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: Oliver Hartkopp <oliver.hartkopp@volkswagen.de>
Signed-off-by: Urs Thuermann <urs.thuermann@volkswagen.de>
Acked-by: Andre Naujoks <nautsch@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/can/af_can.c b/net/can/af_can.c
index 7e8ca28..484bbf6 100644
--- a/net/can/af_can.c
+++ b/net/can/af_can.c
@@ -205,12 +205,19 @@
* -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 @@
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 @@
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++;
diff --git a/net/can/bcm.c b/net/can/bcm.c
index d9a3a9d..72c2ce9 100644
--- a/net/can/bcm.c
+++ b/net/can/bcm.c
@@ -298,7 +298,7 @@
if (head->nframes) {
/* can_frames starting here */
- firstframe = (struct can_frame *) skb_tail_pointer(skb);
+ firstframe = (struct can_frame *)skb_tail_pointer(skb);
memcpy(skb_put(skb, datalen), frames, datalen);
@@ -826,6 +826,10 @@
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 @@
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 @@
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 @@
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 @@
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);
diff --git a/net/can/raw.c b/net/can/raw.c
index 69877b8..3e46ee3 100644
--- a/net/can/raw.c
+++ b/net/can/raw.c
@@ -632,6 +632,9 @@
} else
ifindex = ro->ifindex;
+ if (size != sizeof(struct can_frame))
+ return -EINVAL;
+
dev = dev_get_by_index(&init_net, ifindex);
if (!dev)
return -ENXIO;