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_descriptor.h"
26#include "avb_util.h"
27#include "avb_vbmeta_image.h"
28
29bool 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
41bool 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 = sizeof(AvbDescriptor) + nb_following;
95
96    if ((nb_total & 7) != 0) {
97      avb_error("Invalid descriptor length.\n");
98      goto out;
99    }
100
101    if (nb_total + p < desc_start || nb_total + p > desc_end) {
102      avb_error("Invalid data in descriptors array.\n");
103      goto out;
104    }
105
106    if (foreach_func(dh, user_data) == 0) {
107      goto out;
108    }
109
110    p += nb_total;
111  }
112
113  ret = true;
114
115out:
116  return ret;
117}
118
119static bool count_descriptors(const AvbDescriptor* descriptor,
120                              void* user_data) {
121  size_t* num_descriptors = user_data;
122  *num_descriptors += 1;
123  return true;
124}
125
126typedef struct {
127  size_t descriptor_number;
128  const AvbDescriptor** descriptors;
129} SetDescriptorData;
130
131static bool set_descriptors(const AvbDescriptor* descriptor, void* user_data) {
132  SetDescriptorData* data = user_data;
133  data->descriptors[data->descriptor_number++] = descriptor;
134  return true;
135}
136
137const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data,
138                                             size_t image_size,
139                                             size_t* out_num_descriptors) {
140  size_t num_descriptors = 0;
141  SetDescriptorData data;
142
143  avb_descriptor_foreach(
144      image_data, image_size, count_descriptors, &num_descriptors);
145
146  data.descriptor_number = 0;
147  data.descriptors =
148      avb_calloc(sizeof(const AvbDescriptor*) * (num_descriptors + 1));
149  if (data.descriptors == NULL) {
150    return NULL;
151  }
152  avb_descriptor_foreach(image_data, image_size, set_descriptors, &data);
153  avb_assert(data.descriptor_number == num_descriptors);
154
155  if (out_num_descriptors != NULL) {
156    *out_num_descriptors = num_descriptors;
157  }
158
159  return data.descriptors;
160}
161