feat: harden setup-db action

setup-db/action.yaml

@@ -10,6 +10,10 @@ inputs:
     description: "Path to the Trivy cache directory (default: ${{runner.temp}}/trivy)"
     required: false
     default: "${{ runner.temp }}/trivy"
+  trivy-version:
+    description: "Trivy docker image version to use (full image reference including digest is recommended)"
+    required: false
+    default: "ghcr.io/aquasecurity/trivy:0.69.3@sha256:bcc376de8d77cfe086a917230e818dc9f8528e3c852f7b1aff648949b6258d1c"
 
 outputs:
   cache-dir:
@@ -32,4 +36,21 @@ runs:
           trivy-db-${{ steps.current-date.outputs.current-date }}
     - if: steps.restore-db.outputs.cache-hit != 'true'
       shell: bash
-      run: trivy fs --download-db-only --cache-dir "${{ inputs.cache-dir }}"
+      run: |
+        docker run --rm \
+          --name trivy-db-download \
+          --user "$(id -u):$(id -g)" \
+          --read-only \
+          --env-file /dev/null \
+          --cap-drop ALL \
+          --pids-limit 64 \
+          --memory=512m \
+          --memory-swap=512m \
+          --cpus=1 \
+          --ipc private \
+          --cgroupns private \
+          --security-opt no-new-privileges \
+          --security-opt apparmor=docker-default \
+          --tmpfs /tmp:rw,noexec,nosuid,nodev,size=1g \
+          --mount type=bind,src=${{ inputs.cache-dir }},dst=/cache \
+          ${{ inputs.trivy-version }} fs --download-db-only --cache-dir /cache