Commit f1fb08f6 authored by Vincent Bernat's avatar Vincent Bernat Committed by David S. Miller
Browse files

vxlan: fix ND proxy when skb doesn't have transport header offset 



When an incoming frame is tagged or when GRO is disabled, the skb
handled to vxlan_xmit() doesn't contain a valid transport header
offset. This makes ND proxying fail.

We combine two changes: replace use of skb_transport_offset() and ensure
the necessary amount of skb is linear just before using it:

 - In vxlan_xmit(), when determining if we have an ICMPv6 neighbor
   discovery packet, just check if it is an ICMPv6 packet and rely on
   neigh_reduce() to do more checks if this is the case. The use of
   pskb_may_pull() is replaced by skb_header_pointer() for just the IPv6
   header.

 - In neigh_reduce(), add pskb_may_pull() for IPv6 header and neighbor
   discovery message since this was removed from vxlan_xmit(). Replace
   skb_transport_header() with ipv6_hdr() + 1.

 - In vxlan_na_create(), replace first skb_transport_offset() with
   ipv6_hdr() + 1 and second with skb_network_offset() + sizeof(struct
   ipv6hdr). Additionally, ensure we pskb_may_pull() the whole skb as we
   need it to iterate over the options.

Signed-off-by: default avatarVincent Bernat <vincent@bernat.im>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d229d48d

drivers/net/vxlan.c

+15 −14
Original line number Diff line number Diff line
@@ -1515,7 +1515,7 @@ static struct sk_buff *vxlan_na_create(struct sk_buff *request, 
	int ns_olen;

	int i, len;



	if (dev == NULL)

	if (dev == NULL || !pskb_may_pull(request, request->len))

		return NULL;



	len = LL_RESERVED_SPACE(dev) + sizeof(struct ipv6hdr) +
@@ -1530,10 +1530,11 @@ static struct sk_buff *vxlan_na_create(struct sk_buff *request, 
	skb_push(reply, sizeof(struct ethhdr));

	skb_reset_mac_header(reply);



	ns = (struct nd_msg *)skb_transport_header(request);

	ns = (struct nd_msg *)(ipv6_hdr(request) + 1);



	daddr = eth_hdr(request)->h_source;

	ns_olen = request->len - skb_transport_offset(request) - sizeof(*ns);

	ns_olen = request->len - skb_network_offset(request) -

		sizeof(struct ipv6hdr) - sizeof(*ns);

	for (i = 0; i < ns_olen-1; i += (ns->opt[i+1]<<3)) {

		if (ns->opt[i] == ND_OPT_SOURCE_LL_ADDR) {

			daddr = ns->opt + i + sizeof(struct nd_opt_hdr);
@@ -1604,10 +1605,13 @@ static int neigh_reduce(struct net_device *dev, struct sk_buff *skb, __be32 vni) 
	if (!in6_dev)

		goto out;



	if (!pskb_may_pull(skb, sizeof(struct ipv6hdr) + sizeof(struct nd_msg)))

		goto out;



	iphdr = ipv6_hdr(skb);

	daddr = &iphdr->daddr;



	msg = (struct nd_msg *)skb_transport_header(skb);

	msg = (struct nd_msg *)(iphdr + 1);

	if (msg->icmph.icmp6_code != 0 ||

	    msg->icmph.icmp6_type != NDISC_NEIGHBOUR_SOLICITATION)

		goto out;
@@ -2242,15 +2246,12 @@ static netdev_tx_t vxlan_xmit(struct sk_buff *skb, struct net_device *dev) 
		if (ntohs(eth->h_proto) == ETH_P_ARP)

			return arp_reduce(dev, skb, vni);

#if IS_ENABLED(CONFIG_IPV6)

		else if (ntohs(eth->h_proto) == ETH_P_IPV6 &&

			 pskb_may_pull(skb, sizeof(struct ipv6hdr)

				       + sizeof(struct nd_msg)) &&

			 ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {

				struct nd_msg *msg;



				msg = (struct nd_msg *)skb_transport_header(skb);

				if (msg->icmph.icmp6_code == 0 &&

				    msg->icmph.icmp6_type == NDISC_NEIGHBOUR_SOLICITATION)

		else if (ntohs(eth->h_proto) == ETH_P_IPV6) {

			struct ipv6hdr *hdr, _hdr;

			if ((hdr = skb_header_pointer(skb,

						      skb_network_offset(skb),

						      sizeof(_hdr), &_hdr)) &&

			    hdr->nexthdr == IPPROTO_ICMPV6)

				return neigh_reduce(dev, skb, vni);

		}

#endif

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