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Date: Fri, 5 May 2017 09:18:46 -0700
From: Andy Lutomirski <>
To: Djalal Harouni <>
Cc: Kees Cook <>, Andy Lutomirski <>, 
	Linux Kernel Mailing List <>, Andrew Morton <>, 
	"Serge E. Hallyn" <>, 
	"" <>, 
	LSM List <>, 
	Linux API <>, Dongsu Park <>, 
	Casey Schaufler <>, James Morris <>, 
	Paul Moore <>, Tetsuo Handa <>, 
	Greg Kroah-Hartman <>, Jonathan Corbet <>, 
	Jessica Yu <>, Rusty Russell <>, 
	Arnaldo Carvalho de Melo <>, Mauro Carvalho Chehab <>, Ingo Molnar <>, 
	belakhdar abdeldjalil <>, Peter Zijlstra <>, 
	Linus Torvalds <>
Subject: Re: [PATCH v3 2/2] modules:capabilities: add a per-task modules
 autoload restriction

On Thu, May 4, 2017 at 6:07 AM, Djalal Harouni <> wrote:
> On Sat, Apr 22, 2017 at 2:17 PM, Djalal Harouni <> wrote:
>> On Sat, Apr 22, 2017 at 1:28 AM, Andy Lutomirski <> wrote:
> [...]
>>> My point is that all of these need some way to handle configuration
>>> and inheritance, and I don't think that a bunch of per-task prctls is
>>> the right way.  As just an example, saying that interactive users can
>>> autoload modules but other users can't, or that certain systemd
>>> services can, etc, might be nice.  Linus already complained that he
>>> (i.e. user "torvalds" or whatever) should be able to profile the
>>> kernel but that other uids should not be able to.
>> Neat, maybe this could already be achieved with this interface and
>> systemd-logind,  "ModulesAutoloadUsers=andy" in logind.conf where
>> "andy" is the only logged-in user able to trigger and autoload kernel
>> modules. However maybe we should not restrict too much other bits or
>> functionality of the other users, please let me will follow up later
>> on it.
>>> I personally like my implicit_rights idea, and it might be interesting
>>> to prototype it.
> Andy following on the idea of per user settings, I'm curious did you
> manage to make some advance on how to store the user settings ? the
> user database format is old and not extensible, there was cgmanager or
> other libcgroup but for resources, and no simple thing for such
> restrictions example: "RestrictLinuxModules=user" that will prevent
> such users from making/loading extra Linux features/modules that are
> not already available...

I figured that user code would figure it out somehow.  Text config file?

There is another odd way it could be configured: just leave the inodes
around in /dev/rights with appropriate permissions.  Some startup
script could re-instantiate them with the same permissions (via a
syscall that does that atomically).

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