[systemd-devel] Enrolling PCR11 does not work as expected

Felix Rubio felix at kngnt.org
Wed Jul 5 06:30:39 UTC 2023


Hi everybody,

In my setup (sd-boot+UKI+LUKS) I am using PCRs 7+11+14 to unlock the 
LUKS drive. Should I use only PCRs 7+14 everything works, but when I add 
11 I need to provide the rescue password every single time I boot.

I have extracted the values of those PCRs using tpm2_pcrread in two 
consecutive boots, and they are equal, so at least the issue is 
reproducible.

To enroll the PCRs, after a new kernel (and, therefore, the UKI) has 
been generated, I run the following command:

systemd-cryptenroll --wipe-slot=tpm2 --tpm2-device=auto 
--tpm2-pcrs=7+11+14 <device>

After reading the documentation on systemd-measure (that I am not using 
at the moment): could it be that there are events added to PCR 11 after 
the unlocking has happened, so that I am enrolling the wrong PCR value? 
Otherwise... what am I doing wrong?

Felix


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