[PATCH v2] can: raw: fix CAN FD frame transmissions over CAN XL devices

[PATCH v2] can: raw: fix CAN FD frame transmissions over CAN XL devices

[Oliver Hartkopp]

A CAN XL device is always capable to process CAN FD frames. The former
check when sending CAN FD frames relied on the existence of a CAN FD
device and did not check for a CAN XL device that would be correct too.

With this patch the CAN FD feature is enabled automatically when CAN XL
is switched on - and CAN FD cannot be switch off while CAN XL is enabled.

This precondition also leads to a clean up and reduction of checks in the
hot path in raw_rcv() and raw_sendmsg().

Fixes: 626332696d75 ("can: raw: add CAN XL support")
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
---

V2: fixed typo: devive -> device

net/can/raw.c | 45 ++++++++++++++++++++++++++++++---------------
 1 file changed, 30 insertions(+), 15 deletions(-)

diff --git a/net/can/raw.c b/net/can/raw.c
index 81071cdb0301..c505d315a7a9 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -130,11 +130,11 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
 	/* check the received tx sock reference */
 	if (!ro->recv_own_msgs && oskb->sk == sk)
 		return;
 
 	/* make sure to not pass oversized frames to the socket */
-	if ((can_is_canfd_skb(oskb) && !ro->fd_frames && !ro->xl_frames) ||
+	if ((can_is_canfd_skb(oskb) && !ro->fd_frames) ||
 	    (can_is_canxl_skb(oskb) && !ro->xl_frames))
 		return;
 
 	/* eliminate multiple filter matches for the same skb */
 	if (this_cpu_ptr(ro->uniq)->skb == oskb &&
@@ -668,19 +668,27 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
 			return -EINVAL;
 
 		if (copy_from_sockptr(&ro->fd_frames, optval, optlen))
 			return -EFAULT;
 
+		/* Enabling CAN XL includes CAN FD */
+		if (ro->xl_frames && !ro->fd_frames) {
+			ro->fd_frames = ro->xl_frames;
+			return -EINVAL;
+		}
 		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;
 
+		/* Enabling CAN XL includes CAN FD */
+		if (ro->xl_frames)
+			ro->fd_frames = ro->xl_frames;
 		break;
 
 	case CAN_RAW_JOIN_FILTERS:
 		if (optlen != sizeof(ro->join_filters))
 			return -EINVAL;
@@ -784,10 +792,29 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
 	if (copy_to_user(optval, val, len))
 		return -EFAULT;
 	return 0;
 }
 
+static bool raw_bad_txframe(struct raw_sock *ro, struct sk_buff *skb, int mtu)
+{
+	/* Classical CAN -> no checks for flags and device capabilities */
+	if (can_is_can_skb(skb))
+		return false;
+
+	/* CAN FD -> needs to be enabled and a CAN FD or CAN XL device */
+	if (can_is_canfd_skb(skb) && ro->fd_frames &&
+	    (mtu == CANFD_MTU || can_is_canxl_dev_mtu(mtu)))
+		return false;
+
+	/* CAN XL -> needs to be enabled and a CAN XL device */
+	if (can_is_canxl_skb(skb) && ro->xl_frames &&
+	    can_is_canxl_dev_mtu(mtu))
+		return false;
+
+	return true;
+}
+
 static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 {
 	struct sock *sk = sock->sk;
 	struct raw_sock *ro = raw_sk(sk);
 	struct sockcm_cookie sockc;
@@ -831,24 +858,12 @@ static int raw_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
 	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;
-	}
+	if (raw_bad_txframe(ro, skb, dev->mtu))
+		goto free_skb;
 
 	sockcm_init(&sockc, sk);
 	if (msg->msg_controllen) {
 		err = sock_cmsg_send(sk, msg, &sockc);
 		if (unlikely(err))
-- 
2.39.0

Re: [PATCH v2] can: raw: fix CAN FD frame transmissions over CAN XL devices

[Marc Kleine-Budde]

