diff options
Diffstat (limited to 'lib/avb/libavb_ab')
| -rw-r--r-- | lib/avb/libavb_ab/Makefile | 2 | ||||
| -rw-r--r-- | lib/avb/libavb_ab/avb_ab_flow.c | 516 | ||||
| -rw-r--r-- | lib/avb/libavb_ab/avb_ab_flow.h | 253 | ||||
| -rw-r--r-- | lib/avb/libavb_ab/avb_ab_ops.h | 79 | ||||
| -rw-r--r-- | lib/avb/libavb_ab/libavb_ab.h | 40 |
5 files changed, 890 insertions, 0 deletions
diff --git a/lib/avb/libavb_ab/Makefile b/lib/avb/libavb_ab/Makefile new file mode 100644 index 0000000..f22d0ed --- /dev/null +++ b/lib/avb/libavb_ab/Makefile @@ -0,0 +1,2 @@ +ccflags-y += -DAVB_COMPILATION +obj-y += avb_ab_flow.o diff --git a/lib/avb/libavb_ab/avb_ab_flow.c b/lib/avb/libavb_ab/avb_ab_flow.c new file mode 100644 index 0000000..3adb927 --- /dev/null +++ b/lib/avb/libavb_ab/avb_ab_flow.c @@ -0,0 +1,516 @@ +/* + * Copyright (C) 2016 The Android Open Source Project + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, copy, + * modify, merge, publish, distribute, sublicense, and/or sell copies + * of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#include "avb_ab_flow.h" + +bool avb_ab_data_verify_and_byteswap(const AvbABData* src, AvbABData* dest) { + /* Ensure magic is correct. */ + if (avb_safe_memcmp(src->magic, AVB_AB_MAGIC, AVB_AB_MAGIC_LEN) != 0) { + avb_error("Magic is incorrect.\n"); + return false; + } + + avb_memcpy(dest, src, sizeof(AvbABData)); + dest->crc32 = avb_be32toh(dest->crc32); + + /* Ensure we don't attempt to access any fields if the major version + * is not supported. + */ + if (dest->version_major > AVB_AB_MAJOR_VERSION) { + avb_error("No support for given major version.\n"); + return false; + } + + /* Bail if CRC32 doesn't match. */ + if (dest->crc32 != + avb_crc32((const uint8_t*)dest, sizeof(AvbABData) - sizeof(uint32_t))) { + avb_error("CRC32 does not match.\n"); + return false; + } + + return true; +} + +void avb_ab_data_update_crc_and_byteswap(const AvbABData* src, + AvbABData* dest) { + avb_memcpy(dest, src, sizeof(AvbABData)); + dest->crc32 = avb_htobe32( + avb_crc32((const uint8_t*)dest, sizeof(AvbABData) - sizeof(uint32_t))); +} + +void avb_ab_data_init(AvbABData* data) { + avb_memset(data, '\0', sizeof(AvbABData)); + avb_memcpy(data->magic, AVB_AB_MAGIC, AVB_AB_MAGIC_LEN); + data->version_major = AVB_AB_MAJOR_VERSION; + data->version_minor = AVB_AB_MINOR_VERSION; + data->slots[0].priority = AVB_AB_MAX_PRIORITY; + data->slots[0].tries_remaining = AVB_AB_MAX_TRIES_REMAINING; + data->slots[0].successful_boot = 0; + data->slots[1].priority = AVB_AB_MAX_PRIORITY - 1; + data->slots[1].tries_remaining = AVB_AB_MAX_TRIES_REMAINING; + data->slots[1].successful_boot = 0; +} + +/* The AvbABData struct is stored 2048 bytes into the 'misc' partition + * following the 'struct bootloader_message' field. The struct is + * compatible with the guidelines in bootable/recovery/bootloader.h - + * e.g. it is stored in the |slot_suffix| field, starts with a + * NUL-byte, and is 32 bytes long. + */ +#define AB_METADATA_MISC_PARTITION_OFFSET 2048 + +AvbIOResult avb_ab_data_read(AvbABOps* ab_ops, AvbABData* data) { + AvbOps* ops = ab_ops->ops; + AvbABData serialized; + AvbIOResult io_ret; + size_t num_bytes_read; + + io_ret = ops->read_from_partition(ops, + "misc", + AB_METADATA_MISC_PARTITION_OFFSET, + sizeof(AvbABData), + &serialized, + &num_bytes_read); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + return AVB_IO_RESULT_ERROR_OOM; + } else if (io_ret != AVB_IO_RESULT_OK || + num_bytes_read != sizeof(AvbABData)) { + avb_error("Error reading A/B metadata.