Re: [PATCH v1 0/2] Add LSM access controls for io_uring_setup

[Paul Moore <paul@paul-moore.com>]

On Mon, Nov 7, 2022 at 3:58 PM Gil Cukierman <cukie@google.com> wrote:
>
> This patchset provides the changes required for controlling access to
> the io_uring_setup system call by LSMs. It does this by adding a new
> hook to io_uring. It also provides the SELinux implementation for a new
> permission, io_uring { setup }, using the new hook.
>
> This is important because existing io_uring hooks only support limiting
> the sharing of credentials and access to the sensitive uring_cmd file
> op. Users of LSMs may also want the ability to tightly control which
> callers can retrieve an io_uring capable fd from the kernel, which is
> needed for all subsequent io_uring operations.

It isn't immediately obvious to me why simply obtaining a io_uring fd
from io_uring_setup() would present a problem, as the security
relevant operations that are possible with that io_uring fd *should*
still be controlled by other LSM hooks.  Can you help me understand
what security issue you are trying to resolve with this control?

-- 
paul-moore.com