/* * Copyright (C) 1995-2001 by Darren Reed. * * See the IPFILTER.LICENCE file for details on licencing. * * Added redirect stuff and a LOT of bug fixes. (mcn@EnGarde.com) * * @(#)ip_nat.c 1.11 6/5/96 (C) 1995 Darren Reed * @(#)$Id: ip_nat.c,v 2.37.2.70 2002/08/28 12:45:48 darrenr Exp $ * $FreeBSD: src/sys/contrib/ipfilter/netinet/ip_nat.c,v 1.22.2.8 2004/07/04 09:24:39 darrenr Exp $ * $DragonFly: src/sys/contrib/ipfilter/netinet/ip_nat.c,v 1.11 2005/06/05 12:17:46 corecode Exp $ */ #if (defined(__DragonFly__) || defined(__FreeBSD__)) && defined(KERNEL) && !defined(_KERNEL) #define _KERNEL #endif #if defined(__sgi) && (IRIX > 602) # include #endif #include #include #include #include #include #if defined(__NetBSD__) && (NetBSD >= 199905) && !defined(IPFILTER_LKM) && \ defined(_KERNEL) # include "opt_ipfilter_log.h" #endif #if !defined(_KERNEL) && !defined(KERNEL) # include # include # include #endif #if (defined(KERNEL) || defined(_KERNEL)) && (defined(__DragonFly__) || __FreeBSD_version >= 220000) # include # include #else # include #endif #include #ifndef linux # include #endif #include #if defined(_KERNEL) && !defined(linux) # include #endif #if !defined(__SVR4) && !defined(__svr4__) # ifndef linux # include # endif #else # include # include # ifdef _KERNEL # include # endif # include # include #endif #if defined(__DragonFly__) || __FreeBSD_version >= 300000 # include #endif #if defined(__DragonFly__) && defined(_KERNEL) # include #endif #include #if defined(__DragonFly__) || __FreeBSD_version >= 300000 # include # if defined(_KERNEL) && !defined(IPFILTER_LKM) # include "opt_ipfilter.h" # endif #endif #ifdef sun # include #endif #include #include #include #include #ifdef __sgi # ifdef IFF_DRVRLOCK /* IRIX6 */ #include #include # endif #endif #ifdef RFC1825 # include # include extern struct ifnet vpnif; #endif #ifndef linux # include # include #endif #include #include #include #include "ip_compat.h" #include #include "ip_fil.h" #include "ip_nat.h" #include "ip_frag.h" #include "ip_state.h" #include "ip_proxy.h" #if defined(__DragonFly__) || __FreeBSD_version >= 300000 # include #endif #ifndef MIN # define MIN(a,b) (((a)<(b))?(a):(b)) #endif #undef SOCKADDR_IN #define SOCKADDR_IN struct sockaddr_in static const char sccsid[] = "@(#)ip_nat.c 1.11 6/5/96 (C) 1995 Darren Reed"; nat_t **nat_table[2] = { NULL, NULL }, *nat_instances = NULL; ipnat_t *nat_list = NULL; u_int ipf_nattable_max = NAT_TABLE_MAX; u_int ipf_nattable_sz = NAT_TABLE_SZ; u_int ipf_natrules_sz = NAT_SIZE; u_int ipf_rdrrules_sz = RDR_SIZE; u_int ipf_hostmap_sz = HOSTMAP_SIZE; u_32_t nat_masks = 0; u_32_t rdr_masks = 0; ipnat_t **nat_rules = NULL; ipnat_t **rdr_rules = NULL; hostmap_t **maptable = NULL; u_long fr_defnatage = DEF_NAT_AGE, fr_defnaticmpage = 6; /* 3 seconds */ natstat_t nat_stats; int fr_nat_lock = 0; #if (SOLARIS || defined(__sgi)) && defined(_KERNEL) extern kmutex_t ipf_rw; extern KRWLOCK_T ipf_nat; #endif static int nat_flushtable (void); static void nat_addnat (struct ipnat *); static void nat_addrdr (struct