Keyservers: Dont follow redirects, pin pgp.mit.edu, check for pinned cert on add (OKC-01-018)

5 files changed, 101 insertions, 94 deletions

diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/KeychainApplication.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/KeychainApplication.java
index 311ef2d3b..45d81749a 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/KeychainApplication.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/KeychainApplication.java
@@ -91,14 +91,15 @@ public class KeychainApplication extends Application {
         }
 
         brandGlowEffect(getApplicationContext(),
-            FormattingUtils.getColorFromAttr(getApplicationContext(), R.attr.colorPrimary));
+                FormattingUtils.getColorFromAttr(getApplicationContext(), R.attr.colorPrimary));
 
         setupAccountAsNeeded(this);
 
         // Update keyserver list as needed
         Preferences.getPreferences(this).upgradePreferences(this);
 
-        TlsHelper.addStaticCA("pool.sks-keyservers.net", getAssets(), "sks-keyservers.netCA.cer");
+        TlsHelper.addPinnedCertificate("hkps.pool.sks-keyservers.net", getAssets(), "hkps.pool.sks-keyservers.net.CA.cer");
+        TlsHelper.addPinnedCertificate("pgp.mit.edu", getAssets(), "pgp.mit.edu.cer");
 
         TemporaryStorageProvider.cleanUp(this);
 
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/keyimport/HkpKeyserver.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/keyimport/HkpKeyserver.java
index 558b8ce7d..5683decdf 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/keyimport/HkpKeyserver.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/keyimport/HkpKeyserver.java
@@ -204,11 +204,15 @@ public class HkpKeyserver extends Keyserver {
         OkHttpClient client = new OkHttpClient();
 
         try {
-            TlsHelper.pinCertificateIfNecessary(client, url);
+            TlsHelper.usePinnedCertificateIfAvailable(client, url);
         } catch (TlsHelper.TlsHelperException e) {
             Log.w(Constants.TAG, e);
         }
 
+        // don't follow any redirects
+        client.setFollowRedirects(false);
+        client.setFollowSslRedirects(false);
+
         if (proxy != null) {
             client.setProxy(proxy);
             client.setConnectTimeout(30000, TimeUnit.MILLISECONDS);
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/SettingsKeyserverFragment.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/SettingsKeyserverFragment.java
index d8edbe4f8..5a8ab36bc 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/SettingsKeyserverFragment.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/SettingsKeyserverFragment.java
@@ -155,7 +155,7 @@ public class SettingsKeyserverFragment extends Fragment implements RecyclerItemC
                                 data.getBoolean(AddEditKeyserverDialogFragment.MESSAGE_VERIFIED);
                         if (verified) {
                             Notify.create(getActivity(),
-                                    R.string.add_keyserver_verified, Notify.Style.OK).show();
+                                    R.string.add_keyserver_connection_verified, Notify.Style.OK).show();
                         } else {
                             Notify.create(getActivity(),
                                     R.string.add_keyserver_without_verification,
@@ -177,26 +177,6 @@ public class SettingsKeyserverFragment extends Fragment implements RecyclerItemC
                         }
                         break;
                     }
-                    case AddEditKeyserverDialogFragment.MESSAGE_VERIFICATION_FAILED: {
-                        AddEditKeyserverDialogFragment.FailureReason failureReason =
-                                (AddEditKeyserverDialogFragment.FailureReason) data.getSerializable(
-                                        AddEditKeyserverDialogFragment.MESSAGE_FAILURE_REASON);
-                        switch (failureReason) {
-                            case CONNECTION_FAILED: {
-                                Notify.create(getActivity(),
-                                        R.string.add_keyserver_connection_failed,
-                                        Notify.Style.ERROR).show();
-                                break;
-                            }
-                            case INVALID_URL: {
-                                Notify.create(getActivity(),
-                                        R.string.add_keyserver_invalid_url,
-                                        Notify.Style.ERROR).show();
-                                break;
-                            }
-                        }
-                        break;
-                    }
                 }
             }
         };
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/dialog/AddEditKeyserverDialogFragment.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/dialog/AddEditKeyserverDialogFragment.java
index 47bc7dfda..3d96f3c6d 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/dialog/AddEditKeyserverDialogFragment.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/ui/dialog/AddEditKeyserverDialogFragment.java
@@ -24,6 +24,7 @@ import java.net.URI;
 import java.net.URISyntaxException;
 
