ZDDC/zddc/internal/policy/rego.go
ZDDC d3a9ea7ad9 feat(server): federal-mode reference Rego (parent-deny-is-absolute)
Ship a second parity-tested Rego policy that flips the cascade's
leaf-allow-overrides-parent-deny rule for NIST AC-6 conformance.

Standard cascade (existing access.rego, mirrors internal Go evaluator):
  Bottom-up walk; first explicit match wins; deny-first within a level.
  A leaf-level allow CAN override an ancestor's deny. This is the
  cascade's intentional delegation property — a project-owner who
  re-allows a previously-denied collaborator works as expected.

Federal mode (new access_federal.rego):
  Any deny anywhere along the chain is absolute. An allow only matters
  if no level (any depth) has denied the same email. Required by
  NIST AC-6 default expectations: a central admin's deny at the root
  must be unbypassable by a tenant who controls a subtree's .zddc.

Operators run real OPA with this Rego and point ZDDC_OPA_URL at it;
the internal Go evaluator stays on the commercial cascade. The
toggle is "which policy does your OPA evaluate," not a knob inside
zddc-server.

Surfaced via --print-rego flag:

  zddc-server --print-rego               # standard (default)
  zddc-server --print-rego=standard      # same
  zddc-server --print-rego=federal       # AC-6 strict variant

Parity test (federal_parity_test.go) compiles both Regos and asserts:
  * They AGREE on every cascade scenario where no ancestor-deny
    intersects a leaf-allow (most cases).
  * They DISAGREE — by design — on the three scenarios where the
    AC-6 rule differs:
      - "leaf allows what parent denied" → standard allows, federal denies
      - "deep leaf re-allows after middle deny" → same
      - "glob deny at root + specific allow at leaf" → same

Cross-checks the divergence flag explicitly so any future change that
accidentally collapses the two policies fails the test.

Closes the AC-6 row of the federal-readiness gap analysis (now marked
"partially complete" in zddc/README.md — the full bullet would be a
built-in --policy-mode=federal toggle that also flips the in-process
Go evaluator).

Production binary unchanged at 13.1 MB (Rego files embedded as bytes;
OPA library remains test-only).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-05-04 18:05:44 -05:00

46 lines
1.9 KiB
Go

package policy
import _ "embed"
// ReferenceRego is the canonical Rego policy bundled with zddc-server.
// It mirrors the InternalDecider's semantics exactly — every release CI
// run validates parity via parity_test.go (which imports the OPA library
// as a test-only dependency, so the production binary stays OPA-free).
//
// Operators running an external OPA can use this as the starting point
// for their own policy bundle:
//
// zddc-server --print-rego > /etc/opa/policies/zddc-access.rego
//
// Customizations typical for federal deployments:
//
// - Flip the leaf-allow-overrides-parent-deny semantics so parent denies
// are absolute (NIST AC-6 least-privilege posture). For this specific
// case zddc-server ships a parity-tested federal-mode variant; see
// FederalRego and `--print-rego=federal`.
// - Add role-based access via additional input fields (input.user.roles
// populated by the upstream proxy from SAML/OIDC claims).
// - Add time-of-day or IP-range constraints.
// - Emit decision logs in a SIEM-friendly format via OPA's logging
// plugins.
//
//go:embed rego/access.rego
var ReferenceRego string
// FederalRego is the strict-least-privilege variant of ReferenceRego
// where parent denies are absolute (NIST AC-6). Drop-in for federal
// customers who need the AC-6 posture without writing Rego from
// scratch:
//
// zddc-server --print-rego=federal > /etc/opa/policies/zddc-access.rego
//
// The internal Go evaluator does NOT implement these semantics — it
// stays on the commercial cascade. Federal-mode is reachable only by
// running OPA with this policy and pointing ZDDC_OPA_URL at it. See
// zddc/internal/policy/rego/access_federal.rego for the policy itself
// and federal_parity_test.go for the divergence-test fixtures (cases
// where federal-mode and commercial-mode disagree, asserting each gives
// the expected verdict).
//
//go:embed rego/access_federal.rego
var FederalRego string