fix(ci): harden workflow token scope and download integrity (#39)

Security audit of .github/workflows found a script-injection vector in the
release workflow, over-broad token grants on non-publishing jobs, and
downloaded tooling/manifests executed without integrity checks.

- release: pass the tag/dispatch input through env instead of interpolating
  it into the validation script; default workflow permissions to contents:read
- build-main/build-gateway: grant write scopes only to the build job
- _build-image/codeql: stop persisting checkout credentials
- ci/release: verify actionlint, hadolint and git-cliff against pinned SHA-256s
- ci-manifests/e2e: verify upstream CRD manifests against versions.env pins
- e2e: redact token material before uploading cluster diagnostics
- docs: add workflow-security.md with controls, audit record and residual
  repository-setting recommendations

Co-authored-by: SREDevOpsAgents <agents@sredevops.org>

docs/README.md

@@ -15,6 +15,7 @@ gets a DSH Web container running before anything else.
 | [examples.md](examples.md) | The example contract: required layout, manifest rules, exposure variants, components and image naming, scripts, docs, and how to add a new example. |
 | [gitflow.md](gitflow.md) | Branches, protected `main`, squash merges, Conventional PR titles, required CI checks, release branches, hotfixes and the one-time GitHub settings checklist. |
 | [versioning.md](versioning.md) | Release identity (`DSH ref` + optional `-rN`), the current identity `dsh-v0.2.1-rc.5`, why identities are immutable, channels, compatibility matrix, bumping pins, the release checklist, rollback, git-cliff and digest pinning. |
+| [workflow-security.md](workflow-security.md) | GitHub Actions security posture: least-privilege tokens, pinned actions, untrusted-input handling, download integrity checks, artifact hygiene, the latest audit record and residual repository-setting recommendations. |
 
