Author: marius Date: Thu Jun 7 15:03:47 2018 New Revision: 334787 URL: https://svnweb.freebsd.org/changeset/base/334787
Log: MFC: r334443 (by cem@) 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 When superseded value is 0, MTU value is not updated at all.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: <jimp AT pfsense.org> Relnotes: yes (potentially surprising behavior change w/ broken dhcpd mtu) Differential Revision: https://reviews.freebsd.org/D15484 Modified: stable/11/sbin/dhclient/dhclient.c stable/11/sbin/dhclient/dhclient.conf.5 Directory Properties: stable/11/ (props changed) Modified: stable/11/sbin/dhclient/dhclient.c ============================================================================== --- stable/11/sbin/dhclient/dhclient.c Thu Jun 7 14:46:52 2018 (r334786) +++ stable/11/sbin/dhclient/dhclient.c Thu Jun 7 15:03:47 2018 (r334787) @@ -828,11 +828,23 @@ 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: stable/11/sbin/dhclient/dhclient.conf.5 ============================================================================== --- stable/11/sbin/dhclient/dhclient.conf.5 Thu Jun 7 14:46:52 2018 (r334786) +++ stable/11/sbin/dhclient/dhclient.conf.5 Thu Jun 7 15:03:47 2018 (r334787) @@ -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 } _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
