SQSCANGHA-140 Add OpenPGP signature verification for scanner downloads (#235)

src/main/gpg-verification.js

@@ -0,0 +1,240 @@
+/*
+ * sonarqube-scan-action
+ * Copyright (C) 2025 SonarSource SA
+ * mailto:info AT sonarsource DOT com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ */
+
+import * as core from "@actions/core";
+import * as exec from "@actions/exec";
+import * as fs from "node:fs";
+import * as os from "node:os";
+import * as path from "node:path";
+
+const SONARSOURCE_KEY_FINGERPRINT = "679F1EE92B19609DE816FDE81DB198F93525EC1A";
+const DEFAULT_KEYSERVER = "hkps://keyserver.ubuntu.com";
+const FALLBACK_KEYSERVER = "hkps://keys.openpgp.org";
+
+/**
+ * Verifies the GPG signature of a downloaded file
+ * @param {string} zipPath - Path to the downloaded ZIP file
+ * @param {string} signaturePath - Path to the .asc signature file
+ * @param {object} options - Verification options
+ * @param {string} options.keyFingerprint - GPG key fingerprint (default: SonarSource key)
+ * @param {string} options.keyserver - Primary keyserver URL (default: keyserver.ubuntu.com, with fallback to keys.openpgp.org)
+ * @returns {Promise<void>}
+ * @throws {Error} If GPG is unavailable or verification fails
+ */
+export async function verifySignature(zipPath, signaturePath, options = {}) {
+  const keyFingerprint = options.keyFingerprint || SONARSOURCE_KEY_FINGERPRINT;
+  const keyserver = options.keyserver || DEFAULT_KEYSERVER;
+
+  if (!(await isGpgAvailable())) {
+    throw new Error(
+      "GPG is not available. Install GPG or set skipSignatureVerification: true"
+    );
+  }
+
+  let gpgHome;
+  try {
+    gpgHome = setupGpgHome();
+    core.debug(`Created temporary GPG home: ${gpgHome}`);
+
+    await importSonarSourceKey(gpgHome, keyFingerprint, keyserver);
+    core.info("✓ SonarSource public key imported successfully");
+
+    await runGpgVerify(zipPath, signaturePath, gpgHome);
+    core.info("✓ GPG signature verification passed");
+  } finally {
+    if (gpgHome) {
+      cleanupGpgHome(gpgHome);
+    }
+  }
+}
+
+/**
+ * Checks if GPG is available on the system
+ * @returns {Promise<boolean>} True if GPG is available
+ */
+export async function isGpgAvailable() {
+  try {
+    const gpgCommand = getGpgCommand();
+    await exec.exec(gpgCommand, ["--version"], {
+      silent: true,
+      ignoreReturnCode: false,
+    });
+    return true;
+  } catch (error) {
+    core.debug(`GPG not available: ${error.message}`);
+    return false;
+  }
+}
+
+/**
+ * Gets the GPG command for the current platform
+ * @returns {string} GPG command name
+ */
+export function getGpgCommand() {
+  // GPG is available as 'gpg' on all GitHub-hosted runners
+  return "gpg";
+}
+
+/**
+ * Converts a Windows path to Unix-style path for GPG
+ * GPG on Windows (from Git for Windows) expects Unix-style paths
+ * @param {string} windowsPath - Windows path (e.g., C:\a\_temp\gpg-home)
+ * @returns {string} Unix-style path (e.g., /c/a/_temp/gpg-home)
+ */
+export function convertToUnixPath(windowsPath) {
+  if (process.platform !== "win32") {
+    return windowsPath;
+  }
+
+  let unixPath = windowsPath.replaceAll('\\', "/");
+
+  unixPath = unixPath.replace(/^([A-Za-z]):/, (match, drive) => {
+    return `/${drive.toLowerCase()}`;
+  });
+
+  return unixPath;
+}
+
+/**
+ * Creates a temporary GPG home directory
+ * @returns {string} Path to the temporary GPG home directory
+ */
+export function setupGpgHome() {
+  const tempDir = process.env.RUNNER_TEMP || os.tmpdir();
