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/* $OpenBSD: ip_ecn.c,v 1.9 2018/11/14 23:55:04 dlg Exp $ */
/* $KAME: ip_ecn.c,v 1.9 2000/10/01 12:44:48 itojun Exp $ */
/*
* Copyright (C) 1999 WIDE Project.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the project nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*/
/*
* ECN consideration on tunnel ingress/egress operation.
* http://www.aciri.org/floyd/papers/draft-ipsec-ecn-00.txt
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/mbuf.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#ifdef INET6
#include <netinet/ip6.h>
#endif
#include <netinet/ip_ecn.h>
/*
* ECN and TOS (or TCLASS) processing rules at tunnel encapsulation and
* decapsulation from RFC3168:
*
* Outer Hdr at Inner Hdr at
* Encapsulator Decapsulator
* Header fields: -------------------- ------------
* DS Field copied from inner hdr no change
* ECN Field constructed by (I) constructed by (E)
*
* ECN_ALLOWED (full functionality):
* (I) if the ECN field in the inner header is set to CE, then set the
* ECN field in the outer header to ECT(0).
* otherwise, copy the ECN field to the outer header.
*
* (E) if the ECN field in the outer header is set to CE and the ECN
* field of the inner header is not-ECT, drop the packet.
* if the ECN field in the inner header is set to ECT(0) or ECT(1)
* and the ECN field in the outer header is set to CE, then copy CE to
* the inner header. otherwise, make no change to the inner header.
*
* ECN_FORBIDDEN (limited functionality):
* (I) set the ECN field to not-ECT in the outer header.
*
* (E) if the ECN field in the outer header is set to CE, drop the packet.
* otherwise, make no change to the ECN field in the inner header.
*
* the drop rule is for backward compatibility and protection against
* erasure of CE.
*/
/*
* modify outer ECN (TOS) field on ingress operation (tunnel encapsulation).
* call it after you've done the default initialization/copy for the outer.
*/
void
ip_ecn_ingress(int mode, u_int8_t *outer, u_int8_t *inner)
{
if (!outer || !inner)
panic("NULL pointer passed to ip_ecn_ingress");
*outer = *inner;
switch (mode) {
case ECN_ALLOWED: /* ECN allowed */
case ECN_ALLOWED_IPSEC:
/*
* full-functionality: if the inner is CE, set ECT(0)
* to the outer. otherwise, copy the ECN field.
*/
if ((*inner & IPTOS_ECN_MASK) == IPTOS_ECN_CE)
*outer &= ~IPTOS_ECN_ECT1;
break;
case ECN_FORBIDDEN: /* ECN forbidden */
/*
* limited-functionality: set not-ECT to the outer
*/
*outer &= ~IPTOS_ECN_MASK;
break;
case ECN_NOCARE: /* no consideration to ECN */
break;
}
}
/*
* modify inner ECN (TOS) field on egress operation (tunnel decapsulation).
* call it after you've done the default initialization/copy for the inner.
* the caller should drop the packet if the return value is 0.
*/
int
ip_ecn_egress(int mode, u_int8_t *outer, u_int8_t *inner)
{
if (!outer || !inner)
panic("NULL pointer passed to ip_ecn_egress");
switch (mode) {
case ECN_ALLOWED:
case ECN_ALLOWED_IPSEC:
/*
* full-functionality: if the outer is CE and the inner is
* not-ECT, should drop it. otherwise, copy CE.
* However, according to RFC4301, we should just leave the
* inner as non-ECT for IPsec.
*/
if ((*outer & IPTOS_ECN_MASK) == IPTOS_ECN_CE) {
if ((*inner & IPTOS_ECN_MASK) == IPTOS_ECN_NOTECT) {
if (mode == ECN_ALLOWED_IPSEC)
return (1);
else
return (0);
}
*inner |= IPTOS_ECN_CE;
}
break;
case ECN_FORBIDDEN: /* ECN forbidden */
/*
* limited-functionality: if the outer is CE, should drop it.
* otherwise, leave the inner.
*/
if ((*outer & IPTOS_ECN_MASK) == IPTOS_ECN_CE)
return (0);
break;
case ECN_NOCARE: /* no consideration to ECN */
break;
}
return (1);
}
/*
* Patch the checksum with the difference between the old and new tos.
* The patching is based on what pf_patch_8() and pf_cksum_fixkup() do,
* but they're in pf, so we can't rely on them being available.
*/
void
ip_tos_patch(struct ip *ip, uint8_t tos)
{
uint16_t old;
uint16_t new;
uint32_t x;
old = htons(ip->ip_tos);
new = htons(tos);
ip->ip_tos = tos;
x = ip->ip_sum + old - new;
ip->ip_sum = (x) + (x >> 16);
}
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