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 "avb_property_descriptor.h"
26 #include "avb_util.h"
27
avb_property_descriptor_validate_and_byteswap(const AvbPropertyDescriptor * src,AvbPropertyDescriptor * dest)28 bool avb_property_descriptor_validate_and_byteswap(
29 const AvbPropertyDescriptor* src, AvbPropertyDescriptor* dest) {
30 uint64_t expected_size;
31
32 avb_memcpy(dest, src, sizeof(AvbPropertyDescriptor));
33
34 if (!avb_descriptor_validate_and_byteswap((const AvbDescriptor*)src,
35 (AvbDescriptor*)dest))
36 return false;
37
38 if (dest->parent_descriptor.tag != AVB_DESCRIPTOR_TAG_PROPERTY) {
39 avb_error("Invalid tag for property descriptor.\n");
40 return false;
41 }
42
43 dest->key_num_bytes = avb_be64toh(dest->key_num_bytes);
44 dest->value_num_bytes = avb_be64toh(dest->value_num_bytes);
45
46 /* Check that key and value are fully contained. */
47 expected_size = sizeof(AvbPropertyDescriptor) - sizeof(AvbDescriptor) + 2;
48 if (!avb_safe_add_to(&expected_size, dest->key_num_bytes) ||
49 !avb_safe_add_to(&expected_size, dest->value_num_bytes)) {
50 avb_error("Overflow while adding up sizes.\n");
51 return false;
52 }
53 if (expected_size > dest->parent_descriptor.num_bytes_following) {
54 avb_error("Descriptor payload size overflow.\n");
55 return false;
56 }
57
58 return true;
59 }
60
61 typedef struct {
62 const char* key;
63 size_t key_size;
64 const char* ret_value;
65 size_t ret_value_size;
66 } PropertyIteratorData;
67
property_lookup_desc_foreach(const AvbDescriptor * header,void * user_data)68 static bool property_lookup_desc_foreach(const AvbDescriptor* header,
69 void* user_data) {
70 PropertyIteratorData* data = (PropertyIteratorData*)user_data;
71 AvbPropertyDescriptor prop_desc;
72 const uint8_t* p;
73 bool ret = true;
74
75 if (header->tag != AVB_DESCRIPTOR_TAG_PROPERTY) {
76 goto out;
77 }
78
79 if (!avb_property_descriptor_validate_and_byteswap(
80 (const AvbPropertyDescriptor*)header, &prop_desc)) {
81 goto out;
82 }
83
84 p = (const uint8_t*)header;
85 if (p[sizeof(AvbPropertyDescriptor) + prop_desc.key_num_bytes] != 0) {
86 avb_error("No terminating NUL byte in key.\n");
87 goto out;
88 }
89
90 if (data->key_size == prop_desc.key_num_bytes) {
91 if (avb_memcmp(p + sizeof(AvbPropertyDescriptor),
92 data->key,
93 data->key_size) == 0) {
94 data->ret_value = (const char*)(p + sizeof(AvbPropertyDescriptor) +
95 prop_desc.key_num_bytes + 1);
96 data->ret_value_size = prop_desc.value_num_bytes;
97 /* Stop iterating. */
98 ret = false;
99 goto out;
100 }
101 }
102
103 out:
104 return ret;
105 }
106
avb_property_lookup(const uint8_t * image_data,size_t image_size,const char * key,size_t key_size,size_t * out_value_size)107 const char* avb_property_lookup(const uint8_t* image_data,
108 size_t image_size,
109 const char* key,
110 size_t key_size,
111 size_t* out_value_size) {
112 PropertyIteratorData data;
113
114 if (key_size == 0) {
115 key_size = avb_strlen(key);
116 }
117
118 data.key = key;
119 data.key_size = key_size;
120
121 if (avb_descriptor_foreach(
122 image_data, image_size, property_lookup_desc_foreach, &data) == 0) {
123 if (out_value_size != NULL) {
124 *out_value_size = data.ret_value_size;
125 }
126 return data.ret_value;
127 }
128
129 if (out_value_size != NULL) {
130 *out_value_size = 0;
131 }
132 return NULL;
133 }
134
avb_property_lookup_uint64(const uint8_t * image_data,size_t image_size,const char * key,size_t key_size,uint64_t * out_value)135 bool avb_property_lookup_uint64(const uint8_t* image_data,
136 size_t image_size,
137 const char* key,
138 size_t key_size,
139 uint64_t* out_value) {
140 const char* value;
141 bool ret = false;
142 uint64_t parsed_val;
143 int base;
144 int n;
145
146 value = avb_property_lookup(image_data, image_size, key, key_size, NULL);
147 if (value == NULL) {
148 goto out;
149 }
150
151 base = 10;
152 if (avb_memcmp(value, "0x", 2) == 0) {
153 base = 16;
154 value += 2;
155 }
156
157 parsed_val = 0;
158 for (n = 0; value[n] != '\0'; n++) {
159 int c = value[n];
160 int digit;
161
162 parsed_val *= base;
163
164 if (c >= '0' && c <= '9') {
165 digit = c - '0';
166 } else if (base == 16 && c >= 'a' && c <= 'f') {
167 digit = c - 'a' + 10;
168 } else if (base == 16 && c >= 'A' && c <= 'F') {
169 digit = c - 'A' + 10;
170 } else {
171 avb_error("Invalid digit.\n");
172 goto out;
173 }
174
175 parsed_val += digit;
176 }
177
178 ret = true;
179 if (out_value != NULL) {
180 *out_value = parsed_val;
181 }
182
183 out:
184 return ret;
185 }
186