netdev - Re: [PATCH net] gso: validate gso_type if SKB_GSO

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Message-ID: <CAF=yD-+zxwAuoZi2B1QXas933DXum-HUthF36m_NZzaoSTUG=A@mail.gmail.com>
Date:   Thu, 18 Jan 2018 16:22:57 -0500
From:   Willem de Bruijn <willemdebruijn.kernel@...il.com>
To:     Jason Wang <jasowang@...hat.com>
Cc:     Network Development <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Willem de Bruijn <willemb@...gle.com>,
        Vlad Yasevic <vyasevic@...hat.com>,
        Herbert Xu <herbert@...dor.apana.org.au>,
        Tom Herbert <tom@...bertland.com>
Subject: Re: [PATCH net] gso: validate gso_type if SKB_GSO_DODGY

> Aside from inet_gso_segment and ipv6_gso_segment, this only leaves the
> new nsh_gso_segment. Unlke mpls, it has its own gso_type, so
>
>         if (!skb_shinfo(skb)->gso_type & SKB_GSO_NSH)
>                 goto out;

This last point was incorrect. There is no such type for this protocol, so
we have to do the same as for MPLS. Either assume that it is robust
or be conservative and add

        if (skb_shinfo(skb)->gso_type & SKB_GSO_DODGY)
                goto out;

It looks correct on the surface and may already be relied upon, so I
suggest the first approach.