candev: add/update helpers for CAN FD

- update sanity checks
- add DLC to length conversion helpers
  - can_dlc2len() - get data length from can_dlc with sanitized can_dlc
  - can_len2dlc() - map the sanitized data length to an appropriate DLC

Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 25 insertions, 8 deletions

diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 5d2efe7..ee5a771 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -61,23 +61,40 @@ struct can_priv {
  * To be used in the CAN netdriver receive path to ensure conformance with
  * ISO 11898-1 Chapter 8.4.2.3 (DLC field)
  */
-#define get_can_dlc(i)	(min_t(__u8, (i), 8))
+#define get_can_dlc(i)		(min_t(__u8, (i), CAN_MAX_DLC))
+#define get_canfd_dlc(i)	(min_t(__u8, (i), CANFD_MAX_DLC))
 
 /* 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;
-	}
+	const struct canfd_frame *cfd = (struct canfd_frame *)skb->data;
+
+	if (skb->protocol == htons(ETH_P_CAN)) {
+		if (unlikely(skb->len != CAN_MTU ||
+			     cfd->len > CAN_MAX_DLEN))
+			goto inval_skb;
+	} else if (skb->protocol == htons(ETH_P_CANFD)) {
+		if (unlikely(skb->len != CANFD_MTU ||
+			     cfd->len > CANFD_MAX_DLEN))
+			goto inval_skb;
+	} else
+		goto inval_skb;
 
 	return 0;
+
+inval_skb:
+	kfree_skb(skb);
+	dev->stats.tx_dropped++;
+	return 1;
 }
 
+/* get data length from can_dlc with sanitized can_dlc */
+u8 can_dlc2len(u8 can_dlc);
+
+/* map the sanitized data length to an appropriate data length code */
+u8 can_len2dlc(u8 len);
+
 struct net_device *alloc_candev(int sizeof_priv, unsigned int echo_skb_max);
 void free_candev(struct net_device *dev);