David Anderson | 28dea68 | 2019-02-20 13:37:51 -0800 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2019 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.locksettings; |
| 18 | |
| 19 | import android.os.SystemProperties; |
| 20 | import android.util.Slog; |
| 21 | |
| 22 | import com.android.internal.annotations.VisibleForTesting; |
| 23 | |
| 24 | import java.io.File; |
| 25 | import java.io.FileInputStream; |
| 26 | import java.io.FileOutputStream; |
| 27 | import java.io.IOException; |
| 28 | import java.io.InputStream; |
| 29 | import java.io.OutputStream; |
| 30 | import java.nio.file.Paths; |
| 31 | import java.util.Collections; |
| 32 | import java.util.HashMap; |
| 33 | import java.util.HashSet; |
| 34 | import java.util.Map; |
| 35 | import java.util.Properties; |
| 36 | import java.util.Set; |
| 37 | |
| 38 | /** |
| 39 | * A class that maintains a mapping of which password slots are used by alternate OS images when |
| 40 | * dual-booting a device. Currently, slots can either be owned by the host OS or a live GSI. |
| 41 | * This mapping is stored in /metadata/password_slots/slot_map using Java Properties. |
| 42 | * |
| 43 | * If a /metadata partition does not exist, GSIs are not supported, and PasswordSlotManager will |
| 44 | * simply not persist the slot mapping. |
| 45 | */ |
| 46 | public class PasswordSlotManager { |
| 47 | private static final String TAG = "PasswordSlotManager"; |
| 48 | |
| 49 | private static final String GSI_RUNNING_PROP = "ro.gsid.image_running"; |
| 50 | private static final String SLOT_MAP_DIR = "/metadata/password_slots"; |
| 51 | |
| 52 | // This maps each used password slot to the OS image that created it. Password slots are |
| 53 | // integer keys/indices into secure storage. The OS image is recorded as a string. The factory |
| 54 | // image is "host" and GSIs are "gsi<N>" where N >= 1. |
| 55 | private final Map<Integer, String> mSlotMap; |
| 56 | |
| 57 | public PasswordSlotManager() { |
| 58 | mSlotMap = loadSlotMap(); |
| 59 | } |
| 60 | |
| 61 | @VisibleForTesting |
| 62 | protected String getSlotMapDir() { |
| 63 | return SLOT_MAP_DIR; |
| 64 | } |
| 65 | |
| 66 | @VisibleForTesting |
| 67 | protected int getGsiImageNumber() { |
| 68 | return SystemProperties.getInt(GSI_RUNNING_PROP, 0); |
| 69 | } |
| 70 | |
| 71 | /** |
| 72 | * Notify the manager of which slots are definitively in use by the current OS image. |
| 73 | * |
| 74 | * @throws RuntimeException |
| 75 | */ |
| 76 | public void refreshActiveSlots(Set<Integer> activeSlots) throws RuntimeException { |
| 77 | // Update which slots are owned by the current image. |
| 78 | final HashSet<Integer> slotsToDelete = new HashSet<Integer>(); |
| 79 | for (Map.Entry<Integer, String> entry : mSlotMap.entrySet()) { |
| 80 | // Delete possibly stale entries for the current image. |
| 81 | if (entry.getValue().equals(getMode())) { |
| 82 | slotsToDelete.add(entry.getKey()); |
| 83 | } |
| 84 | } |
| 85 | for (Integer slot : slotsToDelete) { |
| 86 | mSlotMap.remove(slot); |
| 87 | } |
| 88 | |
| 89 | // Add slots for the current image. |
| 90 | for (Integer slot : activeSlots) { |
| 91 | mSlotMap.put(slot, getMode()); |
| 92 | } |
| 93 | |
| 94 | saveSlotMap(); |
| 95 | } |
| 96 | |
| 97 | /** |
| 98 | * Mark the given slot as in use by the current OS image. |
| 99 | * |
