// 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"
#include <log.h>
#include <malloc.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;
    uint64_t desc_offset = 0;
    uint64_t desc_size = 0;

    if (!image_data) {
        avb_error("image_data is NULL\n.");
        goto out;
    }

    if (!foreach_func) {
        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;

    /* Since the data is supposed to have been cryptographically verified at this
     * point, being overflow-safe is just for defense.
     * The following lines are overflow-safe version of:
     * desc_offset = sizeof(AvbVBMetaImageHeader) +
     *               avb_be64toh(header->authentication_data_block_size)) +
     *               avb_be64toh(header->descriptors_offset)
     */
    if (!avb_safe_add(&desc_offset,
            sizeof(AvbVBMetaImageHeader),
            avb_be64toh(header->authentication_data_block_size))) {
        avb_error("Invalid authentication data block size.\n");
        goto out;
    }
    if (!avb_safe_add_to(&desc_offset, avb_be64toh(header->descriptors_offset))) {
        avb_error("Invalid descriptors offset.\n");
        goto out;
    }

    if (desc_offset > (uint64_t)(image_end - image_data)) {
        avb_error("Descriptors not inside passed-in data.\n");
        goto out;
    }

    desc_start = image_data + desc_offset;

    desc_size = avb_be64toh(header->descriptors_size);
    if (desc_size > (uint64_t)(image_end - desc_start)) {
        avb_error("Descriptors not inside passed-in data.\n");
        goto out;
    }

    desc_end = desc_start + desc_size;

    for (p = desc_start; p < desc_end;) {
        uint64_t nb_following;
        uint64_t nb_total = 0;

        const AvbDescriptor *dh;

        if (sizeof(AvbDescriptor) > (size_t)(desc_end - p)) {
            avb_error("Invalid descriptor length.\n");
            goto out;
        }

        dh = (const AvbDescriptor *)p;
        avb_assert_aligned(dh);
        nb_following = avb_be64toh(dh->num_bytes_following);

        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 > (uint64_t)(desc_end - p)) {
            avb_error("Invalid data in descriptors array.\n");
            goto out;
        }

        if (foreach_func(dh, user_data) == 0)
            goto out;

        p += nb_total;
    }

    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;
}