Commit 7f2d38eb authored by Oliver Hartkopp's avatar Oliver Hartkopp Committed by David S. Miller
Browse files

can: add sanity checks 



Even though the CAN netlayer only deals with CAN netdevices, the 
netlayer interface to the userspace and to the device layer should 
perform some sanity checks.

This patch adds several sanity checks that mainly prevent userspace apps 
to send broken content into the system that may be misinterpreted by 
some other userspace application.

Signed-off-by: default avatarOliver Hartkopp <oliver.hartkopp@volkswagen.de>
Signed-off-by: default avatarUrs Thuermann <urs.thuermann@volkswagen.de>
Acked-by: default avatarAndre Naujoks <nautsch@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent c5a78ac0

net/can/af_can.c

+10 −0
Original line number Diff line number Diff line
@@ -205,12 +205,19 @@ static int can_create(struct net *net, struct socket *sock, int protocol) 
 *  -ENOBUFS on full driver queue (see net_xmit_errno())

 *  -ENOMEM when local loopback failed at calling skb_clone()

 *  -EPERM when trying to send on a non-CAN interface

 *  -EINVAL when the skb->data does not contain a valid CAN frame

 */

int can_send(struct sk_buff *skb, int loop)

{

	struct sk_buff *newskb = NULL;

	struct can_frame *cf = (struct can_frame *)skb->data;

	int err;



	if (skb->len != sizeof(struct can_frame) || cf->can_dlc > 8) {

		kfree_skb(skb);

		return -EINVAL;

	}



	if (skb->dev->type != ARPHRD_CAN) {

		kfree_skb(skb);

		return -EPERM;
@@ -605,6 +612,7 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev, 
		   struct packet_type *pt, struct net_device *orig_dev)

{

	struct dev_rcv_lists *d;

	struct can_frame *cf = (struct can_frame *)skb->data;

	int matches;



	if (dev->type != ARPHRD_CAN || dev_net(dev) != &init_net) {
@@ -612,6 +620,8 @@ static int can_rcv(struct sk_buff *skb, struct net_device *dev, 
		return 0;

	}



	BUG_ON(skb->len != sizeof(struct can_frame) || cf->can_dlc > 8);



	/* update statistics */

	can_stats.rx_frames++;

	can_stats.rx_frames_delta++;

net/can/bcm.c

+19 −4
Original line number Diff line number Diff line
@@ -826,6 +826,10 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg, 
		for (i = 0; i < msg_head->nframes; i++) {

			err = memcpy_fromiovec((u8 *)&op->frames[i],

					       msg->msg_iov, CFSIZ);



			if (op->frames[i].can_dlc > 8)

				err = -EINVAL;



			if (err < 0)

				return err;
@@ -858,6 +862,10 @@ static int bcm_tx_setup(struct bcm_msg_head *msg_head, struct msghdr *msg, 
		for (i = 0; i < msg_head->nframes; i++) {

			err = memcpy_fromiovec((u8 *)&op->frames[i],

					       msg->msg_iov, CFSIZ);



			if (op->frames[i].can_dlc > 8)

				err = -EINVAL;



			if (err < 0) {

				if (op->frames != &op->sframe)

					kfree(op->frames);
@@ -1164,9 +1172,12 @@ static int bcm_tx_send(struct msghdr *msg, int ifindex, struct sock *sk) 


	skb->dev = dev;

	skb->sk  = sk;

	can_send(skb, 1); /* send with loopback */

	err = can_send(skb, 1); /* send with loopback */

	dev_put(dev);



	if (err)

		return err;



	return CFSIZ + MHSIZ;

}
@@ -1185,6 +1196,10 @@ static int bcm_sendmsg(struct kiocb *iocb, struct socket *sock, 
	if (!bo->bound)

		return -ENOTCONN;



	/* check for valid message length from userspace */

	if (size < MHSIZ || (size - MHSIZ) % CFSIZ)

		return -EINVAL;



	/* check for alternative ifindex for this bcm_op */



	if (!ifindex && msg->msg_name) {
@@ -1259,8 +1274,8 @@ static int bcm_sendmsg(struct kiocb *iocb, struct socket *sock, 
		break;



	case TX_SEND:

		/* we need at least one can_frame */

		if (msg_head.nframes < 1)

		/* we need exactly one can_frame behind the msg head */

		if ((msg_head.nframes != 1) || (size != CFSIZ + MHSIZ))

			ret = -EINVAL;

		else

			ret = bcm_tx_send(msg, ifindex, sk);

net/can/raw.c

+3 −0
Original line number Diff line number Diff line
@@ -632,6 +632,9 @@ static int raw_sendmsg(struct kiocb *iocb, struct socket *sock, 
	} else

		ifindex = ro->ifindex;



	if (size != sizeof(struct can_frame))

		return -EINVAL;



	dev = dev_get_by_index(&init_net, ifindex);

	if (!dev)

		return -ENXIO;

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