1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * SPDX-License-Identifier: MIT 5 */ 6 7 #include "avb_descriptor.h" 8 #include "avb_util.h" 9 #include "avb_vbmeta_image.h" 10 11 bool avb_descriptor_validate_and_byteswap(const AvbDescriptor* src, 12 AvbDescriptor* dest) { 13 dest->tag = avb_be64toh(src->tag); 14 dest->num_bytes_following = avb_be64toh(src->num_bytes_following); 15 16 if ((dest->num_bytes_following & 0x07) != 0) { 17 avb_error("Descriptor size is not divisible by 8.\n"); 18 return false; 19 } 20 return true; 21 } 22 23 bool avb_descriptor_foreach(const uint8_t* image_data, 24 size_t image_size, 25 AvbDescriptorForeachFunc foreach_func, 26 void* user_data) { 27 const AvbVBMetaImageHeader* header = NULL; 28 bool ret = false; 29 const uint8_t* image_end; 30 const uint8_t* desc_start; 31 const uint8_t* desc_end; 32 const uint8_t* p; 33 34 if (image_data == NULL) { 35 avb_error("image_data is NULL\n."); 36 goto out; 37 } 38 39 if (foreach_func == NULL) { 40 avb_error("foreach_func is NULL\n."); 41 goto out; 42 } 43 44 if (image_size < sizeof(AvbVBMetaImageHeader)) { 45 avb_error("Length is smaller than header.\n"); 46 goto out; 47 } 48 49 /* Ensure magic is correct. */ 50 if (avb_memcmp(image_data, AVB_MAGIC, AVB_MAGIC_LEN) != 0) { 51 avb_error("Magic is incorrect.\n"); 52 goto out; 53 } 54 55 /* Careful, not byteswapped - also ensure it's aligned properly. */ 56 avb_assert_aligned(image_data); 57 header = (const AvbVBMetaImageHeader*)image_data; 58 image_end = image_data + image_size; 59 60 desc_start = image_data + sizeof(AvbVBMetaImageHeader) + 61 avb_be64toh(header->authentication_data_block_size) + 62 avb_be64toh(header->descriptors_offset); 63 64 desc_end = desc_start + avb_be64toh(header->descriptors_size); 65 66 if (desc_start < image_data || desc_start > image_end || 67 desc_end < image_data || desc_end > image_end || desc_end < desc_start) { 68 avb_error("Descriptors not inside passed-in data.\n"); 69 goto out; 70 } 71 72 for (p = desc_start; p < desc_end;) { 73 const AvbDescriptor* dh = (const AvbDescriptor*)p; 74 avb_assert_aligned(dh); 75 uint64_t nb_following = avb_be64toh(dh->num_bytes_following); 76 uint64_t nb_total = sizeof(AvbDescriptor) + nb_following; 77 78 if ((nb_total & 7) != 0) { 79 avb_error("Invalid descriptor length.\n"); 80 goto out; 81 } 82 83 if (nb_total + p < desc_start || nb_total + p > desc_end) { 84 avb_error("Invalid data in descriptors array.\n"); 85 goto out; 86 } 87 88 if (foreach_func(dh, user_data) == 0) { 89 goto out; 90 } 91 92 p += nb_total; 93 } 94 95 ret = true; 96 97 out: 98 return ret; 99 } 100 101 static bool count_descriptors(const AvbDescriptor* descriptor, 102 void* user_data) { 103 size_t* num_descriptors = user_data; 104 *num_descriptors += 1; 105 return true; 106 } 107 108 typedef struct { 109 size_t descriptor_number; 110 const AvbDescriptor** descriptors; 111 } SetDescriptorData; 112 113 static bool set_descriptors(const AvbDescriptor* descriptor, void* user_data) { 114 SetDescriptorData* data = user_data; 115 data->descriptors[data->descriptor_number++] = descriptor; 116 return true; 117 } 118 119 const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data, 120 size_t image_size, 121 size_t* out_num_descriptors) { 122 size_t num_descriptors = 0; 123 SetDescriptorData data; 124 125 avb_descriptor_foreach( 126 image_data, image_size, count_descriptors, &num_descriptors); 127 128 data.descriptor_number = 0; 129 data.descriptors = 130 avb_calloc(sizeof(const AvbDescriptor*) * (num_descriptors + 1)); 131 if (data.descriptors == NULL) { 132 return NULL; 133 } 134 avb_descriptor_foreach(image_data, image_size, set_descriptors, &data); 135 avb_assert(data.descriptor_number == num_descriptors); 136 137 if (out_num_descriptors != NULL) { 138 *out_num_descriptors = num_descriptors; 139 } 140 141 return data.descriptors; 142 } 143