FileSystem: Route chown() and fchown() through VFS for access control.

Kernel/FileSystem/FileDescriptor.cpp

@@ -329,5 +329,5 @@ KResult FileDescriptor::chown(uid_t uid, gid_t gid)
 {
     if (!m_inode)
         return KResult(-EINVAL);
-    return m_inode->chown(uid, gid);
+    return VFS::the().chown(*m_inode, uid, gid);
 }

Kernel/FileSystem/VirtualFileSystem.cpp

@@ -402,14 +402,8 @@ KResult VFS::rename(StringView old_path, StringView new_path, Custody& base)
     return KSuccess;
 }
 
-KResult VFS::chown(StringView path, uid_t a_uid, gid_t a_gid, Custody& base)
+KResult VFS::chown(Inode& inode, uid_t a_uid, gid_t a_gid)
 {
-    auto custody_or_error = resolve_path(path, base);
-    if (custody_or_error.is_error())
-        return custody_or_error.error();
-    auto& custody = *custody_or_error.value();
-    auto& inode = custody.inode();
-
     if (inode.fs().is_readonly())
         return KResult(-EROFS);
 
@@ -436,6 +430,16 @@ KResult VFS::chown(StringView path, uid_t a_uid, gid_t a_gid, Custody& base)
     return inode.chown(new_uid, new_gid);
 }
 
+KResult VFS::chown(StringView path, uid_t a_uid, gid_t a_gid, Custody& base)
+{
+    auto custody_or_error = resolve_path(path, base);
+    if (custody_or_error.is_error())
+        return custody_or_error.error();
+    auto& custody = *custody_or_error.value();
+    auto& inode = custody.inode();
+    return chown(inode, a_uid, a_gid);
+}
+
 KResult VFS::link(StringView old_path, StringView new_path, Custody& base)
 {
     auto old_custody_or_error = resolve_path(old_path, base);

Kernel/FileSystem/VirtualFileSystem.h

@@ -70,6 +70,7 @@ public:
     KResult chmod(StringView path, mode_t, Custody& base);
     KResult fchmod(Inode&, mode_t);
     KResult chown(StringView path, uid_t, gid_t, Custody& base);
+    KResult chown(Inode&, uid_t, gid_t);
     KResult access(StringView path, int mode, Custody& base);
     KResult stat(StringView path, int options, Custody& base, struct stat&);
     KResult utime(StringView path, Custody& base, time_t atime, time_t mtime);