEC:
 		return (query_coveringnsec(qctx));
 
 	case DNS_R_NCACHENXDOMAIN:
-		result = query_redirect(qctx);
+		result = query_redirect(qctx, result);
 		if (result != ISC_R_COMPLETE) {
 			return (result);
 		}
@@ -9155,10 +9154,10 @@ query_addnxrrsetnsec(query_ctx_t *qctx) {
  * Handle NXDOMAIN and empty wildcard responses.
  */
 static isc_result_t
-query_nxdomain(query_ctx_t *qctx, bool empty_wild) {
+query_nxdomain(query_ctx_t *qctx, isc_result_t result) {
 	dns_section_t section;
 	uint32_t ttl;
-	isc_result_t result;
+	bool empty_wild = (result == DNS_R_EMPTYWILD);
 
 	CCTRACE(ISC_LOG_DEBUG(3), "query_nxdomain");
 
@@ -9167,7 +9166,7 @@ query_nxdomain(query_ctx_t *qctx, bool empty_wild) {
 	INSIST(qctx->is_zone || REDIRECT(qctx->client));
 
 	if (!empty_wild) {
-		result = query_redirect(qctx);
+		result = query_redirect(qctx, result);
 		if (result != ISC_R_COMPLETE) {
 			return (result);
 		}
@@ -9253,7 +9252,7 @@ cleanup:
  * redirecting, so query processing should continue past it.
  */
 static isc_result_t
-query_redirect(query_ctx_t *qctx) {
+query_redirect(query_ctx_t *qctx, isc_result_t saved_result) {
 	isc_result_t result;
 
 	CCTRACE(ISC_LOG_DEBUG(3), "query_redirect");
@@ -9294,7 +9293,7 @@ query_redirect(query_ctx_t *qctx) {
 		SAVE(qctx->client->query.redirect.rdataset, qctx->rdataset);
 		SAVE(qctx->client->query.redirect.sigrdataset,
 		     qctx->sigrdataset);
-		qctx->client->query.redirect.result = DNS_R_NCACHENXDOMAIN;
+		qctx->client->query.redirect.result = saved_result;
 		dns_name_copynf(qctx->fname,
 				qctx->client->query.redirect.fname);
 		qctx->client->query.redirect.authoritative =
@@ -9908,7 +9907,7 @@ query_coveringnsec(query_ctx_t *qctx) {
 	 * We now have the proof that we have an NXDOMAIN.  Apply
 	 * NXDOMAIN redirection if configured.
 	 */
-	result = query_redirect(qctx);
+	result = query_redirect(qctx, DNS_R_COVERINGNSEC);
 	if (result != ISC_R_COMPLETE) {
 		redirected = true;
 		goto cleanup;
-- 
2.43.0