From owner-freebsd-stable@freebsd.org Mon Aug 20 14:59:33 2018 Return-Path: Delivered-To: freebsd-stable@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 7A6BD1070B8F for ; Mon, 20 Aug 2018 14:59:33 +0000 (UTC) (envelope-from eugen@grosbein.net) Received: from hz.grosbein.net (hz.grosbein.net [IPv6:2a01:4f8:d12:604::2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "hz.grosbein.net", Issuer "hz.grosbein.net" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 0133771040 for ; Mon, 20 Aug 2018 14:59:32 +0000 (UTC) (envelope-from eugen@grosbein.net) Received: from eg.sd.rdtc.ru (eg.sd.rdtc.ru [IPv6:2a03:3100:c:13:0:0:0:5]) by hz.grosbein.net (8.15.2/8.15.2) with ESMTPS id w7KExNjG052690 (version=TLSv1.2 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 20 Aug 2018 16:59:24 +0200 (CEST) (envelope-from eugen@grosbein.net) X-Envelope-From: eugen@grosbein.net X-Envelope-To: stb@lassitu.de Received: from [10.58.0.4] ([10.58.0.4]) by eg.sd.rdtc.ru (8.15.2/8.15.2) with ESMTPS id w7KExIAL075971 (version=TLSv1.2 cipher=DHE-RSA-AES128-SHA bits=128 verify=NOT); Mon, 20 Aug 2018 21:59:19 +0700 (+07) (envelope-from eugen@grosbein.net) Subject: Re: Bind to port <1024 in jail To: Stefan Bethke , FreeBSD Stable References: <75536186-7D58-498C-BFC6-9284EB7CB444@lassitu.de> From: Eugene Grosbein Message-ID: <6bfc8608-946d-39eb-cc57-88b3dc3bd7c5@grosbein.net> Date: Mon, 20 Aug 2018 21:59:14 +0700 User-Agent: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <75536186-7D58-498C-BFC6-9284EB7CB444@lassitu.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=0.3 required=5.0 tests=BAYES_00,LOCAL_FROM,SPF_PASS autolearn=no autolearn_force=no version=3.4.1 X-Spam-Report: * -0.0 SPF_PASS SPF: sender matches SPF record * -2.3 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0000] * 2.6 LOCAL_FROM From my domains X-Spam-Checker-Version: SpamAssassin 3.4.1 (2015-04-28) on hz.grosbein.net X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.27 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 20 Aug 2018 14:59:33 -0000 20.08.2018 21:47, Stefan Bethke wrote: > I have a Go program (acme-dns) that wants to bind 53, 80, and 443, and I’d rather have it run as a non-privileged user. The program doesn’t provide a facility to drop privs after binding the ports. I’m planning to run it in a jail. > > After some googling, it appears that a couple of years ago I should have been able to do: > sysctl net.inet.ip.portrange.reservedhigh=0 > and allow all processes to bind to „low“ ports. This does not work in my jails on a 11-stable host. > > $ sudo sysctl net.inet.ip.portrange.reservedhigh=0 > net.inet.ip.portrange.reservedhigh: 1023 > sysctl: net.inet.ip.portrange.reservedhigh=0: Operation not permitted > > Securelevel should not interfere: > $ sysctl kern.securelevel > kern.securelevel: -1 > > Is there a way to allow regular processes to bind to low ports? Yes. Just use mac_portacl kernel module: kldload mac_portacl Once loaded, it duplicates net.inet.ip.portrange.reservedhigh protection with its own security.mac.portacl.port_high, so it's safe to disable "reservedhigh" for whole system by running sysctl net.inet.ip.portrange.reservedhigh=0 for host. The trick is that mac_portacl provides a way to selectively give permission for non-root UID to bind low ports: security.mac.portacl.rules=uid:88:tcp:80,uid:88:tcp:443,uid:53:tcp:53,uid:53:udp:53 It works just fine for a host and I use it for name servers utilizing port 53 for a box with dynamically created interfaces, so it may bind the port for distinct IP addresses after it dropped privilegies when new interface is created and get new IP assigned. I have not tried it for a jails, though. Please try and respond.