\n"); + return AVB_IO_RESULT_ERROR_IO; + } + + if (!avb_ab_data_verify_and_byteswap(&serialized, data)) { + avb_error( + "Error validating A/B metadata from disk. " + "Resetting and writing new A/B metadata to disk.\n"); + avb_ab_data_init(data); + return avb_ab_data_write(ab_ops, data); + } + + return AVB_IO_RESULT_OK; +} + +AvbIOResult avb_ab_data_write(AvbABOps* ab_ops, const AvbABData* data) { + AvbOps* ops = ab_ops->ops; + AvbABData serialized; + AvbIOResult io_ret; + + avb_ab_data_update_crc_and_byteswap(data, &serialized); + io_ret = ops->write_to_partition(ops, + "misc", + AB_METADATA_MISC_PARTITION_OFFSET, + sizeof(AvbABData), + &serialized); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + return AVB_IO_RESULT_ERROR_OOM; + } else if (io_ret != AVB_IO_RESULT_OK) { + avb_error("Error writing A/B metadata.\n"); + return AVB_IO_RESULT_ERROR_IO; + } + return AVB_IO_RESULT_OK; +} + +static bool slot_is_bootable(AvbABSlotData* slot) { + return slot->priority > 0 && + (slot->successful_boot || (slot->tries_remaining > 0)); +} + +static void slot_set_unbootable(AvbABSlotData* slot) { + slot->priority = 0; + slot->tries_remaining = 0; + slot->successful_boot = 0; +} + +/* Ensure all unbootable and/or illegal states are marked as the + * canonical 'unbootable' state, e.g. priority=0, tries_remaining=0, + * and successful_boot=0. + */ +static void slot_normalize(AvbABSlotData* slot) { + if (slot->priority > 0) { + if (slot->tries_remaining == 0 && !slot->successful_boot) { + /* We've exhausted all tries -> unbootable. */ + slot_set_unbootable(slot); + } + if (slot->tries_remaining > 0 && slot->successful_boot) { + /* Illegal state - avb_ab_mark_slot_successful() will clear + * tries_remaining when setting successful_boot. + */ + slot_set_unbootable(slot); + } + } else { + slot_set_unbootable(slot); + } +} + +static const char* slot_suffixes[2] = {"_a", "_b"}; + +/* Helper function to load metadata - returns AVB_IO_RESULT_OK on + * success, error code otherwise. + */ +static AvbIOResult load_metadata(AvbABOps* ab_ops, + AvbABData* ab_data, + AvbABData* ab_data_orig) { + AvbIOResult io_ret; + + io_ret = ab_ops->read_ab_metadata(ab_ops, ab_data); + if (io_ret != AVB_IO_RESULT_OK) { + avb_error("I/O error while loading A/B metadata.\n"); + return io_ret; + } + *ab_data_orig = *ab_data; + + /* Ensure data is normalized, e.g. illegal states will be marked as + * unbootable and all unbootable states are represented with + * (priority=0, tries_remaining=0, successful_boot=0). + */ + slot_normalize(&ab_data->slots[0]); + slot_normalize(&ab_data->slots[1]); + return AVB_IO_RESULT_OK; +} + +/* Writes A/B metadata to disk only if it has changed - returns + * AVB_IO_RESULT_OK on success, error code otherwise. + */ +static AvbIOResult save_metadata_if_changed(AvbABOps* ab_ops, + AvbABData* ab_data, + AvbABData* ab_data_orig) { + if (avb_safe_memcmp(ab_data, ab_data_orig, sizeof(AvbABData)) != 0) { + avb_debug("Writing A/B metadata to disk.