From owner-freebsd-bugs@FreeBSD.ORG  Sun Jun  8 23:36:45 2014
Return-Path: <owner-freebsd-bugs@FreeBSD.ORG>
Delivered-To: freebsd-bugs@FreeBSD.org
Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id 8C21D88A
 for <freebsd-bugs@FreeBSD.org>; Sun,  8 Jun 2014 23:36:45 +0000 (UTC)
Received: from kenobi.freebsd.org (kenobi.freebsd.org
 [IPv6:2001:1900:2254:206a::16:76])
 (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id 7414D23AD
 for <freebsd-bugs@FreeBSD.org>; Sun,  8 Jun 2014 23:36:45 +0000 (UTC)
Received: from bugs.freebsd.org ([127.0.1.118])
 by kenobi.freebsd.org (8.14.8/8.14.8) with ESMTP id s58Najvs042151
 for <freebsd-bugs@FreeBSD.org>; Mon, 9 Jun 2014 00:36:45 +0100 (BST)
 (envelope-from bz-noreply@freebsd.org)
From: bz-noreply@freebsd.org
To: freebsd-bugs@FreeBSD.org
Subject: [Bug 121073] [kernel] [patch] run chroot as an unprivileged user
Date: Sun, 08 Jun 2014 23:36:45 +0000
X-Bugzilla-Reason: AssignedTo
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: Base System
X-Bugzilla-Component: kern
X-Bugzilla-Version: 8.0-CURRENT
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: Affects Only Me
X-Bugzilla-Who: Jille@quis.cx
X-Bugzilla-Status: In Discussion
X-Bugzilla-Priority: Normal
X-Bugzilla-Assigned-To: freebsd-bugs@FreeBSD.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-121073-8-1wJ45O4hNY@https.bugs.freebsd.org/bugzilla/>
In-Reply-To: <bug-121073-8@https.bugs.freebsd.org/bugzilla/>
References: <bug-121073-8@https.bugs.freebsd.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: 7bit
X-Bugzilla-URL: https://bugs.freebsd.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: freebsd-bugs@freebsd.org
X-Mailman-Version: 2.1.18
Precedence: list
List-Id: Bug reports <freebsd-bugs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-bugs>,
 <mailto:freebsd-bugs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-bugs/>
List-Post: <mailto:freebsd-bugs@freebsd.org>
List-Help: <mailto:freebsd-bugs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-bugs>,
 <mailto:freebsd-bugs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sun, 08 Jun 2014 23:36:45 -0000

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=121073

--- Comment #7 from Jille@quis.cx ---
I remember someone saying this could be exploited using rfork. I don't know why
it's not listed in this bug.

IIRC the problem was that fd_rdir (root of the processes) was stored in
proc->p_fd (struct filedesc) and the P_NOSUGID-flag in struct proc itself. One
could use rfork to create a new process with the same descriptor table and call
chroot in the child which would flag the child with P_NOSUGID but change to
root for the parent as well. The parent doesn't get P_NOSUGID however and will
be able to execve a setuid executable with a fake libc.

-- 
You are receiving this mail because:
You are the assignee for the bug.