 ## Project skills
 

docs/workflow-security.md

@@ -0,0 +1,69 @@
+# Workflow security (GitHub Actions)
+
+The CI/CD surface lives entirely in [`.github/workflows/`](../.github/workflows/)
+and runs on GitHub-hosted runners. This page describes the controls those
+workflows enforce and records the most recent audit. They complement the threat
+notes in [SECURITY.md](../SECURITY.md) and the release procedure in
+[versioning.md](versioning.md).
+
+## Controls
+
+| Control | Where | What it does |
+| --- | --- | --- |
+| Least-privilege tokens | Every workflow | A top-level `permissions:` block defaults to read-only; `packages: write`, `contents: write`, `id-token: write` and `attestations: write` are granted only to the jobs that publish images, attestations or releases. |
+| Pinned actions | Every `uses:` | Third-party actions and reusable workflows are pinned to a full 40-character commit SHA (the version is kept in the trailing comment). Dependabot updates the pins weekly. The only unpinned reference is the in-repository `./.github/workflows/_build-image.yaml`. |
+| No privileged untrusted triggers | Trigger blocks | No workflow uses `pull_request_target` or `workflow_run`. PR-triggered workflows run untrusted code with a read-only token and no secrets. |
+| Untrusted input is data | `release.yaml` | The release tag (from a tag push or `workflow_dispatch` input) is passed through `env:` and read as a shell variable; it is never interpolated into a `run:` script, so metacharacters in a tag name cannot execute. |
+| Checkout credential hygiene | Checkout steps | `persist-credentials: false` is set wherever the job does not need to push. The changelog job keeps credentials because it pushes a branch and opens a PR with `GITHUB_TOKEN`. |
+| Download integrity | `ci.yaml`, `release.yaml` | actionlint, hadolint and git-cliff are downloaded with `curl --proto '=https'` and verified against a pinned SHA-256 with `sha256sum -c` before execution. |
+| Cluster manifest integrity | `ci-manifests.yaml`, `e2e-kind.yaml` | The agent-sandbox and Gateway API release manifests are downloaded and checked against the `*_MANIFEST_SHA256` pins in [versions.env](../versions.env) before `kubectl apply`. |
+| Log and artifact hygiene | `ci-image.yaml`, `e2e-kind.yaml` | Pod logs are truncated and token material is redacted before logs are printed or diagnostic files are uploaded as artifacts. |
+| Supply-chain monitoring | Repository settings | Dependabot (GitHub Actions, pip, Docker), CodeQL advanced setup and the dependency-review action run on every applicable change. CODEOWNERS covers the whole repository, including `.github/workflows/`. |
+
+## Maintaining the pins
+
+- The tool versions and their SHA-256 digests live together in the install step
+  (`ACTIONLINT_SHA256`, `HADOLINT_SHA256`, `GIT_CLIFF_SHA256`); update both
+  values when bumping a version.
+- Control-plane versions are in `versions.env`; update
+  `AGENT_SANDBOX_MANIFEST_SHA256` or `GATEWAY_API_MANIFEST_SHA256` together with
+  the corresponding version, otherwise CI fails the digest check by design.
+- GitHub Actions pins are updated by Dependabot; never replace a SHA with a tag.
+
+## Audit record (2026-10-30)
+
+Scope: all 11 workflows under `.github/workflows/`, plus `.github/CODEOWNERS`
+and `.github/dependabot.yml`. Findings are grouped by the categories in
+GitHub's [Secure use reference](https://docs.github.com/en/actions/reference/security/secure-use).
+
+| # | Category | File | Severity | Finding | Status |
+| --- | --- | --- | --- | --- | --- |
+| 1 | Script injection | `release.yaml` | High | Tag name / dispatch input interpolated into a privileged `run:` block | Fixed: passed through `env` |
+| 2 | Token permissions | `release.yaml` | Medium | `meta` and `tests` inherited workflow-level write scopes | Fixed: workflow default is `contents: read` |
+| 3 | Token permissions | `build-main.yaml`, `build-gateway.yaml` | Low | `meta` inherited `packages`/`id-token`/`attestations` write | Fixed: workflow default is `contents: read` |
+| 4 | Checkout | `_build-image.yaml` | Low | Checkout persisted the token in `.git/config` | Fixed: `persist-credentials: false` |
+| 5 | Checkout | `codeql.yml` | Low | Checkout persisted the token in `.git/config` | Fixed: `persist-credentials: false` |
+| 6 | Supply chain | `ci.yaml` | Medium | actionlint and hadolint were executed without a checksum | Fixed: pinned SHA-256 verified before install |
+| 7 | Supply chain | `release.yaml` | Medium | git-cliff was executed without a checksum in the release job | Fixed: pinned SHA-256 verified before install |
+| 8 | Supply chain | `ci-manifests.yaml`, `e2e-kind.yaml` | Medium | Upstream CRD/controller manifests applied without integrity checks | Fixed: pinned SHA-256 in `versions.env` |
+| 9 | Secret hygiene | `e2e-kind.yaml` | Low | Raw gateway logs uploaded in a 7-day artifact | Fixed: `token=` values redacted |
+| 10 | Repository controls | Repository settings | Low | No environment approval gate on publishing; single CODEOWNER | Recommendation: see below |
+
+Checked and clean: no `pull_request_target`/`workflow_run`, no self-hosted
+runners, all third-party actions pinned, PR workflows read-only, no secrets in
+workflow files, no secret interpolation into scripts.
+
+## Residual recommendations (repository settings)
+
+These cannot be enforced from workflow files alone:
+
+- Add a protected `release` environment with required reviewers and attach it to
+  the `build-main`, `build-gateway` and `publish-release` jobs. This requires the
+  environment to exist in repository settings first, so it is intentionally not
+  wired into the workflow yet.
+- Keep "Allow GitHub Actions to create and approve pull requests" limited to
+  creating PRs (the changelog job needs create, not approve).
+- Require review from Code Owners for `.github/workflows/` and add a second
+  owner so workflow changes are never single-person.
+- Optionally run OpenSSF Scorecard on a schedule for continuous checks on these
+  controls.