feat(client): verify server certificates against the system root store (#5546)

transport.tls.trustedCaFile is installed as RootCAs, and omitting it sets InsecureSkipVerify, so system-root verification cannot be selected directly. Add an opt-in transport.tls.useSystemRoots that enables certificate verification with RootCAs nil when no trusted CA file is set, allowing Go to use system roots and native verification on macOS and Windows. Defaults are unchanged.
2026-10-18 14:08:05 +08:00
parent 954f918d0c
commit 7441443134
8 changed files with 176 additions and 6 deletions
@@ -0,0 +1,139 @@
+// Copyright 2026 The frp Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package transport
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/tls"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/pem"
+	"errors"
+	"math/big"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func newSelfSignedCert(t *testing.T) (tls.Certificate, []byte) {
+	t.Helper()
+
+	key, err := rsa.GenerateKey(rand.Reader, 2048)
+	require.NoError(t, err)
+
+	template := x509.Certificate{
+		SerialNumber: big.NewInt(1),
+		Subject:      pkix.Name{CommonName: "localhost"},
+		DNSNames:     []string{"localhost"},
+		NotBefore:    time.Now().Add(-time.Hour),
+		NotAfter:     time.Now().Add(time.Hour),
+	}
+	certDER, err := x509.CreateCertificate(rand.Reader, &template, &template, &key.PublicKey, key)
+	require.NoError(t, err)
+
+	certPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: certDER})
+	keyPEM := pem.EncodeToMemory(&pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(key)})
+
+	cert, err := tls.X509KeyPair(certPEM, keyPEM)
+	require.NoError(t, err)
+	return cert, certPEM
+}
+
+func TestNewClientTLSConfigVerification(t *testing.T) {
+	_, caPEM := newSelfSignedCert(t)
+	caFile := filepath.Join(t.TempDir(), "ca.crt")
+	require.NoError(t, os.WriteFile(caFile, caPEM, 0o600))
+
+	tests := []struct {
+		name               string
+		caPath             string
+		useSystemRoots     bool
+		insecureSkipVerify bool
+		rootCAsSet         bool
+	}{
+		{
+			name:               "no trusted ca file, no system roots",
+			insecureSkipVerify: true,
+		},
+		{
+			name:           "system roots",
+			useSystemRoots: true,
+		},
+		{
+			name:       "trusted ca file",
+			caPath:     caFile,
+			rootCAsSet: true,
+		},
+		{
+			name:           "trusted ca file takes precedence over system roots",
+			caPath:         caFile,
+			useSystemRoots: true,
+			rootCAsSet:     true,
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			require := require.New(t)
+
+			cfg, err := NewClientTLSConfigWithSystemRoots("", "", test.caPath, "example.com", test.useSystemRoots)
+			require.NoError(err)
+			require.Equal("example.com", cfg.ServerName)
+			require.Equal(test.insecureSkipVerify, cfg.InsecureSkipVerify)
+			require.Equal(test.rootCAsSet, cfg.RootCAs != nil)
+		})
+	}
+}
+
+func TestClientTLSConfigHandshakeWithUntrustedServer(t *testing.T) {
+	require := require.New(t)
+
+	cert, _ := newSelfSignedCert(t)
+	ln, err := tls.Listen("tcp", "127.0.0.1:0", &tls.Config{Certificates: []tls.Certificate{cert}})
+	require.NoError(err)
+	t.Cleanup(func() { _ = ln.Close() })
+
+	go func() {
+		for {
+			conn, err := ln.Accept()
+			if err != nil {
+				return
+			}
+			_ = conn.(*tls.Conn).Handshake()
+			_ = conn.Close()
+		}
+	}()
+
+	dial := func(useSystemRoots bool) error {
+		cfg, err := NewClientTLSConfigWithSystemRoots("", "", "", "localhost", useSystemRoots)
+		require.NoError(err)
+		conn, err := tls.Dial("tcp", ln.Addr().String(), cfg)
+		if err != nil {
+			return err
+		}
+		return conn.Close()
+	}
+
+	require.NoError(dial(false))
+
+	err = dial(true)
+	require.Error(err)
+	var verificationErr *tls.CertificateVerificationError
+	require.True(errors.As(err, &verificationErr), "expected a certificate verification error, got %v", err)
+}