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On 31.01.2023 10:18:24, Oliver Hartkopp wrote:
> A CAN XL device is always capable to process CAN FD frames. The former
> check when sending CAN FD frames relied on the existence of a CAN FD
> device and did not check for a CAN XL device that would be correct too.
> 
> With this patch the CAN FD feature is enabled automatically when CAN XL
> is switched on - and CAN FD cannot be switch off while CAN XL is enabled.
> 
> This precondition also leads to a clean up and reduction of checks in the
> hot path in raw_rcv() and raw_sendmsg().
> 
> Fixes: 626332696d75 ("can: raw: add CAN XL support")
> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
> ---
> 
> V2: fixed typo: devive -> device
> 
> net/can/raw.c | 45 ++++++++++++++++++++++++++++++---------------
>  1 file changed, 30 insertions(+), 15 deletions(-)
> 
> diff --git a/net/can/raw.c b/net/can/raw.c
> index 81071cdb0301..c505d315a7a9 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -130,11 +130,11 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
>  	/* check the received tx sock reference */
>  	if (!ro->recv_own_msgs && oskb->sk == sk)
>  		return;
>  
>  	/* make sure to not pass oversized frames to the socket */
> -	if ((can_is_canfd_skb(oskb) && !ro->fd_frames && !ro->xl_frames) ||
> +	if ((can_is_canfd_skb(oskb) && !ro->fd_frames) ||
>  	    (can_is_canxl_skb(oskb) && !ro->xl_frames))
>  		return;
>  
>  	/* eliminate multiple filter matches for the same skb */
>  	if (this_cpu_ptr(ro->uniq)->skb == oskb &&
> @@ -668,19 +668,27 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>  			return -EINVAL;
>  
>  		if (copy_from_sockptr(&ro->fd_frames, optval, optlen))
>  			return -EFAULT;
>  
> +		/* Enabling CAN XL includes CAN FD */
> +		if (ro->xl_frames && !ro->fd_frames) {
> +			ro->fd_frames = ro->xl_frames;
> +			return -EINVAL;
> +		}

This looks a bit weird. Maybe copy to a local variable first, then
check, then assign ->fd_frames or exit with error (instead of rolling
back)?

Marc

-- 
Pengutronix e.K.                 | Marc Kleine-Budde           |
Embedded Linux                   | https://www.pengutronix.de  |
Vertretung West/Dortmund         | Phone: +49-231-2826-924     |
Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-5555 |

[-- Attachment #2: signature.asc --]
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Re: [PATCH v2] can: raw: fix CAN FD frame transmissions over CAN XL devices

[Oliver Hartkopp]

On 1/31/23 12:06, Marc Kleine-Budde wrote:
> On 31.01.2023 10:18:24, Oliver Hartkopp wrote:
>> A CAN XL device is always capable to process CAN FD frames. The former
>> check when sending CAN FD frames relied on the existence of a CAN FD
>> device and did not check for a CAN XL device that would be correct too.
>>
>> With this patch the CAN FD feature is enabled automatically when CAN XL
>> is switched on - and CAN FD cannot be switch off while CAN XL is enabled.
>>
>> This precondition also leads to a clean up and reduction of checks in the
>> hot path in raw_rcv() and raw_sendmsg().
>>
>> Fixes: 626332696d75 ("can: raw: add CAN XL support")
>> Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
>> ---
>>
>> V2: fixed typo: devive -> device
>>
>> net/can/raw.c | 45 ++++++++++++++++++++++++++++++---------------
>>   1 file changed, 30 insertions(+), 15 deletions(-)
>>
>> diff --git a/net/can/raw.c b/net/can/raw.c
>> index 81071cdb0301..c505d315a7a9 100644
>> --- a/net/can/raw.c
>> +++ b/net/can/raw.c
>> @@ -130,11 +130,11 @@ static void raw_rcv(struct sk_buff *oskb, void *data)
>>   	/* check the received tx sock reference */
>>   	if (!ro->recv_own_msgs && oskb->sk == sk)
>>   		return;
>>   
>>   	/* make sure to not pass oversized frames to the socket */
>> -	if ((can_is_canfd_skb(oskb) && !ro->fd_frames && !ro->xl_frames) ||
>> +	if ((can_is_canfd_skb(oskb) && !ro->fd_frames) ||
>>   	    (can_is_canxl_skb(oskb) && !ro->xl_frames))
>>   		return;
>>   
>>   	/* eliminate multiple filter matches for the same skb */
>>   	if (this_cpu_ptr(ro->uniq)->skb == oskb &&
>> @@ -668,19 +668,27 @@ static int raw_setsockopt(struct socket *sock, int level, int optname,
>>   			return -EINVAL;
>>   
>>   		if (copy_from_sockptr(&ro->fd_frames, optval, optlen))
>>   			return -EFAULT;
>>   
>> +		/* Enabling CAN XL includes CAN FD */
>> +		if (ro->xl_frames && !ro->fd_frames) {
>> +			ro->fd_frames = ro->xl_frames;
>> +			return -EINVAL;
>> +		}
> 
> This looks a bit weird. Maybe copy to a local variable first, then
> check, then assign ->fd_frames or exit with error (instead of rolling
> back)?
>

Changed in V4.

Thanks & BR,
Oliver