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

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Message-ID: <20220511092417.3c1c60d9@kernel.org>
Date:   Wed, 11 May 2022 09:24:17 -0700
From:   Jakub Kicinski <kuba@...nel.org>
To:     Kees Cook <keescook@...omium.org>,
        Saeed Mahameed <saeedm@...dia.com>,
        Leon Romanovsky <leon@...nel.org>
Cc:     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 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?