Commit af84f9e4 authored by Florian Westphal's avatar Florian Westphal
Browse files

netfilter: nft_payload: rebuild vlan header on h_proto access 



nft can perform merging of adjacent payload requests.
This means that:

ether saddr 00:11 ... ether type 8021ad ...

is a single payload expression, for 8 bytes, starting at the
ethernet source offset.

Check that offset+length is fully within the source/destination mac
addersses.

This bug prevents 'ether type' from matching the correct h_proto in case
vlan tag got stripped.

Fixes: de6843be ("netfilter: nft_payload: rebuild vlan header when needed")
Reported-by: default avatarDavid Ward <david.ward@ll.mit.edu>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
parent 51e7a666

net/netfilter/nft_payload.c

+12 −1
Original line number Diff line number Diff line
@@ -154,6 +154,17 @@ int nft_payload_inner_offset(const struct nft_pktinfo *pkt) 
	return pkt->inneroff;

}



static bool nft_payload_need_vlan_copy(const struct nft_payload *priv)

{

	unsigned int len = priv->offset + priv->len;



	/* data past ether src/dst requested, copy needed */

	if (len > offsetof(struct ethhdr, h_proto))

		return true;



	return false;

}



void nft_payload_eval(const struct nft_expr *expr,

		      struct nft_regs *regs,

		      const struct nft_pktinfo *pkt)
@@ -172,7 +183,7 @@ void nft_payload_eval(const struct nft_expr *expr, 
			goto err;



		if (skb_vlan_tag_present(skb) &&

		    priv->offset >= offsetof(struct ethhdr, h_proto)) {

		    nft_payload_need_vlan_copy(priv)) {

			if (!nft_payload_copy_vlan(dest, skb,

						   priv->offset, priv->len))

				goto err;