574 lines
14 KiB
C
574 lines
14 KiB
C
/*-
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* SPDX-License-Identifier: BSD-3-Clause
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*
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* Copyright (c) 1982, 1986, 1988, 1990, 1993, 1994, 1995
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* The Regents of the University of California. All rights reserved.
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* Copyright (c) 2007-2008,2010
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* Swinburne University of Technology, Melbourne, Australia.
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* Copyright (c) 2009-2010 Lawrence Stewart <lstewart@freebsd.org>
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* Copyright (c) 2010 The FreeBSD Foundation
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* Copyright (c) 2010-2011 Juniper Networks, Inc.
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* Copyright (c) 2019 Richard Scheffenegger <srichard@netapp.com>
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* All rights reserved.
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*
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* Portions of this software were developed at the Centre for Advanced Internet
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* Architectures, Swinburne University of Technology, by Lawrence Stewart,
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* James Healy and David Hayes, made possible in part by a grant from the Cisco
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* University Research Program Fund at Community Foundation Silicon Valley.
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*
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* Portions of this software were developed at the Centre for Advanced
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* Internet Architectures, Swinburne University of Technology, Melbourne,
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* Australia by David Hayes under sponsorship from the FreeBSD Foundation.
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*
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* Portions of this software were developed by Robert N. M. Watson under
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* contract to Juniper Networks, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)tcp_ecn.c 8.12 (Berkeley) 5/24/95
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*/
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/*
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* Utility functions to deal with Explicit Congestion Notification in TCP
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* implementing the essential parts of the Accurate ECN extension
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* https://tools.ietf.org/html/draft-ietf-tcpm-accurate-ecn-09
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_inet.h"
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#include "opt_inet6.h"
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#include "opt_tcpdebug.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/kernel.h>
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#include <sys/sysctl.h>
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#include <sys/malloc.h>
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#include <sys/mbuf.h>
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#include <sys/socket.h>
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#include <sys/socketvar.h>
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#include <machine/cpu.h>
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#include <vm/uma.h>
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#include <net/if.h>
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#include <net/if_var.h>
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#include <net/route.h>
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#include <net/vnet.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/in_var.h>
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#include <netinet/in_pcb.h>
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#include <netinet/ip_var.h>
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#include <netinet/ip6.h>
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#include <netinet/icmp6.h>
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#include <netinet6/nd6.h>
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#include <netinet6/ip6_var.h>
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#include <netinet6/in6_pcb.h>
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#include <netinet/tcp.h>
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#include <netinet/tcp_fsm.h>
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#include <netinet/tcp_seq.h>
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#include <netinet/tcp_var.h>
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#include <netinet/tcp_syncache.h>
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#include <netinet/tcp_timer.h>
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#include <netinet/tcpip.h>
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#include <netinet/tcp_ecn.h>
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/*
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* Process incoming SYN,ACK packet
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*/
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void
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tcp_ecn_input_syn_sent(struct tcpcb *tp, uint16_t thflags, int iptos)
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{
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if (V_tcp_do_ecn == 0)
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return;
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if ((V_tcp_do_ecn == 1) ||
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(V_tcp_do_ecn == 2)) {
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/* RFC3168 ECN handling */
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if ((thflags & (TH_CWR | TH_ECE)) == (0 | TH_ECE)) {
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tp->t_flags2 |= TF2_ECN_PERMIT;
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TCPSTAT_INC(tcps_ecn_shs);
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}
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} else
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/* decoding Accurate ECN according to table in section 3.1.1 */
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if ((V_tcp_do_ecn == 3) ||
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(V_tcp_do_ecn == 4)) {
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/*
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* on the SYN,ACK, process the AccECN
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* flags indicating the state the SYN
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* was delivered.
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* Reactions to Path ECN mangling can
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* come here.
