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Date: Mon, 15 Apr 2024 16:05:17 -0700
From: Kees Cook <keescook@chromium.org>
To: Alice Ryhl <aliceryhl@google.com>
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>,
	=?iso-8859-1?Q?Bj=F6rn?= Roy Baron <bjorn3_gh@protonmail.com>,
	Benno Lossin <benno.lossin@proton.me>,
	Andreas Hindborg <a.hindborg@samsung.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Arve =?iso-8859-1?B?SGr4bm5lduVn?= <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>
Subject: Re: [PATCH v5 2/4] uaccess: always export _copy_[from|to]_user with
 CONFIG_RUST
Message-ID: <202404151605.6EFC791E@keescook>
References: <20240415-alice-mm-v5-0-6f55e4d8ef51@google.com>
 <20240415-alice-mm-v5-2-6f55e4d8ef51@google.com>
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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 test
> 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>

-- 
Kees Cook