`>|` is a plain redirect with noclobber overridden, not a redirect followed by a pipe. command_destinations detached `>` from its target before looking at the bar, so the target read as `|` and the privileged path behind it was never examined: `cat <<EOF >| /etc/udev/rules.d/99-x.rules` with `$HOME` in the body produced no finding at all, while the same write through `>` produced one.
Normalizing `>|` to `>` alongside the existing `>>` handling closes it. The fixture fails without the normalization.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
The failure advice printed a ready-to-paste annotation with the scan's
verdict already filled in, so the shortest way past the check was to copy
back what it had just concluded. That is worst exactly where the scan is
weakest: a path it cannot follow through a variable reads as an ordinary
value, and the annotation it offers for that case is paths=none.
Print the annotation with the path list left blank and say why the author
has to fill it in. The scan's own reading stays in the report above it, so
nothing diagnostic is lost.
Review of the previous commits turned up four places where the predicates
and their tests disagreed with the tools they are modelling, each checked
against udevadm verify, systemd-analyze verify and visudo -cf rather than
against reading of the sources.
An empty ExecStop= resets the list, so a unit an administrator neutralised
that way runs nothing at shutdown and is no longer ours to remove; the
predicate now tracks the last state instead of returning on the first home
path it sees. A file whose last line ends in a backslash still carries a
live directive for systemd, so the pending logical line is emitted at EOF;
udev ignores such a line and sudo rejects the file outright, so this costs
those two nothing. The scanner's taint pass now reads += appends, which its
own comment already promised: the value of an append is no use, but a name
that reaches a user root through one has to be judged on it.
Two regression guards passed against the implementations they were written
for. The udev continuation fixture put the whole RUN+= below the comment, so
it matched whether or not the pending half was carried across; the split now
falls inside the RUN+= value. The sudoers one kept its file on the strength
of a spec above the comment, so it could not fail either; the hand-written
spec now sits below. Both fail against a mutant that discards the pending
line. The comment above the second also claimed a continued comment stays a
comment, which visudo contradicts.
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.
Ryan Hughes