linux-kernel - Re: [PATCH v10 1/5] rust: types: Add Ownable/Owned types

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] [day] [month] [year] [list]

Message-Id: <DAR7H7EY3ITC.1VEEK0VQCUGAJ@kernel.org>
Date: Fri, 20 Jun 2025 10:09:09 +0200
From: "Benno Lossin" <lossin@...nel.org>
To: "Oliver Mangold" <oliver.mangold@...me>
Cc: "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" <benno.lossin@...ton.me>,
 "Andreas Hindborg" <a.hindborg@...nel.org>, "Alice Ryhl"
 <aliceryhl@...gle.com>, "Trevor Gross" <tmgross@...ch.edu>, "Asahi Lina"
 <lina@...hilina.net>, <rust-for-linux@...r.kernel.org>,
 <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v10 1/5] rust: types: Add Ownable/Owned types

On Fri Jun 20, 2025 at 9:01 AM CEST, Oliver Mangold wrote:
> On 250618 2322, Benno Lossin wrote:
>> On Tue Jun 17, 2025 at 11:58 AM CEST, Oliver Mangold wrote:
>> > On 250514 1132, Benno Lossin wrote:
>> >> On Fri May 2, 2025 at 11:02 AM CEST, Oliver Mangold wrote:
>> >> > +///
>> >> > +/// # Safety
>> >> > +///
>> >> > +/// Implementers must ensure that:
>> >> > +/// - Any objects owned by Rust as [`Owned<T>`] stay alive while that owned reference exists (i.e.
>> >> > +///   until the [`release()`](Ownable::release) trait method is called).
>> >>
>> >> I don't immediately understand what this means. How about "Any value of
>> >> type `Self` needs to be stored as [`Owned<Self>`]."?
>> >
>> > Let me think. The safety requirements here talk about safety of
>> > implementing the trait.  But if you have a `Self` which is not wrapped, you
>> > still cannot create an `Owned<Self>` in safe code. It's different from an
>> > `AlwaysRefCounted`, where an `ARef<Self>` can be created from a `&Self`.
>> 
>> That might be true, but AFAIK this trait is designed to be used for
>> stuff that has a `create_foo` and `destroy_foo` function in C returning
>> and taking a raw pointer to `foo` respectively. So creating it on the
>> stack doesn't make sense.
>
> I didn't mean creating one on the stack, but keeping it in a raw pointer or
> `NonNull<T>`, not bothering to wrap in in an `Owned<T>`. But doesn't
> matter. In any case in v11 (which predates your answer), I moved this
> requirement to `Owned::from_raw()`, as, you asked below, which should be
> okay as that function is the only way to create an `Owned<T>`. But I can
> add the "needs to be stored as `Owned<Self>`" requirement, if you think it
> is important.

I'm not so sure, it depends on what we want `Owned<T>` to be. When I
take a look at v11, I might be able to figure it out.

---
Cheers,
Benno