netdev - Re: [net-next v2] vxlan: fix ND proxy when skb doesn't have transport header offset

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Date:   Thu, 30 Mar 2017 08:41:51 +0200
From:   Vincent Bernat <vincent@...nat.im>
To:     Eric Dumazet <edumazet@...gle.com>
Cc:     Roopa Prabhu <roopa@...ulusnetworks.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jiri Benc <jbenc@...hat.com>, netdev@...r.kernel.org
Subject: Re: [net-next v2] vxlan: fix ND proxy when skb doesn't have transport header offset

 ❦ 29 mars 2017 22:47 +0200, Vincent Bernat <vincent@...nat.im> :

> Parsing of neighbor discovery options is done earlier to ignore the
> whole packet in case of a malformed option. Moreover, the assumption the
> skb was linear is removed and options are extracted with
> skb_header_pointer() as well. The check on the source link-layer address
> option is also more strict (for Ethernet, we expect the length field to
> be 1).

There is some parsing implemented in net/ipv6/ndisc.c, notably
ndisc_parse_options(). I don't know if this is a good idea to reuse
that: it may have the expectation that some IP processing has already
been done (for example, the IPv6 length has already been checked, the
SKB is expected to be linear).
-- 
Watch out for off-by-one errors.
            - The Elements of Programming Style (Kernighan & Plauger)