From: Eric Dumazet <edumazet@xxxxxxxxxx>
In case MSS option is added in TCP options, skb length increases by 4.
IPv6 needs to update skb->csum if skb has CHECKSUM_COMPLETE,
otherwise kernel complains loudly in netdev_rx_csum_fault() with a
stack dump.
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
---
net/netfilter/xt_TCPMSS.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/net/netfilter/xt_TCPMSS.c b/net/netfilter/xt_TCPMSS.c
index b7c43de..e118397 100644
--- a/net/netfilter/xt_TCPMSS.c
+++ b/net/netfilter/xt_TCPMSS.c
@@ -228,7 +228,7 @@ tcpmss_tg6(struct sk_buff *skb, const struct xt_action_param *par)
{
struct ipv6hdr *ipv6h = ipv6_hdr(skb);
u8 nexthdr;
- __be16 frag_off;
+ __be16 frag_off, oldlen, newlen;
int tcphoff;
int ret;
@@ -244,7 +244,12 @@ tcpmss_tg6(struct sk_buff *skb, const struct xt_action_param *par)
return NF_DROP;
if (ret > 0) {
ipv6h = ipv6_hdr(skb);
- ipv6h->payload_len = htons(ntohs(ipv6h->payload_len) + ret);
+ oldlen = ipv6h->payload_len;
+ newlen = htons(ntohs(oldlen) + ret);
+ if (skb->ip_summed == CHECKSUM_COMPLETE)
+ skb->csum = csum_add(csum_sub(skb->csum, oldlen),
+ newlen);
+ ipv6h->payload_len = newlen;
}
return XT_CONTINUE;
}
--
2.1.4
--
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