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402 lines
18 KiB
402 lines
18 KiB
/*
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* Copyright (C) 2016 The Android Open Source Project
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use, copy,
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* modify, merge, publish, distribute, sublicense, and/or sell copies
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* of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be
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* included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
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* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
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* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION)
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#error "Never include this file directly, include libavb.h instead."
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#endif
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#ifndef AVB_SLOT_VERIFY_H_
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#define AVB_SLOT_VERIFY_H_
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#include "avb_ops.h"
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#include "avb_vbmeta_image.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/* Return codes used in avb_slot_verify(), see that function for
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* documentation for each field.
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*
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* Use avb_slot_verify_result_to_string() to get a textual
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* representation usable for error/debug output.
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*/
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typedef enum {
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AVB_SLOT_VERIFY_RESULT_OK,
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AVB_SLOT_VERIFY_RESULT_ERROR_OOM,
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AVB_SLOT_VERIFY_RESULT_ERROR_IO,
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AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION,
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AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX,
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AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED,
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AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA,
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AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION,
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AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT
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} AvbSlotVerifyResult;
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/* Various error handling modes for when verification fails using a
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* hashtree at runtime inside the HLOS.
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*
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* AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE means that the OS
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* will invalidate the current slot and restart.
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*
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* AVB_HASHTREE_ERROR_MODE_RESTART means that the OS will restart.
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*
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* AVB_HASHTREE_ERROR_MODE_EIO means that an EIO error will be
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* returned to applications.
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*
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* AVB_HASHTREE_ERROR_MODE_LOGGING means that errors will be logged
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* and corrupt data may be returned to applications. This mode should
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* be used ONLY for diagnostics and debugging. It cannot be used
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* unless AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is also
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* used.
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*
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* AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO means that either
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* AVB_HASHTREE_ERROR_MODE_RESTART or AVB_HASHTREE_ERROR_MODE_EIO is used
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* depending on state. This mode implements a state machine whereby
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* AVB_HASHTREE_ERROR_MODE_RESTART is used by default and when
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* AVB_SLOT_VERIFY_FLAGS_RESTART_CAUSED_BY_HASHTREE_CORRUPTION is passed the
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* mode transitions to AVB_HASHTREE_ERROR_MODE_EIO. When a new OS has been
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* detected the device transitions back to the AVB_HASHTREE_ERROR_MODE_RESTART
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* mode. To do this persistent storage is needed - specifically this means that
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* the passed in AvbOps will need to have the read_persistent_value() and
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* write_persistent_value() operations implemented. The name of the persistent
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* value used is "avb.managed_verity_mode" and 32 bytes of storage is needed.
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*/
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typedef enum {
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AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE,
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AVB_HASHTREE_ERROR_MODE_RESTART,
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AVB_HASHTREE_ERROR_MODE_EIO,
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AVB_HASHTREE_ERROR_MODE_LOGGING,
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AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO,
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AVB_HASHTREE_ERROR_MODE_PANIC
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} AvbHashtreeErrorMode;
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/* Flags that influence how avb_slot_verify() works.
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*
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* If AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is NOT set then
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* avb_slot_verify() will bail out as soon as an error is encountered
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* and |out_data| is set only if AVB_SLOT_VERIFY_RESULT_OK is
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* returned.
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*
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* Otherwise if AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is set
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* avb_slot_verify() will continue verification efforts and |out_data|
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* is also set if AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED,
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* AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION, or
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* AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX is returned. It is
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* undefined which error is returned if more than one distinct error
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* is encountered. It is guaranteed that AVB_SLOT_VERIFY_RESULT_OK is
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* returned if, and only if, there are no errors. This mode is needed
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* to boot valid but unverified slots when the device is unlocked.
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*
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* Also, if AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is set the
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* contents loaded from |requested_partition| will be the contents of
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* the entire partition instead of just the size specified in the hash
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* descriptor.
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*
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* The AVB_SLOT_VERIFY_FLAGS_RESTART_CAUSED_BY_HASHTREE_CORRUPTION flag
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* should be set if using AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO
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* and the reason the boot loader is running is because the device
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* was restarted by the dm-verity driver.
