Re: lynx-dev form options

[Mike Castle]

Amazingly enough Leonid Pauzner said:
> >      * From: address@hidden (Mike Castle)
> One security item:
> Some options may be disabled in gen_options() by "if (!no_dots)" etc.,
> but this is still open in postoptions() for those who change options's HTML
> manually, so we should merge restrictions from gen_options() to postoptions()
> and keep this invariant clear.
> I think no more security problems here.

This is *precisely* what I was referring to here:

> > I wanted to avoid excessively complicating the backend processing of the
> > posted form input.  I wanted to have one location to check for the
> > security/validity of enabling certain features; specifically when the html
> > is generated.  I know the difficulty of having to keep mulitple sections of
> > code in sync, and trying to maintain any security aspects where both the
> > html is generated and the posted data is processed will be a nightmare.
> > Sure, when adding new features, care can be taken.  But somewhere down the
> > line, one part will be enhanced and the other missed; someone will exploit
> > it.


Like I said:  I think trying to handle it in both locations is an extremely
bad idea.  Because someone will eventually mess up and forget to modify
both sections of code and somewhere along the line open up a hole.

The only proper way that I can see to close this up is to generate a one
shot item each time get_options is called (the "secure" input field), and
when postoption processes it, verifies it.  Also, \ rendering should be
disabled for this page (otherwise when using an anon account, one can
figure out what the oneshot passcode is, and spoof it). 

Once "secure" is working, then there is no longer any need to keep other
security aspects in both gen_options() and postoptions() in sync.

mrc
-- 
       Mike Castle       Life is like a clock:  You can work constantly
  address@hidden  and be right all the time, or not work at all
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