SonarQube Scan (Fork PR) #67
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| name: SonarQube Scan (Fork PR) | |
| # ---------------------------------------------------------------------------- | |
| # SECURITY MODEL — read before editing. | |
| # | |
| # This workflow analyses fork pull requests with SonarCloud while holding the | |
| # SONAR_TOKEN. The previous design (pull_request_target + checkout of PR HEAD | |
| # + projectBaseDir pointing at fork-controlled content) was a textbook | |
| # pwn-request: a fork PR could ship its own sonar-project.properties under the | |
| # detected base dir and redirect the scanner's sonar.host.url, exfiltrating | |
| # SONAR_TOKEN to an attacker host. CVE-class. Do not reintroduce that pattern. | |
| # | |
| # This workflow is safe because: | |
| # | |
| # 1. workflow_run executes against the workflow definition on the DEFAULT | |
| # branch, never the PR HEAD. A fork cannot replace this file. | |
| # 2. The repository is checked out at the BASE commit (master), so the | |
| # trusted root sonar-project.properties is what the scanner reads. | |
| # 3. The fork's coverage report and source archive are downloaded as | |
| # ARTIFACTS — treated as untrusted DATA. We never execute anything from | |
| # them (no pip/npm install, no shell). The source is only fed to the | |
| # scanner as files to analyse. | |
| # 4. sonar.host.url / sonar.organization / sonar.projectKey are forced on | |
| # the scanner CLI. CLI arguments take precedence over any properties | |
| # file, so even if the fork smuggled one through it cannot redirect the | |
| # scanner's authentication target. | |
| # 5. PR metadata fields that flow into the scanner CLI (head_ref, base_ref, | |
| # pr_number) are validated against strict regexes before use. Untrusted | |
| # strings never expand directly inside a `run:` block. | |
| # | |
| # If you need to relax any of these constraints, get a security review first. | |
| # ---------------------------------------------------------------------------- | |
| on: | |
| workflow_run: | |
| workflows: ["Code Quality"] | |
| types: [completed] | |
| permissions: | |
| contents: read | |
| jobs: | |
| sonar_fork_pr: | |
| runs-on: ubuntu-latest | |
| if: >- | |
| ${{ github.event.workflow_run.event == 'pull_request' | |
| && github.event.workflow_run.conclusion == 'success' | |
| && github.event.workflow_run.head_repository.fork == true }} | |
| permissions: | |
| contents: read | |
| pull-requests: write | |
| steps: | |
| - name: Checkout trusted base (master) | |
| uses: actions/checkout@b4ffde65f46336ab88eb53be808477a3936bae11 # v4 | |
| with: | |
| ref: master | |
| fetch-depth: 0 | |
| - name: Download fork PR artifact | |
| uses: actions/download-artifact@d3f86a106a0bac45b974a628896c90dbdf5c8093 # v4 | |
| with: | |
| name: sonar-fork-pr | |
| path: fork-artifact | |
| github-token: ${{ secrets.GITHUB_TOKEN }} | |
| run-id: ${{ github.event.workflow_run.id }} | |
| - name: Validate fork PR metadata | |
| id: meta | |
| env: | |
| # workflow_run-provided values are trusted (they come from GitHub, | |
| # not the fork). Use these for cross-checks. | |
| WR_PR_NUMBER: ${{ github.event.workflow_run.pull_requests[0].number }} | |
| WR_HEAD_SHA: ${{ github.event.workflow_run.head_sha }} | |
| run: | | |
| set -euo pipefail | |
| if [ ! -f fork-artifact/pr-meta.json ]; then | |
