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freebsd/sys/netinet/ip_nat.c
Darren Reed e10102a12a Import version 3.2alpha7
1997-05-25 15:50:46 +00:00

1086 lines
25 KiB
C
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/*
* (C)opyright 1995-1996 by Darren Reed.
*
* Redistribution and use in source and binary forms are permitted
* provided that this notice is preserved and due credit is given
* to the original author and the contributors.
*
* Added redirect stuff and a LOT of bug fixes. (mcn@EnGarde.com)
*/
#if !defined(lint) && defined(LIBC_SCCS)
static char sccsid[] = "@(#)ip_nat.c 1.11 6/5/96 (C) 1995 Darren Reed";
static char rcsid[] = "$Id: ip_nat.c,v 2.0.2.18 1997/05/24 07:34:44 darrenr Exp $";
#endif
#if defined(__FreeBSD__) && defined(KERNEL) && !defined(_KERNEL)
#define _KERNEL
#endif
#if !defined(_KERNEL) && !defined(KERNEL)
# include <stdio.h>
# include <string.h>
# include <stdlib.h>
#endif
#include <sys/errno.h>
#include <sys/types.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/file.h>
#if defined(KERNEL) && (__FreeBSD_version >= 220000)
# include <sys/filio.h>
# include <sys/fnctl.h>
#else
# include <sys/ioctl.h>
#endif
#include <sys/fcntl.h>
#include <sys/uio.h>
#include <sys/protosw.h>
#include <sys/socket.h>
#ifdef _KERNEL
# include <sys/systm.h>
#endif
#if !defined(__SVR4) && !defined(__svr4__)
# include <sys/mbuf.h>
#else
# include <sys/filio.h>
# include <sys/byteorder.h>
# include <sys/dditypes.h>
# include <sys/stream.h>
# include <sys/kmem.h>
#endif
#if __FreeBSD_version >= 300000
# include <sys/queue.h>
#endif
#include <net/if.h>
#if __FreeBSD_version >= 300000
# include <net/if_var.h>
#endif
#ifdef sun
#include <net/af.h>
#endif
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#ifdef RFC1825
#include <vpn/md5.h>
#include <vpn/ipsec.h>
extern struct ifnet vpnif;
#endif
#include <netinet/ip_var.h>
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <netinet/tcpip.h>
#include <netinet/ip_icmp.h>
#include "netinet/ip_compat.h"
#include "netinet/ip_fil.h"
#include "netinet/ip_proxy.h"
#include "netinet/ip_nat.h"
#include "netinet/ip_frag.h"
#include "netinet/ip_state.h"
#ifndef MIN
#define MIN(a,b) (((a)<(b))?(a):(b))
#endif
#undef SOCKADDR_IN
#define SOCKADDR_IN struct sockaddr_in
nat_t *nat_table[2][NAT_SIZE], *nat_instances = NULL;
ipnat_t *nat_list = NULL;
u_long fr_defnatage = 1200;
natstat_t nat_stats;
#if SOLARIS && defined(_KERNEL)
extern kmutex_t ipf_nat;
extern kmutex_t ipf_natfrag;
#endif
static int flush_nattable __P((void)), clear_natlist __P((void));
void fix_outcksum(sp, n)
u_short *sp;
u_long n;
{
register u_short sumshort;
register u_long sum1;
#ifdef sparc
sum1 = (~(*sp)) & 0xffff;
#else
sum1 = (~ntohs(*sp)) & 0xffff;
#endif
sum1 += (n);
sum1 = (sum1 >> 16) + (sum1 & 0xffff);
/* Again */
sum1 = (sum1 >> 16) + (sum1 & 0xffff);
sumshort = ~(u_short)sum1;
*(sp) = htons(sumshort);
}
void fix_incksum(sp, n)
u_short *sp;
u_long n;
{
register u_short sumshort;
register u_long sum1;
#ifdef sparc
sum1 = (~(*sp)) & 0xffff;
#else
sum1 = (~ntohs(*sp)) & 0xffff;
#endif
sum1 += ~(n) & 0xffff;
sum1 = (sum1 >> 16) + (sum1 & 0xffff);
/* Again */
sum1 = (sum1 >> 16) + (sum1 & 0xffff);
sumshort = ~(u_short)sum1;
*(sp) = htons(sumshort);
}
/*
* How the NAT is organised and works.
