1 files changed, 260 insertions, 0 deletions
diff --git a/services/core/java/com/android/server/updates/ConfigUpdateInstallReceiver.java b/services/core/java/com/android/server/updates/ConfigUpdateInstallReceiver.java
new file mode 100644
index 0000000..1a68fb3
--- /dev/null
+++ b/services/core/java/com/android/server/updates/ConfigUpdateInstallReceiver.java
@@ -0,0 +1,260 @@
+/*
+ * Copyright (C) 2012 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.android.server.updates;
+
+import android.content.BroadcastReceiver;
+import android.content.ContentResolver;
+import android.content.Context;
+import android.content.Intent;
+import android.provider.Settings;
+import android.util.Base64;
+import android.util.EventLog;
+import android.util.Slog;
+
+import com.android.server.EventLogTags;
+
+import java.io.ByteArrayInputStream;
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.InputStream;
+import java.io.IOException;
+import java.security.cert.CertificateException;
+import java.security.cert.CertificateFactory;
+import java.security.cert.X509Certificate;
+import java.security.MessageDigest;
+import java.security.NoSuchAlgorithmException;
+import java.security.Signature;
+
+import libcore.io.IoUtils;
+
+public class ConfigUpdateInstallReceiver extends BroadcastReceiver {
+
+    private static final String TAG = "ConfigUpdateInstallReceiver";
+
+    private static final String EXTRA_CONTENT_PATH = "CONTENT_PATH";
+    private static final String EXTRA_REQUIRED_HASH = "REQUIRED_HASH";
+    private static final String EXTRA_SIGNATURE = "SIGNATURE";
+    private static final String EXTRA_VERSION_NUMBER = "VERSION";
+
+    private static final String UPDATE_CERTIFICATE_KEY = "config_update_certificate";
+
+    protected final File updateDir;
+    protected final File updateContent;
+    protected final File updateVersion;
+
+    public ConfigUpdateInstallReceiver(String updateDir, String updateContentPath,
+                                       String updateMetadataPath, String updateVersionPath) {
+        this.updateDir = new File(updateDir);
+        this.updateContent = new File(updateDir, updateContentPath);
+        File updateMetadataDir = new File(updateDir, updateMetadataPath);
+        this.updateVersion = new File(updateMetadataDir, updateVersionPath);
+    }
+
+    @Override
+    public void onReceive(final Context context, final Intent intent) {
+        new Thread() {
+            @Override
+            public void run() {
+                try {
+                    // get the certificate from Settings.Secure
+                    X509Certificate cert = getCert(context.getContentResolver());
+                    // get the content path from the extras
+                    byte[] altContent = getAltContent(intent);
+                    // get the version from the extras
+                    int altVersion = getVersionFromIntent(intent);
+                    // get the previous value from the extras
+                    String altRequiredHash = getRequiredHashFromIntent(intent);
+                    // get the signature from the extras
+                    String altSig = getSignatureFromIntent(intent);
+                    // get the version currently being used
+                    int currentVersion = getCurrentVersion();
+                    // get the hash of the currently used value
+                    String currentHash = getCurrentHash(getCurrentContent());
+                    if (!verifyVersion(currentVersion, altVersion)) {
+                        Slog.i(TAG, "Not installing, new version is <= current version");
+                    } else if (!verifyPreviousHash(currentHash, altRequiredHash)) {
+                        EventLog.writeEvent(EventLogTags.CONFIG_INSTALL_FAILED,
+                                            "Current hash did not match required value");
+                    } else if (!verifySignature(altContent, altVersion, altRequiredHash, altSig,
+                               cert)) {
+                        EventLog.writeEvent(EventLogTags.CONFIG_INSTALL_FAILED,
+                                            "Signature did not verify");
+                    } else {
+                        // install the new content
+                        Slog.i(TAG, "Found new update, installing...");
+                        install(altContent, altVersion);
+                        Slog.i(TAG, "Installation successful");
+                        postInstall(context, intent);
+                    }
+                } catch (Exception e) {
+                    Slog.e(TAG, "Could not update content!", e);
+                    // keep the error message <= 100 chars
+                    String errMsg = e.toString();
+                    if (errMsg.length() > 100) {
+                        errMsg = errMsg.substring(0, 99);
+                    }
+                    EventLog.writeEvent(EventLogTags.CONFIG_INSTALL_FAILED, errMsg);
+                }
+            }
+        }.start();
+    }
+
+    private X509Certificate getCert(ContentResolver cr) {
+        // get the cert from settings
+        String cert = Settings.Secure.getString(cr, UPDATE_CERTIFICATE_KEY);
+        // convert it into a real certificate
+        try {
+            byte[] derCert = Base64.decode(cert.getBytes(), Base64.DEFAULT);
+            InputStream istream = new ByteArrayInputStream(derCert);