 import android.app.Activity;
+import android.support.design.widget.TextInputLayout;
 import android.support.v7.app.AlertDialog;
 import android.app.Dialog;
 import android.app.ProgressDialog;
@@ -44,6 +45,7 @@ import android.view.inputmethod.EditorInfo;
 import android.view.inputmethod.InputMethodManager;
 import android.widget.Button;
 import android.widget.CheckBox;
+import android.widget.CompoundButton;
 import android.widget.EditText;
 import android.widget.TextView;
 import android.widget.TextView.OnEditorActionListener;
@@ -54,6 +56,7 @@ import com.squareup.okhttp.Request;
 import org.sufficientlysecure.keychain.Constants;
 import org.sufficientlysecure.keychain.R;
 import org.sufficientlysecure.keychain.keyimport.HkpKeyserver;
+import org.sufficientlysecure.keychain.ui.util.Notify;
 import org.sufficientlysecure.keychain.util.Log;
 import org.sufficientlysecure.keychain.util.Preferences;
 import org.sufficientlysecure.keychain.util.TlsHelper;
@@ -68,11 +71,9 @@ public class AddEditKeyserverDialogFragment extends DialogFragment implements On
     private static final String ARG_KEYSERVER = "arg_keyserver";
 
     public static final int MESSAGE_OKAY = 1;
-    public static final int MESSAGE_VERIFICATION_FAILED = 2;
 
     public static final String MESSAGE_KEYSERVER = "new_keyserver";
     public static final String MESSAGE_VERIFIED = "verified";
-    public static final String MESSAGE_FAILURE_REASON = "failure_reason";
     public static final String MESSAGE_KEYSERVER_DELETED = "keyserver_deleted";
     public static final String MESSAGE_DIALOG_ACTION = "message_dialog_action";
     public static final String MESSAGE_EDIT_POSITION = "keyserver_edited_position";
@@ -82,7 +83,9 @@ public class AddEditKeyserverDialogFragment extends DialogFragment implements On
     private int mPosition;
 
     private EditText mKeyserverEditText;
+    private TextInputLayout mKeyserverEditTextLayout;
     private CheckBox mVerifyKeyserverCheckBox;
+    private CheckBox mOnlyTrustedKeyserverCheckBox;
 
     public enum DialogAction {
         ADD,
@@ -91,7 +94,8 @@ public class AddEditKeyserverDialogFragment extends DialogFragment implements On
 
     public enum FailureReason {
         INVALID_URL,
-        CONNECTION_FAILED
+        CONNECTION_FAILED,
+        NO_PINNED_CERTIFICATE
     }
 
     public static AddEditKeyserverDialogFragment newInstance(Messenger messenger,
@@ -126,7 +130,15 @@ public class AddEditKeyserverDialogFragment extends DialogFragment implements On
         alert.setView(view);
 
         mKeyserverEditText = (EditText) view.findViewById(R.id.keyserver_url_edit_text);
-        mVerifyKeyserverCheckBox = (CheckBox) view.findViewById(R.id.verify_keyserver_checkbox);
+        mKeyserverEditTextLayout = (TextInputLayout) view.findViewById(R.id.keyserver_url_edit_text_layout);
+        mVerifyKeyserverCheckBox = (CheckBox) view.findViewById(R.id.verify_connection_checkbox);
+        mOnlyTrustedKeyserverCheckBox = (CheckBox) view.findViewById(R.id.only_trusted_keyserver_checkbox);
+        mVerifyKeyserverCheckBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
+            @Override
+            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
+                mOnlyTrustedKeyserverCheckBox.setEnabled(isChecked);
+            }
+        });
 
         switch (mDialogAction) {
             case ADD: {
@@ -212,6 +224,8 @@ public class AddEditKeyserverDialogFragment extends DialogFragment implements On
             positiveButton.setOnClickListener(new View.OnClickListener() {
                 @Override
                 public void onClick(View v) {
+                    mKeyserverEditTextLayout.setErrorEnabled(false);
+
                     // behaviour same for edit and add
                     final String keyserverUrl = mKeyserverEditText.getText().toString();
                     if (mVerifyKeyserverCheckBox.isChecked()) {
@@ -220,13 +234,20 @@ public class AddEditKeyserverDialogFragment extends DialogFragment implements On
                         OrbotHelper.DialogActions dialogActions = new OrbotHelper.DialogActions() {
                             @Override
                             public void onOrbotStarted() {
-                                verifyConnection(keyserverUrl,
-                                        proxyPrefs.parcelableProxy.getProxy());
+                                verifyConnection(
+                                        keyserverUrl,
+                                        proxyPrefs.parcelableProxy.getProxy(),
+                                        mOnlyTrustedKeyserverCheckBox.isChecked()
+                                );
                             }
 
                             @Override
                             public void onNeutralButton() {
-                                verifyConnection(keyserverUrl, null);
+                                verifyConnection(
+                                        keyserverUrl,
+                                        null,
+                                        mOnlyTrustedKeyserverCheckBox.isChecked()
+                                );
                             }
 
                             @Override
@@ -236,7 +257,11 @@ public class AddEditKeyserverDialogFragment extends DialogFragment implements On
                         };
 