*
* Inside (interface y) NAT Outside (interface x)
* -------------------- -+- -------------------------------------
* Packet going | out, processsed by ip_natout() for x
* ------------> | ------------>
* src=10.1.1.1 | src=192.1.1.1
* |
* | in, processed by ip_natin() for x
* <------------ | <------------
* dst=10.1.1.1 | dst=192.1.1.1
* -------------------- -+- -------------------------------------
* ip_natout() - changes ip_src and if required, sport
* - creates a new mapping, if required.
* ip_natin() - changes ip_dst and if required, dport
*
* In the NAT table, internal source is recorded as "in" and externally
* seen as "out".
*/
/*
* Handle ioctls which manipulate the NAT.
*/
int nat_ioctl(data, cmd, mode)
caddr_t data;
int cmd, mode;
{
register ipnat_t *nat, *n = NULL, **np = NULL;
ipnat_t natd;
int error = 0, ret, s;
/*
* For add/delete, look to see if the NAT entry is already present
*/
MUTEX_ENTER(&ipf_nat);
SPLNET(s);
if ((cmd == SIOCADNAT) || (cmd == SIOCRMNAT)) {
IRCOPY(data, (char *)&natd, sizeof(natd));
nat = &natd;
for (np = &nat_list; (n = *np); np = &n->in_next)
if (!bcmp((char *)&nat->in_flags, (char *)&n->in_flags,
IPN_CMPSIZ))
break;
}
switch (cmd)
{
case SIOCADNAT :
if (!(mode & FWRITE)) {
error = EPERM;
break;
}
if (n) {
error = EEXIST;
break;
}
KMALLOC(n, ipnat_t *, sizeof(*n));
if (n == NULL) {
error = ENOMEM;
break;
}
IRCOPY((char *)data, (char *)n, sizeof(*n));
n->in_ifp = (void *)GETUNIT(n->in_ifname);
n->in_apr = ap_match(n->in_p, n->in_plabel);
n->in_next = *np;
n->in_use = 0;
n->in_space = ~(0xffffffff & ntohl(n->in_outmsk));
if (n->in_space) /* lose 2: broadcast + network address */
n->in_space -= 2;
else
n->in_space = 1; /* single IP# mapping */
if (n->in_outmsk != 0xffffffff)
n->in_nip = ntohl(n->in_outip) + 1;
else
n->in_nip = ntohl(n->in_outip);
if (n->in_redir & NAT_MAP) {
n->in_pnext = ntohs(n->in_pmin);
/*
* Multiply by the number of ports made available.
*/
if (ntohs(n->in_pmax) > ntohs(n->in_pmin))
n->in_space *= (ntohs(n->in_pmax) -
ntohs(n->in_pmin));
}
/* Otherwise, these fields are preset */
*np = n;
nat_stats.ns_rules++;
break;
case SIOCRMNAT :
if (!(mode & FWRITE)) {
error = EPERM;
break;
}
if (!n) {
error = ESRCH;
break;
}
*np = n->in_next;
if (!n->in_use) {
if (n->in_apr)
ap_free(n->in_apr);
KFREE(n);
nat_stats.ns_rules--;
} else {
n->in_flags |= IPN_DELETE;
n->in_next = NULL;
}
break;
case SIOCGNATS :
nat_stats.ns_table[0] = nat_table[0];
nat_stats.ns_table[1] = nat_table[1];
nat_stats.ns_list = nat_list;
IWCOPY((char *)&nat_stats, (char *)data, sizeof(nat_stats));
break;
case SIOCGNATL :
{
natlookup_t nl;
IRCOPY((char *)data, (char *)&nl, sizeof(nl));
if (nat_lookupredir(&nl))
