linux-kernel - Re: [PATCH v4 1/2] netfilter: Terminate rule eval if protocol=IPv6 and ipv6 module is disabled

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Message-ID: <20190903203531.GF13660@breakpoint.cc>
Date:   Tue, 3 Sep 2019 22:35:31 +0200
From:   Florian Westphal <fw@...len.de>
To:     Pablo Neira Ayuso <pablo@...filter.org>
Cc:     Florian Westphal <fw@...len.de>,
        Leonardo Bras <leonardo@...ux.ibm.com>,
        netfilter-devel@...r.kernel.org, coreteam@...filter.org,
        bridge@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Jozsef Kadlecsik <kadlec@...filter.org>,
        Roopa Prabhu <roopa@...ulusnetworks.com>,
        Nikolay Aleksandrov <nikolay@...ulusnetworks.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [PATCH v4 1/2] netfilter: Terminate rule eval if protocol=IPv6
 and ipv6 module is disabled

Pablo Neira Ayuso <pablo@...filter.org> wrote:
> On Tue, Sep 03, 2019 at 09:48:09PM +0200, Florian Westphal wrote:
> > We could do that from nft_do_chain_netdev().
> 
> Indeed, this is all about the netdev case.
> 
> Probably add something similar to nf_ip6_route() to deal with
> ip6_route_lookup() case? This is the one trigering the problem, right?

Yes, this particular problem is caused by ipv6 fib not being
initialized due to ipv6.disable=1.  I don't know if there are cases
other than FIB.

> BTW, how does nft_fib_ipv6 module kicks in if ipv6 module is not
> loaded? The symbol dependency would pull in the IPv6 module anyway.

ipv6.disabled=1 does load the ipv6 module, but its non-functional.