[GRASS-dev] Directory security/permission issue

[Glynn Clements]

Brad Douglas wrote:

> While looking over my working dirs, today, I noticed that all of my
> recent locations were created with 0777 permissions, instead of the
> traditional 0755 mask.  Temp directories are still created properly.
> 
> 0777 is bad form and a potential security problem.
> 
> Is there a reason for the change I missed?  A quick search through the
> archives didn't turn up anything.
> 
> It seems to have come as an accidental result of the MINGW changes.  The
> offending code can be found in lib/gis/paths.c in G_mkdir().
> 
> This should be explained or corrected before 6.2.2 is released.

The mode passed to mkdir is modified by the process' umask to obtain
the actual mode of the directory. If you're ending up with
world-writable directories, that implies that your umask is zero,
which is insecure.

Your umask should normally be at least 0022, (or 0022 if you want
files to be group-writable, which is sometimes useful); if you're
paranoid, use 0077 (i.e. no permissions for anyone but yourself).

In general, the permissions specified by a program when calling
open(), mkdir(), etc should be the maximum which the user might
possibly want (i.e. 0777 for directories and executable files, 0666
for non-executable files), as the umask can only remove permissions,
not add them.

-- 
Glynn Clements <glynn at gclements.plus.com>