1 files changed, 21 insertions, 5 deletions
diff --git a/pkg/sentry/kernel/kernel.go b/pkg/sentry/kernel/kernel.go
index cf8bf3ecd..55a9d3d29 100644
--- a/pkg/sentry/kernel/kernel.go
+++ b/pkg/sentry/kernel/kernel.go
@@ -590,11 +590,17 @@ func (k *Kernel) UniqueID() uint64 {
 
 // CreateProcessArgs holds arguments to kernel.CreateProcess.
 type CreateProcessArgs struct {
-	// Filename is the filename to load.
+	// Filename is the filename to load as the init binary.
 	//
-	// If this is provided as "", then the file will be guessed via Argv[0].
+	// If this is provided as "", File will be checked, then the file will be
+	// guessed via Argv[0].
 	Filename string
 
+	// File is a passed host FD pointing to a file to load as the init binary.
+	//
+	// This is checked if and only if Filename is "".
+	File *fs.File
+
 	// Argvv is a list of arguments.
 	Argv []string
 
@@ -779,8 +785,16 @@ func (k *Kernel) CreateProcess(args CreateProcessArgs) (*ThreadGroup, ThreadID,
 		defer wd.DecRef()
 	}
 
-	if args.Filename == "" {
-		// Was anything provided?
+	// Check which file to start from.
+	switch {
+	case args.Filename != "":
+		// If a filename is given, take that.
+		// Set File to nil so we resolve the path in LoadTaskImage.
+		args.File = nil
+	case args.File != nil:
+		// If File is set, take the File provided directly.
+	default:
+		// Otherwise look at Argv and see if the first argument is a valid path.
 		if len(args.Argv) == 0 {
 			return nil, 0, fmt.Errorf("no filename or command provided")
 		}
@@ -792,7 +806,9 @@ func (k *Kernel) CreateProcess(args CreateProcessArgs) (*ThreadGroup, ThreadID,
 
 	// Create a fresh task context.
 	remainingTraversals = uint(args.MaxSymlinkTraversals)
-	tc, se := k.LoadTaskImage(ctx, k.mounts, root, wd, &remainingTraversals, args.Filename, args.Argv, args.Envv, k.featureSet)
+
+	tc, se := k.LoadTaskImage(ctx, k.mounts, root, wd, &remainingTraversals, args.Filename, args.File, args.Argv, args.Envv, k.featureSet)
+
 	if se != nil {
 		return nil, 0, errors.New(se.String())
 	}