Aurimas Liutikas | 88c7ff1 | 2023-08-10 12:42:26 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2021 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.compat.overrides; |
| 18 | |
| 19 | import static android.content.pm.PackageManager.CERT_INPUT_SHA256; |
| 20 | import static android.content.pm.PackageManager.MATCH_ANY_USER; |
| 21 | |
| 22 | import static java.util.Collections.emptyMap; |
| 23 | import static java.util.Collections.emptySet; |
| 24 | |
| 25 | import android.annotation.Nullable; |
| 26 | import android.app.compat.PackageOverride; |
| 27 | import android.content.pm.ApplicationInfo; |
| 28 | import android.content.pm.PackageManager; |
| 29 | import android.util.ArrayMap; |
| 30 | import android.util.ArraySet; |
| 31 | import android.util.KeyValueListParser; |
| 32 | import android.util.Pair; |
| 33 | import android.util.Slog; |
| 34 | |
| 35 | import libcore.util.HexEncoding; |
| 36 | |
| 37 | import java.util.Arrays; |
| 38 | import java.util.Comparator; |
| 39 | import java.util.List; |
| 40 | import java.util.Map; |
| 41 | import java.util.Set; |
| 42 | import java.util.regex.Pattern; |
| 43 | |
| 44 | /** |
| 45 | * A utility class for parsing App Compat Overrides flags. |
| 46 | * |
| 47 | * @hide |
| 48 | */ |
| 49 | final class AppCompatOverridesParser { |
| 50 | /** |
| 51 | * Flag for specifying all compat change IDs owned by a namespace. See {@link |
| 52 | * #parseOwnedChangeIds} for information on how this flag is parsed. |
| 53 | */ |
| 54 | static final String FLAG_OWNED_CHANGE_IDS = "owned_change_ids"; |
| 55 | |
| 56 | /** |
| 57 | * Flag for immediately removing overrides for certain packages and change IDs (from the compat |
| 58 | * platform), as well as stopping to apply them, in case of an emergency. See {@link |
| 59 | * #parseRemoveOverrides} for information on how this flag is parsed. |
| 60 | */ |
| 61 | static final String FLAG_REMOVE_OVERRIDES = "remove_overrides"; |
| 62 | |
| 63 | private static final String TAG = "AppCompatOverridesParser"; |
| 64 | |
| 65 | private static final String WILDCARD_SYMBOL = "*"; |
| 66 | |
| 67 | private static final Pattern BOOLEAN_PATTERN = |
| 68 | Pattern.compile("true|false", Pattern.CASE_INSENSITIVE); |
| 69 | |
| 70 | private static final String WILDCARD_NO_OWNED_CHANGE_IDS_WARNING = |
| 71 | "Wildcard can't be used in '" + FLAG_REMOVE_OVERRIDES + "' flag with an empty " |
| 72 | + FLAG_OWNED_CHANGE_IDS + "' flag"; |
| 73 | |
| 74 | private final PackageManager mPackageManager; |
| 75 | |
| 76 | AppCompatOverridesParser(PackageManager packageManager) { |
| 77 | mPackageManager = packageManager; |
| 78 | } |
| 79 | |
| 80 | /** |
| 81 | * Parses the given {@code configStr} and returns a map from package name to a set of change |
| 82 | * IDs to remove for that package. |
| 83 | * |
| 84 | * <p>The given {@code configStr} is expected to either be: |
| 85 | * |
| 86 | * <ul> |
| 87 | * <li>'*' (wildcard), to indicate that all owned overrides, specified in {@code |
| 88 | * ownedChangeIds}, for all installed packages should be removed. |
| 89 | * <li>A comma separated key value list, where the key is a package name and the value is |
| 90 | * either: |
| 91 | * <ul> |
| 92 | * <li>'*' (wildcard), to indicate that all owned overrides, specified in {@code |
| 93 | * ownedChangeIds} for that package should be removed. |
| 94 | * <li>A colon separated list of change IDs to remove for that package. |
| 95 | * </ul> |
| 96 | * </ul> |
| 97 | * |
| 98 | * <p>If the given {@code configStr} doesn't match the expected format, an empty map will be |
| 99 | * returned. If a specific change ID isn't a valid long, it will be ignored. |
| 100 | */ |
| 101 | Map<String, Set<Long>> parseRemoveOverrides(String configStr, Set<Long> ownedChangeIds) { |
| 102 | if (configStr.isEmpty()) { |
| 103 | return emptyMap(); |
| 104 | } |
| 105 | |
| 106 | Map<String, Set<Long>> result = new ArrayMap<>(); |
| 107 | if (configStr.equals(WILDCARD_SYMBOL)) { |
| 108 | if (ownedChangeIds.isEmpty()) { |
