Google Chrome - Block drive browse, allow html open

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Hi all

 

I realise I'm after 2 contradictory things with this, but someone will hopefully be able to help.

 

I need to deploy Google Chrome and want to block students from browsing C drive which I can do by blocking file:// in the Block Access to a list of URLs, however this then blocks them from opening html files from any drive also as it uses file:///.

 

Anyone any hints as to how I can block users from browsing certain drives but still allow them to open html files? I did initially try file:///c:/* but that didn't seem to apply.