From mboxrd@z Thu Jan 1 00:00:00 1970 Reply-To: kernel-hardening@lists.openwall.com Date: Wed, 19 Oct 2016 07:26:02 -0300 From: Arnaldo Carvalho de Melo Message-ID: <20161019102602.GA25522@kernel.org> References: <1469630746-32279-1-git-send-email-jeffv@google.com> <20161017134413.GK29095@leverpostej> <1476825301.4032.7.camel@gmail.com> <20161019100126.GI3102@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20161019100126.GI3102@twins.programming.kicks-ass.net> Subject: Re: [kernel-hardening] [PATCH 1/2] security, perf: allow further restriction of perf_event_open To: Peter Zijlstra Cc: Daniel Micay , kernel-hardening@lists.openwall.com, Mark Rutland , Ingo Molnar , Alexander Shishkin , "linux-doc@vger.kernel.org" , LKML , Jeff Vander Stoep List-ID: 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. - Arnaldo