linux-kernel - [PATCH 2/2] can: dev: drop tx skb if in listen only mode

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Date:   Fri, 13 May 2022 23:23:55 +0900
From:   Vincent Mailhol <mailhol.vincent@...adoo.fr>
To:     Marc Kleine-Budde <mkl@...gutronix.de>
Cc:     linux-can@...r.kernel.org, linux-kernel@...r.kernel.org,
        Max Staudt <max@...as.org>,
        Vincent Mailhol <mailhol.vincent@...adoo.fr>
Subject: [PATCH 2/2] can: dev: drop tx skb if in listen only mode

Frames can be directly injected to a can driver via the packet
socket. By doing that, it is possible to reach the
net_device_ops::ndo_start_xmit function even if the driver is
configure in listen only mode.

Add a check in can_dropped_invalid_skb() and to discard the skb if
CAN_CTRLMODE_LISTENONLY is set.

Signed-off-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>
---
 include/linux/can/dev.h | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index bbe27e22c7a7..c3ed48e54c29 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -161,6 +161,7 @@ static inline bool can_dropped_invalid_skb(struct net_device *dev,
 					   struct sk_buff *skb)
 {
 	const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+	struct can_priv *priv = netdev_priv(dev);
 
 	if (skb->protocol == htons(ETH_P_CAN)) {
 		if (unlikely(skb->len != CAN_MTU ||
@@ -174,8 +175,13 @@ static inline bool can_dropped_invalid_skb(struct net_device *dev,
 		goto inval_skb;
 	}
 
-	if (!can_skb_headroom_valid(dev, skb))
+	if (!can_skb_headroom_valid(dev, skb)) {
+		goto inval_skb;
+	} else if (priv->ctrlmode & CAN_CTRLMODE_LISTENONLY) {
+		netdev_info_once(dev,
+				 "interface in listen only mode, dropping skb\n");
 		goto inval_skb;
+	}
 
 	return false;
 
-- 
2.35.1