From: joeyli <jlee@suse.com>
Subject: Re: [PATCH 17/18] Hibernate: introduced SNAPSHOT_SIG_HASH config
 for select hash algorithm
Date: Tue, 27 Aug 2013 18:22:17 +0800
Message-ID: <1377598937.20140.12.camel__25963.188490323$1377599051$gmane$org@linux-s257.site>
References: <1377169317-5959-1-git-send-email-jlee@suse.com>
	 <1377169317-5959-18-git-send-email-jlee@suse.com>
	 <20130825164329.GL5171@amd.pavel.ucw.cz>
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Cc: linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org, linux-efi@vger.kernel.org,
	linux-pm@vger.kernel.org, linux-crypto@vger.kernel.org,
	opensuse-kernel@opensuse.org, David Howells <dhowells@redhat.com>,
	"Rafael J. Wysocki" <rjw@sisk.pl>,
	Matthew Garrett <mjg59@srcf.ucam.org>,
	Len Brown <len.brown@intel.com>,
	Josh Boyer <jwboyer@redhat.com>,
	Vojtech Pavlik <vojtech@suse.cz>,
	Matt Fleming <matt.fleming@intel.com>,
	James Bottomley <james.bottomley@hansenpartnership.com>,
	Greg KH <gregkh@linuxfoundation.org>, JKosina@suse.com,
	Rusty Russell <rusty@rustcorp.com.au>,
	Herbert Xu <herbert@gondor.apana.org.au>,
	"David S. Miller" <davem@davemloft.net>,
	"H. Peter Anvin" <hpa@zytor.com>, Michal Marek <mmarek@suse.cz>,
	Gary Lin <GLin@suse.com>, Vivek Goyal <vgoyal@redhat.com>
To: Pavel Machek <pavel@ucw.cz>
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In-Reply-To: <20130825164329.GL5171@amd.pavel.ucw.cz>
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List-Id: linux-crypto.vger.kernel.org

=E6=96=BC =E6=97=A5=EF=BC=8C2013-08-25 =E6=96=BC 18:43 +0200=EF=BC=8CPa=
vel Machek =E6=8F=90=E5=88=B0=EF=BC=9A
> On Thu 2013-08-22 19:01:56, Lee, Chun-Yi wrote:
> > This patch introduced SNAPSHOT_SIG_HASH config for user to select w=
hich
> > hash algorithm will be used during signature generation of snapshot=
=2E
> >=20
> > v2:
> > Add define check of oCONFIG_SNAPSHOT_VERIFICATION in snapshot.c bef=
ore
> > declare pkey_hash().
> >=20
> > Reviewed-by: Jiri Kosina <jkosina@suse.cz>
> > Signed-off-by: Lee, Chun-Yi <jlee@suse.com>
> > ---
> >  kernel/power/Kconfig    |   46 +++++++++++++++++++++++++++++++++++=
+++++++++++
> >  kernel/power/snapshot.c |   27 ++++++++++++++++++++++-----
> >  2 files changed, 68 insertions(+), 5 deletions(-)
> >=20
> > diff --git a/kernel/power/Kconfig b/kernel/power/Kconfig
> > index b592d88..79b34fa 100644
> > --- a/kernel/power/Kconfig
> > +++ b/kernel/power/Kconfig
> > @@ -78,6 +78,52 @@ config SNAPSHOT_VERIFICATION
> >  	  dependent on UEFI environment. EFI bootloader should generate t=
he
> >  	  key-pair.
> > =20
> > +choice
> > +	prompt "Which hash algorithm should snapshot be signed with?"
> > +        depends on SNAPSHOT_VERIFICATION
> > +        help
> > +          This determines which sort of hashing algorithm will be =
used during
> > +          signature generation of snapshot. This algorithm _must_ =
be built into
> > +	  the kernel directly so that signature verification can take pla=
ce.
> > +	  It is not possible to load a signed snapshot containing the alg=
orithm
> > +	  to check the signature on that module.
>=20
> Like if 1000 ifdefs you already added to the code are not enough, you
> make some new ones?
> 									Pavel
>=20

This SNAPSHOT_SIG_HASH kernel config is to select which SHA algorithms
used for generate digest of snapshot. The configuration will captured b=
y
a const char* in code:

+static const char *snapshot_hash =3D CONFIG_SNAPSHOT_SIG_HASH;
+
+static int pkey_hash(void)

So, there doesn't have any ifdef block derived from this new config.


Thanks a lot!
Joey Lee

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