Catcrafts/fingerprintd
Watch
2
0
Fork
You've already forked fingerprintd
 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions
fingerprintd/README.md

48 lines
1.7 KiB
Markdown
Raw Permalink Normal View History

Initial commit: the gpfile wire format, pinned by two real containers fingerprintd will own the FP6's fingerprint sensor: the rail, the QTEE session, the storage callbacks QTEE makes back into the normal world, and net.reactivated.Fprint so pam_fprintd and the desktop need no changes. None of that runs yet. What is here is the first core module and the machinery around it. Fingerprintd:Sfs is the gpfile listener's frame -- the callback that carries 47 of 66 storage requests during an enrolment. It is parse, reply and root mapping only: no file I/O, no TEE, no allocation of the shared buffer. The daemon shell supplies those, which is what lets every byte-level decision be tested on a dev box with no phone. The module exists mainly to hold one fact. READ answers at req+0x00c and WRITE reads its payload from req+0x110, because the frame is a union: a WRITE still needs its path while the payload is copied out, so it sits past the 256-byte path field, while a READ has consumed the path and packs its reply over it. Conflating them is wrong in both directions with the same symptom -- the container does not round-trip, QTEE's HMAC check fails, and the file is unlinked as tampered on the next session. So the tests do not assert the constants against themselves. They load two real containers off the phone -- one written correctly, one written with the offsets conflated -- and re-derive the bug: the broken one opens with ASCII path text rather than a binary HMAC, that text is the group name from character 8 because the read offset is 8 bytes into the path field, and the real container sits exactly 0x104 further in. Then a write-store-read round trip must be the identity, and the same round trip through a single offset must not be. O_TRUNC gets a static_assert of its own. QTEE writes a container as write(0,4096), write(4096,N), write(0,4096), so truncating on open leaves 4096 bytes where a 258850-byte template belongs; it unlinks a file it means to shorten rather than relying on the opener. Verified by mutation: conflating the offsets, making DataOffset return the read offset for writes, and setting O_TRUNC each fail the suite.
2026-09-02 16:02:46 +02:00
# fingerprintd
Fingerprint daemon for the Fairphone 6 (`milos`, SM7635) on mainline Linux.
`fingerprintd-core` is a static library with no GLib, no libqcomtee and no
system headers. Everything in it is a wire format or a state machine that was
recovered by reverse-engineering, so all of it is pinned by tests that run on a
dev box with no phone, no TEE and no sensor. The daemon shell holds everything
that touches hardware.
## Build
```sh
crafter-build # bin/fingerprintd-<target>-<march>/fingerprintd
crafter-build test # the unit suites
```
Cross-compiling for the phone:
```sh
readme
2026-09-05 22:35:23 +02:00
packaging/make-sysroot.sh
crafter-build -- --target=aarch64-alpine-linux-musl --sysroot=~/.cache/fingerprintd/sysroot-aarch64-alpine --march=armv8-a --mtune=generic
crafter-build test --target=aarch64-alpine-linux-musl --sysroot=~/.cache/fingerprintd/sysroot-aarch64-alpine --march=armv8-a --mtune=generic
Initial commit: the gpfile wire format, pinned by two real containers fingerprintd will own the FP6's fingerprint sensor: the rail, the QTEE session, the storage callbacks QTEE makes back into the normal world, and net.reactivated.Fprint so pam_fprintd and the desktop need no changes. None of that runs yet. What is here is the first core module and the machinery around it. Fingerprintd:Sfs is the gpfile listener's frame -- the callback that carries 47 of 66 storage requests during an enrolment. It is parse, reply and root mapping only: no file I/O, no TEE, no allocation of the shared buffer. The daemon shell supplies those, which is what lets every byte-level decision be tested on a dev box with no phone. The module exists mainly to hold one fact. READ answers at req+0x00c and WRITE reads its payload from req+0x110, because the frame is a union: a WRITE still needs its path while the payload is copied out, so it sits past the 256-byte path field, while a READ has consumed the path and packs its reply over it. Conflating them is wrong in both directions with the same symptom -- the container does not round-trip, QTEE's HMAC check fails, and the file is unlinked as tampered on the next session. So the tests do not assert the constants against themselves. They load two real containers off the phone -- one written correctly, one written with the offsets conflated -- and re-derive the bug: the broken one opens with ASCII path text rather than a binary HMAC, that text is the group name from character 8 because the read offset is 8 bytes into the path field, and the real container sits exactly 0x104 further in. Then a write-store-read round trip must be the identity, and the same round trip through a single offset must not be. O_TRUNC gets a static_assert of its own. QTEE writes a container as write(0,4096), write(4096,N), write(0,4096), so truncating on open leaves 4096 bytes where a 258850-byte template belongs; it unlinks a file it means to shorten rather than relying on the opener. Verified by mutation: conflating the offsets, making DataOffset return the read offset for writes, and setting O_TRUNC each fail the suite.
2026-09-02 16:02:46 +02:00
```
readme
2026-09-05 19:58:35 +02:00
Verified on the device: all five suites pass cross-built and run on the phone
itself, not only under emulation.
