Estranho, estou consultando o manual ("man smb.conf") ele diz que a diretiva "veto files" é de compartilhamento (S), não global.
"This is a list of files and directories that are neither visible nor accessible. Each entry in the list must be separated by a '/', which allows spaces to be included in the entry. '*' and '?' can be used to specify multiple files or directories as in DOS wildcards.
Each entry must be an unix path, not a DOS path and must not include the unix directory separator '/'.
Note that the case sensitive option is applicable in vetoing files.
One feature of the veto files parameter that is important to be aware is Samba's behaviour when trying to delete a directory. If a directory that is to be deleted contais nothing but veto files this deletion will fail unless you also set the delete veto files parameter to yes.
Setting this parameter will affect the performance of Samba, as it will be forced to check all files and directories for a match as they are scanned."