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From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Jeff Vander Stoep <jeffv@google.com>,
	kernel-hardening@lists.openwall.com, mingo@redhat.com,
	alexander.shishkin@linux.intel.com, linux-doc@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: [kernel-hardening] Re: [PATCH 1/2] security, perf: allow further restriction of perf_event_open
Date: Tue, 2 Aug 2016 10:04:57 -0300
Message-ID: <20160802130457.GD26514@kernel.org> (raw)
In-Reply-To: <20160802095243.GD6862@twins.programming.kicks-ass.net>

Em Tue, Aug 02, 2016 at 11:52:43AM +0200, Peter Zijlstra escreveu:
> On Wed, Jul 27, 2016 at 07:45:46AM -0700, Jeff Vander Stoep wrote:
> > When kernel.perf_event_paranoid is set to 3 (or greater), disallow
> > all access to performance events by users without CAP_SYS_ADMIN.

> > This new level of restriction is intended to reduce the attack
> > surface of the kernel. Perf is a valuable tool for developers but
> > is generally unnecessary and unused on production systems. Perf may
> > open up an attack vector to vulnerable device-specific drivers as
> > recently demonstrated in CVE-2016-0805, CVE-2016-0819,
> > CVE-2016-0843, CVE-2016-3768, and CVE-2016-3843.
 
> We have bugs we fix them, we don't kill complete infrastructure because
> of them.
 
> > This new level of
> > restriction allows for a safe default to be set on production systems
> > while leaving a simple means for developers to grant access [1].
 
> So the problem I have with this is that it will completely inhibit
> development of things like JITs that self-profile to re-compile
> frequently used code.

Or reimplement strace with sys_perf_event_open(), speeding it up greatly
by not using ptrace (see 'perf trace', one such attempt), combining it
with sys_bpf(), which can run unpriviledged as well, provides lots of
possibilities for efficient tooling that would be greatly stiffled by
such big hammer restrictions :-(
 
> I would much rather have an LSM hook where the security stuff can do
> more fine grained control of things. Allowing some apps perf usage while
> denying others.

- Arnaldo

  reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-27 14:45 [kernel-hardening] " 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 [this message]
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
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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