netdev - Re: recvfrom/recvmsg performance and CONFIG_HARDENED

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Fri, 6 Dec 2019 08:19:03 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     Paolo Abeni <pabeni@...hat.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        David Laight <David.Laight@...LAB.COM>,
        network dev <netdev@...r.kernel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: recvfrom/recvmsg performance and CONFIG_HARDENED_USERCOPY



On 12/6/19 8:09 AM, Paolo Abeni wrote:

> Oh, nice! I though the compiler was smart enough to avoid the indirect
> call with the current code, but it looks like that least gcc 9.2.1 is
> not.
> 
> Thanks for pointing that out!
> 
> In this specific scenario I think the code you propose above is better
> than INDIRECT_CALL.
> 
> Would you submit the patch formally?

Certainly, although I am not sure this will be enough to close
the gap between recvmsg() and recvfrom() :)

Also I was wondering if a likely() or unlikely() clause would
make sense.

This could prevent an over zealous compiler optimizer
to put back the indirect call that we tried to avoid.