Use Gitaly's v2 auth schemegitaly-auth-v2

2 files changed, 150 insertions, 0 deletions

diff --git a/go/vendor/gitlab.com/gitlab-org/gitaly/auth/rpccredentials.go b/go/vendor/gitlab.com/gitlab-org/gitaly/auth/rpccredentials.go
index cbe94c2..c35cd4d 100644
--- a/go/vendor/gitlab.com/gitlab-org/gitaly/auth/rpccredentials.go
+++ b/go/vendor/gitlab.com/gitlab-org/gitaly/auth/rpccredentials.go
@@ -2,6 +2,9 @@ package gitalyauth
 
 import (
 	"encoding/base64"
+	"fmt"
+	"strconv"
+	"time"
 
 	"golang.org/x/net/context"
 	"google.golang.org/grpc/credentials"
@@ -23,3 +26,31 @@ func (*rpcCredentials) RequireTransportSecurity() bool { return false }
 func (rc *rpcCredentials) GetRequestMetadata(context.Context, ...string) (map[string]string, error) {
 	return map[string]string{"authorization": "Bearer " + rc.token}, nil
 }
+
+// RPCCredentialsV2 can be used with grpc.WithPerRPCCredentials to create a
+// grpc.DialOption that inserts an HMAC token with the current timestamp
+// for authentication with a Gitaly server.
+func RPCCredentialsV2(token string) credentials.PerRPCCredentials {
+	return &rpcCredentialsV2{token: token}
+}
+
+type rpcCredentialsV2 struct {
+	token string
+}
+
+func (*rpcCredentialsV2) RequireTransportSecurity() bool { return false }
+
+func (rc *rpcCredentialsV2) GetRequestMetadata(context.Context, ...string) (map[string]string, error) {
+	return map[string]string{"authorization": "Bearer " + rc.hmacToken()}, nil
+}
+
+func (rc *rpcCredentialsV2) hmacToken() string {
+	return hmacToken("v2", []byte(rc.token), time.Now())
+}
+
+func hmacToken(version string, secret []byte, timestamp time.Time) string {
+	intTime := timestamp.Unix()
+	signedTimestamp := hmacSign(secret, strconv.FormatInt(intTime, 10))
+
+	return fmt.Sprintf("%s.%x.%d", version, signedTimestamp, intTime)
+}
diff --git a/go/vendor/gitlab.com/gitlab-org/gitaly/auth/token.go b/go/vendor/gitlab.com/gitlab-org/gitaly/auth/token.go
new file mode 100644
index 0000000..e1c1966
--- /dev/null
+++ b/go/vendor/gitlab.com/gitlab-org/gitaly/auth/token.go
@@ -0,0 +1,119 @@
+package gitalyauth
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"crypto/subtle"
+	"encoding/base64"
+	"encoding/hex"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/grpc-ecosystem/go-grpc-middleware/auth"
+	"golang.org/x/net/context"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+)
+
+const (
+	timestampThreshold = 30 * time.Second
+)
+
+var (
+	errUnauthenticated = status.Errorf(codes.Unauthenticated, "authentication required")
+	errDenied          = status.Errorf(codes.PermissionDenied, "permission denied")
+)
+
+// AuthInfo contains the authentication information coming from a request
+type AuthInfo struct {
+	Version       string
+	SignedMessage []byte
+	Message       string
+}
+
+// CheckToken checks the 'authentication' header of incoming gRPC
+// metadata in ctx. It returns nil if and only if the token matches
+// secret.
+func CheckToken(ctx context.Context, secret string, targetTime time.Time) error {
+	if len(secret) == 0 {
+		panic("CheckToken: secret may not be empty")
+	}
+
+	authInfo, err := ExtractAuthInfo(ctx)
+	if err != nil {
+		return errUnauthenticated
+	}
+
+	switch authInfo.Version {
+	case "v1":
+		decodedToken, err := base64.StdEncoding.DecodeString(authInfo.Message)
+		if err != nil {
+			return errUnauthenticated
+		}
+
+		if tokensEqual(decodedToken, []byte(secret)) {
+			return nil
+		}
+	case "v2":
+		if hmacInfoValid(authInfo.Message, authInfo.SignedMessage, []byte(secret), targetTime, timestampThreshold) {
+			return nil
+		}
+	}
+
+	return errDenied
+}
+
+func tokensEqual(tok1, tok2 []byte) bool {
+	return subtle.ConstantTimeCompare(tok1, tok2) == 1
+}
+
+// ExtractAuthInfo returns an `AuthInfo` with the data extracted from `ctx`
+func ExtractAuthInfo(ctx context.Context) (*AuthInfo, error) {
+	token, err := grpc_auth.AuthFromMD(ctx, "bearer")
+
+	if err != nil {
+		return nil, err
+	}
+
+	split := strings.SplitN(string(token), ".", 3)
+
+	// v1 is base64-encoded using base64.StdEncoding, which cannot contain a ".".
+	// A v1 token cannot slip through here.
+	if len(split) != 3 {
+		return &AuthInfo{Version: "v1", Message: token}, nil
+	}
+
+	version, sig, msg := split[0], split[1], split[2]
+	decodedSig, err := hex.DecodeString(sig)
+	if err != nil {
+		return nil, err
+	}
+
+	return &AuthInfo{Version: version, SignedMessage: decodedSig, Message: msg}, nil
+}
+
+func hmacInfoValid(message string, signedMessage, secret []byte, targetTime time.Time, timestampThreshold time.Duration) bool {
+	expectedHMAC := hmacSign(secret, message)
+	if !hmac.Equal(signedMessage, expectedHMAC) {
+		return false
+	}
+
+	timestamp, err := strconv.ParseInt(message, 10, 64)
+	if err != nil {
+		return false
+	}
+
+	issuedAt := time.Unix(timestamp, 0)
+	lowerBound := targetTime.Add(-timestampThreshold)
+	upperBound := targetTime.Add(timestampThreshold)
+
+	return issuedAt.After(lowerBound) && issuedAt.Before(upperBound)
+}
+
+func hmacSign(secret []byte, message string) []byte {
+	mac := hmac.New(sha256.New, secret)
+	mac.Write([]byte(message))
+
+	return mac.Sum(nil)
+}