fix: generate a per-installation root CA

2026-08-17 19:47:10 +08:00 · 2026-08-12 20:04:29 +08:00
parent 7a67e76617
commit 2b8d1c9e3d
14 changed files with 454 additions and 89 deletions
@@ -1,6 +1,7 @@
 package certs

 import (
+	"bytes"
 	"crypto"
 	"crypto/ecdsa"
 	"crypto/ed25519"
@@ -9,33 +10,24 @@ import (
 	"crypto/tls"
 	"crypto/x509"
 	"crypto/x509/pkix"
-	_ "embed"
 	"encoding/pem"
 	"errors"
+	"fmt"
 	"math/big"
 	"net"
-	"os"
 	"strings"
 	"sync"
 	"time"
 )

-// embeddedCACertPEM 表示当前模块中的 embeddedCACertPEM 状态值。
-//
-//go:embed ca.crt
-var embeddedCACertPEM []byte
-
-// embeddedCAKeyPEM 表示当前模块中的 embeddedCAKeyPEM 状态值。
-//
-//go:embed ca.key
-var embeddedCAKeyPEM []byte
-
 // Manager 定义了当前模块中的 Manager 类型。
 type Manager struct {
 	// caCert 表示当前声明中的 caCert。
 	caCert *x509.Certificate
 	// caKey 表示当前声明中的 caKey。
 	caKey crypto.PrivateKey
+	// caCertPEM 保存可注入宿主信任存储的 CA 证书，不包含私钥。
+	caCertPEM []byte

 	// mu 表示当前声明中的 mu。
 	mu sync.Mutex
@@ -52,28 +44,26 @@ func NewManager(caCertPath, caKeyPath string) (*Manager, error) {
 	return NewManagerFromPEM(certPEM, keyPEM)
 }

-// NewEmbeddedManager 用于处理与 NewEmbeddedManager 相关的逻辑。
-func NewEmbeddedManager() (*Manager, error) {
-	return NewManagerFromPEM(embeddedCACertPEM, embeddedCAKeyPEM)
-}
-
-// EmbeddedCACertPEM 用于处理与 EmbeddedCACertPEM 相关的逻辑。
-func EmbeddedCACertPEM() []byte {
-	return cloneBytes(embeddedCACertPEM)
-}
-
-// EmbeddedCAKeyPEM 用于处理与 EmbeddedCAKeyPEM 相关的逻辑。
-func EmbeddedCAKeyPEM() []byte {
-	return cloneBytes(embeddedCAKeyPEM)
-}
-
 // NewManagerFromPEM 用于处理与 NewManagerFromPEM 相关的逻辑。
 func NewManagerFromPEM(caCertPEM, caKeyPEM []byte) (*Manager, error) {
 	caCert, caKey, err := loadCAFromPEM(caCertPEM, caKeyPEM)
 	if err != nil {
 		return nil, err
 	}
-	return &Manager{caCert: caCert, caKey: caKey, cache: make(map[string]*tls.Certificate)}, nil
+	return &Manager{
+		caCert:    caCert,
+		caKey:     caKey,
+		caCertPEM: cloneBytes(caCertPEM),
+		cache:     make(map[string]*tls.Certificate),
+	}, nil
+}
+
+// CACertPEM 返回当前 Manager 使用的 CA 证书。返回值不包含私钥。
+func (m *Manager) CACertPEM() []byte {
+	if m == nil {
+		return nil
+	}
+	return cloneBytes(m.caCertPEM)
 }

 // CATLSCertificate 用于处理与 CATLSCertificate 相关的逻辑。
@@ -185,19 +175,6 @@ func marshalPrivateKeyPEM(key any) ([]byte, error) {
 	}
 }

-// loadCAPEMFromFiles 用于处理与 loadCAPEMFromFiles 相关的逻辑。
-func loadCAPEMFromFiles(certPath, keyPath string) ([]byte, []byte, error) {
-	certPEM, err := os.ReadFile(certPath)
-	if err != nil {
-		return nil, nil, err
-	}
