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NetBSD/sys/netinet/ip_nat.c

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/* $NetBSD: ip_nat.c,v 1.21 1998/11/14 07:42:37 tls Exp $ */
/*
* Copyright (C) 1995-1997 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)
static const char sccsid[] = "@(#)ip_nat.c 1.11 6/5/96 (C) 1995 Darren Reed";
static const char rcsid[] = "@(#)Id: ip_nat.c,v 2.0.2.44.2.13 1998/06/13 13:42:47 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/fcntl.h>
#else
# include <sys/ioctl.h>
#endif
#include <sys/fcntl.h>
#include <sys/uio.h>
#ifndef linux
# include <sys/protosw.h>
#endif
#include <sys/socket.h>
#if defined(_KERNEL) && !defined(linux)
# include <sys/systm.h>
#endif
#if !defined(__SVR4) && !defined(__svr4__)
# ifndef linux
# include <sys/mbuf.h>
# endif
#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 __sgi
# ifdef IFF_DRVRLOCK /* IRIX6 */
#include <sys/hashing.h>
#include <netinet/in_var.h>
# endif
#endif
#ifdef RFC1825
#include <vpn/md5.h>
#include <vpn/ipsec.h>
extern struct ifnet vpnif;
#endif
#ifndef linux
# include <netinet/ip_var.h>
#endif
#include <netinet/tcp.h>
#include <netinet/udp.h>
#include <netinet/ip_icmp.h>
#include "netinet/ip_compat.h"
#include <netinet/tcpip.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, /* 10 minutes (600 seconds) */
fr_defnaticmpage = 6; /* 3 seconds */
natstat_t nat_stats;
#if (SOLARIS || defined(__sgi)) && defined(_KERNEL)
extern kmutex_t ipf_rw;
extern krwlock_t ipf_nat;
#endif
static int nat_flushtable __P((void));
static int nat_clearlist __P((void));
static void nat_delete __P((struct nat *));
static int nat_ifpaddr __P((nat_t *, void *, struct in_addr *));
#define LONG_SUM(in) (((in) & 0xffff) + ((in) >> 16))
#define CALC_SUMD(s1, s2, sd) { \
/* Do it twice */ \
(s1) = ((s1) & 0xffff) + ((s1) >> 16); \
(s1) = ((s1) & 0xffff) + ((s1) >> 16); \
/* Do it twice */ \
(s2) = ((s2) & 0xffff) + ((s2) >> 16); \
(s2) = ((s2) & 0xffff) + ((s2) >> 16); \
/* Because ~1 == -2, We really need ~1 == -1 */ \
if ((s1) > (s2)) (s2)--; \
(sd) = (s2) - (s1); \
(sd) = ((sd) & 0xffff) + ((sd) >> 16); }
void fix_outcksum(sp, n)
u_short *sp;
u_32_t n;
{
register u_short sumshort;
register u_32_t sum1;
if (!n)
return;
sum1 = (~ntohs(*sp)) & 0xffff;
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_32_t n;
{
register u_short sumshort;
register u_32_t sum1;
if (!n)
return;
#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)
#if defined(__NetBSD__) || defined(__OpenBSD__)
u_long cmd;
#else
int cmd;
#endif
caddr_t data;
int mode;
{
register ipnat_t *nat, *nt, *n = NULL, **np = NULL;
ipnat_t natd;
int error = 0, ret;
#if defined(_KERNEL) && !SOLARIS
int s;
#endif
nat = NULL; /* XXX gcc -Wuninitialized */
KMALLOC(nt, ipnat_t *, sizeof(*nt));
if ((cmd == SIOCADNAT) || (cmd == SIOCRMNAT))
IRCOPY(data, (char *)&natd, sizeof(natd));
/*
* For add/delete, look to see if the NAT entry is already present
*/
SPL_NET(s);
WRITE_ENTER(&ipf_nat);
if ((cmd == SIOCADNAT) || (cmd == SIOCRMNAT)) {
nat = &natd;
nat->in_inip &= nat->in_inmsk;
nat->in_outip &= nat->in_outmsk;
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 defined(__NetBSD__)
if ((securelevel >= 2) || !(mode & FWRITE)) {
#else
if (!(mode & FWRITE)) {
#endif
error = EPERM;
break;
}
if (n) {
