linux-hardening - Re: [PATCH] fortify: Provide a memcpy trap door for sharp corners

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Message-ID: <20220512084226.id7jghqbadluze5k@LT-SAEEDM-5760.attlocal.net>
Date:   Thu, 12 May 2022 01:42:26 -0700
From:   Saeed Mahameed <saeedm@...dia.com>
To:     Jakub Kicinski <kuba@...nel.org>
Cc:     Kees Cook <keescook@...omium.org>,
        Leon Romanovsky <leon@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>,
        Paolo Abeni <pabeni@...hat.com>,
        Coco Li <lixiaoyan@...gle.com>,
        Tariq Toukan <tariqt@...dia.com>, netdev@...r.kernel.org,
        linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-rdma@...r.kernel.org
Subject: Re: [PATCH] fortify: Provide a memcpy trap door for sharp corners

On 11 May 09:24, Jakub Kicinski wrote:
>On Tue, 10 May 2022 19:53:01 -0700 Kees Cook wrote:
>> As we continue to narrow the scope of what the FORTIFY memcpy() will
>> accept and build alternative APIs that give the compiler appropriate
>> visibility into more complex memcpy scenarios, there is a need for
>> "unfortified" memcpy use in rare cases where combinations of compiler
>> behaviors, source code layout, etc, result in cases where the stricter
>> memcpy checks need to be bypassed until appropriate solutions can be
>> developed (i.e. fix compiler bugs, code refactoring, new API, etc). The
>> intention is for this to be used only if there's no other reasonable
>> solution, for its use to include a justification that can be used
>> to assess future solutions, and for it to be temporary.
>>
>> Example usage included, based on analysis and discussion from:
>> https://lore.kernel.org/netdev/CANn89iLS_2cshtuXPyNUGDPaic=sJiYfvTb_wNLgWrZRyBxZ_g@mail.gmail.com
>
>Saeed, ack for taking this in directly? Or do you prefer to take this
>plus Eric's last BIG TCP patch via your tree?

Please take both, I asked Eric a question on the BIG TCP patch, but I
won't block the series.

Thanks!