[Click] Question: Script "cat" handler considered dangerous?

[Bart Braem]

On 16 Jun 2008, at 18:37, Eddie Kohler wrote:

> A quick question.  I've justed added a handler to Click's Script  
> element,
> accessible at userlevel, called "cat".  This handler reads a file  
> and returns
> its contents.  For example:
>
> Script(set x $(cat /tmp/f))
>
> sets the script's "$x" variable to the contents of /tmp/f.
>
> This is pretty useful, but also potentially dangerous, since anyone  
> who can
> call the Script's "cat" handler can read any file accessible to the  
> click
> program.  I am wondering if anyone finds this dangerous -- for  
> example if
> someone is running ControlSocket.  One possibility would be to make  
> "cat"
> accessible within the config, and not from ControlSocket.


Hi Eddie,

Could you give an example of where this might be useful? I think there  
is a large coupling between your system and your router if you need  
this, but perhaps I'm mistaken.

I personally think it's dangerous, as a ControlSocket has no  
authentication at all. For now that's not really a problem because of  
the limited capabilities of a router, but it would become more  
dangerous. We would have to be very careful not to write any code that  
might result in that script being called. Also in new elements...

On the other hand, if one already runs Click as root, you should know  
the implied dangers.

Regards,
Bart
-- 
Bart Braem
PATS research group - IBBT
Dept. of Mathematics and Computer Sciences
University of Antwerp
Campus Middelheim, G2.36
Middelheimlaan 1
B-2020 Antwerpen, Belgium
Phone: +32 (0)3 265.32.91
Fax: +32 (0)3 265.37.77
Web: www.pats.ua.ac.be