error = EEXIST;
break;
}
n = nt;
nt = NULL;
if (n == NULL) {
error = ENOMEM;
break;
}
bcopy((char *)nat, (char *)n, sizeof(*n));
n->in_ifp = (void *)GETUNIT(n->in_ifname);
if (!n->in_ifp)
n->in_ifp = (void *)-1;
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_outmsk)
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;
n = NULL;
ATOMIC_INC(nat_stats.ns_rules);
break;
case SIOCRMNAT :
#if defined(__NetBSD__)
if ((securelevel >= 2) || !(mode & FWRITE)) {
#else
if (!(mode & FWRITE)) {
#endif
error = EPERM;
n = NULL;
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);
ATOMIC_DEC(nat_stats.ns_rules);
} else {
n->in_flags |= IPN_DELETE;
n->in_next = NULL;
}
n = NULL;
break;
case SIOCGNATS :
MUTEX_DOWNGRADE(&ipf_nat);
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;
MUTEX_DOWNGRADE(&ipf_nat);
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 defined(__NetBSD__)
if ((securelevel >= 2) || !(mode & FWRITE)) {
#else
if (!(mode & FWRITE)) {
#endif
error = EPERM;
break;
}
ret = nat_flushtable();
(void) ap_unload();
MUTEX_DOWNGRADE(&ipf_nat);
IWCOPY((caddr_t)&ret, data, sizeof(ret));
break;
case SIOCCNATL :
#if defined(__NetBSD__)
if ((securelevel >= 2) || !(mode & FWRITE)) {
#else
if (!(mode & FWRITE)) {
#endif
error = EPERM;
break;
}
ret = nat_clearlist();
MUTEX_DOWNGRADE(&ipf_nat);
IWCOPY((caddr_t)&ret, data, sizeof(ret));
break;
case FIONREAD :
#ifdef IPFILTER_LOG
MUTEX_DOWNGRADE(&ipf_nat);
IWCOPY((caddr_t)&iplused[IPL_LOGNAT], (caddr_t)data,
sizeof(iplused[IPL_LOGNAT]));
#endif
break;
}
RWLOCK_EXIT(&ipf_nat);
SPL_X(s);
if (nt)
KFREE(nt);
return error;
}
/*
* Delete a nat entry from the various lists and table.
*/
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 there is an active reference from the nat entry to its parent
* rule, decrement the rule's reference count and free it too if no
* longer being used.
*/
if ((ipn = natd->nat_ptr)) {
ATOMIC_INC(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--;
}
}
/*
* If there's a fragment table entry too for this nat entry, then
* dereference that as well.
*/
ipfr_forget((void *)natd);
KFREE(natd);
}
/*
* nat_flushtable - clear the NAT table of all mapping entries.
*/
static int nat_flushtable()
{
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;
}
/*
* nat_clearlist - delete all entries in the active NAT mapping list.
*/
static int nat_clearlist()
{
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);
ATOMIC_DEC(nat_stats.ns_rules);
i++;
} else {
n->in_flags |= IPN_DELETE;
n->in_next = NULL;
}
}
nat_stats.ns_inuse = 0;
return i;
}
/*
* return the first IP Address associated with an interface
*/
static int nat_ifpaddr(nat, ifptr, inp)
nat_t *nat;
void *ifptr;
struct in_addr *inp;
{
#if SOLARIS
ill_t *ill = ifptr;
#else
struct ifnet *ifp = ifptr;
#endif
struct in_addr in;
#if SOLARIS
in.s_addr = ntohl(ill->ill_ipif->ipif_local_addr);
#else /* SOLARIS */
# if linux
;
# else /* linux */
struct ifaddr *ifa;
struct sockaddr_in *sin;
# if (__FreeBSD_version >= 300000)
ifa = TAILQ_FIRST(&ifp->if_addrhead);
# else
# if defined(__NetBSD__) || defined(__OpenBSD__)
ifa = ifp->if_addrlist.tqh_first;
# else
# if defined(__sgi) && defined(IFF_DRVRLOCK) /* IRIX 6 */
ifa = &((struct in_ifaddr *)ifp->in_ifaddr)->ia_ifa;
# else
ifa = ifp->if_addrlist;
