Process DNS rebinding protection after DNSSEC

internal/dnsforward/config.go

@@ -78,7 +78,7 @@ type FilteringConfig struct {
 
 	// DNS rebinding protection settings
 	// --
-	RebindingEnabled      bool     `yaml:"rebinding_enabled"`
+	RebindingProtectionEnabled bool     `yaml:"rebinding_protection_enabled"`
 	RebindingAllowedHosts      []string `yaml:"rebinding_allowed_hosts"`
 
 	// Other settings

internal/dnsforward/dns.go

@@ -48,6 +48,7 @@ func (s *Server) handleDNSRequest(_ *proxy.Proxy, d *proxy.DNSContext) error {
 		processFilteringBeforeRequest,
 		processUpstream,
 		processDNSSECAfterResponse,
+		processRebindingFilteringAfterResponse,
 		processFilteringAfterResponse,
 		s.ipset.process,
 		processQueryLogsAndStats,

internal/dnsforward/dnsforward_test.go

@@ -738,6 +738,91 @@ func TestRewrite(t *testing.T) {
 	_ = s.Stop()
 }
 
+func TestBlockedDNSRebinding(t *testing.T) {
+	s := createTestServer(t)
+
+	err := s.Start()
+	if err != nil {
+		t.Fatalf("Failed to start server: %s", err)
+	}
+	addr := s.dnsProxy.Addr(proxy.ProtoUDP)
+
+	//
+	// DNS rebinding protection
+	//
+	req := dns.Msg{}
+	req.Id = dns.Id()
+	req.RecursionDesired = true
+	req.Question = []dns.Question{
+		{Name: "192-168-1-250.nip.io.", Qtype: dns.TypeA, Qclass: dns.ClassINET},
+	}
+
+	s.conf.RebindingProtectionEnabled = true
+	reply, err := dns.Exchange(&req, addr.String())
+	if err != nil {
+		t.Fatalf("Couldn't talk to server %s: %s", addr, err)
+	}
+
+	if len(reply.Answer) != 1 {
+		t.Fatalf("DNS server %s returned reply with wrong number of answers - %d", addr, len(reply.Answer))
+	}
+
+	a, ok := reply.Answer[0].(*dns.A)
+	if !ok {
+		t.Fatalf("DNS server %s returned wrong answer type instead of A: %v", addr, reply.Answer[0])
+	}
+
+	if !net.IPv4zero.Equal(a.A) {
+		t.Fatalf("DNS server %s returned wrong answer instead of 0.0.0.0: %v", addr, a.A)
+	}
+
+	s.conf.RebindingProtectionEnabled = false
+	reply, err = dns.Exchange(&req, addr.String())
+	if err != nil {
+		t.Fatalf("Couldn't talk to server %s: %s", addr, err)
+	}
+
+	if len(reply.Answer) != 1 {
+		t.Fatalf("DNS server %s returned reply with wrong number of answers - %d", addr, len(reply.Answer))
+	}
+
+	a, ok = reply.Answer[0].(*dns.A)
+	if !ok {
+		t.Fatalf("DNS server %s returned wrong answer type instead of A: %v", addr, reply.Answer[0])
+	}
+
+	if !net.IPv4(192, 168, 1, 250).Equal(a.A) {
+		t.Fatalf("DNS server %s returned wrong answer instead of 192.168.1.250: %v", addr, a.A)
+	}
+
+	s.conf.RebindingProtectionEnabled = true
+	s.conf.RebindingAllowedHosts = []string{
+		"nip.io.",
+	}
+	reply, err = dns.Exchange(&req, addr.String())
+	if err != nil {
+		t.Fatalf("Couldn't talk to server %s: %s", addr, err)
+	}
+
+	if len(reply.Answer) != 1 {
+		t.Fatalf("DNS server %s returned reply with wrong number of answers - %d", addr, len(reply.Answer))
+	}
+
+	a, ok = reply.Answer[0].(*dns.A)
+	if !ok {
+		t.Fatalf("DNS server %s returned wrong answer type instead of A: %v", addr, reply.Answer[0])
+	}
+
+	if !net.IPv4(192, 168, 1, 250).Equal(a.A) {
+		t.Fatalf("DNS server %s returned wrong answer instead of 192.168.1.250: %v", addr, a.A)
+	}
+
+	err = s.Stop()
+	if err != nil {
+		t.Fatalf("DNS server failed to stop: %s", err)
+	}
+}
+
 func createTestServer(t *testing.T) *Server {
 	rules := `||nxdomain.example.org
 ||null.example.org^