| 100 | * @throws RuntimeException |
| 101 | */ |
| 102 | public void markSlotInUse(int slot) throws RuntimeException { |
| 103 | if (mSlotMap.containsKey(slot) && !mSlotMap.get(slot).equals(getMode())) { |
| 104 | throw new RuntimeException("password slot " + slot + " is not available"); |
| 105 | } |
| 106 | mSlotMap.put(slot, getMode()); |
| 107 | saveSlotMap(); |
| 108 | } |
| 109 | |
| 110 | /** |
| 111 | * Mark the given slot as no longer in use by the current OS image. |
| 112 | * |
| 113 | * @throws RuntimeException |
| 114 | */ |
| 115 | public void markSlotDeleted(int slot) throws RuntimeException { |
| 116 | if (mSlotMap.containsKey(slot) && mSlotMap.get(slot) != getMode()) { |
| 117 | throw new RuntimeException("password slot " + slot + " cannot be deleted"); |
| 118 | } |
| 119 | mSlotMap.remove(slot); |
| 120 | saveSlotMap(); |
| 121 | } |
| 122 | |
| 123 | /** |
| 124 | * Return the set of slots used across all OS images. |
| 125 | * |
| 126 | * @return Integer set of all used slots. |
| 127 | */ |
| 128 | public Set<Integer> getUsedSlots() { |
| 129 | return Collections.unmodifiableSet(mSlotMap.keySet()); |
| 130 | } |
| 131 | |
| 132 | private File getSlotMapFile() { |
| 133 | return Paths.get(getSlotMapDir(), "slot_map").toFile(); |
| 134 | } |
| 135 | |
| 136 | private String getMode() { |
| 137 | int gsiIndex = getGsiImageNumber(); |
| 138 | if (gsiIndex > 0) { |
| 139 | return "gsi" + gsiIndex; |
| 140 | } |
| 141 | return "host"; |
| 142 | } |
| 143 | |
| 144 | @VisibleForTesting |
| 145 | protected Map<Integer, String> loadSlotMap(InputStream stream) throws IOException { |
| 146 | final HashMap<Integer, String> map = new HashMap<Integer, String>(); |
| 147 | final Properties props = new Properties(); |
| 148 | props.load(stream); |
| 149 | for (String slotString : props.stringPropertyNames()) { |
| 150 | final int slot = Integer.parseInt(slotString); |
| 151 | final String owner = props.getProperty(slotString); |
| 152 | map.put(slot, owner); |
| 153 | } |
| 154 | return map; |
| 155 | } |
| 156 | |
| 157 | private Map<Integer, String> loadSlotMap() { |
| 158 | // It's okay if the file doesn't exist. |
| 159 | final File file = getSlotMapFile(); |
| 160 | if (file.exists()) { |
| 161 | try (FileInputStream stream = new FileInputStream(file)) { |
| 162 | return loadSlotMap(stream); |
| 163 | } catch (Exception e) { |
| 164 | Slog.e(TAG, "Could not load slot map file", e); |
| 165 | } |
| 166 | } |
| 167 | return new HashMap<Integer, String>(); |
| 168 | } |
| 169 | |
| 170 | @VisibleForTesting |
| 171 | protected void saveSlotMap(OutputStream stream) throws IOException { |
| 172 | final Properties props = new Properties(); |
| 173 | for (Map.Entry<Integer, String> entry : mSlotMap.entrySet()) { |
| 174 | props.setProperty(entry.getKey().toString(), entry.getValue()); |
| 175 | } |
| 176 | props.store(stream, ""); |
| 177 | } |
| 178 | |
| 179 | private void saveSlotMap() { |
| 180 | if (!getSlotMapFile().getParentFile().exists()) { |
| 181 | Slog.w(TAG, "Not saving slot map, " + getSlotMapDir() + " does not exist"); |
| 182 | return; |
| 183 | } |
| 184 | |
| 185 | try (FileOutputStream fos = new FileOutputStream(getSlotMapFile())) { |
| 186 | saveSlotMap(fos); |
| 187 | } catch (IOException e) { |
| 188 | Slog.e(TAG, "failed to save password slot map", e); |
| 189 | } |
| 190 | } |
| 191 | } |