# endif
# endif /* __NetBSD__ || __OpenBSD__ */
# endif /* __FreeBSD_version >= 300000 */
# if (BSD < 199306) && !(/*IRIX6*/defined(__sgi) && defined(IFF_DRVRLOCK))
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
# if defined(__NetBSD__) || defined(__OpenBSD__)
ifa = ifa->ifa_list.tqe_next;
# else
ifa = ifa->ifa_next;
# endif
# endif /* __FreeBSD_version >= 300000 */
if (ifa)
sin = (SOCKADDR_IN *)ifa->ifa_addr;
}
if (!ifa)
sin = NULL;
if (!sin) {
KFREE(nat);
return -1;
}
# endif /* (BSD < 199306) && (!__sgi && IFF_DRVLOCK) */
in = sin->sin_addr;
in.s_addr = ntohl(in.s_addr);
# endif /* linux */
#endif /* SOLARIS */
*inp = in;
return 0;
}
/*
* 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_32_t sum1, sum2, sumd, l;
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 it's an outbound packet which doesn't match any existing
* record, then create a new port
*/
l = 0;
do {
l++;
port = 0;
in.s_addr = np->in_nip;
if (!in.s_addr && (np->in_outmsk == 0xffffffff)) {
if ((l > 1) ||
nat_ifpaddr(nat, fin->fin_ifp, &in) == -1) {
KFREE(nat);
return NULL;
}
} else if (!in.s_addr && !np->in_outmsk) {
if (l > 1) {
KFREE(nat);
return NULL;
}
in.s_addr = ntohl(ip->ip_src.s_addr);
if (nflags & IPN_TCPUDP)
port = sport;
} else 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 = port;
} else {
if (flags & IPN_TCPUDP)
tcp->th_dport = nport;
}
ATOMIC_INC(nat_stats.ns_added);
ATOMIC_INC(nat_stats.ns_inuse);
ATOMIC_INC(np->in_use);
return nat;
}
nat_t *nat_icmpinlookup(ip, fin)
ip_t *ip;
fr_info_t *fin;
{
icmphdr_t *icmp;
tcphdr_t *tcp = NULL;
ip_t *oip;
int flags = 0, type;
icmp = (icmphdr_t *)fin->fin_dp;
/*
* Does it at least have the return (basic) IP header ?
* Only a basic IP header (no options) should be with an ICMP error
* header.
*/
if ((ip->ip_hl != 5) || (ip->ip_len < sizeof(*icmp) + sizeof(ip_t)))
return NULL;
type = icmp->icmp_type;
/*
* If it's not an error type, then return.
*/
if ((type != ICMP_UNREACH) && (type != ICMP_SOURCEQUENCH) &&
(type != ICMP_REDIRECT) && (type != ICMP_TIMXCEED) &&
(type != ICMP_PARAMPROB))
return NULL;
oip = (ip_t *)((char *)fin->fin_dp + 8);
if (oip->ip_p == IPPROTO_TCP)
flags = IPN_TCP;
else if (oip->ip_p == IPPROTO_UDP)
flags = IPN_UDP;
if (flags & IPN_TCPUDP) {
tcp = (tcphdr_t *)((char *)oip + (oip->ip_hl << 2));
return nat_inlookup(fin->fin_ifp, flags, oip->ip_dst,
tcp->th_dport, oip->ip_src, tcp->th_sport);
}
return nat_inlookup(fin->fin_ifp, 0, oip->ip_src, 0, oip->ip_dst, 0);
}
/*
* This should *ONLY* be used for incoming packets to make sure a NAT'd ICMP
* packet gets correctly recognised.
*/
nat_t *nat_icmpin(ip, fin, nflags)
ip_t *ip;
fr_info_t *fin;
int *nflags;
{
icmphdr_t *icmp;
nat_t *nat;
ip_t *oip;
int flags = 0;
if (!(nat = nat_icmpinlookup(ip, fin)))
return NULL;
*nflags = IPN_ICMPERR;
icmp = (icmphdr_t *)fin->fin_dp;
oip = (ip_t *)((char *)icmp + 8);
if (oip->ip_p == IPPROTO_TCP)
flags = IPN_TCP;
else if (oip->ip_p == IPPROTO_UDP)
flags = IPN_UDP;
/*
* Need to adjust ICMP header to include the real IP#'s and
* port #'s. Only apply a checksum change relative to the
* IP address change is it will be modified again in ip_natout
* for both address and port. Two checksum changes are
* necessary for the two header address changes. Be careful
* to only modify the checksum once for the port # and twice
* for the IP#.
