linux-kernel - Re: [PATCH v3 3/5] samples: rust: Provide example using the new Rust MiscDevice abstraction

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: <2024120621-unlisted-unbalance-3220@gregkh>
Date: Fri, 6 Dec 2024 08:03:34 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Arnd Bergmann <arnd@...db.de>
Cc: Lee Jones <lee@...nel.org>, linux-kernel@...r.kernel.org,
	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>,
	rust-for-linux@...r.kernel.org
Subject: Re: [PATCH v3 3/5] samples: rust: Provide example using the new Rust
 MiscDevice abstraction

On Fri, Dec 06, 2024 at 07:52:46AM +0100, Arnd Bergmann wrote:
> On Fri, Dec 6, 2024, at 07:49, Greg KH wrote:
> > On Thu, Dec 05, 2024 at 04:25:20PM +0000, Lee Jones wrote:
> >> +
> >> +#[vtable]
> >> +impl MiscDevice for RustMiscDevice {
> >> +    type Ptr = KBox<Self>;
> >> +
> >> +    fn open() -> Result<KBox<Self>> {
> >> +        pr_info!("Opening Rust Misc Device Sample\n");
> >> +
> >> +        Ok(KBox::new(RustMiscDevice, GFP_KERNEL)?)
> >> +    }
> >> +
> >> +    fn ioctl(
> >> +        _device: <Self::Ptr as kernel::types::ForeignOwnable>::Borrowed<'_>,
> >> +        cmd: u32,
> >> +        _arg: usize,
> >> +    ) -> Result<isize> {
> >> +        pr_info!("IOCTLing Rust Misc Device Sample\n");
> >> +
> >> +        match cmd {
> >> +            RUST_MISC_DEV_HELLO => pr_info!("Hello from the Rust Misc Device\n"),
> >> +            _ => {
> >> +                pr_err!("IOCTL not recognised: {}\n", cmd);
> >> +                return Err(ENOIOCTLCMD);
> >
> > To quote errno.h:
> > 	These should never be seen by user programs
> >
> > The correct value here is ENOTTY.
> >
> > Yeah, fun stuff.  Not intuitive at all, sorry.
> 
> That should get handled by vfs_ioctl() converting the
> ENOIOCTLCMD to ENOTTY.

Ah, I always miss that, for some reason I thought that didn't happen
there, but happened in subsystems that did ENOIOCTLCMD for their
sub-ioctl handlers.  And yet it's always been that way, nevermind...

Anyway, I always recommend just using ENOTTY to be "safe", the usual way
people get this wrong is using EINVAL.

thanks,

greg k-h