netdev - Re: [PATCH 1/3] netfilter: xt_ipvs (netfilter matcher for IPVS)

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Message-ID: <b5ddba180909020833w1739bd54t11fded8150007abc@mail.gmail.com>
Date:	Wed, 2 Sep 2009 17:33:12 +0200
From:	Hannes Eder <heder@...gle.com>
To:	Patrick McHardy <kaber@...sh.net>
Cc:	lvs-devel@...r.kernel.org, linux-kernel@...r.kernel.org,
	netdev@...r.kernel.org, netfilter-devel@...r.kernel.org,
	Fabien Duchêne <mad_fab@...net.be>,
	Jan Engelhardt <jengelh@...ozas.de>,
	Jean-Luc Fortemaison <jl.fortemaison@...ouvain.be>,
	Julian Anastasov <ja@....bg>,
	Julius Volz <julius.volz@...il.com>,
	Laurent Grawet <laurent.grawet@...ouvain.be>,
	Simon Horman <horms@...ge.net.au>,
	Wensong Zhang <wensong@...ux-vs.org>
Subject: Re: [PATCH 1/3] netfilter: xt_ipvs (netfilter matcher for IPVS)

On Wed, Sep 2, 2009 at 16:54, Patrick McHardy<kaber@...sh.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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