netdev - Re: [PATCH bpf-next] bpf: fix memory leak in bpf_lwt_xmit

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Message-ID: <04fdb303-ceee-07b5-be56-89b63dca28f0@gmail.com>
Date:   Fri, 1 Mar 2019 19:27:19 -0700
From:   David Ahern <dsahern@...il.com>
To:     Peter Oskolkov <posk@...gle.com>
Cc:     Peter Oskolkov <posk@...k.io>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        netdev <netdev@...r.kernel.org>,
        Willem de Bruijn <willemb@...gle.com>
Subject: Re: [PATCH bpf-next] bpf: fix memory leak in bpf_lwt_xmit_reroute

On 2/28/19 10:57 AM, Peter Oskolkov wrote:
> David: I'm not sure how to test GSO (I assume we are talking about GSO
> here) in
> the selftest: the encapping code sets SKB_GSO_DODGY flag, and veth does
> not support
> dodginess: "tx-gso-robust: off [fixed]".
> 
> If the "dodgy" flag is not set, then gso validation in dev.c passes, and
> large GSO packets
> happily go through; if the "dodgy" flag is set, "dodgy" GSO packets are
> rejected, TCP does
> segmentation, and non-GSO packets happily go through (with an mtu tweak
> to the LWT tunnel).
> 
> So I see three options:
> - add a sysctl to _not_ set SKB_GSO_DODGY flag in lwt_bpf.c =>
> handle_gso_type();
> - change veth to accept "dodgy" GSO packets
> - test the code "as is", meaning that GSO will be tried and disabled by
> TCP stack
> 
> Which approach would you prefer?
> 

definitely not a sysctl.

After that, I don't have a suggestion for GSO at the moment.