Re: [PATCH] O_DIRECTORY|O_CREAT handling

[viro]

On Sun, Dec 28, 2003 at 01:03:41PM -0500, Andrew Pimlott wrote:
> On Sun, Dec 21, 2003 at 11:51:10AM +0100, Willy Tarreau wrote:
> >   base_dir="/tmp/tmpdir"; 
> >   do {
> >      rnd=random();
> >      sprintf(dir, "%s%d", base_dir, rnd);
> >   } while (!mkdir(dir, 0700);
> >   /* now I'm guaranteed that I'm the first to get this dir, */
> >   /* and only my UID can work in it */
> >   chdir(dir);
> >   
> > So the only race would be someone working with the same UID (or root) removing
> > the directory and replacing it with another one (or a symlink or anything)
> > between mkdir() and chdir().
> 
> If /tmp isn't sticky, anyone can do this.  I think this is the
> scenario Ulrich was referring to.

And if /etc/shadow is world-writable, anyone can do other interesting things.
Doctor, it hurts when I do it...
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