1 /* $KAME: ip_ecn.c,v 1.12 2002/01/07 11:34:47 kjc Exp $ */
2
3 /*-
4 * SPDX-License-Identifier: BSD-3-Clause
5 *
6 * Copyright (C) 1999 WIDE Project.
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the project nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 *
33 */
34 /*
35 * ECN consideration on tunnel ingress/egress operation.
36 * http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt
37 */
38
39 #include "opt_inet.h"
40 #include "opt_inet6.h"
41
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/mbuf.h>
45 #include <sys/errno.h>
46
47 #include <netinet/in.h>
48 #include <netinet/in_systm.h>
49 #include <netinet/ip.h>
50 #ifdef INET6
51 #include <netinet/ip6.h>
52 #endif
53
54 #include <netinet/ip_ecn.h>
55 #ifdef INET6
56 #include <netinet6/ip6_ecn.h>
57 #endif
58
59 /*
60 * ECN and TOS (or TCLASS) processing rules at tunnel encapsulation and
61 * decapsulation from RFC3168:
62 *
63 * Outer Hdr at Inner Hdr at
64 * Encapsulator Decapsulator
65 * Header fields: -------------------- ------------
66 * DS Field copied from inner hdr no change
67 * ECN Field constructed by (I) constructed by (E)
68 *
69 * ECN_ALLOWED (full functionality):
70 * (I) if the ECN field in the inner header is set to CE, then set the
71 * ECN field in the outer header to ECT(0).
72 * otherwise, copy the ECN field to the outer header.
73 *
74 * (E) if the ECN field in the outer header is set to CE and the ECN
75 * field of the inner header is not-ECT, drop the packet.
76 * if the ECN field in the inner header is set to ECT(0) or ECT(1)
77 * and the ECN field in the outer header is set to CE, then copy CE to
78 * the inner header. otherwise, make no change to the inner header.
79 *
80 * ECN_FORBIDDEN (limited functionality):
81 * (I) set the ECN field to not-ECT in the outer header.
82 *
83 * (E) if the ECN field in the outer header is set to CE, drop the packet.
84 * otherwise, make no change to the ECN field in the inner header.
85 *
86 * the drop rule is for backward compatibility and protection against
87 * erasure of CE.
88 */
89
90 /*
91 * modify outer ECN (TOS) field on ingress operation (tunnel encapsulation).
92 */
93 void
ip_ecn_ingress(int mode,uint8_t * outer,const uint8_t * inner)94 ip_ecn_ingress(int mode, uint8_t *outer, const uint8_t *inner)
95 {
96
97 if (!outer || !inner)
98 panic("NULL pointer passed to ip_ecn_ingress");
99
100 *outer = *inner;
101 switch (mode) {
102 case ECN_ALLOWED: /* ECN allowed */
103 /*
104 * full-functionality: if the inner is CE, set ECT(0)
105 * to the outer. otherwise, copy the ECN field.
106 */
107 if ((*inner & IPTOS_ECN_MASK) == IPTOS_ECN_CE)
108 *outer &= ~IPTOS_ECN_ECT1;
109 break;
110 case ECN_FORBIDDEN: /* ECN forbidden */
111 /*
112 * limited-functionality: set not-ECT to the outer
113 */
114 *outer &= ~IPTOS_ECN_MASK;
115 break;
116 case ECN_NOCARE: /* no consideration to ECN */
117 break;
118 }
119 }
120
121 /*
122 * modify inner ECN (TOS) field on egress operation (tunnel decapsulation).
123 * the caller should drop the packet if the return value is 0.
124 */
125 int
ip_ecn_egress(int mode,const uint8_t * outer,uint8_t * inner)126 ip_ecn_egress(int mode, const uint8_t *outer, uint8_t *inner)
127 {
128
129 if (!outer || !inner)
130 panic("NULL pointer passed to ip_ecn_egress");
131
132 switch (mode) {
133 case ECN_ALLOWED:
134 /*
135 * full-functionality: if the outer is CE and the inner is
136 * not-ECT, should drop it. otherwise, copy CE.
137 */
138 if ((*outer & IPTOS_ECN_MASK) == IPTOS_ECN_CE) {
139 if ((*inner & IPTOS_ECN_MASK) == IPTOS_ECN_NOTECT)
140 return (0);
141 *inner |= IPTOS_ECN_CE;
142 }
143 break;
144 case ECN_FORBIDDEN: /* ECN forbidden */
145 /*
146 * limited-functionality: if the outer is CE, should drop it.
147 * otherwise, leave the inner.
148 */
149 if ((*outer & IPTOS_ECN_MASK) == IPTOS_ECN_CE)
150 return (0);
151 break;
152 case ECN_NOCARE: /* no consideration to ECN */
153 break;
154 }
155 return (1);
156 }
157
158 #ifdef INET6
159 void
ip6_ecn_ingress(int mode,uint32_t * outer,const uint32_t * inner)160 ip6_ecn_ingress(int mode, uint32_t *outer, const uint32_t *inner)
161 {
162 uint8_t outer8, inner8;
163
164 if (!outer || !inner)
165 panic("NULL pointer passed to ip6_ecn_ingress");
166
167 inner8 = (ntohl(*inner) >> 20) & 0xff;
168 ip_ecn_ingress(mode, &outer8, &inner8);
169 *outer &= ~htonl(0xff << 20);
170 *outer |= htonl((uint32_t)outer8 << 20);
171 }
172
173 int
ip6_ecn_egress(int mode,const uint32_t * outer,uint32_t * inner)174 ip6_ecn_egress(int mode, const uint32_t *outer, uint32_t *inner)
175 {
176 uint8_t outer8, inner8, oinner8;
177
178 if (!outer || !inner)
179 panic("NULL pointer passed to ip6_ecn_egress");
180
181 outer8 = (ntohl(*outer) >> 20) & 0xff;
182 inner8 = oinner8 = (ntohl(*inner) >> 20) & 0xff;
183 if (ip_ecn_egress(mode, &outer8, &inner8) == 0)
184 return (0);
185 if (inner8 != oinner8) {
186 *inner &= ~htonl(0xff << 20);
187 *inner |= htonl((uint32_t)inner8 << 20);
188 }
189 return (1);
190 }
191 #endif
192