linux-kernel - Re: [PATCH v2 0/6] LSM: Replace secctx/len pairs with lsm

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Message-ID: <20241014212937.GA1100381@mail.hallyn.com>
Date: Mon, 14 Oct 2024 16:29:37 -0500
From: "Serge E. Hallyn" <serge@...lyn.com>
To: Casey Schaufler <casey@...aufler-ca.com>
Cc: paul@...l-moore.com, linux-security-module@...r.kernel.org,
	jmorris@...ei.org, serge@...lyn.com, keescook@...omium.org,
	john.johansen@...onical.com, penguin-kernel@...ove.sakura.ne.jp,
	stephen.smalley.work@...il.com, linux-kernel@...r.kernel.org,
	selinux@...r.kernel.org, mic@...ikod.net
Subject: Re: [PATCH v2 0/6] LSM: Replace secctx/len pairs with lsm_context

On Mon, Oct 14, 2024 at 08:14:44AM -0700, Casey Schaufler wrote:
> LSM: Replace secctx/len pairs with lsm_context
> 
> Several of the Linux Security Module (LSM) interfaces use a pair of
> pointers for transmitting security context data and data length. The
> data passed is refered to as a security context.  While all existing
> modules provide nul terminated strings, there is no requirement that
> they to so. Hence, the length is necessary.
> 
> Security contexts are provided by a number of interfaces. The interface
> security_release_secctx() is used when the caller is finished with the
> data. Each of the security modules that provide security contexts manages
> them differently. This was safe in the past, because only one security
> module that provides security contexts is allowed to be active. To allow
> multiple active modules that use security contexts it is necessary to
> identify which security module created a security context. Adding a third
> pointer to the interfaces for the LSM identification is not appealing.
> 
> A new structure, lsm_context, is created for use in these interfaces.
> It includes three members: the data pointer, the data length and
> the LSM ID of its creator. The interfaces that create contexts and
> security_release_secctx() now use a pointer to an lsm_context instead
> of a pointer pair.
> 
> The changes are mostly mechanical, and some scaffolding is used within
> the patch set to allow for smaller individual patches.

Hey Casey,

so this set is not bisectable.  Applying just patch 1 will no compile, right?
What is your plan for getting past that?  Squash some or all of them into one?
Or are you planning a wider reorg of the patches down the line, once the
basics of the end result are agreed upon?

-serge