[PATCH v10 4/8] rust: cred: add Rust abstraction for `struct cred`

[Paul Moore]

On Sun, Sep 15, 2024 at 10:31 AM Alice Ryhl <aliceryhl at google.com> wrote:
>
> From: Wedson Almeida Filho <wedsonaf at gmail.com>
>
> 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.
>
> This Rust abstraction makes the following assumptions about the C side:
> * `struct cred` is refcounted with `get_cred`/`put_cred`.
> * It's okay to transfer a `struct cred` across threads, that is, you do
>   not need to call `put_cred` on the same thread as where you called
>   `get_cred`.
> * The `euid` field of a `struct cred` never changes after
>   initialization.
> * The `f_cred` field of a `struct file` never changes after
>   initialization.
>
> Signed-off-by: Wedson Almeida Filho <wedsonaf at gmail.com>
> Co-developed-by: Alice Ryhl <aliceryhl at google.com>
> Reviewed-by: Trevor Gross <tmgross at umich.edu>
> Reviewed-by: Benno Lossin <benno.lossin at proton.me>
> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku at gmail.com>
> Reviewed-by: Gary Guo <gary at garyguo.net>
> Signed-off-by: Alice Ryhl <aliceryhl at google.com>
> ---
>  rust/bindings/bindings_helper.h |  1 +
>  rust/helpers/cred.c             | 13 +++++++
>  rust/helpers/helpers.c          |  1 +
>  rust/kernel/cred.rs             | 76 +++++++++++++++++++++++++++++++++++++++++
>  rust/kernel/fs/file.rs          | 13 +++++++
>  rust/kernel/lib.rs              |  1 +
>  6 files changed, 105 insertions(+)

Reviewed-by: Paul Moore <paul at paul-moore.com>

-- 
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