From mla_strick@att.net Wed Dec 23 20:29:38 2009 Return-Path: Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 5B7CF1065696 for ; Wed, 23 Dec 2009 20:29:38 +0000 (UTC) (envelope-from mla_strick@att.net) Received: from smtp125.sbc.mail.sp1.yahoo.com (smtp125.sbc.mail.sp1.yahoo.com [69.147.65.184]) by mx1.freebsd.org (Postfix) with SMTP id 40F668FC25 for ; Wed, 23 Dec 2009 20:29:38 +0000 (UTC) Received: (qmail 91106 invoked from network); 23 Dec 2009 20:02:57 -0000 Received: from adsl-69-228-80-86.dsl.pltn13.pacbell.net (mla_strick@69.228.80.86 with login) by smtp125.sbc.mail.sp1.yahoo.com with SMTP; 23 Dec 2009 12:02:57 -0800 PST Received: from mist.nodomain (localhost [127.0.0.1]) by mist.nodomain (8.14.3/8.14.3) with ESMTP id nBNK2vLZ010893; Wed, 23 Dec 2009 12:02:57 -0800 (PST) (envelope-from mla@mist.nodomain) Received: (from dan@localhost) by mist.nodomain (8.14.3/8.14.3/Submit) id nBNK2vkL010892; Wed, 23 Dec 2009 12:02:57 -0800 (PST) (envelope-from mla) Message-Id: <200912232002.nBNK2vkL010892@mist.nodomain> Date: Wed, 23 Dec 2009 12:02:57 -0800 (PST) From: Dan Strick Reply-To: Dan Strick To: FreeBSD-gnats-submit@freebsd.org Cc: mla@mist.nodomain Subject: either xterm -C or ioctl TIOCCONS is broken X-Send-Pr-Version: 3.113 X-GNATS-Notify: >Number: 141928 >Category: kern >Synopsis: [libteken] either xterm -C or ioctl TIOCCONS is broken >Confidential: no >Severity: non-critical >Priority: low >Responsible: ed >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Wed Dec 23 20:30:01 UTC 2009 >Closed-Date: >Last-Modified: Wed Dec 30 23:40:06 UTC 2009 >Originator: Dan Strick >Release: FreeBSD 8.0-RELEASE i386 >Organization: none >Environment: System: FreeBSD mist 8.0-RELEASE FreeBSD 8.0-RELEASE #5: Mon Dec 7 18:59:52 PST 2009 root@mist:/usr/src/sys/i386/compile/MIST_DEBUG i386 xterm-247 xorg 7.4 >Description: The -C option to the xterm program is broken. It is supposed to redirect console messages to the xterm window by issuing the tty TIOCCONS ioctl for the xterm pty. This was working in FreeBSD 6.1 (for example), but since then the ioctl seems to have been modified to require root privilege and the xterm program has been reconfigured to drop root privilege almost immediately after starting. The xterm program requires that /dev/console belongs to the current effective user-id and this used to be all that the TIOCCONS ioctl required. (Otherwise why does /etc/fbtab exist?) >How-To-Repeat: Make some non-root user the owner of /dev/console and do "xterm -C" as that user. Then do something that generates console output (e.g. plug in a usb device). Note that the output went to the real console and not to the xterm window. >Fix: Either modify the TIOCCONS iotcl so that root privilege is not required if /dev/console belongs to the current effective user-id or rebuild xterm to not drop root privilege until it execs the user's shell within the xterm window. For example, as root: 1) cd /usr/ports/x11/xterm 2) Append "--enable-setuid" to the CONFIGURE_ARGS+= line in the Makefile. 3) make install clean Presumably someone thought they had good reasons for breaking xterm -C. There are security issues buried here and xterm is an extraordinarily messy program, but console output redirection is a rather important feature. Was it really necessary to castrate the TIOCCONS ioctl? Reenabling this ioctl seems to be the simplest and least risky way to fix xterm -C. Playing games with /etc/syslog.conf is ugly and clumsy and doing something like "tail -f /var/log/messages" in the xterm window is ugly and clumsy and unreliable. >Release-Note: >Audit-Trail: Responsible-Changed-From-To: freebsd-bugs->ed Responsible-Changed-By: linimon Responsible-Changed-When: Wed Dec 23 20:32:18 UTC 2009 Responsible-Changed-Why: ed, can you advise please? I'm guessing at the categorization. http://www.freebsd.org/cgi/query-pr.cgi?pr=141928 From: Ed Schouten To: bug-followup@FreeBSD.org, mla_strick@att.net Cc: Subject: Re: kern/141928: [libteken] either xterm -C or ioctl TIOCCONS is broken Date: Sat, 26 Dec 2009 14:38:00 +0100 --3TeSZ3lw9yLEF8lD Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hello Dan, The reason why I changed it to the way it is right now, is because it's more in line with the futuristic security model we'll hopefully gain in the future. Letting the permission to use TIOCCONS depend on the file attributes of a random character device surely isnt't the way to go. Robert Watson and I discussed this and I am considering adding a sysctl to the kernel to allow TIOCCONS to be used without any superuser privileges. Would that suit your needs? Merry Christmas, --=20 Ed Schouten WWW: http://80386.nl/ --3TeSZ3lw9yLEF8lD Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAks2EbgACgkQ52SDGA2eCwUN5ACfcZZ4JPXDiWjziizO5jXwkWkB AQ0An0uTTv1DLg+j6hOy1de9aCwADeVs =/hKc -----END PGP SIGNATURE----- --3TeSZ3lw9yLEF8lD-- From: Dan Strick To: bug-followup@freebsd.org, ed@80386.nl Cc: mla@mist.nodomain Subject: Re: kern/141928: either xterm -C or ioctl TIOCCONS is broken Date: Wed, 30 Dec 2009 15:35:35 -0800 (PST) > Letting the permission to use TIOCCONS depend on the file > attributes of a random character device surely isnt't the way to go. > > Robert Watson and I discussed this and I am considering adding a sysctl > to the kernel to allow TIOCCONS to be used without any superuser > privileges. Would that suit your needs? That should work for me since I am the only person who can log onto my workstation (assuming I can set the sysctl in /boot/loader.conf). A public workstation might need finer control over the privilege. Dan Strick From: Ed Schouten To: Dan Strick Cc: bug-followup@freebsd.org Subject: Re: kern/141928: either xterm -C or ioctl TIOCCONS is broken Date: Thu, 31 Dec 2009 00:38:20 +0100 --x7n88EPMnfci8OF7 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable * Dan Strick wrote: > That should work for me since I am the only person who can log onto my > workstation (assuming I can set the sysctl in /boot/loader.conf). > A public workstation might need finer control over the privilege. Sure, but that's hopefully something the TrustedBSD folks could provide in the future. I'll write a patch one of these days. Happy new year, --=20 Ed Schouten WWW: http://80386.nl/ --x7n88EPMnfci8OF7 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.10 (FreeBSD) iEYEARECAAYFAks75GwACgkQ52SDGA2eCwU6cACeO1rYLnNyBvVBx8T3AoiAwZcI rhMAn0mADv6ki8mGQuHcQlmyFBneES7u =NX/m -----END PGP SIGNATURE----- --x7n88EPMnfci8OF7-- >Unformatted: