Messages in this thread | | | Date | Wed, 2 Oct 2013 17:22:10 +0200 | From | Ingo Molnar <> | Subject | Re: [RFC] perf: mmap2 not covering VM_CLONE regions |
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* 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 didn't mean profiling - that's not a 'timing attack'.
A simple RDTSC done around repeated calls to sha_transform() using kernel functionality is.
Thanks,
Ingo
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