| 109 | Slog.w(TAG, WILDCARD_NO_OWNED_CHANGE_IDS_WARNING); |
| 110 | return emptyMap(); |
| 111 | } |
| 112 | List<ApplicationInfo> installedApps = mPackageManager.getInstalledApplications( |
| 113 | MATCH_ANY_USER); |
| 114 | for (ApplicationInfo appInfo : installedApps) { |
| 115 | result.put(appInfo.packageName, ownedChangeIds); |
| 116 | } |
| 117 | return result; |
| 118 | } |
| 119 | |
| 120 | KeyValueListParser parser = new KeyValueListParser(','); |
| 121 | try { |
| 122 | parser.setString(configStr); |
| 123 | } catch (IllegalArgumentException e) { |
| 124 | Slog.w( |
| 125 | TAG, |
| 126 | "Invalid format in '" + FLAG_REMOVE_OVERRIDES + "' flag: " + configStr, e); |
| 127 | return emptyMap(); |
| 128 | } |
| 129 | for (int i = 0; i < parser.size(); i++) { |
| 130 | String packageName = parser.keyAt(i); |
| 131 | String changeIdsStr = parser.getString(packageName, /* def= */ ""); |
| 132 | if (changeIdsStr.equals(WILDCARD_SYMBOL)) { |
| 133 | if (ownedChangeIds.isEmpty()) { |
| 134 | Slog.w(TAG, WILDCARD_NO_OWNED_CHANGE_IDS_WARNING); |
| 135 | continue; |
| 136 | } |
| 137 | result.put(packageName, ownedChangeIds); |
| 138 | } else { |
| 139 | for (String changeIdStr : changeIdsStr.split(":")) { |
| 140 | try { |
| 141 | long changeId = Long.parseLong(changeIdStr); |
| 142 | result.computeIfAbsent(packageName, k -> new ArraySet<>()).add(changeId); |
| 143 | } catch (NumberFormatException e) { |
| 144 | Slog.w( |
| 145 | TAG, |
| 146 | "Invalid change ID in '" + FLAG_REMOVE_OVERRIDES + "' flag: " |
| 147 | + changeIdStr, e); |
| 148 | } |
| 149 | } |
| 150 | } |
| 151 | } |
| 152 | |
| 153 | return result; |
| 154 | } |
| 155 | |
| 156 | |
| 157 | /** |
| 158 | * Parses the given {@code configStr}, that is expected to be a comma separated list of change |
| 159 | * IDs, into a set. |
| 160 | * |
| 161 | * <p>If any of the change IDs isn't a valid long, it will be ignored. |
| 162 | */ |
| 163 | static Set<Long> parseOwnedChangeIds(String configStr) { |
| 164 | if (configStr.isEmpty()) { |
| 165 | return emptySet(); |
| 166 | } |
| 167 | |
| 168 | Set<Long> result = new ArraySet<>(); |
| 169 | for (String changeIdStr : configStr.split(",")) { |
| 170 | try { |
| 171 | result.add(Long.parseLong(changeIdStr)); |
| 172 | } catch (NumberFormatException e) { |
| 173 | Slog.w(TAG, |
| 174 | "Invalid change ID in '" + FLAG_OWNED_CHANGE_IDS + "' flag: " + changeIdStr, |
| 175 | e); |
| 176 | } |
| 177 | } |
| 178 | return result; |
| 179 | } |
| 180 | |
| 181 | /** |
| 182 | * Parses the given {@code configStr}, that is expected to be a comma separated list of changes |
| 183 | * overrides, and returns a map from change ID to {@link PackageOverride} instances to add. |
| 184 | * |
| 185 | * <p>Each change override is in the following format: |
| 186 | * '<signature?>~<change-id>:<min-version-code?>:<max-version-code?>:<enabled>'. |
| 187 | * |
| 188 | * <p>The signature is optional, and will only be enforced if included. |
| 189 | * |
| 190 | * <p>If there are multiple overrides that should be added with the same change ID, the one |
| 191 | * that best fits the given {@code versionCode} is added. |
| 192 | * |
| 193 | * <p>Any overrides whose change ID is in {@code changeIdsToSkip} are ignored. |
| 194 | * |
| 195 | * <p>If a change override entry in {@code configStr} is invalid, it will be ignored. |
| 196 | */ |
| 197 | Map<Long, PackageOverride> parsePackageOverrides(String configStr, String packageName, |
| 198 | long versionCode, |
| 199 | Set<Long> changeIdsToSkip) { |
| 200 | if (configStr.isEmpty()) { |
| 201 | return emptyMap(); |
| 202 | } |
| 203 | PackageOverrideComparator comparator = new PackageOverrideComparator(versionCode); |
| 204 | Map<Long, PackageOverride> overridesToAdd = new ArrayMap<>(); |
| 205 | |
| 206 | Pair<String, String> signatureAndConfig = extractSignatureFromConfig(configStr); |
| 207 | if (signatureAndConfig == null) { |
| 208 | return emptyMap(); |
| 209 | } |
| 210 | final String signature = signatureAndConfig.first; |
| 211 | final String overridesConfig = signatureAndConfig.second; |
