From: Mimi Zohar <zohar@linux.ibm.com>
To: Sasha Levin <sashal@kernel.org>
Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Maurizio Drocco <maurizio.drocco@ibm.com>,
Bruno Meneguele <bmeneg@redhat.com>,
linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH AUTOSEL 5.7 03/30] ima: extend boot_aggregate with kernel measurements
Date: Sun, 29 Nov 2020 08:17:38 -0500 [thread overview]
Message-ID: <5b8dcdaf66fbe2a39631833b03772a11613fbbbf.camel@linux.ibm.com> (raw)
In-Reply-To: <20200709012735.GX2722994@sasha-vm>
Hi Sasha,
On Wed, 2020-07-08 at 21:27 -0400, Sasha Levin wrote:
> On Wed, Jul 08, 2020 at 12:13:13PM -0400, Mimi Zohar wrote:
> >Hi Sasha,
> >
> >On Wed, 2020-07-08 at 11:40 -0400, Sasha Levin wrote:
> >> From: Maurizio Drocco <maurizio.drocco@ibm.com>
> >>
> >> [ Upstream commit 20c59ce010f84300f6c655d32db2610d3433f85c ]
> >>
> >> Registers 8-9 are used to store measurements of the kernel and its
> >> command line (e.g., grub2 bootloader with tpm module enabled). IMA
> >> should include them in the boot aggregate. Registers 8-9 should be
> >> only included in non-SHA1 digests to avoid ambiguity.
> >
> >Prior to Linux 5.8, the SHA1 template data hashes were padded before
> >being extended into the TPM. Support for calculating and extending
> >the per TPM bank template data digests is only being upstreamed in
> >Linux 5.8.
> >
> >How will attestation servers know whether to include PCRs 8 & 9 in the
> >the boot_aggregate calculation? Now, there is a direct relationship
> >between the template data SHA1 padded digest not including PCRs 8 & 9,
> >and the new per TPM bank template data digest including them.
>
> Got it, I'll drop it then, thank you!
After re-thinking this over, I realized that the attestation server can
verify the "boot_aggregate" based on the quoted PCRs without knowing
whether padded SHA1 hashes or per TPM bank hash values were extended
into the TPM[1], but non-SHA1 boot aggregate values [2] should always
include PCRs 8 & 9.
Any place commit 6f1a1d103b48 was backported [2], this commit
20c59ce010f8 ("ima: extend boot_aggregate with kernel measurements")
should be backported as well.
thanks,
Mimi
[1] commit 1ea973df6e21 ("ima: Calculate and extend PCR with digests in ima_template_entry")
[2] commit 6f1a1d103b48 ("ima: Switch to ima_hash_algo for boot aggregate")
next prev parent reply other threads:[~2020-11-29 13:18 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-08 15:40 [PATCH AUTOSEL 5.7 01/30] drm/msm: fix potential memleak in error branch Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 02/30] drm/msm/dpu: allow initialization of encoder locks during encoder init Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 03/30] ima: extend boot_aggregate with kernel measurements Sasha Levin
2020-07-08 16:13 ` Mimi Zohar
2020-07-09 1:27 ` Sasha Levin
2020-11-29 13:17 ` Mimi Zohar [this message]
2020-12-01 0:21 ` Sasha Levin
2020-12-01 3:13 ` Mimi Zohar
2020-12-02 23:53 ` Sasha Levin
2020-12-11 3:10 ` Tyler Hicks
2020-12-11 11:01 ` Mimi Zohar
2020-12-11 17:46 ` James Bottomley
2020-12-13 2:22 ` Mimi Zohar
2020-12-28 19:28 ` Ken Goldman
2020-12-29 2:01 ` Mimi Zohar
2020-12-14 16:42 ` Tyler Hicks
2021-01-12 15:35 ` Tyler Hicks
2021-01-12 16:56 ` Mimi Zohar
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 04/30] drm/exynos: Properly propagate return value in drm_iommu_attach_device() Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 05/30] drm/exynos: fix ref count leak in mic_pre_enable Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 06/30] x86/fpu: Reset MXCSR to default in kernel_fpu_begin() Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 07/30] exfat: Set the unused characters of FileName field to the value 0000h Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 08/30] exfat: call sync_filesystem for read-only remount Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 09/30] thermal/drivers: imx: Fix missing of_node_put() at probe time Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 10/30] ACPI: DPTF: Add battery participant for TigerLake Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 11/30] blk-mq-debugfs: update blk_queue_flag_name[] accordingly for new flags Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 12/30] m68k: nommu: register start of the memory with memblock Sasha Levin
2020-07-08 15:40 ` [PATCH AUTOSEL 5.7 13/30] m68k: mm: fix node memblock init Sasha Levin
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