netdev - Re: [PATCH net-next v3 0/2] Add IP_LOCAL_PORT

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Message-ID: <CADVnQy=GCiBHDu0PYETh2nbaAeMtCwGgSG00wyJ8ezRgRBbABQ@mail.gmail.com>
Date:   Fri, 20 Jan 2023 11:44:47 -0500
From:   Neal Cardwell <ncardwell@...gle.com>
To:     Jakub Sitnicki <jakub@...udflare.com>
Cc:     netdev@...r.kernel.org, "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Kuniyuki Iwashima <kuniyu@...zon.com>, selinux@...r.kernel.org,
        Paul Moore <paul@...l-moore.com>,
        Stephen Smalley <stephen.smalley.work@...il.com>,
        Eric Paris <eparis@...isplace.org>, kernel-team@...udflare.com
Subject: Re: [PATCH net-next v3 0/2] Add IP_LOCAL_PORT_RANGE socket option

)On Fri, Jan 20, 2023 at 6:53 AM Jakub Sitnicki <jakub@...udflare.com> wrote:
>
> This patch set is a follow up to the "How to share IPv4 addresses by
> partitioning the port space" talk given at LPC 2022 [1].
>
> Please see patch #1 for the motivation & the use case description.
> Patch #2 adds tests exercising the new option in various scenarios.
>
> Documentation
> -------------
>
> Proposed update to the ip(7) man-page:
>
>        IP_LOCAL_PORT_RANGE (since Linux X.Y)
>               Set or get the per-socket default local port range. This
>               option  can  be used to clamp down the global local port
>               range, defined by the ip_local_port_range  /proc  inter‐
>               face described below, for a given socket.
>
>               The option takes an uint32_t value with the high 16 bits
>               set to the upper range bound, and the low 16 bits set to
>               the lower range bound. Range bounds are inclusive.

IMHO it would be nice for this text to document whether the port
numbers are in host order or network order, and perhaps whether "high"
and "low" here refer to host or network order. Key parts of the
sockets API express port numbers in network order, but this new API
seems to express port numbers in host order, so it seem worth (a)
deciding carefully, and (b) documenting explicitly in the man page
text (here in the cover letter) and commit message for the patch
(patch #1).

thanks,
neal