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From: Peter Zijlstra <peterz@infradead.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Micay <danielmicay@gmail.com>,
	kernel-hardening@lists.openwall.com,
	Mark Rutland <mark.rutland@arm.com>,
	Ingo Molnar <mingo@redhat.com>,
	Alexander Shishkin <alexander.shishkin@linux.intel.com>,
	"linux-doc@vger.kernel.org" <linux-doc@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Jeff Vander Stoep <jeffv@google.com>
Subject: Re: [kernel-hardening] [PATCH 1/2] security, perf: allow further restriction of perf_event_open
Date: Wed, 19 Oct 2016 12:40:56 +0200
Message-ID: <20161019104056.GK3102@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <20161019102602.GA25522@kernel.org>

On Wed, Oct 19, 2016 at 07:26:02AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Wed, Oct 19, 2016 at 12:01:26PM +0200, Peter Zijlstra escreveu:
> > On Tue, Oct 18, 2016 at 05:15:01PM -0400, Daniel Micay wrote:
> > > It's also worth noting that fine-grained control via a scoped mechanism
> > > would likely only be used to implement *more restrictions* on Android,
> > > not to make the feature less aggressive.
>  
> > > It's desirable for perf events to be disabled by default for non-root
> > > across the board on Android.
>  
> > Right, but this is Android. The knob seems to now also live in Debian
> > (and derived) distros. And there it is utter crap.
>  
> > It completely defeats having perf for a fairly large segment of
> > corporate developers who do not get to have root on their own machines
> > (which is stupid policy but whatever).
>  
> > It similarly defeats development of self profiling JITs and whatnot.
>  
> > A capability would allow people to run perf (or another sanctioned
> > binary), even though in general they cannot do sys_perf_event_open().
> 
> But self profiling JITs would be useful for non-developers, on Android
> (anywhere, really), and for that it would require being able to at
> least, well, self profile, using sys_perf_event_open() by a normal
> process, limited to profiling itself, no?
> 
> This not being possible, self profiling will use some other means, its
> like sys_perf_event_open() never existed for them.

Right, so with capabilities, we could grant the binary the capability to
use sys_perf_event_open().

That would still leave developers of said JIT in a tight spot, because
there'd be no way to set the capability on their freshly compiled
binary.

They'd have to be granted the capability to the user, using pam_cap.
Which would involve corp. IT doing something sensible, ergo, this'll
never happen :-(.

  reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-27 14:45 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
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 [this message]
2016-10-19 15:39           ` Daniel Micay

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