ladybird/Kernel/Syscalls/sendfd.cpp
Brian Gianforcaro 4b2651ddab Kernel: Track allocated FileDescriptionAndFlag elements in each Process
The way the Process::FileDescriptions::allocate() API works today means
that two callers who allocate back to back without associating a
FileDescription with the allocated FD, will receive the same FD and thus
one will stomp over the other.

Naively tracking which FileDescriptions are allocated and moving onto
the next would introduce other bugs however, as now if you "allocate"
a fd and then return early further down the control flow of the syscall
you would leak that fd.

This change modifies this behavior by tracking which descriptions are
allocated and then having an RAII type to "deallocate" the fd if the
association is not setup the end of it's scope.
2021-07-28 19:07:00 +02:00

68 lines
2 KiB
C++

/*
* Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
*
* SPDX-License-Identifier: BSD-2-Clause
*/
#include <Kernel/FileSystem/FileDescription.h>
#include <Kernel/Net/LocalSocket.h>
#include <Kernel/Process.h>
namespace Kernel {
KResultOr<FlatPtr> Process::sys$sendfd(int sockfd, int fd)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
REQUIRE_PROMISE(sendfd);
auto socket_description = fds().file_description(sockfd);
if (!socket_description)
return EBADF;
if (!socket_description->is_socket())
return ENOTSOCK;
auto& socket = *socket_description->socket();
if (!socket.is_local())
return EAFNOSUPPORT;
if (!socket.is_connected())
return ENOTCONN;
auto passing_descriptor = fds().file_description(fd);
if (!passing_descriptor)
return EBADF;
auto& local_socket = static_cast<LocalSocket&>(socket);
return local_socket.sendfd(*socket_description, *passing_descriptor);
}
KResultOr<FlatPtr> Process::sys$recvfd(int sockfd, int options)
{
VERIFY_PROCESS_BIG_LOCK_ACQUIRED(this)
REQUIRE_PROMISE(recvfd);
auto socket_description = fds().file_description(sockfd);
if (!socket_description)
return EBADF;
if (!socket_description->is_socket())
return ENOTSOCK;
auto& socket = *socket_description->socket();
if (!socket.is_local())
return EAFNOSUPPORT;
auto new_fd_or_error = m_fds.allocate();
if (new_fd_or_error.is_error())
return new_fd_or_error.error();
auto new_fd = new_fd_or_error.release_value();
auto& local_socket = static_cast<LocalSocket&>(socket);
auto received_descriptor_or_error = local_socket.recvfd(*socket_description);
if (received_descriptor_or_error.is_error())
return received_descriptor_or_error.error();
u32 fd_flags = 0;
if (options & O_CLOEXEC)
fd_flags |= FD_CLOEXEC;
m_fds[new_fd.fd].set(*received_descriptor_or_error.value(), fd_flags);
return new_fd.fd;
}
}