mount: Log params and validate

mount.go

@@ -7,13 +7,15 @@
 package main
 
 import (
+	"fmt"
 	"os"
 	"path/filepath"
 	"strings"
 	"syscall"
 
 	"github.com/kata-containers/agent/pkg/uevent"
 	pb "github.com/kata-containers/agent/protocols/grpc"
+	"github.com/sirupsen/logrus"
 	"golang.org/x/sys/unix"
 	"google.golang.org/grpc/codes"
 	grpcStatus "google.golang.org/grpc/status"
@@ -68,6 +70,32 @@ func createDestinationDir(dest string) error {
 func mount(source, destination, fsType string, flags int, options string) error {
 	var absSource string
 
+	// Log before validation. This is useful to debug cases where the gRPC
+	// protocol version being used by the client is out-of-sync with the
+	// agents version. gRPC message members are strictly ordered, so it's
+	// quite possible that if the protocol changes, the client may
+	// try to pass a valid mountpoint, but the gRPC layer may change that
+	// through the member ordering to be a mount *option* for example.
+	agentLog.WithFields(logrus.Fields{
+		"mount-source":      source,
+		"mount-destination": destination,
+		"mount-fstype":      fsType,
+		"mount-flags":       flags,
+		"mount-options":     options,
+	}).Debug()
+
+	if source == "" {
+		return fmt.Errorf("need mount source")
+	}
+
+	if destination == "" {
+		return fmt.Errorf("need mount destination")
+	}
+
+	if fsType == "" {
+		return fmt.Errorf("need mount FS type")
+	}
+
 	if fsType != type9pFs {
 		var err error
 

mount_test.go

@@ -139,3 +139,34 @@ func TestAddStoragesNoopHandlerFailure(t *testing.T) {
 
 	testAddStoragesFailure(t, storages)
 }
+
+func TestMount(t *testing.T) {
+	assert := assert.New(t)
+
+	type testData struct {
+		source      string
+		destination string
+		fsType      string
+		flags       int
+		options     string
+
+		expectError bool
+	}
+
+	data := []testData{
+		{"", "", "", 0, "", true},
+		{"", "/foo", "9p", 0, "", true},
+		{"proc", "", "9p", 0, "", true},
+		{"proc", "/proc", "", 0, "", true},
+	}
+
+	for i, d := range data {
+		err := mount(d.source, d.destination, d.fsType, d.flags, d.options)
+
+		if d.expectError {
+			assert.Errorf(err, "test %d (%+v)", i, d)
+		} else {
+			assert.NoErrorf(err, "test %d (%+v)", i, d)
+		}
+	}
+}