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* [PATCH v2] Bluetooth: hci_uart: Switch pty driver to slave side in tty_set_termios()
@ 2019-02-02  7:28 Myungho Jung
  2019-02-02 12:15 ` Marcel Holtmann
  0 siblings, 1 reply; 3+ messages in thread
From: Myungho Jung @ 2019-02-02  7:28 UTC (permalink / raw)
  To: Marcel Holtmann, Johan Hedberg; +Cc: linux-bluetooth, linux-kernel

tty_set_termios() should be called with slave side of pty driver. So, If
tty driver is pty master, it needs to be switched to ->link.

Reported-by: syzbot+a950165cbb86bdd023a4@syzkaller.appspotmail.com
Signed-off-by: Myungho Jung <mhjungk@gmail.com>
---
 drivers/bluetooth/hci_ldisc.c | 27 ++++++++++++++++++++++-----
 1 file changed, 22 insertions(+), 5 deletions(-)

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index fbf7b4df23ab..0f6e70ea1dc3 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -299,10 +299,21 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
 	return 0;
 }
 
+/* If pty master, return slave side */
+static struct tty_struct *hci_uart_get_real_tty(struct tty_struct *tty)
+{
+	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
+	    tty->driver->subtype == PTY_TYPE_MASTER)
+		tty->link;
+
+	return tty;
+}
+
 /* Flow control or un-flow control the device */
 void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
 {
 	struct tty_struct *tty = hu->tty;
+	struct tty_struct *real_tty;
 	struct ktermios ktermios;
 	int status;
 	unsigned int set = 0;
@@ -314,11 +325,14 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
 		return;
 	}
 
+	/* termios should be set from slave side if tty driver is pty */
+	real_tty = hci_uart_get_real_tty(tty);
+
 	if (enable) {
 		/* Disable hardware flow control */
-		ktermios = tty->termios;
+		ktermios = real_tty->termios;
 		ktermios.c_cflag &= ~CRTSCTS;
-		status = tty_set_termios(tty, &ktermios);
+		status = tty_set_termios(real_tty, &ktermios);
 		BT_DBG("Disabling hardware flow control: %s",
 		       status ? "failed" : "success");
 
@@ -350,9 +364,9 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
 		BT_DBG("Setting RTS: %s", status ? "failed" : "success");
 
 		/* Re-enable hardware flow control */
-		ktermios = tty->termios;
+		ktermios = real_tty->termios;
 		ktermios.c_cflag |= CRTSCTS;
-		status = tty_set_termios(tty, &ktermios);
+		status = tty_set_termios(real_tty, &ktermios);
 		BT_DBG("Enabling hardware flow control: %s",
 		       status ? "failed" : "success");
 	}
@@ -367,9 +381,12 @@ void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed,
 
 void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed)
 {
-	struct tty_struct *tty = hu->tty;
+	struct tty_struct *tty;
 	struct ktermios ktermios;
 
+	/* termios should be set from slave side if tty driver is pty */
+	tty = hci_uart_get_real_tty(hu->tty);
+
 	ktermios = tty->termios;
 	ktermios.c_cflag &= ~CBAUD;
 	tty_termios_encode_baud_rate(&ktermios, speed, speed);
-- 
2.17.1


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH v2] Bluetooth: hci_uart: Switch pty driver to slave side in tty_set_termios()
  2019-02-02  7:28 [PATCH v2] Bluetooth: hci_uart: Switch pty driver to slave side in tty_set_termios() Myungho Jung
@ 2019-02-02 12:15 ` Marcel Holtmann
  2019-02-03  3:30   ` Myungho Jung
  0 siblings, 1 reply; 3+ messages in thread
From: Marcel Holtmann @ 2019-02-02 12:15 UTC (permalink / raw)
  To: Myungho Jung; +Cc: Johan Hedberg, linux-bluetooth, linux-kernel

