Date: Wed, 30 Sep 2015 03:37:38 +0000 (UTC) From: Gleb Smirnoff <glebius@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r288412 - head/sys/netinet Message-ID: <201509300337.t8U3bcoD046892@repo.freebsd.org>
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Author: glebius Date: Wed Sep 30 03:37:37 2015 New Revision: 288412 URL: https://svnweb.freebsd.org/changeset/base/288412 Log: When processing ICMP need frag message, ignore the suggested MTU unless it is smaller than the current one for this connection. This is behavior specified by RFC 1191, and this is how original BSD stack behaved, but this was unintentionally regressed in r182851. Reported & tested by: Richard Russo <russor whatsapp.com> Differential Revision: D3567 Sponsored by: Nginx, Inc. Modified: head/sys/netinet/tcp_subr.c Modified: head/sys/netinet/tcp_subr.c ============================================================================== --- head/sys/netinet/tcp_subr.c Wed Sep 30 03:36:41 2015 (r288411) +++ head/sys/netinet/tcp_subr.c Wed Sep 30 03:37:37 2015 (r288412) @@ -1541,11 +1541,6 @@ tcp_ctlinput(int cmd, struct sockaddr *s * in the route to the suggested new * value (if given) and then notify. */ - bzero(&inc, sizeof(inc)); - inc.inc_faddr = faddr; - inc.inc_fibnum = - inp->inp_inc.inc_fibnum; - mtu = ntohs(icp->icmp_nextmtu); /* * If no alternative MTU was @@ -1560,14 +1555,18 @@ tcp_ctlinput(int cmd, struct sockaddr *s mtu = V_tcp_minmss + sizeof(struct tcpiphdr); /* - * Only cache the MTU if it - * is smaller than the interface - * or route MTU. tcp_mtudisc() - * will do right thing by itself. + * Only process the offered MTU if it + * is smaller than the current one. */ - if (mtu <= tcp_maxmtu(&inc, NULL)) + if (mtu < tp->t_maxopd + + sizeof(struct tcpiphdr)) { + bzero(&inc, sizeof(inc)); + inc.inc_faddr = faddr; + inc.inc_fibnum = + inp->inp_inc.inc_fibnum; tcp_hc_updatemtu(&inc, mtu); - tcp_mtudisc(inp, mtu); + tcp_mtudisc(inp, mtu); + } } else inp = (*notify)(inp, inetctlerrmap[cmd]);
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