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