\n"); + return ab_ops->write_ab_metadata(ab_ops, ab_data); + } + return AVB_IO_RESULT_OK; +} + +AvbABFlowResult avb_ab_flow(AvbABOps* ab_ops, + const char* const* requested_partitions, + bool allow_verification_error, + AvbSlotVerifyData** out_data) { + AvbOps* ops = ab_ops->ops; + AvbSlotVerifyData* slot_data[2] = {NULL, NULL}; + AvbSlotVerifyData* data = NULL; + AvbABFlowResult ret; + AvbABData ab_data, ab_data_orig; + size_t slot_index_to_boot, n; + AvbIOResult io_ret; + bool saw_and_allowed_verification_error = false; + + io_ret = load_metadata(ab_ops, &ab_data, &ab_data_orig); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + ret = AVB_AB_FLOW_RESULT_ERROR_OOM; + goto out; + } else if (io_ret != AVB_IO_RESULT_OK) { + ret = AVB_AB_FLOW_RESULT_ERROR_IO; + goto out; + } + + /* Validate all bootable slots. */ + for (n = 0; n < 2; n++) { + if (slot_is_bootable(&ab_data.slots[n])) { + AvbSlotVerifyResult verify_result; + bool set_slot_unbootable = false; + + verify_result = avb_slot_verify(ops, + requested_partitions, + slot_suffixes[n], + allow_verification_error, + &slot_data[n]); + switch (verify_result) { + case AVB_SLOT_VERIFY_RESULT_ERROR_OOM: + ret = AVB_AB_FLOW_RESULT_ERROR_OOM; + goto out; + + case AVB_SLOT_VERIFY_RESULT_ERROR_IO: + ret = AVB_AB_FLOW_RESULT_ERROR_IO; + goto out; + + case AVB_SLOT_VERIFY_RESULT_OK: + break; + + case AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA: + case AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION: + /* Even with |allow_verification_error| these mean game over. */ + set_slot_unbootable = true; + break; + + /* explicit fallthrough. */ + case AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION: + case AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX: + case AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED: + if (allow_verification_error) { + /* Do nothing since we allow this. */ + avb_debugv("Allowing slot ", + slot_suffixes[n], + " which verified " + "with result ", + avb_slot_verify_result_to_string(verify_result), + " because |allow_verification_error| is true.\n", + NULL); + saw_and_allowed_verification_error = true; + } else { + set_slot_unbootable = true; + } + break; + } + + if (set_slot_unbootable) { + avb_errorv("Error verifying slot ", + slot_suffixes[n], + " with result ", + avb_slot_verify_result_to_string(verify_result), + " - setting unbootable.\n", + NULL); + slot_set_unbootable(&ab_data.slots[n]); + } + } + } + + if (slot_is_bootable(&ab_data.slots[0]) && + slot_is_bootable(&ab_data.slots[1])) { + if (ab_data.slots[1].priority > ab_data.slots[0].priority) { + slot_index_to_boot = 1; + } else { + slot_index_to_boot = 0; + } + } else if (slot_is_bootable(&ab_data.slots[0])) { + slot_index_to_boot = 0; + } else if (slot_is_bootable(&ab_data.slots[1])) { + slot_index_to_boot = 1; + } else { + /* No bootable slots! */ + avb_error("No bootable slots found.\n"); + ret = AVB_AB_FLOW_RESULT_ERROR_NO_BOOTABLE_SLOTS; + goto out; + } + + /* Update stored rollback index such that the stored rollback index + * is the largest value supporting all currently bootable slots. Do + * this for every rollback index location. + */ + for (n = 0; n < AVB_MAX_NUMBER_OF_ROLLBACK_INDEX_LOCATIONS; n++) { + uint64_t rollback_index_value = 0; + + if (slot_data[0] != NULL && slot_data[1] != NULL) { + uint64_t a_rollback_index = slot_data[0]->rollback_indexes[n]; + uint64_t b_rollback_index = slot_data[1]->rollback_indexes[n]; + rollback_index_value = + (a_rollback_index < b_rollback_index ? a_rollback_index + : b_rollback_index); + } else if (slot_data[0] != NULL) { + rollback_index_value = slot_data[0]->rollback_indexes[n]; + } else if (slot_data[1] != NULL) { + rollback_index_value = slot_data[1]->rollback_indexes[n]; + } + + if (rollback_index_value != 0) { + uint64_t current_rollback_index_value; + io_ret = ops->read_rollback_index(ops, n, ¤t_rollback_index_value); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + ret = AVB_AB_FLOW_RESULT_ERROR_OOM; + goto out; + } else if (io_ret != AVB_IO_RESULT_OK) { + avb_error("Error getting rollback index for slot.