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*
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* If the AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION flag is set then
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* data won't be loaded from the "vbmeta" partition and the
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* |validate_vbmeta_public_key| operation is never called. Instead, the
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* vbmeta structs in |requested_partitions| are loaded and processed and the
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* |validate_public_key_for_partition| operation is called for each of these
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* vbmeta structs. This flag is useful when booting into recovery on a device
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* not using A/B - see section "Booting into recovery" in README.md for
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* more information.
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*/
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typedef enum {
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AVB_SLOT_VERIFY_FLAGS_NONE = 0,
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AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR = (1 << 0),
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AVB_SLOT_VERIFY_FLAGS_RESTART_CAUSED_BY_HASHTREE_CORRUPTION = (1 << 1),
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AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION = (1 << 2),
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} AvbSlotVerifyFlags;
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/* Get a textual representation of |result|. */
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const char* avb_slot_verify_result_to_string(AvbSlotVerifyResult result);
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/* Maximum number of rollback index locations supported. */
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#define AVB_MAX_NUMBER_OF_ROLLBACK_INDEX_LOCATIONS 32
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/* AvbPartitionData contains data loaded from partitions when using
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* avb_slot_verify(). The |partition_name| field contains the name of
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* the partition (without A/B suffix), |data| points to the loaded
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* data which is |data_size| bytes long. If |preloaded| is set to true,
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* this structure dose not own |data|. The caller of |avb_slot_verify|
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* needs to make sure that the preloaded data outlives this
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* |AvbPartitionData| structure.
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*
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* Note that this is strictly less than the partition size - it's only
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* the image stored there, not the entire partition nor any of the
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* metadata.
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*/
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typedef struct {
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char* partition_name;
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uint8_t* data;
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size_t data_size;
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bool preloaded;
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} AvbPartitionData;
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/* AvbVBMetaData contains a vbmeta struct loaded from a partition when
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* using avb_slot_verify(). The |partition_name| field contains the
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* name of the partition (without A/B suffix), |vbmeta_data| points to
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* the loaded data which is |vbmeta_size| bytes long.
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*
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* The |verify_result| field contains the result of
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* avb_vbmeta_image_verify() on the data. This is guaranteed to be
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* AVB_VBMETA_VERIFY_RESULT_OK for all vbmeta images if
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* avb_slot_verify() returns AVB_SLOT_VERIFY_RESULT_OK.
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*
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* You can use avb_descriptor_get_all(), avb_descriptor_foreach(), and
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* avb_vbmeta_image_header_to_host_byte_order() with this data.
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*/
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typedef struct {
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char* partition_name;
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uint8_t* vbmeta_data;
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size_t vbmeta_size;
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AvbVBMetaVerifyResult verify_result;
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} AvbVBMetaData;
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/* AvbSlotVerifyData contains data needed to boot a particular slot
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* and is returned by avb_slot_verify() if partitions in a slot are
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* successfully verified.
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*
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* All data pointed to by this struct - including data in each item in
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* the |partitions| array - will be freed when the
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* avb_slot_verify_data_free() function is called.
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*
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* The |ab_suffix| field is the copy of the of |ab_suffix| field
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* passed to avb_slot_verify(). It is the A/B suffix of the slot. This
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* value includes the leading underscore - typical values are "" (if
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* no slots are in use), "_a" (for the first slot), and "_b" (for the
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* second slot).
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*
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* The VBMeta images that were checked are available in the
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* |vbmeta_images| field. The field |num_vbmeta_images| contains the
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* number of elements in this array. The first element -
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* vbmeta_images[0] - is guaranteed to be from the partition with the
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* top-level vbmeta struct. This is usually the "vbmeta" partition in
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* the requested slot but if there is no "vbmeta" partition it can
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* also be the "boot" partition.
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*
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* The partitions loaded and verified from from the slot are
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* accessible in the |loaded_partitions| array. The field
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* |num_loaded_partitions| contains the number of elements in this
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* array. The order of partitions in this array may not necessarily be
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* the same order as in the passed-in |requested_partitions| array.
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*
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* Rollback indexes for the verified slot are stored in the
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* |rollback_indexes| field. Note that avb_slot_verify() will NEVER
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* modify stored_rollback_index[n] locations e.g. it will never use
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* the write_rollback_index() AvbOps operation. Instead it is the job
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* of the caller of avb_slot_verify() to do this based on e.g. A/B
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* policy and other factors. See libavb_ab/avb_ab_flow.c for an
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* example of how to do this.