-	keyPEM, err := os.ReadFile(keyPath)
-	if err != nil {
-		return nil, nil, err
-	}
-	return certPEM, keyPEM, nil
-}
-
 // loadCAFromPEM 用于处理与 loadCAFromPEM 相关的逻辑。
 func loadCAFromPEM(certPEM, keyPEM []byte) (*x509.Certificate, crypto.PrivateKey, error) {
 	certBlock, _ := pem.Decode(certPEM)
@@ -214,28 +191,49 @@ func loadCAFromPEM(certPEM, keyPEM []byte) (*x509.Certificate, crypto.PrivateKey
 		return nil, nil, errors.New("invalid CA key PEM")
 	}

+	var caKey crypto.PrivateKey
 	switch keyBlock.Type {
 	case "RSA PRIVATE KEY":
 		key, err := x509.ParsePKCS1PrivateKey(keyBlock.Bytes)
 		if err != nil {
 			return nil, nil, err
 		}
-		return caCert, key, nil
+		caKey = key
 	case "EC PRIVATE KEY":
 		key, err := x509.ParseECPrivateKey(keyBlock.Bytes)
 		if err != nil {
 			return nil, nil, err
 		}
-		return caCert, key, nil
+		caKey = key
 	case "PRIVATE KEY":
 		key, err := x509.ParsePKCS8PrivateKey(keyBlock.Bytes)
 		if err != nil {
 			return nil, nil, err
 		}
-		return caCert, key, nil
+		caKey = key
 	default:
 		return nil, nil, errors.New("unsupported CA key format")
 	}
+
+	if !caCert.IsCA || !caCert.BasicConstraintsValid || caCert.KeyUsage&x509.KeyUsageCertSign == 0 {
+		return nil, nil, errors.New("certificate is not a valid signing CA")
+	}
+	signer, ok := caKey.(crypto.Signer)
+	if !ok {
+		return nil, nil, errors.New("CA private key cannot sign certificates")
+	}
+	certPublicKey, err := x509.MarshalPKIXPublicKey(caCert.PublicKey)
+	if err != nil {
+		return nil, nil, fmt.Errorf("marshal CA certificate public key: %w", err)
+	}
+	privatePublicKey, err := x509.MarshalPKIXPublicKey(signer.Public())
+	if err != nil {
+		return nil, nil, fmt.Errorf("marshal CA private key public key: %w", err)
+	}
+	if !bytes.Equal(certPublicKey, privatePublicKey) {
+		return nil, nil, errors.New("CA certificate and private key do not match")
+	}
+	return caCert, caKey, nil
 }

 // normalizeHost 用于处理与 normalizeHost 相关的逻辑。
@@ -1,27 +0,0 @@
-----BEGIN RSA PRIVATE KEY-----
-MIIEpAIBAAKCAQEAyh3jND/aFusuRjGTmhQtX2hkF1qroNjEEKCxWPlfprvdl8Tx
-upxNv1TQcm+K9KsS7OxnKYP4Qtv068XLbaCCGuoA/xpor6enrT85KulBq0j8z/g1
-y0VWxjz3xN9F9ND13h9yxDZCn76egbRkhFxpXow67jLsIlrqWDSltERlTKh2cJ1g
-hTRuQNSr7jtKQgFAR3aQ6dTzOP4fCOtLYn63jL4+YcxdGoK66tx8eFHq8oBLYvsc
-LNjjkaAHilZFwA4Jr7zHBofTRBg04eZum2UTaRqmSyT65ifXm4vRdQa4k1FS1gnq
-hPMhIjST8b6RkxvbLNmFpkOfI9eCMRpFG7y+NQIDAQABAoIBAATU9ZVOcHmLSkop
-zcBJerM09O2dAIziGb/XA55fqdJ728aQ0gGW0oIANlKCCaWjQFrTJP04VzNL/F01
-l5EpnOqlTPxMRpPqc2cAI677sBL29fpH0gtnvzUSiI7Xkp3RcAtNH6qCrJGSlkn+
