gitea/services/auth/source/oauth2/jwtsigningkey.go

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// Copyright 2021 The Gitea Authors. All rights reserved.
// SPDX-License-Identifier: MIT
package oauth2
import (
"crypto/ecdsa"
"crypto/ed25519"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"encoding/base64"
"encoding/pem"
"fmt"
"math/big"
"os"
"path/filepath"
"strings"
"code.gitea.io/gitea/modules/log"
"code.gitea.io/gitea/modules/setting"
"code.gitea.io/gitea/modules/util"
"github.com/golang-jwt/jwt/v4"
"github.com/minio/sha256-simd"
)
// ErrInvalidAlgorithmType represents an invalid algorithm error.
type ErrInvalidAlgorithmType struct {
Algorithm string
}
func (err ErrInvalidAlgorithmType) Error() string {
return fmt.Sprintf("JWT signing algorithm is not supported: %s", err.Algorithm)
}
// JWTSigningKey represents a algorithm/key pair to sign JWTs
type JWTSigningKey interface {
IsSymmetric() bool
SigningMethod() jwt.SigningMethod
SignKey() interface{}
VerifyKey() interface{}
ToJWK() (map[string]string, error)
PreProcessToken(*jwt.Token)
}
type hmacSigningKey struct {
signingMethod jwt.SigningMethod
secret []byte
}
func (key hmacSigningKey) IsSymmetric() bool {
return true
}
func (key hmacSigningKey) SigningMethod() jwt.SigningMethod {
return key.signingMethod
}
func (key hmacSigningKey) SignKey() interface{} {
return key.secret
}
func (key hmacSigningKey) VerifyKey() interface{} {
return key.secret
}
func (key hmacSigningKey) ToJWK() (map[string]string, error) {
return map[string]string{
"kty": "oct",
"alg": key.SigningMethod().Alg(),
}, nil
}
func (key hmacSigningKey) PreProcessToken(*jwt.Token) {}
type rsaSingingKey struct {
signingMethod jwt.SigningMethod
key *rsa.PrivateKey
id string
}
func newRSASingingKey(signingMethod jwt.SigningMethod, key *rsa.PrivateKey) (rsaSingingKey, error) {
kid, err := createPublicKeyFingerprint(key.Public().(*rsa.PublicKey))
if err != nil {
return rsaSingingKey{}, err
}
return rsaSingingKey{
signingMethod,
key,
base64.RawURLEncoding.EncodeToString(kid),
}, nil
}
func (key rsaSingingKey) IsSymmetric() bool {
return false
}
func (key rsaSingingKey) SigningMethod() jwt.SigningMethod {
return key.signingMethod
}
func (key rsaSingingKey) SignKey() interface{} {
return key.key
}
func (key rsaSingingKey) VerifyKey() interface{} {
return key.key.Public()
}
func (key rsaSingingKey) ToJWK() (map[string]string, error) {
pubKey := key.key.Public().(*rsa.PublicKey)
return map[string]string{
"kty": "RSA",
"alg": key.SigningMethod().Alg(),
"kid": key.id,
"e": base64.RawURLEncoding.EncodeToString(big.NewInt(int64(pubKey.E)).Bytes()),
"n": base64.RawURLEncoding.EncodeToString(pubKey.N.Bytes()),
}, nil
}
func (key rsaSingingKey) PreProcessToken(token *jwt.Token) {
token.Header["kid"] = key.id
}
type eddsaSigningKey struct {
signingMethod jwt.SigningMethod
key ed25519.PrivateKey
id string
}
func newEdDSASingingKey(signingMethod jwt.SigningMethod, key ed25519.PrivateKey) (eddsaSigningKey, error) {
kid, err := createPublicKeyFingerprint(key.Public().(ed25519.PublicKey))
if err != nil {
return eddsaSigningKey{}, err
}
return eddsaSigningKey{
signingMethod,
key,
base64.RawURLEncoding.EncodeToString(kid),
}, nil
}
func (key eddsaSigningKey) IsSymmetric() bool {
return false
}
func (key eddsaSigningKey) SigningMethod() jwt.SigningMethod {
return key.signingMethod
}
func (key eddsaSigningKey) SignKey() interface{} {
return key.key
}
func (key eddsaSigningKey) VerifyKey() interface{} {
