fix: remediate latest zizmor findings, fix supplying zizmor config

The current version of Zizmor finds some potential template injection
issues. We can fix these by indirecting via the `env`, or in a couple of
cases by adding ignore comments where we can't really fix the issue.

Something happened to break our config discovery. What we do is download
a default config file from this repo, write it to a temporary file, set
that file's path as `ZIZMOR_CONFIG`, and then pass this as `--config` if
it's set. Possibly as the result of a version bump, Zizmor started
handling `ZIZMOR_CONFIG` differently. An empty string here is treated as
a file to search for, which doesn't work, and so we get errors.

A fix for this last one is to use a different variable name that doesn't
collide with the one Zizmor itself is using. Rename to
`ZIZMOR_CONFIG_PATH` accordingly.

Author: iainlane

.github/workflows/reusable-zizmor.yml

@@ -355,9 +355,9 @@ jobs:
             echo "always-use-default-config is set. Using default config."
           fi
 
-          ZIZMOR_CONFIG="${{ runner.temp }}/zizmor.yml"
+          ZIZMOR_CONFIG_PATH="${{ runner.temp }}/zizmor.yml"
           if [ -n "${DEFAULT_ZIZMOR_CONFIG_DOWNLOADED}" ]; then
-            echo "zizmor-config=${ZIZMOR_CONFIG}" | tee -a "${GITHUB_OUTPUT}"
+            echo "zizmor-config=${ZIZMOR_CONFIG_PATH}" | tee -a "${GITHUB_OUTPUT}"
           fi
 
       - name: Setup UV
@@ -376,7 +376,7 @@ jobs:
 
       - name: Run zizmor
         env:
-          ZIZMOR_CONFIG: ${{ steps.setup-config.outputs.zizmor-config }}
+          ZIZMOR_CONFIG_PATH: ${{ steps.setup-config.outputs.zizmor-config }}
           ZIZMOR_CACHE_DIR: ${{ runner.temp }}/.cache/zizmor
         shell: sh
         run: >-
@@ -385,7 +385,7 @@ jobs:
           --min-severity "${MIN_SEVERITY}"
           --min-confidence "${MIN_CONFIDENCE}"
           --cache-dir "${ZIZMOR_CACHE_DIR}"
-          ${ZIZMOR_CONFIG:+--config "${ZIZMOR_CONFIG}"}
+          ${ZIZMOR_CONFIG_PATH:+--config "${ZIZMOR_CONFIG_PATH}"}
           ${RUNNER_DEBUG:+"--verbose"}
           ${ZIZMOR_EXTRA_ARGS:+${ZIZMOR_EXTRA_ARGS}}
           .
@@ -410,7 +410,7 @@ jobs:
         id: zizmor-plain
         shell: bash
         env:
-          ZIZMOR_CONFIG: ${{ steps.setup-config.outputs.zizmor-config }}
+          ZIZMOR_CONFIG_PATH: ${{ steps.setup-config.outputs.zizmor-config }}
           ZIZMOR_CACHE_DIR: ${{ runner.temp }}/.cache/zizmor
         run: |
           set -o pipefail
@@ -425,7 +425,7 @@ jobs:
             --min-confidence "${MIN_CONFIDENCE}" \
             --cache-dir "${ZIZMOR_CACHE_DIR}" \
             ${RUNNER_DEBUG:+"--verbose"} \
-            ${ZIZMOR_CONFIG:+--config "${ZIZMOR_CONFIG}"} \
+            ${ZIZMOR_CONFIG_PATH:+--config "${ZIZMOR_CONFIG_PATH}"} \
             ${ZIZMOR_EXTRA_ARGS:+${ZIZMOR_EXTRA_ARGS}} \
             . \
             | tee -a "${GITHUB_OUTPUT}"
@@ -443,9 +443,9 @@ jobs:
 
       - name: Remove zizmor config
         env:
-          ZIZMOR_CONFIG: ${{ steps.setup-config.outputs.zizmor-config }}
+          ZIZMOR_CONFIG_PATH: ${{ steps.setup-config.outputs.zizmor-config }}
         if: steps.setup-config.outputs.zizmor-config
-        run: rm "${ZIZMOR_CONFIG}"
+        run: rm "${ZIZMOR_CONFIG_PATH}"
 
       - name: Hide any previous comments
         if: ${{ !cancelled() && github.event.pull_request.head.repo.full_name == github.repository }}

.github/workflows/test-get-vault-secrets.yaml

@@ -67,10 +67,12 @@ jobs:
       - name: Check secret value is ${{ matrix.instance }}
         if: matrix.instance != 'invalid'
         run: |
-          if [[ "${{ env.INSTANCE }}" != "${{ matrix.instance }}" ]]; then
+          if [[ "${INSTANCE}" != "${{ matrix.instance }}" ]]; then
             echo "Test failed: secret value does not match vault_instance input"
             exit 1
           fi
+        env:
+          INSTANCE: ${{ env.INSTANCE }}
 
       - name: Ensure 'invalid' errored
         if: matrix.instance == 'invalid' && steps.test-vault-action.outcome != 'failure'

.github/workflows/test-login-to-gar.yaml

@@ -20,15 +20,19 @@ on:
 
   merge_group:
 
-permissions:
-  contents: read
-  id-token: write
+permissions: {}
 
 jobs:
   test:
+    permissions:
+      contents: read
+      id-token: write
+
     runs-on: ubuntu-latest
+
     # Don't run for forks - they don't have access to secrets
     if: github.event.pull_request.head.repo.full_name == github.repository
+
     steps:
       - name: Harden the runner (Audit all outbound calls)
         uses: step-security/harden-runner@6c439dc8bdf85cadbbce9ed30d1c7b959517bc49 # v2.12.2

actions/build-push-to-dockerhub/README.md

@@ -3,10 +3,13 @@
 > [!NOTE]
 > If you are at Grafana Labs:
 >
-> - A docker mirror is available on our self-hosted runners, see [the internal documentation](https://enghub.grafana-ops.net/docs/default/component/deployment-tools/platform/continuous-integration/#docker-caching-in-github-actions) for more info.
+> - A docker mirror is available on our self-hosted runners, see [the internal
+>   documentation](https://enghub.grafana-ops.net/docs/default/component/deployment-tools/platform/continuous-integration/#docker-caching-in-github-actions)
+>   for more info.
 
-This is a composite GitHub Action, used to build Docker images and push them to DockerHub.
-It uses `get-vault-secrets` action to get the DockerHub username and password from Vault.
+This is a composite GitHub Action, used to build Docker images and push them to
+DockerHub. It uses `get-vault-secrets` action to get the DockerHub username and
+password from Vault.
 
 Example of how to use this action in a repository:
 
@@ -64,4 +67,8 @@ jobs:
 
 - If you specify `platforms` then the action will use buildx to build the image.
 - You must create a Dockerhub repo before you are able to push to it.
-- Most projects should be using Google Artifact Registry (instead of Dockerhub) to store their images. You can see more about that in the push-to-gar-docker shared workflow.
+- Most projects at Grafana Labs should be using Google Artifact Registry instead
+  of Dockerhub to store their images. You can see more about that in the
+  [push-to-gar-docker] shared workflow.
+
+[push-to-gar-docker]: ../push-to-gar-docker/README.md

actions/build-push-to-dockerhub/action.yaml

@@ -103,7 +103,16 @@ runs:
         images: ${{ inputs.repository }}
         tags: ${{ inputs.tags }}
 
-    - name: Build and push Docker image
+    # The `context` input is flagged by Zizmor as a [sink]. This means that with
+    # the upstream action the user's input to the input ends up in an output,
+    # and so if it's not handled properly, it could lead to a template injection
+    # attack. In this action, we pass through the inputs, but we don't then pass
+    # back the outputs, so we should be fine. Even if we did pass back the
+    # outputs, we consider ourselves a proxy, so in that case our job would be
+    # to warn users but not to take any action.
+    #
+    # [sink]: https://github.blog/security/application-security/how-to-secure-your-github-actions-workflows-with-codeql/#models
+    - name: Build and push Docker image # zizmor: ignore[template-injection]
       uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6.18.0
       with:
         context: ${{ inputs.context }}

actions/login-to-gcs/action.yaml

@@ -78,9 +78,11 @@ runs:
       if: ${{ inputs.delete_credentials_file == 'true' && env.GOOGLE_APPLICATION_CREDENTIALS != '' }}
       shell: sh
       run: |
-        if [ -f "${{ env.GOOGLE_APPLICATION_CREDENTIALS }}" ]; then
-          rm -f "${{ env.GOOGLE_APPLICATION_CREDENTIALS }}"
+        if [ -f "${GOOGLE_APPLICATION_CREDENTIALS}" ]; then
+          rm -f "${GOOGLE_APPLICATION_CREDENTIALS}"
           echo "::notice::Successfully deleted credentials file"
         else
-          echo "::warning::Credentials file not found at ${{ env.GOOGLE_APPLICATION_CREDENTIALS }}"
+          echo "::warning::Credentials file not found at ${GOOGLE_APPLICATION_CREDENTIALS}"
         fi
+      env:
+        GOOGLE_APPLICATION_CREDENTIALS: ${{ env.GOOGLE_APPLICATION_CREDENTIALS }}

actions/push-to-gar-docker/README.md

@@ -3,11 +3,16 @@
 > [!NOTE]
 > If you are at Grafana Labs:
 >
-> - Follow these steps in the [internal documentation](https://enghub.grafana-ops.net/docs/default/component/deployment-tools/platform/continuous-integration/google-artifact-registry/) to set up a repository before using this action.
-> - A docker mirror is available on our self-hosted runners, see [the internal documentation](https://enghub.grafana-ops.net/docs/default/component/deployment-tools/platform/continuous-integration/#docker-caching-in-github-actions) for more info.
+> - Follow these steps in the [internal
+>   documentation](https://enghub.grafana-ops.net/docs/default/component/deployment-tools/platform/continuous-integration/google-artifact-registry/)
+>   to set up a repository before using this action.
+> - A docker mirror is available on our self-hosted runners, see [the internal
+>   documentation](https://enghub.grafana-ops.net/docs/default/component/deployment-tools/platform/continuous-integration/#docker-caching-in-github-actions)
+>   for more info.
 
