Re: [PATCH v6 8/8] fscrypt: make prepared keys record their type

[Eric Biggers <ebiggers@kernel.org>]

On Tue, Aug 08, 2023 at 01:08:08PM -0400, Sweet Tea Dorminy wrote:
> +/**
> + * enum fscrypt_prepared_key_type - records a prepared key's ownership
> + *
> + * @FSCRYPT_KEY_PER_INFO: this prepared key is allocated for a specific info
> + *		          and is never shared.
> + * @FSCRYPT_KEY_DIRECT_V1: this prepared key is embedded in a fscrypt_direct_key
> + *		           used in v1 direct key policies.
> + * @FSCRYPT_KEY_MASTER_KEY: this prepared key is a per-mode and policy key,
> + *			    part of a fscrypt_master_key, shared between all
> + *			    users of this master key having this mode and
> + *			    policy.
> + */
> +enum fscrypt_prepared_key_type {
> +	FSCRYPT_KEY_PER_INFO = 1,
> +	FSCRYPT_KEY_DIRECT_V1,
> +	FSCRYPT_KEY_MASTER_KEY,
> +} __packed;

FSCRYPT_KEY_MASTER_KEY seems misnamed, since it's not for master keys.  It's for
what the code elsewhere calls a per-mode key.  So maybe FSCRYPT_KEY_PER_MODE?

I think your intent was for the name to reflect the struct that the
fscrypt_prepared_key is embedded in.  I don't think that's obvious as-is.  If
you want to name it that way, it should be made super clear, like this:

    enum fscrypt_prepared_key_owner {
            FSCRYPT_KEY_OWNED_BY_INFO = 1,
            FSCRYPT_KEY_OWNED_BY_DIRECT_V1,
            FSCRYPT_KEY_OWNED_BY_MASTER_KEY,
    };

But, I think I'm leaning towards your proposal with
s/FSCRYPT_KEY_MASTER_KEY/FSCRYPT_KEY_PER_MODE/.

- Eric