In openSUSE 12.3 running kernel 3.7.10 with cifs-utils-5.9-3.4.1, I needed no sec= option in fstab to mount my Dreambox DVB receiver's shares. The Dreambox reports samba-3.0.37-r8, which is not upgradeable, and does not function with security = user in its smb.conf. The same fstab entry used in openSUSE 13.1M4 running kernel 3.10.1 with cifs-utils-5.9-6.4 fails with "mount error(13): Permission denied; Refer to the mount.cifs(8) manual page (e.g. man mount.cifs)". To mount successfully I found it necessary to add sec=none to the fstab options. Now, when sec is specified to be none, and the share mounted, the mount command reports sec=ntlm.
This code has changed since that older kernel, but there was still a problem (sec=none would not be displayed at all when specified on mount for cifs mounts in /proc/mounts).
The attached patch fixes that so /proc/mounts now shows "sec=none" in mount options when specified either on mount or in fstab
Created attachment 11434 [details]
patch to display sec=none properly in /proc/mounts
Will be in 4.3 kernel