return key.key.Public()
}
func (key eddsaSigningKey) ToJWK() (map[string]string, error) {
pubKey := key.key.Public().(ed25519.PublicKey)
return map[string]string{
"alg": key.SigningMethod().Alg(),
"kid": key.id,
"kty": "OKP",
"crv": "Ed25519",
"x": base64.RawURLEncoding.EncodeToString(pubKey),
}, nil
}
func (key eddsaSigningKey) PreProcessToken(token *jwt.Token) {
token.Header["kid"] = key.id
}
type ecdsaSingingKey struct {
signingMethod jwt.SigningMethod
key *ecdsa.PrivateKey
id string
}
func newECDSASingingKey(signingMethod jwt.SigningMethod, key *ecdsa.PrivateKey) (ecdsaSingingKey, error) {
kid, err := createPublicKeyFingerprint(key.Public().(*ecdsa.PublicKey))
if err != nil {
return ecdsaSingingKey{}, err
}
return ecdsaSingingKey{
signingMethod,
key,
base64.RawURLEncoding.EncodeToString(kid),
}, nil
}
func (key ecdsaSingingKey) IsSymmetric() bool {
return false
}
func (key ecdsaSingingKey) SigningMethod() jwt.SigningMethod {
return key.signingMethod
}
func (key ecdsaSingingKey) SignKey() interface{} {
return key.key
}
func (key ecdsaSingingKey) VerifyKey() interface{} {
return key.key.Public()
}
func (key ecdsaSingingKey) ToJWK() (map[string]string, error) {
pubKey := key.key.Public().(*ecdsa.PublicKey)
return map[string]string{
"kty": "EC",
"alg": key.SigningMethod().Alg(),
"kid": key.id,
"crv": pubKey.Params().Name,
"x": base64.RawURLEncoding.EncodeToString(pubKey.X.Bytes()),
"y": base64.RawURLEncoding.EncodeToString(pubKey.Y.Bytes()),
}, nil
}
func (key ecdsaSingingKey) PreProcessToken(token *jwt.Token) {
token.Header["kid"] = key.id
}
// createPublicKeyFingerprint creates a fingerprint of the given key.
// The fingerprint is the sha256 sum of the PKIX structure of the key.
func createPublicKeyFingerprint(key interface{}) ([]byte, error) {
bytes, err := x509.MarshalPKIXPublicKey(key)
if err != nil {
return nil, err
}
checksum := sha256.Sum256(bytes)
return checksum[:], nil
}
// CreateJWTSigningKey creates a signing key from an algorithm / key pair.
func CreateJWTSigningKey(algorithm string, key interface{}) (JWTSigningKey, error) {
var signingMethod jwt.SigningMethod
switch algorithm {
case "HS256":
signingMethod = jwt.SigningMethodHS256
case "HS384":
signingMethod = jwt.SigningMethodHS384
case "HS512":
signingMethod = jwt.SigningMethodHS512
case "RS256":
signingMethod = jwt.SigningMethodRS256
case "RS384":
signingMethod = jwt.SigningMethodRS384
case "RS512":
signingMethod = jwt.SigningMethodRS512
case "ES256":
signingMethod = jwt.SigningMethodES256
case "ES384":
signingMethod = jwt.SigningMethodES384
case "ES512":
signingMethod = jwt.SigningMethodES512
case "EdDSA":
signingMethod = jwt.SigningMethodEdDSA
default:
return nil, ErrInvalidAlgorithmType{algorithm}
}
switch signingMethod.(type) {
case *jwt.SigningMethodEd25519:
privateKey, ok := key.(ed25519.PrivateKey)
if !ok {
return nil, jwt.ErrInvalidKeyType
}
return newEdDSASingingKey(signingMethod, privateKey)
case *jwt.SigningMethodECDSA:
privateKey, ok := key.(*ecdsa.PrivateKey)
if !ok {
return nil, jwt.ErrInvalidKeyType
}
return newECDSASingingKey(signingMethod, privateKey)
case *jwt.SigningMethodRSA:
privateKey, ok := key.(*rsa.PrivateKey)
if !ok {
return nil, jwt.ErrInvalidKeyType
}
return newRSASingingKey(signingMethod, privateKey)
default:
secret, ok := key.([]byte)
if !ok {
return nil, jwt.ErrInvalidKeyType
}
return hmacSigningKey{signingMethod, secret}, nil
}
}
// DefaultSigningKey is the default signing key for JWTs.