| 212 | |
| 213 | if (!verifySignature(packageName, signature)) { |
| 214 | return emptyMap(); |
| 215 | } |
| 216 | |
| 217 | for (String overrideEntryString : overridesConfig.split(",")) { |
| 218 | List<String> changeIdAndVersions = Arrays.asList(overrideEntryString.split(":", 4)); |
| 219 | if (changeIdAndVersions.size() != 4) { |
| 220 | Slog.w(TAG, "Invalid change override entry: " + overrideEntryString); |
| 221 | continue; |
| 222 | } |
| 223 | long changeId; |
| 224 | try { |
| 225 | changeId = Long.parseLong(changeIdAndVersions.get(0)); |
| 226 | } catch (NumberFormatException e) { |
| 227 | Slog.w(TAG, "Invalid change ID in override entry: " + overrideEntryString, e); |
| 228 | continue; |
| 229 | } |
| 230 | |
| 231 | if (changeIdsToSkip.contains(changeId)) { |
| 232 | continue; |
| 233 | } |
| 234 | |
| 235 | String minVersionCodeStr = changeIdAndVersions.get(1); |
| 236 | String maxVersionCodeStr = changeIdAndVersions.get(2); |
| 237 | |
| 238 | String enabledStr = changeIdAndVersions.get(3); |
| 239 | if (!BOOLEAN_PATTERN.matcher(enabledStr).matches()) { |
| 240 | Slog.w(TAG, "Invalid enabled string in override entry: " + overrideEntryString); |
| 241 | continue; |
| 242 | } |
| 243 | boolean enabled = Boolean.parseBoolean(enabledStr); |
| 244 | PackageOverride.Builder overrideBuilder = new PackageOverride.Builder().setEnabled( |
| 245 | enabled); |
| 246 | try { |
| 247 | if (!minVersionCodeStr.isEmpty()) { |
| 248 | overrideBuilder.setMinVersionCode(Long.parseLong(minVersionCodeStr)); |
| 249 | } |
| 250 | if (!maxVersionCodeStr.isEmpty()) { |
| 251 | overrideBuilder.setMaxVersionCode(Long.parseLong(maxVersionCodeStr)); |
| 252 | } |
| 253 | } catch (NumberFormatException e) { |
| 254 | Slog.w(TAG, |
| 255 | "Invalid min/max version code in override entry: " + overrideEntryString, |
| 256 | e); |
| 257 | continue; |
| 258 | } |
| 259 | |
| 260 | try { |
| 261 | PackageOverride override = overrideBuilder.build(); |
| 262 | if (!overridesToAdd.containsKey(changeId) |
| 263 | || comparator.compare(override, overridesToAdd.get(changeId)) < 0) { |
| 264 | overridesToAdd.put(changeId, override); |
| 265 | } |
| 266 | } catch (IllegalArgumentException e) { |
| 267 | Slog.w(TAG, "Failed to build PackageOverride", e); |
| 268 | } |
| 269 | } |
| 270 | |
| 271 | return overridesToAdd; |
| 272 | } |
| 273 | |
| 274 | /** |
| 275 | * Extracts the signature from the config string if one exists. |
| 276 | * |
| 277 | * @param configStr String in the form of <signature?>~<overrideConfig> |
| 278 | */ |
| 279 | @Nullable |
| 280 | private static Pair<String, String> extractSignatureFromConfig(String configStr) { |
| 281 | final List<String> signatureAndConfig = Arrays.asList(configStr.split("~")); |
| 282 | |
| 283 | if (signatureAndConfig.size() == 1) { |
| 284 | // The config string doesn't contain a signature. |
| 285 | return Pair.create("", configStr); |
| 286 | } |
| 287 | |
| 288 | if (signatureAndConfig.size() > 2) { |
| 289 | Slog.w(TAG, "Only one signature per config is supported. Config: " + configStr); |
| 290 | return null; |
| 291 | } |
| 292 | |
| 293 | return Pair.create(signatureAndConfig.get(0), signatureAndConfig.get(1)); |
| 294 | } |
| 295 | |
| 296 | /** |
| 297 | * Verifies that the specified package was signed with a particular signature. |
| 298 | * |
| 299 | * @param packageName The package to check. |
| 300 | * @param signature The optional signature to verify. If empty, we return true. |
| 301 | * @return Whether the package is signed with that signature. |
| 302 | */ |
| 303 | private boolean verifySignature(String packageName, String signature) { |
| 304 | try { |
| 305 | final boolean signatureValid = signature.isEmpty() |
| 306 | || mPackageManager.hasSigningCertificate(packageName, |
| 307 | HexEncoding.decode(signature), CERT_INPUT_SHA256); |
| 308 | |
| 309 | if (!signatureValid) { |
| 310 | Slog.w(TAG, packageName + " did not have expected signature: " + signature); |
| 311 | } |
| 312 | return signatureValid; |
