From mboxrd@z Thu Jan 1 00:00:00 1970 From: Pablo Neira Ayuso Subject: [PATCH 03/29] netfilter: nf_dup4: remove redundant checksum recalculation Date: Mon, 5 Sep 2016 12:58:18 +0200 Message-ID: <1473073124-5015-4-git-send-email-pablo@netfilter.org> References: <1473073124-5015-1-git-send-email-pablo@netfilter.org> Cc: davem@davemloft.net, netdev@vger.kernel.org To: netfilter-devel@vger.kernel.org Return-path: In-Reply-To: <1473073124-5015-1-git-send-email-pablo@netfilter.org> Sender: netfilter-devel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org From: Liping Zhang 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 Signed-off-by: Pablo Neira Ayuso --- 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); -- 2.1.4