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