Re: [PATCH v3 1/1] security: Add CONFIG_LSM_AUTO to handle default LSM stack ordering

From: Mickaël Salaün
Date: Fri Nov 04 2022 - 12:30:33 EST



On 18/10/2022 21:31, Paul Moore wrote:
On Tue, Oct 18, 2022 at 1:55 AM Kees Cook <keescook@xxxxxxxxxxxx> wrote:
On Mon, Oct 17, 2022 at 09:45:21PM -0400, Paul Moore wrote:

[...]

We can have defaults, like we do know, but I'm in no hurry to remove
the ability to allow admins to change the ordering at boot time.

My concern is with new LSMs vs the build system. A system builder will
be prompted for a new CONFIG_SECURITY_SHINY, but won't be prompted
about making changes to CONFIG_LSM to include it.

I would argue that if an admin/builder doesn't understand what a shiny
new LSM does, they shouldn't be enabling that shiny new LSM. Adding
new, potentially restrictive, controls to your kernel build without a
basic understanding of those controls is a recipe for disaster and I
try to avoid recommending disaster as a planned course of action :)

It depends on what this shiny new LSMs do *by default*. In the case of Landlock, it do nothing unless a process does specific system calls (same as for most new kernel features: sysfs entries, syscall flags…). I guess this is the same for most LSMs.