feat(ci): update Trivy setup script with upstream verification and cosign integration

Author: Sudo-Ivan

scripts/ci/setup-trivy.sh

@@ -1,7 +1,74 @@
 #!/bin/sh
-# Install Trivy .deb for CI (same package as scan / docker workflows).
+# Install Trivy .deb for CI (scan / docker workflows). Upstream path: Sigstore on
+# trivy_${VER}_checksums.txt, SHA256 of the .deb against that file, then Sigstore on the .deb.
+# Custom mirror: TRIVY_DEB_URL and TRIVY_DEB_SHA256 (sha256sum -c format, hex only).
 set -eu
 
-curl -fsSL -o /tmp/trivy.deb https://git.quad4.io/Quad4-Software/Trivy-Assets/raw/commit/fdfe96b77d2f7b7f5a90cea00af5024c9f728f17/trivy_0.69.3_Linux-64bit.deb
+COSIGN_VERSION="${COSIGN_VERSION:-3.0.6}"
+TRIVY_VERSION="${TRIVY_VERSION:-0.69.3}"
+TRIVY_RELEASE_BASE="https://github.com/aquasecurity/trivy/releases/download/v${TRIVY_VERSION}"
+# Keyless signing identity for aquasecurity/trivy reusable release workflow (any semver tag).
+TRIVY_CERT_IDENTITY_RE='^https://github.com/aquasecurity/trivy/\.github/workflows/reusable-release\.yaml@refs/tags/v[0-9]+\.[0-9]+\.[0-9]+$'
+TRIVY_CERT_ISSUER_RE='^https://token\.actions\.githubusercontent\.com$'
+
+ensure_cosign() {
+    if command -v cosign >/dev/null 2>&1; then
+        return 0
+    fi
+    sh scripts/ci/setup-cosign.sh "${COSIGN_VERSION}"
+}
+
+verify_upstream_deb() {
+    deb_arch="$1"
+    DEB_BASE="trivy_${TRIVY_VERSION}_${deb_arch}.deb"
+
+    ensure_cosign
+    export COSIGN_YES="${COSIGN_YES:-true}"
+
+    curl -fsSL -o /tmp/trivy_checksums.txt "${TRIVY_RELEASE_BASE}/trivy_${TRIVY_VERSION}_checksums.txt"
+    curl -fsSL -o /tmp/trivy_checksums.sigstore.json "${TRIVY_RELEASE_BASE}/trivy_${TRIVY_VERSION}_checksums.txt.sigstore.json"
+    cosign verify-blob /tmp/trivy_checksums.txt --bundle /tmp/trivy_checksums.sigstore.json \
+        --certificate-identity-regexp="${TRIVY_CERT_IDENTITY_RE}" \
+        --certificate-oidc-issuer-regexp="${TRIVY_CERT_ISSUER_RE}"
+
+    EXPECTED_SHA="$(awk -v f="${DEB_BASE}" '$2 == f { print $1; exit }' /tmp/trivy_checksums.txt)"
+    if [ -z "${EXPECTED_SHA}" ]; then
+        echo "setup-trivy.sh: no SHA256 line for ${DEB_BASE} in checksums.txt" >&2
+        exit 1
+    fi
+
+    curl -fsSL -o /tmp/trivy.deb "${TRIVY_RELEASE_BASE}/${DEB_BASE}"
+    echo "${EXPECTED_SHA}  /tmp/trivy.deb" | sha256sum -c
+
+    curl -fsSL -o /tmp/trivy.deb.sigstore.json "${TRIVY_RELEASE_BASE}/${DEB_BASE}.sigstore.json"
+    cosign verify-blob /tmp/trivy.deb --bundle /tmp/trivy.deb.sigstore.json \
+        --certificate-identity-regexp="${TRIVY_CERT_IDENTITY_RE}" \
+        --certificate-oidc-issuer-regexp="${TRIVY_CERT_ISSUER_RE}"
+
+    rm -f /tmp/trivy_checksums.txt /tmp/trivy_checksums.sigstore.json /tmp/trivy.deb.sigstore.json
+}
+
+if [ -n "${TRIVY_DEB_URL:-}" ]; then
+    if [ -z "${TRIVY_DEB_SHA256:-}" ]; then
+        echo "setup-trivy.sh: TRIVY_DEB_URL requires TRIVY_DEB_SHA256" >&2
+        exit 1
+    fi
+    curl -fsSL -o /tmp/trivy.deb "${TRIVY_DEB_URL}"
+    echo "${TRIVY_DEB_SHA256}  /tmp/trivy.deb" | sha256sum -c
+else
+    arch="$(uname -m)"
+    deb_arch=
+    case "$arch" in
+        x86_64|amd64) deb_arch=Linux-64bit ;;
+        aarch64|arm64) deb_arch=Linux-ARM64 ;;
+        armv7l|armv6l|armhf) deb_arch=Linux-ARM ;;
+        *)
+            echo "setup-trivy.sh: unsupported uname -m: ${arch} (set TRIVY_DEB_URL)" >&2
+            exit 1
+            ;;
+    esac
+    verify_upstream_deb "${deb_arch}"
+fi
+
 sh scripts/ci/exec-priv.sh dpkg -i /tmp/trivy.deb || sh scripts/ci/exec-priv.sh apt-get install -f -y
 trivy --version