can: Unify droping of invalid tx skbs and netdev stats

To prevent the CAN drivers to operate on invalid socketbuffers the skbs are
now checked and silently dropped at the xmit-function consistently.

Also the netdev stats are consistently using the CAN data length code (dlc)
for [rx|tx]_bytes now.

Signed-off-by: Oliver Hartkopp <oliver@hartkopp.net>
Acked-by: Wolfgang Grandegger <wg@grandegger.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 3db7767d2a17..7e7c98a3e908 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -60,6 +60,21 @@ struct can_priv {
  */
 #define get_can_dlc(i)  (min_t(__u8, (i), 8))
 
+/* Drop a given socketbuffer if it does not contain a valid CAN frame. */
+static inline int can_dropped_invalid_skb(struct net_device *dev,
+                                          struct sk_buff *skb)
+{
+        const struct can_frame *cf = (struct can_frame *)skb->data;
+
+        if (unlikely(skb->len != sizeof(*cf) || cf->can_dlc > 8)) {
+                kfree_skb(skb);
+                dev->stats.tx_dropped++;
+                return 1;
+        }
+
+        return 0;
+}
+
 struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max);
 void free_candev(struct net_device *dev);