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From: Jonathan McDowell <noodles@fb.com>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"x86@kernel.org" <x86@kernel.org>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-integrity@vger.kernel.org"
	<linux-integrity@vger.kernel.org>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>
Subject: Re: [PATCH] Carry forward IMA measurement log on kexec on x86_64
Date: Thu, 28 Apr 2022 10:40:52 +0000	[thread overview]
Message-ID: <YmpvJ5JziMS+M3j+@noodles-fedora-PC23Y6EG> (raw)
In-Reply-To: <06a1242830ddb84c52cd77e548c71d40a0eb5e63.camel@linux.ibm.com>

On Tue, Apr 26, 2022 at 02:10:58PM -0400, Mimi Zohar wrote:
> On Tue, 2022-04-26 at 16:48 +0000, Jonathan McDowell wrote:
> > Also there's an issue about the fact that we measure the kexec pieces
> > even if we don't actually do the kexec; there's no marker that confirms
> > the kexec took place. It's separate to this patch (in that it affects
> > the device tree kexec infrastructure too) but it's conceivable that an
> > attacker could measure in the new kernel details and not actually do the
> > kexec, and that's not distinguishable from the kexec happening.
> > 
> > One approach might be to add a marker in the kexec ima buffer such that
> > if it's not present we know the kexec hasn't happened, but I need to
> > think through that a bit more.
> 
> I'm not quite sure what you mean by "we measure the kexec pieces".  The
> kexec file load syscall calls kernel_read_file_from_fd() to read the
> kernel image into a buffer.  The measurement record included in the IMA
> measurement list a hash of the buffer data, which is exactly the same
> as the hash of the kernel image.
> 
> The kernel kexec self tests only do the kexec load, not the execute. 
> For each kexec execute you'll see an additional "boot_aggregate" record
> in the IMA measurement list.  At least for the moment I don't see a
> need for additional marker.

You're right, of course. I'd missed the fact we measure the
boot_aggregate into IMA_MEASURE_PCR_IDX on boot, so although we'll
update PCRs related to the kexec on load the IMA PCR won't get updated
until we've actually done the reboot. So no need for anything extra.

J.

  reply	other threads:[~2022-04-28 10:41 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-04-22 13:50 Jonathan McDowell
2022-04-25 16:29 ` Mimi Zohar
2022-04-26 12:08   ` Jonathan McDowell
2022-04-26 13:49     ` Mimi Zohar
2022-04-26 16:48       ` Jonathan McDowell
2022-04-26 18:10         ` Mimi Zohar
2022-04-28 10:40           ` Jonathan McDowell [this message]
2022-04-28 12:25             ` Mimi Zohar
2022-04-26 16:52 ` [PATCH v2] " Jonathan McDowell
2022-04-29 21:30   ` Mimi Zohar
2022-05-03 12:02     ` Jonathan McDowell
2022-05-04 13:49       ` Mimi Zohar
2022-05-09 10:40   ` Jonathan McDowell
2022-05-09 11:25     ` Boris Petkov
2022-05-09 17:46       ` Jonathan McDowell
2022-05-09 18:09         ` Borislav Petkov
2022-05-09 18:41           ` Jonathan McDowell
2022-05-09 19:40             ` Borislav Petkov
2022-05-10  8:02               ` Jonathan McDowell
2022-05-10 10:46   ` Borislav Petkov
2022-05-11  9:59   ` [PATCH v3] x86/kexec: Carry forward IMA measurement log on kexec Jonathan McDowell
2022-05-11 17:53     ` Mimi Zohar
2022-05-11 17:56       ` Borislav Petkov
2022-05-11 19:12         ` Mimi Zohar
2022-05-12  1:34       ` Mimi Zohar
2022-05-12 16:25     ` [PATCH v4] " Jonathan McDowell
2022-05-13 17:19       ` Lakshmi Ramasubramanian
2022-05-16 15:15         ` Jonathan McDowell
2022-05-17 17:19           ` Lakshmi Ramasubramanian
2022-05-18 10:42             ` Jonathan McDowell
2022-05-18 14:43       ` Mimi Zohar
2022-05-30  8:40         ` Jonathan McDowell
2022-06-03 15:55           ` Dave Hansen
2022-06-03 15:55             ` Dave Hansen
2022-06-06  3:54             ` Baoquan He
2022-06-06  3:54               ` Baoquan He
2022-06-06  4:06       ` Baoquan He
2022-06-10  9:52         ` Jonathan McDowell
2022-06-10  9:52           ` Jonathan McDowell
2022-06-13 10:30       ` [PATCH v5] " Jonathan McDowell
2022-06-13 10:30         ` Jonathan McDowell
2022-06-13 21:01         ` Mimi Zohar
2022-06-13 21:01           ` Mimi Zohar
2022-06-16  2:59           ` Baoquan He
2022-06-16  2:59             ` Baoquan He
2022-06-16 15:30         ` [PATCH v6] " Jonathan McDowell
2022-06-16 15:30           ` Jonathan McDowell
2022-06-30  8:36           ` [PATCH v7] " Jonathan McDowell
2022-06-30  8:36             ` Jonathan McDowell
2022-06-30 11:54             ` Mimi Zohar
2022-06-30 11:54               ` Mimi Zohar
2022-07-04  2:36             ` Baoquan He
2022-07-04  2:36               ` Baoquan He
2022-06-27 11:56 ` [tip: x86/kdump] " tip-bot2 for Jonathan McDowell
2022-07-01 14:37 ` tip-bot2 for Jonathan McDowell
2022-07-07 16:52 ` [tip: x86/boot] " tip-bot2 for Jonathan McDowell
2022-07-07 17:37   ` Jonathan McDowell
2022-07-07 17:50     ` Dave Hansen

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