Re: is_absolute_path incorrect on Windows

Bruce Momjian wrote:
> Tom Lane wrote:
> > Bruce Momjian <bruce@momjian.us> writes:
> > > Tom Lane wrote:
> > >> Bruce Momjian <bruce@momjian.us> writes:
> > >>> I have reviewed is_absolute_path() and have implemented
> > >>> path_is_relative_and_below_cwd() to cleanly handle cases like 'E:abc' on
> > >>> Win32;  patch attached.
> > >> 
> > >> This patch appears to remove some security-critical restrictions.
> > >> Why did you delete the path_contains_parent_reference calls?
> > 
> > > They are now in path_is_relative_and_below_cwd(),
> > 
> > ... and thus not invoked in the absolute-path case.  This is a security
> > hole.
> > 
> > >  I don't see a general reason to prevent
> > > ".." in absolute paths, only relative ones.
> > 
> > 	load '/path/to/database/../../../path/to/anywhere'
> 
> Ah, good point. I was thinking about someone using ".." in the part of
> the path that is compared to /data or /log, but using it after that
> would clearly be a security problem.
> 
> I have attached an updated patch that restructures the code to be
> clearer and adds the needed checks.

I decided that my convert_and_check_filename() usage was too intertwined
so I have developed a simplified version that is easier to understand; 
patch attached.

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +