From cda56f8049df93a659b228088d2f3d1387558116 Mon Sep 17 00:00:00 2001
From: Andreas Kling <kling@serenityos.org>
Date: Mon, 7 Feb 2022 12:57:57 +0100
Subject: [PATCH] Kernel: Robustify and rename Inode bound socket API

Rename the bound socket accessor from socket() to bound_socket().
Also return RefPtr<LocalSocket> instead of a raw pointer, to make it
harder for callers to mess up.
---
 Kernel/FileSystem/Inode.cpp | 13 +++++++++----
 Kernel/FileSystem/Inode.h   |  5 ++---
 Kernel/Net/LocalSocket.cpp  |  5 +++--
 Kernel/Syscalls/open.cpp    |  3 ++-
 4 files changed, 16 insertions(+), 10 deletions(-)

diff --git a/Kernel/FileSystem/Inode.cpp b/Kernel/FileSystem/Inode.cpp
index 1b8a606c9e..a8822a1e23 100644
--- a/Kernel/FileSystem/Inode.cpp
+++ b/Kernel/FileSystem/Inode.cpp
@@ -136,21 +136,26 @@ void Inode::set_shared_vmobject(Memory::SharedInodeVMObject& vmobject)
     m_shared_vmobject = vmobject;
 }
 
+RefPtr<LocalSocket> Inode::bound_socket() const
+{
+    return m_bound_socket;
+}
+
 bool Inode::bind_socket(LocalSocket& socket)
 {
     MutexLocker locker(m_inode_lock);
-    if (m_socket)
+    if (m_bound_socket)
         return false;
-    m_socket = socket;
+    m_bound_socket = socket;
     return true;
 }
 
 bool Inode::unbind_socket()
 {
     MutexLocker locker(m_inode_lock);
-    if (!m_socket)
+    if (!m_bound_socket)
         return false;
-    m_socket = nullptr;
+    m_bound_socket = nullptr;
     return true;
 }
 
diff --git a/Kernel/FileSystem/Inode.h b/Kernel/FileSystem/Inode.h
index 775e4ad020..7351e892e2 100644
--- a/Kernel/FileSystem/Inode.h
+++ b/Kernel/FileSystem/Inode.h
@@ -66,8 +66,7 @@ public:
 
     virtual ErrorOr<int> get_block_address(int) { return ENOTSUP; }
 
-    LocalSocket* socket() { return m_socket.ptr(); }
-    const LocalSocket* socket() const { return m_socket.ptr(); }
+    RefPtr<LocalSocket> bound_socket() const;
     bool bind_socket(LocalSocket&);
     bool unbind_socket();
 
@@ -117,7 +116,7 @@ private:
     FileSystem& m_file_system;
     InodeIndex m_index { 0 };
     WeakPtr<Memory::SharedInodeVMObject> m_shared_vmobject;
-    RefPtr<LocalSocket> m_socket;
+    RefPtr<LocalSocket> m_bound_socket;
     SpinlockProtected<HashTable<InodeWatcher*>> m_watchers;
     bool m_metadata_dirty { false };
     RefPtr<FIFO> m_fifo;
diff --git a/Kernel/Net/LocalSocket.cpp b/Kernel/Net/LocalSocket.cpp
index 14b84ae98c..de46196624 100644
--- a/Kernel/Net/LocalSocket.cpp
+++ b/Kernel/Net/LocalSocket.cpp
@@ -174,7 +174,9 @@ ErrorOr<void> LocalSocket::connect(OpenFileDescription& description, Userspace<c
     m_inode = inode;
 
     VERIFY(inode);
-    if (!inode->socket())
+
+    auto peer = inode->bound_socket();
+    if (!peer)
         return set_so_error(ECONNREFUSED);
 
     m_path = move(path);
@@ -182,7 +184,6 @@ ErrorOr<void> LocalSocket::connect(OpenFileDescription& description, Userspace<c
     VERIFY(m_connect_side_fd == &description);
     set_connect_side_role(Role::Connecting);
 
-    auto peer = file->inode()->socket();
     auto result = peer->queue_connection_from(*this);
     if (result.is_error()) {
         set_connect_side_role(Role::None);
diff --git a/Kernel/Syscalls/open.cpp b/Kernel/Syscalls/open.cpp
index 8943ad8086..34b1754d3b 100644
--- a/Kernel/Syscalls/open.cpp
+++ b/Kernel/Syscalls/open.cpp
@@ -7,6 +7,7 @@
 #include <Kernel/Debug.h>
 #include <Kernel/FileSystem/Custody.h>
 #include <Kernel/FileSystem/VirtualFileSystem.h>
+#include <Kernel/Net/LocalSocket.h>
 #include <Kernel/Process.h>
 
 namespace Kernel {
@@ -56,7 +57,7 @@ ErrorOr<FlatPtr> Process::sys$open(Userspace<const Syscall::SC_open_params*> use
 
     auto description = TRY(VirtualFileSystem::the().open(path->view(), options, mode & ~umask(), *base));
 
-    if (description->inode() && description->inode()->socket())
+    if (description->inode() && description->inode()->bound_socket())
         return ENXIO;
 
     return m_fds.with_exclusive([&](auto& fds) -> ErrorOr<FlatPtr> {