| 313 | } catch (IllegalArgumentException e) { |
| 314 | Slog.w(TAG, "Unable to verify signature " + signature + " for " + packageName, e); |
| 315 | return false; |
| 316 | } |
| 317 | } |
| 318 | |
| 319 | /** |
| 320 | * A {@link Comparator} that compares @link PackageOverride} instances with respect to a |
| 321 | * specified {@code versionCode} as follows: |
| 322 | * |
| 323 | * <ul> |
| 324 | * <li>Prefer the {@link PackageOverride} whose version range contains {@code versionCode}. |
| 325 | * <li>Otherwise, prefer the {@link PackageOverride} whose version range is closest to {@code |
| 326 | * versionCode} from below. |
| 327 | * <li>Otherwise, prefer the {@link PackageOverride} whose version range is closest to {@code |
| 328 | * versionCode} from above. |
| 329 | * </ul> |
| 330 | */ |
| 331 | private static final class PackageOverrideComparator implements Comparator<PackageOverride> { |
| 332 | private final long mVersionCode; |
| 333 | |
| 334 | PackageOverrideComparator(long versionCode) { |
| 335 | this.mVersionCode = versionCode; |
| 336 | } |
| 337 | |
| 338 | @Override |
| 339 | public int compare(PackageOverride o1, PackageOverride o2) { |
| 340 | // Prefer overrides whose version range contains versionCode. |
| 341 | boolean isVersionInRange1 = isVersionInRange(o1, mVersionCode); |
| 342 | boolean isVersionInRange2 = isVersionInRange(o2, mVersionCode); |
| 343 | if (isVersionInRange1 != isVersionInRange2) { |
| 344 | return isVersionInRange1 ? -1 : 1; |
| 345 | } |
| 346 | |
| 347 | // Otherwise, prefer overrides whose version range is before versionCode. |
| 348 | boolean isVersionAfterRange1 = isVersionAfterRange(o1, mVersionCode); |
| 349 | boolean isVersionAfterRange2 = isVersionAfterRange(o2, mVersionCode); |
| 350 | if (isVersionAfterRange1 != isVersionAfterRange2) { |
| 351 | return isVersionAfterRange1 ? -1 : 1; |
| 352 | } |
| 353 | |
| 354 | // If both overrides' version ranges are either before or after versionCode, prefer |
| 355 | // those whose version range is closer to versionCode. |
| 356 | return Long.compare( |
| 357 | getVersionProximity(o1, mVersionCode), getVersionProximity(o2, mVersionCode)); |
| 358 | } |
| 359 | |
| 360 | /** |
| 361 | * Returns true if the version range in the given {@code override} contains {@code |
| 362 | * versionCode}. |
| 363 | */ |
| 364 | private static boolean isVersionInRange(PackageOverride override, long versionCode) { |
| 365 | return override.getMinVersionCode() <= versionCode |
| 366 | && versionCode <= override.getMaxVersionCode(); |
| 367 | } |
| 368 | |
| 369 | /** |
| 370 | * Returns true if the given {@code versionCode} is strictly after the version range in the |
| 371 | * given {@code override}. |
| 372 | */ |
| 373 | private static boolean isVersionAfterRange(PackageOverride override, long versionCode) { |
| 374 | return override.getMaxVersionCode() < versionCode; |
| 375 | } |
| 376 | |
| 377 | /** |
| 378 | * Returns true if the given {@code versionCode} is strictly before the version range in the |
| 379 | * given {@code override}. |
| 380 | */ |
| 381 | private static boolean isVersionBeforeRange(PackageOverride override, long versionCode) { |
| 382 | return override.getMinVersionCode() > versionCode; |
| 383 | } |
| 384 | |
| 385 | /** |
| 386 | * In case the given {@code versionCode} is strictly before or after the version range in |
| 387 | * the given {@code override}, returns the distance from it, otherwise returns zero. |
| 388 | */ |
| 389 | private static long getVersionProximity(PackageOverride override, long versionCode) { |
| 390 | if (isVersionAfterRange(override, versionCode)) { |
| 391 | return versionCode - override.getMaxVersionCode(); |
| 392 | } |
| 393 | if (isVersionBeforeRange(override, versionCode)) { |
| 394 | return override.getMinVersionCode() - versionCode; |
| 395 | } |
| 396 | |
| 397 | // Version is in range. Note that when two overrides have a zero version proximity |
| 398 | // they will be ordered arbitrarily. |
| 399 | return 0; |
| 400 | } |
| 401 | } |
| 402 | } |