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Commit f7f8ed56 authored by Antonio Quartulli's avatar Antonio Quartulli Committed by Antonio Quartulli
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batman-adv: h_vlan_encapsulated_proto access refactoring 



In case of a VLAN tagged frame the ethhdr pointer is
moved forward by 4 bytes so that the offset of h_proto
in struct ethhdr matches the real
h_vlan_encapsulated_proto address in the skb. While this
trickery is correct it makes the code harder to understand
and may lead to bugs in case of re-use of ethhdr for other
purposes.

This patch introduces a proto variable to make things
cleaner and easier to understand.

Signed-off-by: default avatarAntonio Quartulli <ordex@autistici.org>
Signed-off-by: default avatarMarek Lindner <lindner_marek@yahoo.de>
parent 21026059

net/batman-adv/gateway_client.c

+12 −7
Original line number Diff line number Diff line
@@ -655,24 +655,29 @@ bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len) 
	struct iphdr *iphdr;

	struct ipv6hdr *ipv6hdr;

	struct udphdr *udphdr;

	struct vlan_ethhdr *vhdr;

	__be16 proto;



	/* check for ethernet header */

	if (!pskb_may_pull(skb, *header_len + ETH_HLEN))

		return false;

	ethhdr = (struct ethhdr *)skb->data;

	proto = ethhdr->h_proto;

	*header_len += ETH_HLEN;



	/* check for initial vlan header */

	if (ntohs(ethhdr->h_proto) == ETH_P_8021Q) {

	if (proto == htons(ETH_P_8021Q)) {

		if (!pskb_may_pull(skb, *header_len + VLAN_HLEN))

			return false;

		ethhdr = (struct ethhdr *)(skb->data + VLAN_HLEN);



		vhdr = (struct vlan_ethhdr *)skb->data;

		proto = vhdr->h_vlan_encapsulated_proto;

		*header_len += VLAN_HLEN;

	}



	/* check for ip header */

	switch (ntohs(ethhdr->h_proto)) {

	case ETH_P_IP:

	switch (proto) {

	case htons(ETH_P_IP):

		if (!pskb_may_pull(skb, *header_len + sizeof(*iphdr)))

			return false;

		iphdr = (struct iphdr *)(skb->data + *header_len);
@@ -683,7 +688,7 @@ bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len) 
			return false;



		break;

	case ETH_P_IPV6:

	case htons(ETH_P_IPV6):

		if (!pskb_may_pull(skb, *header_len + sizeof(*ipv6hdr)))

			return false;

		ipv6hdr = (struct ipv6hdr *)(skb->data + *header_len);
@@ -710,11 +715,11 @@ bool batadv_gw_is_dhcp_target(struct sk_buff *skb, unsigned int *header_len) 
	*header_len += sizeof(*udphdr);



	/* check for bootp port */

	if ((ntohs(ethhdr->h_proto) == ETH_P_IP) &&

	if ((proto == htons(ETH_P_IP)) &&

	    (ntohs(udphdr->dest) != 67))

		return false;



	if ((ntohs(ethhdr->h_proto) == ETH_P_IPV6) &&

	if ((proto == htons(ETH_P_IPV6)) &&

	    (ntohs(udphdr->dest) != 547))

		return false;