ladybird/Kernel/Syscalls/setpgid.cpp
Tom 538b985487 Kernel: Remove ProcessInspectionHandle and make Process RefCounted
By making the Process class RefCounted we don't really need
ProcessInspectionHandle anymore. This also fixes some race
conditions where a Process may be deleted while still being
used by ProcFS.

Also make sure to acquire the Process' lock when accessing
regions.

Last but not least, there's no reason why a thread can't be
scheduled while being inspected, though in practice it won't
happen anyway because the scheduler lock is held at the same
time.
2020-08-02 17:15:11 +02:00

131 lines
4.3 KiB
C++

/*
* 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.
*/
#include <Kernel/Process.h>
#include <Kernel/TTY/TTY.h>
namespace Kernel {
pid_t Process::sys$getsid(pid_t pid)
{
REQUIRE_PROMISE(proc);
if (pid == 0)
return m_sid;
ScopedSpinLock lock(g_processes_lock);
auto process = Process::from_pid(pid);
if (!process)
return -ESRCH;
if (m_sid != process->m_sid)
return -EPERM;
return process->m_sid;
}
pid_t Process::sys$setsid()
{
REQUIRE_PROMISE(proc);
InterruptDisabler disabler;
bool found_process_with_same_pgid_as_my_pid = false;
Process::for_each_in_pgrp(pid(), [&](auto&) {
found_process_with_same_pgid_as_my_pid = true;
return IterationDecision::Break;
});
if (found_process_with_same_pgid_as_my_pid)
return -EPERM;
m_sid = m_pid;
m_pgid = m_pid;
m_tty = nullptr;
return m_sid;
}
pid_t Process::sys$getpgid(pid_t pid)
{
REQUIRE_PROMISE(proc);
if (pid == 0)
return m_pgid;
ScopedSpinLock lock(g_processes_lock); // FIXME: Use a ProcessHandle
auto process = Process::from_pid(pid);
if (!process)
return -ESRCH;
return process->m_pgid;
}
pid_t Process::sys$getpgrp()
{
REQUIRE_PROMISE(stdio);
return m_pgid;
}
static pid_t get_sid_from_pgid(pid_t pgid)
{
ScopedSpinLock lock(g_processes_lock);
auto group_leader = Process::from_pid(pgid);
if (!group_leader)
return -1;
return group_leader->sid();
}
int Process::sys$setpgid(pid_t specified_pid, pid_t specified_pgid)
{
REQUIRE_PROMISE(proc);
ScopedSpinLock lock(g_processes_lock); // FIXME: Use a ProcessHandle
pid_t pid = specified_pid ? specified_pid : m_pid;
if (specified_pgid < 0) {
// The value of the pgid argument is less than 0, or is not a value supported by the implementation.
return -EINVAL;
}
auto process = Process::from_pid(pid);
if (!process)
return -ESRCH;
if (process != this && process->ppid() != m_pid) {
// The value of the pid argument does not match the process ID
// of the calling process or of a child process of the calling process.
return -ESRCH;
}
if (process->pid() == process->sid()) {
// The process indicated by the pid argument is a session leader.
return -EPERM;
}
if (process->ppid() == m_pid && process->sid() != sid()) {
// The value of the pid argument matches the process ID of a child
// process of the calling process and the child process is not in
// the same session as the calling process.
return -EPERM;
}
pid_t new_pgid = specified_pgid ? specified_pgid : process->m_pid;
pid_t current_sid = get_sid_from_pgid(process->m_pgid);
pid_t new_sid = get_sid_from_pgid(new_pgid);
if (current_sid != new_sid) {
// Can't move a process between sessions.
return -EPERM;
}
// FIXME: There are more EPERM conditions to check for here..
process->m_pgid = new_pgid;
return 0;
}
}