From: Oliver Hartkopp For real CAN interfaces the CAN_CTRLMODE_FD and CAN_CTRLMODE_XL control modes indicate whether an interface can handle those CAN FD/XL frames. In the case a CAN XL interface is configured in CANXL-only mode with disabled error-signalling neither CAN CC nor CAN FD frames can be sent. The checks are now performed on CAN_RAW sockets to give an instant feedback to the user when writing unsupported CAN frames to the interface or when the CAN interface is in read-only mode. Fixes: 1a620a723853 ("can: raw: instantly reject unsupported CAN frames") Cc: Marc Kleine-Budde Cc: Arnd Bergmann Cc: Vincent Mailhol Signed-off-by: Oliver Hartkopp Link: https://patch.msgid.link/20260109144135.8495-4-socketcan@hartkopp.net Signed-off-by: Marc Kleine-Budde --- net/can/raw.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) diff --git a/net/can/raw.c b/net/can/raw.c index f36a83d3447c..d66036da6753 100644 --- a/net/can/raw.c +++ b/net/can/raw.c @@ -49,8 +49,8 @@ #include #include #include +#include #include -#include /* for can_is_canxl_dev_mtu() */ #include #include #include @@ -892,20 +892,21 @@ static void raw_put_canxl_vcid(struct raw_sock *ro, struct sk_buff *skb) } } -static unsigned int raw_check_txframe(struct raw_sock *ro, struct sk_buff *skb, int mtu) +static unsigned int raw_check_txframe(struct raw_sock *ro, struct sk_buff *skb, + struct net_device *dev) { - /* Classical CAN -> no checks for flags and device capabilities */ - if (can_is_can_skb(skb)) + /* Classical CAN */ + if (can_is_can_skb(skb) && can_cap_enabled(dev, CAN_CAP_CC)) return CAN_MTU; - /* CAN FD -> needs to be enabled and a CAN FD or CAN XL device */ + /* CAN FD */ if (ro->fd_frames && can_is_canfd_skb(skb) && - (mtu == CANFD_MTU || can_is_canxl_dev_mtu(mtu))) + can_cap_enabled(dev, CAN_CAP_FD)) return CANFD_MTU; - /* CAN XL -> needs to be enabled and a CAN XL device */ + /* CAN XL */ if (ro->xl_frames && can_is_canxl_skb(skb) && - can_is_canxl_dev_mtu(mtu)) + can_cap_enabled(dev, CAN_CAP_XL)) return CANXL_MTU; return 0; @@ -944,6 +945,10 @@ 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)) + return -EACCES; + skb = sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv), msg->msg_flags & MSG_DONTWAIT, &err); if (!skb) @@ -961,7 +966,7 @@ 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, READ_ONCE(dev->mtu)); + txmtu = raw_check_txframe(ro, skb, dev); if (!txmtu) goto free_skb; -- 2.51.0