Merge "Add ConfigUpdater service for CT logs"

            </intent-filter>

        </receiver>

        <receiver android:name="com.android.server.updates.CertificateTransparencyLogInstallReceiver"

                android:permission="android.permission.UPDATE_CONFIG">

            <intent-filter>

                <action android:name="android.intent.action.UPDATE_CT_LOGS" />

                <data android:scheme="content" android:host="*" android:mimeType="*/*" />

            </intent-filter>

        </receiver>

        <receiver android:name="com.android.server.MasterClearReceiver"

            android:permission="android.permission.MASTER_CLEAR">

            <intent-filter

/*

 * Copyright (C) 2016 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 com.android.internal.util.HexDump;

import android.os.FileUtils;

import android.system.Os;

import android.system.ErrnoException;

import android.util.Base64;

import android.util.Slog;

import java.io.File;

import java.io.FileFilter;

import java.io.FileOutputStream;

import java.io.IOException;

import java.io.OutputStreamWriter;

import java.io.StringBufferInputStream;

import java.nio.charset.StandardCharsets;

import java.security.MessageDigest;

import java.security.PublicKey;

import java.security.NoSuchAlgorithmException;

import org.json.JSONArray;

import org.json.JSONException;

import org.json.JSONObject;

public class CertificateTransparencyLogInstallReceiver extends ConfigUpdateInstallReceiver {

    private static final String TAG = "CTLogInstallReceiver";

    private static final String LOGDIR_PREFIX = "logs-";

    public CertificateTransparencyLogInstallReceiver() {

        super("/data/misc/keychain/trusted_ct_logs/", "ct_logs", "metadata/", "version");

    }

    @Override

    protected void install(byte[] content, int version) throws IOException {

        /* Install is complicated here because we translate the input, which is a JSON file

         * containing log information to a directory with a file per log. To support atomically

         * replacing the old configuration directory with the new there's a bunch of steps. We

         * create a new directory with the logs and then do an atomic update of the current symlink

         * to point to the new directory.

         */

        // 1. Ensure that the update dir exists and is readable

        updateDir.mkdir();

        if (!updateDir.isDirectory()) {

            throw new IOException("Unable to make directory " + updateDir.getCanonicalPath());

        }

        if (!updateDir.setReadable(true, false)) {

            throw new IOException("Unable to set permissions on " +

                    updateDir.getCanonicalPath());

        }

        File currentSymlink = new File(updateDir, "current");

        File newVersion = new File(updateDir, LOGDIR_PREFIX + String.valueOf(version));

        File oldDirectory;

        // 2. Handle the corner case where the new directory already exists.

        if (newVersion.exists()) {

            // If the symlink has already been updated then the update died between steps 7 and 8

            // and so we cannot delete the directory since its in use. Instead just bump the version

            // and return.

            if (newVersion.getCanonicalPath().equals(currentSymlink.getCanonicalPath())) {

                writeUpdate(updateDir, updateVersion, Long.toString(version).getBytes());

                deleteOldLogDirectories();

                return;

            } else {

                FileUtils.deleteContentsAndDir(newVersion);

            }

        }

        try {

            // 3. Create /data/misc/keychain/trusted_ct_logs/<new_version>/ .

            newVersion.mkdir();

            if (!newVersion.isDirectory()) {

                throw new IOException("Unable to make directory " + newVersion.getCanonicalPath());

            }

            if (!newVersion.setReadable(true, false)) {

                throw new IOException("Failed to set " +newVersion.getCanonicalPath() +

                        " readable");

            }

            // 4. For each log in the log file create the corresponding file in <new_version>/ .

            try {

                JSONObject json = new JSONObject(new String(content, StandardCharsets.UTF_8));

                JSONArray logs = json.getJSONArray("logs");

                for (int i = 0; i < logs.length(); i++) {

                    JSONObject log = logs.getJSONObject(i);

                    installLog(newVersion, log);

                }

            } catch (JSONException e) {

                throw new IOException("Failed to parse logs", e);

            }

            // 5. Create the temp symlink. We'll rename this to the target symlink to get an atomic

            // update.

            File tempSymlink = new File(updateDir, "new_symlink");

            try {

                Os.symlink(newVersion.getCanonicalPath(), tempSymlink.getCanonicalPath());

            } catch (ErrnoException e) {

                throw new IOException("Failed to create symlink", e);

            }

            // 6. Update the symlink target, this is the actual update step.

            tempSymlink.renameTo(currentSymlink.getAbsoluteFile());

        } catch (IOException | RuntimeException e) {

            FileUtils.deleteContentsAndDir(newVersion);

            throw e;

        }

        Slog.i(TAG, "CT log directory updated to " + newVersion.getAbsolutePath());

        // 7. Update the current version information

        writeUpdate(updateDir, updateVersion, Long.toString(version).getBytes());

        // 8. Cleanup

        deleteOldLogDirectories();

    }

    private void installLog(File directory, JSONObject logObject) throws IOException {

        try {

            String logFilename = getLogFileName(logObject.getString("key"));

            File file = new File(directory, logFilename);

            try (OutputStreamWriter out =

                    new OutputStreamWriter(new FileOutputStream(file), StandardCharsets.UTF_8)) {

                writeLogEntry(out, "key", logObject.getString("key"));

                writeLogEntry(out, "url", logObject.getString("url"));

                writeLogEntry(out, "description", logObject.getString("description"));

            }

            if (!file.setReadable(true, false)) {

                throw new IOException("Failed to set permissions on " + file.getCanonicalPath());

            }

        } catch (JSONException e) {

            throw new IOException("Failed to parse log", e);

        }

    }

    /**

     * Get the filename for a log based on its public key. This must be kept in sync with

     * org.conscrypt.ct.CTLogStoreImpl.

     */

    private String getLogFileName(String base64PublicKey) {

        byte[] keyBytes = Base64.decode(base64PublicKey, Base64.DEFAULT);

        try {

            byte[] id = MessageDigest.getInstance("SHA-256").digest(keyBytes);

            return HexDump.toHexString(id, false);

        } catch (NoSuchAlgorithmException e) {

            // SHA-256 is guaranteed to be available.

            throw new RuntimeException(e);

        }

    }

    private void writeLogEntry(OutputStreamWriter out, String key, String value)

            throws IOException {

        out.write(key + ":" + value + "\n");

    }

    private void deleteOldLogDirectories() throws IOException {

        if (!updateDir.exists()) {

            return;

        }

        File currentTarget = new File(updateDir, "current").getCanonicalFile();

        FileFilter filter = new FileFilter() {

            @Override

            public boolean accept(File file) {

                return !currentTarget.equals(file) && file.getName().startsWith(LOGDIR_PREFIX);

            }

        };

        for (File f : updateDir.listFiles(filter)) {

            FileUtils.deleteContentsAndDir(f);

        }

    }

}