Re: /proc filesystem allows bypassing directory permissions on Linux

On Mon, 26 Oct 2009, Matthew Dempsky wrote:
> On Mon, Oct 26, 2009 at 9:01 AM, Tony Finch <dot@dotat.at> wrote:
> >
> > Attacker uses openat() to open and modify the "private" file.
>
> At least with Linux 2.6.18, you still need +x permission on the
> directory to access its contents using openat(2).

According to POSIX, if you open the directory with O_SEARCH then openat()
does not re-check search (+x) permissions.

Tony.
-- 
f.anthony.n.finch  <dot@dotat.at>  http://dotat.at/
GERMAN BIGHT HUMBER: SOUTHWEST 5 TO 7. MODERATE OR ROUGH. SQUALLY SHOWERS.
MODERATE OR GOOD.