@Foxboron @pid_eins does that also guard against an unauthorized kernel collaborating with an interposer to power-cycle the TPM and then pretend to the TPM that the system is going through a reboot? with something like the Host Secret approach from https://trustedcomputinggroup.org/wp-content/uploads/TCG_-CPU_-TPM_Bus_Protection_Guidance_Active_Attack_Mitigations-V1-R30_PUB-1.pdf ? https://www.kernel.org/doc/html/next/security/tpm/tpm-security.html doesn't read to me like Linux setups guard against that, though I am not an expert on TPM stuff and might well be missing something...

@pid_eins but do we have the software/hardware infrastructure needed to actually make this secure on a typical Linux desktop machine?
To me, the core purpose of disk encryption is protect a machine against an attacker who steals the entire, powered-off machine; and it's easy to mess up unattended disk encryption so that this is easy to break. The communication with the TPM needs to be protected against interposer attacks somehow (see https://www.nccgroup.com/us/research-blog/tpm-genie-interposer-attacks-against-the-trusted-platform-module-serial-bus/ ); the disk ideally should not just be encrypted but also integrity-protected (because in some settings, the disk encryption is then relied on for security against adaptive online attacks instead of security against a one-time-snapshot passive attacker); you need rollback protection against someone booting a super vulnerable outdated OS image; bugs in device drivers turn into disk encryption bypasses (and notably Linux basically trusts PCI devices to not be actively evil); and so on.

So I'm worried that providing TPM-based disk unlock as an easy-to-configure mechanism might give people a false sense of security. With password-based disk encryption, to me, the core security promise is easy: If someone steals your (not-too-recently-) powered-off computer, they can't get any of the data out of it unless they break your password. With TPM-based unlock, the story is a lot more complex...

@danderson are there separate maps for physical and legal coastlines?