linux-kernel - Re: [PATCH] Yama: remove needless CONFIG_SECURITY_YAMA

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Message-ID: <55AEB1F5.9000300@schaufler-ca.com>
Date:	Tue, 21 Jul 2015 13:56:21 -0700
From:	Casey Schaufler <casey@...aufler-ca.com>
To:	Josh Boyer <jwboyer@...oraproject.org>
Cc:	Kees Cook <keescook@...omium.org>,
	linux-security-module <linux-security-module@...r.kernel.org>,
	James Morris <james.l.morris@...cle.com>,
	linux-doc@...r.kernel.org,
	"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Yama: remove needless CONFIG_SECURITY_YAMA_STACKED

On 7/21/2015 1:09 PM, Josh Boyer wrote:
> On Tue, Jul 21, 2015 at 3:48 PM, Casey Schaufler <casey@...aufler-ca.com> wrote:
>> On 7/21/2015 12:09 PM, Kees Cook wrote:
>>> Now that minor LSMs can cleanly stack with major LSMs, remove the unneeded
>>> config for Yama to be made to explicitly stack. Just selecting the main
>>> Yama CONFIG will allow it to work, regardless of the major LSM. Since
>>> distros using Yama are already forcing it to stack, this is effectively
>>> a no-op change.
>> Today I can compile in all LSMs including Yama and pick the one I want.
>> If we made your change it would be impossible to build in Yama and not
>> use it. I suggest we hold off until after the security summit discussion
> This is true, but it's also true regardless of stacking.  If Yama had
> a CONFIG_SECURITY_YAMA_ENABLED (or whatever bikeshed color), then you
> could enable Yama and not use it, yes?  It would also allow people to
> default it as disabled, but then enable it at runtime via the
> ptrace_scope sysctl.

The way Kees proposed it you would *always* get Yama stacked with
your other module if you compile Yama in. Thus, If I compile in
SELinux and Yama I cannot run SELinux without Yama. Today, I can
compile SELinux and Yama in but run only SELinux. My suggestion is
to wait until we can specify the modules to use before we remove
the kconfig option that provides that facility today.

>
> josh
>

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