                         if (OrbotHelper.putOrbotInRequiredState(dialogActions, getActivity())) {
-                            verifyConnection(keyserverUrl, proxyPrefs.parcelableProxy.getProxy());
+                            verifyConnection(
+                                    keyserverUrl,
+                                    proxyPrefs.parcelableProxy.getProxy(),
+                                    mOnlyTrustedKeyserverCheckBox.isChecked()
+                            );
                         }
                     } else {
                         dismiss();
@@ -272,14 +297,28 @@ public class AddEditKeyserverDialogFragment extends DialogFragment implements On
         sendMessageToHandler(MESSAGE_OKAY, data);
     }
 
-    public void verificationFailed(FailureReason reason) {
-        Bundle data = new Bundle();
-        data.putSerializable(MESSAGE_FAILURE_REASON, reason);
+    public void verificationFailed(FailureReason failureReason) {
+        switch (failureReason) {
+            case CONNECTION_FAILED: {
+                mKeyserverEditTextLayout.setError(
+                        getString(R.string.add_keyserver_connection_failed));
+                break;
+            }
+            case INVALID_URL: {
+                mKeyserverEditTextLayout.setError(
+                        getString(R.string.add_keyserver_invalid_url));
+                break;
+            }
+            case NO_PINNED_CERTIFICATE: {
+                mKeyserverEditTextLayout.setError(
+                        getString(R.string.add_keyserver_keyserver_not_trusted));
+                break;
+            }
+        }
 
-        sendMessageToHandler(MESSAGE_VERIFICATION_FAILED, data);
     }
 
-    public void verifyConnection(String keyserver, final Proxy proxy) {
+    public void verifyConnection(String keyserver, final Proxy proxy, final boolean onlyTrustedKeyserver) {
 
         new AsyncTask<String, Void, FailureReason>() {
             ProgressDialog mProgressDialog;
@@ -288,7 +327,7 @@ public class AddEditKeyserverDialogFragment extends DialogFragment implements On
             @Override
             protected void onPreExecute() {
                 mProgressDialog = new ProgressDialog(getActivity());
-                mProgressDialog.setMessage(getString(R.string.progress_verifying_keyserver_url));
+                mProgressDialog.setMessage(getString(R.string.progress_verifying_keyserver_connection));
                 mProgressDialog.setCancelable(false);
                 mProgressDialog.show();
             }
@@ -316,7 +355,18 @@ public class AddEditKeyserverDialogFragment extends DialogFragment implements On
                     Log.d("Converted URL", newKeyserver.toString());
 
                     OkHttpClient client = HkpKeyserver.getClient(newKeyserver.toURL(), proxy);
-                    TlsHelper.pinCertificateIfNecessary(client, newKeyserver.toURL());
+
+                    // don't follow any redirects
+                    client.setFollowRedirects(false);
+                    client.setFollowSslRedirects(false);
+
+                    if (onlyTrustedKeyserver
+                            && !TlsHelper.usePinnedCertificateIfAvailable(client, newKeyserver.toURL())) {
+                        Log.w(Constants.TAG, "No pinned certificate for this host in OpenKeychain's assets.");
+                        reason = FailureReason.NO_PINNED_CERTIFICATE;
+                        return reason;
+                    }
+
                     client.newCall(new Request.Builder().url(newKeyserver.toURL()).build()).execute();
                 } catch (TlsHelper.TlsHelperException e) {
                     reason = FailureReason.CONNECTION_FAILED;
diff --git a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/TlsHelper.java b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/TlsHelper.java
index d1d1ada2a..1492abdeb 100644
--- a/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/TlsHelper.java
+++ b/OpenKeychain/src/main/java/org/sufficientlysecure/keychain/util/TlsHelper.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2013-2014 Dominik Schürmann <dominik@dominikschuermann.de>
+ * Copyright (C) 2013-2015 Dominik Schürmann <dominik@dominikschuermann.de>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -20,6 +20,7 @@ package org.sufficientlysecure.keychain.util;
 import android.content.res.AssetManager;
 
 import com.squareup.okhttp.OkHttpClient;
+
 import org.sufficientlysecure.keychain.Constants;
 
 import java.io.ByteArrayInputStream;
@@ -37,7 +38,6 @@ import java.security.cert.CertificateFactory;
 import java.util.HashMap;
 import java.util.Map;
 
-import javax.net.ssl.HttpsURLConnection;
 import javax.net.ssl.SSLContext;
 import javax.net.ssl.TrustManagerFactory;
 
@@ -49,15 +49,14 @@ public class TlsHelper {
         }
     }
 
-    private static Map<String, byte[]> sStaticCA = new HashMap<>();
-
-    public static void addStaticCA(String domain, byte[] certificate) {
-        sStaticCA.put(domain, certificate);
-    }
+    private static Map<String, byte[]> sPinnedCertificates = new HashMap<>();
 
-    public static void addStaticCA(String domain, AssetManager assetManager, String name) {
+    /**
+     * Add certificate from assets to pinned certificate map.
+     */
+    public static void addPinnedCertificate(String host, AssetManager assetManager, String cerFilename) {
         try {
-            InputStream is = assetManager.open(name);
+            InputStream is = assetManager.open(cerFilename);
             ByteArrayOutputStream baos = new ByteArrayOutputStream();
             int reads = is.read();
 
@@ -68,27 +67,36 @@ public class TlsHelper {
 
             is.close();
 
-            addStaticCA(domain, baos.toByteArray());
+            sPinnedCertificates.put(host, baos.toByteArray());
         } catch (IOException e) {
             Log.w(Constants.TAG, e);
         }
     }
 
-    public static void pinCertificateIfNecessary(OkHttpClient client, URL url) throws TlsHelperException, IOException {
+    /**
+     * Use pinned certificate for OkHttpClient if we have one.
+     *
+     * @return true, if certificate is available, false if not
+     * @throws TlsHelperException
+     * @throws IOException
+     */
+    public static boolean usePinnedCertificateIfAvailable(OkHttpClient client, URL url) throws TlsHelperException, IOException {
         if (url.getProtocol().equals("https")) {
-            for (String domain : sStaticCA.keySet()) {
-                if (url.getHost().endsWith(domain)) {
-                    pinCertificate(sStaticCA.get(domain), client);
+            // use certificate PIN from assets if we have one
+            for (String host : sPinnedCertificates.keySet()) {
+                if (url.getHost().endsWith(host)) {
+                    pinCertificate(sPinnedCertificates.get(host), client);
+                    return true;
                 }
             }
         }
+        return false;
     }
 
     /**
      * Modifies the client to accept only requests with a given certificate. Applies to all URLs requested by the
      * client.
      * Therefore a client that is pinned this way should be used to only make requests to URLs with passed certificate.
-     * TODO: Refactor - More like SSH StrictHostKeyChecking than pinning?
      *
      * @param certificate certificate to pin
      * @param client      OkHttpClient to enforce pinning on
@@ -97,8 +105,10 @@ public class TlsHelper {
      */
     private static void pinCertificate(byte[] certificate, OkHttpClient client)
             throws TlsHelperException, IOException {
-        // We don't use OkHttp's CertificatePinner since it depends on a TrustManager to verify it too. Refer to
-        // note at end of description: http://square.github.io/okhttp/javadoc/com/squareup/okhttp/CertificatePinner.html
+        // We don't use OkHttp's CertificatePinner since it can not be used to pin self-signed
+        // certificate if such certificate is not accepted by TrustManager.
+        // (Refer to note at end of description:
+        // http://square.github.io/okhttp/javadoc/com/squareup/okhttp/CertificatePinner.html )
         // Creating our own TrustManager that trusts only our certificate eliminates the need for certificate pinning
         try {
             // Load CA
@@ -126,42 +136,4 @@ public class TlsHelper {
         }
     }
 
-    /**
-     * Opens a Connection that will only accept certificates signed with a specific CA and skips common name check.
-     * This is required for some distributed Keyserver networks like sks-keyservers.net
-     *
-     * @param certificate The X.509 certificate used to sign the servers certificate
-     * @param url         Connection target
-     */
-    public static HttpsURLConnection openCAConnection(byte[] certificate, URL url)
-            throws TlsHelperException, IOException {
-        try {
-            // Load CA
-            CertificateFactory cf = CertificateFactory.getInstance("X.509");
-            Certificate ca = cf.generateCertificate(new ByteArrayInputStream(certificate));
-
-            // Create a KeyStore containing our trusted CAs
-            String keyStoreType = KeyStore.getDefaultType();
-            KeyStore keyStore = KeyStore.getInstance(keyStoreType);
-            keyStore.load(null, null);
-            keyStore.setCertificateEntry("ca", ca);
-
-            // Create a TrustManager that trusts the CAs in our KeyStore
-            String tmfAlgorithm = TrustManagerFactory.getDefaultAlgorithm();
-            TrustManagerFactory tmf = TrustManagerFactory.getInstance(tmfAlgorithm);
-            tmf.init(keyStore);
-
-            // Create an SSLContext that uses our TrustManager
-            SSLContext context = SSLContext.getInstance("TLS");
-            context.init(null, tmf.getTrustManagers(), null);
-
-            // Tell the URLConnection to use a SocketFactory from our SSLContext
-            HttpsURLConnection urlConnection = (HttpsURLConnection) url.openConnection();
-            urlConnection.setSSLSocketFactory(context.getSocketFactory());
-
-            return urlConnection;
-        } catch (CertificateException | KeyManagementException | KeyStoreException | NoSuchAlgorithmException e) {
-            throw new TlsHelperException(e);
-        }
-    }
 }