For you all queries about Malayalam fonts just visit –smc.org.in
Download AjaliOldlipi and Rachana fonts
and copy to fonts:///
[for that open a window press ctrl+l then type fonts:///]
restart the browser
now you can read malayalm fonts
If you want it to be available to all users copy it to /usr/share/fonts. You can check whether the fonts are installed correctly by running the command fc-list (eg. fc-list |grep Rachana ).