core: Add full TSIG verification in DoH3 transport (#8044)

* core: Add full TSIG verification in DoH3 transport

This This PR add full TSIG verification in DoH3 using dns.TsigVerify() - 7943

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

* Fix

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

---------

Signed-off-by: Yong Tang <yong.tang.github@outlook.com>

core/dnsserver/server_https3.go

@@ -18,6 +18,7 @@ import (
 	"github.com/coredns/coredns/plugin/pkg/reuseport"
 	"github.com/coredns/coredns/plugin/pkg/transport"
 
+	"github.com/miekg/dns"
 	"github.com/quic-go/quic-go"
 	"github.com/quic-go/quic-go/http3"
 )
@@ -172,7 +173,7 @@ func (s *ServerHTTPS3) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	msg, err := doh.RequestToMsg(r)
+	msg, raw, err := doh.RequestToMsgWire(r)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		s.countResponse(http.StatusBadRequest)
@@ -188,6 +189,16 @@ func (s *ServerHTTPS3) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		request: r,
 	}
 
+	if tsig := msg.IsTsig(); tsig != nil {
+		if s.tsigSecret == nil {
+			dw.tsigStatus = dns.ErrSecret
+		} else if secret, ok := s.tsigSecret[tsig.Hdr.Name]; !ok {
+			dw.tsigStatus = dns.ErrSecret
+		} else {
+			dw.tsigStatus = dns.TsigVerify(raw, secret, "", false)
+		}
+	}
+
 	ctx := context.WithValue(r.Context(), Key{}, s.Server)
 	ctx = context.WithValue(ctx, LoopKey{}, 0)
 	ctx = context.WithValue(ctx, HTTPRequestKey{}, r)

core/dnsserver/server_https3_test.go

@@ -3,13 +3,25 @@ package dnsserver
 import (
 	"bytes"
 	"crypto/tls"
+	"errors"
+	"io"
 	"net/http"
 	"net/http/httptest"
+	"strings"
 	"testing"
+	"time"
+
+	"github.com/coredns/coredns/plugin"
 
 	"github.com/miekg/dns"
 )
 
