David Zeuthen | 8b6973b | 2016-09-20 12:39:49 -0400 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright (C) 2016 The Android Open Source Project |
| 3 | * |
| 4 | * Permission is hereby granted, free of charge, to any person |
| 5 | * obtaining a copy of this software and associated documentation |
| 6 | * files (the "Software"), to deal in the Software without |
| 7 | * restriction, including without limitation the rights to use, copy, |
| 8 | * modify, merge, publish, distribute, sublicense, and/or sell copies |
| 9 | * of the Software, and to permit persons to whom the Software is |
| 10 | * furnished to do so, subject to the following conditions: |
| 11 | * |
| 12 | * The above copyright notice and this permission notice shall be |
| 13 | * included in all copies or substantial portions of the Software. |
| 14 | * |
| 15 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, |
| 16 | * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF |
| 17 | * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND |
| 18 | * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS |
| 19 | * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN |
| 20 | * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN |
| 21 | * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE |
| 22 | * SOFTWARE. |
| 23 | */ |
| 24 | |
| 25 | #include "avb_ab_flow.h" |
| 26 | #include "avb_util.h" |
| 27 | |
| 28 | bool avb_ab_data_verify_and_byteswap(const AvbABData* src, AvbABData* dest) { |
| 29 | /* Ensure magic is correct. */ |
| 30 | if (avb_safe_memcmp(src->magic, AVB_AB_MAGIC, AVB_AB_MAGIC_LEN) != 0) { |
| 31 | avb_error("Magic is incorrect.\n"); |
| 32 | return false; |
| 33 | } |
| 34 | |
| 35 | avb_memcpy(dest, src, sizeof(AvbABData)); |
| 36 | dest->crc32 = avb_be32toh(dest->crc32); |
| 37 | |
| 38 | /* Ensure we don't attempt to access any fields if the major version |
| 39 | * is not supported. |
| 40 | */ |
| 41 | if (dest->version_major > AVB_AB_MAJOR_VERSION) { |
| 42 | avb_error("No support for given major version.\n"); |
| 43 | return false; |
| 44 | } |
| 45 | |
| 46 | /* Bail if CRC32 doesn't match. */ |
| 47 | if (dest->crc32 != |
| 48 | avb_crc32((const uint8_t*)dest, sizeof(AvbABData) - sizeof(uint32_t))) { |
| 49 | avb_error("CRC32 does not match.\n"); |
| 50 | return false; |
| 51 | } |
| 52 | |
| 53 | return true; |
| 54 | } |
| 55 | |
| 56 | void avb_ab_data_update_crc_and_byteswap(const AvbABData* src, |
| 57 | AvbABData* dest) { |
| 58 | avb_memcpy(dest, src, sizeof(AvbABData)); |
| 59 | dest->crc32 = avb_htobe32( |
| 60 | avb_crc32((const uint8_t*)dest, sizeof(AvbABData) - sizeof(uint32_t))); |
| 61 | } |
| 62 | |
| 63 | void avb_ab_data_init(AvbABData* data) { |
| 64 | avb_memset(data, '\0', sizeof(AvbABData)); |
| 65 | avb_memcpy(data->magic, AVB_AB_MAGIC, AVB_AB_MAGIC_LEN); |
| 66 | data->version_major = AVB_AB_MAJOR_VERSION; |
| 67 | data->version_minor = AVB_AB_MINOR_VERSION; |
| 68 | data->slots[0].priority = AVB_AB_MAX_PRIORITY; |
