From 03ecba2cdc8d9a6cb6bdf863ffa1e230cb4ff223 Mon Sep 17 00:00:00 2001
From: Evan Hunt <each@isc.org>
Date: Mon, 4 Jun 2018 15:57:58 -0700
Subject: [PATCH] allow-recursion could incorrectly inherit from the default
 allow-query

---
 CHANGES            |  7 ++++++-
 bin/named/server.c | 43 ++++++++++++++++++++++++++++++++-----------
 doc/arm/notes.xml  |  8 ++++++--
 3 files changed, 44 insertions(+), 14 deletions(-)

diff --git a/CHANGES b/CHANGES
index c09900074d..a6c65eca9f 100644
--- a/CHANGES
+++ b/CHANGES
@@ -29,7 +29,12 @@
 4961.	[protocol]	Remove support for ECC-GOST (GOST R 34.11-94).
 			[GL #295]
 
-4960.	[placeholder]
+4960.	[security]	When recursion is enabled, but the "allow-recursion"
+			and "allow-query-cache" ACLs are not specified,
+			they should be limited to local networks,
+			but were inadvertently set to match the default
+			"allow-query", thus allowing remote queries.
+			(CVE-2018-5738) [GL #309]
 
 4959.	[func]		NSID logging (enabled by the "request-nsid" option)
 			now has its own "nsid" category, instead of using the
diff --git a/bin/named/server.c b/bin/named/server.c
index c8ff38e4c9..8644581df9 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -3726,10 +3726,6 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 	CHECKM(named_config_getport(config, &port), "port");
 	dns_view_setdstport(view, port);
 
-	CHECK(configure_view_acl(vconfig, config, named_g_config,
-				 "allow-query", NULL, actx,
-				 named_g_mctx, &view->queryacl));
-
 	/*
 	 * Make the list of response policy zone names for a view that
 	 * is used for real lookups and so cares about hints.
@@ -4714,21 +4710,35 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 				 "allow-query-cache-on", NULL, actx,
 				 named_g_mctx, &view->cacheonacl));
 	/*
-	 * Set "allow-query-cache", "allow-recursion", and
-	 * "allow-recursion-on" acls if configured in named.conf.
-	 * (Ignore the global defaults for now, because these ACLs
-	 * can inherit from each other when only some of them set at
-	 * the options/view level.)
+	 * Set the "allow-query", "allow-query-cache", "allow-recursion",
+	 * and "allow-recursion-on" ACLs if configured in named.conf, but
+	 * NOT from the global defaults. This is done by leaving the third
+	 * argument to configure_view_acl() NULL.
+	 *
+	 * We ignore the global defaults here because these ACLs
+	 * can inherit from each other.  If any are still unset after
+	 * applying the inheritance rules, we'll look up the defaults at
+	 * that time.
 	 */
-	CHECK(configure_view_acl(vconfig, config, NULL, "allow-query-cache",
-				 NULL, actx, named_g_mctx, &view->cacheacl));
+
+	/* named.conf only */
+	CHECK(configure_view_acl(vconfig, config, NULL,
+				 "allow-query", NULL, actx,
+				 named_g_mctx, &view->queryacl));
+
+	/* named.conf only */
+	CHECK(configure_view_acl(vconfig, config, NULL,
+				 "allow-query-cache", NULL, actx,
+				 named_g_mctx, &view->cacheacl));
 
 	if (strcmp(view->name, "_bind") != 0 &&
 	    view->rdclass != dns_rdataclass_chaos)
 	{
+		/* named.conf only */
 		CHECK(configure_view_acl(vconfig, config, NULL,
 					 "allow-recursion", NULL, actx,
 					 named_g_mctx, &view->recursionacl));
+		/* named.conf only */
 		CHECK(configure_view_acl(vconfig, config, NULL,
 					 "allow-recursion-on", NULL, actx,
 					 named_g_mctx, &view->recursiononacl));
@@ -4766,18 +4776,21 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 		 * the global config.
 		 */
 		if (view->recursionacl == NULL) {
+			/* global default only */
 			CHECK(configure_view_acl(NULL, NULL, named_g_config,
 						 "allow-recursion", NULL,
 						 actx, named_g_mctx,
 						 &view->recursionacl));
 		}
 		if (view->recursiononacl == NULL) {
+			/* global default only */
 			CHECK(configure_view_acl(NULL, NULL, named_g_config,
 						 "allow-recursion-on", NULL,
 						 actx, named_g_mctx,
 						 &view->recursiononacl));
 		}
 		if (view->cacheacl == NULL) {
+			/* global default only */
 			CHECK(configure_view_acl(NULL, NULL, named_g_config,
 						 "allow-query-cache", NULL,
 						 actx, named_g_mctx,
@@ -4791,6 +4804,14 @@ configure_view(dns_view_t *view, dns_viewlist_t *viewlist,
 		CHECK(dns_acl_none(mctx, &view->cacheacl));
 	}
 
+	if (view->queryacl == NULL) {
+		/* global default only */
+		CHECK(configure_view_acl(NULL, NULL, named_g_config,
+					 "allow-query", NULL,
+					 actx, named_g_mctx,
+					 &view->queryacl));
+	}
+
 	/*
 	 * Ignore case when compressing responses to the specified
 	 * clients. This causes case not always to be preserved,
diff --git a/doc/arm/notes.xml b/doc/arm/notes.xml
index abc681dd28..627a3f9f50 100644
--- a/doc/arm/notes.xml
+++ b/doc/arm/notes.xml
@@ -65,7 +65,11 @@
     <itemizedlist>
       <listitem>
 	<para>
-	  None.
+	  When recursion is enabled but the <command>allow-recursion</command>
+	  and <command>allow-query-cache</command> ACLs are not specified, they
+	  should be limited to local networks, but they were inadvertently set
+	  to match the default <command>allow-query</command>, thus allowing
+	  remote queries. This flaw is disclosed in CVE-2018-5738. [GL #309]
 	</para>
       </listitem>
     </itemizedlist>
@@ -89,7 +93,7 @@
 	  information about root key rollover status can be gathered.
 	  To disable this feature, add
 	  <command>root-key-sentinel no;</command> to
-	  <filename>named.conf</filename>.
+	  <filename>named.conf</filename>. [GL #37]
 	</para>
       </listitem>
       <listitem>