mirror of
https://github.com/go-gitea/gitea.git
synced 2024-08-22 20:33:46 +02:00
208 lines
5.9 KiB
Go
Vendored
208 lines
5.9 KiB
Go
Vendored
// @author Couchbase <info@couchbase.com>
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// @copyright 2018 Couchbase, Inc.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// Package scramsha provides implementation of client side SCRAM-SHA
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// according to https://tools.ietf.org/html/rfc5802
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package scramsha
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import (
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"crypto/hmac"
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"crypto/rand"
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"crypto/sha1"
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"crypto/sha256"
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"crypto/sha512"
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"encoding/base64"
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"fmt"
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"github.com/pkg/errors"
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"golang.org/x/crypto/pbkdf2"
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"hash"
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"strconv"
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"strings"
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)
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func hmacHash(message []byte, secret []byte, hashFunc func() hash.Hash) []byte {
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h := hmac.New(hashFunc, secret)
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h.Write(message)
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return h.Sum(nil)
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}
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func shaHash(message []byte, hashFunc func() hash.Hash) []byte {
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h := hashFunc()
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h.Write(message)
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return h.Sum(nil)
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}
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func generateClientNonce(size int) (string, error) {
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randomBytes := make([]byte, size)
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_, err := rand.Read(randomBytes)
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if err != nil {
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return "", errors.Wrap(err, "Unable to generate nonce")
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}
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return base64.StdEncoding.EncodeToString(randomBytes), nil
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}
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// ScramSha provides context for SCRAM-SHA handling
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type ScramSha struct {
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hashSize int
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hashFunc func() hash.Hash
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clientNonce string
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serverNonce string
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salt []byte
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i int
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saltedPassword []byte
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authMessage string
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}
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var knownMethods = []string{"SCRAM-SHA512", "SCRAM-SHA256", "SCRAM-SHA1"}
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// BestMethod returns SCRAM-SHA method we consider the best out of suggested
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// by server
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func BestMethod(methods string) (string, error) {
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for _, m := range knownMethods {
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if strings.Index(methods, m) != -1 {
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return m, nil
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}
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}
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return "", errors.Errorf(
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"None of the server suggested methods [%s] are supported",
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methods)
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}
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// NewScramSha creates context for SCRAM-SHA handling
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func NewScramSha(method string) (*ScramSha, error) {
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s := &ScramSha{}
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if method == knownMethods[0] {
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s.hashFunc = sha512.New
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s.hashSize = 64
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} else if method == knownMethods[1] {
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s.hashFunc = sha256.New
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s.hashSize = 32
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} else if method == knownMethods[2] {
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s.hashFunc = sha1.New
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s.hashSize = 20
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} else {
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return nil, errors.Errorf("Unsupported method %s", method)
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}
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return s, nil
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}
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// GetStartRequest builds start SCRAM-SHA request to be sent to server
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func (s *ScramSha) GetStartRequest(user string) (string, error) {
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var err error
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s.clientNonce, err = generateClientNonce(24)
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if err != nil {
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return "", errors.Wrapf(err, "Unable to generate SCRAM-SHA "+
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"start request for user %s", user)
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}
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message := fmt.Sprintf("n,,n=%s,r=%s", user, s.clientNonce)
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s.authMessage = message[3:]
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return message, nil
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}
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// HandleStartResponse handles server response on start SCRAM-SHA request
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func (s *ScramSha) HandleStartResponse(response string) error {
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parts := strings.Split(response, ",")
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if len(parts) != 3 {
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return errors.Errorf("expected 3 fields in first SCRAM-SHA-1 "+
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"server message %s", response)
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}
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if !strings.HasPrefix(parts[0], "r=") || len(parts[0]) < 3 {
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return errors.Errorf("Server sent an invalid nonce %s",
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parts[0])
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}
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if !strings.HasPrefix(parts[1], "s=") || len(parts[1]) < 3 {
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return errors.Errorf("Server sent an invalid salt %s", parts[1])
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}
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if !strings.HasPrefix(parts[2], "i=") || len(parts[2]) < 3 {
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return errors.Errorf("Server sent an invalid iteration count %s",
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parts[2])
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}
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s.serverNonce = parts[0][2:]
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encodedSalt := parts[1][2:]
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var err error
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s.i, err = strconv.Atoi(parts[2][2:])
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if err != nil {
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return errors.Errorf("Iteration count %s must be integer.",
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parts[2][2:])
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}
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if s.i < 1 {
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return errors.New("Iteration count should be positive")
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}
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if !strings.HasPrefix(s.serverNonce, s.clientNonce) {
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return errors.Errorf("Server nonce %s doesn't contain client"+
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" nonce %s", s.serverNonce, s.clientNonce)
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}
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s.salt, err = base64.StdEncoding.DecodeString(encodedSalt)
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if err != nil {
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return errors.Wrapf(err, "Unable to decode salt %s",
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encodedSalt)
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}
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s.authMessage = s.authMessage + "," + response
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return nil
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}
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// GetFinalRequest builds final SCRAM-SHA request to be sent to server
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func (s *ScramSha) GetFinalRequest(pass string) string {
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clientFinalMessageBare := "c=biws,r=" + s.serverNonce
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s.authMessage = s.authMessage + "," + clientFinalMessageBare
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s.saltedPassword = pbkdf2.Key([]byte(pass), s.salt, s.i,
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s.hashSize, s.hashFunc)
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clientKey := hmacHash([]byte("Client Key"), s.saltedPassword, s.hashFunc)
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storedKey := shaHash(clientKey, s.hashFunc)
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clientSignature := hmacHash([]byte(s.authMessage), storedKey, s.hashFunc)
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clientProof := make([]byte, len(clientSignature))
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for i := 0; i < len(clientSignature); i++ {
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clientProof[i] = clientKey[i] ^ clientSignature[i]
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}
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return clientFinalMessageBare + ",p=" +
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base64.StdEncoding.EncodeToString(clientProof)
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}
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// HandleFinalResponse handles server's response on final SCRAM-SHA request
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func (s *ScramSha) HandleFinalResponse(response string) error {
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if strings.Contains(response, ",") ||
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!strings.HasPrefix(response, "v=") {
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return errors.Errorf("Server sent an invalid final message %s",
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response)
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}
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decodedMessage, err := base64.StdEncoding.DecodeString(response[2:])
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if err != nil {
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return errors.Wrapf(err, "Unable to decode server message %s",
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response[2:])
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}
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serverKey := hmacHash([]byte("Server Key"), s.saltedPassword,
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s.hashFunc)
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serverSignature := hmacHash([]byte(s.authMessage), serverKey,
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s.hashFunc)
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if string(decodedMessage) != string(serverSignature) {
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return errors.Errorf("Server proof %s doesn't match "+
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"the expected: %s",
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string(decodedMessage), string(serverSignature))
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}
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return nil
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}
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