Ubuntu 22.04 update to 6.2.0-31 kernel version breaks mount.cifs to vers=1.0 server cifs_mount failed w/return code = -5

[Michael Lueck]

My Xubuntu system this weekend alerted me to a new kernel update being available. The following versions are the existing/working version:

linux-image-6.2.0-26-generic 6.2.0-26.26~22.04.1

And the updated/not working version:

linux-image-6.2.0-31-generic 6.2.0-31.31~22.04.1

And yes I run my system with:

linux-image-generic-hwe-22.04 6.2.0.31.31~22.04.8

Booted to the 6.2.0-31 kernel version, attempting to do a mount.cifs operation to our Samba NT4 PDC, results in the following output into syslog:

Sep 4 08:03:24 jaakob kernel: [ 107.703886] FS-Cache: Loaded
Sep 4 08:03:24 jaakob kernel: [ 107.824160] Key type cifs.spnego registered
Sep 4 08:03:24 jaakob kernel: [ 107.824169] Key type cifs.idmap registered
Sep 4 08:03:24 jaakob kernel: [ 107.824454] Use of the less secure dialect vers=1.0 is not recommended unless required for access to very old servers
Sep 4 08:03:24 jaakob kernel: [ 107.824454]
Sep 4 08:03:24 jaakob kernel: [ 107.824457] CIFS: VFS: Use of the less secure dialect vers=1.0 is not recommended unless required for access to very old servers
Sep 4 08:03:24 jaakob kernel: [ 107.824460] CIFS: Attempting to mount \\ldslnx01\data
Sep 4 08:03:24 jaakob kernel: [ 107.859554] CIFS: VFS: cifs_mount failed w/return code = -5

And none of the Samba mounts will establish.

Booting back to the prior 6.2.0-26 kernel version, Samba mounts work just fine.

I use the following switches to the mount.cifs command in order to establish connections to our Samba NT4 PDC:

"-o credentials=/home/mdlueck/.smbcredentials,uid=mdlueck,gid=mdlueck,dir_mode=0777,file_mode=0666,nobrl,vers=1.0"

That last vers= option was the last that needed to be added to continue making use of our Samba NT4 style PDC.

Since it is a version upgrade of only the kernel, not Samba package, I would not think that yet another switch to mount.cifs was needed in order to continue connecting successfully. So did the latest Kernel update suddenly break Samba's mount.cifs vers=1.0 support?

Nothing gets logged to our Samba server for the failed mount attempt.

Booting for not back to the working 6.2.0-26 kernel version. Please kindly advise.

[Michael Lueck (mlueck)]

Ubuntu has release kernel version "6.2.0-32-generic #32~22.04.1-Ubuntu SMP PREEMPT_DYNAMIC Fri Aug 18 10:40:13 UTC 2 x86_64 x86_64 x86_64 GNU/Linux" which has successfully resolved this defect case.

One of the Samba maintainers told me I should check if SMB 1.0 protocol was purposely removed from the Ubuntu 6.2.0-31 kernel version. This evening I received that changelog, and could not see a hint of it being removed by Ubuntu on purpose.

Then my system notified me of a yet newer kernel package. I pulled it down, and was happy to see it has successfully resolved this defect.