swarm-bao: give the store forwarder's OIDC reader its own bao identity

`swarm-bao-forwarder-oidc` fetches the store container's collector secret,
one path, and was the last reader still logging in with
`deploy.bao.clientCertFile`: the hive's own leaf, whose policy reads every
agent's credentials, the hive's tree and every service's OIDC secret. The
four-way split gave grafana's and the swarm collector's readers leaves of
their own and left this one behind.

It now holds `forwarder-oidc.pem`, minted by `swarm-bao-pki`, and logs in
under the `swarm-forwarder-oidc` cert-auth role, whose policy reads
`secret/data/swarm/services/<store forwarder client id>/oidc/client` and
nothing else. The role is written by `swarm-bao-forwarder-oidc-policy`
from the bootstrap token, which gains the two grants that unit calls, and
the reader is ordered after it. The subject is reserved as a hive name. A
store host whose pair is null is refused at eval rather than falling back
to the hive's leaf.

The hive's own role and `client.pem` are untouched; nothing is revoked.
This commit is contained in:
atlas 2026-09-24 17:25:34 +02:00 • committed by mara
commit 92e1909caf
9 changed files with 229 additions and 47 deletions

View file

@ -98,7 +98,7 @@ collector this unit never reaches.
The **secret store's own** collector — the forwarder inside the `swarm-bao`
container — needs a delivery step too, and it takes the same route with one
principal of its own: `swarm-bao-forwarder-oidc.service` reads
`swarm/services/<client-id>/oidc/client` under this host's certificate and
`swarm/services/<client-id>/oidc/client` under a leaf of its own and
lands it in the container's tree, where `LoadCredential` hands it to the
collector. The client id is its own
(`services.hyperhive.swarm.bao.otel.clientId`), registered by
@ -284,8 +284,10 @@ fourth in both directions. It renders unconditionally, because the export it
authenticates has no unauthenticated mode to degrade into — and it orders
itself **after** `container@swarm-bao`, because the store it reads runs in the
container it delivers into. Nothing circular sits behind that: the identity it
logs in with is this host's static `swarm-bao-pki` leaf, not anything the store
mints.
logs in with is the static `forwarder-oidc.pem` leaf `swarm-bao-pki` signs, not
anything the store mints. With no leaf it has no fallback, so `swarm-bao.nix`
refuses the build and names `deploy.bao.forwarderOidcClientCertFile` /
`forwarderOidcClientKeyFile`.
A service's secret is one value for the whole swarm rather than one per hive, so
it lives under the `services` prefix, and a hive's read policy grants that prefix
@ -295,9 +297,9 @@ there is nothing to scope the grant to. A hive's **own** leaf can therefore read
every swarm service's client secret, and that's stated in
`swarm-secret-client`'s `policy` module beside the grant itself.
⚠️ **The readers no longer present it.** Four units used to log in with
⚠️ **The readers no longer present it.** Five units used to log in with
`deploy.bao.clientCertFile`, which is the hive's own leaf, and bao identifies a
principal by the subject of the certificate it presents — so four readers behind
principal by the subject of the certificate it presents — so five readers behind
one leaf were one principal holding the union of their needs. Each now holds a
leaf of its own, and a policy naming only the path that unit reads. See
[per-principal identities](#per-principal-identities) below.
@ -326,31 +328,34 @@ else a hive needs does.
### Per-principal identities
Bao matches a cert-auth role on the certificate's subject, so a certificate is an
identity and sharing one merges the identities. These four units read one path
identity and sharing one merges the identities. These five units read one path
each and each holds a leaf, a role and a policy of its own:
| unit | option pair under `deploy.bao.` | reads |
| ------------------------ | -------------------------------------------------------- | -------------------------------------------------- |
| `swarm-bao-matrix-token` | `matrixTokenClientCertFile` / `matrixTokenClientKeyFile` | `swarm/hives/<hive>/matrix/appservice-token` |
| `swarm-bao-queue-agent` | `queueAgentClientCertFile` / `queueAgentClientKeyFile` | `swarm/hives/<hive>/queue/agent` |
| `swarm-bao-grafana-oidc` | `grafanaOidcClientCertFile` / `grafanaOidcClientKeyFile` | `swarm/services/<grafana client id>/oidc/client` |
| `swarm-bao-otel-oidc` | `otelOidcClientCertFile` / `otelOidcClientKeyFile` | `swarm/services/<collector client id>/oidc/client` |
| unit | option pair under `deploy.bao.` | reads |
| -------------------------- | ------------------------------------------------------------ | -------------------------------------------------------- |
| `swarm-bao-matrix-token` | `matrixTokenClientCertFile` / `matrixTokenClientKeyFile` | `swarm/hives/<hive>/matrix/appservice-token` |
| `swarm-bao-queue-agent` | `queueAgentClientCertFile` / `queueAgentClientKeyFile` | `swarm/hives/<hive>/queue/agent` |
| `swarm-bao-grafana-oidc` | `grafanaOidcClientCertFile` / `grafanaOidcClientKeyFile` | `swarm/services/<grafana client id>/oidc/client` |
| `swarm-bao-otel-oidc` | `otelOidcClientCertFile` / `otelOidcClientKeyFile` | `swarm/services/<collector client id>/oidc/client` |
| `swarm-bao-forwarder-oidc` | `forwarderOidcClientCertFile` / `forwarderOidcClientKeyFile` | `swarm/services/<store forwarder client id>/oidc/client` |
The first two exist **per hive**, because the path they read carries a hive
name and every hive runs its own reader. Their subjects are
`<deploy.bao.matrixTokenCommonNamePrefix>-<hive>` and
`<deploy.bao.queueAgentCommonNamePrefix>-<hive>`; `swarm.nix` reserves both
composed spellings as hive names, so nobody can name a hive into another hive's
role. The other two read a path that names a swarm service rather than a hive, so
one role each is enough and their subjects are the flat
`deploy.bao.grafanaOidcCommonName` and `deploy.bao.otelOidcCommonName`.
role. The other three read a path that names a swarm service rather than a hive,
so one role each is enough and their subjects are the flat
`deploy.bao.grafanaOidcCommonName`, `deploy.bao.otelOidcCommonName` and
`deploy.bao.forwarderOidcCommonName`.
On a host that mints its own PKI, `glue-bao-tls.nix` signs all four and defaults
all eight options, and there is nothing to do. Elsewhere you issue each leaf from
On a host that mints its own PKI, `glue-bao-tls.nix` signs all five and defaults
all ten options, and there is nothing to do. Elsewhere you issue each leaf from
that CA out of band and name it here — one file per principal rather than one file
shared by four, which is the whole of what this buys.
shared by five, which is the whole of what this buys.
Forgetting one of the eight elsewhere isn't a quiet degrade. Three of the four
On a host without the store, where the fifth never runs, forgetting one of the
other eight isn't a quiet degrade. Three of the four
readers used to render only where their leaf existed, so a hand-configured
remote-store hive that named the hive's own `clientCertFile` and missed a
principal's pair just lost that unit; `swarm-grafana.nix` was alone in refusing