1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Permission is hereby granted, free of charge, to any person 5 * obtaining a copy of this software and associated documentation 6 * files (the "Software"), to deal in the Software without 7 * restriction, including without limitation the rights to use, copy, 8 * modify, merge, publish, distribute, sublicense, and/or sell copies 9 * of the Software, and to permit persons to whom the Software is 10 * furnished to do so, subject to the following conditions: 11 * 12 * The above copyright notice and this permission notice shall be 13 * included in all copies or substantial portions of the Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 * SOFTWARE. 23 */ 24 25 #if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION) 26 #error "Never include this file directly, include libavb.h instead." 27 #endif 28 29 #ifndef AVB_DESCRIPTOR_H_ 30 #define AVB_DESCRIPTOR_H_ 31 32 #include "avb_sysdeps.h" 33 34 #ifdef __cplusplus 35 extern "C" { 36 #endif 37 38 /* Well-known descriptor tags. 39 * 40 * AVB_DESCRIPTOR_TAG_PROPERTY: see |AvbPropertyDescriptor| struct. 41 * AVB_DESCRIPTOR_TAG_HASHTREE: see |AvbHashtreeDescriptor| struct. 42 * AVB_DESCRIPTOR_TAG_HASH: see |AvbHashDescriptor| struct. 43 * AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE: see |AvbKernelCmdlineDescriptor| struct. 44 * AVB_DESCRIPTOR_TAG_CHAIN_PARTITION: see |AvbChainPartitionDescriptor| struct. 45 */ 46 typedef enum { 47 AVB_DESCRIPTOR_TAG_PROPERTY, 48 AVB_DESCRIPTOR_TAG_HASHTREE, 49 AVB_DESCRIPTOR_TAG_HASH, 50 AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE, 51 AVB_DESCRIPTOR_TAG_CHAIN_PARTITION, 52 } AvbDescriptorTag; 53 54 /* The header for a serialized descriptor. 55 * 56 * A descriptor always have two fields, a |tag| (denoting its type, 57 * see the |AvbDescriptorTag| enumeration) and the size of the bytes 58 * following, |num_bytes_following|. 59 * 60 * For padding, |num_bytes_following| is always a multiple of 8. 61 */ 62 typedef struct AvbDescriptor { 63 uint64_t tag; 64 uint64_t num_bytes_following; 65 } AVB_ATTR_PACKED AvbDescriptor; 66 67 /* Copies |src| to |dest| and validates, byte-swapping fields in the 68 * process if needed. Returns true if valid, false if invalid. 69 * 70 * Data following the struct is not validated nor copied. 71 */ 72 bool avb_descriptor_validate_and_byteswap( 73 const AvbDescriptor* src, AvbDescriptor* dest) AVB_ATTR_WARN_UNUSED_RESULT; 74 75 /* Signature for callback function used in avb_descriptor_foreach(). 76 * The passed in descriptor is given by |descriptor| and the 77 * |user_data| passed to avb_descriptor_foreach() function is in 78 * |user_data|. Return true to continue iterating, false to stop 79 * iterating. 80 * 81 * Note that |descriptor| points into the image passed to 82 * avb_descriptor_foreach() - all fields need to be byteswapped! 83 */ 84 typedef bool AvbDescriptorForeachFunc(const AvbDescriptor* descriptor, 85 void* user_data); 86 87 /* Convenience function to iterate over all descriptors in an vbmeta 88 * image. 89 * 90 * The function given by |foreach_func| will be called for each 91 * descriptor. The given function should return true to continue 92 * iterating, false to stop. 93 * 94 * The |user_data| parameter will be passed to |foreach_func|. 95 * 96 * Returns false if the iteration was short-circuited, that is if 97 * an invocation of |foreach_func| returned false. 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 bool avb_descriptor_foreach(const uint8_t* image_data, 104 size_t image_size, 105 AvbDescriptorForeachFunc foreach_func, 106 void* user_data); 107 108 /* Gets all descriptors in a vbmeta image. 109 * 110 * The return value is a NULL-pointer terminated array of 111 * AvbDescriptor pointers. Free with avb_free() when you are done with 112 * it. If |out_num_descriptors| is non-NULL, the number of descriptors 113 * will be returned there. 114 * 115 * Note that each AvbDescriptor pointer in the array points into 116 * |image_data| - all fields need to be byteswapped! 117 * 118 * Before using this function, you MUST verify |image_data| with 119 * avb_vbmeta_image_verify() and reject it unless it's signed by a known 120 * good public key. Additionally, |image_data| must be word-aligned. 121 */ 122 const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data, 123 size_t image_size, 124 size_t* out_num_descriptors) 125 AVB_ATTR_WARN_UNUSED_RESULT; 126 127 #ifdef __cplusplus 128 } 129 #endif 130 131 #endif /* AVB_DESCRIPTOR_H_ */ 132