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- // SPDX-License-Identifier: MIT
- /*
- * Copyright (C) 2016 The Android Open Source Project
- */
- #include "avb_descriptor.h"
- #include "avb_util.h"
- #include "avb_vbmeta_image.h"
- bool avb_descriptor_validate_and_byteswap(const AvbDescriptor* src,
- AvbDescriptor* dest) {
- dest->tag = avb_be64toh(src->tag);
- dest->num_bytes_following = avb_be64toh(src->num_bytes_following);
- if ((dest->num_bytes_following & 0x07) != 0) {
- avb_error("Descriptor size is not divisible by 8.\n");
- return false;
- }
- return true;
- }
- bool avb_descriptor_foreach(const uint8_t* image_data,
- size_t image_size,
- AvbDescriptorForeachFunc foreach_func,
- void* user_data) {
- const AvbVBMetaImageHeader* header = NULL;
- bool ret = false;
- const uint8_t* image_end;
- const uint8_t* desc_start;
- const uint8_t* desc_end;
- const uint8_t* p;
- if (image_data == NULL) {
- avb_error("image_data is NULL\n.");
- goto out;
- }
- if (foreach_func == NULL) {
- avb_error("foreach_func is NULL\n.");
- goto out;
- }
- if (image_size < sizeof(AvbVBMetaImageHeader)) {
- avb_error("Length is smaller than header.\n");
- goto out;
- }
- /* Ensure magic is correct. */
- if (avb_memcmp(image_data, AVB_MAGIC, AVB_MAGIC_LEN) != 0) {
- avb_error("Magic is incorrect.\n");
- goto out;
- }
- /* Careful, not byteswapped - also ensure it's aligned properly. */
- avb_assert_aligned(image_data);
- header = (const AvbVBMetaImageHeader*)image_data;
- image_end = image_data + image_size;
- desc_start = image_data + sizeof(AvbVBMetaImageHeader) +
- avb_be64toh(header->authentication_data_block_size) +
- avb_be64toh(header->descriptors_offset);
- desc_end = desc_start + avb_be64toh(header->descriptors_size);
- if (desc_start < image_data || desc_start > image_end ||
- desc_end < image_data || desc_end > image_end || desc_end < desc_start) {
- avb_error("Descriptors not inside passed-in data.\n");
- goto out;
- }
- for (p = desc_start; p < desc_end;) {
- const AvbDescriptor* dh = (const AvbDescriptor*)p;
- avb_assert_aligned(dh);
- uint64_t nb_following = avb_be64toh(dh->num_bytes_following);
- uint64_t nb_total = 0;
- if (!avb_safe_add(&nb_total, sizeof(AvbDescriptor), nb_following)) {
- avb_error("Invalid descriptor length.\n");
- goto out;
- }
- if ((nb_total & 7) != 0) {
- avb_error("Invalid descriptor length.\n");
- goto out;
- }
- if (nb_total + p < desc_start || nb_total + p > desc_end) {
- avb_error("Invalid data in descriptors array.\n");
- goto out;
- }
- if (foreach_func(dh, user_data) == 0) {
- goto out;
- }
- if (!avb_safe_add_to((uint64_t*)(&p), nb_total)) {
- avb_error("Invalid descriptor length.\n");
- goto out;
- }
- }
- ret = true;
- out:
- return ret;
- }
- static bool count_descriptors(const AvbDescriptor* descriptor,
- void* user_data) {
- size_t* num_descriptors = user_data;
- *num_descriptors += 1;
- return true;
- }
- typedef struct {
- size_t descriptor_number;
- const AvbDescriptor** descriptors;
- } SetDescriptorData;
- static bool set_descriptors(const AvbDescriptor* descriptor, void* user_data) {
- SetDescriptorData* data = user_data;
- data->descriptors[data->descriptor_number++] = descriptor;
- return true;
- }
- const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data,
- size_t image_size,
- size_t* out_num_descriptors) {
- size_t num_descriptors = 0;
- SetDescriptorData data;
- avb_descriptor_foreach(
- image_data, image_size, count_descriptors, &num_descriptors);
- data.descriptor_number = 0;
- data.descriptors =
- avb_calloc(sizeof(const AvbDescriptor*) * (num_descriptors + 1));
- if (data.descriptors == NULL) {
- return NULL;
- }
- avb_descriptor_foreach(image_data, image_size, set_descriptors, &data);
- avb_assert(data.descriptor_number == num_descriptors);
- if (out_num_descriptors != NULL) {
- *out_num_descriptors = num_descriptors;
- }
- return data.descriptors;
- }
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