-BMgoSGmW+yKuK3h/yWnt6kc2umA8fN+bHKhS3pI56PMW8qVnny9n92RaCA7Uf/4j
-XDewIreiH5jRqRwrPbOpjDFmv+W18LWZQiTwwxfY6sRZiZpsfsHidzfFGUFZXMlq
-2P3FCqoF4oMM1rRgBlHhDR7JHmSkFpZG639HJTXLllpyDbj3H86nsjIj9WZYKn+h
-B9k9bcECgYEA1HDzRCqoRZh6cL46KiYjv+LwmEKMa3nPb4ljywgLbRkzTMyVs0MK
-fDsDoTLFY9PBhveypU5gjTbQqtyBsDtbU+dH9Eks1FdL9P8bJf0ZOJFRiEB7uB4a
-z3V9tcXHwH4l2bCWbWThQGFwRudDAoY0EH89oSA/WHayjOKe1Wi4ovUCgYEA848B
-cYi+Qbkk+fOv9gSJn8KS1LH/jE28S/e7E4YkTfYUuu+7wr8bdRKUNpPIsLX0Fo9R
-KpJX0Oyjjady9n/8ARZRmD8Upl+F7Sl7Ro6F8+nfqQUrxbVDiIL3b+aZF+cDfFrB
-/xL5kyZZqTtFfP360tfYnlS6Sssd4E2Jsj0fJkECgYEA0gG+WbqZkgMDtwQ114jQ
-elZLZRkUWwKVjzsQDZssQHNTBS6RJh619M0Z73aTLvYcL+IZFdT/GVoAuYc2JRLo
-W28c8F6OFHMfwVeWbN1g20y8fqbQJtiLxF3vIYwcxStvG123tvisu8oXBeCDm7Ez
-MsO2FtwcAsWECEXWojzdmSkCgYEA18GvPawtHnuszd+Z2Q5b/DKZb+Hex6N1Ura5
-+qmyL333D0Kfyf0RjbxPn6l690+4UuPSuyu4r1Nx72KO7N6jlzL2RTBcUqX8NgOx
-OOe4skJT5561EAdrM9sQ5wgYRpxW8ipUAGoGvNwUQV5ISFmVgIHFWz0jam5UoQcP
-G94ZYgECgYBN4PB8BuAwMRqhTCLL5RJKtcdC/Ls9xdWrmswtQQ4OSBUTLGdeMhEN
-E23F0d+NdtiTWDYRDJ7z6KAF8CcOwWMt2sNbrxgNRuDzyfLqbuVLOM8iY3xA50Nl
-clZWujKILWp47+gA6/AqJLv2lA2LK8gM8zYzzm/nCuLCBLYH/hOiCA==
-----END RSA PRIVATE KEY-----
@@ -0,0 +1,191 @@
+package certs
+
+import (
+	"crypto/rand"
+	"crypto/rsa"
+	"crypto/sha256"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/hex"
+	"encoding/pem"
+	"errors"
+	"fmt"
+	"math/big"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+const legacySharedCASHA256 = "836E6BB84F6C3E63316DBB4EC257223AF09F7490E7AAE09030B8515ED61EE9FF"
+
+// LoadOrCreateManager loads the installation-specific CA, generating it on
+// first run. The private key is persisted only in the supplied local path.
+func LoadOrCreateManager(certPath, keyPath string) (*Manager, []byte, error) {
+	certPEM, certErr := os.ReadFile(certPath)
+	keyPEM, keyErr := os.ReadFile(keyPath)
+
+	if certErr == nil && isLegacySharedCA(certPEM) {
+		return generateAndPersistManager(certPath, keyPath)
+	}
+	if certErr == nil && keyErr == nil {
+		manager, err := NewManagerFromPEM(certPEM, keyPEM)
+		if err != nil {
+			return nil, nil, fmt.Errorf("load installation CA: %w", err)
+		}
+		if err := os.Chmod(keyPath, 0o600); err != nil {
+			return nil, nil, fmt.Errorf("restrict installation CA private key permissions: %w", err)
+		}
+		return manager, manager.CACertPEM(), nil
+	}
+	if errors.Is(certErr, os.ErrNotExist) && errors.Is(keyErr, os.ErrNotExist) {
+		return generateAndPersistManager(certPath, keyPath)
+	}
+	// A key without a certificate cannot have been installed as a trusted root.
