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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.
79 lines
2.2 KiB
C++
79 lines
2.2 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/Debug.h>
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#include <Kernel/FileSystem/Custody.h>
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#include <Kernel/FileSystem/VirtualFileSystem.h>
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#include <Kernel/Process.h>
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namespace Kernel {
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ErrorOr<FlatPtr> Process::sys$open(Userspace<const Syscall::SC_open_params*> user_params)
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{
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VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
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auto params = TRY(copy_typed_from_user(user_params));
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int dirfd = params.dirfd;
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int options = params.options;
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u16 mode = params.mode;
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if (options & O_NOFOLLOW_NOERROR)
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return EINVAL;
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if (options & O_UNLINK_INTERNAL)
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return EINVAL;
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if (options & O_WRONLY)
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TRY(require_promise(Pledge::wpath));
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else if (options & O_RDONLY)
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TRY(require_promise(Pledge::rpath));
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if (options & O_CREAT)
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TRY(require_promise(Pledge::cpath));
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// Ignore everything except permission bits.
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mode &= 0777;
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auto path = TRY(get_syscall_path_argument(params.path));
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dbgln_if(IO_DEBUG, "sys$open(dirfd={}, path='{}', options={}, mode={})", dirfd, path->view(), options, mode);
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auto fd_allocation = TRY(m_fds.allocate());
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RefPtr<Custody> base;
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if (dirfd == AT_FDCWD) {
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base = current_directory();
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} else {
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auto base_description = TRY(fds().open_file_description(dirfd));
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if (!base_description->is_directory())
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return ENOTDIR;
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if (!base_description->custody())
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return EINVAL;
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base = base_description->custody();
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}
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auto description = TRY(VirtualFileSystem::the().open(path->view(), options, mode & ~umask(), *base));
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if (description->inode() && description->inode()->socket())
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return ENXIO;
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u32 fd_flags = (options & O_CLOEXEC) ? FD_CLOEXEC : 0;
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m_fds[fd_allocation.fd].set(move(description), fd_flags);
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return fd_allocation.fd;
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}
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ErrorOr<FlatPtr> Process::sys$close(int fd)
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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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auto description = TRY(fds().open_file_description(fd));
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auto result = description->close();
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m_fds[fd] = {};
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if (result.is_error())
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return result.release_error();
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return 0;
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}
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}
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