David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2016 The Android Open Source Project |
| 3 | * |
David Zeuthen | c612e2e | 2016-09-16 16:44:08 -0400 | [diff] [blame] | 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: |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 11 | * |
David Zeuthen | c612e2e | 2016-09-16 16:44:08 -0400 | [diff] [blame] | 12 | * The above copyright notice and this permission notice shall be |
| 13 | * included in all copies or substantial portions of the Software. |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 14 | * |
David Zeuthen | c612e2e | 2016-09-16 16:44:08 -0400 | [diff] [blame] | 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. |
David Zeuthen | 21e9526 | 2016-07-27 17:58:40 -0400 | [diff] [blame] | 23 | */ |
| 24 | |
| 25 | #include "avb_descriptor.h" |
| 26 | #include "avb_util.h" |
| 27 | #include "avb_vbmeta_image.h" |
| 28 | |
| 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 | |
| 41 | bool avb_descriptor_foreach(const uint8_t* image_data, size_t image_size, |
| 42 | AvbDescriptorForeachFunc foreach_func, |
| 43 | void* user_data) { |
| 44 | const AvbVBMetaImageHeader* header = NULL; |
| 45 | bool ret = false; |
| 46 | const uint8_t* image_end; |
| 47 | const uint8_t* desc_start; |
| 48 | const uint8_t* desc_end; |
| 49 | const uint8_t* p; |
| 50 | |
| 51 | if (image_data == NULL) { |
| 52 | avb_error("image_data is NULL\n."); |
| 53 | goto out; |
| 54 | } |
| 55 | |
| 56 | if (foreach_func == NULL) { |
| 57 | avb_error("foreach_func is NULL\n."); |
| 58 | goto out; |
| 59 | } |
| 60 | |
| 61 | if (image_size < sizeof(AvbVBMetaImageHeader)) { |
| 62 | avb_error("Length is smaller than header.\n"); |
| 63 | goto out; |
| 64 | } |
| 65 | |
| 66 | /* Ensure magic is correct. */ |
| 67 | if (avb_memcmp(image_data, AVB_MAGIC, AVB_MAGIC_LEN) != 0) { |
| 68 | avb_error("Magic is incorrect.\n"); |
| 69 | goto out; |
| 70 | } |
| 71 | |
| 72 | /* Careful, not byteswapped - also ensure it's aligned properly. */ |
| 73 | avb_assert_word_aligned(image_data); |
| 74 | header = (const AvbVBMetaImageHeader*)image_data; |
| 75 | image_end = image_data + image_size; |
| 76 | |
| 77 | desc_start = image_data + sizeof(AvbVBMetaImageHeader) + |
| 78 | avb_be64toh(header->authentication_data_block_size) + |
| 79 | avb_be64toh(header->descriptors_offset); |
| 80 | |
| 81 | desc_end = desc_start + avb_be64toh(header->descriptors_size); |
| 82 | |
| 83 | if (desc_start < image_data || desc_start > image_end || |
| 84 | desc_end < image_data || desc_end > image_end || desc_end < desc_start) { |
| 85 | avb_error("Descriptors not inside passed-in data.\n"); |
| 86 | goto out; |
| 87 | } |
| 88 | |
| 89 | for (p = desc_start; p < desc_end;) { |
| 90 | const AvbDescriptor* dh = (const AvbDescriptor*)p; |
| 91 | avb_assert_word_aligned(dh); |
| 92 | uint64_t nb_following = avb_be64toh(dh->num_bytes_following); |
| 93 | uint64_t nb_total = sizeof(AvbDescriptor) + nb_following; |
| 94 | |
| 95 | if ((nb_total & 7) != 0) { |
| 96 | avb_error("Invalid descriptor length.\n"); |
| 97 | goto out; |
| 98 | } |
| 99 | |
| 100 | if (nb_total + p < desc_start || nb_total + p > desc_end) { |
| 101 | avb_error("Invalid data in descriptors array.\n"); |
| 102 | goto out; |
| 103 | } |
| 104 | |
| 105 | if (foreach_func(dh, user_data) == 0) { |
| 106 | goto out; |
| 107 | } |
| 108 | |
| 109 | p += nb_total; |
| 110 | } |
| 111 | |
| 112 | ret = true; |
| 113 | |
| 114 | out: |
| 115 | return ret; |
| 116 | } |
| 117 | |
| 118 | static bool count_descriptors(const AvbDescriptor* descriptor, |
| 119 | void* user_data) { |
| 120 | size_t* num_descriptors = user_data; |
| 121 | *num_descriptors += 1; |
| 122 | return true; |
| 123 | } |
| 124 | |
| 125 | typedef struct { |
| 126 | size_t descriptor_number; |
| 127 | const AvbDescriptor** descriptors; |
| 128 | } SetDescriptorData; |
| 129 | |
| 130 | static bool set_descriptors(const AvbDescriptor* descriptor, void* user_data) { |
| 131 | SetDescriptorData* data = user_data; |
| 132 | data->descriptors[data->descriptor_number++] = descriptor; |
| 133 | return true; |
| 134 | } |
| 135 | |
| 136 | const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data, |
| 137 | size_t image_size, |
| 138 | size_t* out_num_descriptors) { |
| 139 | size_t num_descriptors = 0; |
| 140 | SetDescriptorData data; |
| 141 | |
| 142 | avb_descriptor_foreach(image_data, image_size, count_descriptors, |
| 143 | &num_descriptors); |
| 144 | |
| 145 | data.descriptor_number = 0; |
| 146 | data.descriptors = |
| 147 | avb_calloc(sizeof(const AvbDescriptor*) * (num_descriptors + 1)); |
| 148 | if (data.descriptors == NULL) { |
| 149 | return NULL; |
| 150 | } |
| 151 | avb_descriptor_foreach(image_data, image_size, set_descriptors, &data); |
| 152 | avb_assert(data.descriptor_number == num_descriptors); |
| 153 | |
| 154 | if (out_num_descriptors != NULL) { |
| 155 | *out_num_descriptors = num_descriptors; |
| 156 | } |
| 157 | |
| 158 | return data.descriptors; |
| 159 | } |