\n"); + ret = AVB_AB_FLOW_RESULT_ERROR_IO; + goto out; + } + if (current_rollback_index_value != rollback_index_value) { + io_ret = ops->write_rollback_index(ops, n, rollback_index_value); + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + ret = AVB_AB_FLOW_RESULT_ERROR_OOM; + goto out; + } else if (io_ret != AVB_IO_RESULT_OK) { + avb_error("Error setting stored rollback index.\n"); + ret = AVB_AB_FLOW_RESULT_ERROR_IO; + goto out; + } + } + } + } + + /* Finally, select this slot. */ + avb_assert(slot_data[slot_index_to_boot] != NULL); + data = slot_data[slot_index_to_boot]; + slot_data[slot_index_to_boot] = NULL; + if (saw_and_allowed_verification_error) { + avb_assert(allow_verification_error); + ret = AVB_AB_FLOW_RESULT_OK_WITH_VERIFICATION_ERROR; + } else { + ret = AVB_AB_FLOW_RESULT_OK; + } + + /* ... and decrement tries remaining, if applicable. */ + if (!ab_data.slots[slot_index_to_boot].successful_boot && + ab_data.slots[slot_index_to_boot].tries_remaining > 0) { + ab_data.slots[slot_index_to_boot].tries_remaining -= 1; + } + +out: + io_ret = save_metadata_if_changed(ab_ops, &ab_data, &ab_data_orig); + if (io_ret != AVB_IO_RESULT_OK) { + if (io_ret == AVB_IO_RESULT_ERROR_OOM) { + ret = AVB_AB_FLOW_RESULT_ERROR_OOM; + } else { + ret = AVB_AB_FLOW_RESULT_ERROR_IO; + } + if (data != NULL) { + avb_slot_verify_data_free(data); + data = NULL; + } + } + + for (n = 0; n < 2; n++) { + if (slot_data[n] != NULL) { + avb_slot_verify_data_free(slot_data[n]); + } + } + + if (out_data != NULL) { + *out_data = data; + } else { + if (data != NULL) { + avb_slot_verify_data_free(data); + } + } + + return ret; +} + +AvbIOResult avb_ab_mark_slot_active(AvbABOps* ab_ops, + unsigned int slot_number) { + AvbABData ab_data, ab_data_orig; + unsigned int other_slot_number; + AvbIOResult ret; + + avb_assert(slot_number < 2); + + ret = load_metadata(ab_ops, &ab_data, &ab_data_orig); + if (ret != AVB_IO_RESULT_OK) { + goto out; + } + + /* Make requested slot top priority, unsuccessful, and with max tries. */ + ab_data.slots[slot_number].priority = AVB_AB_MAX_PRIORITY; + ab_data.slots[slot_number].tries_remaining = AVB_AB_MAX_TRIES_REMAINING; + ab_data.slots[slot_number].successful_boot = 0; + + /* Ensure other slot doesn't have as high a priority. */ + other_slot_number = 1 - slot_number; + if (ab_data.slots[other_slot_number].priority == AVB_AB_MAX_PRIORITY) { + ab_data.slots[other_slot_number].priority = AVB_AB_MAX_PRIORITY - 1; + } + + ret = AVB_IO_RESULT_OK; + +out: + if (ret == AVB_IO_RESULT_OK) { + ret = save_metadata_if_changed(ab_ops, &ab_data, &ab_data_orig); + } + return ret; +} + +AvbIOResult avb_ab_mark_slot_unbootable(AvbABOps* ab_ops, + unsigned int slot_number) { + AvbABData ab_data, ab_data_orig; + AvbIOResult ret; + + avb_assert(slot_number < 2); + + ret = load_metadata(ab_ops, &ab_data, &ab_data_orig); + if (ret != AVB_IO_RESULT_OK) { + goto out; + } + + slot_set_unbootable(&ab_data.slots[slot_number]); + + ret = AVB_IO_RESULT_OK; + +out: + if (ret == AVB_IO_RESULT_OK) { + ret = save_metadata_if_changed(ab_ops, &ab_data, &ab_data_orig); + } + return ret; +} + +AvbIOResult avb_ab_mark_slot_successful(AvbABOps* ab_ops, + unsigned int slot_number) { + AvbABData ab_data, ab_data_orig; + AvbIOResult ret; + + avb_assert(slot_number < 2); + + ret = load_metadata(ab_ops, &ab_data, &ab_data_orig); + if (ret != AVB_IO_RESULT_OK) { + goto out; + } + + if (!slot_is_bootable(&ab_data.slots[slot_number])) { + avb_error("Cannot mark unbootable slot as successful.