Switch DNS providers without a password prompt (#7472)

* Switch DNS providers without a password prompt

The network panel and the menu run omarchy-dns from a process with no
terminal, so require_root reached for pkexec and put a polkit password
prompt in front of what is meant to be a one-click toggle.

Grant %wheel passwordless sudo for the three stock providers and take
that path whenever the grant covers the invocation. Custom stays out of
the grant: it points the machine at servers the caller supplies, and it
already runs in a terminal that can ask.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Pick the elevation path without asking sudo

The `sudo -n -l` probe answered the wrong question. It reports whether a
command is permitted, not whether it is passwordless, and the %wheel rule
every Omarchy install ships permits everything -- `sudo -n -l /usr/bin/rm
-rf /tmp/x` exits 0. So the probe passed for Custom too, and the exec
below it ran `sudo -n`, which fails outright with no terminal and no way
back to pkexec.

Decide from what the sudoers rule actually says instead: sudo when there
is a terminal to type into, or when the resolved path and the provider
are both ones the rule names. Everything else keeps going through polkit.

Pin a root-owned PATH once elevated, too. `omarchy dev link` puts a
user-writable checkout ahead of sudo's secure_path for every command, so
a passwordless grant on a script that resolves nmcli, tee, and install
through PATH would otherwise hand root to whoever can write there.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Keep users outside %wheel on the polkit path

The rule grants %wheel, so path and provider alone do not mean sudo will
take it. A user outside the group was sent to sudo anyway, and with no
terminal to answer the prompt that is a dead end -- polkit at least
offers to authenticate as somebody else.

Two holes in the test alongside it: it accepted any file containing the
expected rule, so a second, argument-free line would have widened the
grant unnoticed, and run as root it would have sailed past the stubs and
rewritten the host's own DNS config.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

* Elevate the system install, whatever copy was invoked

The rule names /usr/bin/omarchy-dns, so a dev-linked checkout handed sudo
a path nothing could match and fell back to a polkit prompt. Re-exec the
packaged path instead: the privileged half is the system install
everywhere, the grant matches everywhere, and the path comparison and the
PATH pinning that existed to work around the checkout both go away.

Dev-linked checkouts run their own unprivileged half and the installed
one as root, which is the trade for not carrying a second code path.

---------

Co-authored-by: Omabot <david@hey.com>
Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

test/shell.d/dns-sudoers-test.sh

@@ -0,0 +1,97 @@
+#!/bin/bash
+
+set -euo pipefail
+
+source "$(dirname "$0")/base-test.sh"
+
+dns="$ROOT/bin/omarchy-dns"
+sudoers_file="$ROOT/etc/sudoers.d/omarchy-dns"
+rule='%wheel ALL=(root) NOPASSWD: /usr/bin/omarchy-dns Cloudflare, /usr/bin/omarchy-dns Google, /usr/bin/omarchy-dns DHCP'
+
+# Exactly one rule, matched whole. A second line -- or the same command with its
+# arguments dropped, which sudoers reads as "any arguments" -- would widen the
+# grant while leaving this line in place.
+rules=$(grep -vE '^[[:space:]]*(#|$)' "$sudoers_file")
+[[ $rules == "$rule" ]] ||
+  fail "dns sudoers file carries exactly the stock-provider rule and nothing else" "got: $rules"
+
+if command -v visudo >/dev/null; then
+  visudo -cf "$sudoers_file" >/dev/null || fail "dns sudoers rule parses"
+fi
+
+grep -Fx 'PACKAGED_PATH=/usr/bin/omarchy-dns' "$dns" >/dev/null ||
+  fail "omarchy-dns elevates the path the sudoers rule names"
+
+# sudo -l answers whether a command is permitted, not whether it is
+# passwordless, and Omarchy ships a blanket %wheel rule that permits
+# everything. A probe built on it sends Custom into `sudo -n`, which fails
+# outright instead of falling through to pkexec.
+! grep -E '^[[:space:]]*[^#[:space:]].*sudo -n -l' "$dns" >/dev/null ||
+  fail "omarchy-dns does not decide elevation with a sudo -l probe"
+
+pass "dns sudoers rule is scoped to the stock providers"
+
+# require_root returns immediately for root, so the stubs below would not stand
+# between the script and the host's real NetworkManager and resolved config.
+if (( EUID == 0 )); then
+  pass "running as root; skipping the elevation checks, which would rewrite this machine's DNS"
+  exit 0
+fi
+
+test_tmp=$(mktemp -d)
+trap 'rm -rf "$test_tmp"' EXIT
+
+stub_bin="$test_tmp/bin"
+mkdir -p "$stub_bin"
+
+# Both stubs stand in for the exec at the end of require_root, so the DNS writes
+# below it never run, and neither real sudo nor real pkexec is reached.
+for command in sudo pkexec; do
+  cat >"$stub_bin/$command" <<SH
+#!/bin/bash
+printf '$command %s\n' "\$*" >"\$ELEVATION_LOG"
+SH
+  chmod +x "$stub_bin/$command"
+done
+
+# The rule is %wheel-scoped, so group membership decides the route as much as
+# the provider does. Stub id rather than reading the real groups: the suite has
+# to give the same answer on a build user outside wheel.
+cat >"$stub_bin/id" <<'SH'
+#!/bin/bash
+[[ ${1:-} == -nG ]] || exec /usr/bin/id "$@"
+printf '%s\n' "${STUB_GROUPS-users wheel}"
+SH
+chmod +x "$stub_bin/id"
+
+elevation_for() {
+  : >"$test_tmp/elevation"
+  ELEVATION_LOG="$test_tmp/elevation" \
+  PATH="$stub_bin:$PATH" \
+    bash "$dns" "$1" </dev/null >/dev/null
+  cat "$test_tmp/elevation"
+}
+
+for provider in Cloudflare Google DHCP; do
+  elevation=$(elevation_for "$provider")
+  [[ $elevation == "sudo /usr/bin/omarchy-dns $provider" ]] ||
+    fail "omarchy-dns takes the passwordless sudo grant for $provider without a terminal" "got: $elevation"
+done
+
+pass "omarchy-dns elevates the stock providers through sudo, not polkit"
+
+# A dev-linked checkout elevates the packaged path like everyone else, rather
+# than handing sudo a path no rule can name and losing the grant.
+dev_linked=$(OMARCHY_PATH="$test_tmp/checkout" elevation_for Cloudflare)
+[[ $dev_linked == "sudo /usr/bin/omarchy-dns Cloudflare" ]] ||
+  fail "omarchy-dns elevates the system install wherever OMARCHY_PATH points" "got: $dev_linked"
+
+custom=$(elevation_for Custom)
+[[ $custom == "pkexec /usr/bin/omarchy-dns Custom" ]] ||
+  fail "omarchy-dns leaves Custom on the polkit path, since no sudoers rule covers it" "got: $custom"
+
+non_wheel=$(STUB_GROUPS="users" elevation_for Cloudflare)
+[[ $non_wheel == "pkexec /usr/bin/omarchy-dns Cloudflare" ]] ||
+  fail "omarchy-dns leaves a user outside %wheel on the polkit path, since the rule cannot match them" "got: $non_wheel"
+
+pass "omarchy-dns falls back to polkit wherever the grant does not reach"