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*/
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switch (thflags & (TH_AE | TH_CWR | TH_ECE)) {
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/* RFC3168 SYN */
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case (0|0|TH_ECE):
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tp->t_flags2 |= TF2_ECN_PERMIT;
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TCPSTAT_INC(tcps_ecn_shs);
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break;
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/* non-ECT SYN */
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case (0|TH_CWR|0):
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tp->t_flags2 |= TF2_ACE_PERMIT;
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tp->t_scep = 5;
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TCPSTAT_INC(tcps_ecn_shs);
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TCPSTAT_INC(tcps_ace_nect);
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break;
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/* ECT0 SYN */
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case (TH_AE|0|0):
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tp->t_flags2 |= TF2_ACE_PERMIT;
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tp->t_scep = 5;
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TCPSTAT_INC(tcps_ecn_shs);
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TCPSTAT_INC(tcps_ace_ect0);
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break;
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/* ECT1 SYN */
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case (0|TH_CWR|TH_ECE):
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tp->t_flags2 |= TF2_ACE_PERMIT;
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tp->t_scep = 5;
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TCPSTAT_INC(tcps_ecn_shs);
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TCPSTAT_INC(tcps_ace_ect1);
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break;
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/* CE SYN */
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case (TH_AE|TH_CWR|0):
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tp->t_flags2 |= TF2_ACE_PERMIT;
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tp->t_scep = 6;
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/*
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* reduce the IW to 2 MSS (to
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* account for delayed acks) if
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* the SYN,ACK was CE marked
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*/
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tp->snd_cwnd = 2 * tcp_maxseg(tp);
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TCPSTAT_INC(tcps_ecn_shs);
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TCPSTAT_INC(tcps_ace_nect);
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break;
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default:
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break;
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}
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/*
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* Set the AccECN Codepoints on
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* the outgoing <ACK> to the ECN
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* state of the <SYN,ACK>
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* according to table 3 in the
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* AccECN draft
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*/
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switch (iptos & IPTOS_ECN_MASK) {
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case (IPTOS_ECN_NOTECT):
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tp->t_rcep = 0b010;
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break;
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case (IPTOS_ECN_ECT0):
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tp->t_rcep = 0b100;
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break;
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case (IPTOS_ECN_ECT1):
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tp->t_rcep = 0b011;
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break;
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case (IPTOS_ECN_CE):
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tp->t_rcep = 0b110;
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break;
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}
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}
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}
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/*
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* Handle parallel SYN for ECN
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*/
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void
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tcp_ecn_input_parallel_syn(struct tcpcb *tp, uint16_t thflags, int iptos)
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{
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if (thflags & TH_ACK)
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return;
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if (V_tcp_do_ecn == 0)
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return;
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if ((V_tcp_do_ecn == 1) ||
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(V_tcp_do_ecn == 2)) {
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/* RFC3168 ECN handling */
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if ((thflags & (TH_CWR | TH_ECE)) == (TH_CWR | TH_ECE)) {
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tp->t_flags2 |= TF2_ECN_PERMIT;
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tp->t_flags2 |= TF2_ECN_SND_ECE;
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TCPSTAT_INC(tcps_ecn_shs);
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}
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} else
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if ((V_tcp_do_ecn == 3) ||
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(V_tcp_do_ecn == 4)) {
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/* AccECN handling */
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switch (thflags & (TH_AE | TH_CWR | TH_ECE)) {
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default:
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case (0|0|0):
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break;
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case (0|TH_CWR|TH_ECE):
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tp->t_flags2 |= TF2_ECN_PERMIT;
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tp->t_flags2 |= TF2_ECN_SND_ECE;
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TCPSTAT_INC(tcps_ecn_shs);
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break;
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case (TH_AE|TH_CWR|TH_ECE):
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tp->t_flags2 |= TF2_ACE_PERMIT;
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TCPSTAT_INC(tcps_ecn_shs);
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/*
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* Set the AccECN Codepoints on
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* the outgoing <ACK> to the ECN
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* state of the <SYN,ACK>
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* according to table 3 in the
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* AccECN draft
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*/
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switch (iptos & IPTOS_ECN_MASK) {
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case (IPTOS_ECN_NOTECT):
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tp->t_rcep = 0b010;
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break;
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case (IPTOS_ECN_ECT0):
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tp->t_rcep = 0b100;
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break;
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case (IPTOS_ECN_ECT1):
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tp->t_rcep = 0b011;
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break;
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case (IPTOS_ECN_CE):
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tp->t_rcep = 0b110;
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break;
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}
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break;
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}
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}
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}
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/*
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* TCP ECN processing.