| 69 | data->slots[0].tries_remaining = AVB_AB_MAX_TRIES_REMAINING; |
| 70 | data->slots[0].successful_boot = 0; |
| 71 | data->slots[1].priority = AVB_AB_MAX_PRIORITY - 1; |
| 72 | data->slots[1].tries_remaining = AVB_AB_MAX_TRIES_REMAINING; |
| 73 | data->slots[1].successful_boot = 0; |
| 74 | } |
| 75 | |
| 76 | /* The AvbABData struct is stored 2048 bytes into the 'misc' partition |
| 77 | * following the 'struct bootloader_message' field. The struct is |
| 78 | * compatible with the guidelines in bootable/recovery/bootloader.h - |
| 79 | * e.g. it is stored in the |slot_suffix| field, starts with a |
| 80 | * NUL-byte, and is 32 bytes long. |
| 81 | */ |
| 82 | #define AB_METADATA_MISC_PARTITION_OFFSET 2048 |
| 83 | |
| 84 | bool avb_ab_data_read(AvbOps* ops, AvbABData* data) { |
| 85 | AvbABData serialized; |
| 86 | AvbIOResult io_result; |
| 87 | size_t num_bytes_read; |
| 88 | |
| 89 | io_result = |
| 90 | ops->read_from_partition(ops, "misc", AB_METADATA_MISC_PARTITION_OFFSET, |
| 91 | sizeof(AvbABData), &serialized, &num_bytes_read); |
| 92 | if (io_result != AVB_IO_RESULT_OK || num_bytes_read != sizeof(AvbABData)) { |
| 93 | avb_error("Error reading A/B metadata.\n"); |
| 94 | return false; |
| 95 | } |
| 96 | |
| 97 | if (!avb_ab_data_verify_and_byteswap(&serialized, data)) { |
| 98 | avb_error( |
| 99 | "Error validating A/B metadata from disk. " |
| 100 | "Resetting and writing new A/B metadata to disk.\n"); |
| 101 | avb_ab_data_init(data); |
| 102 | return avb_ab_data_write(ops, data); |
| 103 | } |
| 104 | |
| 105 | return true; |
| 106 | } |
| 107 | |
| 108 | bool avb_ab_data_write(AvbOps* ops, const AvbABData* data) { |
| 109 | AvbABData serialized; |
| 110 | AvbIOResult io_result; |
| 111 | |
| 112 | avb_ab_data_update_crc_and_byteswap(data, &serialized); |
| 113 | io_result = |
| 114 | ops->write_to_partition(ops, "misc", AB_METADATA_MISC_PARTITION_OFFSET, |
| 115 | sizeof(AvbABData), &serialized); |
| 116 | if (io_result != AVB_IO_RESULT_OK) { |
| 117 | avb_error("Error writing A/B metadata.\n"); |
| 118 | return false; |
| 119 | } |
| 120 | return true; |
| 121 | } |
| 122 | |
| 123 | static bool slot_is_bootable(AvbABSlotData* slot) { |
| 124 | return slot->priority > 0 && |
| 125 | (slot->successful_boot || (slot->tries_remaining > 0)); |
| 126 | } |
| 127 | |
| 128 | static void slot_set_unbootable(AvbABSlotData* slot) { |
| 129 | slot->priority = 0; |
| 130 | slot->tries_remaining = 0; |
| 131 | slot->successful_boot = 0; |
| 132 | } |
| 133 | |
| 134 | /* Ensure all unbootable and/or illegal states are marked as the |
| 135 | * canonical 'unbootable' state, e.g. priority=0, tries_remaining=0, |
| 136 | * and successful_boot=0. |
| 137 | */ |
| 138 | static void slot_normalize(AvbABSlotData* slot) { |
| 139 | if (slot->priority > 0) { |
| 140 | if (slot->tries_remaining == 0 && !slot->successful_boot) { |
| 141 | /* We've exhausted all tries -> unbootable. */ |
| 142 | slot_set_unbootable(slot); |
| 143 | } |