internal/dnsforward/http.go

@@ -37,6 +37,9 @@ type dnsConfig struct {
 	CacheSize         *uint32 `json:"cache_size"`
 	CacheMinTTL       *uint32 `json:"cache_ttl_min"`
 	CacheMaxTTL       *uint32 `json:"cache_ttl_max"`
+
+	RebindingProtectionEnabled *bool     `json:"rebinding_protection_enabled"`
+	RebindingAllowedHosts      *[]string `json:"rebinding_allowed_hosts"`
 }
 
 func (s *Server) getDNSConfig() dnsConfig {
@@ -61,6 +64,8 @@ func (s *Server) getDNSConfig() dnsConfig {
 	} else if s.conf.AllServers {
 		upstreamMode = "parallel"
 	}
+	rebindingEnabled := s.conf.RebindingProtectionEnabled
+	rebindingAllowedHosts := stringArrayDup(s.conf.RebindingAllowedHosts)
 	s.RUnlock()
 	return dnsConfig{
 		Upstreams:                  &upstreams,
@@ -78,6 +83,8 @@ func (s *Server) getDNSConfig() dnsConfig {
 		CacheMinTTL:                &CacheMinTTL,
 		CacheMaxTTL:                &CacheMaxTTL,
 		UpstreamMode:               &upstreamMode,
+		RebindingProtectionEnabled: &rebindingEnabled,
+		RebindingAllowedHosts:      &rebindingAllowedHosts,
 	}
 }
 
@@ -301,6 +308,14 @@ func (s *Server) setConfig(dc dnsConfig) (restart bool) {
 			s.conf.FastestAddr = false
 		}
 	}
+
+	if dc.RebindingProtectionEnabled != nil {
+		s.conf.RebindingProtectionEnabled = *dc.RebindingProtectionEnabled
+	}
+
+	if dc.RebindingAllowedHosts != nil {
+		s.conf.RebindingAllowedHosts = *dc.RebindingAllowedHosts
+	}
 	s.Unlock()
 	s.conf.ConfigModified()
 	return restart

internal/dnsforward/http_test.go

@@ -29,7 +29,7 @@ func TestDNSForwardHTTTP_handleGetConfig(t *testing.T) {
 		conf: func() ServerConfig {
 			return defaultConf
 		},
-		want: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		want: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name: "fastest_addr",
 		conf: func() ServerConfig {
@@ -37,7 +37,7 @@ func TestDNSForwardHTTTP_handleGetConfig(t *testing.T) {
 			conf.FastestAddr = true
 			return conf
 		},
-		want: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"fastest_addr\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		want: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"fastest_addr\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name: "parallel",
 		conf: func() ServerConfig {
@@ -45,7 +45,7 @@ func TestDNSForwardHTTTP_handleGetConfig(t *testing.T) {
 			conf.AllServers = true
 			return conf
 		},
-		want: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"parallel\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		want: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"parallel\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}}
 
 	for _, tc := range testCases {
@@ -73,7 +73,7 @@ func TestDNSForwardHTTTP_handleSetConfig(t *testing.T) {
 
 	w := httptest.NewRecorder()
 
