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

From: Coiby Xu <coxu@redhat.com>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: "Baoquan He" <bhe@redhat.com>,
	"Michal Suchánek" <msuchanek@suse.de>,
	"Heiko Carstens" <hca@linux.ibm.com>,
	akpm@linux-foundation.org, kexec@lists.infradead.org,
	keyrings@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
	"Dave Young" <dyoung@redhat.com>, "Will Deacon" <will@kernel.org>,
	"Eric W . Biederman" <ebiederm@xmission.com>,
	"Chun-Yi Lee" <jlee@suse.com>,
	stable@vger.kernel.org, "Philipp Rudo" <prudo@linux.ibm.com>,
	linux-security-module@vger.kernel.org,
	"Vasily Gorbik" <gor@linux.ibm.com>,
	"Alexander Gordeev" <agordeev@linux.ibm.com>,
	"Christian Borntraeger" <borntraeger@linux.ibm.com>,
	"Sven Schnelle" <svens@linux.ibm.com>,
	"Martin Schwidefsky" <schwidefsky@de.ibm.com>,
	"open list:S390" <linux-s390@vger.kernel.org>,
	"open list" <linux-kernel@vger.kernel.org>,
	linux-integrity <linux-integrity@vger.kernel.org>,
	"Jarkko Sakkinen" <jarkko@kernel.org>
Subject: Re: [PATCH v8 4/4] kexec, KEYS, s390: Make use of built-in and secondary keyring for signature verification
Date: Thu, 16 Jun 2022 09:46:50 +0800	[thread overview]
Message-ID: <20220616014650.wd6saed72breqeyb@Rk> (raw)
In-Reply-To: <20220519171134.GN163591@kunlun.suse.cz>

Hi Mimi,

>> >
>> > 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"?
>>
[...]
>>
>> 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.

For arm64, recently I did a new round of test and the patches works as
expected,
   1. Build 5.19.0-rc2
   2. generate keys and add them to .secondary_trusted_keys, MOK, UEFI
      db; 
   3. sign different kernel images with different keys including keys
      from .builtin_trusted_key, .secondary_trusted_keys keyring, UEFI db
      key and MOK key 
   4. Without lockdown, all kernel images can be kexec'ed; with lockdown
      enabled, only the kernel image signed by the key from
      .builtin_trusted_key can be kexec'ed

Then I build a new kernel with the patches applied and confirm all
kernel images can be kexec'ed.

>
>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.

For 390, I commented out the code that skips signature verification
when secure boot is not enabled since I couldn't find a machine that
supports secure boot and confirm before applying the patch, kernel
images signed by keys from .builtin_trusted_key, .secondary_trusted_keys
couldn't be kexec'ed when lockdown is enabled; after applying the
patch, those kernel images could be kexec'ed. 

>
>Thanks
>
>Michal
>

-- 
Best regards,
Coiby

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