4 files changed, 42 insertions, 0 deletions
diff --git a/pkg/abi/linux/tty.go b/pkg/abi/linux/tty.go
index 81156867c..f63dc52aa 100644
--- a/pkg/abi/linux/tty.go
+++ b/pkg/abi/linux/tty.go
@@ -328,3 +328,13 @@ var DefaultSlaveTermios = KernelTermios{
 	InputSpeed:        38400,
 	OutputSpeed:       38400,
 }
+
+// WindowSize corresponds to struct winsize defined in
+// include/uapi/asm-generic/termios.h.
+//
+// +stateify savable
+type WindowSize struct {
+	Rows uint16
+	Cols uint16
+	_    [4]byte // Padding for 2 unused shorts.
+}
diff --git a/pkg/sentry/fs/tty/line_discipline.go b/pkg/sentry/fs/tty/line_discipline.go
index c7f6c5645..31804571e 100644
--- a/pkg/sentry/fs/tty/line_discipline.go
+++ b/pkg/sentry/fs/tty/line_discipline.go
@@ -76,6 +76,12 @@ const (
 //
 // +stateify savable
 type lineDiscipline struct {
+	// sizeMu protects size.
+	sizeMu sync.Mutex `state:"nosave"`
+
+	// size is the terminal size (width and height).
+	size linux.WindowSize
+
 	// inQueue is the input queue of the terminal.
 	inQueue queue
 
@@ -142,6 +148,24 @@ func (l *lineDiscipline) setTermios(ctx context.Context, io usermem.IO, args arc
 	return 0, err
 }
 
+func (l *lineDiscipline) windowSize(ctx context.Context, io usermem.IO, args arch.SyscallArguments) error {
+	l.sizeMu.Lock()
+	defer l.sizeMu.Unlock()
+	_, err := usermem.CopyObjectOut(ctx, io, args[2].Pointer(), l.size, usermem.IOOpts{
+		AddressSpaceActive: true,
+	})
+	return err
+}
+
+func (l *lineDiscipline) setWindowSize(ctx context.Context, io usermem.IO, args arch.SyscallArguments) error {
+	l.sizeMu.Lock()
+	defer l.sizeMu.Unlock()
+	_, err := usermem.CopyObjectIn(ctx, io, args[2].Pointer(), &l.size, usermem.IOOpts{
+		AddressSpaceActive: true,
+	})
+	return err
+}
+
 func (l *lineDiscipline) masterReadiness() waiter.EventMask {
 	// We don't have to lock a termios because the default master termios
 	// is immutable.
diff --git a/pkg/sentry/fs/tty/master.go b/pkg/sentry/fs/tty/master.go
index c8dc08c1a..ae7540eff 100644
--- a/pkg/sentry/fs/tty/master.go
+++ b/pkg/sentry/fs/tty/master.go
@@ -172,6 +172,10 @@ func (mf *masterFileOperations) Ioctl(ctx context.Context, io usermem.IO, args a
 	case linux.TIOCSPTLCK:
 		// TODO: Implement pty locking. For now just pretend we do.
 		return 0, nil
+	case linux.TIOCGWINSZ:
+		return 0, mf.t.ld.windowSize(ctx, io, args)
+	case linux.TIOCSWINSZ:
+		return 0, mf.t.ld.setWindowSize(ctx, io, args)
 	default:
 		return 0, syserror.ENOTTY
 	}
diff --git a/pkg/sentry/fs/tty/slave.go b/pkg/sentry/fs/tty/slave.go
index ab92ced7e..963331b9b 100644
--- a/pkg/sentry/fs/tty/slave.go
+++ b/pkg/sentry/fs/tty/slave.go
@@ -150,6 +150,10 @@ func (sf *slaveFileOperations) Ioctl(ctx context.Context, io usermem.IO, args ar
 			AddressSpaceActive: true,
 		})
 		return 0, err
+	case linux.TIOCGWINSZ:
+		return 0, sf.si.t.ld.windowSize(ctx, io, args)
+	case linux.TIOCSWINSZ:
+		return 0, sf.si.t.ld.setWindowSize(ctx, io, args)
 	default:
 		return 0, syserror.ENOTTY
 	}