-	const defaultConfJSON = "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n"
+	const defaultConfJSON = "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n"
 	testCases := []struct {
 		name    string
 		req     string
@@ -83,52 +83,52 @@ func TestDNSForwardHTTTP_handleSetConfig(t *testing.T) {
 		name:    "upstream_dns",
 		req:     "{\"upstream_dns\":[\"8.8.8.8:77\",\"8.8.4.4:77\"]}",
 		wantSet: "",
-		wantGet: "{\"upstream_dns\":[\"8.8.8.8:77\",\"8.8.4.4:77\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		wantGet: "{\"upstream_dns\":[\"8.8.8.8:77\",\"8.8.4.4:77\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name:    "bootstraps",
 		req:     "{\"bootstrap_dns\":[\"9.9.9.10\"]}",
 		wantSet: "",
-		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name:    "blocking_mode_good",
 		req:     "{\"blocking_mode\":\"refused\"}",
 		wantSet: "",
-		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"refused\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"refused\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name:    "blocking_mode_bad",
 		req:     "{\"blocking_mode\":\"custom_ip\"}",
 		wantSet: "blocking_mode: incorrect value\n",
-		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name:    "ratelimit",
 		req:     "{\"ratelimit\":6}",
 		wantSet: "",
-		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":6,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":6,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name:    "edns_cs_enabled",
 		req:     "{\"edns_cs_enabled\":true}",
 		wantSet: "",
-		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":true,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":true,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name:    "dnssec_enabled",
 		req:     "{\"dnssec_enabled\":true}",
 		wantSet: "",
-		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":true,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":true,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name:    "cache_size",
 		req:     "{\"cache_size\":1024}",
 		wantSet: "",
-		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":1024,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"\",\"cache_size\":1024,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name:    "upstream_mode_parallel",
 		req:     "{\"upstream_mode\":\"parallel\"}",
 		wantSet: "",
-		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"parallel\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"parallel\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name:    "upstream_mode_fastest_addr",
 		req:     "{\"upstream_mode\":\"fastest_addr\"}",
 		wantSet: "",
-		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"fastest_addr\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
+		wantGet: "{\"upstream_dns\":[\"8.8.8.8:53\",\"8.8.4.4:53\"],\"upstream_dns_file\":\"\",\"bootstrap_dns\":[\"9.9.9.10\",\"149.112.112.10\",\"2620:fe::10\",\"2620:fe::fe:10\"],\"protection_enabled\":true,\"ratelimit\":0,\"blocking_mode\":\"\",\"blocking_ipv4\":\"\",\"blocking_ipv6\":\"\",\"edns_cs_enabled\":false,\"dnssec_enabled\":false,\"disable_ipv6\":false,\"upstream_mode\":\"fastest_addr\",\"cache_size\":0,\"cache_ttl_min\":0,\"cache_ttl_max\":0,\"rebinding_protection_enabled\":false,\"rebinding_allowed_hosts\":[]}\n",
 	}, {
 		name:    "upstream_dns_bad",
 		req:     "{\"upstream_dns\":[\"\"]}",

internal/dnsforward/rebind.go

@@ -3,10 +3,13 @@
 package dnsforward
 
 import (
+	"fmt"
 	"net"
 	"strings"
 
+	"github.com/AdguardTeam/AdGuardHome/internal/dnsfilter"
 	"github.com/AdguardTeam/golibs/log"
+	"github.com/miekg/dns"
 )
 
 type dnsRebindChecker struct {
@@ -75,7 +78,7 @@ func (c *dnsRebindChecker) isRebindIP(ip net.IP) bool {
 // Checks DNS rebinding attacks
 // Note both whitelisted and cached hosts will bypass rebinding check (see: processFilteringAfterResponse()).
 func (s *Server) isResponseRebind(domain, host string) bool {
-	if !s.conf.RebindingEnabled {
+	if !s.conf.RebindingProtectionEnabled {
 		return false
 	}
 
