From: Eric Biggers <ebiggers@kernel.org>
To: Aditya Prakash <adiprakash@cs.stonybrook.edu>
Cc: dm-crypt@saout.de
Subject: [dm-crypt] Re: [DM-Verity][HELP] Unlock Verity Target during runtime
Date: Wed, 17 Mar 2021 20:11:24 -0700 [thread overview]
Message-ID: <YFLE3Ct3CJrZ4yuB@sol.localdomain> (raw)
In-Reply-To: <CAA+CgzbKRQYVa=O6h-cnYpvBEyk4zEB17UkR8nVKnBxGQy6q+g@mail.gmail.com>
On Wed, Mar 17, 2021 at 04:09:46PM -0700, Aditya Prakash wrote:
> Hi,
> I am trying to implement DM-Verity for the rootfs. However, I am not sure
> what the scope of DM Verity. I can see that given a root/sudo user, I can
> unload the verity target, write to rootfs and format and load it again, is
> it possible that this is normal that can be carried out using rootkits or
> any privileged app?
> Also, how can DM-Verity ensure that the system boots to correct rootfs if
> rootfs was changed after an OTA?
> Please help me to understand the actual scope of DM Verity
>
> Thanks,
> AP
dm-verity's only job is to verify the contents of a block device against a root
hash which is provided by userspace when setting up the dm-verity target.
It's up to the userspace code setting up dm-verity to provide the "correct" root
hash -- for example, by verifying that the root hash is digitally signed by a
trusted source.
Take a look at how dm-verity is used in Verified Boot in Android and Chrome OS,
for example. There are multiple components, and dm-verity is just one of them.
- Eric
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prev parent reply other threads:[~2021-03-18 3:21 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-17 23:09 [dm-crypt] [DM-Verity][HELP] Unlock Verity Target during runtime Aditya Prakash
2021-03-18 3:11 ` Eric Biggers [this message]
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