Tao Bao | 07342dc | 2017-01-24 15:08:21 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2018 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | |
| 17 | package com.android.server; |
| 18 | |
| 19 | import static android.os.SystemUpdateManager.KEY_STATUS; |
| 20 | import static android.os.SystemUpdateManager.STATUS_IDLE; |
| 21 | import static android.os.SystemUpdateManager.STATUS_UNKNOWN; |
| 22 | |
| 23 | import static org.xmlpull.v1.XmlPullParser.END_DOCUMENT; |
| 24 | import static org.xmlpull.v1.XmlPullParser.END_TAG; |
| 25 | import static org.xmlpull.v1.XmlPullParser.START_TAG; |
| 26 | |
| 27 | import android.Manifest; |
| 28 | import android.annotation.Nullable; |
| 29 | import android.content.Context; |
| 30 | import android.content.pm.PackageManager; |
| 31 | import android.os.Binder; |
| 32 | import android.os.Build; |
| 33 | import android.os.Bundle; |
| 34 | import android.os.Environment; |
| 35 | import android.os.ISystemUpdateManager; |
| 36 | import android.os.PersistableBundle; |
| 37 | import android.os.SystemUpdateManager; |
| 38 | import android.provider.Settings; |
| 39 | import android.util.AtomicFile; |
| 40 | import android.util.Slog; |
| 41 | import android.util.Xml; |
| 42 | |
| 43 | import com.android.internal.util.FastXmlSerializer; |
| 44 | import com.android.internal.util.XmlUtils; |
| 45 | |
| 46 | import org.xmlpull.v1.XmlPullParser; |
| 47 | import org.xmlpull.v1.XmlPullParserException; |
| 48 | import org.xmlpull.v1.XmlSerializer; |
| 49 | |
| 50 | import java.io.File; |
| 51 | import java.io.FileInputStream; |
| 52 | import java.io.FileNotFoundException; |
| 53 | import java.io.FileOutputStream; |
| 54 | import java.io.IOException; |
| 55 | import java.nio.charset.StandardCharsets; |
| 56 | |
| 57 | public class SystemUpdateManagerService extends ISystemUpdateManager.Stub { |
| 58 | |
| 59 | private static final String TAG = "SystemUpdateManagerService"; |
| 60 | |
| 61 | private static final int UID_UNKNOWN = -1; |
| 62 | |
| 63 | private static final String INFO_FILE = "system-update-info.xml"; |
| 64 | private static final int INFO_FILE_VERSION = 0; |
| 65 | private static final String TAG_INFO = "info"; |
| 66 | private static final String KEY_VERSION = "version"; |
| 67 | private static final String KEY_UID = "uid"; |
| 68 | private static final String KEY_BOOT_COUNT = "boot-count"; |
| 69 | private static final String KEY_INFO_BUNDLE = "info-bundle"; |
| 70 | |
| 71 | private final Context mContext; |
| 72 | private final AtomicFile mFile; |
| 73 | private final Object mLock = new Object(); |
| 74 | private int mLastUid = UID_UNKNOWN; |
| 75 | private int mLastStatus = STATUS_UNKNOWN; |
| 76 | |
| 77 | public SystemUpdateManagerService(Context context) { |
| 78 | mContext = context; |
| 79 | mFile = new AtomicFile(new File(Environment.getDataSystemDirectory(), INFO_FILE)); |
| 80 | |
| 81 | // Populate mLastUid and mLastStatus. |
| 82 | synchronized (mLock) { |
| 83 | loadSystemUpdateInfoLocked(); |
| 84 | } |
| 85 | } |
| 86 | |
| 87 | @Override |
| 88 | public void updateSystemUpdateInfo(PersistableBundle infoBundle) { |
| 89 | mContext.enforceCallingOrSelfPermission(Manifest.permission.RECOVERY, TAG); |
| 90 | |
| 91 | int status = infoBundle.getInt(KEY_STATUS, STATUS_UNKNOWN); |
| 92 | if (status == STATUS_UNKNOWN) { |
| 93 | Slog.w(TAG, "Invalid status info. Ignored"); |
