From: Liping Zhang <liping.zhang@xxxxxxxxxxxxxx>
IP header checksum will be recalculated at ip_local_out, so
there's no need to calculated it here, remove it. Also update
code comments to illustrate it, and delete the misleading
comments about checksum recalculation.
Signed-off-by: Liping Zhang <liping.zhang@xxxxxxxxxxxxxx>
---
net/ipv4/netfilter/nf_dup_ipv4.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/net/ipv4/netfilter/nf_dup_ipv4.c b/net/ipv4/netfilter/nf_dup_ipv4.c
index ceb1873..cf986e1 100644
--- a/net/ipv4/netfilter/nf_dup_ipv4.c
+++ b/net/ipv4/netfilter/nf_dup_ipv4.c
@@ -74,21 +74,19 @@ void nf_dup_ipv4(struct net *net, struct sk_buff *skb, unsigned int hooknum,
nf_conntrack_get(skb->nfct);
#endif
/*
- * If we are in PREROUTING/INPUT, the checksum must be recalculated
- * since the length could have changed as a result of defragmentation.
- *
- * We also decrease the TTL to mitigate potential loops between two
- * hosts.
+ * If we are in PREROUTING/INPUT, decrease the TTL to mitigate potential
+ * loops between two hosts.
*
* Set %IP_DF so that the original source is notified of a potentially
* decreased MTU on the clone route. IPv6 does this too.
+ *
+ * IP header checksum will be recalculated at ip_local_out.
*/
iph = ip_hdr(skb);
iph->frag_off |= htons(IP_DF);
if (hooknum == NF_INET_PRE_ROUTING ||
hooknum == NF_INET_LOCAL_IN)
--iph->ttl;
- ip_send_check(iph);
if (nf_dup_ipv4_route(net, skb, gw, oif)) {
__this_cpu_write(nf_skb_duplicated, true);
--
2.5.5
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