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A verify nobody answered is not a failure, and the trustlet is not ours to ship

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Two things the packaging left behind.

A verify that ran its 600-frame budget without the sensor being touched was
reported to the client as verify-unknown-error. Nothing had gone wrong: nobody
had pressed. It cost three verifications during packaging, each reading as a
broken daemon. fprintd's contract is that a verify runs until the client stops
it, so the frame cap bounds one trustlet scan session rather than the user's
patience, and a window with no press simply runs again. Verified across the
rollover: 600 frames untouched, "still waiting", then a press matching on its
first contact frame in 44 ms.

Presses that happen and never reach a verdict now report verify-retry-scan --
a bad scan, which fprintd has a word for, and not the matcher saying no.

The cost is that an unanswered verify polls every ~200 ms for as long as the
client holds it. The cure is measured and available -- gpio75 is silent at
idle and bursts on contact -- but it would make the IRQ the only way a press
is ever noticed, deleting the poll under every rate this daemon has been
measured at. Noted where the loop waits, not done.

And the trustlet: focal64.mbn is a proprietary OEM-signed blob, so the package
ships a fp6-vendor-blobs manifest fragment instead, the same mechanism
soc-fairphone-fp6-audio uses for the amp config. It needed a new directive
there -- a QTEE image is an ELF header file plus one payload per program
header, not one file -- and reassembly on the phone reproduces the image QTEE
has accepted since August, byte for byte.
This commit is contained in:
Jorijn van der Graaf 2026-09-05 04:01:06 +02:00
commit b228287c5b
5 changed files with 67 additions and 5 deletions
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16
packaging/APKBUILD
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@ -10,7 +10,7 @@
# Alpine, so an APKBUILD that compiled from source could not be built by
# anyone but us either.
pkgname=fingerprintd
pkgver=0.1.1
pkgver=0.1.2
pkgrel=0
pkgdesc="Fingerprint daemon for the Fairphone 6 (FocalTech FT9391 behind QTEE)"
url="https://forgejo.catcrafts.net/Catcrafts/fingerprintd"
@ -25,7 +25,12 @@ license="GPL-3.0-only"
# (i:fprintd=1.94.5-r1), so the provides below breaks that condition and apk
# would purge it as no-longer-needed. Depending on it explicitly is what keeps
# it. It has no dependency on fprintd itself, so nothing is being forced.
depends="dbus glib libc++ fprintd-pam"
#
# fp6-vendor-blobs runs the manifest fragment below, which reassembles the
# trustlet out of the stock modem partition on first boot. Without it there is
# no matcher and the unit stays inert on its ConditionPathExists -- so this is
# a real dependency, not a nicety. It is an FP6 device package; so is this.
depends="dbus glib libc++ fprintd-pam fp6-vendor-blobs"
# The versioned provides both satisfies plasma-workspace's fprintd dependency
# — its Users KCM is the fingerprint enrolment UI and speaks exactly this bus
# name — and EXCLUDES the real package, which is required rather than tidy:
@ -89,6 +94,13 @@ package() {
# two policy keys in it were each forced by a measurement.
install -Dm644 fingerprintd.json \
"$pkgdir"/usr/lib/firmware/fingerprintd.json
# the trustlet is NOT in this package and never will be: it is a
# proprietary OEM-signed blob. This tells fp6-vendor-blobs how to
# reassemble it from the phone's own stock partitions, which is the
# same mechanism soc-fairphone-fp6-audio uses for the amp config.
install -Dm644 20-focal64.manifest \
"$pkgdir"/usr/share/fp6-vendor-blobs/manifest.d/20-focal64.manifest
}
systemd() {