Messages in this thread | | | Date | Wed, 01 Jul 2009 19:09:36 +1000 | From | Nigel Cunningham <> | Subject | Re: [TuxOnIce-devel] RFC: Suspend-to-ram cold boot protection by encrypting page cache |
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Hi again.
Jeremy Maitin-Shepard wrote: > Nigel Cunningham <ncunningham@crca.org.au> writes: > >> Hi Jeremy. >> I'd suggest emailing the Linux-PM list rather than tuxonice-devel. >> TuxOnIce devel focuses on the out-of-vanilla suspend to disk >> enhancements rather than on suspend to ram. > > The Linux-PM list is a good suggestion, but I specifically included > tuxonice because of the note at the bottom --- namely that I believe > that tuxonice in particular already includes support for much of what is > needed to implement the idea.
Ah, sorry. I read too quickly.
> Specifically, suppose right at the stage in tuxonice hibernation when > the kernel as about to write the page cache pages to disk, it instead > just encrypts in place those pages, clears the encryption key, then > waits for the userspace helper to pass it back the key again to use to > decrypt the pages. > > In fact it would seems that actually entering S3 is mostly irrelevant in > terms of the implementation. > > Tuoxnice already has code to deal with interfacing with a userspace > helper that is kept unfrozen (and its pages handled specially) while > everything else is frozen and the page cache is overwritten, which is > precisely what is needed for this idea. In particular, it seems that an > implementation of the idea I proposed would look a lot like tuxonice > with a powerdown mode of entering S3, just that instead of writing the > page cache to disk, it is encrypted in place. I suppose it could well be that > all of the facilities used by tuxonice to do this are actually already > in the kernel, in which case it is indeed not relevant to tuxonice, but > it is not clear that the uswsusp infrastructure has everything that is > needed.
You're absolutely right - TuxOnIce could be modified to do that, quite easily.
As far as the possibility of using uswsusp goes, I'd like to get Rafael's input there - he knows it much better than I do (explicitly adding him to the ccs).
Regards,
Nigel
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