fix(/commit): protect the commit endpoint via acl (#7608)

/commit endpoint was not ACL protected. In a multi-tenant system, it could be disastrous where a malicious user can commit or abort the transactions of any namespace. This PR partially fixes the issue.

dgraph/cmd/alpha/http.go

@@ -34,13 +34,11 @@ import (
 
 	"github.com/dgraph-io/dgraph/graphql/admin"
 
-	"github.com/dgraph-io/dgo/v200"
 	"github.com/dgraph-io/dgo/v200/protos/api"
 	"github.com/dgraph-io/dgraph/edgraph"
 	"github.com/dgraph-io/dgraph/gql"
 	"github.com/dgraph-io/dgraph/graphql/schema"
 	"github.com/dgraph-io/dgraph/query"
-	"github.com/dgraph-io/dgraph/worker"
 	"github.com/dgraph-io/dgraph/x"
 	"github.com/gogo/protobuf/jsonpb"
 	"github.com/golang/glog"
@@ -471,17 +469,18 @@ func commitHandler(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	ctx := x.AttachAccessJwt(context.Background(), r)
 	var response map[string]interface{}
 	if abort {
-		response, err = handleAbort(startTs)
+		response, err = handleAbort(ctx, startTs)
 	} else {
 		// Keys are sent as an array in the body.
 		reqText := readRequest(w, r)
 		if reqText == nil {
 			return
 		}
 
-		response, err = handleCommit(startTs, reqText)
+		response, err = handleCommit(ctx, startTs, reqText)
 	}
 	if err != nil {
 		x.SetStatus(w, x.ErrorInvalidRequest, err.Error())
@@ -497,27 +496,28 @@ func commitHandler(w http.ResponseWriter, r *http.Request) {
 	_, _ = x.WriteResponse(w, r, js)
 }
 
-func handleAbort(startTs uint64) (map[string]interface{}, error) {
+func handleAbort(ctx context.Context, startTs uint64) (map[string]interface{}, error) {
 	tc := &api.TxnContext{
 		StartTs: startTs,
 		Aborted: true,
 	}
 
-	_, err := worker.CommitOverNetwork(context.Background(), tc)
-	switch err {
-	case dgo.ErrAborted:
+	tctx, err := (&edgraph.Server{}).CommitOrAbort(ctx, tc)
+	switch {
+	case tctx.Aborted:
 		return map[string]interface{}{
 			"code":    x.Success,
 			"message": "Done",
 		}, nil
-	case nil:
+	case err == nil:
 		return nil, errors.Errorf("transaction could not be aborted")
 	default:
 		return nil, err
 	}
 }
 
-func handleCommit(startTs uint64, reqText []byte) (map[string]interface{}, error) {
+func handleCommit(ctx context.Context, startTs uint64, reqText []byte) (map[string]interface{},
+	error) {
 	tc := &api.TxnContext{
 		StartTs: startTs,
 	}
@@ -540,14 +540,13 @@ func handleCommit(startTs uint64, reqText []byte) (map[string]interface{}, error
 		tc.Preds = reqMap["preds"]
 	}
 
-	cts, err := worker.CommitOverNetwork(context.Background(), tc)
+	tc, err := (&edgraph.Server{}).CommitOrAbort(ctx, tc)
 	if err != nil {
 		return nil, err
 	}
 
 	resp := &api.Response{}
 	resp.Txn = tc
-	resp.Txn.CommitTs = cts
 	e := query.Extensions{
 		Txn: resp.Txn,
 	}

edgraph/server.go

@@ -1485,6 +1485,33 @@ func authorizeRequest(ctx context.Context, qc *queryContext) error {
 	return nil
 }
 
+func validateNamespace(ctx context.Context, preds []string) error {
+	ns, err := x.ExtractJWTNamespace(ctx)
+	if err != nil {
+		return err
+	}
+
+	// Do a basic validation that all the predicates passed in transaction context matches the
+	// claimed namespace and user is not accidently commiting a transaction that it did not create.
+	for _, pred := range preds {
+		// Format for Preds in TxnContext is gid-<namespace><pred> (see fillPreds in posting pkg)
+		splits := strings.Split(pred, "-")
+		if len(splits) < 2 {
+			return errors.Errorf("Unable to find group id in %s", pred)
+		}
+		pred = strings.Join(splits[1:], "-")
+		if len(pred) < 8 {
+			return errors.Errorf("found invalid pred %s of length < 8 in transaction context", pred)
+		}
+		if parsedNs := x.ParseNamespace(pred); parsedNs != ns {
+			return errors.Errorf("Please login into correct namespace. "+
+				"Currently logged in namespace %#x", ns)
+		}
+	}
+
+	return nil
+}
+
 // CommitOrAbort commits or aborts a transaction.
 func (s *Server) CommitOrAbort(ctx context.Context, tc *api.TxnContext) (*api.TxnContext, error) {
 	ctx, span := otrace.StartSpan(ctx, "Server.CommitOrAbort")
@@ -1494,6 +1521,12 @@ func (s *Server) CommitOrAbort(ctx context.Context, tc *api.TxnContext) (*api.Tx
 		return &api.TxnContext{}, err
 	}
 
+	if x.WorkerConfig.AclEnabled {
+		if err := validateNamespace(ctx, tc.Preds); err != nil {
+			return &api.TxnContext{}, err
+		}
+	}
+
 	tctx := &api.TxnContext{}
 	if tc.StartTs == 0 {
 		return &api.TxnContext{}, errors.Errorf(
@@ -1506,11 +1539,11 @@ func (s *Server) CommitOrAbort(ctx context.Context, tc *api.TxnContext) (*api.Tx
 	if err == dgo.ErrAborted {
 		// If err returned is dgo.ErrAborted and tc.Aborted was set, that means the client has
 		// aborted the transaction by calling txn.Discard(). Hence return a nil error.
+		tctx.Aborted = true
 		if tc.Aborted {
 			return tctx, nil
 		}
 
-		tctx.Aborted = true
 		return tctx, status.Errorf(codes.Aborted, err.Error())
 	}
 	tctx.StartTs = tc.StartTs