1 /* $OpenBSD: ip_ecn.c,v 1.7 2014/12/19 17:14:40 tedu Exp $ */ 2 /* $KAME: ip_ecn.c,v 1.9 2000/10/01 12:44:48 itojun Exp $ */ 3 4 /* 5 * Copyright (C) 1999 WIDE Project. 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. Neither the name of the project nor the names of its contributors 17 * may be used to endorse or promote products derived from this software 18 * without specific prior written permission. 19 * 20 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND 21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE 24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30 * SUCH DAMAGE. 31 * 32 */ 33 /* 34 * ECN consideration on tunnel ingress/egress operation. 35 * http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt 36 */ 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/mbuf.h> 41 42 #include <netinet/in.h> 43 #include <netinet/ip.h> 44 45 #ifdef INET6 46 #include <netinet/ip6.h> 47 #endif 48 49 #include <netinet/ip_ecn.h> 50 51 /* 52 * ECN and TOS (or TCLASS) processing rules at tunnel encapsulation and 53 * decapsulation from RFC3168: 54 * 55 * Outer Hdr at Inner Hdr at 56 * Encapsulator Decapsulator 57 * Header fields: -------------------- ------------ 58 * DS Field copied from inner hdr no change 59 * ECN Field constructed by (I) constructed by (E) 60 * 61 * ECN_ALLOWED (full functionality): 62 * (I) if the ECN field in the inner header is set to CE, then set the 63 * ECN field in the outer header to ECT(0). 64 * otherwise, copy the ECN field to the outer header. 65 * 66 * (E) if the ECN field in the outer header is set to CE and the ECN 67 * field of the inner header is not-ECT, drop the packet. 68 * if the ECN field in the inner header is set to ECT(0) or ECT(1) 69 * and the ECN field in the outer header is set to CE, then copy CE to 70 * the inner header. otherwise, make no change to the inner header. 71 * 72 * ECN_FORBIDDEN (limited functionality): 73 * (I) set the ECN field to not-ECT in the outer header. 74 * 75 * (E) if the ECN field in the outer header is set to CE, drop the packet. 76 * otherwise, make no change to the ECN field in the inner header. 77 * 78 * the drop rule is for backward compatibility and protection against 79 * erasure of CE. 80 */ 81 82 /* 83 * modify outer ECN (TOS) field on ingress operation (tunnel encapsulation). 84 * call it after you've done the default initialization/copy for the outer. 85 */ 86 void 87 ip_ecn_ingress(mode, outer, inner) 88 int mode; 89 u_int8_t *outer; 90 u_int8_t *inner; 91 { 92 if (!outer || !inner) 93 panic("NULL pointer passed to ip_ecn_ingress"); 94 95 *outer = *inner; 96 switch (mode) { 97 case ECN_ALLOWED: /* ECN allowed */ 98 case ECN_ALLOWED_IPSEC: 99 /* 100 * full-functionality: if the inner is CE, set ECT(0) 101 * to the outer. otherwise, copy the ECN field. 102 */ 103 if ((*inner & IPTOS_ECN_MASK) == IPTOS_ECN_CE) 104 *outer &= ~IPTOS_ECN_ECT1; 105 break; 106 case ECN_FORBIDDEN: /* ECN forbidden */ 107 /* 108 * limited-functionality: set not-ECT to the outer 109 */ 110 *outer &= ~IPTOS_ECN_MASK; 111 break; 112 case ECN_NOCARE: /* no consideration to ECN */ 113 break; 114 } 115 } 116 117 /* 118 * modify inner ECN (TOS) field on egress operation (tunnel decapsulation). 119 * call it after you've done the default initialization/copy for the inner. 120 * the caller should drop the packet if the return value is 0. 121 */ 122 int 123 ip_ecn_egress(mode, outer, inner) 124 int mode; 125 u_int8_t *outer; 126 u_int8_t *inner; 127 { 128 if (!outer || !inner) 129 panic("NULL pointer passed to ip_ecn_egress"); 130 131 switch (mode) { 132 case ECN_ALLOWED: 133 case ECN_ALLOWED_IPSEC: 134 /* 135 * full-functionality: if the outer is CE and the inner is 136 * not-ECT, should drop it. otherwise, copy CE. 137 * However, according to RFC4301, we should just leave the 138 * inner as non-ECT for IPsec. 139 */ 140 if ((*outer & IPTOS_ECN_MASK) == IPTOS_ECN_CE) { 141 if ((*inner & IPTOS_ECN_MASK) == IPTOS_ECN_NOTECT) { 142 if (mode == ECN_ALLOWED_IPSEC) 143 return (1); 144 else 145 return (0); 146 } 147 *inner |= IPTOS_ECN_CE; 148 } 149 break; 150 case ECN_FORBIDDEN: /* ECN forbidden */ 151 /* 152 * limited-functionality: if the outer is CE, should drop it. 153 * otherwise, leave the inner. 154 */ 155 if ((*outer & IPTOS_ECN_MASK) == IPTOS_ECN_CE) 156 return (0); 157 break; 158 case ECN_NOCARE: /* no consideration to ECN */ 159 break; 160 } 161 return (1); 162 } 163