+            CertificateFactory cf = CertificateFactory.getInstance("X.509");
+            return (X509Certificate) cf.generateCertificate(istream);
+        } catch (CertificateException e) {
+            throw new IllegalStateException("Got malformed certificate from settings, ignoring");
+        }
+    }
+
+    private String getContentFromIntent(Intent i) {
+        String extraValue = i.getStringExtra(EXTRA_CONTENT_PATH);
+        if (extraValue == null) {
+            throw new IllegalStateException("Missing required content path, ignoring.");
+        }
+        return extraValue;
+    }
+
+    private int getVersionFromIntent(Intent i) throws NumberFormatException {
+        String extraValue = i.getStringExtra(EXTRA_VERSION_NUMBER);
+        if (extraValue == null) {
+            throw new IllegalStateException("Missing required version number, ignoring.");
+        }
+        return Integer.parseInt(extraValue.trim());
+    }
+
+    private String getRequiredHashFromIntent(Intent i) {
+        String extraValue = i.getStringExtra(EXTRA_REQUIRED_HASH);
+        if (extraValue == null) {
+            throw new IllegalStateException("Missing required previous hash, ignoring.");
+        }
+        return extraValue.trim();
+    }
+
+    private String getSignatureFromIntent(Intent i) {
+        String extraValue = i.getStringExtra(EXTRA_SIGNATURE);
+        if (extraValue == null) {
+            throw new IllegalStateException("Missing required signature, ignoring.");
+        }
+        return extraValue.trim();
+    }
+
+    private int getCurrentVersion() throws NumberFormatException {
+        try {
+            String strVersion = IoUtils.readFileAsString(updateVersion.getCanonicalPath()).trim();
+            return Integer.parseInt(strVersion);
+        } catch (IOException e) {
+            Slog.i(TAG, "Couldn't find current metadata, assuming first update");
+            return 0;
+        }
+    }
+
+    private byte[] getAltContent(Intent i) throws IOException {
+        return IoUtils.readFileAsByteArray(getContentFromIntent(i));
+    }
+
+    private byte[] getCurrentContent() {
+        try {
+            return IoUtils.readFileAsByteArray(updateContent.getCanonicalPath());
+        } catch (IOException e) {
+            Slog.i(TAG, "Failed to read current content, assuming first update!");
+            return null;
+        }
+    }
+
+    private static String getCurrentHash(byte[] content) {
+        if (content == null) {
+            return "0";
+        }
+        try {
+            MessageDigest dgst = MessageDigest.getInstance("SHA512");
+            byte[] fingerprint = dgst.digest(content);
+            return IntegralToString.bytesToHexString(fingerprint, false);
+        } catch (NoSuchAlgorithmException e) {
+            throw new AssertionError(e);
+        }
+    }
+
+    private boolean verifyVersion(int current, int alternative) {
+        return (current < alternative);
+    }
+
+    private boolean verifyPreviousHash(String current, String required) {
+        // this is an optional value- if the required field is NONE then we ignore it
+        if (required.equals("NONE")) {
+            return true;
+        }
+        // otherwise, verify that we match correctly
+        return current.equals(required);
+    }
+
+    private boolean verifySignature(byte[] content, int version, String requiredPrevious,
+                                   String signature, X509Certificate cert) throws Exception {
+        Signature signer = Signature.getInstance("SHA512withRSA");
+        signer.initVerify(cert);
+        signer.update(content);
+        signer.update(Long.toString(version).getBytes());
+        signer.update(requiredPrevious.getBytes());
+        return signer.verify(Base64.decode(signature.getBytes(), Base64.DEFAULT));
+    }
+
+    protected void writeUpdate(File dir, File file, byte[] content) throws IOException {
+        FileOutputStream out = null;
+        File tmp = null;
+        try {
+            // create the parents for the destination file
+            File parent = file.getParentFile();
+            parent.mkdirs();
+            // check that they were created correctly
+            if (!parent.exists()) {
+                throw new IOException("Failed to create directory " + parent.getCanonicalPath());
+            }
+            // create the temporary file
+            tmp = File.createTempFile("journal", "", dir);
+            // mark tmp -rw-r--r--
+            tmp.setReadable(true, false);
+            // write to it
+            out = new FileOutputStream(tmp);
+            out.write(content);
+            // sync to disk
+            out.getFD().sync();
+            // atomic rename
+            if (!tmp.renameTo(file)) {
+                throw new IOException("Failed to atomically rename " + file.getCanonicalPath());
+            }
+        } finally {
+            if (tmp != null) {
+                tmp.delete();
+            }
+            IoUtils.closeQuietly(out);
+        }
+    }
+
+    protected void install(byte[] content, int version) throws IOException {
+        writeUpdate(updateDir, updateContent, content);
+        writeUpdate(updateDir, updateVersion, Long.toString(version).getBytes());
+    }
+
+    protected void postInstall(Context context, Intent intent) {
+    }
+}