avb_descriptor.c 4.1 KB

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  1. // SPDX-License-Identifier: MIT
  2. /*
  3. * Copyright (C) 2016 The Android Open Source Project
  4. */
  5. #include "avb_descriptor.h"
  6. #include "avb_util.h"
  7. #include "avb_vbmeta_image.h"
  8. #include <log.h>
  9. #include <malloc.h>
  10. bool avb_descriptor_validate_and_byteswap(const AvbDescriptor* src,
  11. AvbDescriptor* dest) {
  12. dest->tag = avb_be64toh(src->tag);
  13. dest->num_bytes_following = avb_be64toh(src->num_bytes_following);
  14. if ((dest->num_bytes_following & 0x07) != 0) {
  15. avb_error("Descriptor size is not divisible by 8.\n");
  16. return false;
  17. }
  18. return true;
  19. }
  20. bool avb_descriptor_foreach(const uint8_t* image_data,
  21. size_t image_size,
  22. AvbDescriptorForeachFunc foreach_func,
  23. void* user_data) {
  24. const AvbVBMetaImageHeader* header = NULL;
  25. bool ret = false;
  26. const uint8_t* image_end;
  27. const uint8_t* desc_start;
  28. const uint8_t* desc_end;
  29. const uint8_t* p;
  30. if (image_data == NULL) {
  31. avb_error("image_data is NULL\n.");
  32. goto out;
  33. }
  34. if (foreach_func == NULL) {
  35. avb_error("foreach_func is NULL\n.");
  36. goto out;
  37. }
  38. if (image_size < sizeof(AvbVBMetaImageHeader)) {
  39. avb_error("Length is smaller than header.\n");
  40. goto out;
  41. }
  42. /* Ensure magic is correct. */
  43. if (avb_memcmp(image_data, AVB_MAGIC, AVB_MAGIC_LEN) != 0) {
  44. avb_error("Magic is incorrect.\n");
  45. goto out;
  46. }
  47. /* Careful, not byteswapped - also ensure it's aligned properly. */
  48. avb_assert_aligned(image_data);
  49. header = (const AvbVBMetaImageHeader*)image_data;
  50. image_end = image_data + image_size;
  51. desc_start = image_data + sizeof(AvbVBMetaImageHeader) +
  52. avb_be64toh(header->authentication_data_block_size) +
  53. avb_be64toh(header->descriptors_offset);
  54. desc_end = desc_start + avb_be64toh(header->descriptors_size);
  55. if (desc_start < image_data || desc_start > image_end ||
  56. desc_end < image_data || desc_end > image_end || desc_end < desc_start) {
  57. avb_error("Descriptors not inside passed-in data.\n");
  58. goto out;
  59. }
  60. for (p = desc_start; p < desc_end;) {
  61. const AvbDescriptor* dh = (const AvbDescriptor*)p;
  62. avb_assert_aligned(dh);
  63. uint64_t nb_following = avb_be64toh(dh->num_bytes_following);
  64. uint64_t nb_total = 0;
  65. if (!avb_safe_add(&nb_total, sizeof(AvbDescriptor), nb_following)) {
  66. avb_error("Invalid descriptor length.\n");
  67. goto out;
  68. }
  69. if ((nb_total & 7) != 0) {
  70. avb_error("Invalid descriptor length.\n");
  71. goto out;
  72. }
  73. if (nb_total + p < desc_start || nb_total + p > desc_end) {
  74. avb_error("Invalid data in descriptors array.\n");
  75. goto out;
  76. }
  77. if (foreach_func(dh, user_data) == 0) {
  78. goto out;
  79. }
  80. if (!avb_safe_add_to((uint64_t*)(&p), nb_total)) {
  81. avb_error("Invalid descriptor length.\n");
  82. goto out;
  83. }
  84. }
  85. ret = true;
  86. out:
  87. return ret;
  88. }
  89. static bool count_descriptors(const AvbDescriptor* descriptor,
  90. void* user_data) {
  91. size_t* num_descriptors = user_data;
  92. *num_descriptors += 1;
  93. return true;
  94. }
  95. typedef struct {
  96. size_t descriptor_number;
  97. const AvbDescriptor** descriptors;
  98. } SetDescriptorData;
  99. static bool set_descriptors(const AvbDescriptor* descriptor, void* user_data) {
  100. SetDescriptorData* data = user_data;
  101. data->descriptors[data->descriptor_number++] = descriptor;
  102. return true;
  103. }
  104. const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data,
  105. size_t image_size,
  106. size_t* out_num_descriptors) {
  107. size_t num_descriptors = 0;
  108. SetDescriptorData data;
  109. avb_descriptor_foreach(
  110. image_data, image_size, count_descriptors, &num_descriptors);
  111. data.descriptor_number = 0;
  112. data.descriptors =
  113. avb_calloc(sizeof(const AvbDescriptor*) * (num_descriptors + 1));
  114. if (data.descriptors == NULL) {
  115. return NULL;
  116. }
  117. avb_descriptor_foreach(image_data, image_size, set_descriptors, &data);
  118. avb_assert(data.descriptor_number == num_descriptors);
  119. if (out_num_descriptors != NULL) {
  120. *out_num_descriptors = num_descriptors;
  121. }
  122. return data.descriptors;
  123. }