Instead of enrolling the local TPM to a luks volume, use the public key from a
TPM to enroll it into the luks volume. This is useful when enrolling a TPM that
is not currently accessible, for example if the TPM is located on a different
system.
Move the calculation of the sealed object policy hash out of the tpm2_seal()
function. Instead, callers of tpm2_seal() can directly call
tpm2_calculate_sealing_policy() and then provide the policy hash to
tpm2_seal().
Traditionally, TPM2 PCR policies are bound against literal PCR values,
which makes them hard to work with when updating software that is
measured into PCRs: each update will change the PCR values, and thus
break TPM2 policies of existing objects.
Let's improve the situation: let's allow signed PCR policies. Secrets
and other TPM2 objects can be associated with a public key that signs a
PCR policy. Thus, if the signed policy and the public key is presented,
access to the TPM2 object can be granted. This allows a less brittle
handling of updates: for example, whenever a kernel image is updated a
new signed PCR policy can be shipped along with it, signed by a private
key owned by the kernel vendor (ideally: same private key that is used
to sign the kernel image itself). TPM2 objects can then be bound to the
associated public key, thus allowing objects that can only be unlocked
by kernels of the same vendor. This makes it very easy to update kernels
without affecting locked secrets.
This does not hook up any of the consuming code (just passes NULL/0
everywhere). This is for later commits.
Add support for PIN enrollment with TPM2. A new "tpm2-pin" field is
introduced into metadata to signal that the policy needs to include a
PIN.
v2: fix tpm2_make_luks2_json in sd-repart
Gabríel Arthúr Pétursson
Dan Streetman
Lennart Poettering
Grigori Goronzy