vt: Add virtual console keyboard mode OFF

virtual console: add keyboard mode OFF

Add a new mode for the virtual console keyboard OFF in which all input
other than shift keys is ignored. Prevents vt input buffers from
overflowing when a program opens but doesn't read from a tty, like X11
using evdev for input.

Signed-off-by: Arthur Taylor <art@ified.ca>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 6 insertions, 2 deletions

diff --git a/drivers/tty/vt/keyboard.c b/drivers/tty/vt/keyboard.c
index e95d7876ca6b..6dd3c68c13ad 100644
--- a/drivers/tty/vt/keyboard.c
+++ b/drivers/tty/vt/keyboard.c
@@ -654,7 +654,8 @@ static void k_spec(struct vc_data *vc, unsigned char value, char up_flag)
         if (value >= ARRAY_SIZE(fn_handler))
                 return;
         if ((kbd->kbdmode == VC_RAW ||
-             kbd->kbdmode == VC_MEDIUMRAW) &&
+             kbd->kbdmode == VC_MEDIUMRAW ||
+             kbd->kbdmode == VC_OFF) &&
              value != KVAL(K_SAK))
                 return;         /* SAK is allowed even in raw mode */
         fn_handler[value](vc);
@@ -1295,7 +1296,7 @@ static void kbd_keycode(unsigned int keycode, int down, int hw_raw)
         if (rc == NOTIFY_STOP)
                 return;
 
-        if (raw_mode && type != KT_SPEC && type != KT_SHIFT)
+        if ((raw_mode || kbd->kbdmode == VC_OFF) && type != KT_SPEC && type != KT_SHIFT)
                 return;
 
         (*k_handler[type])(vc, keysym & 0xff, !down);
diff --git a/drivers/tty/vt/vt_ioctl.c b/drivers/tty/vt/vt_ioctl.c
index 1235ebda6e1c..6bcf05bf4978 100644
--- a/drivers/tty/vt/vt_ioctl.c
+++ b/drivers/tty/vt/vt_ioctl.c
@@ -688,6 +688,9 @@ int vt_ioctl(struct tty_struct *tty, struct file * file,
                         kbd->kbdmode = VC_UNICODE;
                         compute_shiftstate();
                         break;
+                  case K_OFF:
+                        kbd->kbdmode = VC_OFF;
+                        break;
                   default:
                         ret = -EINVAL;
                         goto out;