diff options
Diffstat (limited to 'NEWS')
-rw-r--r-- | NEWS | 44 |
1 files changed, 29 insertions, 15 deletions
@@ -39,21 +39,35 @@ CHANGES WITH 252 in spe: New Features: - * systemd-measure is a new tool to precalculate and sign expected TPM2 - PCR values if a given unified kernel image (UKI) with systemd-stub is - booted. This is useful for implementing TPM2 policies on LUKS volumes - and encrypted system/service credentials, that bind robustly to a - kernel carrying such signature information. The signed expected PCR - information can be embedded inside the UKI image for this purpose so - that it is automatically available for userspace once booted. - systemd-cryptsetup and systemd-creds have been updated to make use of - this information if available in the booted kernel. Net effect: if - you boot a properly prepared kernel, disk encryption now defaults to - be locked to kernels which carry PCR signatures from the same - keypair, i.e.: if a hypothetical distro FooOS would prepare a kernel - like this, disk encryption can be naturally bound to only FooOS - kernels, and not be unlockable on other kernels. (This is optional, - and only done in case the kernel *is* prepared like that). + * systemd-measure is a new tool for precalculating and signing expected + TPM2 PCR values seen once a given unified kernel image (UKI) with + systemd-stub is booted. This is useful for implementing TPM2 policies + for LUKS encrypted volumes and encrypted system/service credentials, + that robustly bind to kernels carrying appropriate PCR signature + information. The signed expected PCR information may be embedded + inside UKI images for this purpose so that it is automatically + available in userspace, once the UKI is booted. + + systemd-cryptsetup, systemd-cryptenroll and systemd-creds have been + updated to make use of this information if available in the booted + kernel. + + Net effect: if you boot a properly prepared kernel, TPM-bound disk + encryption now defaults to be locked to kernels which carry PCR + signatures from the same signature key pair. Example: if a + hypothetical distro FooOS prepares its UKI kernels like this, + TPM-based disk encryption is now – by default – bound to only FooOS + kernels, and encrypted volumes bound to the TPM cannot be unlocked on + other kernels from other sources. (But do note this behaviour + requires preparation/enabling in the UKI, and of course users can + always enroll non-TPM ways to unlock the volume.) + + Binding TPM-based disk encryption to public keys/signatures of PCR + values — instead of literal PCR values — addresses the inherent + "brittleness" of traditional PCR-bound TPM disk encryption schemes: + disks remain accessible even if the UKI image is updated, without any + prepartion during the update scheme — as long as each UKI carries the + necessary PCR signature information. * systemd-pcrphase is a new tool that is invoked at 4 places during system runtime, and measures additional words into TPM2 PCR 11, to |