From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Miroslav Benes <mbenes@suse.cz>
Cc: Joe Lawrence <joe.lawrence@redhat.com>,
Petr Mladek <pmladek@suse.com>,
jikos@kernel.org, linux-kernel@vger.kernel.org,
live-patching@vger.kernel.org
Subject: Re: [RFC PATCH 2/2] livepatch: Clear relocation targets on a module removal
Date: Thu, 5 Sep 2019 07:54:18 -0500 [thread overview]
Message-ID: <20190905125418.kleis5ackvhtn4hs@treble> (raw)
In-Reply-To: <alpine.LSU.2.21.1909051403530.25712@pobox.suse.cz>
On Thu, Sep 05, 2019 at 02:16:51PM +0200, Miroslav Benes wrote:
> > > > A full demo would require packaging up replacement .ko's with a livepatch, as
> > > > well as "blacklisting" those deprecated .kos, etc. But that's all I had time
> > > > to cook up last week before our holiday weekend here.
> > >
> > > Frankly, I'm not sure about this approach. I'm kind of torn. The current
> > > solution is far from ideal, but I'm not excited about the other options
> > > either. It seems like the choice is basically between "general but
> > > technically complicated fragile solution with nontrivial maintenance
> > > burden", or "something safer and maybe cleaner, but limiting for
> > > users/distros". Of course it depends on whether the limitation is even
> > > real and how big it is. Unfortunately we cannot quantify it much and that
> > > is probably why our opinions (in the email thread) differ.
> >
> > How would this option be "limiting for users/distros"? If the packaging
> > part of the solution is done correctly then I don't see how it would be
> > limiting.
>
> I'll try to explain my worries.
>
> Blacklisting first. Yes, I agree that it would make things a lot simpler,
> but I am afraid it would not fly at SUSE. Petr meanwhile explained
> elsewhere, but I don't think we can limit our customers that much. We
> perceive live patching as a product as much transparent as possible and as
> less intrusive as possible. One thing is to forbid to remove a module, the
> other is to forbid its loading.
>
> We could warn the admin. Something like "there is a fix for a module foo,
> which is not loaded currently. It will not be patched and the system will
> be still vulnerable if you load the module unless a new fixed version is
> provided."
No. We just distribute the new .ko with the livepatch. It should be
transparent to the user.
> Yes, we can distribute the new version of .ko with a livepatch. What is
> the reason for blacklisting then? I don't probably understand, but either
> a module is loaded and we can patch it (without late module patching), or
> it is not and we could replace .ko on disk.
I think the blacklisting is a failsafe to prevent the old module from
accidentally getting loaded after patching.
> Now, I don't think that replacing .ko on disk is a good idea. We've
> already discussed it. It would lead to a maintenance/packaging problem,
> because you never know which version of the module is loaded in the
> system. The state space grows rather rapidly there.
What exactly are your concerns?
Either the old version of the module is loaded, and it's livepatched; or
the new version of the module is loaded, and it's not livepatched.
Anyway that could be reported to the user somehow, e.g. report
srcversion in sysfs.
--
Josh
next prev parent reply other threads:[~2019-09-05 12:54 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-19 12:28 [RFC PATCH 0/2] livepatch: Clear relocation targets on a module removal Miroslav Benes
2019-07-19 12:28 ` [PATCH 1/2] livepatch: Nullify obj->mod in klp_module_coming()'s error path Miroslav Benes
2019-07-28 19:45 ` Josh Poimboeuf
2019-08-19 11:26 ` Petr Mladek
2019-07-19 12:28 ` [RFC PATCH 2/2] livepatch: Clear relocation targets on a module removal Miroslav Benes
2019-07-22 9:33 ` Petr Mladek
2019-08-14 12:33 ` Miroslav Benes
2019-07-28 20:04 ` Josh Poimboeuf
2019-08-14 11:06 ` Miroslav Benes
2019-08-14 15:12 ` Josh Poimboeuf
2019-08-16 9:46 ` Petr Mladek
2019-08-22 22:36 ` Josh Poimboeuf
2019-08-23 8:13 ` Petr Mladek
2019-08-26 14:54 ` Josh Poimboeuf
2019-08-27 15:05 ` Joe Lawrence
2019-08-27 15:37 ` Josh Poimboeuf
2019-09-02 16:13 ` Miroslav Benes
2019-09-02 17:05 ` Joe Lawrence
2019-09-03 13:02 ` Miroslav Benes
2019-09-04 8:49 ` Petr Mladek
2019-09-04 16:26 ` Joe Lawrence
2019-09-05 2:50 ` Josh Poimboeuf
2019-09-05 11:09 ` Petr Mladek
2019-09-05 11:19 ` Jiri Kosina
2019-09-05 13:23 ` Josh Poimboeuf
2019-09-05 13:31 ` Jiri Kosina
2019-09-05 13:42 ` Josh Poimboeuf
2019-09-05 11:39 ` Joe Lawrence
2019-09-05 13:08 ` Josh Poimboeuf
2019-09-05 13:15 ` Josh Poimboeuf
2019-09-05 13:52 ` Petr Mladek
2019-09-05 14:28 ` Josh Poimboeuf
2019-09-05 12:03 ` Miroslav Benes
2019-09-05 12:35 ` Josh Poimboeuf
2019-09-05 12:49 ` Miroslav Benes
2019-09-05 11:52 ` Miroslav Benes
2019-09-05 2:32 ` Josh Poimboeuf
2019-09-05 12:16 ` Miroslav Benes
2019-09-05 12:54 ` Josh Poimboeuf [this message]
2019-09-06 12:51 ` Miroslav Benes
2019-09-06 15:38 ` Joe Lawrence
2019-09-06 16:45 ` Josh Poimboeuf
2019-08-26 13:44 ` Nicolai Stange
2019-08-26 15:02 ` Josh Poimboeuf
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