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01b79910b3
The compiler can re-order the structure (class) members if that's necessary, so if we make Process to inherit from ProcFSExposedComponent, even if the declaration is to inherit first from ProcessBase, then from ProcFSExposedComponent and last from Weakable<Process>, the members of class ProcFSExposedComponent (including the Ref-counted parts) are the first members of the Process class. This problem made it impossible to safely use the current toggling method with the write-protection bit on the ProcessBase members, so instead of inheriting from it, we make its members the last ones in the Process class so we can safely locate and modify the corresponding page write protection bit of these values. We make sure that the Process class doesn't expand beyond 8192 bytes and the protected values are always aligned on a page boundary.
128 lines
3.8 KiB
C++
128 lines
3.8 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/Process.h>
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#include <Kernel/TTY/TTY.h>
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namespace Kernel {
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KResultOr<FlatPtr> Process::sys$getsid(pid_t pid)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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REQUIRE_PROMISE(proc);
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if (pid == 0)
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return sid().value();
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auto process = Process::from_pid(pid);
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if (!process)
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return ESRCH;
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if (sid() != process->sid())
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return EPERM;
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return process->sid().value();
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}
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KResultOr<FlatPtr> Process::sys$setsid()
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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REQUIRE_PROMISE(proc);
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InterruptDisabler disabler;
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bool found_process_with_same_pgid_as_my_pid = false;
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Process::for_each_in_pgrp(pid().value(), [&](auto&) {
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found_process_with_same_pgid_as_my_pid = true;
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return IterationDecision::Break;
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});
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if (found_process_with_same_pgid_as_my_pid)
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return EPERM;
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// Create a new Session and a new ProcessGroup.
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m_pg = ProcessGroup::create(ProcessGroupID(pid().value()));
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m_tty = nullptr;
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ProtectedDataMutationScope scope { *this };
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m_protected_values.sid = pid().value();
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return sid().value();
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}
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KResultOr<FlatPtr> Process::sys$getpgid(pid_t pid)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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REQUIRE_PROMISE(proc);
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if (pid == 0)
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return pgid().value();
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auto process = Process::from_pid(pid);
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if (!process)
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return ESRCH;
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return process->pgid().value();
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}
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KResultOr<FlatPtr> Process::sys$getpgrp()
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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REQUIRE_PROMISE(stdio);
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return pgid().value();
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}
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SessionID Process::get_sid_from_pgid(ProcessGroupID pgid)
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{
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// FIXME: This xor sys$setsid() uses the wrong locking mechanism.
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SessionID sid { -1 };
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Process::for_each_in_pgrp(pgid, [&](auto& process) {
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sid = process.sid();
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return IterationDecision::Break;
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});
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return sid;
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}
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KResultOr<FlatPtr> Process::sys$setpgid(pid_t specified_pid, pid_t specified_pgid)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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REQUIRE_PROMISE(proc);
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ProcessID pid = specified_pid ? ProcessID(specified_pid) : this->pid();
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if (specified_pgid < 0) {
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// The value of the pgid argument is less than 0, or is not a value supported by the implementation.
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return EINVAL;
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}
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auto process = Process::from_pid(pid);
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if (!process)
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return ESRCH;
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if (process != this && process->ppid() != this->pid()) {
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// The value of the pid argument does not match the process ID
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// of the calling process or of a child process of the calling process.
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return ESRCH;
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}
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if (process->is_session_leader()) {
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// The process indicated by the pid argument is a session leader.
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return EPERM;
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}
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if (process->ppid() == this->pid() && process->sid() != sid()) {
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// The value of the pid argument matches the process ID of a child
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// process of the calling process and the child process is not in
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// the same session as the calling process.
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return EPERM;
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}
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ProcessGroupID new_pgid = specified_pgid ? ProcessGroupID(specified_pgid) : process->pid().value();
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SessionID current_sid = sid();
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SessionID new_sid = get_sid_from_pgid(new_pgid);
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if (new_sid != -1 && current_sid != new_sid) {
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// Can't move a process between sessions.
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return EPERM;
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}
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if (new_sid == -1 && new_pgid != process->pid().value()) {
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// The value of the pgid argument is valid, but is not
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// the calling pid, and is not an existing process group.
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return EPERM;
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}
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// FIXME: There are more EPERM conditions to check for here..
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process->m_pg = ProcessGroup::find_or_create(new_pgid);
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if (!process->m_pg) {
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return ENOMEM;
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}
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return 0;
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}
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}
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