From: Peter Zijlstra <peterz@infradead.org>
To: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perfcounters: allow sysadmin to restrict non-root counting of kernel events
Date: Wed, 18 Feb 2009 13:07:20 +0100 [thread overview]
Message-ID: <1234958840.4637.61.camel@laptop> (raw)
In-Reply-To: <18843.57965.710475.395466@cargo.ozlabs.ibm.com>
On Wed, 2009-02-18 at 21:26 +1100, Paul Mackerras wrote:
> Impact: security feature
>
> This allows the sysadmin to prevent non-root users from counting
> hardware events that occur in kernel or hypervisor mode via a sysfs file:
>
> /sys/devices/system/cpu/perf_counters/restrict_kernel_events
>
> This defaults to off (0), allowing users to count kernel and hypervisor
> events, but if the sysadmin writes 1 to that file, any new counters
> created by non-root users will automatically be set to ignore kernel
> and hypervisor events.
>
> This could be useful if there is a concern that allowing non-root users
> to count kernel or hypervisor events might leak sensitive information.
I would expect it the other way around, don't allow users access to
kernel/hv events unless explicitly granted.
next prev parent reply other threads:[~2009-02-18 12:09 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-02-18 10:26 [PATCH] perfcounters: allow sysadmin to restrict non-root counting of kernel events Paul Mackerras
2009-02-18 12:07 ` Peter Zijlstra [this message]
2009-02-18 15:51 ` Ingo Molnar
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