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9a04f53a0f
It's easy to forget the responsibility of validating and safely copying kernel parameters in code that is far away from syscalls. ioctl's are one such example, and bugs there are just as dangerous as at the root syscall level. To avoid this case, utilize the AK::Userspace<T> template in the ioctl kernel interface so that implementors have no choice but to properly validate and copy ioctl pointer arguments.
129 lines
3.1 KiB
C++
129 lines
3.1 KiB
C++
/*
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* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#include <Kernel/Arch/x86/InterruptDisabler.h>
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#include <Kernel/Debug.h>
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#include <Kernel/Process.h>
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#include <Kernel/TTY/MasterPTY.h>
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#include <Kernel/TTY/PTYMultiplexer.h>
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#include <Kernel/TTY/SlavePTY.h>
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#include <LibC/errno_numbers.h>
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#include <LibC/signal_numbers.h>
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#include <LibC/sys/ioctl_numbers.h>
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namespace Kernel {
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MasterPTY::MasterPTY(unsigned index)
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: CharacterDevice(200, index)
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, m_slave(adopt_ref(*new SlavePTY(*this, index)))
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, m_index(index)
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{
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m_pts_name = String::formatted("/dev/pts/{}", m_index);
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auto process = Process::current();
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set_uid(process->uid());
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set_gid(process->gid());
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m_buffer.set_unblock_callback([this]() {
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if (m_slave)
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evaluate_block_conditions();
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});
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}
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MasterPTY::~MasterPTY()
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{
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dbgln_if(MASTERPTY_DEBUG, "~MasterPTY({})", m_index);
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PTYMultiplexer::the().notify_master_destroyed({}, m_index);
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}
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String MasterPTY::pts_name() const
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{
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return m_pts_name;
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}
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KResultOr<size_t> MasterPTY::read(FileDescription&, u64, UserOrKernelBuffer& buffer, size_t size)
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{
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if (!m_slave && m_buffer.is_empty())
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return 0;
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return m_buffer.read(buffer, size);
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}
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KResultOr<size_t> MasterPTY::write(FileDescription&, u64, const UserOrKernelBuffer& buffer, size_t size)
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{
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if (!m_slave)
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return EIO;
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m_slave->on_master_write(buffer, size);
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return size;
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}
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bool MasterPTY::can_read(const FileDescription&, size_t) const
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{
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if (!m_slave)
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return true;
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return !m_buffer.is_empty();
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}
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bool MasterPTY::can_write(const FileDescription&, size_t) const
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{
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return true;
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}
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void MasterPTY::notify_slave_closed(Badge<SlavePTY>)
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{
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dbgln_if(MASTERPTY_DEBUG, "MasterPTY({}): slave closed, my retains: {}, slave retains: {}", m_index, ref_count(), m_slave->ref_count());
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// +1 ref for my MasterPTY::m_slave
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// +1 ref for FileDescription::m_device
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if (m_slave->ref_count() == 2)
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m_slave = nullptr;
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}
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KResultOr<size_t> MasterPTY::on_slave_write(const UserOrKernelBuffer& data, size_t size)
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{
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if (m_closed)
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return EIO;
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return m_buffer.write(data, size);
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}
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bool MasterPTY::can_write_from_slave() const
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{
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if (m_closed)
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return true;
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return m_buffer.space_for_writing();
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}
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KResult MasterPTY::close()
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{
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InterruptDisabler disabler;
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// After the closing FileDescription dies, slave is the only thing keeping me alive.
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// From this point, let's consider ourselves closed.
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m_closed = true;
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if (m_slave)
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m_slave->hang_up();
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return KSuccess;
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}
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int MasterPTY::ioctl(FileDescription& description, unsigned request, Userspace<void*> arg)
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{
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REQUIRE_PROMISE(tty);
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if (!m_slave)
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return -EIO;
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if (request == TIOCSWINSZ || request == TIOCGPGRP)
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return m_slave->ioctl(description, request, arg);
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return -EINVAL;
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}
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String MasterPTY::absolute_path(const FileDescription&) const
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{
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return String::formatted("ptm:{}", m_pts_name);
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}
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String MasterPTY::device_name() const
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{
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return String::formatted("{}", minor());
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}
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}
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