linux-kernel - Re: [PATCH 0/5] Rust support for `struct iov

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Message-ID: <D8DXCTL4756M.LQL5WA0TONAF@proton.me>
Date: Wed, 12 Mar 2025 02:16:43 +0000
From: Benno Lossin <benno.lossin@...ton.me>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Alice Ryhl <aliceryhl@...gle.com>
Cc: Alexander Viro <viro@...iv.linux.org.uk>, Arnd Bergmann <arnd@...db.de>, Miguel Ojeda <ojeda@...nel.org>, Boqun Feng <boqun.feng@...il.com>, Gary Guo <gary@...yguo.net>, Björn Roy Baron <bjorn3_gh@...tonmail.com>, Andreas Hindborg <a.hindborg@...nel.org>, Trevor Gross <tmgross@...ch.edu>, Danilo Krummrich <dakr@...nel.org>, Matthew Maurer <mmaurer@...gle.com>, Lee Jones <lee@...nel.org>, linux-kernel@...r.kernel.org, rust-for-linux@...r.kernel.org
Subject: Re: [PATCH 0/5] Rust support for `struct iov_iter`

On Tue Mar 11, 2025 at 3:37 PM CET, Greg Kroah-Hartman wrote:
> On Tue, Mar 11, 2025 at 02:25:11PM +0000, Alice Ryhl wrote:
>> This series adds support for the `struct iov_iter` type. This type
>> represents an IO buffer for reading or writing, and can be configured
>> for either direction of communication.
>> 
>> In Rust, we define separate types for reading and writing. This will
>> ensure that you cannot mix them up and e.g. call copy_from_iter in a
>> read_iter syscall.
>> 
>> To use the new abstractions, miscdevices are given new methods read_iter
>> and write_iter that can be used to implement the read/write syscalls on
>> a miscdevice. The miscdevice sample is updated to provide read/write
>> operations.
>
> Nice, this is good to have, but what's the odds of tieing in the
> "untrusted buffer" logic here so that all misc drivers HAVE to properly
> validate the data sent to them before they can touch it:
> 	https://lore.kernel.org/r/20240925205244.873020-1-benno.lossin@proton.me

I have started to work on that again, just needed to get through several
things in my backlog...

Are there any drivers or abstractions in mainline that I can use for
creating the interface? Or are those still out of tree? I don't think
that I can use tarfs for that as I did back when I started with this
patch set, as it will probably be hopelessly out of date.

---
Cheers,
Benno

> I'd like to force drivers to do this, otherwise it's just going to force
> us to audit all paths from userspace->kernel that happen.
>
> thanks,
>
> greg k-h