From: Tushar Sugandhi <tusharsu@linux.microsoft.com>
To: Mimi Zohar <zohar@linux.ibm.com>,
ebiederm@xmission.com, noodles@fb.com, bauermann@kolabnow.com,
kexec@lists.infradead.org, linux-integrity@vger.kernel.org
Cc: code@tyhicks.com, nramas@linux.microsoft.com, paul@paul-moore.com
Subject: Re: [PATCH v2 0/7] ima: kexec: measure events between kexec load and execute
Date: Tue, 14 Nov 2023 15:24:55 -0800 [thread overview]
Message-ID: <731f818d-0e48-45f8-b009-91bd6abad704@linux.microsoft.com> (raw)
In-Reply-To: <8f87e7e4fe5c5a24cdc0d3e2267eeaf00825d1bb.camel@linux.ibm.com>
On 10/27/23 08:18, Mimi Zohar wrote:
> On Thu, 2023-10-05 at 11:25 -0700, Tushar Sugandhi wrote:
>> The current Kernel behavior is IMA measurements snapshot is taken at
>> kexec 'load' and not at kexec 'execute'. IMA log is then carried
>> over to the new Kernel after kexec 'execute'.
>>
>> Some systems can be configured to call kexec 'load' first, and followed
>> by kexec 'execute' after some time. (as opposed to calling 'load' and
>> 'execute' in one single kexec command).
>
> Additional measurements may be introduced by the kexec load itself.
> Saving the measurement list as close as possible to the reboot is
> beneficial, whether or not the kexec load and kexec execute are
> executed separately.
>
True. What I am trying to say here is the longer the window between
'load' and 'execute', greater are the chances of measurements getting
added.
But as long as a single measurement gets added between 'load' and
'execute', it will break the attestation after kexec soft-reboot.
So maybe the above line in the patch description is not necessary.
I will remove.
>> In such scenario, if new IMA
>> measurements are added between kexec 'load' and kexec 'execute', the
>> TPM PCRs are extended with the IMA events between 'load' and 'execute'.
>> But those IMA events are not carried over to the new Kernel after kexec
>> soft reboot. This results in mismatch between TPM PCR quotes, and the
>> actual IMA measurements list, after the system boots into the new kexec
>> image. This mismatch results in the remote attestation failing for that
>> system.
>>
>> This patch series proposes a solution to solve this problem by allocating
>> the necessary buffer at kexec 'load' time, and populating the buffer
>> with the IMA measurements at kexec 'execute' time.
>
> How about beginning the paragraph with "To solve this problem allocate
> ... and populate ..."
>
Sure. Will do.
~Tushar
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prev parent reply other threads:[~2023-11-14 23:25 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-05 18:25 [PATCH v2 0/7] ima: kexec: measure events between kexec load and execute Tushar Sugandhi
2023-10-05 18:25 ` [PATCH v2 1/7] ima: refactor ima_dump_measurement_list to move memory allocation to a separate function Tushar Sugandhi
2023-10-13 0:28 ` Stefan Berger
2023-10-20 20:33 ` Tushar Sugandhi
2023-10-20 21:21 ` Stefan Berger
2023-10-20 21:50 ` Tushar Sugandhi
2023-10-26 20:16 ` Mimi Zohar
2023-10-27 3:25 ` Mimi Zohar
2023-11-14 22:32 ` Tushar Sugandhi
2023-11-14 22:31 ` Tushar Sugandhi
2023-10-05 18:25 ` [PATCH v2 2/7] ima: move ima_dump_measurement_list call from kexec load to execute Tushar Sugandhi
2023-10-13 0:28 ` Stefan Berger
2023-10-20 20:35 ` Tushar Sugandhi
[not found] ` <989af3e9a8621f57643b67b717d9a39fdb2ffe24.camel@linux.ibm.com>
2023-11-14 22:43 ` Tushar Sugandhi
2023-11-15 22:30 ` Tushar Sugandhi
2023-10-05 18:25 ` [PATCH v2 3/7] ima: kexec: map source pages containing IMA buffer to image post kexec load Tushar Sugandhi
2023-10-13 0:29 ` Stefan Berger
2023-10-20 20:36 ` Tushar Sugandhi
2023-10-05 18:25 ` [PATCH v2 4/7] kexec: update kexec_file_load syscall to call ima_kexec_post_load Tushar Sugandhi
2023-10-05 18:26 ` [PATCH v2 5/7] ima: suspend measurements while the buffer is being copied during kexec reboot Tushar Sugandhi
2023-10-05 18:26 ` [PATCH v2 6/7] ima: make the memory for events between kexec load and exec configurable Tushar Sugandhi
2023-10-13 0:27 ` Stefan Berger
2023-10-20 20:39 ` Tushar Sugandhi
2023-10-20 21:16 ` Stefan Berger
2023-10-20 21:53 ` Tushar Sugandhi
2023-10-05 18:26 ` [PATCH v2 7/7] ima: record log size at kexec load and execute Tushar Sugandhi
2023-10-13 0:27 ` Stefan Berger
2023-10-20 20:40 ` Tushar Sugandhi
[not found] ` <2b95e8b9ebe10a24c7cb6fc90cb2d1342a157ed5.camel@linux.ibm.com>
2023-11-14 22:48 ` Tushar Sugandhi
[not found] ` <8f87e7e4fe5c5a24cdc0d3e2267eeaf00825d1bb.camel@linux.ibm.com>
2023-10-27 19:51 ` [PATCH v2 0/7] ima: kexec: measure events between " Mimi Zohar
2023-11-15 19:21 ` Tushar Sugandhi
2023-11-14 23:24 ` Tushar Sugandhi [this message]
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