ipv4: Use standard iovec primitive in raw_probe_proto_opt

The function raw_probe_proto_opt tries to extract the first two
bytes from the user input in order to seed the IPsec lookup for
ICMP packets.  In doing so it's processing iovec by hand and
overcomplicating things.

This patch replaces the manual iovec processing with a call to
memcpy_fromiovecend.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/raw.c

@@ -422,48 +422,20 @@ static int raw_send_hdrinc(struct sock *sk, struct flowi4 *fl4,
 
 static int raw_probe_proto_opt(struct flowi4 *fl4, struct msghdr *msg)
 {
-	struct iovec *iov;
-	u8 __user *type = NULL;
-	u8 __user *code = NULL;
-	int probed = 0;
-	unsigned int i;
+	struct icmphdr icmph;
+	int err;
 
-	if (!msg->msg_iov)
+	if (fl4->flowi4_proto != IPPROTO_ICMP)
 		return 0;
 
-	for (i = 0; i < msg->msg_iovlen; i++) {
-		iov = &msg->msg_iov[i];
-		if (!iov)
-			continue;
-
-		switch (fl4->flowi4_proto) {
-		case IPPROTO_ICMP:
-			/* check if one-byte field is readable or not. */
-			if (iov->iov_base && iov->iov_len < 1)
-				break;
-
-			if (!type) {
-				type = iov->iov_base;
-				/* check if code field is readable or not. */
-				if (iov->iov_len > 1)
-					code = type + 1;
-			} else if (!code)
-				code = iov->iov_base;
-
-			if (type && code) {
-				if (get_user(fl4->fl4_icmp_type, type) ||
-				    get_user(fl4->fl4_icmp_code, code))
-					return -EFAULT;
-				probed = 1;
-			}
-			break;
-		default:
-			probed = 1;
-			break;
-		}
-		if (probed)
-			break;
-	}
+	/* We only need the first two bytes. */
+	err = memcpy_fromiovecend((void *)&icmph, msg->msg_iov, 0, 2);
+	if (err)
+		return err;
+
+	fl4->fl4_icmp_type = icmph.type;
+	fl4->fl4_icmp_code = icmph.code;
+
 	return 0;
 }