netdev - RE: [PATCH bpf-next v2 07/11] bpf, sockmap: Return socket cookie on lookup from syscall

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Message-ID: <5e1a6ecbcc114_76782ace374ba5c0f9@john-XPS-13-9370.notmuch>
Date:   Sat, 11 Jan 2020 16:56:43 -0800
From:   John Fastabend <john.fastabend@...il.com>
To:     Jakub Sitnicki <jakub@...udflare.com>, bpf@...r.kernel.org
Cc:     netdev@...r.kernel.org, kernel-team@...udflare.com,
        Eric Dumazet <edumazet@...gle.com>,
        John Fastabend <john.fastabend@...il.com>,
        Lorenz Bauer <lmb@...udflare.com>,
        Martin KaFai Lau <kafai@...com>
Subject: RE: [PATCH bpf-next v2 07/11] bpf, sockmap: Return socket cookie on
 lookup from syscall

Jakub Sitnicki wrote:
> Tooling that populates the SOCKMAP with sockets from user-space needs a way
> to inspect its contents. Returning the struct sock * that SOCKMAP holds to
> user-space is neither safe nor useful. An approach established by
> REUSEPORT_SOCKARRAY is to return a socket cookie (a unique identifier)
> instead.
> 
> Since socket cookies are u64 values SOCKMAP needs to support such a value
> size for lookup to be possible. This requires special handling on update,
> though. Attempts to do a lookup on SOCKMAP holding u32 values will be met
> with ENOSPC error.
> 
> Signed-off-by: Jakub Sitnicki <jakub@...udflare.com>
> ---

Acked-by: John Fastabend <john.fastabend@...il.com>