| Filename | Latest commit message | Latest commit date |
|---|---|---|
Jorijn van der Graaf
bae21dc7a8
The templates live on the persist partition and survive a reflash; the
finger-name map lives on the rootfs and does not. A reflashed phone comes
back with the trustlet holding every template it had and the daemon
knowing none of them by name -- and with five of them the group is full, so
every enrolment from Settings answered -207 "Up to the limit" (fennek182,
2026-10-13). No D-Bus client could get out of that: the list answered from
the map, delete removed only the fids the map knew, and ENUMERATE was sent
with an empty payload and read for its count alone.
A finger re-enrolled under its old name produced the same state one
template at a time: the map took the new fid and the old template stayed
in its slot.
ENUMERATE now asks with room for every slot the group can hold, and the
reply names the templates: one 8-byte entry per loaded one, its fid in the
second word. Verified live: the three fids the map names came back among
the four listed. With the list in hand:
- An enrolment removes the templates no name accounts for before ENROLL.
They can match nothing (a verify filters on the map's fids, standby
arms from them), and each is a slot the enrolment may need or the
duplicate the trustlet would refuse it for.
- Deleting every finger deletes them too, and the job is posted even
when the map is empty, which after a reflash it is.
- Re-enrolling a finger drops its name at EnrollStart, so the old
template is unnamed and goes under the first rule. The trustlet forces
the order: with duplicate checking on, a re-enrolment of a finger it
still holds does not complete (2026-09-04: one attempt 0 accepted of 7
presses, another stalled at sample 8 of 20).
- The claim log counts them: "4 template(s) loaded, 1 of them unnamed".
The map now decides what an enrolment keeps, so the Store module says so,
and three rules keep that from turning a damaged map into lost templates.
A line the decoder cannot use -- a typo in a hand rebuild, a finger named
twice -- makes the map untrusted, and no enrolment removes anything on its
account. A line it cannot read at all is written back, word for word, by
every save but a delete of every finger, so the distrust outlasts the next
enrolment; a line it can read but not seat, the repeated name or a sixth
finger, is kept as the finger and fid it names and goes with that finger's
delete, template included, instead of coming back as the finger's name;
and the finger named twice now answers to its FIRST line, where before
the last line's fid replaced the earlier one's. A file that will not open
or read, for any reason but its absence, refuses
enrolment and deletion outright and is never written over. And the map is
written with GLib's g_file_set_contents_full under its consistent and
durable flags, and a save that did not land is reported: the old map
stays, a re-enrolment whose name drop did not land is refused with the
name put back, a delete whose save did not land removes nothing, and an
enrolment whose name did not land is reported to the client as failed,
not completed. Of the daemon's own paths, deleting every finger is the
one removal of unnamed templates on the user's word rather than the
map's: in a managed group it takes every template, named or not. A delete is refused while the
claimant's enrolment or verify for that user is in progress, because the
running job's keep-list came from the claim's map; a standby verify for
that user is stopped and the delete goes ahead. Group 0 is never tidied:
every daemon path that removes a template the map does not name, and the
name drop before a re-enrolment, asks one predicate, and it says no for
group 0 -- root's,
which no session user is, and the group a stock Android install's primary
user also writes. Root re-enrolling a finger behaves as it did before.
The --probe-remove diagnostic removes the fid it is given in any group,
with no map involved, as before.
A result belongs to the operation that asked for it. EnrollStart and
VerifyStart number the operation, the job and every event it posts carry
the number, and a Stop or the claim's end clears it: a job still queued
under a cleared number exits at dequeue instead of running an operation
nobody wants, and a result still in flight is neither named nor reported
-- its template, unnamed, goes with the group's next enrolment. Without
this, a stop followed by a new start could name a late result under the
new finger and remove the just-saved template as unnamed. An enrolment is
also refused before anything changes when the store is read-only, and the
claim's map is re-read from disk at every EnrollStart, so a file rebuilt
by hand under a held claim counts.
The probe passes the loaded list as the named one. A diagnostic does not
tidy the group it is probing. fplearn.sh's header no longer says that
re-enrolment adds a template with no trustlet-side remove, and its `enrol`
refusal gives the protocol's own reason (a template with no history)
instead of the trustlet's duplicate refusal.
Tested on the dev phone. An earlier build of this change, before the
shared predicate and the damaged-map rule, removed the phone's one stray
template at an EnrollStart for a finger not in the map (fid 1313616972,
8 -> 6 containers), reloaded the group as the three named ones, got rc=0
from ENROLL and cancelled cleanly. A build of this series then ran the
same claim and EnrollStart on the group it left behind: three loaded, none
unnamed, nothing removed, ENROLL rc=0, cancelled cleanly. The build of this
series' tip then enrolled a fourth finger to completion (20 samples
accepted, one refused), which the map saved and listed, and deleted it
again under the same claim: its template removed, the group and the map
back to the three they started with.
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| .. | ||
| 20-focal64.manifest | ||
| 80-fingerprintd.preset | ||
| actions.conf.example | ||
| APKBUILD | ||
| build-package.sh | ||
| deploy-dev.sh | ||
| fingerprint-auth.pam | ||
| fingerprintd-agent.service | ||
| fingerprintd.json | ||
| fingerprintd.modules-load.conf | ||
| fingerprintd.post-install | ||
| fingerprintd.post-upgrade | ||
| fingerprintd.service | ||
| fingerprintd.tmpfiles.conf | ||
| fingers.conf.example | ||
| fpenrol.sh | ||
| fplearn.sh | ||
| fptrial.sh | ||
| make-bin-tarball.sh | ||
| make-libqcomtee.sh | ||
| make-sysroot.sh | ||
| mnt-persist.mount | ||
| net.reactivated.Fprint.conf | ||
| net.reactivated.fprint.device.policy | ||
| net.reactivated.Fprint.service | ||
| postlogin.pam | ||
| README.config.md | ||
fingerprintd.json — where it comes from, and why this exact file
The trustlet gates its config file on common.configuration_uuid and silently
falls back to built-in defaults on a mismatch, so the file is not decorative:
SYNC_CONFIG returning 0 is what makes the whole init chain run.
This copy is generated, not hand-written. Its source is fp6fpcfg.py in the
fp6 bring-up repo, which builds it from the captured stock configuration dump
(journal/fingerprint/captures/2026-08-25-focal64-effective-config-from-stock.txt):
utilities/fp6fpcfg.py --daemon --verbose > packaging/fingerprintd.json
sha256 begins b205c756914a66f1.
Why the --verbose variant
--verbose here is the trustlet's own log level, not the daemon's. It is
shipped because it is the file every accuracy number was measured on — 30/30
held presses, zero false accepts, 36-330 ms to a verdict — and the TA's log
level cannot be raised again by a runtime SYNC_CONFIG, so a session that
needs the matcher's own lines has to have started with it.
--daemon alone produces the same file with trustlet logging off (sha256
6c4503e628406424, four diagnosis.* keys differ and nothing else). It is
plausibly the better shipping default and it is untested: no rate in the
journal was measured on it. Switching is a measurement, not an edit.
The two policy keys
common.max_authentication_rescan_times: 0— at the stock budget a wrong finger never yields a terminal frame, so a PAM client waits forever for theverify-no-matchit needs.trustlet.enable_trusted_enrollment: false— skips the challenge compare and thehw_auth_tokenHMAC verify. pmOS has no Gatekeeper to issue a token and nothing on pmOS verifies one.