linux-kernel - Re: [PATCH v15 01/11] LSM: Identify modules by more than name

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Message-ID: <dfdb82a8-85b2-4704-35b9-3ad901a179f1@I-love.SAKURA.ne.jp>
Date:   Sun, 24 Sep 2023 20:06:07 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Kees Cook <keescook@...omium.org>
Cc:     Casey Schaufler <casey@...aufler-ca.com>, paul@...l-moore.com,
        linux-security-module@...r.kernel.org, jmorris@...ei.org,
        serge@...lyn.com, john.johansen@...onical.com,
        stephen.smalley.work@...il.com, linux-kernel@...r.kernel.org,
        linux-api@...r.kernel.org, mic@...ikod.net,
        Dave Chinner <david@...morbit.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Jonathan Corbet <corbet@....net>
Subject: Re: [PATCH v15 01/11] LSM: Identify modules by more than name

Patch description says

  The LSM ID values are sequential, with the oldest module
  LSM_ID_CAPABILITY being the lowest value and the existing modules
  numbered in the order they were included in the main line kernel.
  This is an arbitrary convention for assigning the values, but
  none better presents itself. The value 0 is defined as being invalid.

and your non-sequential assignment

> But lsm_id::id is a u64 (not an enum!), so there is a HUGE space available.

violated it. include/uapi/linux/lsm.h is a userspace API file, where
we can't change this value after once defined.

You withdraw your "Reviewed-by" response unless "The LSM ID values are sequential"
and "must be approved by the LSM maintainers" are removed and "the LSM maintainers/community
shall never complain about what names and/or values are assigned" is added, don't you?

Quoting from https://lkml.kernel.org/r/4a6b6e2c-9872-4d4c-e42e-4ff0fb79f3ae@I-love.SAKURA.ne.jp :

  You are intentionally making life difficult for the out-of-tree LSMs, by
  requiring an LSM ID (and facilitating LSM ID collisions). No matter how
  priority of out-of-tree LSMs is low for you, what you are about to merge
  goes against the "developers try to avoid identifier collisions" effort.

  Introducing a numeric identifier is a good opportunity for permanently
  eliminating possibility of identifier collisions. But current usage of this
  numeric identifier is designed for facilitating possibility of identifier
  collisions.

Keeping how the HUGE space is used under control of the LSM community will be
better for both in-tree and out-of-tree LSM modules. I really can't understand
why you don't want to utilize this opportunity.