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*/
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int
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tcp_ecn_input_segment(struct tcpcb *tp, uint16_t thflags, int iptos)
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{
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int delta_ace = 0;
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if (tp->t_flags2 & (TF2_ECN_PERMIT | TF2_ACE_PERMIT)) {
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switch (iptos & IPTOS_ECN_MASK) {
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case IPTOS_ECN_CE:
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TCPSTAT_INC(tcps_ecn_ce);
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break;
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case IPTOS_ECN_ECT0:
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TCPSTAT_INC(tcps_ecn_ect0);
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break;
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case IPTOS_ECN_ECT1:
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TCPSTAT_INC(tcps_ecn_ect1);
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break;
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}
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if (tp->t_flags2 & TF2_ACE_PERMIT) {
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if ((iptos & IPTOS_ECN_MASK) == IPTOS_ECN_CE)
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tp->t_rcep += 1;
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if (tp->t_flags2 & TF2_ECN_PERMIT) {
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delta_ace = (tcp_ecn_get_ace(thflags) + 8 -
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(tp->t_scep & 0x07)) & 0x07;
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tp->t_scep += delta_ace;
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} else {
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/*
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* process the final ACK of the 3WHS
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* see table 3 in draft-ietf-tcpm-accurate-ecn
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*/
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switch (tcp_ecn_get_ace(thflags)) {
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case 0b010:
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/* nonECT SYN or SYN,ACK */
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/* Fallthrough */
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case 0b011:
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/* ECT1 SYN or SYN,ACK */
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/* Fallthrough */
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case 0b100:
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/* ECT0 SYN or SYN,ACK */
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tp->t_scep = 5;
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break;
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case 0b110:
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/* CE SYN or SYN,ACK */
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tp->t_scep = 6;
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tp->snd_cwnd = 2 * tcp_maxseg(tp);
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break;
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default:
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/* mangled AccECN handshake */
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tp->t_scep = 5;
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break;
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}
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tp->t_flags2 |= TF2_ECN_PERMIT;
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}
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} else {
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/* RFC3168 ECN handling */
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if ((thflags & (TH_SYN | TH_ECE)) == TH_ECE)
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delta_ace = 1;
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if (thflags & TH_CWR) {
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tp->t_flags2 &= ~TF2_ECN_SND_ECE;
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tp->t_flags |= TF_ACKNOW;
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}
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if ((iptos & IPTOS_ECN_MASK) == IPTOS_ECN_CE)
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tp->t_flags2 |= TF2_ECN_SND_ECE;
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}
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/* Process a packet differently from RFC3168. */
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cc_ecnpkt_handler_flags(tp, thflags, iptos);
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}
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return delta_ace;
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}
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/*
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* Send ECN setup <SYN> packet header flags
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*/
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uint16_t
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tcp_ecn_output_syn_sent(struct tcpcb *tp)
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{
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uint16_t thflags = 0;
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if (V_tcp_do_ecn == 0)
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return thflags;
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if (V_tcp_do_ecn == 1) {
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/* Send a RFC3168 ECN setup <SYN> packet */
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if (tp->t_rxtshift >= 1) {
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if (tp->t_rxtshift <= V_tcp_ecn_maxretries)
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thflags = TH_ECE|TH_CWR;
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} else
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thflags = TH_ECE|TH_CWR;
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} else
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if (V_tcp_do_ecn == 3) {
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/* Send an Accurate ECN setup <SYN> packet */
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if (tp->t_rxtshift >= 1) {
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if (tp->t_rxtshift <= V_tcp_ecn_maxretries)
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thflags = TH_ECE|TH_CWR|TH_AE;
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} else
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thflags = TH_ECE|TH_CWR|TH_AE;
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}
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return thflags;
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}
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/*
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* output processing of ECN feature
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* returning IP ECN header codepoint
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*/
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int
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tcp_ecn_output_established(struct tcpcb *tp, uint16_t *thflags, int len, bool rxmit)
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{
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int ipecn = IPTOS_ECN_NOTECT;
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bool newdata;
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/*
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* If the peer has ECN, mark data packets with
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* ECN capable transmission (ECT).