@@ -93,3 +96,82 @@ func (s *Server) isResponseRebind(domain, host string) bool {
 	c := dnsRebindChecker{}
 	return c.isRebindHost(host)
 }
+
+func processRebindingFilteringAfterResponse(ctx *dnsContext) int {
+	s := ctx.srv
+	d := ctx.proxyCtx
+	res := ctx.result
+	var err error
+
+	if !ctx.responseFromUpstream || res.Reason == dnsfilter.ReasonRewrite {
+		return resultDone
+	}
+
+	originalRes := d.Res
+	ctx.result, err = s.preventRebindResponse(ctx)
+	if err != nil {
+		ctx.err = err
+		return resultError
+	}
+	if ctx.result != nil {
+		ctx.origResp = originalRes // matched by response
+	} else {
+		ctx.result = &dnsfilter.Result{}
+	}
+
+	return resultDone
+}
+
+func (s *Server) preventRebindResponse(ctx *dnsContext) (*dnsfilter.Result, error) {
+	d := ctx.proxyCtx
+
+	for _, a := range d.Res.Answer {
+		m := ""
+		domainName := ""
+		host := ""
+
+		switch v := a.(type) {
+		case *dns.CNAME:
+			host = strings.TrimSuffix(v.Target, ".")
+			domainName = v.Hdr.Name
+			m = fmt.Sprintf("DNSRebind: Checking CNAME %s for %s", v.Target, v.Hdr.Name)
+
+		case *dns.A:
+			host = v.A.String()
+			domainName = v.Hdr.Name
+			m = fmt.Sprintf("DNSRebind: Checking record A (%s) for %s", host, v.Hdr.Name)
+
+		case *dns.AAAA:
+			host = v.AAAA.String()
+			domainName = v.Hdr.Name
+			m = fmt.Sprintf("DNSRebind: Checking record AAAA (%s) for %s", host, v.Hdr.Name)
+
+		default:
+			continue
+		}
+
+		s.RLock()
+		if !s.conf.RebindingProtectionEnabled {
+			s.RUnlock()
+			continue
+		}
+
+		log.Debug(m)
+		blocked := s.isResponseRebind(domainName, host)
+		s.RUnlock()
+
+		if blocked {
+			res := &dnsfilter.Result{
+				IsFiltered: true,
+				Reason:     dnsfilter.FilteredRebind,
+				Rule:       "adguard-rebind-protection",
+			}
+
+			d.Res = s.genDNSFilterMessage(d, res)
+			log.Debug("DNSRebind: Matched %s by response: %s", d.Req.Question[0].Name, host)
+			return res, nil
+		}
+	}
+
+	return nil, nil
+}

internal/dnsforward/rebind_test.go

@@ -83,12 +83,12 @@ func TestIsResponseRebind(t *testing.T) {
 
 		"localhost",
 	} {
-		s.conf.RebindingEnabled = true
+		s.conf.RebindingProtectionEnabled = true
 		assert.True(t, s.isResponseRebind("example.com", host))
 		assert.False(t, s.isResponseRebind("totally-safe.com", host))
 		assert.False(t, s.isResponseRebind("absolutely.totally-safe.com", host))
 
-		s.conf.RebindingEnabled = false
+		s.conf.RebindingProtectionEnabled = false
 		assert.False(t, s.isResponseRebind("example.com", host))
 		assert.False(t, s.isResponseRebind("totally-safe.com", host))
 		assert.False(t, s.isResponseRebind("absolutely.totally-safe.com", host))
@@ -98,12 +98,12 @@ func TestIsResponseRebind(t *testing.T) {
 		"200.168.2.3",
 		"another-example.com",
 	} {
-		s.conf.RebindingEnabled = true
+		s.conf.RebindingProtectionEnabled = true
 		assert.False(t, s.isResponseRebind("example.com", host))
 		assert.False(t, s.isResponseRebind("totally-safe.com", host))
 		assert.False(t, s.isResponseRebind("absolutely.totally-legit.com", host))
 
-		s.conf.RebindingEnabled = false
+		s.conf.RebindingProtectionEnabled = false
 		assert.False(t, s.isResponseRebind("example.com", host))
 		assert.False(t, s.isResponseRebind("totally-safe.com", host))
 		assert.False(t, s.isResponseRebind("absolutely.totally-legit.com", host))