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serenity/Kernel/Devices/PS2MouseDevice.h
Tom c8d9f1b9c9 Kernel: Make copy_to/from_user safe and remove unnecessary checks
Since the CPU already does almost all necessary validation steps
for us, we don't really need to attempt to do this. Doing it
ourselves doesn't really work very reliably, because we'd have to
account for other processors modifying virtual memory, and we'd
have to account for e.g. pages not being able to be allocated
due to insufficient resources.

So change the copy_to/from_user (and associated helper functions)
to use the new safe_memcpy, which will return whether it succeeded
or not. The only manual validation step needed (which the CPU
can't perform for us) is making sure the pointers provided by user
mode aren't pointing to kernel mappings.

To make it easier to read/write from/to either kernel or user mode
data add the UserOrKernelBuffer helper class, which will internally
either use copy_from/to_user or directly memcpy, or pass the data
through directly using a temporary buffer on the stack.

Last but not least we need to keep syscall params trivial as we
need to copy them from/to user mode using copy_from/to_user.
2020-09-13 21:19:15 +02:00

85 lines
3.1 KiB
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/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include <AK/CircularQueue.h>
#include <Kernel/Devices/CharacterDevice.h>
#include <Kernel/Interrupts/IRQHandler.h>
#include <Kernel/API/MousePacket.h>
#include <Kernel/Random.h>
namespace Kernel {
class PS2MouseDevice final : public IRQHandler
, public CharacterDevice {
public:
PS2MouseDevice();
virtual ~PS2MouseDevice() override;
static void create();
static PS2MouseDevice& the();
// ^CharacterDevice
virtual bool can_read(const FileDescription&, size_t) const override;
virtual KResultOr<size_t> read(FileDescription&, size_t, UserOrKernelBuffer&, size_t) override;
virtual KResultOr<size_t> write(FileDescription&, size_t, const UserOrKernelBuffer&, size_t) override;
virtual bool can_write(const FileDescription&, size_t) const override { return true; }
virtual const char* purpose() const override { return class_name(); }
private:
// ^IRQHandler
void handle_vmmouse_absolute_pointer();
virtual void handle_irq(const RegisterState&) override;
// ^CharacterDevice
virtual const char* class_name() const override { return "PS2MouseDevice"; }
void initialize();
void check_device_presence();
void initialize_device();
void prepare_for_input();
void prepare_for_output();
void mouse_write(u8);
u8 mouse_read();
void wait_then_write(u8 port, u8 data);
u8 wait_then_read(u8 port);
void parse_data_packet();
void expect_ack();
void set_sample_rate(u8);
u8 get_device_id();
bool m_device_present { false };
CircularQueue<MousePacket, 100> m_queue;
u8 m_data_state { 0 };
u8 m_data[4];
bool m_has_wheel { false };
bool m_has_five_buttons { false };
EntropySource m_entropy_source;
};
}