| 144 | if (slot->tries_remaining > 0 && slot->successful_boot) { |
| 145 | /* Illegal state - avb_ab_mark_slot_successful() will clear |
| 146 | * tries_remaining when setting successful_boot. |
| 147 | */ |
| 148 | slot_set_unbootable(slot); |
| 149 | } |
| 150 | } else { |
| 151 | slot_set_unbootable(slot); |
| 152 | } |
| 153 | } |
| 154 | |
| 155 | static const char* slot_suffixes[2] = {"_a", "_b"}; |
| 156 | |
| 157 | /* Helper function to metadata - returns false if an I/O error occurs. */ |
| 158 | static bool load_metadata(AvbOps* ops, AvbABData* ab_data, |
| 159 | AvbABData* ab_data_orig) { |
| 160 | if (!avb_ab_data_read(ops, ab_data)) { |
| 161 | avb_error("I/O error while loading A/B metadata.\n"); |
| 162 | return false; |
| 163 | } |
| 164 | *ab_data_orig = *ab_data; |
| 165 | |
| 166 | /* Ensure data is normalized, e.g. illegal states will be marked as |
| 167 | * unbootable and all unbootable states are represented with |
| 168 | * (priority=0, tries_remaining=0, successful_boot=0). |
| 169 | */ |
| 170 | slot_normalize(&ab_data->slots[0]); |
| 171 | slot_normalize(&ab_data->slots[1]); |
| 172 | return true; |
| 173 | } |
| 174 | |
| 175 | /* Writes A/B metadata to disk only if it has changed - returns false |
| 176 | * if an I/O error occurs. |
| 177 | */ |
| 178 | static bool save_metadata_if_changed(AvbOps* ops, AvbABData* ab_data, |
| 179 | AvbABData* ab_data_orig) { |
| 180 | if (avb_safe_memcmp(ab_data, ab_data_orig, sizeof(AvbABData)) != 0) { |
| 181 | avb_debug("Writing A/B metadata to disk.\n"); |
| 182 | if (!avb_ab_data_write(ops, ab_data)) { |
| 183 | avb_error("Error writing A/B metadata to disk.\n"); |
| 184 | return false; |
| 185 | } |
| 186 | } |
| 187 | return true; |
| 188 | } |
| 189 | |
| 190 | AvbABFlowResult avb_ab_flow(AvbOps* ops, AvbSlotVerifyData** out_data) { |
| 191 | AvbSlotVerifyData* slot_data[2] = {NULL, NULL}; |
| 192 | AvbSlotVerifyData* data = NULL; |
| 193 | AvbABFlowResult ret; |
| 194 | AvbABData ab_data, ab_data_orig; |
| 195 | size_t slot_index_to_boot, n; |
| 196 | |
| 197 | if (!load_metadata(ops, &ab_data, &ab_data_orig)) { |
| 198 | ret = AVB_AB_FLOW_RESULT_ERROR_IO; |
| 199 | goto out; |
| 200 | } |
| 201 | |
| 202 | /* Validate all bootable slots. */ |
| 203 | for (n = 0; n < 2; n++) { |
| 204 | if (slot_is_bootable(&ab_data.slots[n])) { |
| 205 | AvbSlotVerifyResult verify_result; |
| 206 | verify_result = avb_slot_verify(ops, slot_suffixes[n], &slot_data[n]); |
| 207 | if (verify_result != AVB_SLOT_VERIFY_RESULT_OK) { |
| 208 | if (verify_result == AVB_AB_FLOW_RESULT_ERROR_OOM) { |
| 209 | ret = AVB_AB_FLOW_RESULT_ERROR_OOM; |
| 210 | goto out; |
| 211 | } |
| 212 | if (verify_result == AVB_AB_FLOW_RESULT_ERROR_IO) { |
| 213 | ret = AVB_AB_FLOW_RESULT_ERROR_IO; |
| 214 | goto out; |
| 215 | } |
| 216 | avb_errorv("Error verifying slot ", slot_suffixes[n], " with result ", |
| 217 | avb_slot_verify_result_to_string(verify_result), |
| 218 | " - setting unbootable.\n", NULL); |
| 219 | slot_set_unbootable(&ab_data.slots[n]); |
