linux-kernel - Re: ls -l /proc/1/exe -> Permission denied

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Date:	Mon, 21 Jul 2014 00:05:06 +0200
From:	Joakim Tjernlund <joakim.tjernlund@...nsmode.se>
To:	Richard Weinberger <richard@....at>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Andreas Schwab <schwab@...ux-m68k.org>
Subject: Re: ls -l /proc/1/exe -> Permission denied

Richard Weinberger <richard@....at> wrote on 2014/07/20 22:00:02:
> 
> Am 20.07.2014 21:15, schrieb Joakim Tjernlund:
> > Richard Weinberger <richard@....at> wrote on 2014/07/20 14:05:41:
> >>
> >> Am 20.07.2014 13:51, schrieb Andreas Schwab:
> >>> Richard Weinberger <richard.weinberger@...il.com> writes:
> >>>> Do you have an example?
> >>>
> >>> proc symlinks are special because they actually resolve to the 
inode.
> >>
> >> Ah. If an attacker manages the kernel to follow the symlink he could
> >> indirectly access that file.
> >> Thanks for pointing this out!
> > 
> > That is a big if, I read this as you don't trust the kernels impl.
> > of proc sym links so paper over this with denying all other to read 
> > trivial
> > data such as the exe sym link.
> 
> Feel free to propose a solution for that. :-)

I wish I had one :) Good to know why things are how they are though. I
guess there is a reason why proc symlinks resolve to the inode?

 Jocke
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