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/*
* Copyright 2014 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <keymaster/serializable.h>
#include <assert.h>
#include <keymaster/android_keymaster_utils.h>
namespace keymaster {
namespace {
/* Performs an overflow-checked bounds check */
bool buffer_bound_check(const uint8_t* buf, const uint8_t* end, size_t len) {
uintptr_t buf_next;
bool overflow_occurred = __builtin_add_overflow(__pval(buf), len, &buf_next);
return (!overflow_occurred) && (buf_next <= __pval(end));
}
} // namespace
uint8_t* append_to_buf(uint8_t* buf, const uint8_t* end, const void* data, size_t data_len) {
if (buffer_bound_check(buf, end, data_len)) {
memcpy(buf, data, data_len);
return buf + data_len;
} else {
return buf;
}
}
bool copy_from_buf(const uint8_t** buf_ptr, const uint8_t* end, void* dest, size_t size) {
if (buffer_bound_check(*buf_ptr, end, size)) {
memcpy(dest, *buf_ptr, size);
*buf_ptr += size;
return true;
} else {
return false;
}
}
bool copy_size_and_data_from_buf(const uint8_t** buf_ptr, const uint8_t* end, size_t* size,
UniquePtr<uint8_t[]>* dest) {
if (!copy_uint32_from_buf(buf_ptr, end, size)) return false;
if (*size == 0) {
dest->reset();
return true;
}
if (buffer_bound_check(*buf_ptr, end, *size)) {
dest->reset(new (std::nothrow) uint8_t[*size]);
if (!dest->get()) {
return false;
}
return copy_from_buf(buf_ptr, end, dest->get(), *size);
} else {
return false;
}
}
bool Buffer::reserve(size_t size) {
if (available_write() < size) {
size_t new_size = buffer_size_ + size - available_write();
uint8_t* new_buffer = new (std::nothrow) uint8_t[new_size];
if (!new_buffer) return false;
memcpy(new_buffer, buffer_.get() + read_position_, available_read());
memset_s(buffer_.get(), 0, buffer_size_);
buffer_.reset(new_buffer);
buffer_size_ = new_size;
write_position_ -= read_position_;
read_position_ = 0;
}
return true;
}
bool Buffer::Reinitialize(size_t size) {
Clear();
buffer_.reset(new (std::nothrow) uint8_t[size]);
if (!buffer_.get()) return false;
buffer_size_ = size;
read_position_ = 0;
write_position_ = 0;
return true;
}
bool Buffer::Reinitialize(const void* data, size_t data_len) {
Clear();
if (__pval(data) + data_len < __pval(data)) // Pointer wrap check
return false;
buffer_.reset(new (std::nothrow) uint8_t[data_len]);
if (!buffer_.get()) return false;
buffer_size_ = data_len;
memcpy(buffer_.get(), data, data_len);
read_position_ = 0;
write_position_ = buffer_size_;
return true;
}
size_t Buffer::available_write() const {
assert(buffer_size_ >= write_position_);
return buffer_size_ - write_position_;
}
size_t Buffer::available_read() const {
assert(buffer_size_ >= write_position_);
assert(write_position_ >= read_position_);
return write_position_ - read_position_;
}
bool Buffer::write(const uint8_t* src, size_t write_length) {
if (available_write() < write_length) return false;
memcpy(buffer_.get() + write_position_, src, write_length);
write_position_ += write_length;
return true;
}
bool Buffer::read(uint8_t* dest, size_t read_length) {
if (available_read() < read_length) return false;
memcpy(dest, buffer_.get() + read_position_, read_length);
read_position_ += read_length;
return true;
}
size_t Buffer::SerializedSize() const {
return sizeof(uint32_t) + available_read();
}
uint8_t* Buffer::Serialize(uint8_t* buf, const uint8_t* end) const {
return append_size_and_data_to_buf(buf, end, peek_read(), available_read());
}
bool Buffer::Deserialize(const uint8_t** buf_ptr, const uint8_t* end) {
Clear();
if (!copy_size_and_data_from_buf(buf_ptr, end, &buffer_size_, &buffer_)) {
buffer_.reset();
buffer_size_ = 0;
return false;
}
write_position_ = buffer_size_;
return true;
}
void Buffer::Clear() {
memset_s(buffer_.get(), 0, buffer_size_);
buffer_.reset();
read_position_ = 0;
write_position_ = 0;
buffer_size_ = 0;
}
} // namespace keymaster
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