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https://github.com/SerenityOS/serenity
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54b9a4ec1e
Previously we would crash the process immediately when a promise violation was found during a syscall. This is error prone, as we don't unwind the stack. This means that in certain cases we can leak resources, like an OwnPtr / RefPtr tracked on the stack. Or even leak a lock acquired in a ScopeLockLocker. To remedy this situation we move the promise violation handling to the syscall handler, right before we return to user space. This allows the code to follow the normal unwind path, and grantees there is no longer any cleanup that needs to occur. The Process::require_promise() and Process::require_no_promises() functions were modified to return ErrorOr<void> so we enforce that the errors are always propagated by the caller.
126 lines
3.9 KiB
C++
126 lines
3.9 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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ErrorOr<FlatPtr> Process::sys$getsid(pid_t pid)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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TRY(require_promise(Pledge::proc));
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if (pid == 0)
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return sid().value();
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auto process = Process::from_pid(pid);
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if (!process)
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return ESRCH;
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if (sid() != process->sid())
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return EPERM;
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return process->sid().value();
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}
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ErrorOr<FlatPtr> Process::sys$setsid()
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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TRY(require_promise(Pledge::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 = TRY(ProcessGroup::try_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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ErrorOr<FlatPtr> Process::sys$getpgid(pid_t pid)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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TRY(require_promise(Pledge::proc));
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if (pid == 0)
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return pgid().value();
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auto process = Process::from_pid(pid);
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if (!process)
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return ESRCH;
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return process->pgid().value();
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}
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ErrorOr<FlatPtr> Process::sys$getpgrp()
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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TRY(require_promise(Pledge::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$setsid() uses the wrong locking mechanism.
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SessionID sid { -1 };
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Process::for_each_in_pgrp(pgid, [&](auto& process) {
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sid = process.sid();
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return IterationDecision::Break;
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});
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return sid;
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}
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ErrorOr<FlatPtr> Process::sys$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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TRY(require_promise(Pledge::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 = TRY(ProcessGroup::try_find_or_create(new_pgid));
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return 0;
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}
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}
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