Regression CIFS mounted DFS
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
New
|
Undecided
|
Unassigned | ||
Jammy |
Incomplete
|
Undecided
|
Unassigned |
Bug Description
On Ubuntu 22.04.3 LTS (jammy jellyfish) we mount a DFS file service using CIFS with kerberos authentication. After the kernel upgrade from 5.15.0-86-generic to 5.15.0-88-generic (exact version: 5.15.0-88.98) this stopped working. The mount seems to have worked, but files and directories are inaccessible. A non-DFS CIFS share mounted on the same client machine is not affected.
In our case the filesystem is mounted using autofs with the following mapping:
/dfs-share -fstype=
Kernel log messages:
CIFS: Attempting to mount \\example.com\share
CIFS: VFS: BAD_NETWORK_NAME: \\example.com\share
CIFS: VFS: Verify user has a krb5 ticket and keyutils is installed
CIFS: VFS: \\CLx-Ny.
We confirmed that kernel version 5.15.0-88 causes this by booting different kernel versions repeatedly. When booting 5.15.0-86 everything worked properly as before.
Though not familiar with kernel coding, we found changes in the source code that seem to confirm that some code dealing with DFS has changed, moved, or removed.
After:
git clone git://git.
This:
git diff Ubuntu-5.15.0-86.96 Ubuntu-5.15.0-88.98 -- fs/cifs/
This suggests the function cifs_dfs_do_mount() has been (re)moved.
no longer affects: | linux-signed (Ubuntu) |
tags: | added: seg |
pulled in via upstream stable updates from 5.15.124
commit 015222ee0044b07 5c205010f3a6add 2ed79e1159
Author: Paulo Alcantara <email address hidden>
Date: Tue Oct 4 18:41:20 2022 -0300
cifs: use fs_context for automounts
BugLink: https:/ /bugs.launchpad .net/bugs/ 2035400
I don't see a fix for this in upstream v5.15.x (currently at .138), so I'm not sure if a newer mainline would work, but you could give them a go. Fetch from https:/ /kernel. ubuntu. com/mainline/ and install two debs for a version, linux-image- unsigned and linux-modules (copy locally, then just 'sudo dpkg -i <deb>').