Add the cross-build sysroot recipe, verified on the device packaging/make-sysroot.sh populates a minimal Alpine aarch64 rootfs with apk-tools-static, so a cross build needs no root, no qemu and no phone. Adapted from imsd's, plus glib-dev for the bus layer that is coming. Building against a real Alpine sysroot means the binary links dynamically against the phone's own musl and libc++ -- libc++, libc++abi, libunwind and libgcc_s are all already on pmOS. The harness this daemon replaces had to be built -static, but only because it was built with the host's glibc toolchain; that constraint was never about the target. The pipeline is proven end to end rather than assumed: the cross-built binary runs on the phone, and all five core suites pass there too -- on the real hardware, not just under qemu-aarch64. That matters for modules that are almost entirely little-endian field packing and offset arithmetic.
2026-09-02 17:34:27 +02:00
README: it works end to end through fprintd's own clients
2026-09-02 22:29:59 +02:00
```
fprintd-enroll -f right-index-finger user ten stages, enroll-completed
fprintd-list user - #0: right-index-finger
fprintd-verify user (wrong finger) verify-no-match, on the first press
fprintd-verify user (enrolled finger) verify-match, on the first press
```
Update README.md
2026-09-06 13:56:44 +00:00
## Runtime dependencies
Initial commit: the gpfile wire format, pinned by two real containers fingerprintd will own the FP6's fingerprint sensor: the rail, the QTEE session, the storage callbacks QTEE makes back into the normal world, and net.reactivated.Fprint so pam_fprintd and the desktop need no changes. None of that runs yet. What is here is the first core module and the machinery around it. Fingerprintd:Sfs is the gpfile listener's frame -- the callback that carries 47 of 66 storage requests during an enrolment. It is parse, reply and root mapping only: no file I/O, no TEE, no allocation of the shared buffer. The daemon shell supplies those, which is what lets every byte-level decision be tested on a dev box with no phone. The module exists mainly to hold one fact. READ answers at req+0x00c and WRITE reads its payload from req+0x110, because the frame is a union: a WRITE still needs its path while the payload is copied out, so it sits past the 256-byte path field, while a READ has consumed the path and packs its reply over it. Conflating them is wrong in both directions with the same symptom -- the container does not round-trip, QTEE's HMAC check fails, and the file is unlinked as tampered on the next session. So the tests do not assert the constants against themselves. They load two real containers off the phone -- one written correctly, one written with the offsets conflated -- and re-derive the bug: the broken one opens with ASCII path text rather than a binary HMAC, that text is the group name from character 8 because the read offset is 8 bytes into the path field, and the real container sits exactly 0x104 further in. Then a write-store-read round trip must be the identity, and the same round trip through a single offset must not be. O_TRUNC gets a static_assert of its own. QTEE writes a container as write(0,4096), write(4096,N), write(0,4096), so truncating on open leaves 4096 bytes where a 258850-byte template belongs; it unlinks a file it means to shorten rather than relying on the opener. Verified by mutation: conflating the offsets, making DataOffset return the read offset for writes, and setting O_TRUNC each fail the suite.
2026-09-02 16:02:46 +02:00
readme
2026-09-05 19:58:35 +02:00
The `focal64` trustlet is proprietary and is not in this repo. It is
Initial commit: the gpfile wire format, pinned by two real containers fingerprintd will own the FP6's fingerprint sensor: the rail, the QTEE session, the storage callbacks QTEE makes back into the normal world, and net.reactivated.Fprint so pam_fprintd and the desktop need no changes. None of that runs yet. What is here is the first core module and the machinery around it. Fingerprintd:Sfs is the gpfile listener's frame -- the callback that carries 47 of 66 storage requests during an enrolment. It is parse, reply and root mapping only: no file I/O, no TEE, no allocation of the shared buffer. The daemon shell supplies those, which is what lets every byte-level decision be tested on a dev box with no phone. The module exists mainly to hold one fact. READ answers at req+0x00c and WRITE reads its payload from req+0x110, because the frame is a union: a WRITE still needs its path while the payload is copied out, so it sits past the 256-byte path field, while a READ has consumed the path and packs its reply over it. Conflating them is wrong in both directions with the same symptom -- the container does not round-trip, QTEE's HMAC check fails, and the file is unlinked as tampered on the next session. So the tests do not assert the constants against themselves. They load two real containers off the phone -- one written correctly, one written with the offsets conflated -- and re-derive the bug: the broken one opens with ASCII path text rather than a binary HMAC, that text is the group name from character 8 because the read offset is 8 bytes into the path field, and the real container sits exactly 0x104 further in. Then a write-store-read round trip must be the identity, and the same round trip through a single offset must not be. O_TRUNC gets a static_assert of its own. QTEE writes a container as write(0,4096), write(4096,N), write(0,4096), so truncating on open leaves 4096 bytes where a 258850-byte template belongs; it unlinks a file it means to shorten rather than relying on the opener. Verified by mutation: conflating the offsets, making DataOffset return the read offset for writes, and setting O_TRUNC each fail the suite.
2026-09-02 16:02:46 +02:00
extracted from the device's own stock Android partition on first boot by the
Update README.md
2026-09-06 13:56:44 +00:00
`fp6-vendor-blobs` mechanism, the same way other firmware in fp6-img is.
readme
2026-09-05 19:58:09 +02:00
## License
GPL-3.0-only, see LICENSE.
## Copyright
Copyright (C) 2026 Catcrafts® catcrafts.net
Reference in a new issue Copy permalink