| 220 | } |
| 221 | } |
| 222 | } |
| 223 | |
| 224 | if (slot_is_bootable(&ab_data.slots[0]) && |
| 225 | slot_is_bootable(&ab_data.slots[1])) { |
| 226 | if (ab_data.slots[1].priority > ab_data.slots[0].priority) { |
| 227 | slot_index_to_boot = 1; |
| 228 | } else { |
| 229 | slot_index_to_boot = 0; |
| 230 | } |
| 231 | } else if (slot_is_bootable(&ab_data.slots[0])) { |
| 232 | slot_index_to_boot = 0; |
| 233 | } else if (slot_is_bootable(&ab_data.slots[1])) { |
| 234 | slot_index_to_boot = 1; |
| 235 | } else { |
| 236 | /* No bootable slots! */ |
| 237 | avb_error("No bootable slots found.\n"); |
| 238 | ret = AVB_AB_FLOW_RESULT_ERROR_NO_BOOTABLE_SLOTS; |
| 239 | goto out; |
| 240 | } |
| 241 | |
| 242 | /* Update stored rollback index such that the stored rollback index |
| 243 | * is the largest value supporting all currently bootable slots. Do |
| 244 | * this for every rollback index slot. |
| 245 | */ |
| 246 | for (n = 0; n < AVB_MAX_NUMBER_OF_ROLLBACK_INDEX_SLOTS; n++) { |
| 247 | uint64_t rollback_index_value = 0; |
| 248 | |
| 249 | if (slot_data[0] != NULL && slot_data[1] != NULL) { |
| 250 | uint64_t a_rollback_index = slot_data[0]->rollback_indexes[n]; |
| 251 | uint64_t b_rollback_index = slot_data[1]->rollback_indexes[n]; |
| 252 | rollback_index_value = |
| 253 | (a_rollback_index < b_rollback_index ? a_rollback_index |
| 254 | : b_rollback_index); |
| 255 | } else if (slot_data[0] != NULL) { |
| 256 | rollback_index_value = slot_data[0]->rollback_indexes[n]; |
| 257 | } else if (slot_data[1] != NULL) { |
| 258 | rollback_index_value = slot_data[1]->rollback_indexes[n]; |
| 259 | } |
| 260 | |
| 261 | if (rollback_index_value != 0) { |
| 262 | uint64_t current_rollback_index_value; |
| 263 | if (!ops->read_rollback_index(ops, n, ¤t_rollback_index_value)) { |
| 264 | avb_error("Error getting rollback index for slot.\n"); |
| 265 | ret = AVB_AB_FLOW_RESULT_ERROR_IO; |
| 266 | goto out; |
| 267 | } |
| 268 | if (current_rollback_index_value != rollback_index_value) { |
| 269 | if (!ops->write_rollback_index(ops, n, rollback_index_value)) { |
| 270 | avb_error("Error setting stored rollback index.\n"); |
| 271 | ret = AVB_AB_FLOW_RESULT_ERROR_IO; |
| 272 | goto out; |
| 273 | } |
| 274 | } |
| 275 | } |
| 276 | } |
| 277 | |
| 278 | /* Finally, select this slot. */ |
| 279 | avb_assert(slot_data[slot_index_to_boot] != NULL); |
| 280 | data = slot_data[slot_index_to_boot]; |
| 281 | slot_data[slot_index_to_boot] = NULL; |
| 282 | ret = AVB_AB_FLOW_RESULT_OK; |
| 283 | |
| 284 | /* ... and decrement tries remaining, if applicable. */ |
| 285 | if (!ab_data.slots[slot_index_to_boot].successful_boot && |
| 286 | ab_data.slots[slot_index_to_boot].tries_remaining > 0) { |
| 287 | ab_data.slots[slot_index_to_boot].tries_remaining -= 1; |
| 288 | } |
| 289 | |
| 290 | out: |
| 291 | if (!save_metadata_if_changed(ops, &ab_data, &ab_data_orig)) { |
| 292 | ret = AVB_AB_FLOW_RESULT_ERROR_IO; |
| 293 | if (data != NULL) { |
