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
28bool 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
61typedef struct {
62  const char* key;
63  size_t key_size;
64  const char* ret_value;
65  size_t ret_value_size;
66} PropertyIteratorData;
67
68static 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
103out:
104  return ret;
105}
106
107const 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
135bool 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
183out:
184  return ret;
185}
186