Received-SPF: pass (google.com: domain of linux-kernel+bounces-146580-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Precedence: bulk
MIME-Version: 1.0
References: <20240415-alice-mm-v5-0-6f55e4d8ef51@google.com>
 <20240415-alice-mm-v5-2-6f55e4d8ef51@google.com> <202404151605.6EFC791E@keescook>
In-Reply-To: <202404151605.6EFC791E@keescook>
From: Alice Ryhl <aliceryhl@google.com>
Date: Tue, 16 Apr 2024 11:57:03 +0200
Message-ID: <CAH5fLgg1UiU0b-1Wewz9Wm_V_G44G+TUb4L1beQF7mkAcCXKfg@mail.gmail.com>
Subject: Re: [PATCH v5 2/4] uaccess: always export _copy_[from|to]_user with CONFIG_RUST
To: Kees Cook <keescook@chromium.org>
Cc: Miguel Ojeda <ojeda@kernel.org>, Matthew Wilcox <willy@infradead.org>, 
	Al Viro <viro@zeniv.linux.org.uk>, Andrew Morton <akpm@linux-foundation.org>, 
	Alex Gaynor <alex.gaynor@gmail.com>, Wedson Almeida Filho <wedsonaf@gmail.com>, 
	Boqun Feng <boqun.feng@gmail.com>, Gary Guo <gary@garyguo.net>, 
	=?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= <bjorn3_gh@protonmail.com>, 
	Benno Lossin <benno.lossin@proton.me>, Andreas Hindborg <a.hindborg@samsung.com>, 
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>, =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= <arve@android.com>, 
	Todd Kjos <tkjos@android.com>, Martijn Coenen <maco@android.com>, 
	Joel Fernandes <joel@joelfernandes.org>, Carlos Llamas <cmllamas@google.com>, 
	Suren Baghdasaryan <surenb@google.com>, Arnd Bergmann <arnd@arndb.de>, linux-mm@kvack.org, 
	linux-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, 
	Christian Brauner <brauner@kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable

On Tue, Apr 16, 2024 at 1:05=E2=80=AFAM Kees Cook <keescook@chromium.org> w=
rote:
>
> On Mon, Apr 15, 2024 at 07:13:54AM +0000, Alice Ryhl wrote:
> > From: Arnd Bergmann <arnd@arndb.de>
> >
> > Rust code needs to be able to access _copy_from_user and _copy_to_user
> > so that it can skip the check_copy_size check in cases where the length
> > is known at compile-time, mirroring the logic for when C code will skip
> > check_copy_size. To do this, we ensure that exported versions of these
> > methods are available when CONFIG_RUST is enabled.
> >
> > Alice has verified that this patch passes the CONFIG_TEST_USER_COPY tes=
t
> > on x86 using the Android cuttlefish emulator.
> >
> > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
>
> Thanks for the updates and the comment on testing. :)
>
> Reviewed-by: Kees Cook <keescook@chromium.org>

Thanks for taking a look :)

Alice