bugtraq - Re: /proc filesystem allows bypassing directory permissions on Linux

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date: Mon, 26 Oct 2009 11:47:18 +0100
From: Pavel Machek <pavel@....cz>
To: Dan Yefimov <dan@...htwave.net.ru>
Cc: psz@...hs.usyd.edu.au, bugtraq@...urityfocus.com
Subject: Re: /proc filesystem allows bypassing directory permissions on
 Linux

On Mon 2009-10-26 13:42:17, Dan Yefimov wrote:
> On 25.10.2009 2:40, psz@...hs.usyd.edu.au wrote:
> >Dear Pavel,
> >
> >>... that's exactly the problem.
> >
> >I see, the /proc/*/fd/* objects seem "confused": are they symlinks,
> >hardlinks, or open file descriptors? I guess should always act as
> >the latter, where access mode flags (O_RDONLY or O_RDWR) are set at
> >open() and not changeable afterwards in fcntl(). Any open() on them
> >should behave as a dup().
> >
> Paul, in authentic kernels /proc/<PID>/fd/<FD> are symlinks, not
> anything other. There're no such publicly accessible file objects,
> as file descriptors, there're only files (including special ones),
> directories and symlinks. But the above words don't necessary relate
> to patched kernels like distributed by third parties.

Check your facts. Those symlinks are special.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html