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acrogenesis d593847728 Fail the suite on privileged writes through unquoted heredocs

An installer that writes a root-owned file through a heredoc with an
unquoted delimiter (<<EOF rather than <<'EOF') has the installing user's
shell expand the body first, so a user-controlled value is baked in as a
literal. Send that into /etc and root later reads or executes a path the
unprivileged user picked: a udev rule carrying
$HOME/.local/share/omarchy/bin/... resolves through a symlink that user
owns, so replacing the symlink gets their code run as root.

Add the static check. A heredoc is flagged when its delimiter is
unquoted, its body contains an install-time expansion (escaped \$VAR does
not count, since that is left for a root daemon to expand at runtime),
and its output reaches /etc, /usr, /opt, /srv, /boot or /var/lib via sudo
tee, sudo dd, a redirect, or an install/cp/mv of the generated scratch
file. Destinations written as variables are resolved from the file's own
assignments.

Sites that genuinely need install-time expansion declare it inline:

  # omarchy:heredoc-expands paths=none -- $servers is a validated IP list

paths= is machine-checked against the expansions the scanner finds to be
path-shaped, so this cannot become a rubber stamp: adding a $HOME/... to
an already-annotated heredoc makes the declaration false and trips the
check again. Path expansions anchored under a root-owned prefix, as in
"/etc/systemd/system/$unit", are correctly not path-shaped.

Annotate the sites the scan reports, each of which expands a scalar: DNS
addresses in omarchy-dns, a literal PAM line in
omarchy-setup-security-fingerprint, kernel cmdline parameters and
usernames in omarchy-upgrade-to-quattro. omarchy-provision-owner expanded
a unit name that was already a constant, so its delimiter is now quoted
and the name hardcoded; the generated unit file is byte-identical.
omarchy-windows-vm declares paths=storage,shared, the only site that
interpolates a user-chosen path.

Fixtures prove non-vacuity in both directions: the write routes other
than a pipe into sudo tee, the shapes that must stay quiet, udev rules
and a shutdown unit taken verbatim from this repository's history, and
the rubber-stamp case where a paths=none annotation on a baked $HOME path
still fails.

2026-08-29 19:23:02 -06:00