lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
Open Source and information security mailing list archives
| ||
|
Date: Wed, 15 May 2013 16:30:19 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Stephane Eranian <eranian@...gle.com> Cc: Ingo Molnar <mingo@...nel.org>, LKML <linux-kernel@...r.kernel.org>, "ak@...ux.intel.com" <ak@...ux.intel.com> Subject: Re: [PATCH 3/3] perf, x86, lbr: Demand proper privileges for PERF_SAMPLE_BRANCH_KERNEL On Wed, May 15, 2013 at 03:37:22PM +0200, Stephane Eranian wrote: > On Fri, May 3, 2013 at 2:11 PM, Peter Zijlstra <a.p.zijlstra@...llo.nl> wrote: > > We should always have proper privileges when requesting kernel data. > > > > Cc: Andi Kleen <ak@...ux.intel.com> > > Cc: eranian@...gle.com > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl> > > Link: http://lkml.kernel.org/n/tip-v0x9ky3ahzr6nm3c6ilwrili@git.kernel.org > > --- > > arch/x86/kernel/cpu/perf_event_intel_lbr.c | 5 ++++- > > 1 file changed, 4 insertions(+), 1 deletion(-) > > > > --- a/arch/x86/kernel/cpu/perf_event_intel_lbr.c > > +++ b/arch/x86/kernel/cpu/perf_event_intel_lbr.c > > @@ -318,8 +318,11 @@ static void intel_pmu_setup_sw_lbr_filte > > if (br_type & PERF_SAMPLE_BRANCH_USER) > > mask |= X86_BR_USER; > > > > - if (br_type & PERF_SAMPLE_BRANCH_KERNEL) > > + if (br_type & PERF_SAMPLE_BRANCH_KERNEL) { > > + if (perf_paranoid_kernel() && !capable(CAP_SYS_ADMIN)) > > + return -EACCES; > > mask |= X86_BR_KERNEL; > > + } > > > This will prevent regular users from capturing kernel -> kernel branches. > But it won't prevent users from getting kernel -> user branches. Thus > some kernel address will still be captured. I guess they could be eliminated > by the sw_filter. > > When using LBR priv level filtering, the filter applies to the branch target > only. Ah, indeed. I'll try and whip up a patch. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists