Commit 28427f36 authored by Xiao Liang's avatar Xiao Liang Committed by Pablo Neira Ayuso
Browse files

netfilter: nft_exthdr: Fix non-linear header modification 



Fix skb_ensure_writable() size. Don't use nft_tcp_header_pointer() to
make it explicit that pointers point to the packet (not local buffer).

Fixes: 99d1712b ("netfilter: exthdr: tcp option set support")
Fixes: 7890cbea ("netfilter: exthdr: add support for tcp option removal")
Cc: stable@vger.kernel.org
Signed-off-by: default avatarXiao Liang <shaw.leon@gmail.com>
Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
parent bd6c11bc

net/netfilter/nft_exthdr.c

+8 −12
Original line number Diff line number Diff line
@@ -238,7 +238,12 @@ static void nft_exthdr_tcp_set_eval(const struct nft_expr *expr, 
	if (!tcph)

		goto err;



	if (skb_ensure_writable(pkt->skb, nft_thoff(pkt) + tcphdr_len))

		goto err;



	tcph = (struct tcphdr *)(pkt->skb->data + nft_thoff(pkt));

	opt = (u8 *)tcph;



	for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {

		union {

			__be16 v16;
@@ -253,15 +258,6 @@ static void nft_exthdr_tcp_set_eval(const struct nft_expr *expr, 
		if (i + optl > tcphdr_len || priv->len + priv->offset > optl)

			goto err;



		if (skb_ensure_writable(pkt->skb,

					nft_thoff(pkt) + i + priv->len))

			goto err;



		tcph = nft_tcp_header_pointer(pkt, sizeof(buff), buff,

					      &tcphdr_len);

		if (!tcph)

			goto err;



		offset = i + priv->offset;



		switch (priv->len) {
@@ -325,9 +321,9 @@ static void nft_exthdr_tcp_strip_eval(const struct nft_expr *expr, 
	if (skb_ensure_writable(pkt->skb, nft_thoff(pkt) + tcphdr_len))

		goto drop;



	opt = (u8 *)nft_tcp_header_pointer(pkt, sizeof(buff), buff, &tcphdr_len);

	if (!opt)

		goto err;

	tcph = (struct tcphdr *)(pkt->skb->data + nft_thoff(pkt));

	opt = (u8 *)tcph;



	for (i = sizeof(*tcph); i < tcphdr_len - 1; i += optl) {

		unsigned int j;