Merge tag 'linux-can-fixes-for-6.19-20260115' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can

Marc Kleine-Budde says:

====================
pull-request: can 2026-01-15

this is a pull request of 4 patches for net/main, it super-seeds the
"can 2026-01-14" pull request. The dev refcount leak in patch #3 is
fixed.

The first 3 patches are by Oliver Hartkopp and revert the approach to
instantly reject unsupported CAN frames introduced in
net-next-for-v6.19 and replace it by placing the needed data into the
CAN specific ml_priv.

The last patch is by Tetsuo Handa and fixes a J1939 refcount leak for
j1939_session in session deactivation upon receiving the second RTS.

linux-can-fixes-for-6.19-20260115

* tag 'linux-can-fixes-for-6.19-20260115' of git://git.kernel.org/pub/scm/linux/kernel/git/mkl/linux-can:
  net: can: j1939: j1939_xtp_rx_rts_session_active(): deactivate session upon receiving the second rts
  can: raw: instantly reject disabled CAN frames
  can: propagate CAN device capabilities via ml_priv
  Revert "can: raw: instantly reject unsupported CAN frames"
====================

Link: https://patch.msgid.link/20260115090603.1124860-1-mkl@pengutronix.de
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

2 files changed, 19 insertions, 42 deletions

diff --git a/net/can/j1939/transport.c b/net/can/j1939/transport.c
index 613a911dda10..8656ab388c83 100644
--- a/net/can/j1939/transport.c
+++ b/net/can/j1939/transport.c
@@ -1695,8 +1695,16 @@ static int j1939_xtp_rx_rts_session_active(struct j1939_session *session,
 
 		j1939_session_timers_cancel(session);
 		j1939_session_cancel(session, J1939_XTP_ABORT_BUSY);
-		if (session->transmission)
+		if (session->transmission) {
 			j1939_session_deactivate_activate_next(session);
+		} else if (session->state == J1939_SESSION_WAITING_ABORT) {
+			/* Force deactivation for the receiver.
+			 * If we rely on the timer starting in j1939_session_cancel,
+			 * a second RTS call here will cancel that timer and fail
+			 * to restart it because the state is already WAITING_ABORT.
+			 */
+			j1939_session_deactivate_activate_next(session);
+		}
 
 		return -EBUSY;
 	}
diff --git a/net/can/raw.c b/net/can/raw.c
index be1ef7cf4204..12293363413c 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -49,8 +49,8 @@
 #include <linux/if_arp.h>
 #include <linux/skbuff.h>
 #include <linux/can.h>
+#include <linux/can/can-ml.h>
 #include <linux/can/core.h>
-#include <linux/can/dev.h> /* for can_is_canxl_dev_mtu() */
 #include <linux/can/skb.h>
 #include <linux/can/raw.h>
 #include <net/sock.h>
@@ -892,58 +892,21 @@ 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)
-{
-	/* 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))
+	if (can_is_can_skb(skb) && can_cap_enabled(dev, CAN_CAP_CC))
 		return CAN_MTU;
 
 	/* CAN FD */
 	if (ro->fd_frames && can_is_canfd_skb(skb) &&
-	    raw_dev_fd_enabled(dev, priv))
+	    can_cap_enabled(dev, CAN_CAP_FD))
 		return CANFD_MTU;
 
 	/* CAN XL */
 	if (ro->xl_frames && can_is_canxl_skb(skb) &&
-	    raw_dev_xl_enabled(dev, priv))
+	    can_cap_enabled(dev, CAN_CAP_XL))
 		return CANXL_MTU;
 
 	return 0;
@@ -982,6 +945,12 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	if (!dev)
 		return -ENXIO;
 
+	/* no sending on a CAN device in read-only mode */
+	if (can_cap_enabled(dev, CAN_CAP_RO)) {
+		err = -EACCES;
+		goto put_dev;
+	}
+
 	skb = sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv),
 				  msg->msg_flags & MSG_DONTWAIT, &err);
 	if (!skb)