6c95933775
Security fixes landed without updating the security-model docs; bring them current as present-tense invariants: - security.md: matrix identities are public / cross-agent-readable via GetAgentMeta while the token stays private; name validation extends to GetAgentMeta; the nix-build blast radius has a network dimension (hive-ci netns) alongside the 0600 token policy. - boundary.md: the core dashboard /api has no app-layer auth — protection is the gateway plus network isolation; stated as a standing invariant. - ci.md: hive-ci runs in its own private netns behind the bridge, reaches the forge via the gateway, and cannot reach host-loopback (dashboard/forge port). - knowledge.md: /knowledge excludes .git via tmpfs so the core token in .git/config isn't readable by agents. Refs #2308, #2310, #2313.
95 lines
4.6 KiB
Markdown
95 lines
4.6 KiB
Markdown
# The operator/agent boundary
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Design rationale for hyperhive's two-principal trust model. The
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_implementation_ work — container network isolation, the unifying
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gateway, core-daemon privsep — is tracked as `area:ops` issues on
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the forge.
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The operator/agent boundary is now technically enforced, not just a
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convention. Containers run in private netns (network isolation is
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always on), the gateway proxies all operator-facing traffic, and
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`hive-c0re` runs as the unprivileged `hive-core` user. All three
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`area:ops` pillars — network isolation, the gateway, and privsep —
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are complete and active.
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## Two principals, two paths
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- **Operator** — reaches every UI (the dashboard + every
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per-agent page) through the gateway, on one origin.
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Operator-authority actions (approve / deny, answer-as-operator,
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lifecycle POSTs) are served by the core daemon and only
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reachable via the gateway.
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- **Agent** — speaks only for itself, only over its per-agent
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unix socket. The socket's identity _is_ the agent (see
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`docs/conventions.md`, "identity = socket"). An agent must not
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be able to reach the core daemon's HTTP surface, another
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agent's socket, or another agent's web UI.
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## Design rule
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**Operator-authority actions never get a per-agent-socket entry
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point.** They live on the core backend.
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Worked example — answering an operator-targeted question is a
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`POST /answer-question/{id}` on the core dashboard, _never_ an
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`AgentRequest` variant. If it were a per-agent-socket request, an
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agent could `curl` its own socket and spoof an operator answer.
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The per-agent web UI POSTs cross-origin to the core for these
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(see the inline-answer feature — the loose-ends section on each
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agent page).
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## Why network isolation is the load-bearing step
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Without network isolation, containers share the host network namespace
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and can reach `localhost:<core-port>`, the dashboard, and every other
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agent's web port — the operator/agent split is on the honour system and
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every boundary claim above is aspirational. Network isolation is what
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makes the boundary _real_; the gateway and privsep are ergonomics and
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defence-in-depth layered on top.
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Network isolation is now complete and always on: every agent container
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runs in a private netns behind the hive bridge. The shared-netns mode
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was removed. See `docs/network.md`.
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Concretely, the core daemon's dashboard `/api` carries **no
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application-layer authentication** — operator-authority routes are served
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unauthenticated at the HTTP layer. Their protection is entirely (a) the
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gateway, which fronts all operator traffic and is where operator auth lives,
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and (b) network isolation, which keeps agents — and `hive-ci`'s untrusted PR
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builds — off host-loopback so nothing can reach `127.0.0.1:<dashboard_port>`
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directly. This is deliberate given the load-bearing role of network isolation
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above, but it is a standing invariant: the `/api` must never be bound to a
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non-loopback address or exposed outside the gateway, and every new
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operator-authority route inherits that assumption. `hive-ci` is treated like an
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agent for this purpose — it runs untrusted PR code and is netns-isolated for
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the same reason.
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The `area:ops` issues followed this sequencing:
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1. **Gateway** — pure ergonomics win, unblocks same-origin (lets the
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cross-origin CORS shim on `/answer-question/{id}` go away), no
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behavioural risk. An nginx nixos-container now sits in front of all
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surfaces; per-agent UIs are proxied under `/agent/<name>/`.
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2. **Network isolation** — the load-bearing step that turns the
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honour-system split into an enforced boundary. **Complete** —
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always-on, unconditional; the shared-netns mode was removed.
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3. **Privsep** — defence in depth on the core process; `hive-c0re`
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runs as the unprivileged `hive-core` user and delegates root
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operations to `hive-priv`, a narrow socket-activated helper. See
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[`docs/security.md`](security.md) for the privilege boundary table.
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### hive-priv socket activation
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`hive-priv` is **always** socket-activated by the `hive-priv.socket`
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systemd unit. The unit binds `/run/hive/priv.sock` with
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`SocketGroup=hive-core` and mode `0660` and passes the ready listener
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to the helper as fd 3 (`LISTEN_FDS`). The helper requires this and
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bails if it isn't socket-activated — there is intentionally no
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self-bind fallback.
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Dropping the old fallback removed a dev/prod divergence: when
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`hive-priv` bound the socket itself it created the file owned by
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root's primary group rather than `hive-core`, so a `hive-core` client
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couldn't connect the way the socket unit's `SocketGroup` grant
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intends. Requiring socket activation everywhere means dev and prod
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take the exact same path and the group grant always holds.
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