IWCOPY((char *)&nl, (char *)data, sizeof(nl));
else
error = ESRCH;
break;
}
case SIOCFLNAT :
if (!(mode & FWRITE)) {
error = EPERM;
break;
}
ret = flush_nattable();
IWCOPY((caddr_t)&ret, data, sizeof(ret));
break;
case SIOCCNATL :
if (!(mode & FWRITE)) {
error = EPERM;
break;
}
ret = clear_natlist();
IWCOPY((caddr_t)&ret, data, sizeof(ret));
break;
case FIONREAD :
#ifdef IPFILTER_LOG
*(int *)data = iplused[IPL_LOGNAT];
#endif
break;
}
SPLX(s);
MUTEX_EXIT(&ipf_nat);
return error;
}
static void nat_delete(natd)
struct nat *natd;
{
register struct nat **natp, *nat;
struct ipnat *ipn;
for (natp = natd->nat_hstart[0]; (nat = *natp);
natp = &nat->nat_hnext[0])
if (nat == natd) {
*natp = nat->nat_hnext[0];
break;
}
for (natp = natd->nat_hstart[1]; (nat = *natp);
natp = &nat->nat_hnext[1])
if (nat == natd) {
*natp = nat->nat_hnext[1];
break;
}
if ((ipn = natd->nat_ptr)) {
ipn->in_space++;
ipn->in_use--;
if (!ipn->in_use && (ipn->in_flags & IPN_DELETE)) {
if (ipn->in_apr)
ap_free(ipn->in_apr);
KFREE(ipn);
nat_stats.ns_rules--;
}
}
MUTEX_ENTER(&ipf_natfrag);
if (nat->nat_frag && nat->nat_frag->ipfr_data == nat)
nat->nat_frag->ipfr_data = NULL;
MUTEX_EXIT(&ipf_natfrag);
KFREE(natd);
}
/*
* flush_nattable - clear the NAT table of all mapping entries.
*/
static int flush_nattable()
{
register nat_t *nat, **natp;
register int j = 0;
/*
* Everything will be deleted, so lets just make it the deletions
* quicker.
*/
bzero((char *)nat_table[0], sizeof(nat_table[0]));
bzero((char *)nat_table[1], sizeof(nat_table[1]));
for (natp = &nat_instances; (nat = *natp); ) {
*natp = nat->nat_next;
nat_delete(nat);
j++;
}
return j;
}
/*
* clear_natlist - delete all entries in the active NAT mapping list.
*/
static int clear_natlist()
{
register ipnat_t *n, **np = &nat_list;
int i = 0;
while ((n = *np)) {
*np = n->in_next;
if (!n->in_use) {
if (n->in_apr)
ap_free(n->in_apr);
KFREE(n);
nat_stats.ns_rules--;
i++;
} else {
n->in_flags |= IPN_DELETE;
n->in_next = NULL;
}
}
nat_stats.ns_inuse = 0;
return i;
}
/*
* Create a new NAT table entry.
*/
nat_t *nat_new(np, ip, fin, flags, direction)
ipnat_t *np;
ip_t *ip;
fr_info_t *fin;
u_short flags;
int direction;
{
register u_long sum1, sum2, sumd;
u_short port = 0, sport = 0, dport = 0, nport = 0;
struct in_addr in;
tcphdr_t *tcp = NULL;
nat_t *nat, **natp;
u_short nflags;
nflags = flags & np->in_flags;
if (flags & IPN_TCPUDP) {
tcp = (tcphdr_t *)fin->fin_dp;
sport = tcp->th_sport;
dport = tcp->th_dport;
}
/* Give me a new nat */
KMALLOC(nat, nat_t *, sizeof(*nat));
if (nat == NULL)
return NULL;
bzero((char *)nat, sizeof(*nat));
nat->nat_flags = flags;
/*
* Search the current table for a match.
*/
if (direction == NAT_OUTBOUND) {
#if SOLARIS
ill_t *ill = fin->fin_ifp;
#else
struct ifnet *ifp = fin->fin_ifp;
#endif
/*
* If it's an outbound packet which doesn't match any existing
* record, then create a new port
*/
do {
port = 0;
in.s_addr = np->in_nip;
if (!in.s_addr && (np->in_outmsk == 0xffffffff)) {
#if SOLARIS
in.s_addr = ill->ill_ipif->ipif_local_addr;
#else
struct ifaddr *ifa;
struct sockaddr_in *sin;
# if (__FreeBSD_version >= 300000)
ifa = TAILQ_FIRST(&ifp->if_addrhead);
# else
# ifdef __NetBSD__
ifa = ifp->if_addrlist.tqh_first;
# else
ifa = ifp->if_addrlist;
# endif
# endif
# if BSD < 199306
sin = (SOCKADDR_IN *)&ifa->ifa_addr;
# else
sin = (SOCKADDR_IN *)ifa->ifa_addr;
while (sin && ifa &&
sin->sin_family != AF_INET) {
# if (__FreeBSD_version >= 300000)
ifa = TAILQ_NEXT(ifa, ifa_link);
# else
# ifdef __NetBSD__
ifa = ifa->ifa_list.tqe_next;
# else
ifa = ifa->ifa_next;
# endif
# endif
sin = (SOCKADDR_IN *)ifa->ifa_addr;
}
if (!ifa)
sin = NULL;
if (!sin) {
KFREE(nat);
return NULL;
}
# endif
in = sin->sin_addr;
in.s_addr = ntohl(in.s_addr);
#endif
}
if (nflags & IPN_TCPUDP) {
port = htons(np->in_pnext++);
if (np->in_pnext >= ntohs(np->in_pmax)) {
np->in_pnext = ntohs(np->in_pmin);
np->in_space--;
if (np->in_outmsk != 0xffffffff)
np->in_nip++;
}
} else if (np->in_outmsk != 0xffffffff) {
np->in_space--;
np->in_nip++;
}
if (!port && (flags & IPN_TCPUDP))
port = sport;
if ((np->in_nip & ntohl(np->in_outmsk)) >
ntohl(np->in_outip))
np->in_nip = ntohl(np->in_outip) + 1;
} while (nat_inlookup(fin->fin_ifp, flags, ip->ip_dst,
dport, in, port));
/* Setup the NAT table */
nat->nat_inip = ip->ip_src;
nat->nat_outip.s_addr = htonl(in.s_addr);
nat->nat_oip = ip->ip_dst;
sum1 = (ntohl(ip->ip_src.s_addr) & 0xffff) +
(ntohl(ip->ip_src.s_addr) >> 16) + ntohs(sport);
sum2 = (in.s_addr & 0xffff) + (in.s_addr >> 16) + ntohs(port);
if (flags & IPN_TCPUDP) {
nat->nat_inport = sport;
nat->nat_outport = port;
nat->nat_oport = dport;
}
} else {
/*
* Otherwise, it's an inbound packet. Most likely, we don't
* want to rewrite source ports and source addresses. Instead,
* we want to rewrite to a fixed internal address and fixed
* internal port.
*/
in.s_addr = ntohl(np->in_inip);
if (!(nport = np->in_pnext))
nport = dport;
nat->nat_inip.s_addr = htonl(in.s_addr);
nat->nat_outip = ip->ip_dst;
nat->nat_oip = ip->ip_src;
sum1 = (ntohl(ip->ip_dst.s_addr) & 0xffff) +
(ntohl(ip->ip_dst.s_addr) >> 16) + ntohs(dport);
sum2 = (in.s_addr & 0xffff) + (in.s_addr >> 16) + ntohs(nport);
if (flags & IPN_TCPUDP) {
nat->nat_inport = nport;
nat->nat_outport = dport;
nat->nat_oport = sport;
}
}
/* Do it twice */
sum1 = (sum1 & 0xffff) + (sum1 >> 16);
sum1 = (sum1 & 0xffff) + (sum1 >> 16);
/* Do it twice */
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
if (sum1 > sum2)
sum2--; /* Because ~1 == -2, We really need ~1 == -1 */
sumd = sum2 - sum1;
sumd = (sumd & 0xffff) + (sumd >> 16);
nat->nat_sumd = (sumd & 0xffff) + (sumd >> 16);
if ((flags & IPN_TCPUDP) && ((sport != port) || (dport != nport))) {
if (direction == NAT_OUTBOUND)
sum1 = (ntohl(ip->ip_src.s_addr) & 0xffff) +
(ntohl(ip->ip_src.s_addr) >> 16);
