#3880 bound /dev/tpmrm0 into the store's container, which was necessary and
not sufficient: a bind mount preserves the host's ownership, openbao runs as a
DynamicUser with an empty CapabilityBoundingSet (so no CAP_DAC_OVERRIDE), and
the host applies no tpm udev rule at all — measured, 0 hits across all 41 host
closures against 62 rule files as a control. The node therefore keeps the
kernel default and the seal cannot open it.
A name cannot fix this. NixOS allocates system groups at activation, per
machine, so `tss` — or any group declared on both sides — gets two different
ids, and the device node carries the number. mara picked pinning a gid with an
overridable default (deploy.bao.tpmGid).
The default sits above the range NixOS auto-assigns system groups from
(400-999, measured in update-users-groups.pl) and above the normal-user range,
and below systemd's DynamicUser range (61184-65519), so it collides with
nothing any of those allocate.
The module-eval case compares the two sides rather than checking each against
a literal: the property is that they AGREE, not what they agree on. Its
absence arm is a shamir store, which never opens a TPM and must not claim a
device node's group — without it, pinning unconditionally would look identical.
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