Support some PTY control characters

pkg/sentry/fsimpl/devpts/line_discipline.go

@@ -111,6 +111,10 @@ type lineDiscipline struct {
 
 	// replicaWaiter is used to wait on the replica end of the TTY.
 	replicaWaiter waiter.Queue
+
+	// fgProcessGroup is the foreground process group that is currently
+	// connected to this TTY.
+	fgProcessGroup *kernel.ProcessGroup
 }
 
 func newLineDiscipline(termios linux.KernelTermios) *lineDiscipline {
@@ -120,6 +124,10 @@ func newLineDiscipline(termios linux.KernelTermios) *lineDiscipline {
 	return &ld
 }
 
+func (l *lineDiscipline) SetForegroundProcessGroup(pg *kernel.ProcessGroup) {
+	l.fgProcessGroup = pg
+}
+
 // getTermios gets the linux.Termios for the tty.
 func (l *lineDiscipline) getTermios(task *kernel.Task, args arch.SyscallArguments) (uintptr, error) {
 	l.termiosMu.RLock()
@@ -393,6 +401,10 @@ func (*inputQueueTransformer) transform(l *lineDiscipline, q *queue, buf []byte)
 			if l.termios.IEnabled(linux.INLCR) {
 				cBytes[0] = '\r'
 			}
+		case l.termios.ControlCharacters[linux.VINTR]: // ctrl-c
+			l.fgProcessGroup.SendSignal(kernel.SignalInfoPriv(linux.SIGINT))
+		case l.termios.ControlCharacters[linux.VSUSP]: // ctrl-z
+			l.fgProcessGroup.SendSignal(kernel.SignalInfoPriv(linux.SIGTSTP))
 		}
 
 		// In canonical mode, we discard non-terminating characters

pkg/sentry/fsimpl/devpts/terminal.go

@@ -105,6 +105,9 @@ func (tm *Terminal) setForegroundProcessGroup(ctx context.Context, args arch.Sys
 		return 0, err
 	}
 
+	// Put the processgroup also in line discipline for further signal handling
+	tm.ld.SetForegroundProcessGroup(task.ThreadGroup().ProcessGroup())
+
 	ret, err := task.ThreadGroup().SetForegroundProcessGroup(tm.tty(isMaster), kernel.ProcessGroupID(pgid))
 	return uintptr(ret), err
 }