Revert "can: raw: instantly reject unsupported CAN frames"

This reverts commit 1a620a723853a0f49703c317d52dc6b9602cbaa8

and its follow-up fixes for the introduced dependency issues.

commit 1a620a723853 ("can: raw: instantly reject unsupported CAN frames")
commit cb2dc6d2869a ("can: Kconfig: select CAN driver infrastructure by default")
commit 6abd4577bccc ("can: fix build dependency")
commit 5a5aff6338c0 ("can: fix build dependency")

The entire problem was caused by the requirement that a new network layer
feature needed to know about the protocol capabilities of the CAN devices.
Instead of accessing CAN device internal data structures which caused the
dependency problems a better approach has been developed which makes use of
CAN specific ml_priv data which is accessible from both sides.

Cc: Marc Kleine-Budde <mkl@pengutronix.de>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Vincent Mailhol <mailhol@kernel.org>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://patch.msgid.link/20260109144135.8495-2-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

1 files changed, 8 insertions, 46 deletions

diff --git a/net/can/raw.c b/net/can/raw.c
index be1ef7cf4204..f36a83d3447c 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -892,58 +892,20 @@ static void raw_put_canxl_vcid(struct raw_sock *ro, struct sk_buff *skb)
 	}
 }
 
-static inline bool raw_dev_cc_enabled(struct net_device *dev,
-				      struct can_priv *priv)
+static unsigned int raw_check_txframe(struct raw_sock *ro, struct sk_buff *skb, int mtu)
 {
-	/* The CANXL-only mode disables error-signalling on the CAN bus
-	 * which is needed to send CAN CC/FD frames
-	 */
-	if (priv)
-		return !can_dev_in_xl_only_mode(priv);
-
-	/* virtual CAN interfaces always support CAN CC */
-	return true;
-}
-
-static inline bool raw_dev_fd_enabled(struct net_device *dev,
-				      struct can_priv *priv)
-{
-	/* check FD ctrlmode on real CAN interfaces */
-	if (priv)
-		return (priv->ctrlmode & CAN_CTRLMODE_FD);
-
-	/* check MTU for virtual CAN FD interfaces */
-	return (READ_ONCE(dev->mtu) >= CANFD_MTU);
-}
-
-static inline bool raw_dev_xl_enabled(struct net_device *dev,
-				      struct can_priv *priv)
-{
-	/* check XL ctrlmode on real CAN interfaces */
-	if (priv)
-		return (priv->ctrlmode & CAN_CTRLMODE_XL);
-
-	/* check MTU for virtual CAN XL interfaces */
-	return can_is_canxl_dev_mtu(READ_ONCE(dev->mtu));
-}
-
-static unsigned int raw_check_txframe(struct raw_sock *ro, struct sk_buff *skb,
-				      struct net_device *dev)
-{
-	struct can_priv *priv = safe_candev_priv(dev);
-
-	/* Classical CAN */
-	if (can_is_can_skb(skb) && raw_dev_cc_enabled(dev, priv))
+	/* Classical CAN -> no checks for flags and device capabilities */
+	if (can_is_can_skb(skb))
 		return CAN_MTU;
 
-	/* CAN FD */
+	/* CAN FD -> needs to be enabled and a CAN FD or CAN XL device */
 	if (ro->fd_frames && can_is_canfd_skb(skb) &&
-	    raw_dev_fd_enabled(dev, priv))
+	    (mtu == CANFD_MTU || can_is_canxl_dev_mtu(mtu)))
 		return CANFD_MTU;
 
-	/* CAN XL */
+	/* CAN XL -> needs to be enabled and a CAN XL device */
 	if (ro->xl_frames && can_is_canxl_skb(skb) &&
-	    raw_dev_xl_enabled(dev, priv))
+	    can_is_canxl_dev_mtu(mtu))
 		return CANXL_MTU;
 
 	return 0;
@@ -999,7 +961,7 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	err = -EINVAL;
 
 	/* check for valid CAN (CC/FD/XL) frame content */
-	txmtu = raw_check_txframe(ro, skb, dev);
+	txmtu = raw_check_txframe(ro, skb, READ_ONCE(dev->mtu));
 	if (!txmtu)
 		goto free_skb;