From: joeyli <jlee-IBi9RG/b67k@public.gmane.org>
Subject: Re: [RFC V4 PATCH 00/15] Signature verification of hibernate
 snapshot
Date: Thu, 26 Sep 2013 21:20:38 +0800
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Cc: Pavel Machek <pavel-+ZI9xUNit7I@public.gmane.org>,
	Alan Stern <stern-nwvwT67g6+6dFdvTe/nMLpVzexx5G7lz@public.gmane.org>,
	David Howells <dhowells-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-efi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-crypto-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	opensuse-kernel-stAJ6ESoqRxg9hUCZPvPmw@public.gmane.org, "Rafael J. Wysocki" <rjw-KKrjLPT3xs0@public.gmane.org>,
	Matthew Garrett <mjg59-1xO5oi07KQx4cg9Nei1l7Q@public.gmane.org>,
	Len Brown <len.brown-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Josh Boyer <jwboyer-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Matt Fleming <matt.fleming-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	James Bottomley <james.bottomley-JuX6DAaQMKPCXq6kfMZ53/egYHeGw8Jk@public.gmane.org>,
	Greg KH <gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>, JKosina-IBi9RG/b67k@public.gmane.org,
	Rusty Russell <rusty-8n+1lVoiYb80n/F98K4Iww@public.gmane.org>,
	Herbert Xu <herbert-F6s6mLieUQo7FNHlEwC/lvQIK84fMopw@public.gmane.org>,
	"David S. Miller" <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>,
	"H. Peter Anvin" <hpa-YMNOUZJC4hwAvxtiuMwx3w@public.gmane.org>, Michal Marek <mmarek-AlSwsSmVLrQ@public.gmane.org>,
	Gary Lin <GLin-IBi9RG/b67k@public.gmane.org>, Vivek Goyal <vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>
To: Vojtech Pavlik <vojtech-AlSwsSmVLrQ@public.gmane.org>
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=E6=96=BC =E5=9B=9B=EF=BC=8C2013-09-26 =E6=96=BC 14:22 +0200=EF=BC=8CVo=
jtech Pavlik =E6=8F=90=E5=88=B0=EF=BC=9A
> On Thu, Sep 26, 2013 at 02:06:21PM +0200, Pavel Machek wrote:
>=20
> > > For the symmetric key solution, I will try HMAC (Hash Message
> > > Authentication Code). It's already used in networking, hope the
> > > performance is not too bad to a big image.
> >=20
> > Kernel already supports crc32 of the hibernation image, you may wan=
t
> > to take a look how that is done.
> >=20
> > Maybe you want to replace crc32 with cryptographics hash (sha1?) an=
d
> > then use only hash for more crypto? That way speed of whatever
> crypto
> > you do should not be an issue.
>=20
> Well, yes, one could skip the CRC when the signing is enabled to gain
> a
> little speedup.=20

In current kernel, CRC is for check the integrity of LZO compressed
image, the purpose is different to check the integrity of snapshot
image.
So, CRC will not in non-compress hibernate or userspace hibernate code
path

On the other hand, attacker can easily change the CRC code in the heade=
r
of LZO hibernate image.

Thanks a lot!
Joey Lee