Hi Myungho,

> tty_set_termios() should be called with slave side of pty driver. So, If
> tty driver is pty master, it needs to be switched to ->link.
> 
> Reported-by: syzbot+a950165cbb86bdd023a4@syzkaller.appspotmail.com
> Signed-off-by: Myungho Jung <mhjungk@gmail.com>
> ---
> drivers/bluetooth/hci_ldisc.c | 27 ++++++++++++++++++++++-----
> 1 file changed, 22 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
> index fbf7b4df23ab..0f6e70ea1dc3 100644
> --- a/drivers/bluetooth/hci_ldisc.c
> +++ b/drivers/bluetooth/hci_ldisc.c
> @@ -299,10 +299,21 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
> 	return 0;
> }
> 
> +/* If pty master, return slave side */
> +static struct tty_struct *hci_uart_get_real_tty(struct tty_struct *tty)
> +{
> +	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
> +	    tty->driver->subtype == PTY_TYPE_MASTER)
> +		tty->link;
> +
> +	return tty;
> +}
> +
> /* Flow control or un-flow control the device */
> void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
> {
> 	struct tty_struct *tty = hu->tty;
> +	struct tty_struct *real_tty;
> 	struct ktermios ktermios;
> 	int status;
> 	unsigned int set = 0;
> @@ -314,11 +325,14 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
> 		return;
> 	}
> 
> +	/* termios should be set from slave side if tty driver is pty */
> +	real_tty = hci_uart_get_real_tty(tty);
> +
> 	if (enable) {
> 		/* Disable hardware flow control */
> -		ktermios = tty->termios;
> +		ktermios = real_tty->termios;
> 		ktermios.c_cflag &= ~CRTSCTS;
> -		status = tty_set_termios(tty, &ktermios);
> +		status = tty_set_termios(real_tty, &ktermios);
> 		BT_DBG("Disabling hardware flow control: %s",
> 		       status ? "failed" : "success");
> 
> @@ -350,9 +364,9 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
> 		BT_DBG("Setting RTS: %s", status ? "failed" : "success");
> 
> 		/* Re-enable hardware flow control */
> -		ktermios = tty->termios;
> +		ktermios = real_tty->termios;
> 		ktermios.c_cflag |= CRTSCTS;
> -		status = tty_set_termios(tty, &ktermios);
> +		status = tty_set_termios(real_tty, &ktermios);
> 		BT_DBG("Enabling hardware flow control: %s",
> 		       status ? "failed" : "success");
> 	}
> @@ -367,9 +381,12 @@ void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed,
> 
> void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed)
> {
> -	struct tty_struct *tty = hu->tty;
> +	struct tty_struct *tty;
> 	struct ktermios ktermios;
> 
> +	/* termios should be set from slave side if tty driver is pty */
> +	tty = hci_uart_get_real_tty(hu->tty);
> +

didn’t we conclude that allowing the HCI line discipline on a PTY master isn't worth the effort? The ptm_unix98_ops doesn’t have the .set_termios and thus, just check that ops->set_termios is present in hci_uart_tty_open and if not fail with EOPNOTSUPP like we do for missing ops->write.

Regards

Marcel


^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [PATCH v2] Bluetooth: hci_uart: Switch pty driver to slave side in tty_set_termios()
  2019-02-02 12:15 ` Marcel Holtmann
@ 2019-02-03  3:30   ` Myungho Jung
  0 siblings, 0 replies; 3+ messages in thread
From: Myungho Jung @ 2019-02-03  3:30 UTC (permalink / raw)
  To: Marcel Holtmann; +Cc: Johan Hedberg, linux-bluetooth, linux-kernel

