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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy,
* modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#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;
uint64_t desc_offset = 0;
uint64_t desc_size = 0;
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;
}
/* The data is supposed to have been cryptographically verified at this point,
* This check is just adding defense in depth.
*/
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;) {
if (p + sizeof(AvbDescriptor) > desc_end) {
avb_error("Invalid descriptor length.\n");
goto out;
}
const AvbDescriptor* dh = (const AvbDescriptor*)p;
uint64_t nb_following;
uint64_t nb_total = 0;
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;
}