s390/3270: hangup the 3270 tty after a disconnect

The disconnect and later reconnect of a 3270 terminal does not do
a tty hangup. The current session is resumed which is a security
issue.

Do a tty hangup after a unit check has been received.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

1 files changed, 35 insertions, 3 deletions

diff --git a/drivers/s390/char/tty3270.c b/drivers/s390/char/tty3270.c
index 402eff3c1634..0a9f219fdc7c 100644
--- a/drivers/s390/char/tty3270.c
+++ b/drivers/s390/char/tty3270.c
@@ -92,6 +92,7 @@ struct tty3270 {
         unsigned char inattr;           /* Visible/invisible input. */
         int throttle, attn;             /* tty throttle/unthrottle. */
         struct tasklet_struct readlet;  /* Tasklet to issue read request. */
+        struct tasklet_struct hanglet;  /* Tasklet to hang up the tty. */
         struct kbd_data *kbd;           /* key_maps stuff. */
 
         /* Escape sequence parsing. */
@@ -646,6 +647,16 @@ tty3270_issue_read(struct tty3270 *tp, int lock)
 }
 
 /*
+ * Hang up the tty
+ */
+static void
+tty3270_hangup_tasklet(struct tty3270 *tp)
+{
+        tty_port_tty_hangup(&tp->port, true);
+        raw3270_put_view(&tp->view);
+}
+
+/*
  * Switch to the tty view.
  */
 static int
@@ -678,11 +689,14 @@ tty3270_irq(struct tty3270 *tp, struct raw3270_request *rq, struct irb *irb)
         }
 
         if (rq) {
-                if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK)
+                if (irb->scsw.cmd.dstat & DEV_STAT_UNIT_CHECK) {
                         rq->rc = -EIO;
-                else
+                        raw3270_get_view(&tp->view);
+                        tasklet_schedule(&tp->hanglet);
+                } else {
                         /* Normal end. Copy residual count. */
                         rq->rescnt = irb->scsw.cmd.count;
+                }
         } else if (irb->scsw.cmd.dstat & DEV_STAT_DEV_END) {
                 /* Interrupt without an outstanding request -> update all */
                 tp->update_flags = TTY_UPDATE_ALL;
@@ -739,6 +753,9 @@ tty3270_alloc_view(void)
         tasklet_init(&tp->readlet,
                      (void (*)(unsigned long)) tty3270_read_tasklet,
                      (unsigned long) tp->read);
+        tasklet_init(&tp->hanglet,
+                     (void (*)(unsigned long)) tty3270_hangup_tasklet,
+                     (unsigned long) tp);
         INIT_WORK(&tp->resize_work, tty3270_resize_work);
 
         return tp;
@@ -1812,7 +1829,22 @@ tty3270_unthrottle(struct tty_struct * tty)
 static void
 tty3270_hangup(struct tty_struct *tty)
 {
-        // FIXME: implement
+        struct tty3270 *tp;
+
+        tp = tty->driver_data;
+        if (!tp)
+                return;
+        spin_lock_bh(&tp->view.lock);
+        tp->cx = tp->saved_cx = 0;
+        tp->cy = tp->saved_cy = 0;
+        tp->highlight = tp->saved_highlight = TAX_RESET;
+        tp->f_color = tp->saved_f_color = TAC_RESET;
+        tty3270_blank_screen(tp);
+        while (tp->nr_lines < tp->view.rows - 2)
+                tty3270_blank_line(tp);
+        tp->update_flags = TTY_UPDATE_ALL;
+        spin_unlock_bh(&tp->view.lock);
+        tty3270_set_timer(tp, 1);
 }
 
 static void