On Sat, Feb 02, 2019 at 01:15:16PM +0100, Marcel Holtmann wrote:
> Hi Myungho,
> 
> > tty_set_termios() should be called with slave side of pty driver. So, If
> > tty driver is pty master, it needs to be switched to ->link.
> > 
> > Reported-by: syzbot+a950165cbb86bdd023a4@syzkaller.appspotmail.com
> > Signed-off-by: Myungho Jung <mhjungk@gmail.com>
> > ---
> > drivers/bluetooth/hci_ldisc.c | 27 ++++++++++++++++++++++-----
> > 1 file changed, 22 insertions(+), 5 deletions(-)
> > 
> > diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
> > index fbf7b4df23ab..0f6e70ea1dc3 100644
> > --- a/drivers/bluetooth/hci_ldisc.c
> > +++ b/drivers/bluetooth/hci_ldisc.c
> > @@ -299,10 +299,21 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
> > 	return 0;
> > }
> > 
> > +/* If pty master, return slave side */
> > +static struct tty_struct *hci_uart_get_real_tty(struct tty_struct *tty)
> > +{
> > +	if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
> > +	    tty->driver->subtype == PTY_TYPE_MASTER)
> > +		tty->link;
> > +
> > +	return tty;
> > +}
> > +
> > /* Flow control or un-flow control the device */
> > void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
> > {
> > 	struct tty_struct *tty = hu->tty;
> > +	struct tty_struct *real_tty;
> > 	struct ktermios ktermios;
> > 	int status;
> > 	unsigned int set = 0;
> > @@ -314,11 +325,14 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
> > 		return;
> > 	}
> > 
> > +	/* termios should be set from slave side if tty driver is pty */
> > +	real_tty = hci_uart_get_real_tty(tty);
> > +
> > 	if (enable) {
> > 		/* Disable hardware flow control */
> > -		ktermios = tty->termios;
> > +		ktermios = real_tty->termios;
> > 		ktermios.c_cflag &= ~CRTSCTS;
> > -		status = tty_set_termios(tty, &ktermios);
> > +		status = tty_set_termios(real_tty, &ktermios);
> > 		BT_DBG("Disabling hardware flow control: %s",
> > 		       status ? "failed" : "success");
> > 
> > @@ -350,9 +364,9 @@ void hci_uart_set_flow_control(struct hci_uart *hu, bool enable)
> > 		BT_DBG("Setting RTS: %s", status ? "failed" : "success");
> > 
> > 		/* Re-enable hardware flow control */
> > -		ktermios = tty->termios;
> > +		ktermios = real_tty->termios;
> > 		ktermios.c_cflag |= CRTSCTS;
> > -		status = tty_set_termios(tty, &ktermios);
> > +		status = tty_set_termios(real_tty, &ktermios);
> > 		BT_DBG("Enabling hardware flow control: %s",
> > 		       status ? "failed" : "success");
> > 	}
> > @@ -367,9 +381,12 @@ void hci_uart_set_speeds(struct hci_uart *hu, unsigned int init_speed,
> > 
> > void hci_uart_set_baudrate(struct hci_uart *hu, unsigned int speed)
> > {
> > -	struct tty_struct *tty = hu->tty;
> > +	struct tty_struct *tty;
> > 	struct ktermios ktermios;
> > 
> > +	/* termios should be set from slave side if tty driver is pty */
> > +	tty = hci_uart_get_real_tty(hu->tty);
> > +
> 
> didn’t we conclude that allowing the HCI line discipline on a PTY master isn't worth the effort? The ptm_unix98_ops doesn’t have the .set_termios and thus, just check that ops->set_termios is present in hci_uart_tty_open and if not fail with EOPNOTSUPP like we do for missing ops->write.
> 
> Regards
> 
> Marcel
> 
Hi Marcel,

I thought there might be some cases that reach here even returning error in
hci_uart_tty_open(). Let me fix it from hci_uart_tty_open.

Thanks,
Myungho


^ permalink raw reply	[flat|nested] 3+ messages in thread

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2019-02-02  7:28 [PATCH v2] Bluetooth: hci_uart: Switch pty driver to slave side in tty_set_termios() Myungho Jung
2019-02-02 12:15 ` Marcel Holtmann
2019-02-03  3:30   ` Myungho Jung

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