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
avb_descriptor_validate_and_byteswap(const AvbDescriptor * src,AvbDescriptor * dest)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
avb_descriptor_foreach(const uint8_t * image_data,size_t image_size,AvbDescriptorForeachFunc foreach_func,void * user_data)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
count_descriptors(const AvbDescriptor * descriptor,void * user_data)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
set_descriptors(const AvbDescriptor * descriptor,void * user_data)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
avb_descriptor_get_all(const uint8_t * image_data,size_t image_size,size_t * out_num_descriptors)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