[PATCH] cifs: Workaround a probable Samba case sensitivity bug

Alexander Perlis aperlis at math.lsu.edu
Fri Jul 25 18:23:49 MDT 2014

On Jun 22, Shirish Pargaonkar wrote:
 > When a client supports extended security but server does not,
 > and that client, in Flags2 field of smb header indicates that
 > - it supports extended security negotiation
 > - it does not support security signatures
 > - it does not require security signatures
 > Samba server treats a client as a Vista client.
 > That turns off case sensitivity and that is a problem for
 > cifs vfs client.

I can report that this bug is affecting folks in production 
environments. It seems a newer version of the kernel cifs client code is 
reporting capabilities that are confusing the Samba server into turning 
off case sensitivity, which breaks a lot of stuff.

For example, on our Samba server we have "case sensitive = Auto" because 
we have both Linux and Windows clients. Our older Linux clients running 
Kubuntu 10.04 indeed obtain the desired case sensitive connections, but 
when we try to upgrade a client to Kubuntu 12.04 with the 14.04 LTS 
enablement stack, the mounts suddenly become case insensitive, after 
which it's not too hard to confuse the client into dropping the 
"serverino" flag on the connection (manually you can do "mkdir Test; cd 
tesT"), after which KDE locking code goes bonkers.

In the referenced post,
Shirish Pargaonkar included a one-line patch to the Samba server 
negprot.c code that fixes this bug.

No one replied, so unclear whether it got missed? What's the procedure 
to get that fix into the Samba codebase? Is reporting on this list 
sufficient, or does a separate bug report need to be entered somewhere 
into a bug tracking system?


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