Sudo restriction: (Not to run specific commands)

kannadhasan  ALL=ALL, !/usr/sbin/visudo, !/etc/sudoers, /usr/bin/passwd, !/usr/bin/vim, !/usr/bin/gedit, !/usr/bin/geany, !/usr/bin/vi, /usr/bin/nano, /bin/chown, /bin/mount, /bin/umount

Where as, the user can run all the commands except the above.