linux-kernel - Re: [PATCH v8 4/4] kexec, KEYS, s390: Make use of built-in and secondary keyring for signature verification

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Date:   Thu, 19 May 2022 19:11:34 +0200
From:   Michal Suchánek <msuchanek@...e.de>
To:     Baoquan He <bhe@...hat.com>
Cc:     Mimi Zohar <zohar@...ux.ibm.com>, Coiby Xu <coxu@...hat.com>,
        Heiko Carstens <hca@...ux.ibm.com>, akpm@...ux-foundation.org,
        kexec@...ts.infradead.org, keyrings@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Dave Young <dyoung@...hat.com>, Will Deacon <will@...nel.org>,
        "Eric W . Biederman" <ebiederm@...ssion.com>,
        Chun-Yi Lee <jlee@...e.com>, stable@...r.kernel.org,
        Philipp Rudo <prudo@...ux.ibm.com>,
        linux-security-module@...r.kernel.org,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Martin Schwidefsky <schwidefsky@...ibm.com>,
        "open list:S390" <linux-s390@...r.kernel.org>,
        open list <linux-kernel@...r.kernel.org>,
        linux-integrity <linux-integrity@...r.kernel.org>,
        Jarkko Sakkinen <jarkko@...nel.org>
Subject: Re: [PATCH v8 4/4] kexec, KEYS, s390: Make use of built-in and
 secondary keyring for signature verification

On Thu, May 19, 2022 at 10:22:15PM +0800, Baoquan He wrote:
> On 05/19/22 at 07:56am, Mimi Zohar wrote:
> > [Cc'ing Jarkko, linux-integrity]
> > 
> > On Thu, 2022-05-19 at 08:39 +0800, Baoquan He wrote:
> > > On 05/18/22 at 01:29pm, Heiko Carstens wrote:
> > > > On Thu, May 12, 2022 at 03:01:23PM +0800, Coiby Xu wrote:
> > > > > From: Michal Suchanek <msuchanek@...e.de>
> > > > > 
> > > > > commit e23a8020ce4e ("s390/kexec_file: Signature verification prototype")
> > > > > adds support for KEXEC_SIG verification with keys from platform keyring
> > > > > but the built-in keys and secondary keyring are not used.
> > > > > 
> > > > > Add support for the built-in keys and secondary keyring as x86 does.
> > > > > 
> > > > > Fixes: e23a8020ce4e ("s390/kexec_file: Signature verification prototype")
> > > > > Cc: stable@...r.kernel.org
> > > > > Cc: Philipp Rudo <prudo@...ux.ibm.com>
> > > > > Cc: kexec@...ts.infradead.org
> > > > > Cc: keyrings@...r.kernel.org
> > > > > Cc: linux-security-module@...r.kernel.org
> > > > > Signed-off-by: Michal Suchanek <msuchanek@...e.de>
> > > > > Reviewed-by: "Lee, Chun-Yi" <jlee@...e.com>
> > > > > Acked-by: Baoquan He <bhe@...hat.com>
> > > > > Signed-off-by: Coiby Xu <coxu@...hat.com>
> > > > > ---
> > > > >  arch/s390/kernel/machine_kexec_file.c | 18 +++++++++++++-----
> > > > >  1 file changed, 13 insertions(+), 5 deletions(-)
> > > > 
> > > > As far as I can tell this doesn't have any dependency to the other
> > > > patches in this series, so should I pick this up for the s390 tree, or
> > > > how will this go upstream?
> > > 
> > > Thanks, Heiko.
> > > 
> > > I want to ask Mimi if this can be taken into KEYS-ENCRYPTED tree.
> > > Otherwise I will ask Andrew to help pick this whole series.
> > > 
> > > Surely, this patch 4 can be taken into s390 seperately since it's
> > > independent, both looks good.
> > 
> > KEYS-ENCRYTPED is a type of key, unrelated to using the .platform,
> > .builtin, .machine, or .secondary keyrings.  One of the main reasons
> > for this patch set is to use the new ".machine" keyring, which, if
> > enabled, is linked to the "secondary" keyring.  However, the only
> > reference to the ".machine" keyring is in the cover letter, not any of
> > the patch descriptions.  Since this is the basis for the system's
> > integrity, this seems like a pretty big omission.
> > 
> > From patch 2/4:
> > "The code in bzImage64_verify_sig makes use of system keyrings
> > including
> > .buitin_trusted_keys, .secondary_trusted_keys and .platform keyring to
> > verify signed kernel image as PE file..."
> > 
> > From patch 3/4:
> > "This patch allows to verify arm64 kernel image signature using not
> > only
> > .builtin_trusted_keys but also .platform and .secondary_trusted_keys
> > keyring."
> > 
> > From patch 4/4:
> > "... with keys from platform keyring but the built-in keys and
> > secondary keyring are not used."
> > 
> > This patch set could probably go through KEYS/KEYRINGS_INTEGRITY, but
> > it's kind of late to be asking.  Has it been in linux-next?  Should I
> > assume this patch set has been fully tested or can we get some "tags"?
> 
> Right, it should be KEYS/KEYRINGS_INTEGRITY related, I made mistaken.
> Now it got two ACKs from Michal and me. Michal met the same issue on
> arm64 and posted another series of patches, finally Coiby integrated
> Michal's patch and his to make this patchset. That would be great if
> this can get reviewing from experts on key/keyring. Surely, Coiby need
> update the patch log to add the '.machine' keyring into patch logs as
> you pointed out.
> 
> IIRC, Coiby has tested it on x86_64/arm64, not sure if he took test on
> s390. No, this hasn't been in linux-next.

I used the s390 code on powerpc and there it did not work because the
built-in key was needed to verify the kernel.

I did not really run this on s390, only ported the fix I needed on
powerpc back to s390.

Thanks

Michal