+	// This is safe to recover if the first-run write was interrupted.
+	if errors.Is(certErr, os.ErrNotExist) && keyErr == nil {
+		return generateAndPersistManager(certPath, keyPath)
+	}
+	if certErr != nil && !errors.Is(certErr, os.ErrNotExist) {
+		return nil, nil, fmt.Errorf("read installation CA certificate: %w", certErr)
+	}
+	if keyErr != nil && !errors.Is(keyErr, os.ErrNotExist) {
+		return nil, nil, fmt.Errorf("read installation CA private key: %w", keyErr)
+	}
+	return nil, nil, errors.New("installation CA is incomplete; both certificate and private key are required")
+}
+
+// NewGeneratedManager creates an in-memory CA suitable for short-lived tools.
+func NewGeneratedManager() (*Manager, []byte, error) {
+	certPEM, keyPEM, err := generateCA()
+	if err != nil {
+		return nil, nil, err
+	}
+	manager, err := NewManagerFromPEM(certPEM, keyPEM)
+	if err != nil {
+		return nil, nil, err
+	}
+	return manager, manager.CACertPEM(), nil
+}
+
+func generateAndPersistManager(certPath, keyPath string) (*Manager, []byte, error) {
+	if filepath.Dir(certPath) != filepath.Dir(keyPath) {
+		return nil, nil, errors.New("installation CA certificate and key must share a directory")
+	}
+	certPEM, keyPEM, err := generateCA()
+	if err != nil {
+		return nil, nil, err
+	}
+	if err := os.MkdirAll(filepath.Dir(certPath), 0o700); err != nil {
+		return nil, nil, fmt.Errorf("create installation CA directory: %w", err)
+	}
+	// Write the private key first so a crash cannot leave a new certificate
+	// without the signing key needed by the proxy.
+	if err := writeLocalCAFile(keyPath, keyPEM, 0o600); err != nil {
+		return nil, nil, fmt.Errorf("persist installation CA private key: %w", err)
+	}
+	if err := writeLocalCAFile(certPath, certPEM, 0o644); err != nil {
+		return nil, nil, fmt.Errorf("persist installation CA certificate: %w", err)
+	}
+	manager, err := NewManagerFromPEM(certPEM, keyPEM)
+	if err != nil {
+		return nil, nil, err
+	}
+	return manager, manager.CACertPEM(), nil
+}
+
+func generateCA() ([]byte, []byte, error) {
+	privateKey, err := rsa.GenerateKey(rand.Reader, 3072)
+	if err != nil {
+		return nil, nil, fmt.Errorf("generate installation CA private key: %w", err)
+	}
+	serial, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 128))
+	if err != nil {
+		return nil, nil, fmt.Errorf("generate installation CA serial: %w", err)
+	}
+	publicKeyDER, err := x509.MarshalPKIXPublicKey(&privateKey.PublicKey)
+	if err != nil {
+		return nil, nil, fmt.Errorf("marshal installation CA public key: %w", err)
+	}
+	subjectKeyID := sha256.Sum256(publicKeyDER)
+	now := time.Now()
+	template := &x509.Certificate{
+		SerialNumber: serial,
+		Subject: pkix.Name{
+			CommonName:   "Cursor BYOK Local CA",
+			Organization: []string{"Cursor BYOK"},
+		},
+		NotBefore:             now.Add(-5 * time.Minute),
+		NotAfter:              now.AddDate(10, 0, 0),
+		KeyUsage:              x509.KeyUsageDigitalSignature | x509.KeyUsageCertSign | x509.KeyUsageCRLSign,
+		BasicConstraintsValid: true,
