Five permanent ratchets, all free today — the point is that they cannot regress
tomorrow. Each crate was re-measured at the commit, not taken from a survey.
`forbid(unsafe_code)`:
punktfunk-encode-worker the binary that carries cap_sys_nice. Its header
claims "no Wayland, no D-Bus, no network, no
plugins"; this makes the memory-safety half of that
claim mechanical. `forbid`, not `deny`, so it cannot
be re-opened by an #[allow] further down.
pf-update-check parses a signed, network-fetched manifest and its own
header says it "owns the part where being wrong is a
security bug". Signature checking is worthless if the
parser around it can be walked out of bounds.
pf-vaadec its header states the design constraint outright — it
links no libva and compiles on macOS, "which is the
point". The crate is full of hand-declared libva
repr(C) mirrors; one raw deref and it stops being the
CPU-testable half.
tools/cursor-probe free, and a probe is where "just deref it to see" is
most tempting.
`deny(unsafe_code)` + one localized allow:
pf-update root runs this. Its single unsafe operation, a bare
geteuid, moves into a named `effective_uid()` helper
carrying the crate's one #[allow(unsafe_code)].
Deliberately NOT rewritten to rustix, contrary to the programme document's first
draft: pf-update's Cargo.toml states that its zero-dependency posture IS a
security invariant of a root helper ("no HTTP client, no TLS, no argument
parsing"), and the extern block says the same. Pulling a general-purpose syscall
crate into a root helper to delete one `unsafe` would trade a real property for
a cosmetic one. The localized allow keeps the ratchet: any NEW unsafe anywhere
in the crate is a build error.
Verified: `cargo check -p pf-vaadec -p pf-update-check` and
`cargo check -p pf-update -p cursor-probe` clean on macOS, plus
`cargo check -p pf-update --target x86_64-unknown-linux-gnu` — pf-update's whole
body is behind `cfg(target_os = "linux")`, so the macOS check does not reach the
line that changed. punktfunk-encode-worker is not built here (pf-encode's C
dependencies do not cross-compile from macOS) and needs the Linux CI leg.
The root helper, its unit, the group-scoped polkit rule and the install-kind
marker all shipped with the HOST package. A Steam Deck or a handheld has no host
package, so the client half of one-tap updates had nothing to stand on.
The client packages now ship their own copies — deliberately under their own
paths (`pf-update-client`, `punktfunk-client-update.service`,
`49-punktfunk-client-update.rules`, `/usr/share/punktfunk-client/install-kind`)
rather than sharing the host's. Two packages owning one path is a hard conflict
in dpkg, rpm and pacman alike, and the client marker needs its own DIRECTORY
too because the host RPM claims `%{_datadir}/punktfunk/*` with a glob — a
sibling file there would break `dnf install punktfunk punktfunk-client`.
`pf-update` grows the matching `apply-client` verb. The verb comes from a
root-owned unit's fixed ExecStart, never from the caller, so the zero-parameter
invariant holds; both verbs sweep every installed punktfunk package, and what
the verb selects is which marker is read and which binary the run-the-binary
gate executes afterwards. A client sysext is refused with its reason: the signed
feed carries the host image, and installing that over a client-only box is not
an update.
The opt-in group is created by both packages' scriptlets, idempotently, so
whichever lands first wins.
Also fixes the host's own helper install: it read `$R/target/release/pf-update`,
which is the source checkout, while build() exports CARGO_TARGET_DIR="$srcdir/
target" and every other binary in the file installs from `$T`. Both now read
`$T`.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The U2 leg of planning:host-update-from-web-console.md. A new dep-free root helper
(crates/pf-update) runs the distro package manager against the INSTALLED punktfunk
packages — apt (index refresh scoped to our list when present), dnf, rpm-ostree
(single-transaction re-resolve, reported staged), sysext (the proven signed-feed
updater), pacman only behind the explicit PACMAN_FULL_SYSUPGRADE opt-in — then the
run-the-binary gate, then a root-written result record. Zero attacker-influenceable
parameters end to end: fixed ExecStart oneshot (punktfunk-update.service), polkit rule
scoped to that one unit's start verb for the shipped-EMPTY punktfunk-update group
(joining it is the auditable opt-in; every postinst creates it, none populate it).
The host starts the unit, interprets the record (staged / nothing-newer-yet / changed),
and crosses its own restart on the same intent/reconcile machinery as the Windows leg.
Status now reports staged results and the opt-in hint.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehler
