1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * SPDX-License-Identifier: MIT 5 */ 6 7 #if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION) 8 #error "Never include this file directly, include libavb.h instead." 9 #endif 10 11 #ifndef AVB_DESCRIPTOR_H_ 12 #define AVB_DESCRIPTOR_H_ 13 14 #include "avb_sysdeps.h" 15 16 #ifdef __cplusplus 17 extern "C" { 18 #endif 19 20 /* Well-known descriptor tags. 21 * 22 * AVB_DESCRIPTOR_TAG_PROPERTY: see |AvbPropertyDescriptor| struct. 23 * AVB_DESCRIPTOR_TAG_HASHTREE: see |AvbHashtreeDescriptor| struct. 24 * AVB_DESCRIPTOR_TAG_HASH: see |AvbHashDescriptor| struct. 25 * AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE: see |AvbKernelCmdlineDescriptor| struct. 26 * AVB_DESCRIPTOR_TAG_CHAIN_PARTITION: see |AvbChainPartitionDescriptor| struct. 27 */ 28 typedef enum { 29 AVB_DESCRIPTOR_TAG_PROPERTY, 30 AVB_DESCRIPTOR_TAG_HASHTREE, 31 AVB_DESCRIPTOR_TAG_HASH, 32 AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE, 33 AVB_DESCRIPTOR_TAG_CHAIN_PARTITION, 34 } AvbDescriptorTag; 35 36 /* The header for a serialized descriptor. 37 * 38 * A descriptor always have two fields, a |tag| (denoting its type, 39 * see the |AvbDescriptorTag| enumeration) and the size of the bytes 40 * following, |num_bytes_following|. 41 * 42 * For padding, |num_bytes_following| is always a multiple of 8. 43 */ 44 typedef struct AvbDescriptor { 45 uint64_t tag; 46 uint64_t num_bytes_following; 47 } AVB_ATTR_PACKED AvbDescriptor; 48 49 /* Copies |src| to |dest| and validates, byte-swapping fields in the 50 * process if needed. Returns true if valid, false if invalid. 51 * 52 * Data following the struct is not validated nor copied. 53 */ 54 bool avb_descriptor_validate_and_byteswap( 55 const AvbDescriptor* src, AvbDescriptor* dest) AVB_ATTR_WARN_UNUSED_RESULT; 56 57 /* Signature for callback function used in avb_descriptor_foreach(). 58 * The passed in descriptor is given by |descriptor| and the 59 * |user_data| passed to avb_descriptor_foreach() function is in 60 * |user_data|. Return true to continue iterating, false to stop 61 * iterating. 62 * 63 * Note that |descriptor| points into the image passed to 64 * avb_descriptor_foreach() - all fields need to be byteswapped! 65 */ 66 typedef bool AvbDescriptorForeachFunc(const AvbDescriptor* descriptor, 67 void* user_data); 68 69 /* Convenience function to iterate over all descriptors in an vbmeta 70 * image. 71 * 72 * The function given by |foreach_func| will be called for each 73 * descriptor. The given function should return true to continue 74 * iterating, false to stop. 75 * 76 * The |user_data| parameter will be passed to |foreach_func|. 77 * 78 * Returns false if the iteration was short-circuited, that is if 79 * an invocation of |foreach_func| returned false. 80 * 81 * Before using this function, you MUST verify |image_data| with 82 * avb_vbmeta_image_verify() and reject it unless it's signed by a known 83 * good public key. Additionally, |image_data| must be word-aligned. 84 */ 85 bool avb_descriptor_foreach(const uint8_t* image_data, 86 size_t image_size, 87 AvbDescriptorForeachFunc foreach_func, 88 void* user_data); 89 90 /* Gets all descriptors in a vbmeta image. 91 * 92 * The return value is a NULL-pointer terminated array of 93 * AvbDescriptor pointers. Free with avb_free() when you are done with 94 * it. If |out_num_descriptors| is non-NULL, the number of descriptors 95 * will be returned there. 96 * 97 * Note that each AvbDescriptor pointer in the array points into 98 * |image_data| - all fields need to be byteswapped! 99 * 100 * Before using this function, you MUST verify |image_data| with 101 * avb_vbmeta_image_verify() and reject it unless it's signed by a known 102 * good public key. Additionally, |image_data| must be word-aligned. 103 */ 104 const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data, 105 size_t image_size, 106 size_t* out_num_descriptors) 107 AVB_ATTR_WARN_UNUSED_RESULT; 108 109 #ifdef __cplusplus 110 } 111 #endif 112 113 #endif /* AVB_DESCRIPTOR_H_ */ 114