+		IsCA:                  true,
+		MaxPathLen:            0,
+		MaxPathLenZero:        true,
+		SubjectKeyId:          append([]byte(nil), subjectKeyID[:20]...),
+	}
+	der, err := x509.CreateCertificate(rand.Reader, template, template, &privateKey.PublicKey, privateKey)
+	if err != nil {
+		return nil, nil, fmt.Errorf("create installation CA certificate: %w", err)
+	}
+	certPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der})
+	keyPEM := pem.EncodeToMemory(&pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(privateKey)})
+	return certPEM, keyPEM, nil
+}
+
+func writeLocalCAFile(path string, data []byte, mode os.FileMode) error {
+	temp, err := os.CreateTemp(filepath.Dir(path), ".ca-*")
+	if err != nil {
+		return err
+	}
+	tempPath := temp.Name()
+	defer os.Remove(tempPath)
+	if err := temp.Chmod(mode); err != nil {
+		_ = temp.Close()
+		return err
+	}
+	if _, err := temp.Write(data); err != nil {
+		_ = temp.Close()
+		return err
+	}
+	if err := temp.Sync(); err != nil {
+		_ = temp.Close()
+		return err
+	}
+	if err := temp.Close(); err != nil {
+		return err
+	}
+	if err := os.Remove(path); err != nil && !errors.Is(err, os.ErrNotExist) {
+		return err
+	}
+	if err := os.Rename(tempPath, path); err != nil {
+		return err
+	}
+	return os.Chmod(path, mode)
+}
+
+func isLegacySharedCA(certPEM []byte) bool {
+	block, _ := pem.Decode(certPEM)
+	if block == nil {
+		return false
+	}
+	cert, err := x509.ParseCertificate(block.Bytes)
+	if err != nil {
+		return false
+	}
+	sum := sha256.Sum256(cert.Raw)
+	return strings.EqualFold(hex.EncodeToString(sum[:]), legacySharedCASHA256)
+}
+
+// loadCAPEMFromFiles reads an explicitly supplied CA pair.
+func loadCAPEMFromFiles(certPath, keyPath string) ([]byte, []byte, error) {
+	certPEM, err := os.ReadFile(certPath)
+	if err != nil {
+		return nil, nil, err
+	}
+	keyPEM, err := os.ReadFile(keyPath)
+	if err != nil {
+		return nil, nil, err
+	}
+	return certPEM, keyPEM, nil
+}
@@ -0,0 +1,125 @@
+package certs
+
+import (
+	"bytes"
+	"crypto/x509"
+	"encoding/pem"
+	"os"
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+func TestLoadOrCreateManagerPersistsAndReusesInstallationCA(t *testing.T) {
+	dir := t.TempDir()
+	certPath := filepath.Join(dir, "ca.crt")
+	keyPath := filepath.Join(dir, "ca.key")
+
+	manager, certPEM, err := LoadOrCreateManager(certPath, keyPath)
+	if err != nil {
+		t.Fatalf("LoadOrCreateManager() error = %v", err)
+	}
+	if isLegacySharedCA(certPEM) {
+		t.Fatal("generated CA reused the legacy shared certificate")
+	}
+	keyInfo, err := os.Stat(keyPath)
+	if err != nil {
+		t.Fatalf("stat private key: %v", err)
+	}
+	if runtime.GOOS != "windows" && keyInfo.Mode().Perm() != 0o600 {
+		t.Fatalf("private key mode = %o, want 600", keyInfo.Mode().Perm())
+	}
+
+	leaf, err := manager.CertificateForServerName("api2.cursor.sh")
+	if err != nil {
+		t.Fatalf("CertificateForServerName() error = %v", err)
+	}
+	ca := parseCertificatePEM(t, certPEM)
+	roots := x509.NewCertPool()
+	roots.AddCert(ca)