+const (
+	testTSIGKeyNameHTTPS3     = "tsig-key."
+	testTSIGSecretHTTPS3      = "MTIzNA=="
+	testTSIGWrongSecretHTTPS3 = "NTY3OA=="
+)
+
 func testServerHTTPS3(t *testing.T, path string, validator func(*http.Request) bool) *http.Response {
 	t.Helper()
 	c := Config{
@@ -139,3 +151,178 @@ func TestNewServerHTTPS3ZeroLimits(t *testing.T) {
 		t.Errorf("Expected quicConfig.MaxIncomingStreams = 0 (QUIC default), got %d", server.quicConfig.MaxIncomingStreams)
 	}
 }
+
+func testConfigWithTSIGCheckPluginHTTPS3(t *testing.T, check func(*testing.T, error)) *Config {
+	t.Helper()
+
+	c := &Config{
+		Zone:        "example.com.",
+		Transport:   "https3",
+		TLSConfig:   &tls.Config{},
+		ListenHosts: []string{"127.0.0.1"},
+		Port:        "443",
+		TsigSecret: map[string]string{
+			testTSIGKeyNameHTTPS3: testTSIGSecretHTTPS3,
+		},
+	}
+	c.AddPlugin(func(_next plugin.Handler) plugin.Handler {
+		return tsigStatusCheckPlugin{t: t, check: check}
+	})
+	return c
+}
+
+func testServerHTTPS3Msg(t *testing.T, cfg *Config, req *dns.Msg) *dns.Msg {
+	t.Helper()
+
+	s, err := NewServerHTTPS3("127.0.0.1:443", []*Config{cfg})
+	if err != nil {
+		t.Fatal("could not create HTTPS3 server:", err)
+	}
+
+	buf, err := req.Pack()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	r := httptest.NewRequest(http.MethodPost, "/dns-query", bytes.NewReader(buf))
+	r.RemoteAddr = "127.0.0.1:12345"
+	w := httptest.NewRecorder()
+
+	s.ServeHTTP(w, r)
+
+	res := w.Result()
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusOK {
+		t.Fatalf("unexpected HTTP status: got %d", res.StatusCode)
+	}
+
+	body, err := io.ReadAll(res.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	m := new(dns.Msg)
+	if err := m.Unpack(body); err != nil {
+		t.Fatal(err)
+	}
+	return m
+}
+
+func testServerHTTPS3Raw(t *testing.T, cfg *Config, buf []byte) *dns.Msg {
+	t.Helper()
+
+	s, err := NewServerHTTPS3("127.0.0.1:443", []*Config{cfg})
+	if err != nil {
+		t.Fatal("could not create HTTPS3 server:", err)
+	}
+
+	r := httptest.NewRequest(http.MethodPost, "/dns-query", bytes.NewReader(buf))
+	r.RemoteAddr = "127.0.0.1:12345"
+	w := httptest.NewRecorder()
+
+	s.ServeHTTP(w, r)
+
+	res := w.Result()
+	defer res.Body.Close()
+
+	if res.StatusCode != http.StatusOK {
+		t.Fatalf("unexpected HTTP status: got %d", res.StatusCode)
+	}
+
+	body, err := io.ReadAll(res.Body)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	m := new(dns.Msg)
+	if err := m.Unpack(body); err != nil {
+		t.Fatal(err)
+	}
+	return m
+}
+
+func forgedTSIGMsgHTTPS3() *dns.Msg {
+	m := new(dns.Msg)
+	m.SetQuestion("example.com.", dns.TypeA)
+
+	m.Extra = append(m.Extra, &dns.TSIG{
+		Hdr: dns.RR_Header{
+			Name:   "bogus-key.",
+			Rrtype: dns.TypeTSIG,
+			Class:  dns.ClassANY,
+			Ttl:    0,
+		},
+		Algorithm:  dns.HmacSHA256,
+		TimeSigned: uint64(time.Now().Unix()),
+		Fudge:      300,
+		MACSize:    32,
+		MAC:        strings.Repeat("00", 32),
+		OrigId:     m.Id,
+		Error:      dns.RcodeSuccess,
+	})
+	return m
+}
+
+func TestServeHTTP3RejectsUnsignedTSIGRequiredRequest(t *testing.T) {
+	cfg := testConfigWithTSIGCheckPluginHTTPS3(t, func(t *testing.T, err error) {
+		t.Helper()
+		if err != nil {
+			t.Fatalf("expected nil TsigStatus for unsigned request, got %v", err)
+		}
+	})
+
+	m := new(dns.Msg)
+	m.SetQuestion("example.com.", dns.TypeA)
+	resp := testServerHTTPS3Msg(t, cfg, m)
+
+	if resp.Rcode != dns.RcodeSuccess {
+		t.Fatalf("expected NOERROR response from plugin, got %s", dns.RcodeToString[resp.Rcode])
+	}
+}
+
+func TestServeHTTP3RejectsTSIGWithUnknownKey(t *testing.T) {
+	cfg := testConfigWithTSIGCheckPluginHTTPS3(t, func(t *testing.T, err error) {
+		t.Helper()
+		if !errors.Is(err, dns.ErrSecret) {
+			t.Fatalf("expected dns.ErrSecret for unknown TSIG key, got %v", err)
+		}
+	})
+
+	resp := testServerHTTPS3Msg(t, cfg, forgedTSIGMsgHTTPS3())
+	if resp.Rcode != dns.RcodeSuccess {
+		t.Fatalf("expected NOERROR response from plugin, got %s", dns.RcodeToString[resp.Rcode])
+	}
+}
+
+func TestServeHTTP3RejectsTSIGWithBadMAC(t *testing.T) {
+	cfg := testConfigWithTSIGCheckPluginHTTPS3(t, func(t *testing.T, err error) {
+		t.Helper()
+		if err == nil {
+			t.Fatal("expected non-nil TsigStatus for bad TSIG MAC")
+		}
+	})
+
+	buf := mustPackSignedTSIGQuery(t, testTSIGKeyNameHTTPS3, testTSIGWrongSecretHTTPS3, time.Now().Unix())
+	resp := testServerHTTPS3Raw(t, cfg, buf)
+
+	if resp.Rcode != dns.RcodeSuccess {
+		t.Fatalf("expected NOERROR response from plugin, got %s", dns.RcodeToString[resp.Rcode])
+	}
+}
+
+func TestServeHTTP3AcceptsValidTSIG(t *testing.T) {
+	cfg := testConfigWithTSIGCheckPluginHTTPS3(t, func(t *testing.T, err error) {
+		t.Helper()
+		if err != nil {
+			t.Fatalf("expected nil TsigStatus for valid TSIG, got %v", err)
+		}
+	})
+
+	buf := mustPackSignedTSIGQuery(t, testTSIGKeyNameHTTPS3, testTSIGSecretHTTPS3, time.Now().Unix())
+	resp := testServerHTTPS3Raw(t, cfg, buf)
+
+	if resp.Rcode != dns.RcodeSuccess {
+		t.Fatalf("expected NOERROR response from plugin, got %s", dns.RcodeToString[resp.Rcode])
+	}
+}