can: raw: add CAN XL support

Enable CAN_RAW sockets to read and write CAN XL frames analogue to the
CAN FD extension (new CAN_RAW_XL_FRAMES sockopt).

A CAN XL network interface is capable to handle Classical CAN, CAN FD and
CAN XL frames. When CAN_RAW_XL_FRAMES is enabled, the CAN_RAW socket checks
whether the addressed CAN network interface is capable to handle the
provided CAN frame.

In opposite to the fixed number of bytes for
- CAN frames (CAN_MTU = sizeof(struct can_frame))
- CAN FD frames (CANFD_MTU = sizeof(struct can_frame))
the number of bytes when reading/writing CAN XL frames depends on the
number of data bytes. For efficiency reasons the length of the struct
canxl_frame is truncated to the needed size for read/write operations.
This leads to a calculated size of CANXL_HDR_SIZE + canxl_frame::len which
is enforced on write() operations and guaranteed on read() operations.

NB: Valid length values are 1 .. 2048 (CANXL_MIN_DLEN .. CANXL_MAX_DLEN).

Acked-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/all/20220912170725.120748-8-socketcan@hartkopp.net
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

include/uapi/linux/can/raw.h

@@ -62,6 +62,7 @@ enum {
 	CAN_RAW_RECV_OWN_MSGS,	/* receive my own msgs (default:off) */
 	CAN_RAW_FD_FRAMES,	/* allow CAN FD frames (default:off) */
 	CAN_RAW_JOIN_FILTERS,	/* all filters must match to trigger */
+	CAN_RAW_XL_FRAMES,	/* allow CAN XL frames (default:off) */
 };
 
 #endif /* !_UAPI_CAN_RAW_H */

net/can/raw.c

@@ -50,6 +50,7 @@
 #include <linux/skbuff.h>
 #include <linux/can.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>
@@ -87,6 +88,7 @@ struct raw_sock {
 	int loopback;
 	int recv_own_msgs;
 	int fd_frames;
+	int xl_frames;
 	int join_filters;
 	int count;                 /* number of active filters */
 	struct can_filter dfilter; /* default/single filter */
@@ -129,8 +131,9 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
 	if (!ro->recv_own_msgs && oskb->sk == sk)
 		return;
 
-	/* do not pass non-CAN2.0 frames to a legacy socket */
-	if (!ro->fd_frames && oskb->len != CAN_MTU)
+	/* make sure to not pass oversized frames to the socket */
+	if ((can_is_canfd_skb(oskb) && !ro->fd_frames && !ro->xl_frames) ||
+	    (can_is_canxl_skb(oskb) && !ro->xl_frames))
 		return;
 
 	/* eliminate multiple filter matches for the same skb */
@@ -345,6 +348,7 @@ static int raw_init(struct sock *sk)
 	ro->loopback         = 1;
 	ro->recv_own_msgs    = 0;
 	ro->fd_frames        = 0;
+	ro->xl_frames        = 0;
 	ro->join_filters     = 0;
 
 	/* alloc_percpu provides zero'ed memory */
@@ -668,6 +672,15 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
 
 		break;
 
+	case CAN_RAW_XL_FRAMES:
+		if (optlen != sizeof(ro->xl_frames))
+			return -EINVAL;
+
+		if (copy_from_sockptr(&ro->xl_frames, optval, optlen))
+			return -EFAULT;
+
+		break;
+
 	case CAN_RAW_JOIN_FILTERS:
 		if (optlen != sizeof(ro->join_filters))
 			return -EINVAL;
@@ -750,6 +763,12 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
 		val = &ro->fd_frames;
 		break;
 
+	case CAN_RAW_XL_FRAMES:
+		if (len > sizeof(int))
+			len = sizeof(int);
+		val = &ro->xl_frames;
+		break;
+
 	case CAN_RAW_JOIN_FILTERS:
 		if (len > sizeof(int))
 			len = sizeof(int);
@@ -775,7 +794,11 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	struct sk_buff *skb;
 	struct net_device *dev;
 	int ifindex;
-	int err;
+	int err = -EINVAL;
+
+	/* check for valid CAN frame sizes */
+	if (size < CANXL_HDR_SIZE + CANXL_MIN_DLEN || size > CANXL_MTU)
+		return -EINVAL;
 
 	if (msg->msg_name) {
 		DECLARE_SOCKADDR(struct sockaddr_can *, addr, msg->msg_name);
@@ -795,15 +818,6 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	if (!dev)
 		return -ENXIO;
 
-	err = -EINVAL;
-	if (ro->fd_frames && dev->mtu == CANFD_MTU) {
-		if (unlikely(size != CANFD_MTU && size != CAN_MTU))
-			goto put_dev;
-	} else {
-		if (unlikely(size != CAN_MTU))
-			goto put_dev;
-	}
-
 	skb = sock_alloc_send_skb(sk, size + sizeof(struct can_skb_priv),
 				  msg->msg_flags & MSG_DONTWAIT, &err);
 	if (!skb)
@@ -813,10 +827,27 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	can_skb_prv(skb)->ifindex = dev->ifindex;
 	can_skb_prv(skb)->skbcnt = 0;
 
+	/* fill the skb before testing for valid CAN frames */
 	err = memcpy_from_msg(skb_put(skb, size), msg, size);
 	if (err < 0)
 		goto free_skb;
 
+	err = -EINVAL;
+	if (ro->xl_frames && can_is_canxl_dev_mtu(dev->mtu)) {
+		/* CAN XL, CAN FD and Classical CAN */
+		if (!can_is_canxl_skb(skb) && !can_is_canfd_skb(skb) &&
+		    !can_is_can_skb(skb))
+			goto free_skb;
+	} else if (ro->fd_frames && dev->mtu == CANFD_MTU) {
+		/* CAN FD and Classical CAN */
+		if (!can_is_canfd_skb(skb) && !can_is_can_skb(skb))
+			goto free_skb;
+	} else {
+		/* Classical CAN */
+		if (!can_is_can_skb(skb))
+			goto free_skb;
+	}
+
 	sockcm_init(&sockc, sk);
 	if (msg->msg_controllen) {
 		err = sock_cmsg_send(sk, msg, &sockc);