Re: [PATCH v4 4/9] rust: cred: add Rust abstraction for `struct cred`

[Alice Ryhl]

On Thu, Feb 8, 2024 at 1:35 AM Martin Rodriguez Reboredo
<yakoyoku@xxxxxxxxx> wrote:
>
> On 2/2/24 07:55, Alice Ryhl wrote:
> > From: Wedson Almeida Filho <wedsonaf@xxxxxxxxx>
> >
> > Add a wrapper around `struct cred` called `Credential`, and provide
> > functionality to get the `Credential` associated with a `File`.
> >
> > Rust Binder must check the credentials of processes when they attempt to
> > perform various operations, and these checks usually take a
> > `&Credential` as parameter. The security_binder_set_context_mgr function
> > would be one example. This patch is necessary to access these security_*
> > methods from Rust.
> >
> > Signed-off-by: Wedson Almeida Filho <wedsonaf@xxxxxxxxx>
> > Co-developed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> > Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx>
> > ---
> > [...]
> > +    /// Returns the credentials of the task that originally opened the file.
> > +    pub fn cred(&self) -> &Credential {
> > +        // SAFETY: It's okay to read the `f_cred` field without synchronization because `f_cred` is
> > +        // never changed after initialization of the file.
> > +        let ptr = unsafe { (*self.as_ptr()).f_cred };
>
>  From what I can see `file.f_cred` is valid from the moment `file` was
> initialized, worth to notice too IMO.

That's what it says?

Alice