*/
if (flags & IPN_TCPUDP) {
tcphdr_t *tcp = (tcphdr_t *)(oip + 1);
u_32_t sum1, sum2, sumd;
struct in_addr in;
if (nat->nat_dir == NAT_OUTBOUND) {
sum1 = LONG_SUM(ntohl(oip->ip_src.s_addr));
in = nat->nat_outip;
oip->ip_src = in;
tcp->th_sport = nat->nat_outport;
} else {
sum1 = LONG_SUM(ntohl(oip->ip_dst.s_addr));
in = nat->nat_inip;
oip->ip_dst = in;
tcp->th_dport = nat->nat_inport;
}
sum2 = LONG_SUM(in.s_addr);
CALC_SUMD(sum1, sum2, sumd);
sumd = (sumd & 0xffff) + (sumd >> 16);
if (nat->nat_dir == NAT_OUTBOUND) {
fix_incksum(&oip->ip_sum, sumd);
fix_incksum(&icmp->icmp_cksum, sumd);
} else {
fix_outcksum(&oip->ip_sum, sumd);
fix_outcksum(&icmp->icmp_cksum, sumd);
}
/*
* TCP checksum doesn't make it into the 1st eight
* bytes but UDP does.
*/
if (ip->ip_p == IPPROTO_UDP) {
udphdr_t *udp = (udphdr_t *)tcp;
if (udp->uh_sum) {
if (nat->nat_dir == NAT_OUTBOUND)
fix_incksum(&udp->uh_sum,
nat->nat_sumd);
else
fix_outcksum(&udp->uh_sum,
nat->nat_sumd);
}
}
} else
ip->ip_dst = nat->nat_outip;
nat->nat_age = fr_defnaticmpage;
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.
*/
#ifdef __STDC__
nat_t *nat_inlookup(void *ifp, int flags, struct in_addr src, u_short sport, struct in_addr mapdst, u_short mapdport)
#else
nat_t *nat_inlookup(ifp, flags, src, sport, mapdst, mapdport)
void *ifp;
register int flags;
struct in_addr src , mapdst;
u_short sport, mapdport;
#endif
{
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.
*/
#ifdef __STDC__
nat_t *nat_outlookup(void *ifp, int flags, struct in_addr src, u_short sport, struct in_addr dst, u_short dport)
#else
nat_t *nat_outlookup(ifp, flags, src, sport, dst, dport)
void *ifp;
register int flags;
struct in_addr src , dst;
u_short sport, dport;
#endif
{
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.
*/
#ifdef __STDC__
nat_t *nat_lookupmapip(void *ifp, int flags, struct in_addr mapsrc, u_short mapsport, struct in_addr dst, u_short dport)
#else
nat_t *nat_lookupmapip(ifp, flags, mapsrc, mapsport, dst, dport)
void *ifp;
register int flags;
struct in_addr mapsrc , dst;
u_short mapsport, dport;
#endif
{
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, np->nl_flags, np->nl_inip,
np->nl_inport, np->nl_outip,
np->nl_outport))) {
np->nl_realip = nat->nat_outip;
np->nl_realport = 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_32_t ipa;
tcphdr_t *tcp = NULL;
u_short nflags = 0, sport = 0, dport = 0, *csump = NULL;
struct ifnet *ifp;
frentry_t *fr;
nat_t *nat;
int natadd = 1;
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;
READ_ENTER(&ipf_nat);
if ((ip->ip_off & (IP_OFFMASK|IP_MF)) &&
(nat = ipfr_nat_knownfrag(ip, fin)))
natadd = 0;
else if ((nat = nat_outlookup(ifp, nflags, ip->ip_src, sport,
ip->ip_dst, dport)))
;
else {
RWLOCK_EXIT(&ipf_nat);
WRITE_ENTER(&ipf_nat);
/*
* 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;
}
MUTEX_DOWNGRADE(&ipf_nat);
}
if (nat) {
if (natadd && fin->fin_fi.fi_fl & FI_FRAG)
ipfr_nat_newfrag(ip, fin, 0, nat);
ip->ip_src = nat->nat_outip;
MUTEX_ENTER(&ipf_rw);
nat->nat_age = fr_defnatage;
nat->nat_bytes += ip->ip_len;
nat->nat_pkts++;
MUTEX_EXIT(&ipf_rw);
/*
* Fix up checksums, not by recalculating them, but
* simply computing adjustments.
