* [PATCH] netfilter: seqadj: check seq offset before update
@ 2021-12-24 2:37 zhang kai
2022-01-06 21:53 ` Pablo Neira Ayuso
0 siblings, 1 reply; 2+ messages in thread
From: zhang kai @ 2021-12-24 2:37 UTC (permalink / raw)
To: pablo, kadlec, fw, davem, kuba, netfilter-devel, coreteam,
netdev, linux-kernel
Cc: zhang kai
if seq/ack offset is zero, don't update
Signed-off-by: zhang kai <zhangkaiheb@126.com>
---
net/netfilter/nf_conntrack_seqadj.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/net/netfilter/nf_conntrack_seqadj.c b/net/netfilter/nf_conntrack_seqadj.c
index 3066449f8bd8..d35e272a2e36 100644
--- a/net/netfilter/nf_conntrack_seqadj.c
+++ b/net/netfilter/nf_conntrack_seqadj.c
@@ -186,11 +186,13 @@ int nf_ct_seq_adjust(struct sk_buff *skb,
else
seqoff = this_way->offset_before;
- newseq = htonl(ntohl(tcph->seq) + seqoff);
- inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, false);
- pr_debug("Adjusting sequence number from %u->%u\n",
- ntohl(tcph->seq), ntohl(newseq));
- tcph->seq = newseq;
+ if (seqoff) {
+ newseq = htonl(ntohl(tcph->seq) + seqoff);
+ inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, false);
+ pr_debug("Adjusting sequence number from %u->%u\n",
+ ntohl(tcph->seq), ntohl(newseq));
+ tcph->seq = newseq;
+ }
if (!tcph->ack)
goto out;
@@ -201,6 +203,9 @@ int nf_ct_seq_adjust(struct sk_buff *skb,
else
ackoff = other_way->offset_before;
+ if (!ackoff)
+ goto out;
+
newack = htonl(ntohl(tcph->ack_seq) - ackoff);
inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack,
false);
--
2.17.1
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] netfilter: seqadj: check seq offset before update
2021-12-24 2:37 [PATCH] netfilter: seqadj: check seq offset before update zhang kai
@ 2022-01-06 21:53 ` Pablo Neira Ayuso
0 siblings, 0 replies; 2+ messages in thread
From: Pablo Neira Ayuso @ 2022-01-06 21:53 UTC (permalink / raw)
To: zhang kai
Cc: kadlec, fw, davem, kuba, netfilter-devel, coreteam, netdev, linux-kernel
On Fri, Dec 24, 2021 at 10:37:13AM +0800, zhang kai wrote:
> if seq/ack offset is zero, don't update
Please, provide more details: explain the scenario that triggers and
seq/ack offset adjustment of zero, describe the scenario that triggers
the bug, etc.
> Signed-off-by: zhang kai <zhangkaiheb@126.com>
> ---
> net/netfilter/nf_conntrack_seqadj.c | 15 ++++++++++-----
> 1 file changed, 10 insertions(+), 5 deletions(-)
>
> diff --git a/net/netfilter/nf_conntrack_seqadj.c b/net/netfilter/nf_conntrack_seqadj.c
> index 3066449f8bd8..d35e272a2e36 100644
> --- a/net/netfilter/nf_conntrack_seqadj.c
> +++ b/net/netfilter/nf_conntrack_seqadj.c
> @@ -186,11 +186,13 @@ int nf_ct_seq_adjust(struct sk_buff *skb,
> else
> seqoff = this_way->offset_before;
>
> - newseq = htonl(ntohl(tcph->seq) + seqoff);
> - inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, false);
> - pr_debug("Adjusting sequence number from %u->%u\n",
> - ntohl(tcph->seq), ntohl(newseq));
> - tcph->seq = newseq;
> + if (seqoff) {
> + newseq = htonl(ntohl(tcph->seq) + seqoff);
> + inet_proto_csum_replace4(&tcph->check, skb, tcph->seq, newseq, false);
> + pr_debug("Adjusting sequence number from %u->%u\n",
> + ntohl(tcph->seq), ntohl(newseq));
> + tcph->seq = newseq;
> + }
>
> if (!tcph->ack)
> goto out;
> @@ -201,6 +203,9 @@ int nf_ct_seq_adjust(struct sk_buff *skb,
> else
> ackoff = other_way->offset_before;
>
> + if (!ackoff)
> + goto out;
> +
> newack = htonl(ntohl(tcph->ack_seq) - ackoff);
> inet_proto_csum_replace4(&tcph->check, skb, tcph->ack_seq, newack,
> false);
> --
> 2.17.1
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2021-12-24 2:37 [PATCH] netfilter: seqadj: check seq offset before update zhang kai
2022-01-06 21:53 ` Pablo Neira Ayuso
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