else
sum1 = (ntohl(ip->ip_dst.s_addr) & 0xffff) +
(ntohl(ip->ip_dst.s_addr) >> 16);
sum2 = (in.s_addr & 0xffff) + (in.s_addr >> 16);
/* Do it twice */
sum1 = (sum1 & 0xffff) + (sum1 >> 16);
sum1 = (sum1 & 0xffff) + (sum1 >> 16);
/* Do it twice */
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
sum2 = (sum2 & 0xffff) + (sum2 >> 16);
if (sum1 > sum2)
sum2--; /* Because ~1 == -2, We really need ~1 == -1 */
sumd = sum2 - sum1;
sumd = (sumd & 0xffff) + (sumd >> 16);
nat->nat_ipsumd = (sumd & 0xffff) + (sumd >> 16);
} else
nat->nat_ipsumd = nat->nat_sumd;
in.s_addr = htonl(in.s_addr);
nat->nat_next = nat_instances;
nat_instances = nat;
natp = &nat_table[0][nat->nat_inip.s_addr % NAT_SIZE];
nat->nat_hstart[0] = natp;
nat->nat_hnext[0] = *natp;
*natp = nat;
natp = &nat_table[1][nat->nat_outip.s_addr % NAT_SIZE];
nat->nat_hstart[1] = natp;
nat->nat_hnext[1] = *natp;
*natp = nat;
nat->nat_ptr = np;
nat->nat_bytes = 0;
nat->nat_pkts = 0;
nat->nat_ifp = fin->fin_ifp;
nat->nat_dir = direction;
if (direction == NAT_OUTBOUND) {
if (flags & IPN_TCPUDP)
tcp->th_sport = htons(port);
} else {
if (flags & IPN_TCPUDP)
tcp->th_dport = htons(nport);
}
nat_stats.ns_added++;
nat_stats.ns_inuse++;
np->in_use++;
return nat;
}
/*
* NB: these lookups don't lock access to the list, it assume it has already
* been done!
*/
/*
* Lookup a nat entry based on the mapped destination ip address/port and
* real source address/port. We use this lookup when receiving a packet,
* we're looking for a table entry, based on the destination address.
* NOTE: THE PACKET BEING CHECKED (IF FOUND) HAS A MAPPING ALREADY.
*/
nat_t *nat_inlookup(ifp, flags, src, sport, mapdst, mapdport)
void *ifp;
register int flags;
struct in_addr src , mapdst;
u_short sport, mapdport;
{
register nat_t *nat;
flags &= IPN_TCPUDP;
nat = nat_table[1][mapdst.s_addr % NAT_SIZE];
for (; nat; nat = nat->nat_hnext[1])
if ((!ifp || ifp == nat->nat_ifp) &&
nat->nat_oip.s_addr == src.s_addr &&
nat->nat_outip.s_addr == mapdst.s_addr &&
flags == nat->nat_flags && (!flags ||
(nat->nat_oport == sport &&
nat->nat_outport == mapdport)))
return nat;
return NULL;
}
/*
* Lookup a nat entry based on the source 'real' ip address/port and
* destination address/port. We use this lookup when sending a packet out,
* we're looking for a table entry, based on the source address.
* NOTE: THE PACKET BEING CHECKED (IF FOUND) HAS A MAPPING ALREADY.
*/
nat_t *nat_outlookup(ifp, flags, src, sport, dst, dport)
void *ifp;
register int flags;
struct in_addr src , dst;
u_short sport, dport;
{
register nat_t *nat;
flags &= IPN_TCPUDP;
nat = nat_table[0][src.s_addr % NAT_SIZE];
for (; nat; nat = nat->nat_hnext[0])
if ((!ifp || ifp == nat->nat_ifp) &&
nat->nat_inip.s_addr == src.s_addr &&
nat->nat_oip.s_addr == dst.s_addr &&
flags == nat->nat_flags && (!flags ||
(nat->nat_inport == sport && nat->nat_oport == dport)))
return nat;
return NULL;
}
/*
* Lookup a nat entry based on the mapped source ip address/port and
* real destination address/port. We use this lookup when sending a packet
* out, we're looking for a table entry, based on the source address.
