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 #include <android_avb/avb_descriptor.h> 26 #include <android_avb/avb_util.h> 27 #include <android_avb/avb_vbmeta_image.h> 28 29 bool avb_descriptor_validate_and_byteswap(const AvbDescriptor* src, 30 AvbDescriptor* dest) { 31 dest->tag = avb_be64toh(src->tag); 32 dest->num_bytes_following = avb_be64toh(src->num_bytes_following); 33 34 if ((dest->num_bytes_following & 0x07) != 0) { 35 avb_error("Descriptor size is not divisible by 8.\n"); 36 return false; 37 } 38 return true; 39 } 40 41 bool avb_descriptor_foreach(const uint8_t* image_data, 42 size_t image_size, 43 AvbDescriptorForeachFunc foreach_func, 44 void* user_data) { 45 const AvbVBMetaImageHeader* header = NULL; 46 bool ret = false; 47 const uint8_t* image_end; 48 const uint8_t* desc_start; 49 const uint8_t* desc_end; 50 const uint8_t* p; 51 52 if (image_data == NULL) { 53 avb_error("image_data is NULL\n."); 54 goto out; 55 } 56 57 if (foreach_func == NULL) { 58 avb_error("foreach_func is NULL\n."); 59 goto out; 60 } 61 62 if (image_size < sizeof(AvbVBMetaImageHeader)) { 63 avb_error("Length is smaller than header.\n"); 64 goto out; 65 } 66 67 /* Ensure magic is correct. */ 68 if (avb_memcmp(image_data, AVB_MAGIC, AVB_MAGIC_LEN) != 0) { 69 avb_error("Magic is incorrect.\n"); 70 goto out; 71 } 72 73 /* Careful, not byteswapped - also ensure it's aligned properly. */ 74 avb_assert_aligned(image_data); 75 header = (const AvbVBMetaImageHeader*)image_data; 76 image_end = image_data + image_size; 77 78 desc_start = image_data + sizeof(AvbVBMetaImageHeader) + 79 avb_be64toh(header->authentication_data_block_size) + 80 avb_be64toh(header->descriptors_offset); 81 82 desc_end = desc_start + avb_be64toh(header->descriptors_size); 83 84 if (desc_start < image_data || desc_start > image_end || 85 desc_end < image_data || desc_end > image_end || desc_end < desc_start) { 86 avb_error("Descriptors not inside passed-in data.\n"); 87 goto out; 88 } 89 90 for (p = desc_start; p < desc_end;) { 91 const AvbDescriptor* dh = (const AvbDescriptor*)p; 92 avb_assert_aligned(dh); 93 uint64_t nb_following = avb_be64toh(dh->num_bytes_following); 94 uint64_t nb_total = 0; 95 if (!avb_safe_add(&nb_total, sizeof(AvbDescriptor), nb_following)) { 96 avb_error("Invalid descriptor length.\n"); 97 goto out; 98 } 99 100 if ((nb_total & 7) != 0) { 101 avb_error("Invalid descriptor length.\n"); 102 goto out; 103 } 104 105 if (nb_total + p < desc_start || nb_total + p > desc_end) { 106 avb_error("Invalid data in descriptors array.\n"); 107 goto out; 108 } 109 110 if (foreach_func(dh, user_data) == 0) { 111 goto out; 112 } 113 114 if (!avb_safe_add_to((uint64_t*)(&p), nb_total)) { 115 avb_error("Invalid descriptor length.\n"); 116 goto out; 117 } 118 } 119 120 ret = true; 121 122 out: 123 return ret; 124 } 125 126 static bool count_descriptors(const AvbDescriptor* descriptor, 127 void* user_data) { 128 size_t* num_descriptors = user_data; 129 *num_descriptors += 1; 130 return true; 131 } 132 133 typedef struct { 134 size_t descriptor_number; 135 const AvbDescriptor** descriptors; 136 } SetDescriptorData; 137 138 static bool set_descriptors(const AvbDescriptor* descriptor, void* user_data) { 139 SetDescriptorData* data = user_data; 140 data->descriptors[data->descriptor_number++] = descriptor; 141 return true; 142 } 143 144 const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data, 145 size_t image_size, 146 size_t* out_num_descriptors) { 147 size_t num_descriptors = 0; 148 SetDescriptorData data; 149 150 avb_descriptor_foreach( 151 image_data, image_size, count_descriptors, &num_descriptors); 152 153 data.descriptor_number = 0; 154 data.descriptors = 155 avb_calloc(sizeof(const AvbDescriptor*) * (num_descriptors + 1)); 156 if (data.descriptors == NULL) { 157 return NULL; 158 } 159 avb_descriptor_foreach(image_data, image_size, set_descriptors, &data); 160 avb_assert(data.descriptor_number == num_descriptors); 161 162 if (out_num_descriptors != NULL) { 163 *out_num_descriptors = num_descriptors; 164 } 165 166 return data.descriptors; 167 } 168