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Date: Wed, 2 Sep 2009 17:33:12 +0200
Message-ID: <b5ddba180909020833w1739bd54t11fded8150007abc@mail.gmail.com>
Subject: Re: [PATCH 1/3] netfilter: xt_ipvs (netfilter matcher for IPVS)
From: Hannes Eder <heder@google.com>
To: Patrick McHardy <kaber@trash.net>
Cc: lvs-devel@vger.kernel.org, linux-kernel@vger.kernel.org,
       netdev@vger.kernel.org, netfilter-devel@vger.kernel.org,
       =?ISO-8859-1?Q?Fabien_Duch=EAne?= <mad_fab@skynet.be>,
       Jan Engelhardt <jengelh@medozas.de>,
       Jean-Luc Fortemaison <jl.fortemaison@uclouvain.be>,
       Julian Anastasov <ja@ssi.bg>, Julius Volz <julius.volz@gmail.com>,
       Laurent Grawet <laurent.grawet@uclouvain.be>,
       Simon Horman <horms@verge.net.au>, Wensong Zhang <wensong@linux-vs.org>
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On Wed, Sep 2, 2009 at 16:54, Patrick McHardy<kaber@trash.net> wrote:
> Hannes Eder wrote:
>> This implements the kernel-space side of the netfilter matcher
>> xt_ipvs.
>
> Looks mostly fine to me, just one question:
>
>> +bool ipvs_mt(const struct sk_buff *skb, const struct xt_match_param *par)
>> +{
>> + ? ? const struct xt_ipvs *data = par->matchinfo;
>> + ? ? const u_int8_t family = par->family;
>> + ? ? struct ip_vs_iphdr iph;
>> + ? ? struct ip_vs_protocol *pp;
>> + ? ? struct ip_vs_conn *cp;
>> + ? ? int af;
>> + ? ? bool match = true;
>> +
>> + ? ? if (data->bitmask == XT_IPVS_IPVS_PROPERTY) {
>> + ? ? ? ? ? ? match = skb->ipvs_property ^
>> + ? ? ? ? ? ? ? ? ? ? !!(data->invert & XT_IPVS_IPVS_PROPERTY);
>> + ? ? ? ? ? ? goto out;
>> + ? ? }
>> +
>> + ? ? /* other flags than XT_IPVS_IPVS_PROPERTY are set */
>> + ? ? if (!skb->ipvs_property) {
>> + ? ? ? ? ? ? match = false;
>> + ? ? ? ? ? ? goto out;
>> + ? ? }
>> +
>> + ? ? switch (skb->protocol) {
>> + ? ? case ?htons(ETH_P_IP):
>> + ? ? ? ? ? ? af = AF_INET;
>> + ? ? ? ? ? ? break;
>> +#ifdef CONFIG_IP_VS_IPV6
>> + ? ? case ?htons(ETH_P_IPV6):
>> + ? ? ? ? ? ? af = AF_INET6;
>> + ? ? ? ? ? ? break;
>> +#endif
>> + ? ? default:
>> + ? ? ? ? ? ? match = false;
>> + ? ? ? ? ? ? goto out;
>> + ? ? }
>
> In the NF_INET_LOCAL_OUT hook skb->protocol is invalid. So if you
> don't need this, it would make sense to restrict the match to the
> other hooks.
>
> Even easier would be to use par->family, which contains the address
> family and doesn't need any translation.

Nice, I'll use par->family.

So in theory I do not even need a check like the following in the beginning?

	if (family != NFPROTO_IPV4
#ifdef CONFIG_IP_VS_IPV6
	    && family != NFPROTO_IPV6
#endif
		) {
		match = false;
		goto out;
	}

Thanks,
-Hannes
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