default vers value when mounting cifs shares with mount.cifs not working

Bug #1749214 reported by Dave Ford on 2018-02-13
This bug affects 1 person
Affects Status Importance Assigned to Milestone
linux (Ubuntu)

Bug Description

Firstly, apologies if this isn't a bug in cifs.mount - I know it's intimitly connected to a recent kernel updates which changed the default SMB version cifs connects with, but I'm having trouble distinguishing whether this behaviour is caused by the kernel change or a problem with cifs.

On a recently built 16.04.3 LTS box with kernel 4.4.0-109, I was able to mount to a network DFS share with the following

mount.cifs -o user=username //pathto/share /mountpoint

and after doing so, I was able to navigate through the mounted share, and through the underlying DFS structure with no problems. The mount command notably contained 'vers=1.0' - which was expected.

After updating the kernel to, if I run the same command, the share appears to mount, but I get a 'cannot access ...: Input/Output error' when trying to move through a DFS mount within the mounted filesystem.

Notably, the output from the mount command has 'vers=default'.

I understand from various sources, that the default SMB vers is now 3.0 - and if I mount this share explicitly with

mount.cifs -o user=username,vers=3.0 //pathto/share /mountpoint

Then I see 'vers=3' on the output from mount, and am able to use the share as expected.

The man page for the cifs.mount cmd still says the default is SMB1.0 (this appeared to be the case with a kernel previous to 4.13). The kernel sources now say the default is SMB 3.0 - which would also be find, if the share is mounted with vers=3.0.

But instead I'm seeing 'vers=default' - and I'm unsure as to what version of SMB it's actually trying to use (if any) - whatever it is, it doesn't work unless I explicitly set vers=3.0.

 total 0
 crw-rw---- 1 root audio 116, 1 Feb 13 12:02 seq
 crw-rw---- 1 root audio 116, 33 Feb 13 12:02 timer
AplayDevices: Error: [Errno 2] No such file or directory
ApportVersion: 2.20.1-0ubuntu2.15
Architecture: amd64
ArecordDevices: Error: [Errno 2] No such file or directory
AudioDevicesInUse: Error: command ['fuser', '-v', '/dev/snd/seq', '/dev/snd/timer'] failed with exit code 1:
CRDA: Error: command ['iw', 'reg', 'get'] failed with exit code 1: nl80211 not found.
DistroRelease: Ubuntu 16.04
HibernationDevice: RESUME=UUID=4d912473-ae08-4591-886b-eff2cb5edfd9
InstallationDate: Installed on 2017-07-11 (217 days ago)
InstallationMedia: Ubuntu-Server 16.04.2 LTS "Xenial Xerus" - Release amd64 (20170215.8)
IwConfig: Error: [Errno 2] No such file or directory
Lsusb: Error: command ['lsusb'] failed with exit code 1:
MachineType: VMware, Inc. VMware Virtual Platform
Package: linux (not installed)


ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-4.13.0-32-generic root=UUID=d702a195-430c-4bf2-9753-6618837863dc ro
ProcVersionSignature: Ubuntu 4.13.0-32.35~16.04.1-generic 4.13.13
 linux-restricted-modules-4.13.0-32-generic N/A
 linux-backports-modules-4.13.0-32-generic N/A
 linux-firmware 1.157.15
RfKill: Error: [Errno 2] No such file or directory
Tags: xenial
Uname: Linux 4.13.0-32-generic x86_64
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: oracle
_MarkForUpload: True 04/05/2016
dmi.bios.vendor: Phoenix Technologies LTD
dmi.bios.version: 6.00 440BX Desktop Reference Platform
dmi.board.vendor: Intel Corporation
dmi.board.version: None
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 1
dmi.chassis.vendor: No Enclosure
dmi.chassis.version: N/A
dmi.modalias: dmi:bvnPhoenixTechnologiesLTD:bvr6.00:bd04/05/2016:svnVMware,Inc.:pnVMwareVirtualPlatform:pvrNone:rvnIntelCorporation:rn440BXDesktopReferencePlatform:rvrNone:cvnNoEnclosure:ct1:cvrN/A: VMware Virtual Platform
dmi.product.version: None
dmi.sys.vendor: VMware, Inc.

Dave Ford (d-ford) on 2018-02-13
summary: - default vers value
+ default vers value when mounting cifs shares with mount.cifs not working
description: updated

This bug is missing log files that will aid in diagnosing the problem. While running an Ubuntu kernel (not a mainline or third-party kernel) please enter the following command in a terminal window:

apport-collect 1749214

and then change the status of the bug to 'Confirmed'.

If, due to the nature of the issue you have encountered, you are unable to run this command, please add a comment stating that fact and change the bug status to 'Confirmed'.

This change has been made by an automated script, maintained by the Ubuntu Kernel Team.

Changed in linux (Ubuntu):
status: New → Incomplete

apport information

tags: added: apport-collected xenial
description: updated

apport information

Dave Ford (d-ford) wrote : Lspci.txt

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Changed in linux (Ubuntu):
status: Incomplete → Confirmed
Joseph Salisbury (jsalisbury) wrote :

Would it be possible for you to test the latest upstream kernel? Refer to . Please test the latest v4.16 kernel[0].

If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'.

If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'.

Once testing of the upstream kernel is complete, please mark this bug as "Confirmed".

Thanks in advance.


Changed in linux (Ubuntu):
importance: Undecided → Medium
status: Confirmed → Incomplete
tags: added: needs-bisect
Dave Ford (d-ford) wrote :

Ahh - that seems like it might have got it. Mounted smb share is working correctly.

mount still returns the vers=default, but I'm assuming that whatever 'default' is is now working.

Dave Ford (d-ford) wrote :

Tested with kernel linux-image-4.16.0-041600rc1-generic_4.16.0-041600rc1.201802120030_amd64.deb

Dave Ford (d-ford) on 2018-02-14
tags: added: kernel-fixed-upstream
Launchpad Janitor (janitor) wrote :

[Expired for linux (Ubuntu) because there has been no activity for 60 days.]

Changed in linux (Ubuntu):
status: Incomplete → Expired
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