| 94 | return; |
| 95 | } |
| 96 | |
| 97 | // There could be multiple updater apps running on a device. But only one at most should |
| 98 | // be active (i.e. with a pending update), with the rest reporting idle status. We will |
| 99 | // only accept the reported status if any of the following conditions holds: |
| 100 | // a) none has been reported before; |
| 101 | // b) the current on-file status was last reported by the same caller; |
| 102 | // c) an active update is being reported. |
| 103 | int uid = Binder.getCallingUid(); |
| 104 | if (mLastUid == UID_UNKNOWN || mLastUid == uid || status != STATUS_IDLE) { |
| 105 | synchronized (mLock) { |
| 106 | saveSystemUpdateInfoLocked(infoBundle, uid); |
| 107 | } |
| 108 | } else { |
| 109 | Slog.i(TAG, "Inactive updater reporting IDLE status. Ignored"); |
| 110 | } |
| 111 | } |
| 112 | |
| 113 | @Override |
| 114 | public Bundle retrieveSystemUpdateInfo() { |
| 115 | if (mContext.checkCallingOrSelfPermission(Manifest.permission.READ_SYSTEM_UPDATE_INFO) |
| 116 | == PackageManager.PERMISSION_DENIED |
| 117 | && mContext.checkCallingOrSelfPermission(Manifest.permission.RECOVERY) |
| 118 | == PackageManager.PERMISSION_DENIED) { |
| 119 | throw new SecurityException("Can't read system update info. Requiring " |
| 120 | + "READ_SYSTEM_UPDATE_INFO or RECOVERY permission."); |
| 121 | } |
| 122 | |
| 123 | synchronized (mLock) { |
| 124 | return loadSystemUpdateInfoLocked(); |
| 125 | } |
| 126 | } |
| 127 | |
| 128 | // Reads and validates the info file. Returns the loaded info bundle on success; or a default |
| 129 | // info bundle with UNKNOWN status. |
| 130 | private Bundle loadSystemUpdateInfoLocked() { |
| 131 | PersistableBundle loadedBundle = null; |
| 132 | try (FileInputStream fis = mFile.openRead()) { |
| 133 | XmlPullParser parser = Xml.newPullParser(); |
| 134 | parser.setInput(fis, StandardCharsets.UTF_8.name()); |
| 135 | loadedBundle = readInfoFileLocked(parser); |
| 136 | } catch (FileNotFoundException e) { |
| 137 | Slog.i(TAG, "No existing info file " + mFile.getBaseFile()); |
| 138 | } catch (XmlPullParserException e) { |
| 139 | Slog.e(TAG, "Failed to parse the info file:", e); |
| 140 | } catch (IOException e) { |
| 141 | Slog.e(TAG, "Failed to read the info file:", e); |
| 142 | } |
| 143 | |
| 144 | // Validate the loaded bundle. |
| 145 | if (loadedBundle == null) { |
| 146 | return removeInfoFileAndGetDefaultInfoBundleLocked(); |
| 147 | } |
| 148 | |
| 149 | int version = loadedBundle.getInt(KEY_VERSION, -1); |
| 150 | if (version == -1) { |
| 151 | Slog.w(TAG, "Invalid info file (invalid version). Ignored"); |
| 152 | return removeInfoFileAndGetDefaultInfoBundleLocked(); |
| 153 | } |
| 154 | |
| 155 | int lastUid = loadedBundle.getInt(KEY_UID, -1); |
| 156 | if (lastUid == -1) { |
| 157 | Slog.w(TAG, "Invalid info file (invalid UID). Ignored"); |
| 158 | return removeInfoFileAndGetDefaultInfoBundleLocked(); |
| 159 | } |
| 160 | |
| 161 | int lastBootCount = loadedBundle.getInt(KEY_BOOT_COUNT, -1); |
| 162 | if (lastBootCount == -1 || lastBootCount != getBootCount()) { |
| 163 | Slog.w(TAG, "Outdated info file. Ignored"); |
| 164 | return removeInfoFileAndGetDefaultInfoBundleLocked(); |
| 165 | } |
| 166 | |
| 167 | PersistableBundle infoBundle = loadedBundle.getPersistableBundle(KEY_INFO_BUNDLE); |