\n"); + ret = AVB_IO_RESULT_OK; + goto out; + } + + ab_data.slots[slot_number].tries_remaining = 0; + ab_data.slots[slot_number].successful_boot = 1; + + ret = AVB_IO_RESULT_OK; + +out: + if (ret == AVB_IO_RESULT_OK) { + ret = save_metadata_if_changed(ab_ops, &ab_data, &ab_data_orig); + } + return ret; +} + +const char* avb_ab_flow_result_to_string(AvbABFlowResult result) { + const char* ret = NULL; + + switch (result) { + case AVB_AB_FLOW_RESULT_OK: + ret = "OK"; + break; + + case AVB_AB_FLOW_RESULT_OK_WITH_VERIFICATION_ERROR: + ret = "OK_WITH_VERIFICATION_ERROR"; + break; + + case AVB_AB_FLOW_RESULT_ERROR_OOM: + ret = "ERROR_OOM"; + break; + + case AVB_AB_FLOW_RESULT_ERROR_IO: + ret = "ERROR_IO"; + break; + + case AVB_AB_FLOW_RESULT_ERROR_NO_BOOTABLE_SLOTS: + ret = "ERROR_NO_BOOTABLE_SLOTS"; + break; + /* Do not add a 'default:' case here because of -Wswitch. */ + } + + if (ret == NULL) { + avb_error("Unknown AvbABFlowResult value.\n"); + ret = "(unknown)"; + } + + return ret; +} diff --git a/lib/avb/libavb_ab/avb_ab_flow.h b/lib/avb/libavb_ab/avb_ab_flow.h new file mode 100644 index 0000000..b2584d8 --- /dev/null +++ b/lib/avb/libavb_ab/avb_ab_flow.h @@ -0,0 +1,253 @@ +/* + * Copyright (C) 2016 The Android Open Source Project + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, copy, + * modify, merge, publish, distribute, sublicense, and/or sell copies + * of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#if !defined(AVB_INSIDE_LIBAVB_AB_H) && !defined(AVB_COMPILATION) +#error \ + "Never include this file directly, include libavb_ab/libavb_ab.h instead." +#endif + +#ifndef AVB_AB_FLOW_H_ +#define AVB_AB_FLOW_H_ + +#include "avb_ab_ops.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/* Magic for the A/B struct when serialized. */ +#define AVB_AB_MAGIC "\0AB0" +#define AVB_AB_MAGIC_LEN 4 + +/* Versioning for the on-disk A/B metadata - keep in sync with avbtool. */ +#define AVB_AB_MAJOR_VERSION 1 +#define AVB_AB_MINOR_VERSION 0 + +/* Size of AvbABData struct. */ +#define AVB_AB_DATA_SIZE 32 + +/* Maximum values for slot data */ +#define AVB_AB_MAX_PRIORITY 15 +#define AVB_AB_MAX_TRIES_REMAINING 7 + +/* Struct used for recording per-slot metadata. + * + * When serialized, data is stored in network byte-order. + */ +typedef struct AvbABSlotData { + /* Slot priority. Valid values range from 0 to AVB_AB_MAX_PRIORITY, + * both inclusive with 1 being the lowest and AVB_AB_MAX_PRIORITY + * being the highest. The special value 0 is used to indicate the + * slot is unbootable. + */ + uint8_t priority; + + /* Number of times left attempting to boot this slot ranging from 0 + * to AVB_AB_MAX_TRIES_REMAINING. + */ + uint8_t tries_remaining; + + /* Non-zero if this slot has booted successfully, 0 otherwise. */ + uint8_t successful_boot; + + /* Reserved for future use. */ + uint8_t reserved[1]; +} AVB_ATTR_PACKED AvbABSlotData; + +/* Struct used for recording A/B metadata. + * + * When serialized, data is stored in network byte-order. + */ +typedef