1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * SPDX-License-Identifier: MIT 5 */ 6 7 #include "avb_property_descriptor.h" 8 #include "avb_util.h" 9 10 bool avb_property_descriptor_validate_and_byteswap( 11 const AvbPropertyDescriptor* src, AvbPropertyDescriptor* dest) { 12 uint64_t expected_size; 13 14 avb_memcpy(dest, src, sizeof(AvbPropertyDescriptor)); 15 16 if (!avb_descriptor_validate_and_byteswap((const AvbDescriptor*)src, 17 (AvbDescriptor*)dest)) 18 return false; 19 20 if (dest->parent_descriptor.tag != AVB_DESCRIPTOR_TAG_PROPERTY) { 21 avb_error("Invalid tag for property descriptor.\n"); 22 return false; 23 } 24 25 dest->key_num_bytes = avb_be64toh(dest->key_num_bytes); 26 dest->value_num_bytes = avb_be64toh(dest->value_num_bytes); 27 28 /* Check that key and value are fully contained. */ 29 expected_size = sizeof(AvbPropertyDescriptor) - sizeof(AvbDescriptor) + 2; 30 if (!avb_safe_add_to(&expected_size, dest->key_num_bytes) || 31 !avb_safe_add_to(&expected_size, dest->value_num_bytes)) { 32 avb_error("Overflow while adding up sizes.\n"); 33 return false; 34 } 35 if (expected_size > dest->parent_descriptor.num_bytes_following) { 36 avb_error("Descriptor payload size overflow.\n"); 37 return false; 38 } 39 40 return true; 41 } 42 43 typedef struct { 44 const char* key; 45 size_t key_size; 46 const char* ret_value; 47 size_t ret_value_size; 48 } PropertyIteratorData; 49 50 static bool property_lookup_desc_foreach(const AvbDescriptor* header, 51 void* user_data) { 52 PropertyIteratorData* data = (PropertyIteratorData*)user_data; 53 AvbPropertyDescriptor prop_desc; 54 const uint8_t* p; 55 bool ret = true; 56 57 if (header->tag != AVB_DESCRIPTOR_TAG_PROPERTY) { 58 goto out; 59 } 60 61 if (!avb_property_descriptor_validate_and_byteswap( 62 (const AvbPropertyDescriptor*)header, &prop_desc)) { 63 goto out; 64 } 65 66 p = (const uint8_t*)header; 67 if (p[sizeof(AvbPropertyDescriptor) + prop_desc.key_num_bytes] != 0) { 68 avb_error("No terminating NUL byte in key.\n"); 69 goto out; 70 } 71 72 if (data->key_size == prop_desc.key_num_bytes) { 73 if (avb_memcmp(p + sizeof(AvbPropertyDescriptor), 74 data->key, 75 data->key_size) == 0) { 76 data->ret_value = (const char*)(p + sizeof(AvbPropertyDescriptor) + 77 prop_desc.key_num_bytes + 1); 78 data->ret_value_size = prop_desc.value_num_bytes; 79 /* Stop iterating. */ 80 ret = false; 81 goto out; 82 } 83 } 84 85 out: 86 return ret; 87 } 88 89 const char* avb_property_lookup(const uint8_t* image_data, 90 size_t image_size, 91 const char* key, 92 size_t key_size, 93 size_t* out_value_size) { 94 PropertyIteratorData data; 95 96 if (key_size == 0) { 97 key_size = avb_strlen(key); 98 } 99 100 data.key = key; 101 data.key_size = key_size; 102 103 if (avb_descriptor_foreach( 104 image_data, image_size, property_lookup_desc_foreach, &data) == 0) { 105 if (out_value_size != NULL) { 106 *out_value_size = data.ret_value_size; 107 } 108 return data.ret_value; 109 } 110 111 if (out_value_size != NULL) { 112 *out_value_size = 0; 113 } 114 return NULL; 115 } 116 117 bool avb_property_lookup_uint64(const uint8_t* image_data, 118 size_t image_size, 119 const char* key, 120 size_t key_size, 121 uint64_t* out_value) { 122 const char* value; 123 bool ret = false; 124 uint64_t parsed_val; 125 int base; 126 int n; 127 128 value = avb_property_lookup(image_data, image_size, key, key_size, NULL); 129 if (value == NULL) { 130 goto out; 131 } 132 133 base = 10; 134 if (avb_memcmp(value, "0x", 2) == 0) { 135 base = 16; 136 value += 2; 137 } 138 139 parsed_val = 0; 140 for (n = 0; value[n] != '\0'; n++) { 141 int c = value[n]; 142 int digit; 143 144 parsed_val *= base; 145 146 if (c >= '0' && c <= '9') { 147 digit = c - '0'; 148 } else if (base == 16 && c >= 'a' && c <= 'f') { 149 digit = c - 'a' + 10; 150 } else if (base == 16 && c >= 'A' && c <= 'F') { 151 digit = c - 'A' + 10; 152 } else { 153 avb_error("Invalid digit.\n"); 154 goto out; 155 } 156 157 parsed_val += digit; 158 } 159 160 ret = true; 161 if (out_value != NULL) { 162 *out_value = parsed_val; 163 } 164 165 out: 166 return ret; 167 } 168