| 168 | if (infoBundle == null) { |
| 169 | Slog.w(TAG, "Invalid info file (missing info). Ignored"); |
| 170 | return removeInfoFileAndGetDefaultInfoBundleLocked(); |
| 171 | } |
| 172 | |
| 173 | int lastStatus = infoBundle.getInt(KEY_STATUS, STATUS_UNKNOWN); |
| 174 | if (lastStatus == STATUS_UNKNOWN) { |
| 175 | Slog.w(TAG, "Invalid info file (invalid status). Ignored"); |
| 176 | return removeInfoFileAndGetDefaultInfoBundleLocked(); |
| 177 | } |
| 178 | |
| 179 | // Everything looks good upon reaching this point. |
| 180 | mLastStatus = lastStatus; |
| 181 | mLastUid = lastUid; |
| 182 | return new Bundle(infoBundle); |
| 183 | } |
| 184 | |
| 185 | private void saveSystemUpdateInfoLocked(PersistableBundle infoBundle, int uid) { |
| 186 | // Wrap the incoming bundle with extra info (e.g. version, uid, boot count). We use nested |
| 187 | // PersistableBundle to avoid manually parsing XML attributes when loading the info back. |
| 188 | PersistableBundle outBundle = new PersistableBundle(); |
| 189 | outBundle.putPersistableBundle(KEY_INFO_BUNDLE, infoBundle); |
| 190 | outBundle.putInt(KEY_VERSION, INFO_FILE_VERSION); |
| 191 | outBundle.putInt(KEY_UID, uid); |
| 192 | outBundle.putInt(KEY_BOOT_COUNT, getBootCount()); |
| 193 | |
| 194 | // Only update the info on success. |
| 195 | if (writeInfoFileLocked(outBundle)) { |
| 196 | mLastUid = uid; |
| 197 | mLastStatus = infoBundle.getInt(KEY_STATUS); |
| 198 | } |
| 199 | } |
| 200 | |
| 201 | // Performs I/O work only, without validating the loaded info. |
| 202 | @Nullable |
| 203 | private PersistableBundle readInfoFileLocked(XmlPullParser parser) |
| 204 | throws XmlPullParserException, IOException { |
| 205 | int type; |
| 206 | while ((type = parser.next()) != END_DOCUMENT) { |
| 207 | if (type == START_TAG && TAG_INFO.equals(parser.getName())) { |
| 208 | return PersistableBundle.restoreFromXml(parser); |
| 209 | } |
| 210 | } |
| 211 | return null; |
| 212 | } |
| 213 | |
| 214 | private boolean writeInfoFileLocked(PersistableBundle outBundle) { |
| 215 | FileOutputStream fos = null; |
| 216 | try { |
| 217 | fos = mFile.startWrite(); |
| 218 | |
| 219 | XmlSerializer out = new FastXmlSerializer(); |
| 220 | out.setOutput(fos, StandardCharsets.UTF_8.name()); |
| 221 | out.startDocument(null, true); |
| 222 | |
| 223 | out.startTag(null, TAG_INFO); |
| 224 | outBundle.saveToXml(out); |
| 225 | out.endTag(null, TAG_INFO); |
| 226 | |
| 227 | out.endDocument(); |
| 228 | mFile.finishWrite(fos); |
| 229 | return true; |
| 230 | } catch (IOException | XmlPullParserException e) { |
| 231 | Slog.e(TAG, "Failed to save the info file:", e); |
| 232 | if (fos != null) { |
| 233 | mFile.failWrite(fos); |
| 234 | } |
| 235 | } |
| 236 | return false; |
| 237 | } |
| 238 | |
| 239 | private Bundle removeInfoFileAndGetDefaultInfoBundleLocked() { |
| 240 | if (mFile.exists()) { |
| 241 | Slog.i(TAG, "Removing info file"); |
| 242 | mFile.delete(); |
| 243 | } |
| 244 | |
| 245 | mLastStatus = STATUS_UNKNOWN; |
| 246 | mLastUid = UID_UNKNOWN; |
| 247 | Bundle infoBundle = new Bundle(); |
| 248 | infoBundle.putInt(KEY_STATUS, STATUS_UNKNOWN); |
| 249 | return infoBundle; |
| 250 | } |
| 251 | |
| 252 | private int getBootCount() { |
| 253 | return Settings.Global.getInt(mContext.getContentResolver(), Settings.Global.BOOT_COUNT, 0); |
| 254 | } |
| 255 | } |