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Date:   Wed, 8 Aug 2018 19:50:36 +0200
From:   Pavel Machek <pavel@ucw.cz>
To:     Yu Chen <yu.c.chen@intel.com>
Cc:     Ryan Chen <yu.chen.surf@gmail.com>, jlee@suse.com,
        oneukum@suse.com, "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
        ebiggers@google.com, Theodore Ts'o <tytso@mit.edu>,
        smueller@chronox.de, denkenz@gmail.com,
        Linux PM list <linux-pm@vger.kernel.org>,
        linux-crypto@vger.kernel.org,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        kookoo.gu@intel.com, Zhang Rui <rui.zhang@intel.com>
Subject: Re: [PATCH 0/4][RFC v2] Introduce the in-kernel hibernation
 encryption
Message-ID: <20180808175036.GA16217@amd>
References: <1532346156.3057.11.camel@suse.com>
 <20180723162302.GA4503@sandybridge-desktop>
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 <20180726081404.GG4244@linux-l9pv.suse>
 <20180730170415.GQ4244@linux-l9pv.suse>
 <20180803033702.GB416@sandybridge-desktop>
 <20180803053445.GC4244@linux-l9pv.suse>
 <CADjb_WSURQz86+E8kakNf7UBDM+aho+uaz3QdDkuGsEgan=szw@mail.gmail.com>
 <20180805100200.GB22948@amd>
 <20180806084534.GB12124@chenyu-desktop>
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Hi!

> > > > User space doesn't need to involve. The EFI root key is generated by
> > > > EFI boot stub and be transfer to kernel. It's stored in EFI boot se=
rvice
> > > > variable that it can only be accessed by trusted EFI binary when
> > > > secure boot is enabled.
> > > >
> > > Okay, this apply to the 'suspend' phase, right?
> > > I'm still a little confused about the 'resume' phase.
> > > Taking encryption as example(not signature),
> > > the purpose of doing hibernation encryption is to prevent other users
> > > from stealing ram content. Say, user A uses a  passphrase to generate=
 the
> >=20
> > No, I don't think that's purpose here.
> >=20
> > Purpose here is to prevent user from reading/modifying kernel memory
> > content on machine he owns.
> >
> Say, A puts his laptop into hibernation and walks away,
> and B walks by, and opens A's laptop and wakes up the system and he
> can do what he wants. Although EFI key/TPM trusted key is enabled,
> currently there's no certification during resume, which sounds
> unsafe to me. Afterall, the original requirement is to probe

Define unsafe.

If you want security against bad people resuming your machines, please
take a look at existing uswsusp solutions. It defends against that.

If you want security against bad people tampering with your machines
physically, sorry, there's no way to defend against that.

But I thought you were trying to do something for secure boot, and "bad
person resumes your machine" is out of scope there.

So please always explain security against _what kind of attack_ you
are trying to improve; intelligent communication is not possible
without that.

								Pavel

--=20
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo=
g.html

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