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*
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* The |cmdline| field is a NUL-terminated string in UTF-8 resulting
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* from concatenating all |AvbKernelCmdlineDescriptor| and then
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* performing proper substitution of the variables
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* $(ANDROID_SYSTEM_PARTUUID), $(ANDROID_BOOT_PARTUUID), and
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* $(ANDROID_VBMETA_PARTUUID) using the
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* get_unique_guid_for_partition() operation in |AvbOps|. Additionally
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* $(ANDROID_VERITY_MODE) will be replaced with the proper dm-verity
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* option depending on the value of |hashtree_error_mode|.
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*
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* Additionally, the |cmdline| field will have the following kernel
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* command-line options set (unless verification is disabled, see
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* below):
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*
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* androidboot.veritymode: This is set to 'disabled' if the
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* AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED flag is set in top-level
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* vbmeta struct. Otherwise it is set to 'enforcing' if the
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* passed-in hashtree error mode is AVB_HASHTREE_ERROR_MODE_RESTART
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* or AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE, 'eio' if it's
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* set to AVB_HASHTREE_ERROR_MODE_EIO, and 'logging' if it's set to
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* AVB_HASHTREE_ERROR_MODE_LOGGING.
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*
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* androidboot.veritymode.managed: This is set to 'yes' only
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* if hashtree validation isn't disabled and the passed-in hashtree
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* error mode is AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO.
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*
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* androidboot.vbmeta.invalidate_on_error: This is set to 'yes' only
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* if hashtree validation isn't disabled and the passed-in hashtree
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* error mode is AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE.
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*
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* androidboot.vbmeta.device_state: set to "locked" or "unlocked"
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* depending on the result of the result of AvbOps's
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* read_is_unlocked() function.
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*
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* androidboot.vbmeta.{hash_alg, size, digest}: Will be set to
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* the digest of all images in |vbmeta_images|.
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*
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* androidboot.vbmeta.device: This is set to the value
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* PARTUUID=$(ANDROID_VBMETA_PARTUUID) before substitution so it
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* will end up pointing to the vbmeta partition for the verified
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* slot. If there is no vbmeta partition it will point to the boot
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* partition of the verified slot. If the flag
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* AVB_SLOT_VERIFY_FLAGS_NO_VBMETA_PARTITION is used, this is not
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* set.
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*
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* androidboot.vbmeta.avb_version: This is set to the decimal value
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* of AVB_VERSION_MAJOR followed by a dot followed by the decimal
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* value of AVB_VERSION_MINOR, for example "1.0" or "1.4". This
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* version number represents the vbmeta file format version
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* supported by libavb copy used in the boot loader. This is not
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* necessarily the same version number of the on-disk metadata for
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* the slot that was verified.
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*
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* Note that androidboot.slot_suffix is not set in the |cmdline| field
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* in |AvbSlotVerifyData| - you will have to set this yourself.
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*
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* If the |AVB_VBMETA_IMAGE_FLAGS_VERIFICATION_DISABLED| flag is set
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* in the top-level vbmeta struct then only the top-level vbmeta
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* struct is verified and descriptors will not processed. The return
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* value will be set accordingly (if this flag is set via 'avbctl
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* disable-verification' then the return value will be
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* |AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION|) and
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* |AvbSlotVerifyData| is returned. Additionally all partitions in the
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* |requested_partitions| are loaded and the |cmdline| field is set to
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* "root=PARTUUID=$(ANDROID_SYSTEM_PARTUUID)" and the GUID for the
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* appropriate system partition is substituted in. Note that none of
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* the androidboot.* options mentioned above will be set.
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*
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* The |resolved_hashtree_error_mode| is the the value of the passed
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* avb_slot_verify()'s |hashtree_error_mode| parameter except that it never has
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* the value AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO. If this value was
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* passed in, then the restart/eio state machine is used resulting in
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* |resolved_hashtree_error_mode| being set to either
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* AVB_HASHTREE_ERROR_MODE_RESTART or AVB_HASHTREE_ERROR_MODE_EIO. If set to
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* AVB_HASHTREE_ERROR_MODE_EIO the boot loader should present a RED warning
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* screen for the user to click through before continuing to boot.
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*
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* This struct may grow in the future without it being considered an
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* ABI break.
