[PATCH v10 5/8] rust: security: add abstraction for secctx

[Paul Moore]

On Sun, Sep 15, 2024 at 10:31 AM Alice Ryhl <aliceryhl at google.com> wrote:
>
> Add an abstraction for viewing the string representation of a security
> context.
>
> This is needed by Rust Binder because it has a feature where a process
> can view the string representation of the security context for incoming
> transactions. The process can use that to authenticate incoming
> transactions, and since the feature is provided by the kernel, the
> process can trust that the security context is legitimate.
>
> This abstraction makes the following assumptions about the C side:
> * When a call to `security_secid_to_secctx` is successful, it returns a
>   pointer and length. The pointer references a byte string and is valid
>   for reading for that many bytes.
> * The string may be referenced until `security_release_secctx` is
>   called.
> * If CONFIG_SECURITY is set, then the three methods mentioned in
>   rust/helpers are available without a helper. (That is, they are not a
>   #define or `static inline`.)
>
> Reviewed-by: Benno Lossin <benno.lossin at proton.me>
> Reviewed-by: Martin Rodriguez Reboredo <yakoyoku at gmail.com>
> Reviewed-by: Trevor Gross <tmgross at umich.edu>
> 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/helpers.c          |  1 +
>  rust/helpers/security.c         | 20 +++++++++++
>  rust/kernel/cred.rs             |  8 +++++
>  rust/kernel/lib.rs              |  1 +
>  rust/kernel/security.rs         | 74 +++++++++++++++++++++++++++++++++++++++++
>  6 files changed, 105 insertions(+)

I doubt my ACK is strictly necessary here since the Rust bindings
aren't actually modifying anything in the LSM, but just in case ...

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

-- 
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