var DefaultSigningKey JWTSigningKey
// InitSigningKey creates the default signing key from settings or creates a random key.
func InitSigningKey() error {
var err error
var key interface{}
switch setting.OAuth2.JWTSigningAlgorithm {
case "HS256":
fallthrough
case "HS384":
fallthrough
case "HS512":
key, err = loadSymmetricKey()
case "RS256":
fallthrough
case "RS384":
fallthrough
case "RS512":
fallthrough
case "ES256":
fallthrough
case "ES384":
fallthrough
case "ES512":
fallthrough
case "EdDSA":
key, err = loadOrCreateAsymmetricKey()
default:
return ErrInvalidAlgorithmType{setting.OAuth2.JWTSigningAlgorithm}
}
if err != nil {
return fmt.Errorf("Error while loading or creating JWT key: %w", err)
}
signingKey, err := CreateJWTSigningKey(setting.OAuth2.JWTSigningAlgorithm, key)
if err != nil {
return err
}
DefaultSigningKey = signingKey
return nil
}
// loadSymmetricKey checks if the configured secret is valid.
// If it is not valid, it will return an error.
func loadSymmetricKey() (interface{}, error) {
key := make([]byte, 32)
n, err := base64.RawURLEncoding.Decode(key, []byte(setting.OAuth2.JWTSecretBase64))
if err != nil {
return nil, err
}
if n != 32 {
return nil, fmt.Errorf("JWT secret must be 32 bytes long")
}
return key, nil
}
// loadOrCreateAsymmetricKey checks if the configured private key exists.
// If it does not exist a new random key gets generated and saved on the configured path.
func loadOrCreateAsymmetricKey() (interface{}, error) {
keyPath := setting.OAuth2.JWTSigningPrivateKeyFile
isExist, err := util.IsExist(keyPath)
if err != nil {
log.Fatal("Unable to check if %s exists. Error: %v", keyPath, err)
}
if !isExist {
err := func() error {
key, err := func() (interface{}, error) {
switch {
case strings.HasPrefix(setting.OAuth2.JWTSigningAlgorithm, "RS"):
return rsa.GenerateKey(rand.Reader, 4096)
case setting.OAuth2.JWTSigningAlgorithm == "EdDSA":
_, pk, err := ed25519.GenerateKey(rand.Reader)
return pk, err
default:
return ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
}
}()
if err != nil {
return err
}
bytes, err := x509.MarshalPKCS8PrivateKey(key)
if err != nil {
return err
}
privateKeyPEM := &pem.Block{Type: "PRIVATE KEY", Bytes: bytes}
if err := os.MkdirAll(filepath.Dir(keyPath), os.ModePerm); err != nil {
return err
}
f, err := os.OpenFile(keyPath, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0o600)
if err != nil {
return err
}
defer func() {
if err = f.Close(); err != nil {
log.Error("Close: %v", err)
}
}()
return pem.Encode(f, privateKeyPEM)
}()
if err != nil {
log.Fatal("Error generating private key: %v", err)
return nil, err
}
}
bytes, err := os.ReadFile(keyPath)
if err != nil {
return nil, err
}
block, _ := pem.Decode(bytes)
if block == nil {
return nil, fmt.Errorf("no valid PEM data found in %s", keyPath)
} else if block.Type != "PRIVATE KEY" {
return nil, fmt.Errorf("expected PRIVATE KEY, got %s in %s", block.Type, keyPath)
}
return x509.ParsePKCS8PrivateKey(block.Bytes)
}