3 files changed, 100 insertions, 3 deletions
diff --git a/toolkit/modules/GMPInstallManager.sys.mjs b/toolkit/modules/GMPInstallManager.sys.mjs
index 9cb4802e58..421a843c71 100644
--- a/toolkit/modules/GMPInstallManager.sys.mjs
+++ b/toolkit/modules/GMPInstallManager.sys.mjs
@@ -43,6 +43,16 @@ const LOCAL_GMP_SOURCES = [
   },
 ];
 
+function getLocalSources() {
+  if (GMPPrefs.getBool(GMPPrefs.KEY_ALLOW_LOCAL_SOURCES, true)) {
+    return LOCAL_GMP_SOURCES;
+  }
+
+  let log = getScopedLogger("GMPInstallManager.downloadLocalConfig");
+  log.info("ignoring local sources");
+  return [];
+}
+
 function downloadJSON(uri) {
   let log = getScopedLogger("GMPInstallManager.checkForAddons");
   log.info("fetching config from: " + uri);
@@ -70,7 +80,7 @@ function downloadJSON(uri) {
 function downloadLocalConfig() {
   let log = getScopedLogger("GMPInstallManager.downloadLocalConfig");
   return Promise.all(
-    LOCAL_GMP_SOURCES.map(conf => {
+    getLocalSources().map(conf => {
       return downloadJSON(conf.src).then(addons => {
         let platforms = addons.vendors[conf.id].platforms;
         let target = Services.appinfo.OS + "_" + lazy.UpdateUtils.ABI;
@@ -146,6 +156,36 @@ GMPInstallManager.prototype = {
   },
 
   /**
+   * Determines the root to use for verifying content signatures.
+   * @param url
+   *        The Balrog URL, i.e. the return value of _getURL().
+   */
+  _getContentSignatureRootForURL(url) {
+    // The prod and stage URLs of Balrog are documented at:
+    // https://mozilla-balrog.readthedocs.io/en/latest/infrastructure.html
+    // Note: we are matching by prefix without the full domain nor slash, to
+    // enable us to move to a different host name in the future if desired.
+    if (url.startsWith("https://aus")) {
+      return Ci.nsIContentSignatureVerifier.ContentSignatureProdRoot;
+    }
+    if (url.startsWith("https://stage.")) {
+      return Ci.nsIContentSignatureVerifier.ContentSignatureStageRoot;
+    }
+    if (Services.env.exists("XPCSHELL_TEST_PROFILE_DIR")) {
+      return Ci.nsIX509CertDB.AppXPCShellRoot;
+    }
+    // When content signature verification for GMP was added (bug 1714621), a
+    // pref existed to configure an arbitrary root, which enabled local testing.
+    // This pref was removed later in bug 1769669, and replaced with hard-coded
+    // roots (prod and tests only). Support for testing against the stage server
+    // was restored in bug 1771992.
+    // Note: other verifiers ultimately fall back to ContentSignatureLocalRoot,
+    // to support local development. Here we use ContentSignatureProdRoot to
+    // minimize risk (and the unclear demand for "local" development).
+    return Ci.nsIContentSignatureVerifier.ContentSignatureProdRoot;
+  },
+
+  /**
    * Records telemetry results on if fetching update.xml from Balrog succeeded
    * when content signature was used to verify the response from Balrog.
    * @param didGetAddonList
@@ -318,15 +358,17 @@ GMPInstallManager.prototype = {
     }
 
     let url = await this._getURL();
+    let trustedContentSignatureRoot = this._getContentSignatureRootForURL(url);
 