| 294 | avb_slot_verify_data_free(data); |
| 295 | data = NULL; |
| 296 | } |
| 297 | } |
| 298 | |
| 299 | for (n = 0; n < 2; n++) { |
| 300 | if (slot_data[n] != NULL) { |
| 301 | avb_slot_verify_data_free(slot_data[n]); |
| 302 | } |
| 303 | } |
| 304 | |
| 305 | if (out_data != NULL) { |
| 306 | *out_data = data; |
| 307 | } else { |
| 308 | if (data != NULL) { |
| 309 | avb_slot_verify_data_free(data); |
| 310 | } |
| 311 | } |
| 312 | |
| 313 | return ret; |
| 314 | } |
| 315 | |
| 316 | bool avb_ab_mark_slot_active(AvbOps* ops, unsigned int slot_number) { |
| 317 | AvbABData ab_data, ab_data_orig; |
| 318 | bool ret = false; |
| 319 | unsigned int other_slot_number; |
| 320 | |
| 321 | avb_assert(slot_number < 2); |
| 322 | |
| 323 | if (!load_metadata(ops, &ab_data, &ab_data_orig)) { |
| 324 | goto out; |
| 325 | } |
| 326 | |
| 327 | /* Make requested slot top priority, unsuccessful, and with max tries. */ |
| 328 | ab_data.slots[slot_number].priority = AVB_AB_MAX_PRIORITY; |
| 329 | ab_data.slots[slot_number].tries_remaining = AVB_AB_MAX_TRIES_REMAINING; |
| 330 | ab_data.slots[slot_number].successful_boot = 0; |
| 331 | |
| 332 | /* Ensure other slot doesn't have as high a priority. */ |
| 333 | other_slot_number = 1 - slot_number; |
| 334 | if (ab_data.slots[other_slot_number].priority == AVB_AB_MAX_PRIORITY) { |
| 335 | ab_data.slots[other_slot_number].priority = AVB_AB_MAX_PRIORITY - 1; |
| 336 | } |
| 337 | |
| 338 | ret = true; |
| 339 | |
| 340 | out: |
| 341 | if (!save_metadata_if_changed(ops, &ab_data, &ab_data_orig)) { |
| 342 | ret = false; |
| 343 | } |
| 344 | return ret; |
| 345 | } |
| 346 | |
| 347 | bool avb_ab_mark_slot_unbootable(AvbOps* ops, unsigned int slot_number) { |
| 348 | AvbABData ab_data, ab_data_orig; |
| 349 | bool ret = false; |
| 350 | |
| 351 | avb_assert(slot_number < 2); |
| 352 | |
| 353 | if (!load_metadata(ops, &ab_data, &ab_data_orig)) { |
| 354 | goto out; |
| 355 | } |
| 356 | |
| 357 | slot_set_unbootable(&ab_data.slots[slot_number]); |
| 358 | ret = true; |
| 359 | |
| 360 | out: |
| 361 | if (!save_metadata_if_changed(ops, &ab_data, &ab_data_orig)) { |
| 362 | ret = false; |
| 363 | } |
| 364 | return ret; |
| 365 | } |
| 366 | |
| 367 | bool avb_ab_mark_slot_successful(AvbOps* ops, unsigned int slot_number) { |
| 368 | AvbABData ab_data, ab_data_orig; |
| 369 | bool ret = false; |
| 370 | |
| 371 | avb_assert(slot_number < 2); |
| 372 | |
| 373 | if (!load_metadata(ops, &ab_data, &ab_data_orig)) { |
| 374 | goto out; |
| 375 | } |
| 376 | |
| 377 | if (!slot_is_bootable(&ab_data.slots[slot_number])) { |
| 378 | avb_error("Cannot mark unbootable slot as successful.\n"); |
| 379 | goto out; |
| 380 | } |
| 381 | |
| 382 | ab_data.slots[slot_number].tries_remaining = 0; |
| 383 | ab_data.slots[slot_number].successful_boot = 1; |
| 384 | |
| 385 | ret = true; |
| 386 | |
| 387 | out: |
| 388 | if (!save_metadata_if_changed(ops, &ab_data, &ab_data_orig)) { |
| 389 | ret = false; |
| 390 | } |
| 391 | return ret; |
| 392 | } |