On Sun, Sep 15, 2024 at 02:31:30PM +0000, 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. > > This Rust abstraction makes the following assumptions about the C side: > * `struct cred` is refcounted with `get_cred`/`put_cred`. Yes > * 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`. Yes > * The `euid` field of a `struct cred` never changes after > initialization. "after initialization", yes. The bprm cred during exec is special in that it gets updated (bprm_fill_uid) before it is installed into current via commit_creds() in begin_new_exec() (the point of no return for exec). > * The `f_cred` field of a `struct file` never changes after > initialization. Yes. > > Signed-off-by: Wedson Almeida Filho <wedsonaf@xxxxxxxxx> > Co-developed-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> > Reviewed-by: Trevor Gross <tmgross@xxxxxxxxx> > Reviewed-by: Benno Lossin <benno.lossin@xxxxxxxxx> > Reviewed-by: Martin Rodriguez Reboredo <yakoyoku@xxxxxxxxx> > Reviewed-by: Gary Guo <gary@xxxxxxxxxxx> > Signed-off-by: Alice Ryhl <aliceryhl@xxxxxxxxxx> Reviewed-by: Kees Cook <kees@xxxxxxxxxx> -- Kees Cook