*/
#if SOLARIS || defined(__sgi)
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;
MUTEX_ENTER(&ipf_rw);
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;
MUTEX_EXIT(&ipf_rw);
} 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);
ATOMIC_INC(nat_stats.ns_mapped[1]);
RWLOCK_EXIT(&ipf_nat);
return -2;
}
RWLOCK_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, *csump = NULL;
nat_t *nat;
int nflags = 0, natadd = 1;
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;
READ_ENTER(&ipf_nat);
if ((ip->ip_p == IPPROTO_ICMP) && (nat = nat_icmpin(ip, fin, &nflags)))
;
else if ((ip->ip_off & IP_OFFMASK) &&
(nat = ipfr_nat_knownfrag(ip, fin)))
natadd = 0;
else if ((nat = nat_inlookup(fin->fin_ifp, nflags, ip->ip_src, sport,
ip->ip_dst, dport)))
;
else {
RWLOCK_EXIT(&ipf_nat);
WRITE_ENTER(&ipf_nat);
/*
* 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 || np->in_pmin == dport)) {
if ((nat = nat_new(np, ip, fin, nflags,
NAT_INBOUND)))
#ifdef IPFILTER_LOG
nat_log(nat, (u_short)np->in_redir);
#else
;
#endif
break;
}
MUTEX_DOWNGRADE(&ipf_nat);
}
if (nat) {
if (natadd && fin->fin_fi.fi_fl & FI_FRAG)
ipfr_nat_newfrag(ip, fin, 0, nat);
MUTEX_ENTER(&ipf_rw);
(void) ap_check(ip, tcp, fin, nat);
if (nflags != IPN_ICMPERR)
nat->nat_age = fr_defnatage;
nat->nat_bytes += ip->ip_len;
nat->nat_pkts++;
MUTEX_EXIT(&ipf_rw);
ip->ip_dst = nat->nat_inip;
/*
* Fix up checksums, not by recalculating them, but
* simply computing adjustments.
*/
#if SOLARIS || defined(__sgi)
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 & IPN_TCPUDP) && !(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;
MUTEX_ENTER(&ipf_rw);
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;
MUTEX_EXIT(&ipf_rw);
} 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);
}
}
ATOMIC_INC(nat_stats.ns_mapped[0]);
RWLOCK_EXIT(&ipf_nat);
return -2;
}
RWLOCK_EXIT(&ipf_nat);
return 0;
}
/*
* Free all memory used by NAT structures allocated at runtime.
*/
void ip_natunload()
{
WRITE_ENTER(&ipf_nat);
(void) nat_clearlist();
(void) nat_flushtable();
(void) ap_unload();
RWLOCK_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;
#if defined(_KERNEL) && !SOLARIS
int s;
#endif
SPL_NET(s);
WRITE_ENTER(&ipf_nat);
for (natp = &nat_instances; (nat = *natp); ) {
ATOMIC_DEC(nat->nat_age);
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);
ATOMIC_INC(nat_stats.ns_expire);
}
ap_expire();
RWLOCK_EXIT(&ipf_nat);
SPL_X(s);
}
/*
*/
#ifdef __STDC__
void ip_natsync(void *ifp)
#else
void ip_natsync(ifp)
void *ifp;
#endif
{
register nat_t *nat;
register u_32_t sum1, sum2, sumd;
struct in_addr in;
ipnat_t *np;
#if defined(_KERNEL) && !SOLARIS
int s;
#endif
SPL_NET(s);
WRITE_ENTER(&ipf_nat);
for (nat = nat_instances; nat; nat = nat->nat_next)
if ((ifp == nat->nat_ifp) && (np = nat->nat_ptr))
if ((np->in_outmsk == 0xffffffff) && !np->in_nip) {
/*
* Change the map-to address to be the same
* as the new one.
*/
sum1 = nat->nat_outip.s_addr;
if (nat_ifpaddr(nat, ifp, &in) == -1)
nat->nat_outip.s_addr = htonl(in.s_addr);
sum2 = nat->nat_outip.s_addr;
/*
* Readjust the checksum adjustment to take
* into account the new IP#.
*
* 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);
/* Because ~1 == -2, We really need ~1 == -1 */
if (sum1 > sum2)
sum2--;
sumd = sum2 - sum1;
sumd = (sumd & 0xffff) + (sumd >> 16);
sumd += nat->nat_sumd;
nat->nat_sumd = (sumd & 0xffff) + (sumd >> 16);
}
RWLOCK_EXIT(&ipf_nat);
SPL_X(s);
}
#ifdef IPFILTER_LOG
# ifdef __STDC__
void nat_log(struct nat *nat, u_short type)
# else
void nat_log(nat, type)
struct nat *nat;
u_short type;
# endif
{
struct ipnat *np;
struct natlog natl;
void *items[1];
size_t sizes[1];
int rulen, types[1];
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;
}
}
items[0] = &natl;
sizes[0] = sizeof(natl);
types[0] = 0;
(void) ipllog(IPL_LOGNAT, 0, items, sizes, types, 1);
}
#endif
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