training/articles/security-gms-provider.jd

page.title=Updating Your Security Provider to Protect Against SSL Exploits
page.tags="network","certificates"

page.article=true
@jd:body

<div id="tb-wrapper">
<div id="tb">
<h2>In this document</h2>
<ol class="nolist">
  <li><a href="#patching">Patching the Security Provider with
      ProviderInstaller</a></li>
  <li><a href="#example_sync">Patching Synchronously</a></li>
  <li><a href="#example_async">Patching Asynchronously</a></li>

</ol>


<h2>See also</h2>
<ul>
  <li><a href="{@docRoot}google/play-services/">Google Play Services</a></li>
  <li><a href="https://www.openssl.org/news/secadv_20140605.txt">OpenSSL
   Security Advisory [05 Jun 2014]: SSL/TLS MITM vulnerability
   (CVE-2014-0224)</a></li>
  <li><a href="http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-0224">
    Vulnerability Summary for CVE-2014-0224</a></li>
</ul>
</div>
</div>


<p> Android relies on a security {@link java.security.Provider Provider} to
provide secure network communications. However, from time to time,
vulnerabilities are found in the default security provider. To protect against
these vulnerabilities, <a href="{@docRoot}google/play-services/">Google Play
services</a> provides a way to automatically update a device's security provider
to protect against known exploits. By calling Google Play services methods, your
app can ensure that it's running on a device that has the latest updates to
protect against known exploits.</p>

<p>For example, a vulnerability was discovered in OpenSSL
(<a href="http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-0224">CVE-2014-0224</a>)
that can leave apps open to a "man-in-the-middle" attack that decrypts
secure traffic without either side knowing. With Google Play services version
5.0, a fix is available, but apps must ensure that this fix is installed. By
using the Google Play services methods, your app can ensure that it's running
on a device that's secured against that attack.</p>

<p class="caution"><strong>Caution: </strong>Updating a device's security {@link
java.security.Provider Provider} does <em>not</em> update {@link
android.net.SSLCertificateSocketFactory
android.net.SSLCertificateSocketFactory}. Rather than using this class, we
encourage app developers to use high-level methods for interacting with
cryptography. Most apps can use APIs like {@link
javax.net.ssl.HttpsURLConnection} without needing to set a custom
{@link javax.net.ssl.TrustManager} or create an {@link
android.net.SSLCertificateSocketFactory}.</p>

<h2 id="patching">Patching the Security Provider with ProviderInstaller</h2>

<p>To update a device's security provider, use the
<a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html">{@code ProviderInstaller}</a>
class. You can verify that the security provider is up-to-date (and update it,
if necessary) by calling
that class's <a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html##installIfNeeded(android.content.Context)">{@code installIfNeeded()}</a>
(or <a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html#installIfNeededAsync(android.content.Context, com.google.android.gms.security.ProviderInstaller.ProviderInstallListener)">{@code installIfNeededAsync()}</a>)
method.</p>

<p>When you call <a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html##installIfNeeded(android.content.Context)">{@code installIfNeeded()}</a>, the
<a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html">{@code ProviderInstaller}</a>
does the following:</p>

<ul>
  <li>If the device's {@link java.security.Provider Provider} is successfully
    updated (or is already up-to-date), the method returns normally.</li>
  <li>If the device's Google Play services library is out of date, the method
    throws
    <a href="{@docRoot}reference/com/google/android/gms/common/GooglePlayServicesRepairableException.html">{@code GooglePlayServicesRepairableException}</a>.
    The app can then catch this exception and show
    the user an appropriate dialog box to update Google Play services.</li>
    <li>If a non-recoverable error occurs, the method throws
    <a href="{@docRoot}reference/com/google/android/gms/common/GooglePlayServicesNotAvailableException.html">{@code GooglePlayServicesNotAvailableException}</a>
    to indicate that it is unable to update the {@link java.security.Provider
    Provider}. The app can then catch the exception and choose an appropriate
    course of action, such as displaying the standard
    <a href="{@docRoot}reference/com/google/android/gms/common/SupportErrorDialogFragment.html">fix-it flow diagram</a>.</li>
</ul>

