avb_descriptor.h
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/* SPDX-License-Identifier: MIT */
/*
* Copyright (C) 2016 The Android Open Source Project
*/
#if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION)
#error "Never include this file directly, include libavb.h instead."
#endif
#ifndef AVB_DESCRIPTOR_H_
#define AVB_DESCRIPTOR_H_
#include "avb_sysdeps.h"
#ifdef __cplusplus
extern "C" {
#endif
/* Well-known descriptor tags.
*
* AVB_DESCRIPTOR_TAG_PROPERTY: see |AvbPropertyDescriptor| struct.
* AVB_DESCRIPTOR_TAG_HASHTREE: see |AvbHashtreeDescriptor| struct.
* AVB_DESCRIPTOR_TAG_HASH: see |AvbHashDescriptor| struct.
* AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE: see |AvbKernelCmdlineDescriptor| struct.
* AVB_DESCRIPTOR_TAG_CHAIN_PARTITION: see |AvbChainPartitionDescriptor| struct.
*/
typedef enum {
AVB_DESCRIPTOR_TAG_PROPERTY,
AVB_DESCRIPTOR_TAG_HASHTREE,
AVB_DESCRIPTOR_TAG_HASH,
AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE,
AVB_DESCRIPTOR_TAG_CHAIN_PARTITION,
} AvbDescriptorTag;
/* The header for a serialized descriptor.
*
* A descriptor always have two fields, a |tag| (denoting its type,
* see the |AvbDescriptorTag| enumeration) and the size of the bytes
* following, |num_bytes_following|.
*
* For padding, |num_bytes_following| is always a multiple of 8.
*/
typedef struct AvbDescriptor {
uint64_t tag;
uint64_t num_bytes_following;
} AVB_ATTR_PACKED AvbDescriptor;
/* Copies |src| to |dest| and validates, byte-swapping fields in the
* process if needed. Returns true if valid, false if invalid.
*
* Data following the struct is not validated nor copied.
*/
bool avb_descriptor_validate_and_byteswap(
const AvbDescriptor* src, AvbDescriptor* dest) AVB_ATTR_WARN_UNUSED_RESULT;
/* Signature for callback function used in avb_descriptor_foreach().
* The passed in descriptor is given by |descriptor| and the
* |user_data| passed to avb_descriptor_foreach() function is in
* |user_data|. Return true to continue iterating, false to stop
* iterating.
*
* Note that |descriptor| points into the image passed to
* avb_descriptor_foreach() - all fields need to be byteswapped!
*/
typedef bool AvbDescriptorForeachFunc(const AvbDescriptor* descriptor,
void* user_data);
/* Convenience function to iterate over all descriptors in an vbmeta
* image.
*
* The function given by |foreach_func| will be called for each
* descriptor. The given function should return true to continue
* iterating, false to stop.
*
* The |user_data| parameter will be passed to |foreach_func|.
*
* Returns false if the iteration was short-circuited, that is if
* an invocation of |foreach_func| returned false.
*
* Before using this function, you MUST verify |image_data| with
* avb_vbmeta_image_verify() and reject it unless it's signed by a known
* good public key. Additionally, |image_data| must be word-aligned.
*/
bool avb_descriptor_foreach(const uint8_t* image_data,
size_t image_size,
AvbDescriptorForeachFunc foreach_func,
void* user_data);
/* Gets all descriptors in a vbmeta image.
*
* The return value is a NULL-pointer terminated array of
* AvbDescriptor pointers. Free with avb_free() when you are done with
* it. If |out_num_descriptors| is non-NULL, the number of descriptors
* will be returned there.
*
* Note that each AvbDescriptor pointer in the array points into
* |image_data| - all fields need to be byteswapped!
*
* Before using this function, you MUST verify |image_data| with
* avb_vbmeta_image_verify() and reject it unless it's signed by a known
* good public key. Additionally, |image_data| must be word-aligned.
*/
const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data,
size_t image_size,
size_t* out_num_descriptors)
AVB_ATTR_WARN_UNUSED_RESULT;
#ifdef __cplusplus
}
#endif
#endif /* AVB_DESCRIPTOR_H_ */