*/
nat_t *nat_lookupmapip(ifp, flags, mapsrc, mapsport, dst, dport)
void *ifp;
register int flags;
struct in_addr mapsrc , dst;
u_short mapsport, dport;
{
register nat_t *nat;
flags &= IPN_TCPUDP;
nat = nat_table[1][mapsrc.s_addr % NAT_SIZE];
for (; nat; nat = nat->nat_hnext[0])
if ((!ifp || ifp == nat->nat_ifp) &&
nat->nat_oip.s_addr == dst.s_addr &&
nat->nat_outip.s_addr == mapsrc.s_addr &&
flags == nat->nat_flags && (!flags ||
(nat->nat_outport == mapsport &&
nat->nat_oport == dport)))
return nat;
return NULL;
}
/*
* Lookup the NAT tables to search for a matching redirect
*/
nat_t *nat_lookupredir(np)
register natlookup_t *np;
{
nat_t *nat;
/*
* If nl_inip is non null, this is a lookup based on the real
* ip address. Else, we use the fake.
*/
if ((nat = nat_outlookup(NULL, IPN_TCPUDP, np->nl_inip, np->nl_inport,
np->nl_outip, np->nl_outport))) {
np->nl_inip = nat->nat_outip;
np->nl_inport = nat->nat_outport;
}
return nat;
}
/*
* Packets going out on the external interface go through this.
* Here, the source address requires alteration, if anything.
*/
int ip_natout(ip, hlen, fin)
ip_t *ip;
int hlen;
fr_info_t *fin;
{
register ipnat_t *np;
register u_long ipa;
tcphdr_t *tcp = NULL;
nat_t *nat;
u_short nflags = 0, sport = 0, dport = 0, *csump = NULL;
struct ifnet *ifp;
frentry_t *fr;
if ((fr = fin->fin_fr) && !(fr->fr_flags & FR_DUP) &&
fr->fr_tif.fd_ifp && fr->fr_tif.fd_ifp != (void *)-1)
ifp = fr->fr_tif.fd_ifp;
else
ifp = fin->fin_ifp;
if (!(ip->ip_off & 0x1fff) && !(fin->fin_fi.fi_fl & FI_SHORT)) {
if (ip->ip_p == IPPROTO_TCP)
nflags = IPN_TCP;
else if (ip->ip_p == IPPROTO_UDP)
nflags = IPN_UDP;
if (nflags) {
tcp = (tcphdr_t *)fin->fin_dp;
sport = tcp->th_sport;
dport = tcp->th_dport;
}
}
ipa = ip->ip_src.s_addr;
MUTEX_ENTER(&ipf_nat);
if ((nat = ipfr_nat_knownfrag(ip, fin)))
;
else if ((nat = nat_outlookup(fin->fin_ifp, nflags, ip->ip_src, sport,
ip->ip_dst, dport)))
np = nat->nat_ptr;
else
/*
* If there is no current entry in the nat table for this IP#,
* create one for it (if there is a matching rule).
*/
for (np = nat_list; np; np = np->in_next)
if ((np->in_ifp == ifp) && np->in_space &&
(!np->in_flags || (np->in_flags & nflags)) &&
((ipa & np->in_inmsk) == np->in_inip) &&
((np->in_redir & NAT_MAP) ||
(np->in_pnext == sport))) {
if (*np->in_plabel && !ap_ok(ip, tcp, np))
continue;
/*
* If it's a redirection, then we don't want to
* create new outgoing port stuff.
* Redirections are only for incoming
* connections.
*/
if (!(np->in_redir & NAT_MAP))
continue;
if ((nat = nat_new(np, ip, fin, nflags,
NAT_OUTBOUND)))
#ifdef IPFILTER_LOG
nat_log(nat, (u_short)np->in_redir);
#else
;
#endif
break;
}
if (nat) {
if (!nat->nat_frag && fin->fin_fi.fi_fl & FI_FRAG)
ipfr_nat_newfrag(ip, fin, 0, nat);
nat->nat_age = fr_defnatage;
ip->ip_src = nat->nat_outip;
nat->nat_bytes += ip->ip_len;
nat->nat_pkts++;
/*
* Fix up checksums, not by recalculating them, but
* simply computing adjustments.
