Re: [PATCH v3 1/2] bpf: Add bpf_verify_signature() helper

[Alexei Starovoitov]

On Fri, Jun 10, 2022 at 6:59 AM Roberto Sassu <roberto.sassu@xxxxxxxxxx> wrote:
> +       keyring = (keyring_id == U16_MAX) ?
> +                 cred->session_keyring : (struct key *)keyring_id;

This is too limiting.
bpf prog should be able to do what *key syscalls can do.
By doing lookup_user_key(id) -> keyring.
Maybe it's ok to have a special reserved id that does
cred->sessions_keyring as a shortcut, but that's an optimization.