linux-kernel - Re: [PATCH 1/2] rust: usb: add basic USB abstractions

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <DD0AP6DE36C8.V0537W5RGUIQ@kernel.org>
Date: Tue, 23 Sep 2025 17:46:33 +0200
From: "Danilo Krummrich" <dakr@...nel.org>
To: "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>
Cc: "Oliver Neukum" <oneukum@...e.com>, "Daniel Almeida"
 <daniel.almeida@...labora.com>, "Miguel Ojeda" <ojeda@...nel.org>, "Alex
 Gaynor" <alex.gaynor@...il.com>, "Boqun Feng" <boqun.feng@...il.com>, "Gary
 Guo" <gary@...yguo.net>, Björn Roy Baron
 <bjorn3_gh@...tonmail.com>, "Benno Lossin" <lossin@...nel.org>, "Andreas
 Hindborg" <a.hindborg@...nel.org>, "Alice Ryhl" <aliceryhl@...gle.com>,
 "Trevor Gross" <tmgross@...ch.edu>, <linux-kernel@...r.kernel.org>,
 <rust-for-linux@...r.kernel.org>, <linux-usb@...r.kernel.org>
Subject: Re: [PATCH 1/2] rust: usb: add basic USB abstractions

On Tue Sep 23, 2025 at 4:49 PM CEST, Greg Kroah-Hartman wrote:
> On Tue, Sep 23, 2025 at 04:42:11PM +0200, Danilo Krummrich wrote:
>> On 9/23/25 4:37 PM, Greg Kroah-Hartman wrote:
>> > Yes, you are right, it can be gotten that way.  But I can't wait to see
>> > how you wrap that C macro in rust :)
>> 
>> We can either create a Rust helper function for it, or just re-implement it; in
>> the end it boils down to just a container_of() on the parent device.
>
> Yes, and it preserves the "const" of the pointer going into the function
> call, can we do that in rust as well?

Yes, the Rust container_of!() macro should preserve that.

But despite that, I think it doesn't matter too much in this specific case.

Abstractions of C structures are usually contained within the kernel's Opaque<T>
type, which allows for interior mutability.

Actual mutability is controlled by the corresponding abstraction around the
Opaque<T>.

For instance, a struct device representation looks like this:

	 struct Device<Ctx: DeviceContext = Normal>(Opaque<bindings::device>, PhantomData<Ctx>);

In this case, we never give out a mutable reference to a Device, but rather
control mutability internally with the help of the device context.

For instance, if we have a &Device<Core>, we're guranteed that we're called from
a context where the device_lock() is guaranteed to be held, so we can allow for
some interior mutability.