Date: Wed, 5 Jun 2013 15:02:53 +0200 From: Peter Zijlstra <peterz@...radead.org> To: eranian@...gle.com, ak@...ux.intel.com, security@...nel.org, Marcus Meissner <meissner@...e.de>, oss-security@...ts.openwall.com Subject: Re: CVE Request: More perf security fixes On Wed, Jun 05, 2013 at 02:38:56PM +0200, Petr Matousek wrote: > On Wed, Jun 05, 2013 at 02:15:59PM +0200, Peter Zijlstra wrote: > > On Wed, Jun 05, 2013 at 02:10:54PM +0200, Petr Matousek wrote: > > > Hello, Peter. > > > > > > On Tue, Jun 04, 2013 at 05:53:16PM +0200, Marcus Meissner wrote: > > > > 1. Info leak (?) via PERF_SAMPLE_BRANCH_KERNEL > > > > > > > > https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=7cc23cd6c0c7d7f4bee057607e7ce01568925717 > > > > > > > > commit 7cc23cd6c0c7d7f4bee057607e7ce01568925717 > > > > Author: Peter Zijlstra <a.p.zijlstra@...llo.nl> > > > > Date: Fri May 3 14:11:25 2013 +0200 > > > > > > > > perf/x86/intel/lbr: Demand proper privileges for PERF_SAMPLE_BRANCH_KERNEL > > > > > > > > We should always have proper privileges when requesting kernel > > > > data. > > > > > > > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl> > > > > Cc: <stable@...nel.org> > > > > Cc: Andi Kleen <ak@...ux.intel.com> > > > > Cc: eranian@...gle.com > > > > Link: http://email@example.com > > > > [ Fix build error reported by fengguang.wu@...el.com, propagate error code back. ] > > > > Signed-off-by: Ingo Molnar <mingo@...nel.org> > > > > Link: http://firstname.lastname@example.org > > > > > > There is similar check in perf_copy_attr() which is called from > > > perf_event_open syscall -- > > > > > > /* kernel level capture: check permissions */ > > > if ((mask & PERF_SAMPLE_BRANCH_PERM_PLM) > > > && perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) > > > return -EACCES; > > > > > > It seems to me that it covers PERF_SAMPLE_BRANCH_KERNEL as well. Am I > > > missing something? > > > > > > > I overlooked it, also its slightly broken. See the discussion at: > > https://lkml.org/lkml/2013/5/21/166 > > Got it, thanks for the pointer. So it is safe to say there never was a > leak in this case (and thus no security issue worth CVE)? There was a leak, notice how Stephane's patch did a s/PERF_SAMPLE_BRANCH_PERM_PLM/PERF_SAMPLE_BRANCH_KERNEL/ but also places the check _after_ we propagate the event PLM levels in the case none were LBR specific.
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