system/freebsd-src
system/freebsd-src
1
0
Fork 0
mirror of https://github.com/freebsd/freebsd-src synced 2024-09-06 09:10:28 +00:00
Code Issues Packages Projects Releases Wiki Activity

Follow RFC 4443 p2.2 and always use own addresses for reflected ICMPv6

Browse source 
datagrams.

Previously destination address from original datagram was used. That
looked confusing, especially in the traceroute6 output.
Also honor IPSTEALTH kernel option and do TTL/HLIM decrementing only
when stealth mode is disabled.

Reported by:	Marco van Tol <marco at tols org>
Reviewed by:	melifaro
MFC after:	2 weeks
Sponsored by:	Yandex LLC
Differential Revision:	https://reviews.freebsd.org/D22631
This commit is contained in:
Andrey V. Elsukov 2019-12-12 13:28:46 +00:00
parent e63adc105d
commit 2873980947
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=355650
2 changed files with 67 additions and 14 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

1
sys/modules/ipfw_nat64/Makefile
View file

@ -7,6 +7,7 @@ SRCS= ip_fw_nat64.c nat64_translate.c
SRCS+= nat64clat.c nat64clat_control.c
SRCS+= nat64lsn.c nat64lsn_control.c
SRCS+= nat64stl.c nat64stl_control.c
SRCS+= opt_ipstealth.h
CFLAGS+= -I${SRCTOP}/sys/contrib/ck/include

