Firewall Mode permits only what ctrld resolved through its own listener.
The API transport resolves api.controld.com through the OS nameservers and
falls back to hardcoded addresses, so nothing ever teaches the allowlist
about it and ctrld's own block-all filters deny its control-plane socket.
The upgrade download server has the same shape: performUpgrade spawns a
detached child process, and the WFP filters carry no process condition, so
the service blocks its own upgrade.
Permit both permanently, at startup and on reload. For the API that means
the resolved addresses and the transport's direct fallbacks - the fallbacks
are what it dials when DNS is unusable, which is the state a blocked ctrld
is in. For the download server only the fallback IP is needed, since its
hostname lookup does go through the listener and is learned.
APIDomain/APIEndpointIPs are exported so the permitted set and the dialed
set cannot drift apart.
Call initPlatformFirewall on reload even when enforcement is already up.
AddPermanent fires no change callback, so an address permitted by a reload
reached memory only while the platform never heard about it. Each
platform's re-entry is a refresh: Windows reinstalls the permanent filters
it is missing, macOS returns early.
Also keep every dial attempt in the transport's error. It returned only the
last stage, an unroutable IPv6 address reporting "no route to host", hiding
the IPv4 WSAEACCES that named the real cause. The direct IPs are still
always dialed, so the API stays reachable without DNS; only a duplicate
dial of an address the resolver already returned is dropped.
Firewall Mode only permits what ctrld resolved, so an approved service addressed
by literal IP - with no DNS lookup to observe - is unreachable, and the only
workaround was turning the mode off. The API now sends the effective per-org list
in destination_ips of every resolver-config response.
Apply it as a set rather than as additions: each refresh replaces the previous
snapshot, so an entry added upstream takes effect and one removed upstream stops
bypassing enforcement. This happens inside the refresh handler before its early
returns, so scheduled and forced refreshes both carry it, and without a ctrld
reload. Entries carry no TTL and survive the allowlist flushes that follow a
profile or network change.
Track what the API asked for separately from what pf/WFP accepted, because
mirroring can fail and the next refresh - carrying an identical list - would
compute no delta to retry. The applied snapshot advances only on success, and the
difference is retried by the next refresh and by a reconcile every 5 minutes,
reported meanwhile as allowed_destinations_pending. Enforcement coming up
replaces the whole set rather than adding to it: the macOS table is a persist
table that can still hold what a previous run put there. Enforcement is versioned
by a generation advanced under the same lock the mirror is called with, so a
maintenance worker outliving its run cannot reinstall permits into enforcement
that is gone.
macOS keeps the set in a second pf table, <ctrld_allowed_dst>; Windows in
per-entry WFP permit filters in their own map - apart from the DNS-resolved
entries so a flush of those leaves them installed. Linux is unchanged, the mode
already fails open there, and devices with Firewall Mode off are unaffected.
Lookups binary search sorted per-family address ranges, so the per-connection hot
path stays flat at ~40ns rather than growing with the list. Addresses are logged
at debug level only: the list is organization network topology, and Info-level
logs are persisted and travel in support bundles.
Indirect the refresh's fetch and split its handler out of the fetch loop so both
refresh paths are driven end to end in tests without an API server.
Cuong Manh Le