mirror of
https://github.com/RGBCube/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.
74 lines
1.8 KiB
C++
74 lines
1.8 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/Process.h>
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namespace Kernel {
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ErrorOr<FlatPtr> Process::sys$yield()
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{
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VERIFY_NO_PROCESS_BIG_LOCK(this);
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TRY(require_promise(Pledge::stdio));
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Thread::current()->yield_without_releasing_big_lock();
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return 0;
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}
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ErrorOr<FlatPtr> Process::sys$sched_setparam(int pid, Userspace<const struct sched_param*> user_param)
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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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auto param = TRY(copy_typed_from_user(user_param));
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if (param.sched_priority < THREAD_PRIORITY_MIN || param.sched_priority > THREAD_PRIORITY_MAX)
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return EINVAL;
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auto* peer = Thread::current();
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SpinlockLocker lock(g_scheduler_lock);
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if (pid != 0)
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peer = Thread::from_tid(pid);
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if (!peer)
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return ESRCH;
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if (!is_superuser() && euid() != peer->process().uid() && uid() != peer->process().uid())
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return EPERM;
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peer->set_priority((u32)param.sched_priority);
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return 0;
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}
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ErrorOr<FlatPtr> Process::sys$sched_getparam(pid_t pid, Userspace<struct sched_param*> user_param)
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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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int priority;
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{
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auto* peer = Thread::current();
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SpinlockLocker lock(g_scheduler_lock);
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if (pid != 0) {
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// FIXME: PID/TID BUG
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// The entire process is supposed to be affected.
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peer = Thread::from_tid(pid);
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}
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if (!peer)
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return ESRCH;
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if (!is_superuser() && euid() != peer->process().uid() && uid() != peer->process().uid())
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return EPERM;
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priority = (int)peer->priority();
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}
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struct sched_param param {
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priority
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};
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TRY(copy_to_user(user_param, ¶m));
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return 0;
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}
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}
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