80
sys/netpfil/ipfw/nat64/nat64_translate.c
View file

@ -29,6 +29,8 @@
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include "opt_ipstealth.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/counter.h>
@ -101,14 +103,39 @@ static const struct nat64_methods nat64_direct = {
.output = nat64_direct_output,
.output_one = nat64_direct_output_one
};
VNET_DEFINE_STATIC(const struct nat64_methods *, nat64out) = &nat64_netisr;
#define V_nat64out VNET(nat64out)
/* These variables should be initialized explicitly on module loading */
VNET_DEFINE_STATIC(const struct nat64_methods *, nat64out);
VNET_DEFINE_STATIC(const int *, nat64ipstealth);
VNET_DEFINE_STATIC(const int *, nat64ip6stealth);
#define V_nat64out VNET(nat64out)
#define V_nat64ipstealth VNET(nat64ipstealth)
#define V_nat64ip6stealth VNET(nat64ip6stealth)
static const int stealth_on = 1;
#ifndef IPSTEALTH
static const int stealth_off = 0;
#endif
void
nat64_set_output_method(int direct)
{
V_nat64out = direct != 0 ? &nat64_direct: &nat64_netisr;
if (direct != 0) {
V_nat64out = &nat64_direct;
#ifdef IPSTEALTH
/* Honor corresponding variables, if IPSTEALTH is defined */
V_nat64ipstealth = &V_ipstealth;
V_nat64ip6stealth = &V_ip6stealth;
#else
/* otherwise we need to decrement HLIM/TTL for direct case */
V_nat64ipstealth = V_nat64ip6stealth = &stealth_off;
#endif
} else {
V_nat64out = &nat64_netisr;
/* Leave TTL/HLIM decrementing to forwarding code */
V_nat64ipstealth = V_nat64ip6stealth = &stealth_on;
}
}
int
@ -486,8 +513,7 @@ nat64_init_ip4hdr(const struct ip6_hdr *ip6, const struct ip6_frag *frag,
ip->ip_tos = (ntohl(ip6->ip6_flow) >> 20) & 0xff;
ip->ip_len = htons(sizeof(*ip) + plen);
ip->ip_ttl = ip6->ip6_hlim;
/* Forwarding code will decrement TTL for netisr based output. */
if (V_nat64out == &nat64_direct)
if (*V_nat64ip6stealth == 0)
ip->ip_ttl -= IPV6_HLIMDEC;
ip->ip_sum = 0;
ip->ip_p = (proto == IPPROTO_ICMPV6) ? IPPROTO_ICMP: proto;
@ -623,18 +649,18 @@ nat64_icmp6_reflect(struct mbuf *m, uint8_t type, uint8_t code, uint32_t mtu,
struct icmp6_hdr *icmp6;
struct ip6_hdr *ip6, *oip6;
struct mbuf *n;
int len, plen;
int len, plen, proto;
len = 0;
plen = nat64_getlasthdr(m, &len);
if (plen < 0) {
proto = nat64_getlasthdr(m, &len);
if (proto < 0) {
DPRINTF(DP_DROPS, "mbuf isn't contigious");
goto freeit;
}
/*
* Do not send ICMPv6 in reply to ICMPv6 errors.
*/
if (plen == IPPROTO_ICMPV6) {
if (proto == IPPROTO_ICMPV6) {
if (m->m_len < len + sizeof(*icmp6)) {
DPRINTF(DP_DROPS, "mbuf isn't contigious");
goto freeit;
@ -646,6 +672,21 @@ nat64_icmp6_reflect(struct mbuf *m, uint8_t type, uint8_t code, uint32_t mtu,
"ICMPv6 errors");
goto freeit;
}
/*
* If there are extra headers between IPv6 and ICMPv6,
* strip off them.
*/
if (len > sizeof(struct ip6_hdr)) {
/*
* NOTE: ipfw_chk already did m_pullup() and it is
* expected that data is contigious from the start
* of IPv6 header up to the end of ICMPv6 header.
*/
bcopy(mtod(m, caddr_t),
mtodo(m, len - sizeof(struct ip6_hdr)),
sizeof(struct ip6_hdr));
m_adj(m, len - sizeof(struct ip6_hdr));
}
}
/*
if (icmp6_ratelimit(&ip6->ip6_src, type, code))
@ -687,7 +728,19 @@ nat64_icmp6_reflect(struct mbuf *m, uint8_t type, uint8_t code, uint32_t mtu,
n->m_len = n->m_pkthdr.len = sizeof(struct ip6_hdr) + plen;
oip6 = mtod(n, struct ip6_hdr *);
oip6->ip6_src = ip6->ip6_dst;
/*
* Make IPv6 source address selection for reflected datagram.
* nat64_check_ip6() doesn't allow scoped addresses, therefore
* we use zero scopeid.
*/
if (in6_selectsrc_addr(M_GETFIB(n), &ip6->ip6_src, 0,
n->m_pkthdr.rcvif, &oip6->ip6_src, NULL) != 0) {
/*
* Failed to find proper source address, drop the packet.
*/
m_freem(n);
goto freeit;
}
oip6->ip6_dst = ip6->ip6_src;
oip6->ip6_nxt = IPPROTO_ICMPV6;
oip6->ip6_flow = 0;
@ -1182,7 +1235,7 @@ nat64_do_handle_ip4(struct mbuf *m, struct in6_addr *saddr,
ip = mtod(m, struct ip*);
if (ip->ip_ttl <= IPTTLDEC) {
if (*V_nat64ipstealth == 0 && ip->ip_ttl <= IPTTLDEC) {
nat64_icmp_reflect(m, ICMP_TIMXCEED,
ICMP_TIMXCEED_INTRANS, 0, &cfg->stats, logdata);
return (NAT64RETURN);
@ -1229,8 +1282,7 @@ nat64_do_handle_ip4(struct mbuf *m, struct in6_addr *saddr,
ip6.ip6_flow = htonl(ip->ip_tos << 20);
ip6.ip6_vfc |= IPV6_VERSION;
ip6.ip6_hlim = ip->ip_ttl;
/* Forwarding code will decrement TTL for netisr based output. */
if (V_nat64out == &nat64_direct)
if (*V_nat64ipstealth == 0)
ip6.ip6_hlim -= IPTTLDEC;
ip6.ip6_plen = htons(plen);
ip6.ip6_nxt = (proto == IPPROTO_ICMP) ? IPPROTO_ICMPV6: proto;
@ -1533,7 +1585,7 @@ nat64_do_handle_ip6(struct mbuf *m, uint32_t aaddr, uint16_t aport,
return (NAT64MFREE);
}
if (ip6->ip6_hlim <= IPV6_HLIMDEC) {
if (*V_nat64ip6stealth == 0 && ip6->ip6_hlim <= IPV6_HLIMDEC) {
nat64_icmp6_reflect(m, ICMP6_TIME_EXCEEDED,
ICMP6_TIME_EXCEED_TRANSIT, 0, &cfg->stats, logdata);
return (NAT64RETURN);