O protocolo lida com essas permissões
Você precisa configurar essas permissões quando montar o compartilhamento. Veja a man page de mount.cifs
ou o link abaixo.
Tome nota especificamente das seguintes
file_mode=arg If the server does not support the CIFS Unix extensions this overrides the default file mode.
dir_mode=arg If the server does not support the CIFS Unix extensions this overrides the default mode for directories.
Há também
uid=arg sets the uid that will own all files or directories on the mounted filesystem when the server does not provide ownership information. It may be specified as either a username or a numeric uid. When not specified, the default is uid 0. The mount.cifs helper must be at version 1.10 or higher to support specifying the uid in non-numeric form. See the section on FILE AND DIRECTORY OWNERSHIP AND PERMISSIONS below for more information.
forceuid instructs the client to ignore any uid provided by the server for files and directories and to always assign the owner to be the value of the uid= option. See the section on FILE AND DIRECTORY OWNERSHIP AND PERMISSIONS below for more information.
gid=arg sets the gid that will own all files or directories on the mounted filesystem when the server does not provide ownership information. It may be specified as either a groupname or a numeric gid. When not specified, the default is gid 0. The mount.cifs helper must be at version 1.10 or higher to support specifying the gid in non-numeric form. See the section on FILE AND DIRECTORY OWNERSHIP AND PERMISSIONS below for more information.
forcegid instructs the client to ignore any gid provided by the server for files and directories and to always assign the owner to be the value of the gid= option. See the section on FILE AND DIRECTORY OWNERSHIP AND PERMISSIONS below for more information.
Parece que você quer algo semelhante a este
mount -t cifs -o username=xxx,password=xxx,file_mode=0777,dir_mode=0777 //server/share /mnt
Ou você pode restringi-lo a um usuário específico com algo como este
mount -t cifs -o username=xxx,password=xxx,uid=1000,gid=1000 //server/share /mnt