Messages in this thread | | | Date | Wed, 6 Jun 2012 14:59:29 +0200 | From | Borislav Petkov <> | Subject | Re: [PATCH] CMA: Do no enable it by default |
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On Wed, Jun 06, 2012 at 10:54:59AM +0930, Christopher Yeoh wrote: > > CROSS_MEMORY_ATTACH is a MPI feature which shouldn't be enabled by > > default on every linux system simply because the majority of users do > > not need it. > > btw although CMA was primarily written for MPI it is used by more than > just MPI implementations. For example, recent versions of strace now > use it instead of PTRACE_PEEKDATA if its available: > > http://article.gmane.org/gmane.comp.sysutils.strace.devel/2467/match=process_vm_readv
I see.
Looks like process_vm_readv() is faster than PTRACE_PEEKDATA. You could add this to the config option text so people can know why they could/should enable CMA.
Oh, and also the note about ptrace privileges below :-).
> > Besides, in the config option it says "... which allow a process with > > the correct privileges to directly read from or write to to another > > process's address space.", which, if the reading process has somehow > > gained privileges (as that never happens) is your security issue right > > there. > > The privileges required are exactly the same as required to ptrace the > target. You're rather stuffed anyway if you have a hostile process with > those privileges.
Ok.
Thanks.
-- Regards/Gruss, Boris.
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