+	if _, err := leaf.Leaf.Verify(x509.VerifyOptions{DNSName: "api2.cursor.sh", Roots: roots}); err != nil {
+		t.Fatalf("verify generated leaf: %v", err)
+	}
+
+	_, reusedCertPEM, err := LoadOrCreateManager(certPath, keyPath)
+	if err != nil {
+		t.Fatalf("second LoadOrCreateManager() error = %v", err)
+	}
+	if !bytes.Equal(certPEM, reusedCertPEM) {
+		t.Fatal("installation CA changed between loads")
+	}
+}
+
+func TestLoadOrCreateManagerCreatesUniqueCAsPerInstallation(t *testing.T) {
+	firstDir := t.TempDir()
+	secondDir := t.TempDir()
+	_, firstCert, err := LoadOrCreateManager(filepath.Join(firstDir, "ca.crt"), filepath.Join(firstDir, "ca.key"))
+	if err != nil {
+		t.Fatalf("create first CA: %v", err)
+	}
+	_, secondCert, err := LoadOrCreateManager(filepath.Join(secondDir, "ca.crt"), filepath.Join(secondDir, "ca.key"))
+	if err != nil {
+		t.Fatalf("create second CA: %v", err)
+	}
+	if bytes.Equal(firstCert, secondCert) {
+		t.Fatal("separate installations received the same CA certificate")
+	}
+}
+
+func TestLoadOrCreateManagerReplacesLegacySharedCertificate(t *testing.T) {
+	dir := t.TempDir()
+	certPath := filepath.Join(dir, "ca.crt")
+	keyPath := filepath.Join(dir, "ca.key")
+	legacyCert, err := os.ReadFile(filepath.Join("testdata", "legacy_shared_ca.crt"))
+	if err != nil {
+		t.Fatalf("read legacy certificate fixture: %v", err)
+	}
+	if !isLegacySharedCA(legacyCert) {
+		t.Fatal("legacy certificate fixture fingerprint changed")
+	}
+	if err := os.WriteFile(certPath, legacyCert, 0o644); err != nil {
+		t.Fatalf("write legacy certificate: %v", err)
+	}
+
+	_, generatedCert, err := LoadOrCreateManager(certPath, keyPath)
+	if err != nil {
+		t.Fatalf("migrate legacy certificate: %v", err)
+	}
+	if bytes.Equal(legacyCert, generatedCert) || isLegacySharedCA(generatedCert) {
+		t.Fatal("legacy shared certificate was not replaced")
+	}
+	if _, err := os.Stat(keyPath); err != nil {
+		t.Fatalf("generated private key missing: %v", err)
+	}
+}
+
+func TestNewManagerFromPEMRejectsMismatchedKey(t *testing.T) {
+	firstDir := t.TempDir()
+	secondDir := t.TempDir()
+	_, _, err := LoadOrCreateManager(filepath.Join(firstDir, "ca.crt"), filepath.Join(firstDir, "ca.key"))
+	if err != nil {
+		t.Fatalf("create first CA: %v", err)
+	}
+	_, _, err = LoadOrCreateManager(filepath.Join(secondDir, "ca.crt"), filepath.Join(secondDir, "ca.key"))
+	if err != nil {
+		t.Fatalf("create second CA: %v", err)
+	}
+	certPEM, _ := os.ReadFile(filepath.Join(firstDir, "ca.crt"))
+	keyPEM, _ := os.ReadFile(filepath.Join(secondDir, "ca.key"))
+	if _, err := NewManagerFromPEM(certPEM, keyPEM); err == nil {
+		t.Fatal("NewManagerFromPEM() accepted a mismatched private key")
+	}
+}
+
+func parseCertificatePEM(t *testing.T, certPEM []byte) *x509.Certificate {
+	t.Helper()
+	block, _ := pem.Decode(certPEM)
+	if block == nil {
+		t.Fatal("certificate PEM is invalid")
+	}
+	cert, err := x509.ParseCertificate(block.Bytes)
+	if err != nil {
+		t.Fatalf("parse certificate: %v", err)
+	}
+	return cert
+}