SMB(CIFS) does not show all files when mounting a Windows share

I’ve been mounting Windows Shares on Linux servers for years and until recently I’ve noticed an issue with this — Some files/directories are not listed from a Windows share.

I’ve searching the internet and people are experiencing the same problem as well. It looks like a kernel bug for SMBv2+ according to the discussions below:

For systems I’ve been working on, the changes are both Windows and Linux have been upgraded — SMBv1 is not supported anymore between them. In 2017 Microsoft patched Windows Servers and advised to disable the SMBv1 protocol for security reasons. That explains why I didn’t notice it before.

On a Linux box, command “modinfo cifs” will display CIFS module info at the kernel level:

root@joetest:~/# modinfo cifs
filename:       /lib/modules/4.1.12-124.48.6.el6uek.x86_64/kernel/fs/cifs/cifs.ko
version:        2.06
description:    VFS to access servers complying with the SNIA CIFS Specification e.g. Samba and Windows
license:        GPL
author:         Steve French <sfrench@us.ibm.com>
alias:          fs-cifs
srcversion:     4CFC8FAABB534357A689526
depends:        dns_resolver
retpoline:      Y
intree:         Y
vermagic:       4.1.12-124.48.6.el6uek.x86_64 SMP mod_unload modversions
parm:           CIFSMaxBufSize:Network buffer size (not including header). Default: 16384 Range: 8192 to 130048 (uint)
parm:           cifs_min_rcv:Network buffers in pool. Default: 4 Range: 1 to 64 (uint)
parm:           cifs_min_small:Small network buffers in pool. Default: 30 Range: 2 to 256 (uint)
parm:           cifs_max_pending:Simultaneous requests to server. Default: 32767 Range: 2 to 32767. (uint)
parm:           enable_oplocks:Enable or disable oplocks. Default: y/Y/1 (bool)

And if cifs-utils package is installed, manpage of mount.cifs can be checked with “man 8 mount.cifs”

root@joetest:~/# yum info cifs-utils
Loaded plugins: security
epel/metalink                                                                                                                                                                                                         | 3.8 kB     00:00
local_ol6_latest                                                                                                                                                                                                      | 2.9 kB     00:00 ...
ol6_latest                                                                                                                                                                                                            | 2.7 kB     00:00
Installed Packages
Name        : cifs-utils
Arch        : x86_64
Version     : 4.8.1
Release     : 20.el6
Size        : 135 k
Repo        : installed
From repo   : local_ol6_latest
Summary     : Utilities for mounting and managing CIFS mounts
URL         : http://linux-cifs.samba.org/cifs-utils/
License     : GPLv3
Description : The SMB/CIFS protocol is a standard file sharing protocol widely deployed
            : on Microsoft Windows machines. This package contains tools for mounting
            : shares on Linux using the SMB/CIFS protocol. The tools in this package
            : work in conjunction with support in the kernel to allow one to mount a
            : SMB/CIFS share onto a client and use it as if it were a standard Linux
            : file system.

On Windows side, the article from Microsoft explains how to check, disable & enable a specific version of SMB using powershell.

For examples:

PS C:\Windows\system32> Get-WindowsOptionalFeature -Online -FeatureName smb1protocol


FeatureName      : SMB1Protocol
DisplayName      : SMB 1.0/CIFS File Sharing Support
Description      : Support for the SMB 1.0/CIFS file sharing protocol, and the Computer Browser protocol.
RestartRequired  : Possible
State            : Disabled
CustomProperties :
                   ServerComponent\Description : Support for the SMB 1.0/CIFS file sharing protocol, and the Computer Browser protocol.
                   ServerComponent\DisplayName : SMB 1.0/CIFS File Sharing Support
                   ServerComponent\Id : 487
                   ServerComponent\Type : Feature
                   ServerComponent\UniqueName : FS-SMB1
                   ServerComponent\Deploys\Update\Name : SMB1Protocol

PS C:\Users\Administrator> Enable-WindowsOptionalFeature -Online -FeatureName smb1protocol
Do you want to restart the computer to complete this operation now?
[Y] Yes  [N] No  [?] Help (default is "Y"): N


Path           :
Online         : True
Restart Needed : True

PS C:\Users\Administrator> Disable-WindowsOptionalFeature -Online -FeatureName smb1protocol
Do you want to restart the computer to complete this operation now?
[Y] Yes  [N] No  [?] Help (default is "Y"): N


Path           :
Online         : True
Restart Needed : True

Using Get-SmbServerConfiguration / Set-SmbServerConfiguration for EnableSMB1Protocol/EnableSMB2Protocol/ EnableSMB3Protocol which doesn’t need a restart of the server.

Get-SmbServerConfiguration | Select EnableSMB2Protocol
Set-SmbServerConfiguration -EnableSMB2Protocol $false
Set-SmbServerConfiguration -EnableSMB2Protocol $true