Messages in this thread | | | Date | Wed, 2 Oct 2013 14:59:32 +0200 | Subject | Re: [RFC] perf: mmap2 not covering VM_CLONE regions | From | Stephane Eranian <> |
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On Wed, Oct 2, 2013 at 2:46 PM, Peter Zijlstra <peterz@infradead.org> wrote: > On Wed, Oct 02, 2013 at 02:39:53PM +0200, Ingo Molnar wrote: >> - then there are timing attacks, and someone having access to a PMU >> context and who can trigger this SHA1 computation arbitrarily in task >> local context can run very accurate and low noise timing attacks... >> >> I don't think the kernel's sha_transform() is hardened against timing >> attacks, it's performance optimized so it has variable execution time >> highly dependent on plaintext input - which leaks information about the >> plaintext. > > Typical user doesn't have enough priv to profile kernel space; once you > do you also have enough priv to see kernel addresses outright (ie. > kallsyms etc..). > I was going to say just that. But that's not the default, paranoid level is at 1 by default and not 2. So I supposedly can still do:
$ perf record -e cycles ......
In per-thread mode and collect kernel level addresses.
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