linux-kernel - Re: [PATCH 4/5] Make LSM Writable Hooks a command line option

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Date:   Tue, 6 Jun 2017 14:12:26 +0300
From:   Igor Stoppa <igor.stoppa@...wei.com>
To:     Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
        <casey@...aufler-ca.com>, <keescook@...omium.org>,
        <mhocko@...nel.org>, <jmorris@...ei.org>
CC:     <paul@...l-moore.com>, <sds@...ho.nsa.gov>, <hch@...radead.org>,
        <labbott@...hat.com>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>,
        <kernel-hardening@...ts.openwall.com>
Subject: Re: [PATCH 4/5] Make LSM Writable Hooks a command line option

On 06/06/17 13:54, Tetsuo Handa wrote:

[...]

> "Loading modules which are not compiled as built-in" is correct.
> My use case is to allow users to use LSM modules as loadable kernel
> modules which distributors do not compile as built-in.

Ok, so I suppose someone should eventually lock down the header, after
the additional modules are loaded.

Who decides when enough is enough, meaning that all the needed modules
are loaded?
Should I provide an interface to user-space? A sysfs entry?

[...]

> Unloading LSM modules is dangerous. Only SELinux allows unloading
> at the risk of triggering an oops. If we insert delay while removing
> list elements, we can easily observe oops due to free function being
> called without corresponding allocation function.

Ok. But even in this case, the sys proposal would still work.
It would just stay unused.


--
igor