| echo "::error::pr-meta.json missing from fork artifact" | |
| exit 1 | |
| fi | |
| # Parse with jq, then validate each field with a strict regex | |
| # BEFORE writing to GITHUB_OUTPUT. Anything failing validation is | |
| # fatal — better to skip the analysis than to feed an attacker | |
| # string into the scanner CLI. | |
| pr_number=$(jq -r '.pr_number // empty' fork-artifact/pr-meta.json) | |
| head_sha=$( jq -r '.head_sha // empty' fork-artifact/pr-meta.json) | |
| head_ref=$( jq -r '.head_ref // empty' fork-artifact/pr-meta.json) | |
| base_sha=$( jq -r '.base_sha // empty' fork-artifact/pr-meta.json) | |
| base_ref=$( jq -r '.base_ref // empty' fork-artifact/pr-meta.json) | |
| # PR number must match the one GitHub itself reports for this run. | |
| if [ -z "$pr_number" ] || [ "$pr_number" != "$WR_PR_NUMBER" ]; then | |
| echo "::error::pr_number from artifact ($pr_number) does not match workflow_run PR ($WR_PR_NUMBER)" | |
| exit 1 | |
| fi | |
| # Head SHA must match the one GitHub reports. | |
| if [ -z "$head_sha" ] || [ "$head_sha" != "$WR_HEAD_SHA" ]; then | |
| echo "::error::head_sha from artifact ($head_sha) does not match workflow_run head ($WR_HEAD_SHA)" | |
| exit 1 | |
| fi | |
| # Branch names: git allows a lot, but Sonar only needs something | |
| # that round-trips through a CLI arg. Keep it conservative. | |
| ref_re='^[A-Za-z0-9._/-]{1,250}$' | |
| if ! [[ "$head_ref" =~ $ref_re ]]; then | |
| echo "::error::head_ref failed validation: $head_ref" | |
| exit 1 | |
| fi | |
| if ! [[ "$base_ref" =~ $ref_re ]]; then | |
| echo "::error::base_ref failed validation: $base_ref" | |
| exit 1 | |
| fi | |
| sha_re='^[0-9a-f]{40}$' | |
| if ! [[ "$base_sha" =~ $sha_re ]]; then | |
| echo "::error::base_sha failed validation: $base_sha" | |
| exit 1 | |
| fi | |
| { | |
| echo "pr_number=$pr_number" | |
| echo "head_ref=$head_ref" | |
| echo "base_ref=$base_ref" | |
| } >> "$GITHUB_OUTPUT" | |
| - name: Stage PR sources for analysis | |
| run: | | |
| set -euo pipefail | |
| mkdir -p pr-src | |
| if [ -f fork-artifact/pr-source.tar.gz ]; then | |
| tar -xzf fork-artifact/pr-source.tar.gz -C pr-src | |
| else | |
| echo "::warning::pr-source.tar.gz missing; scanner will run with no source overlay" | |
| fi | |
| if [ -f fork-artifact/coverage.xml ]; then | |
| cp fork-artifact/coverage.xml ./coverage.xml | |
| else | |
| echo "::warning::coverage.xml missing; running scanner without coverage data" | |
| fi | |
| - name: SonarQube Scan (fork PR, trusted base) | |
| uses: SonarSource/sonarqube-scan-action@713881670b6b3676cda39549040e2d88c70d582e # v8.2.0 | |
| env: | |
| SONAR_TOKEN: ${{ secrets.SONAR_TOKEN }} | |
| GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }} | |
| with: | |
| # Run from the TRUSTED base checkout so the trusted root | |
| # sonar-project.properties is what gets loaded. The fork's source | |
| # tree is fed in below via -Dsonar.sources only. | |
| projectBaseDir: . | |
| args: >- | |
| -Dsonar.host.url=https://sonarcloud.io | |
| -Dsonar.organization=mitre | |
| -Dsonar.projectKey=mitre_caldera | |
| -Dsonar.sources=pr-src/app | |
| -Dsonar.python.coverage.reportPaths=coverage.xml | |
| -Dsonar.pullrequest.key=${{ steps.meta.outputs.pr_number }} | |
| -Dsonar.pullrequest.branch=${{ steps.meta.outputs.head_ref }} | |
| -Dsonar.pullrequest.base=${{ steps.meta.outputs.base_ref }} |