在我的 Ubuntu 服务器上安装 samba 后，我收到警告（来自 samba 安装程序），警告我为我的/etc和/usr文件夹设置了奇怪的所有权和权限。我检查了一下，确实/etc和/usr目前由用户“5640”和组“13023”拥有。我的系统上不存在这个用户和那个组（检查了/etc/passwd和/etc/group）。
我的根文件夹如下：
drwxr-xr-x 24 root root 4096 Jun 26 06:54 .
drwxr-xr-x 24 root root 4096 Jun 26 06:54 ..
drwxr-xr-x 2 root root 4096 May 20 08:27 bin
drwxr-xr-x 4 root root 4096 Jun 27 06:54 boot
drwxr-xr-x 2 root root 4096 Nov 20 2019 cdrom
drwxr-xr-x 20 root root 4020 Jun 18 13:43 dev
drwxrwxr-x 159 5640 13023 12288 Jun 30 12:36 etc
drwxr-xr-x 14 root root 4096 May 29 11:34 home
lrwxrwxrwx 1 root root 34 Jun 26 06:54 initrd.img -> boot/initrd.img-4.15.0-108-generic
lrwxrwxrwx 1 root root 34 Jun 26 06:54 initrd.img.old -> boot/initrd.img-4.15.0-106-generic
-rw-r--r-- 1 root root 8114876 Nov 25 2019 jkweb.a
drwxr-xr-x 25 root root 4096 Apr 8 16:58 lib
drwxr-xr-x 2 root root 4096 Aug 5 2019 lib64
drwx------ 2 root root 16384 Nov 20 2019 lost+found
drwxr-xr-x 2 root root 4096 Aug 5 2019 media
drwxr-xr-x 2 root root 4096 Aug 5 2019 mnt
drwxr-xr-x 8 root root 4096 Apr 8 16:58 opt
dr-xr-xr-x 843 root root 0 Nov 20 2019 proc
drwx------ 7 root root 4096 Mar 18 19:49 root
drwxr-xr-x 36 root root 1360 Jun 30 12:36 run
drwxr-xr-x 2 root root 12288 Jun 23 06:41 sbin
drwxr-xr-x 4 root root 4096 Nov 20 2019 snap
drwxr-xr-x 2 root root 4096 Aug 5 2019 srv
dr-xr-xr-x 13 root root 0 Dec 4 2019 sys
drwxrwxrwt 338 root root 262144 Jun 30 12:47 tmp
drwxrwxr-x 10 5640 13023 4096 May 21 20:16 usr
drwxr-xr-x 14 root root 4096 Nov 20 2019 var
lrwxrwxrwx 1 root root 31 Jun 26 06:54 vmlinuz -> boot/vmlinuz-4.15.0-108-generic
lrwxrwxrwx 1 root root 31 Jun 26 06:54 vmlinuz.old -> boot/vmlinuz-4.15.0-106-generic
怎么会发生这种情况？我需要担心吗？我可以将所有权改回“root”并撤销组的写入权限吗？还是这些所有权是出于重要原因而设置的？