From: Changli Gao Date: Mon, 5 Jul 2010 08:39:17 +0000 (+0200) Subject: netfilter: ipt_REJECT: postpone the checksum calculation. X-Git-Url: http://drtracing.org/?a=commitdiff_plain;h=98b0e84aaaf2be6c40998d011c9db96ea6498e20;p=deliverable%2Flinux.git netfilter: ipt_REJECT: postpone the checksum calculation. postpone the checksum calculation, then if the output NIC supports checksum offloading, we can utlize it. And though the output NIC doesn't support checksum offloading, but we'll mangle this packet, this can free us from updating the checksum, as the checksum calculation occurs later. Signed-off-by: Changli Gao Signed-off-by: Patrick McHardy --- diff --git a/net/ipv4/netfilter/ipt_REJECT.c b/net/ipv4/netfilter/ipt_REJECT.c index f5f4a888e4ec..3d0e064bab54 100644 --- a/net/ipv4/netfilter/ipt_REJECT.c +++ b/net/ipv4/netfilter/ipt_REJECT.c @@ -95,10 +95,11 @@ static void send_reset(struct sk_buff *oldskb, int hook) } tcph->rst = 1; - tcph->check = tcp_v4_check(sizeof(struct tcphdr), - niph->saddr, niph->daddr, - csum_partial(tcph, - sizeof(struct tcphdr), 0)); + tcph->check = ~tcp_v4_check(sizeof(struct tcphdr), niph->saddr, + niph->daddr, 0); + nskb->ip_summed = CHECKSUM_PARTIAL; + nskb->csum_start = (unsigned char *)tcph - nskb->head; + nskb->csum_offset = offsetof(struct tcphdr, check); addr_type = RTN_UNSPEC; if (hook != NF_INET_FORWARD @@ -115,7 +116,6 @@ static void send_reset(struct sk_buff *oldskb, int hook) goto free_nskb; niph->ttl = dst_metric(skb_dst(nskb), RTAX_HOPLIMIT); - nskb->ip_summed = CHECKSUM_NONE; /* "Never happens" */ if (nskb->len > dst_mtu(skb_dst(nskb)))