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* Ignore pure control packets, retransmissions
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* and window probes.
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*/
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newdata = (len > 0 && SEQ_GEQ(tp->snd_nxt, tp->snd_max) &&
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!rxmit &&
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!((tp->t_flags & TF_FORCEDATA) && len == 1));
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/* RFC3168 ECN marking, only new data segments */
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if (newdata) {
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ipecn = IPTOS_ECN_ECT0;
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TCPSTAT_INC(tcps_ecn_ect0);
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}
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/*
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* Reply with proper ECN notifications.
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*/
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if (tp->t_flags2 & TF2_ACE_PERMIT) {
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*thflags &= ~(TH_AE|TH_CWR|TH_ECE);
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if (tp->t_rcep & 0x01)
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*thflags |= TH_ECE;
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if (tp->t_rcep & 0x02)
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*thflags |= TH_CWR;
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if (tp->t_rcep & 0x04)
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*thflags |= TH_AE;
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if (!(tp->t_flags2 & TF2_ECN_PERMIT)) {
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/*
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* here we process the final
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* ACK of the 3WHS
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*/
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if (tp->t_rcep == 0b110) {
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tp->t_rcep = 6;
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} else {
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tp->t_rcep = 5;
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}
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tp->t_flags2 |= TF2_ECN_PERMIT;
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}
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} else {
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if (newdata &&
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(tp->t_flags2 & TF2_ECN_SND_CWR)) {
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*thflags |= TH_CWR;
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tp->t_flags2 &= ~TF2_ECN_SND_CWR;
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}
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if (tp->t_flags2 & TF2_ECN_SND_ECE)
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*thflags |= TH_ECE;
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}
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return ipecn;
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}
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/*
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* Set up the ECN related tcpcb fields from
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* a syncache entry
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*/
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void
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tcp_ecn_syncache_socket(struct tcpcb *tp, struct syncache *sc)
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{
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if (sc->sc_flags & SCF_ECN_MASK) {
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switch (sc->sc_flags & SCF_ECN_MASK) {
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case SCF_ECN:
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tp->t_flags2 |= TF2_ECN_PERMIT;
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break;
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case SCF_ACE_N:
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/* Fallthrough */
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case SCF_ACE_0:
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/* Fallthrough */
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case SCF_ACE_1:
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tp->t_flags2 |= TF2_ACE_PERMIT;
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tp->t_scep = 5;
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tp->t_rcep = 5;
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break;
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case SCF_ACE_CE:
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tp->t_flags2 |= TF2_ACE_PERMIT;
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tp->t_scep = 6;
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tp->t_rcep = 6;
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break;
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/* undefined SCF codepoint */
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default:
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break;
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}
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}
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}
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/*
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* Process a <SYN> packets ECN information, and provide the
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* syncache with the relevant information.
