feat(nix): issue each hive's CA under a swarm root CA

Cross-hive trust was O(n²) hand-pinning: every hive had to name every
peer's CA. A swarm root makes it O(1) — trust the root once and every
present and future peer validates.

The root is generated by a new `swarm-ca` unit on a single-host swarm
and operator-provided otherwise; `swarm.ca.autoConfigure` picks between
them and derives its default from `swarm.peers` being empty, so "all on
one host" is read off the deployment rather than remembered. Both modes
produce the same artifacts in the same places, so splitting hosts later
is moving the service dirs, not switching code paths. The root key never
enters the nix store, and the root is never regenerated automatically —
replacing it invalidates every peer at once.

Each hive CA carries `nameConstraints` pinned to that hive's domain, so
a leaked hive CA can only mint names inside its own subdomain, enforced
by verifiers rather than by convention.

`ca.pem` was serving as both the issuer and the anchor consumers trust;
those are the same file only while it is self-signed. openssl will not
terminate a chain at a trusted cert that isn't self-signed (rustls and
Go will), so the promotion would have broken some consumers and not
others. `hive-tls-ca` now also writes `trust-bundle.pem` — the hive CA
plus whatever it is rooted at — and every anchor consumer reads that:
agents, the CI and forge containers, and the peer-config recipe. On a
hive with no swarm root the bundle is just that CA, so nothing consuming
it needs a mode to branch on.
This commit is contained in:
atlas 2026-08-05 14:33:49 +02:00 committed by mara
commit 06710e83b4
8 changed files with 366 additions and 33 deletions

View file

@ -194,9 +194,11 @@ Mutual exclusion: `tls.certDir` set together with `tls.acme.enable = true` fails
On by default, and listens on `httpsPort` (default 443) on every vhost beside the plain-http `port` (default 80).
The anchor is a **host-held hive CA**, not a bare self-signed leaf. A host service (`hive-tls-ca.service`, from the `hive-tls` module) generates a long-lived CA (`services.hyperhive.tls.caValidityDays`, default ~20y) under `services.hyperhive.tls.stateDir` (default `/var/lib/hive-tls`), then signs a gateway **leaf** (`leafValidityDays`, default ~10y) with it. The leaf dir is bind-mounted read-only into the gateway container at `/run/hive-ca`; an in-container import unit copies the leaf into nginx's state dir (`/var/lib/hive-gateway/tls/{cert,key}.pem`) with the owner/mode nginx needs.
The issuer is a **host-held hive CA**, not a bare self-signed leaf. A host service (`hive-tls-ca.service`, from the `hive-tls` module) generates a long-lived CA (`services.hyperhive.tls.caValidityDays`, default ~20y) under `services.hyperhive.tls.stateDir` (default `/var/lib/hive-tls`), then signs a gateway **leaf** (`leafValidityDays`, default 30d) with it. The leaf dir is bind-mounted read-only into the gateway container at `/run/hive-ca`; an in-container import unit copies the leaf into nginx's state dir (`/var/lib/hive-gateway/tls/{cert,key}.pem`) with the owner/mode nginx needs.
**Why a CA, not a bare leaf**: a bare self-signed leaf is its own trust anchor, so every regeneration is a new anchor every consumer must re-trust — and a runtime-generated, in-container leaf can't be wired into an agent's build-time trust store at all. With a stable CA, agents and federation peers trust the CA *once* (`ca.pem`); leaf rotation never re-breaks them.
**Why a CA, not a bare leaf**: a bare self-signed leaf is its own trust anchor, so every regeneration is a new anchor every consumer must re-trust — and a runtime-generated, in-container leaf can't be wired into an agent's build-time trust store at all. With a stable CA, agents and federation peers trust it *once*; leaf rotation never re-breaks them.
**What consumers trust**: `trust-bundle.pem` in the same state dir, not `ca.pem`. The hive CA is itself issued under the swarm root ([`swarm.md`](swarm.md#swarm-ca) has the hierarchy), and an intermediate is not a chain a verifier can terminate at — so the bundle carries the hive CA plus whatever it is rooted at. nginx is handed the leaf with the hive CA appended for the same reason. Everything that trusts the hive's TLS reads the bundle: agents (via `security.pki.certificateFiles`), the CI and forge containers, and a federating peer.
**Why on by default**: matrix-dart-sdk (FluffyChat's SDK) hardcodes `https://<host>/.well-known/matrix/client` for homeserver discovery and refuses to fall back to plain http. Without TLS the browser client cannot bootstrap.
@ -204,7 +206,7 @@ The anchor is a **host-held hive CA**, not a bare self-signed leaf. A host servi
**Rotation**: `hive-tls-ca.service` is idempotent — it re-signs the leaf when it is missing or within 30 days of expiry, always under the same CA (so consumer trust is undisturbed). The CA itself is regenerated only if missing or already expired. To force a leaf rotation, delete `gateway.pem` under the state dir and restart the unit, then reload `nginx`.
**Cert prompts**: browsers still warn once per host until the hive CA is added to the browser/OS trust store (the CA, not the leaf, is the thing to trust). Agent trust of the CA is wired separately (see the agent-trust work for `/run/hive-ca`).
**Cert prompts**: browsers still warn once per host until the hive's `trust-bundle.pem` is added to the browser/OS trust store (an anchor, not the leaf, is the thing to trust). Agent trust is wired separately (see the agent-trust work for `/run/hive-ca`).
### Operator-provided cert (`tls.certDir`)