     log.info(
-      `Fetching product addon list url=${url}, allowNonBuiltIn=${allowNonBuiltIn}, certs=${certs}, checkContentSignature=${checkContentSignature}`
+      `Fetching product addon list url=${url}, allowNonBuiltIn=${allowNonBuiltIn}, certs=${certs}, checkContentSignature=${checkContentSignature}, trustedContentSignatureRoot=${trustedContentSignatureRoot}`
     );
     let addonPromise = ProductAddonChecker.getProductAddonList(
       url,
       allowNonBuiltIn,
       certs,
-      checkContentSignature
+      checkContentSignature,
+      trustedContentSignatureRoot
     )
       .then(res => {
         if (checkContentSignature) {
diff --git a/toolkit/modules/GMPUtils.sys.mjs b/toolkit/modules/GMPUtils.sys.mjs
index 488a024d13..c21576e0a9 100644
--- a/toolkit/modules/GMPUtils.sys.mjs
+++ b/toolkit/modules/GMPUtils.sys.mjs
@@ -124,6 +124,7 @@ export var GMPPrefs = {
   KEY_PLUGIN_ABI: "media.{0}.abi",
   KEY_PLUGIN_FORCE_SUPPORTED: "media.{0}.forceSupported",
   KEY_PLUGIN_ALLOW_X64_ON_ARM64: "media.{0}.allow-x64-plugin-on-arm64",
+  KEY_ALLOW_LOCAL_SOURCES: "media.gmp-manager.allowLocalSources",
   KEY_URL: "media.gmp-manager.url",
   KEY_URL_OVERRIDE: "media.gmp-manager.url.override",
   KEY_CERT_CHECKATTRS: "media.gmp-manager.cert.checkAttributes",
diff --git a/toolkit/modules/tests/xpcshell/test_GMPInstallManager.js b/toolkit/modules/tests/xpcshell/test_GMPInstallManager.js
index 87de57efaf..e755690e6c 100644
--- a/toolkit/modules/tests/xpcshell/test_GMPInstallManager.js
+++ b/toolkit/modules/tests/xpcshell/test_GMPInstallManager.js
@@ -802,6 +802,60 @@ add_task(async function test_checkForAddons_contentSignatureFailure() {
 });
 
 /**
+ * Tests that the signature verification URL is as expected.
+ */
+add_task(async function test_checkForAddons_get_verifier_url() {
+  const previousUrlOverride = setupContentSigTestPrefs();
+
+  let installManager = new GMPInstallManager();
+  // checkForAddons() calls _getContentSignatureRootForURL() with the return
+  // value of _getURL(), which is effectively KEY_URL_OVERRIDE or KEY_URL
+  // followed by some normalization.
+  const rootForUrl = async () => {
+    const url = await installManager._getURL();
+    return installManager._getContentSignatureRootForURL(url);
+  };
+
+  Assert.equal(
+    await rootForUrl(),
+    Ci.nsIX509CertDB.AppXPCShellRoot,
+    "XPCShell root used by default in xpcshell test"
+  );
+
+  const defaultPrefs = Services.prefs.getDefaultBranch("");
+  const defaultUrl = defaultPrefs.getStringPref(GMPPrefs.KEY_URL);
+  Preferences.set(GMPPrefs.KEY_URL_OVERRIDE, defaultUrl);
+  Assert.equal(
+    await rootForUrl(),
+    Ci.nsIContentSignatureVerifier.ContentSignatureProdRoot,
+    "Production cert should be used for the default Balrog URL: " + defaultUrl
+  );
+
+  // The current Balrog endpoint is at aus5.mozilla.org. Confirm that the prod
+  // cert is used even if we bump the version (e.g. aus6):
+  const potentialProdUrl = "https://aus1337.mozilla.org/potential/prod/URL";
+  Preferences.set(GMPPrefs.KEY_URL_OVERRIDE, potentialProdUrl);
+  Assert.equal(
+    await rootForUrl(),
+    Ci.nsIContentSignatureVerifier.ContentSignatureProdRoot,
+    "Production cert should be used for: " + potentialProdUrl
+  );
+
+  // Stage URL documented at https://mozilla-balrog.readthedocs.io/en/latest/infrastructure.html
+  const stageUrl = "https://stage.balrog.nonprod.cloudops.mozgcp.net/etc.";
+  Preferences.set(GMPPrefs.KEY_URL_OVERRIDE, stageUrl);
+  Assert.equal(
+    await rootForUrl(),
+    Ci.nsIContentSignatureVerifier.ContentSignatureStageRoot,
+    "Stage cert should be used with the stage URL: " + stageUrl
+  );
+
+  installManager.uninit();
+
+  revertContentSigTestPrefs(previousUrlOverride);
+});
+
+/**
  * Tests that checkForAddons() works as expected when certificate pinning
  * checking is enabled. We plan to move away from cert pinning in favor of
  * content signature checks, but part of doing this is comparing the telemetry