From owner-svn-src-head@freebsd.org Thu May 31 19:36:26 2018 Return-Path: Delivered-To: svn-src-head@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 2B511FD19EF; Thu, 31 May 2018 19:36:26 +0000 (UTC) (envelope-from cem@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "mxrelay.nyi.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id CDE2679B5C; Thu, 31 May 2018 19:36:25 +0000 (UTC) (envelope-from cem@FreeBSD.org) Received: from repo.freebsd.org (repo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:0]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 94BB71E88D; Thu, 31 May 2018 19:36:25 +0000 (UTC) (envelope-from cem@FreeBSD.org) Received: from repo.freebsd.org ([127.0.1.37]) by repo.freebsd.org (8.15.2/8.15.2) with ESMTP id w4VJaPEH077140; Thu, 31 May 2018 19:36:25 GMT (envelope-from cem@FreeBSD.org) Received: (from cem@localhost) by repo.freebsd.org (8.15.2/8.15.2/Submit) id w4VJaPDo077138; Thu, 31 May 2018 19:36:25 GMT (envelope-from cem@FreeBSD.org) Message-Id: <201805311936.w4VJaPDo077138@repo.freebsd.org> X-Authentication-Warning: repo.freebsd.org: cem set sender to cem@FreeBSD.org using -f From: Conrad Meyer Date: Thu, 31 May 2018 19:36:25 +0000 (UTC) To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r334443 - head/sbin/dhclient X-SVN-Group: head X-SVN-Commit-Author: cem X-SVN-Commit-Paths: head/sbin/dhclient X-SVN-Commit-Revision: 334443 X-SVN-Commit-Repository: base MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 31 May 2018 19:36:26 -0000 Author: cem Date: Thu May 31 19:36:24 2018 New Revision: 334443 URL: https://svnweb.freebsd.org/changeset/base/334443 Log: dhclient(8): allow to supersede interface-mtu option In some cases broken DHCP servers might send invalid MTU value, so allow to use 'supersede' in dhclient.conf to override this. When superseded value is 0, MTU value is not updated at all. PR: 206721 Submitted by: novel@ Reported by: MFC after: 37 minutes (if you care about 11, please MFC to 11.2) Relnotes: yes (potentially surprising behavior change w/ broken dhcpd mtu) Differential Revision: https://reviews.freebsd.org/D15484 Modified: head/sbin/dhclient/dhclient.c head/sbin/dhclient/dhclient.conf.5 Modified: head/sbin/dhclient/dhclient.c ============================================================================== --- head/sbin/dhclient/dhclient.c Thu May 31 16:48:08 2018 (r334442) +++ head/sbin/dhclient/dhclient.c Thu May 31 19:36:24 2018 (r334443) @@ -849,11 +849,23 @@ bind_lease(struct interface_info *ip) opt = &ip->client->new->options[DHO_INTERFACE_MTU]; if (opt->len == sizeof(u_int16_t)) { - u_int16_t mtu = be16dec(opt->data); - if (mtu < MIN_MTU) - warning("mtu size %u < %d: ignored", (unsigned)mtu, MIN_MTU); + u_int16_t mtu = 0; + bool supersede = (ip->client->config->default_actions[DHO_INTERFACE_MTU] == + ACTION_SUPERSEDE); + + if (supersede) + mtu = getUShort(ip->client->config->defaults[DHO_INTERFACE_MTU].data); else + mtu = be16dec(opt->data); + + if (mtu < MIN_MTU) { + /* Treat 0 like a user intentionally doesn't want to change MTU and, + * therefore, warning is not needed */ + if (!supersede || mtu != 0) + warning("mtu size %u < %d: ignored", (unsigned)mtu, MIN_MTU); + } else { interface_set_mtu_unpriv(privfd, mtu); + } } /* Write out the new lease. */ Modified: head/sbin/dhclient/dhclient.conf.5 ============================================================================== --- head/sbin/dhclient/dhclient.conf.5 Thu May 31 16:48:08 2018 (r334442) +++ head/sbin/dhclient/dhclient.conf.5 Thu May 31 19:36:24 2018 (r334443) @@ -38,7 +38,7 @@ .\" .\" $FreeBSD$ .\" -.Dd January 1, 1997 +.Dd May 31, 2018 .Dt DHCLIENT.CONF 5 .Os .Sh NAME @@ -227,6 +227,14 @@ rather than any value supplied by the server, these va in the .Ic supersede statement. +.Pp +Some options values have special meaning: +.Bl -tag -width indent +.It Ar interface-mtu +Any server-supplied interface MTU is ignored by the client if a +.Ic supersede +zero value is configured. +.El .It Xo .Ic prepend No { Op Ar option declaration .Oo , Ar ... option declaration Oc }