From 28427f368f0e08d504ed06e74bc7cc79d6d06511 Mon Sep 17 00:00:00 2001 From: Xiao Liang Date: Fri, 25 Aug 2023 13:33:27 +0800 Subject: 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: 99d1712bc41c ("netfilter: exthdr: tcp option set support") Fixes: 7890cbea66e7 ("netfilter: exthdr: add support for tcp option removal") Cc: stable@vger.kernel.org Signed-off-by: Xiao Liang Signed-off-by: Pablo Neira Ayuso --- net/netfilter/nft_exthdr.c | 20 ++++++++------------ 1 file changed, 8 insertions(+), 12 deletions(-) (limited to 'net/netfilter/nft_exthdr.c') diff --git a/net/netfilter/nft_exthdr.c b/net/netfilter/nft_exthdr.c index 7f856ceb3a66..a9844eefedeb 100644 --- a/net/netfilter/nft_exthdr.c +++ b/net/netfilter/nft_exthdr.c @@ -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; -- cgit v1.2.3