1 /* SPDX-License-Identifier: MIT */ 2 /* 3 * Copyright (C) 2016 The Android Open Source Project 4 */ 5 6 #if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION) 7 #error "Never include this file directly, include libavb.h instead." 8 #endif 9 10 #ifndef AVB_DESCRIPTOR_H_ 11 #define AVB_DESCRIPTOR_H_ 12 13 #include "avb_sysdeps.h" 14 15 #ifdef __cplusplus 16 extern "C" { 17 #endif 18 19 /* Well-known descriptor tags. 20 * 21 * AVB_DESCRIPTOR_TAG_PROPERTY: see |AvbPropertyDescriptor| struct. 22 * AVB_DESCRIPTOR_TAG_HASHTREE: see |AvbHashtreeDescriptor| struct. 23 * AVB_DESCRIPTOR_TAG_HASH: see |AvbHashDescriptor| struct. 24 * AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE: see |AvbKernelCmdlineDescriptor| struct. 25 * AVB_DESCRIPTOR_TAG_CHAIN_PARTITION: see |AvbChainPartitionDescriptor| struct. 26 */ 27 typedef enum { 28 AVB_DESCRIPTOR_TAG_PROPERTY, 29 AVB_DESCRIPTOR_TAG_HASHTREE, 30 AVB_DESCRIPTOR_TAG_HASH, 31 AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE, 32 AVB_DESCRIPTOR_TAG_CHAIN_PARTITION, 33 } AvbDescriptorTag; 34 35 /* The header for a serialized descriptor. 36 * 37 * A descriptor always have two fields, a |tag| (denoting its type, 38 * see the |AvbDescriptorTag| enumeration) and the size of the bytes 39 * following, |num_bytes_following|. 40 * 41 * For padding, |num_bytes_following| is always a multiple of 8. 42 */ 43 typedef struct AvbDescriptor { 44 uint64_t tag; 45 uint64_t num_bytes_following; 46 } AVB_ATTR_PACKED AvbDescriptor; 47 48 /* Copies |src| to |dest| and validates, byte-swapping fields in the 49 * process if needed. Returns true if valid, false if invalid. 50 * 51 * Data following the struct is not validated nor copied. 52 */ 53 bool avb_descriptor_validate_and_byteswap( 54 const AvbDescriptor* src, AvbDescriptor* dest) AVB_ATTR_WARN_UNUSED_RESULT; 55 56 /* Signature for callback function used in avb_descriptor_foreach(). 57 * The passed in descriptor is given by |descriptor| and the 58 * |user_data| passed to avb_descriptor_foreach() function is in 59 * |user_data|. Return true to continue iterating, false to stop 60 * iterating. 61 * 62 * Note that |descriptor| points into the image passed to 63 * avb_descriptor_foreach() - all fields need to be byteswapped! 64 */ 65 typedef bool AvbDescriptorForeachFunc(const AvbDescriptor* descriptor, 66 void* user_data); 67 68 /* Convenience function to iterate over all descriptors in an vbmeta 69 * image. 70 * 71 * The function given by |foreach_func| will be called for each 72 * descriptor. The given function should return true to continue 73 * iterating, false to stop. 74 * 75 * The |user_data| parameter will be passed to |foreach_func|. 76 * 77 * Returns false if the iteration was short-circuited, that is if 78 * an invocation of |foreach_func| returned false. 79 * 80 * Before using this function, you MUST verify |image_data| with 81 * avb_vbmeta_image_verify() and reject it unless it's signed by a known 82 * good public key. Additionally, |image_data| must be word-aligned. 83 */ 84 bool avb_descriptor_foreach(const uint8_t* image_data, 85 size_t image_size, 86 AvbDescriptorForeachFunc foreach_func, 87 void* user_data); 88 89 /* Gets all descriptors in a vbmeta image. 90 * 91 * The return value is a NULL-pointer terminated array of 92 * AvbDescriptor pointers. Free with avb_free() when you are done with 93 * it. If |out_num_descriptors| is non-NULL, the number of descriptors 94 * will be returned there. 95 * 96 * Note that each AvbDescriptor pointer in the array points into 97 * |image_data| - all fields need to be byteswapped! 98 * 99 * Before using this function, you MUST verify |image_data| with 100 * avb_vbmeta_image_verify() and reject it unless it's signed by a known 101 * good public key. Additionally, |image_data| must be word-aligned. 102 */ 103 const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data, 104 size_t image_size, 105 size_t* out_num_descriptors) 106 AVB_ATTR_WARN_UNUSED_RESULT; 107 108 #ifdef __cplusplus 109 } 110 #endif 111 112 #endif /* AVB_DESCRIPTOR_H_ */ 113