Jorijn asked whether re-enrolling a finger overwrites its template. It does
not. The trustlet stores a new one and keeps the old, because
FF_CMD_TA_REMOVE is not implemented -- the group on this device now holds six
templates, including one from the research harness and a pair from an
enrolment two configs ago.
The trustlet identifies against every template loaded in the group, and this
daemon reported verify-match for whatever fid came back. So a request naming
one finger was answered by any of them, including templates no name maps to
any more. That is wrong by fprintd's contract, and it also means the last
measurement was taken against the union of every template ever enrolled here
rather than against the one under test.
VerifyStart now computes which fids may answer -- the named finger's, or every
named finger's for "any" -- and a match on anything else is not a match for
that request. A fid that no name maps to answers for nothing at all.
This does not reclaim the slots. Five templates per group is the configured
limit and stale ones still occupy it; removing them needs FF_CMD_TA_REMOVE,
whose payload is not reverse-engineered.
Jorijn van der Graaf
faf0dd9ba1