struct AvbABData { + /* Magic number used for identification - see AVB_AB_MAGIC. */ + uint8_t magic[AVB_AB_MAGIC_LEN]; + + /* Version of on-disk struct - see AVB_AB_{MAJOR,MINOR}_VERSION. */ + uint8_t version_major; + uint8_t version_minor; + + /* Padding to ensure |slots| field start eight bytes in. */ + uint8_t reserved1[2]; + + /* Per-slot metadata. */ + AvbABSlotData slots[2]; + + /* Reserved for future use. */ + uint8_t reserved2[12]; + + /* CRC32 of all 28 bytes preceding this field. */ + uint32_t crc32; +} AVB_ATTR_PACKED AvbABData; + +/* Copies |src| to |dest|, byte-swapping fields in the + * process. Returns false if the data is invalid (e.g. wrong magic, + * wrong CRC32 etc.), true otherwise. + */ +bool avb_ab_data_verify_and_byteswap(const AvbABData* src, AvbABData* dest); + +/* Copies |src| to |dest|, byte-swapping fields in the process. Also + * updates the |crc32| field in |dest|. + */ +void avb_ab_data_update_crc_and_byteswap(const AvbABData* src, AvbABData* dest); + +/* Initializes |data| such that it has two slots and both slots have + * maximum tries remaining. The CRC is not set. + */ +void avb_ab_data_init(AvbABData* data); + +/* Reads A/B metadata from the 'misc' partition using |ops|. Returned + * data is properly byteswapped. Returns AVB_IO_RESULT_OK on + * success, error code otherwise. + * + * If the data read from disk is invalid (e.g. wrong magic or CRC + * checksum failure), the metadata will be reset using + * avb_ab_data_init() and then written to disk. + */ +AvbIOResult avb_ab_data_read(AvbABOps* ab_ops, AvbABData* data); + +/* Writes A/B metadata to the 'misc' partition using |ops|. This will + * byteswap and update the CRC as needed. Returns AVB_IO_RESULT_OK on + * success, error code otherwise. + */ +AvbIOResult avb_ab_data_write(AvbABOps* ab_ops, const AvbABData* data); + +/* Return codes used in avb_ab_flow(), see that function for + * documentation of each value. + */ +typedef enum { + AVB_AB_FLOW_RESULT_OK, + AVB_AB_FLOW_RESULT_OK_WITH_VERIFICATION_ERROR, + AVB_AB_FLOW_RESULT_ERROR_OOM, + AVB_AB_FLOW_RESULT_ERROR_IO, + AVB_AB_FLOW_RESULT_ERROR_NO_BOOTABLE_SLOTS +} AvbABFlowResult; + +/* Get a textual representation of |result|. */ +const char* avb_ab_flow_result_to_string(AvbABFlowResult result); + +/* High-level function to select a slot to boot. The following + * algorithm is used: + * + * 1. A/B metadata is loaded and validated using the + * read_ab_metadata() operation. Typically this means it's read from + * the 'misc' partition and if it's invalid then it's reset using + * avb_ab_data_init() and this reset metadata is returned. + * + * 2. All bootable slots listed in the A/B metadata are verified using + * avb_slot_verify(). If a slot is invalid or if it fails verification + * (and |allow_verification_error| is false, see below), it will be + * marked as unbootable in the A/B metadata and the metadata will be + * saved to disk before returning. + * + * 3. If there are no bootable slots, the value + * AVB_AB_FLOW_RESULT_ERROR_NO_BOOTABLE_SLOTS is returned. + * + * 4. For each bootable slot, the Stored Rollback Indexes are updated + * such that for each rollback index location, the Stored Rollback + * Index is the largest number smaller than or equal to the Rollback + * Index of each slot. + * + * 5. The bootable slot with the highest priority is selected and + * returned in |out_data|. If this slot is already marked as + * successful, the A/B metadata is not modified. However, if the slot + * is not marked as bootable its |tries_remaining| count is + * decremented and the A/B metadata is saved to disk before returning. + * In either case the value AVB_AB_FLOW_RESULT_OK is returning. + * + * The partitions to load is given in |requested_partitions| as a + * NULL-terminated array of NUL-terminated strings. Typically the + * |requested_partitions| array only contains a single item for the + * boot partition, 'boot'. + * + * If the device is unlocked (and _only_ if it's unlocked), true + * should be passed in the |allow_verification_error| parameter. This + * will allow considering slots as verified even when + * avb_slot_verify() returns + * AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED, + * AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION, or + * AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX for the slot in + * question. + * + * Note that androidboot.slot_suffix is not set in the |cmdline| field + * in |AvbSlotVerifyData| - you will have to pass this command-line + * option yourself. + * + * If a slot was selected and it verified then AVB_AB_FLOW_RESULT_OK + * is returned. + * + * If a slot was selected but it didn't verify then + * AVB_AB_FLOW_RESULT_OK_WITH_VERIFICATION_ERROR is returned. This can + * only happen when |allow_verification_error| is true. + * + * If an I/O operation - such as loading/saving metadata or checking + * rollback indexes - fail, the value AVB_AB_FLOW_RESULT_ERROR_IO is + * returned. + * + * If memory allocation fails, AVB_AB_FLOW_RESULT_ERROR_OOM is + * returned. + * + * Reasonable behavior for handling AVB_AB_FLOW_RESULT_ERROR_NO_BOOTABLE_SLOTS + * is to initiate device repair (which is device-dependent). + */ +AvbABFlowResult avb_ab_flow(AvbABOps* ab_ops, + const char* const* requested_partitions, + bool allow_verification_error, + AvbSlotVerifyData** out_data); + +/* Marks the slot with the given slot number as active. Returns + * AVB_IO_RESULT_OK on success, error code otherwise. + * + * This function is typically used by the OS updater when completing + * an update. It can also used by the firmware for implementing the + * "set_active" command. + */ +AvbIOResult avb_ab_mark_slot_active(AvbABOps* ab_ops, unsigned int slot_number); + +/* Marks the slot with the given slot number as unbootable. Returns + * AVB_IO_RESULT_OK on success, error code otherwise. + * + * This function is typically used by the OS updater before writing to + * a slot. + */ +AvbIOResult avb_ab_mark_slot_unbootable(AvbABOps* ab_ops, + unsigned int slot_number); + +/* Marks the slot with the given slot number as having booted + * successfully. Returns AVB_IO_RESULT_OK on success, error code + * otherwise. + * + * Calling this on an unbootable slot is an error - AVB_IO_RESULT_OK + * will be returned yet the function will have no side-effects. + * + * This function is typically used by the OS updater after having + * confirmed that the slot works as intended. + */ +AvbIOResult avb_ab_mark_slot_successful(AvbABOps* ab_ops, + unsigned int slot_number); + +#ifdef __cplusplus +} +#endif + +#endif /* AVB_AB_FLOW_H_ */ diff --git a/lib/avb/libavb_ab/avb_ab_ops.h b/lib/avb/libavb_ab/avb_ab_ops.h new file mode 100644 index 0000000..725c51f --- /dev/null +++ b/lib/avb/libavb_ab/avb_ab_ops.h @@ -0,0 +1,79 @@ +/* + * Copyright (C) 2016 The Android Open Source