Re: [PATCH 0/5] Rust support for `struct iov_iter`

Benno Lossin
2025-03-12T02:16:53Z

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patch set, as it will probably be hopelessly out of date.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