<p>The
<a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html#installIfNeededAsync(android.content.Context, com.google.android.gms.security.ProviderInstaller.ProviderInstallListener)">{@code installIfNeededAsync()}</a>
method behaves similarly, except that instead of
throwing exceptions, it calls the appropriate callback method to indicate
success or failure.</p>

<p>If <a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html##installIfNeeded(android.content.Context)">{@code installIfNeeded()}</a>
needs to install a new {@link java.security.Provider Provider}, this can take
anywhere from 30-50 milliseconds (on more recent devices) to 350 ms (on older
devices). If the security provider is already up-to-date, the method takes a
negligible amount of time. To avoid affecting user experience:</p>

<ul>
  <li>Call
  <a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html##installIfNeeded(android.content.Context)">{@code installIfNeeded()}</a>
  from background networking threads immediately when the threads are loaded,
  instead of waiting for the thread to try to use the network. (There's no harm
  in calling the method multiple times, since it returns immediately if the
  security provider doesn't need updating.)</li>

  <li>If user experience will be affected by the thread blocking--for example,
  if the call is from an activity in the UI thread--call the asynchronous
  version of the method,
  <a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html#installIfNeededAsync(android.content.Context, com.google.android.gms.security.ProviderInstaller.ProviderInstallListener)">{@code installIfNeededAsync()}</a>.
  (Of course, if you do this, you need to wait for the operation to finish
  before you attempt any secure communications. The
  <a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html">{@code ProviderInstaller}</a>
  calls your listener's <a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.ProviderInstallListener.html#onProviderInstalled()">{@code onProviderInstalled()}</a>
  method to signal success.)</li>
</ul>

<p class="warning"><strong>Warning:</strong> If the
<a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html">{@code ProviderInstaller}</a>
is unable to install an updated {@link java.security.Provider Provider},
your device's security provider might be vulnerable  to known exploits. Your app
should behave as if all HTTP communication is unencrypted.</p>

<p>Once the {@link java.security.Provider Provider} is updated, all calls to
security APIs (including SSL APIs) are routed through it.
(However, this does not apply to  {@link android.net.SSLCertificateSocketFactory
android.net.SSLCertificateSocketFactory}, which remains vulnerable to such
exploits as
<a href="http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2014-0224">CVE-2014-0224</a>.)</p>

<h2 id="example_sync">Patching Synchronously</h2>

<p>The simplest way to patch the security provider is to call the synchronous
method <a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html##installIfNeeded(android.content.Context)">{@code installIfNeeded()}</a>.
This is appropriate if user experience won't be affected by the thread blocking
while it waits for the operation to finish.</p>

<p>For example, here's an implementation of a <a href="{@docRoot}training/sync-adapters">sync adapter</a> that updates the security provider. Since a sync
adapter runs in the background, it's okay if the thread blocks while waiting
for the security provider to be updated. The sync adapter calls
<a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html##installIfNeeded(android.content.Context)">{@code installIfNeeded()}</a> to
update the security provider. If the method returns normally, the sync adapter
knows the security provider is up-to-date. If the method throws an exception,
the sync adapter can take appropriate action (such as prompting the user to
update Google Play services).</p>

<pre>/**
 * Sample sync adapter using {&#64;link ProviderInstaller}.
 */
public class SyncAdapter extends AbstractThreadedSyncAdapter {

  ...

  // This is called each time a sync is attempted; this is okay, since the
  // overhead is negligible if the security provider is up-to-date.
  &#64;Override
  public void onPerformSync(Account account, Bundle extras, String authority,
      ContentProviderClient provider, SyncResult syncResult) {
    try {
      ProviderInstaller.installIfNeeded(getContext());
    } catch (GooglePlayServicesRepairableException e) {

      // Indicates that Google Play services is out of date, disabled, etc.

      // Prompt the user to install/update/enable Google Play services.
      GooglePlayServicesUtil.showErrorNotification(
          e.getConnectionStatusCode(), getContext());

      // Notify the SyncManager that a soft error occurred.
      syncResult.stats.numIOExceptions++;
      return;

    } catch (GooglePlayServicesNotAvailableException e) {
      // Indicates a non-recoverable error; the ProviderInstaller is not able
      // to install an up-to-date Provider.