Project + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, copy, + * modify, merge, publish, distribute, sublicense, and/or sell copies + * of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#if !defined(AVB_INSIDE_LIBAVB_AB_H) && !defined(AVB_COMPILATION) +#error \ + "Never include this file directly, include libavb_ab/libavb_ab.h instead." +#endif + +#ifndef AVB_AB_OPS_H_ +#define AVB_AB_OPS_H_ + +#include "../libavb/libavb.h" + +#ifdef __cplusplus +extern "C" { +#endif + +struct AvbABOps; +typedef struct AvbABOps AvbABOps; + +struct AvbABData; + +/* High-level operations/functions/methods for A/B that are platform + * dependent. + */ +struct AvbABOps { + /* Operations from libavb. */ + AvbOps* ops; + + /* Reads A/B metadata from persistent storage. Returned data is + * properly byteswapped. Returns AVB_IO_RESULT_OK on success, error + * code otherwise. + * + * If the data read is invalid (e.g. wrong magic or CRC checksum + * failure), the metadata shoule be reset using avb_ab_data_init() + * and then written to persistent storage. + * + * Implementations will typically want to use avb_ab_data_read() + * here to use the 'misc' partition for persistent storage. + */ + AvbIOResult (*read_ab_metadata)(AvbABOps* ab_ops, struct AvbABData* data); + + /* Writes A/B metadata to persistent storage. This will byteswap and + * update the CRC as needed. Returns AVB_IO_RESULT_OK on success, + * error code otherwise. + * + * Implementations will typically want to use avb_ab_data_write() + * here to use the 'misc' partition for persistent storage. + */ + AvbIOResult (*write_ab_metadata)(AvbABOps* ab_ops, + const struct AvbABData* data); +}; + +#ifdef __cplusplus +} +#endif + +#endif /* AVB_AB_OPS_H_ */ diff --git a/lib/avb/libavb_ab/libavb_ab.h b/lib/avb/libavb_ab/libavb_ab.h new file mode 100644 index 0000000..970a040 --- /dev/null +++ b/lib/avb/libavb_ab/libavb_ab.h @@ -0,0 +1,40 @@ +/* + * Copyright (C) 2016 The Android Open Source Project + * + * Permission is hereby granted, free of charge, to any person + * obtaining a copy of this software and associated documentation + * files (the "Software"), to deal in the Software without + * restriction, including without limitation the rights to use, copy, + * modify, merge, publish, distribute, sublicense, and/or sell copies + * of the Software, and to permit persons to whom the Software is + * furnished to do so, subject to the following conditions: + * + * The above copyright notice and this permission notice shall be + * included in all copies or substantial portions of the Software. + * + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, + * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF + * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND + * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS + * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN + * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN + * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE + * SOFTWARE. + */ + +#ifndef LIBAVB_AB_H_ +#define LIBAVB_AB_H_ + +#include "../libavb/libavb.h" + +/* The AVB_INSIDE_LIBAVB_AB_H preprocessor symbol is used to enforce + * library users to include only this file. All public interfaces, and + * only public interfaces, must be included here. + */ + +#define AVB_INSIDE_LIBAVB_AB_H +#include "avb_ab_flow.h" +#include "avb_ab_ops.h" +#undef AVB_INSIDE_LIBAVB_AB_H + +#endif /* LIBAVB_AB_H_ */ |