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/bcm.c b/net/can/bcm.c
index d9a3a9d..72c2ce90 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);