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*/
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int
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tcp_ecn_syncache_add(uint16_t thflags, int iptos)
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{
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int scflags = 0;
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switch (thflags & (TH_AE|TH_CWR|TH_ECE)) {
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/* no ECN */
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case (0|0|0):
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break;
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/* legacy ECN */
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case (0|TH_CWR|TH_ECE):
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scflags = SCF_ECN;
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break;
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/* Accurate ECN */
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case (TH_AE|TH_CWR|TH_ECE):
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if ((V_tcp_do_ecn == 3) ||
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(V_tcp_do_ecn == 4)) {
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switch (iptos & IPTOS_ECN_MASK) {
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case IPTOS_ECN_CE:
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scflags = SCF_ACE_CE;
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break;
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case IPTOS_ECN_ECT0:
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scflags = SCF_ACE_0;
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break;
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case IPTOS_ECN_ECT1:
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scflags = SCF_ACE_1;
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break;
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case IPTOS_ECN_NOTECT:
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scflags = SCF_ACE_N;
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break;
|
|
}
|
|
} else
|
|
scflags = SCF_ECN;
|
|
break;
|
|
/* Default Case (section 3.1.2) */
|
|
default:
|
|
if ((V_tcp_do_ecn == 3) ||
|
|
(V_tcp_do_ecn == 4)) {
|
|
switch (iptos & IPTOS_ECN_MASK) {
|
|
case IPTOS_ECN_CE:
|
|
scflags = SCF_ACE_CE;
|
|
break;
|
|
case IPTOS_ECN_ECT0:
|
|
scflags = SCF_ACE_0;
|
|
break;
|
|
case IPTOS_ECN_ECT1:
|
|
scflags = SCF_ACE_1;
|
|
break;
|
|
case IPTOS_ECN_NOTECT:
|
|
scflags = SCF_ACE_N;
|
|
break;
|
|
}
|
|
}
|
|
break;
|
|
}
|
|
return scflags;
|
|
}
|
|
|
|
/*
|
|
* Set up the ECN information for the <SYN,ACK> from
|
|
* syncache information.
|
|
*/
|
|
uint16_t
|
|
tcp_ecn_syncache_respond(uint16_t thflags, struct syncache *sc)
|
|
{
|
|
if ((thflags & TH_SYN) &&
|
|
(sc->sc_flags & SCF_ECN_MASK)) {
|
|
switch (sc->sc_flags & SCF_ECN_MASK) {
|
|
case SCF_ECN:
|
|
thflags |= (0 | 0 | TH_ECE);
|
|
TCPSTAT_INC(tcps_ecn_shs);
|
|
break;
|
|
case SCF_ACE_N:
|
|
thflags |= (0 | TH_CWR | 0);
|
|
TCPSTAT_INC(tcps_ecn_shs);
|
|
TCPSTAT_INC(tcps_ace_nect);
|
|
break;
|
|
case SCF_ACE_0:
|
|
thflags |= (TH_AE | 0 | 0);
|
|
TCPSTAT_INC(tcps_ecn_shs);
|
|
TCPSTAT_INC(tcps_ace_ect0);
|
|
break;
|
|
case SCF_ACE_1:
|
|
thflags |= (0 | TH_ECE | TH_CWR);
|
|
TCPSTAT_INC(tcps_ecn_shs);
|
|
TCPSTAT_INC(tcps_ace_ect1);
|
|
break;
|
|
case SCF_ACE_CE:
|
|
thflags |= (TH_AE | TH_CWR | 0);
|
|
TCPSTAT_INC(tcps_ecn_shs);
|
|
TCPSTAT_INC(tcps_ace_ce);
|
|
break;
|
|
/* undefined SCF codepoint */
|
|
default:
|
|
break;
|
|
}
|
|
}
|
|
return thflags;
|
|
}
|
|
|
|
int
|
|
tcp_ecn_get_ace(uint16_t thflags)
|
|
{
|
|
int ace = 0;
|
|
|
|
if (thflags & TH_ECE)
|
|
ace += 1;
|
|
if (thflags & TH_CWR)
|
|
ace += 2;
|
|
if (thflags & TH_AE)
|
|
ace += 4;
|
|
return ace;
|
|
}
|