+  const gpgHome = path.join(tempDir, `gpg-home-${Date.now()}-${process.pid}`);
+
+  fs.mkdirSync(gpgHome, { recursive: true, mode: 0o700 });
+
+  return gpgHome;
+}
+
+/**
+ * Attempts to import a public key from a specific keyserver
+ * @param {string} gpgHome - Path to GPG home directory
+ * @param {string} keyFingerprint - Public key fingerprint
+ * @param {string} keyserver - Keyserver URL
+ * @returns {Promise<void>}
+ * @throws {Error} If key import fails
+ */
+async function tryImportKey(gpgHome, keyFingerprint, keyserver) {
+  const gpgCommand = getGpgCommand();
+  const gpgHomePath = convertToUnixPath(gpgHome);
+
+  await exec.exec(
+    gpgCommand,
+    [
+      "--homedir",
+      gpgHomePath,
+      "--batch",
+      "--keyserver",
+      keyserver,
+      "--recv-keys",
+      keyFingerprint,
+    ],
+    {
+      silent: false,
+    }
+  );
+}
+
+/**
+ * Imports the SonarSource public key from a keyserver
+ * @param {string} gpgHome - Path to GPG home directory
+ * @param {string} keyFingerprint - Public key fingerprint
+ * @param {string} keyserver - Keyserver URL
+ * @returns {Promise<void>}
+ * @throws {Error} If key import fails
+ */
+export async function importSonarSourceKey(gpgHome, keyFingerprint, keyserver) {
+  let primaryError;
+
+  try {
+    core.info(`Importing SonarSource public key from ${keyserver}...`);
+    await tryImportKey(gpgHome, keyFingerprint, keyserver);
+    core.info(`Successfully imported key from ${keyserver}`);
+    return;
+  } catch (error) {
+    primaryError = error;
+    core.warning(
+      `Failed to import key from ${keyserver}: ${error.message}`
+    );
+  }
+
+  try {
+    core.info(`Attempting fallback keyserver ${FALLBACK_KEYSERVER}...`);
+    await tryImportKey(gpgHome, keyFingerprint, FALLBACK_KEYSERVER);
+    core.info(`Successfully imported key from fallback keyserver ${FALLBACK_KEYSERVER}`);
+  } catch (fallbackError) {
+    throw new Error(
+      `Failed to import SonarSource public key from all keyservers. ` +
+      `Primary (${keyserver}): ${primaryError.message}. ` +
+      `Fallback (${FALLBACK_KEYSERVER}): ${fallbackError.message}`
+    );
+  }
+}
+
+/**
+ * Runs GPG verification on the downloaded file
+ * @param {string} zipPath - Path to the ZIP file
+ * @param {string} signaturePath - Path to the signature file
+ * @param {string} gpgHome - Path to GPG home directory
+ * @returns {Promise<void>}
+ * @throws {Error} If verification fails
+ */
+export async function runGpgVerify(zipPath, signaturePath, gpgHome) {
+  const gpgCommand = getGpgCommand();
+
+  try {
+    core.info("Verifying GPG signature...");
+    await exec.exec(
+      gpgCommand,
+      [
+        "--homedir",
+        convertToUnixPath(gpgHome),
+        "--batch",
+        "--verify",
+        convertToUnixPath(signaturePath),
+        convertToUnixPath(zipPath),
+      ],
+      {
+        silent: false,
+      }
+    );
+  } catch (error) {
+    throw new Error(
+      `GPG signature verification failed - file may be corrupted or tampered: ${error.message}`
+    );
+  }
+}
+
+/**
+ * Cleans up the temporary GPG home directory
+ * @param {string} gpgHome - Path to GPG home directory
+ */
+export function cleanupGpgHome(gpgHome) {
+  try {
+    if (fs.existsSync(gpgHome)) {
+      fs.rmSync(gpgHome, { recursive: true, force: true });
+      core.debug(`Cleaned up temporary GPG home: ${gpgHome}`);
+    }
+  } catch (error) {
+    core.warning(`Failed to cleanup temporary GPG home: ${error.message}`);
+  }
+}