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

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-next>] [day] [month] [year] [list]

Date:	Fri, 18 Jul 2014 17:05:32 +0200
From:	Joakim Tjernlund <joakim.tjernlund@...nsmode.se>
To:	unlisted-recipients:; (no To-header on input)
Cc:	Richard Weinberger <richard.weinberger@...il.com>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: ls -l /proc/1/exe -> Permission denied

Joakim Tjernlund/Transmode wrote on 2014/07/18 15:49:17:
> 
> Richard Weinberger <richard.weinberger@...il.com> wrote on 2014/07/18 
14:58:30:
> > 
> > On Thu, Jul 17, 2014 at 1:18 PM, Joakim Tjernlund
> > <joakim.tjernlund@...nsmode.se> wrote:
> > > Trying to real /proc/<pid>/exe I noticed I could not read links not
> > > belonging to my user such as:
> > > jocke >  ls -l /proc/1/exe
> > >              ls: cannot read symbolic link /proc/1/exe: Permission 
denied
> > >
> > > Is this expected?
> > 
> > Why do you think this is unexpected?

> It only shows the full path to the executable, compare with comm which 
shows basename(app).
> 
> I have an idea for qemu-user which needs to identify which processes
> are running /usr/bin/qemu-<arch> and which are not so it knows how
> to munge different /proc/ files.

Just to be clear, I expect to read where /proc/1/exe points, not the 
contents of the file
pointed to.

It seems that any and all symlinks are forbidden:
> ls -l /proc/1
ls: cannot read symbolic link /proc/1/cwd: Permission denied
ls: cannot read symbolic link /proc/1/root: Permission denied
ls: cannot read symbolic link /proc/1/exe: Permission denied

 Jocke
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/