netdev - Re: Source address fib invalidation on IPv6

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Message-Id: <1478998272.2299343.785875225.19237693@webmail.messagingengine.com>
Date:   Sun, 13 Nov 2016 01:51:12 +0100
From:   Hannes Frederic Sowa <hannes@...essinduktion.org>
To:     "Jason A. Donenfeld" <Jason@...c4.com>,
        David Ahern <dsa@...ulusnetworks.com>
Cc:     Netdev <netdev@...r.kernel.org>,
        WireGuard mailing list <wireguard@...ts.zx2c4.com>,
        LKML <linux-kernel@...r.kernel.org>,
        YOSHIFUJI Hideaki <hideaki.yoshifuji@...aclelinux.com>
Subject: Re: Source address fib invalidation on IPv6

On Sun, Nov 13, 2016, at 01:43, Jason A. Donenfeld wrote:
> On Sat, Nov 12, 2016 at 8:08 PM, Jason A. Donenfeld <Jason@...c4.com>
> wrote:
> >> Gotcha. I don't see any checks that the saddr is valid similar to what IPv4 does.
> >>
> >> I think the right place to add a check is in ip6_dst_lookup_tail():
> >>     if (!ipv6_addr_any(&fl6->saddr)) {
> >>         // saddr is valid for L3 domain
> >>     }
> >
> > Right. It should probably do the check here, and return
> > ERR_PTR(-EINVAL), the same as the v4 version, so that ret codes can be
> > checked consistently.
> >
> > Thanks for looking into this. If you're backed up and would like me to
> > submit a patch, just let me know, and I'll give it my best shot.
> 
> In perusing through the v6 FIB code, I don't even see an analog of
> __ip_dev_find... Hm?

You probably need some combination of ipv6_chk_addr and/or
ipv6_check_addr_and_flags (where dev can also be NULL). Be careful if a
IFA_HOST or IFA_LINK address switches from one interface to another.

Bye,
Hannes