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*/
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typedef struct {
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char* ab_suffix;
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AvbVBMetaData* vbmeta_images;
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size_t num_vbmeta_images;
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AvbPartitionData* loaded_partitions;
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size_t num_loaded_partitions;
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char* cmdline;
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uint64_t rollback_indexes[AVB_MAX_NUMBER_OF_ROLLBACK_INDEX_LOCATIONS];
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AvbHashtreeErrorMode resolved_hashtree_error_mode;
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} AvbSlotVerifyData;
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/* Calculates a digest of all vbmeta images in |data| using
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* the digest indicated by |digest_type|. Stores the result
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* in |out_digest| which must be large enough to hold a digest
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* of the requested type.
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*/
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void avb_slot_verify_data_calculate_vbmeta_digest(AvbSlotVerifyData* data,
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AvbDigestType digest_type,
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uint8_t* out_digest);
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/* Frees a |AvbSlotVerifyData| including all data it points to. */
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void avb_slot_verify_data_free(AvbSlotVerifyData* data);
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/* Performs a full verification of the slot identified by |ab_suffix|
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* and load and verify the contents of the partitions whose name is in
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* the NULL-terminated string array |requested_partitions| (each
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* partition must use hash verification). If not using A/B, pass an
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* empty string (e.g. "", not NULL) for |ab_suffix|. This parameter
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* must include the leading underscore, for example "_a" should be
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* used to refer to the first slot.
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*
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* Typically the |requested_partitions| array only contains a single
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* item for the boot partition, 'boot'.
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*
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* Verification includes loading and verifying data from the 'vbmeta',
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* the requested hash partitions, and possibly other partitions (with
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* |ab_suffix| appended), inspecting rollback indexes, and checking if
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* the public key used to sign the data is acceptable. The functions
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* in |ops| will be used to do this.
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*
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* If |out_data| is not NULL, it will be set to a newly allocated
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* |AvbSlotVerifyData| struct containing all the data needed to
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* actually boot the slot. This data structure should be freed with
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* avb_slot_verify_data_free() when you are done with it. See below
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* for when this is returned.
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*
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* The |flags| parameter is used to influence the semantics of
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* avb_slot_verify() - for example the
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* AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR flag can be used to
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* ignore verification errors which is something needed in the
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* UNLOCKED state. See the AvbSlotVerifyFlags enumeration for details.
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*
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* The |hashtree_error_mode| parameter should be set to the desired error
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* handling mode. See the AvbHashtreeErrorMode enumeration for details.
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*
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* Also note that |out_data| is never set if
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* AVB_SLOT_VERIFY_RESULT_ERROR_OOM, AVB_SLOT_VERIFY_RESULT_ERROR_IO,
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* or AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA is returned.
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*
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* AVB_SLOT_VERIFY_RESULT_OK is returned if everything is verified
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* correctly and all public keys are accepted.
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*
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* AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED is returned if
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* everything is verified correctly out but one or more public keys
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* are not accepted. This includes the case where integrity data is
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* not signed.
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*
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* AVB_SLOT_VERIFY_RESULT_ERROR_OOM is returned if unable to
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* allocate memory.
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*
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* AVB_SLOT_VERIFY_RESULT_ERROR_IO is returned if an I/O error
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* occurred while trying to load data or get a rollback index.
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*
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* AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION is returned if the data
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* did not verify, e.g. the digest didn't match or signature checks
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* failed.
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*
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* AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX is returned if a
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* rollback index was less than its stored value.
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*
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* AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA is returned if some
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* of the metadata is invalid or inconsistent.
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*
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* AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION is returned if
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* some of the metadata requires a newer version of libavb than what
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* is in use.
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*
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* AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT is returned if the
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* caller passed invalid parameters, for example trying to use
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* AVB_HASHTREE_ERROR_MODE_LOGGING without
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* AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR.
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*/
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AvbSlotVerifyResult avb_slot_verify(AvbOps* ops,
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const char* const* requested_partitions,
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const char* ab_suffix,
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AvbSlotVerifyFlags flags,
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AvbHashtreeErrorMode hashtree_error_mode,
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AvbSlotVerifyData** out_data);
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#ifdef __cplusplus
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}
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#endif
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#endif /* AVB_SLOT_VERIFY_H_ */
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