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netfilter: ip6t_REJECT: skip checksum verification for outgoing ipv6 packets 

Don't verify checksum for outgoing packets because checksum calculation
may be done by the device.

Without this patch:
$ ip6tables -I OUTPUT -p tcp --dport 80 -j REJECT --reject-with tcp-reset
$ time telnet ipv6.google.com 80
Trying 2a00:1450:4010:c03::67...
telnet: Unable to connect to remote host: Connection timed out

real    0m7.201s
user    0m0.000s
sys     0m0.000s

With the patch applied:
$ ip6tables -I OUTPUT -p tcp --dport 80 -j REJECT --reject-with tcp-reset
$ time telnet ipv6.google.com 80
Trying 2a00:1450:4010:c03::67...
telnet: Unable to connect to remote host: Connection refused

real    0m0.085s
user    0m0.000s
sys     0m0.000s

Signed-off-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Stanislav Fomichev 2013-10-22 16:43:23 +04:00 committed by Pablo Neira Ayuso
parent 1a869205c7
commit f2020b27be
1 changed files with 3 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
net/ipv6/netfilter/ip6t_REJECT.c
View File

@ -39,7 +39,7 @@ MODULE_DESCRIPTION("Xtables: packet \"rejection\" target for IPv6");
MODULE_LICENSE("GPL");
/* Send RST reply */
static void send_reset(struct net *net, struct sk_buff *oldskb)
static void send_reset(struct net *net, struct sk_buff *oldskb, int hook)
{
struct sk_buff *nskb;
struct tcphdr otcph, *tcph;
@ -88,8 +88,7 @@ static void send_reset(struct net *net, struct sk_buff *oldskb)
}
/* Check checksum. */
if (csum_ipv6_magic(&oip6h->saddr, &oip6h->daddr, otcplen, IPPROTO_TCP,
skb_checksum(oldskb, tcphoff, otcplen, 0))) {
if (nf_ip6_checksum(oldskb, hook, tcphoff, IPPROTO_TCP)) {
pr_debug("TCP checksum is invalid\n");
return;
}
@ -227,7 +226,7 @@ reject_tg6(struct sk_buff *skb, const struct xt_action_param *par)
/* Do nothing */
break;
case IP6T_TCP_RESET:
send_reset(net, skb);
send_reset(net, skb, par->hooknum);
break;
default:
net_info_ratelimited("case %u not handled yet\n", reject->with);