*/
#if SOLARIS
if (nat->nat_dir == NAT_OUTBOUND)
fix_outcksum(&ip->ip_sum, nat->nat_ipsumd);
else
fix_incksum(&ip->ip_sum, nat->nat_ipsumd);
#endif
if (nflags && !(ip->ip_off & 0x1fff) &&
!(fin->fin_fi.fi_fl & FI_SHORT)) {
if (nat->nat_outport)
tcp->th_sport = nat->nat_outport;
if (ip->ip_p == IPPROTO_TCP) {
csump = &tcp->th_sum;
fr_tcp_age(&nat->nat_age,
nat->nat_state, ip, fin,1);
/*
* Increase this because we may have
* "keep state" following this too and
* packet storms can occur if this is
* removed too quickly.
*/
if (nat->nat_age == fr_tcpclosed)
nat->nat_age = fr_tcplastack;
} else if (ip->ip_p == IPPROTO_UDP) {
udphdr_t *udp = (udphdr_t *)tcp;
if (udp->uh_sum)
csump = &udp->uh_sum;
} else if (ip->ip_p == IPPROTO_ICMP) {
icmphdr_t *ic = (icmphdr_t *)tcp;
csump = &ic->icmp_cksum;
}
if (csump) {
if (nat->nat_dir == NAT_OUTBOUND)
fix_outcksum(csump,
nat->nat_sumd);
else
fix_incksum(csump,
nat->nat_sumd);
}
}
(void) ap_check(ip, tcp, fin, nat);
nat_stats.ns_mapped[1]++;
MUTEX_EXIT(&ipf_nat);
return 1;
}
MUTEX_EXIT(&ipf_nat);
return 0;
}
/*
* Packets coming in from the external interface go through this.
* Here, the destination address requires alteration, if anything.
*/
int ip_natin(ip, hlen, fin)
ip_t *ip;
int hlen;
fr_info_t *fin;
{
register ipnat_t *np;
register struct in_addr in;
struct ifnet *ifp = fin->fin_ifp;
tcphdr_t *tcp = NULL;
u_short sport = 0, dport = 0, nflags = 0, *csump = NULL;
nat_t *nat;
if (!(ip->ip_off & 0x1fff) && !(fin->fin_fi.fi_fl & FI_SHORT)) {
if (ip->ip_p == IPPROTO_TCP)
nflags = IPN_TCP;
else if (ip->ip_p == IPPROTO_UDP)
nflags = IPN_UDP;
if (nflags) {
tcp = (tcphdr_t *)((char *)ip + hlen);
dport = tcp->th_dport;
sport = tcp->th_sport;
}
}
in = ip->ip_dst;
MUTEX_ENTER(&ipf_nat);
if ((nat = ipfr_nat_knownfrag(ip, fin)))
;
else if ((nat = nat_inlookup(fin->fin_ifp, nflags, ip->ip_src, sport,
ip->ip_dst, dport)))
np = nat->nat_ptr;
else
/*
* If there is no current entry in the nat table for this IP#,
* create one for it (if there is a matching rule).
*/
for (np = nat_list; np; np = np->in_next)
if ((np->in_ifp == ifp) &&
(!np->in_flags || (nflags & np->in_flags)) &&
((in.s_addr & np->in_outmsk) == np->in_outip) &&
(np->in_redir & NAT_REDIRECT ||
np->in_pmin == dport)) {
/*
* If this rule (np) is a redirection, rather
* than a mapping, then do a nat_new.
* Otherwise, if it's just a mapping, do a
* continue;
*/
if (!(np->in_redir & NAT_REDIRECT))
continue;
if ((nat = nat_new(np, ip, fin, nflags,
NAT_INBOUND)))
#ifdef IPFILTER_LOG
nat_log(nat, (u_short)np->in_redir);
#else
;
#endif
break;
}
if (nat) {
if (!nat->nat_frag && fin->fin_fi.fi_fl & FI_FRAG)
ipfr_nat_newfrag(ip, fin, 0, nat);
(void) ap_check(ip, tcp, fin, nat);
nat->nat_age = fr_defnatage;
ip->ip_dst = nat->nat_inip;
nat->nat_bytes += ip->ip_len;
nat->nat_pkts++;
/*
* Fix up checksums, not by recalculating them, but
* simply computing adjustments.
