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netfilter: nft_exthdr: Fix non-linear header modification

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commit 28427f368f upstream.

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: 99d1712bc4 ("netfilter: exthdr: tcp option set support")
Fixes: 7890cbea66 ("netfilter: exthdr: add support for tcp option removal")
Cc: stable@vger.kernel.org
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Xiao Liang 2023-08-25 13:33:27 +08:00 committed by Greg Kroah-Hartman
parent d59b6fc405
commit 93450ea57e
1 changed files with 8 additions and 12 deletions
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20
net/netfilter/nft_exthdr.c
View file

@ -237,7 +237,12 @@ 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;
@ -252,15 +257,6 @@ 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) {
@ -324,9 +320,9 @@ 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;