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189 points arjvik | 1 comments | | HN request time: 0.231s | source
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keeperofdakeys ◴[] No.42734325[source]
You can mitigate this by including PCRs that sign the kernel and initrd, however it means whenever you update you need to unlock manually. On Redhat-based distros this can be done with PCRs 8 and 9, though IIRC this may change on other distros.

Also AFAIK there is no standard way to guess the new PCRs on reboot so you can't pre-update them before rebooting. So you either need to unlock manually or use a network decryption like dracut-sshd.

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1. jansommer ◴[] No.42735137[source]
You can use tpm2_policyauthorize and allow the PCR to change without having to manually unlock. This was not supported in TPM 1.2.

You can use it with Systemd.

https://github.com/tpm2-software/tpm2-tools/blob/master/man/...