From: Ingo Molnar <mingo@kernel.org>
To: Kees Cook <keescook@chromium.org>
Cc: Peter Zijlstra <peterz@infradead.org>,
Jeff Vander Stoep <jeffv@google.com>,
Ingo Molnar <mingo@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
LKML <linux-kernel@vger.kernel.org>,
Jonathan Corbet <corbet@lwn.net>,
"Eric W. Biederman" <ebiederm@xmission.com>
Subject: Re: [kernel-hardening] Re: [PATCH 1/2] security, perf: allow further restriction of perf_event_open
Date: Wed, 3 Aug 2016 10:28:31 +0200 [thread overview]
Message-ID: <20160803082830.GA3163@gmail.com> (raw)
In-Reply-To: <CAGXu5jJ+b4mWQ+RwPLo26di1qUwKT344GoN6xwzA1fw5Ke=ydA@mail.gmail.com>
* Kees Cook <keescook@chromium.org> wrote:
> > I see 0 up-sides of this approach and, as per the above, a whole bunch of very
> > serious downsides.
> >
> > A global (esp. default inhibited) knob is too coarse and limiting.
>
> I haven't suggested it be default inhibit in the upstream Kconfig. And
> having this knob already with the 0, 1, and 2 settings seems
> incomplete to me without this highest level of restriction that 3
> would provide. That seems rather arbitrary to me. :)
The default has no impact on the "it's too coarse and limiting" negative property
of this patch, which is the show-stopper aspect. Please fix that aspect instead of
trying to argue around it.
This isn't some narrow debugging mechanism we can turn on/off globally and forget
about, this is a wide scope performance measurement and event logging
infrastructure that is being utilized not just by developers but by apps and
runtimes as well.
> Let me take this another way instead. What would be a better way to provide a
> mechanism for system owners to disable perf without an LSM? (Since far fewer
> folks run with an enforcing "big" LSM: I'm seeking as wide a coverage as
> possible.)
Because in practice what will happen is that if the only option is to do something
drastic for sekjurity, IT departments will do it - while if there's a more
flexible mechanism that does not throw out the baby with the bath water that is
going to be used.
This is as if 20 years ago you had submitted a patch to the early Linux TCP/IP
networking code to be on/off via a global sysctl switch and told people that
"in developer mode you can have networking, talk to your admin".
We'd have told you: "this switch is too coarse and limiting, please implement
something better, like a list of routes which defines which IP ranges are
accessible, and a privileged range of listen sockets ports and some flexible
kernel side filtering mechanism to inhibit outgoing/incoming connections".
Global sysctls are way too coarse.
Thanks,
Ingo
next prev parent reply other threads:[~2016-08-03 8:28 UTC|newest]
Thread overview: 45+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-27 14:45 [kernel-hardening] [PATCH 1/2] security, perf: allow further restriction of perf_event_open Jeff Vander Stoep
2016-07-27 20:43 ` Kees Cook
2016-08-02 9:52 ` [kernel-hardening] " Peter Zijlstra
2016-08-02 13:04 ` Arnaldo Carvalho de Melo
2016-08-02 13:10 ` Daniel Micay
2016-08-02 13:16 ` Daniel Micay
2016-08-02 19:04 ` Kees Cook
2016-08-02 20:30 ` Peter Zijlstra
2016-08-02 20:51 ` Kees Cook
2016-08-02 21:06 ` Jeffrey Vander Stoep
2016-08-03 8:28 ` Ingo Molnar [this message]
2016-08-03 12:28 ` Daniel Micay
2016-08-03 12:53 ` Daniel Micay
2016-08-03 13:36 ` Peter Zijlstra
2016-08-03 14:41 ` Peter Zijlstra
2016-08-03 15:42 ` Schaufler, Casey
2016-08-03 17:25 ` Eric W. Biederman
2016-08-03 18:53 ` Kees Cook
2016-08-03 21:44 ` Peter Zijlstra
2016-08-04 2:50 ` Eric W. Biederman
2016-08-04 9:11 ` Peter Zijlstra
2016-08-04 15:13 ` Eric W. Biederman
2016-08-04 15:37 ` Peter Zijlstra
2016-08-03 19:36 ` Daniel Micay
2016-08-04 10:28 ` Mark Rutland
2016-08-04 13:45 ` Daniel Micay
2016-08-04 14:11 ` Peter Zijlstra
2016-08-04 15:44 ` Daniel Micay
2016-08-04 15:55 ` Peter Zijlstra
2016-08-04 16:10 ` Mark Rutland
2016-08-04 16:32 ` Daniel Micay
2016-08-04 17:09 ` Mark Rutland
2016-08-04 17:36 ` Daniel Micay
2016-08-02 21:16 ` Jeffrey Vander Stoep
2016-10-17 13:44 ` [kernel-hardening] " Mark Rutland
2016-10-17 14:54 ` Daniel Micay
2016-10-19 9:41 ` Mark Rutland
2016-10-19 15:16 ` Daniel Micay
2016-10-18 20:48 ` Kees Cook
2016-10-18 21:15 ` Daniel Micay
2016-10-19 9:56 ` Mark Rutland
2016-10-19 10:01 ` Peter Zijlstra
2016-10-19 10:26 ` Arnaldo Carvalho de Melo
2016-10-19 10:40 ` Peter Zijlstra
2016-10-19 15:39 ` Daniel Micay
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