*/
#if SOLARIS
if (nat->nat_dir == NAT_OUTBOUND)
fix_incksum(&ip->ip_sum, nat->nat_ipsumd);
else
fix_outcksum(&ip->ip_sum, nat->nat_ipsumd);
#endif
if (nflags && !(ip->ip_off & 0x1fff) &&
!(fin->fin_fi.fi_fl & FI_SHORT)) {
if (nat->nat_inport)
tcp->th_dport = nat->nat_inport;
if (ip->ip_p == IPPROTO_TCP) {
csump = &tcp->th_sum;
fr_tcp_age(&nat->nat_age,
nat->nat_state, ip, fin,0);
/*
* Increase this because we may have
* "keep state" following this too and
* packet storms can occur if this is
* removed too quickly.
*/
if (nat->nat_age == fr_tcpclosed)
nat->nat_age = fr_tcplastack;
} else if (ip->ip_p == IPPROTO_UDP) {
udphdr_t *udp = (udphdr_t *)tcp;
if (udp->uh_sum)
csump = &udp->uh_sum;
} else if (ip->ip_p == IPPROTO_ICMP) {
icmphdr_t *ic = (icmphdr_t *)tcp;
csump = &ic->icmp_cksum;
}
if (csump) {
if (nat->nat_dir == NAT_OUTBOUND)
fix_incksum(csump,
nat->nat_sumd);
else
fix_outcksum(csump,
nat->nat_sumd);
}
}
nat_stats.ns_mapped[0]++;
MUTEX_EXIT(&ipf_nat);
return 1;
}
MUTEX_EXIT(&ipf_nat);
return 0;
}
/*
* Free all memory used by NAT structures allocated at runtime.
*/
void ip_natunload()
{
int s;
MUTEX_ENTER(&ipf_nat);
SPLNET(s);
(void) clear_natlist();
(void) flush_nattable();
(void) ap_unload();
SPLX(s)
MUTEX_EXIT(&ipf_nat);
}
/*
* Slowly expire held state for NAT entries. Timeouts are set in
* expectation of this being called twice per second.
*/
void ip_natexpire()
{
register struct nat *nat, **natp;
int s;
MUTEX_ENTER(&ipf_nat);
SPLNET(s);
for (natp = &nat_instances; (nat = *natp); ) {
if (--nat->nat_age) {
natp = &nat->nat_next;
continue;
}
*natp = nat->nat_next;
#ifdef IPFILTER_LOG
nat_log(nat, NL_EXPIRE);
#endif
nat_delete(nat);
nat_stats.ns_expire++;
}
SPLX(s);
MUTEX_EXIT(&ipf_nat);
}
#ifdef IPFILTER_LOG
void nat_log(nat, type)
struct nat *nat;
u_short type;
{
struct ipnat *np;
struct natlog natl;
int rulen;
if (iplused[IPL_LOGNAT] + sizeof(natl) > IPLLOGSIZE) {
nat_stats.ns_logfail++;
return;
}
if (iplh[IPL_LOGNAT] == iplbuf[IPL_LOGNAT] + IPLLOGSIZE)
iplh[IPL_LOGNAT] = iplbuf[IPL_LOGNAT];
# ifdef sun
uniqtime(&natl);
# endif
# if BSD >= 199306 || defined(__FreeBSD__)
microtime((struct timeval *)&natl);
# endif
natl.nl_inip = nat->nat_inip;
natl.nl_outip = nat->nat_outip;
natl.nl_origip = nat->nat_oip;
natl.nl_bytes = nat->nat_bytes;
natl.nl_pkts = nat->nat_pkts;
natl.nl_origport = nat->nat_oport;
natl.nl_inport = nat->nat_inport;
natl.nl_outport = nat->nat_outport;
natl.nl_type = type;
natl.nl_rule = -1;
if (nat->nat_ptr) {
for (rulen = 0, np = nat_list; np; np = np->in_next, rulen++)
if (np == nat->nat_ptr) {
natl.nl_rule = rulen;
break;
}
}
if (!fr_copytolog(IPL_LOGNAT, (char *)&natl, sizeof(natl))) {
iplused[IPL_LOGNAT] += sizeof(natl);
nat_stats.ns_logged++;
} else
nat_stats.ns_logfail++;
wakeup(iplbuf[IPL_LOGNAT]);
}
#endif
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