`punktfunk-sysext` checked the SHA256 of every image it downloaded, which sounds
like verification but isn't: SHA256SUMS lives on the same registry as the images
it describes, so anything able to replace an image could replace its checksum in
the same request. The checksum only ever proved the download wasn't corrupted.
Each feed now carries SHA256SUMS.asc, a detached OpenPGP signature over the
manifest, and the client verifies it before believing a line of it. The key is
packages@unom.io (AF245C506F4E4763) — the same one that already signs our RPMs,
so boxes have one key to trust and we have one key to rotate. Its public half is
baked into the script rather than fetched from the feed, because a key you fetch
from the thing you're authenticating authenticates nothing; gpg (present on
Bazzite) does the verifying against a throwaway keyring holding only that key, so
"good signature" and "signed by us" are the same statement.
Rollout: stable feeds only publish on a tag, so a `--seal` mode re-signs an
existing manifest without rebuilding an image, and every rpm.yml run seals the
OTHER channel of its Fedora major too. Canary pushes are frequent, so all live
feeds seal within a day of this landing and a key rotation propagates without
republishing anything. Until a feed is sealed the client refuses it and says so,
naming PUNKTFUNK_SYSEXT_ALLOW_UNSIGNED=1 as the informed way through.
Two things testing changed. The baked-key fingerprint check compared against an
empty string — the armor block is a single-quoted shell literal, so the extracted
range carried `FEED_KEY='` on its first line and gpg saw no armor at all; every
publish would have "mismatched" and, on a tag, failed the release. And `status`
captured fetch_manifest's stderr but only printed it on failure, swallowing the
ALLOW_UNSIGNED warning precisely when someone was running unverified.
Verified end to end on Bazzite 44 against a file:// feed with a throwaway key:
unsigned feed refused; ALLOW_UNSIGNED=1 proceeds and says so; wrong signer
rejected; tampered manifest rejected; good signature accepted; `update` exits 1
before touching anything on a bad feed. Publisher side: signs when the baked key
matches, refuses on mismatch, refuses with no key, and its signature round-trips
through the real client. shellcheck clean.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Layering is a last resort per the Bazzite docs (slows every OS update, can
block upgrades until removed); a sysext never enters an rpm-ostree
transaction, survives OS updates, and installs/updates with no reboot —
the mechanism Fedora Atomic ships via fedora-sysexts.
- build-sysext.sh wraps the built host+web RPMs into punktfunk-<V-R>-x86-64.raw:
/etc payload relocated to /usr/share/punktfunk/etc (a sysext carries only
/usr), the punktfunk-sysext helper embedded, ID=fedora + VERSION_ID pinned
(merges on Bazzite via ID_LIKE; REFUSED after a major rebase instead of
running soname-broken binaries — both behaviors validated live on Bazzite 43).
SELinux labels are baked in as squashfs pseudo-xattrs from matchpathcon:
unlabeled files run fine for user units but system daemons are DENIED
(udev couldn't read the gamepad rule under enforcing) — validated on-glass.
Refuses duplicate input package names (a stale noarch punktfunk-web next to
the x86_64 one built a chimera image with the dead node launcher once).
- punktfunk-sysext.sh: install/update/status/remove against per-Fedora-major
feeds (…/generic/punktfunk-sysext/f43[-canary]), SHA-256-verified, applies
the udev/sysctl scriptlet work + /etc copies, prints the layering-migration
hint. Live-validated on the .41 Bazzite box incl. service restart + web console.
- publish-sysext-feed.sh + rpm.yml: build + publish the image per matrix leg
(fedver 43/44), canary feeds pruned to 6, stable release assets attached.
- update-punktfunk.sh warns when the sysext shadows a layered install.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehlerandClaude Opus 5