-This is a composite GitHub Action, used to push docker images to Google Artifact Registry (GAR).
-It uses [OIDC authentication](https://docs.github.com/en/actions/deployment/security-hardening-your-deployments/about-security-hardening-with-openid-connect)
+This is a composite GitHub Action, used to push docker images to Google Artifact
+Registry (GAR). It uses [OIDC
+authentication](https://docs.github.com/en/actions/deployment/security-hardening-your-deployments/about-security-hardening-with-openid-connect),
 which means that only workflows which get triggered based on certain rules can
 trigger these composite workflows.
 
@@ -80,6 +85,10 @@ input.
 
 ## Outputs
 
+> [!IMPORTANT]
+> Be careful when handling the `metadata` output. This contains user-supplied
+> information, and so it can be a vector for template injection.
+
 The following outputs are exposed from [`docker/metadata-action`](https://github.com/docker/metadata-action?tab=readme-ov-file#outputs) and [`docker/build-push-action`](https://github.com/docker/build-push-action?tab=readme-ov-file#outputs):
 
 | Name          | Type   | Description                    | From                       |

actions/push-to-gar-docker/action.yaml

@@ -173,7 +173,15 @@ runs:
         version: latest # see https://github.com/docker/build-push-action/issues/1345#issuecomment-2770572479
         buildkitd-config: ${{ runner.environment == 'self-hosted' && '/etc/buildkitd.toml' || '' }}
 
-    - name: Build the container
+    # The `context` input is flagged by Zizmor as a [sink]. This means that with
+    # the upstream action the user's input to the input ends up in an output,
+    # and so if it's not handled properly, it could lead to a template injection
+    # attack. In this action, we do pass this back out via our `metadata`
+    # output. However, we consider ourselves a proxy, so in that case our job is
+    # to warn users but not to take any action.
+    #
+    # [sink]: https://github.blog/security/application-security/how-to-secure-your-github-actions-workflows-with-codeql/#models
+    - name: Build the container # zizmor: ignore[template-injection]
       uses: docker/build-push-action@263435318d21b8e681c14492fe198d362a7d2c83 # v6.18.0
       id: build
       with:
@@ -207,9 +215,11 @@ runs:
       if: ${{ inputs.delete_credentials_file == 'true' && env.GOOGLE_APPLICATION_CREDENTIALS != '' }}
       shell: sh
       run: |
-        if [ -f "${{ env.GOOGLE_APPLICATION_CREDENTIALS }}" ]; then
-          rm -f "${{ env.GOOGLE_APPLICATION_CREDENTIALS }}"
+        if [ -f "${GOOGLE_APPLICATION_CREDENTIALS}" ]; then
+          rm -f "${GOOGLE_APPLICATION_CREDENTIALS}"
           echo "::notice::Successfully deleted credentials file"
         else
-          echo "::warning::Credentials file not found at ${{ env.GOOGLE_APPLICATION_CREDENTIALS }}"
+          echo "::warning::Credentials file not found at ${GOOGLE_APPLICATION_CREDENTIALS}"
         fi
+      env:
+        GOOGLE_APPLICATION_CREDENTIALS: ${{ env.GOOGLE_APPLICATION_CREDENTIALS }}

actions/push-to-gcs/action.yaml

@@ -120,9 +120,11 @@ runs:
       if: ${{ inputs.delete_credentials_file == 'true' && env.GOOGLE_APPLICATION_CREDENTIALS != '' }}
       shell: sh
       run: |
-        if [ -f "${{ env.GOOGLE_APPLICATION_CREDENTIALS }}" ]; then
-          rm -f "${{ env.GOOGLE_APPLICATION_CREDENTIALS }}"
+        if [ -f "${GOOGLE_APPLICATION_CREDENTIALS}" ]; then
+          rm -f "${GOOGLE_APPLICATION_CREDENTIALS}"
           echo "::notice::Successfully deleted credentials file"
         else
-          echo "::warning::Credentials file not found at ${{ env.GOOGLE_APPLICATION_CREDENTIALS }}"
+          echo "::warning::Credentials file not found at ${GOOGLE_APPLICATION_CREDENTIALS}"
         fi
+      env:
+        GOOGLE_APPLICATION_CREDENTIALS: ${{ env.GOOGLE_APPLICATION_CREDENTIALS }}