      // Notify the SyncManager that a hard error occurred.
      syncResult.stats.numAuthExceptions++;
      return;
    }

    // If this is reached, you know that the provider was already up-to-date,
    // or was successfully updated.
  }
}</pre>

<h2 id="example_async">Patching Asynchronously</h2>

<p>Updating the security provider can take as much as 350 milliseconds (on
older devices). If you're doing the update on a thread that directly affects
user experience, such as the UI thread, you don't want to make a synchronous
call to update the provider, since that can result in the app or device
freezing until the operation finishes. Instead, you should use the asynchronous
method
<a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html#installIfNeededAsync(android.content.Context, com.google.android.gms.security.ProviderInstaller.ProviderInstallListener)">{@code installIfNeededAsync()}</a>.
That method indicates its success or failure by calling callbacks.</p>

<p>For example, here's some code that updates the security provider in an
activity in the UI thread. The activity calls <a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.html#installIfNeededAsync(android.content.Context, com.google.android.gms.security.ProviderInstaller.ProviderInstallListener)">{@code installIfNeededAsync()}</a>
to update the provider, and designates itself as the listener to receive success
or failure notifications. If the security provider is up-to-date or is
successfully updated, the activity's
<a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.ProviderInstallListener.html#onProviderInstalled()">{@code onProviderInstalled()}</a>
method is called, and the activity knows communication is secure. If the
provider cannot be updated, the activity's
<a href="{@docRoot}reference/com/google/android/gms/security/ProviderInstaller.ProviderInstallListener.html#onProviderInstallFailed(int, android.content.Intent)">{@code onProviderInstallFailed()}</a>
method is called, and the activity can take appropriate action (such as
prompting the user to update Google Play services).</p>

<pre>/**
 * Sample activity using {&#64;link ProviderInstaller}.
 */
public class MainActivity extends Activity
    implements ProviderInstaller.ProviderInstallListener {

  private static final int ERROR_DIALOG_REQUEST_CODE = 1;

  private boolean mRetryProviderInstall;

  //Update the security provider when the activity is created.
  &#64;Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    ProviderInstaller.installIfNeededAsync(this, this);
  }

  /**
   * This method is only called if the provider is successfully updated
   * (or is already up-to-date).
   */
  &#64;Override
  protected void onProviderInstalled() {
    // Provider is up-to-date, app can make secure network calls.
  }

  /**
   * This method is called if updating fails; the error code indicates
   * whether the error is recoverable.
   */
  &#64;Override
  protected void onProviderInstallFailed(int errorCode, Intent recoveryIntent) {
    if (GooglePlayServicesUtil.isUserRecoverableError(errorCode)) {
      // Recoverable error. Show a dialog prompting the user to
      // install/update/enable Google Play services.
      GooglePlayServicesUtil.showErrorDialogFragment(
          errorCode,
          this,
          ERROR_DIALOG_REQUEST_CODE,
          new DialogInterface.OnCancelListener() {
            &#64;Override
            public void onCancel(DialogInterface dialog) {
              // The user chose not to take the recovery action
              onProviderInstallerNotAvailable();
            }
          });
    } else {
      // Google Play services is not available.
      onProviderInstallerNotAvailable();
    }
  }

  &#64;Override
  protected void onActivityResult(int requestCode, int resultCode,
      Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == ERROR_DIALOG_REQUEST_CODE) {
      // Adding a fragment via GooglePlayServicesUtil.showErrorDialogFragment
      // before the instance state is restored throws an error. So instead,
      // set a flag here, which will cause the fragment to delay until
      // onPostResume.
      mRetryProviderInstall = true;
    }
  }

  /**
   * On resume, check to see if we flagged that we need to reinstall the
   * provider.
   */
  &#64;Override
  protected void onPostResume() {
    super.onPostResult();
    if (mRetryProviderInstall) {
      // We can now safely retry installation.
      ProviderInstall.installIfNeededAsync(this, this);
    }
    mRetryProviderInstall = false;
  }

  private void onProviderInstallerNotAvailable() {
    // This is reached if the provider cannot be updated for some reason.
    // App should consider all HTTP communication to be vulnerable, and take
    // appropriate action.
  }
}
</pre>