Messages in this thread | | | From | Jeremy Maitin-Shepard <> | Subject | Re: [TuxOnIce-devel] RFC: Suspend-to-ram cold boot protection by encrypting page cache | Date | Tue, 30 Jun 2009 23:43:53 -0700 |
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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.
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.
-- Jeremy Maitin-Shepard
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