ipnat *); static void nat_delete (struct nat *); static void nat_delrdr (struct ipnat *); static void nat_delnat (struct ipnat *); static int fr_natgetent (caddr_t); static int fr_natgetsz (caddr_t); static int fr_natputent (caddr_t); static void nat_tabmove (fr_info_t *, nat_t *); static int nat_match (fr_info_t *, ipnat_t *, ip_t *); static hostmap_t *nat_hostmap (ipnat_t *, struct in_addr, struct in_addr); static void nat_hostmapdel (struct hostmap *); static void nat_mssclamp (tcphdr_t *, u_32_t, fr_info_t *, u_short *); int nat_init() { KMALLOCS(nat_table[0], nat_t **, sizeof(nat_t *) * ipf_nattable_sz); if (nat_table[0] != NULL) bzero((char *)nat_table[0], ipf_nattable_sz * sizeof(nat_t *)); else return -1; KMALLOCS(nat_table[1], nat_t **, sizeof(nat_t *) * ipf_nattable_sz); if (nat_table[1] != NULL) bzero((char *)nat_table[1], ipf_nattable_sz * sizeof(nat_t *)); else return -1; KMALLOCS(nat_rules, ipnat_t **, sizeof(ipnat_t *) * ipf_natrules_sz); if (nat_rules != NULL) bzero((char *)nat_rules, ipf_natrules_sz * sizeof(ipnat_t *)); else return -1; KMALLOCS(rdr_rules, ipnat_t **, sizeof(ipnat_t *) * ipf_rdrrules_sz); if (rdr_rules != NULL) bzero((char *)rdr_rules, ipf_rdrrules_sz * sizeof(ipnat_t *)); else return -1; KMALLOCS(maptable, hostmap_t **, sizeof(hostmap_t *) * ipf_hostmap_sz); if (maptable != NULL) bzero((char *)maptable, sizeof(hostmap_t *) * ipf_hostmap_sz); else return -1; return 0; } static void nat_addrdr(n) ipnat_t *n; { ipnat_t **np; u_32_t j; u_int hv; int k; k = countbits(n->in_outmsk); if ((k >= 0) && (k != 32)) rdr_masks |= 1 << k; j = (n->in_outip & n->in_outmsk); hv = NAT_HASH_FN(j, 0, ipf_rdrrules_sz); np = rdr_rules + hv; while (*np != NULL) np = &(*np)->in_rnext; n->in_rnext = NULL; n->in_prnext = np; *np = n; } static void nat_addnat(n) ipnat_t *n; { ipnat_t **np; u_32_t j; u_int hv; int k; k = countbits(n->in_inmsk); if ((k >= 0) && (k != 32)) nat_masks |= 1 << k; j = (n->in_inip & n->in_inmsk); hv = NAT_HASH_FN(j, 0, ipf_natrules_sz); np = nat_rules + hv; while (*np != NULL) np = &(*np)->in_mnext; n->in_mnext = NULL; n->in_pmnext = np; *np = n; } static void nat_delrdr(n) ipnat_t *n; { if (n->in_rnext) n->in_rnext->in_prnext = n->in_prnext; *n->in_prnext = n->in_rnext; } static void nat_delnat(n) ipnat_t *n; { if (n->in_mnext) n->in_mnext->in_pmnext = n->in_pmnext; *n->in_pmnext = n->in_mnext; } /* * check if an ip address has already been allocated for a given mapping that * is not doing port based translation. * * Must be called with ipf_nat held as a write lock. */ static struct hostmap *nat_hostmap(np, real, map) ipnat_t *np; struct in_addr real; struct in_addr map; { hostmap_t *hm; u_int hv; hv = real.s_addr % HOSTMAP_SIZE; for (hm = maptable[hv]; hm; hm = hm->hm_next) if ((hm->hm_realip.s_addr == real.s_addr) && (np == hm->hm_ipnat)) { hm->hm_ref++; return hm; } KMALLOC(hm, hostmap_t *); if (hm) { hm->hm_next = maptable[hv]; hm->hm_pnext = maptable + hv; if (maptable[hv]) maptable[hv]->hm_pnext = &hm->hm_next; maptable[hv] = hm; hm->hm_ipnat = np; hm->hm_realip = real; hm->hm_mapip = map; hm->hm_ref = 1; } return hm; } /* * Must be called with ipf_nat held as a write lock. */ static void nat_hostmapdel(hm) struct hostmap *hm; { ATOMIC_DEC32(hm->hm_ref); if (hm->hm_ref == 0) { if (hm->hm_next) hm->hm_next->hm_pnext = hm->hm_pnext; *hm->hm_pnext = hm->hm_next; KFREE(hm); } } void fix_outcksum(fin, sp, n) fr_info_t *fin; u_short *sp; u_32_t n; { u_short sumshort; u_32_t sum1; if (!n) return; else if (n & NAT_HW_CKSUM) { n &= 0xffff; n += fin->fin_dlen; n = (n & 0xffff) + (n >> 16); *sp = n & 0xffff; 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(fin, sp, n) fr_info_t *fin; u_short *sp; u_32_t n; { u_short sumshort; u_32_t sum1; if (!n) return; else if (n & NAT_HW_CKSUM) { n &= 0xffff; n += fin->fin_dlen; n = (n & 0xffff) + (n >> 16); *sp = n & 0xffff; 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); } /* * fix_datacksum is used *only* for the adjustments of checksums in the data * section of an IP packet. * * The only situation in which you need to do this is when NAT'ing an * ICMP error message. Such a message, contains in its body the IP header * of the original IP packet, that causes the error. * * You can't use fix_incksum or fix_outcksum in that case, because for the * kernel the data section of the ICMP error is just data, and no special * processing like hardware cksum or ntohs processing have been done by the * kernel on the data section. */ void fix_datacksum(sp, n) u_short *sp; u_32_t n; { u_short sumshort; 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); } /* * 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(__DragonFly__) || defined(__NetBSD__) || defined(__OpenBSD__) || (__FreeBSD_version >= 300003) u_long cmd; #else int cmd; #endif caddr_t data; int mode; { ipnat_t *nat, *nt, *n = NULL, **np = NULL; int error = 0, ret, arg, getlock; ipnat_t natd; u_32_t i, j; #if (BSD >= 199306) && defined(_KERNEL) if ((securelevel >= 3) && (mode & FWRITE)) return EPERM; #endif nat = NULL; /* XXX gcc -Wuninitialized */ KMALLOC(nt, ipnat_t *); getlock = (mode & NAT_LOCKHELD) ? 0 : 1; if ((cmd == SIOCADNAT) || (cmd == SIOCRMNAT)) { if (mode & NAT_SYSSPACE) { bcopy(data, (char *)&natd, sizeof(natd)); error = 0; } else { error = IRCOPYPTR(data, (char *)&natd, sizeof(natd)); } } else if (cmd == SIOCIPFFL) { /* SIOCFLNAT & SIOCCNATL */ error = IRCOPY(data, (char *)&arg, sizeof(arg)); if (error) error = EFAULT; } if (error) goto done; /* * For add/delete, look to see if the NAT entry is already present */ if (getlock == 1) { WRITE_ENTER(&ipf_nat); } if ((cmd == SIOCADNAT) || (cmd == SIOCRMNAT)) { nat = &natd; nat->in_flags &= IPN_USERFLAGS; if ((nat->in_redir & NAT_MAPBLK) == 0) { if ((nat->in_flags & IPN_SPLIT) == 0) nat->in_inip &= nat->in_inmsk; if ((nat->in_flags & IPN_IPRANGE) == 0) 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)) { if (n->in_redir == NAT_REDIRECT && n->in_pnext != nat->in_pnext) continue; break; } } switch (cmd) { #ifdef IPFILTER_LOG case SIOCIPFFB : { int tmp; if (!(mode & FWRITE)) error = EPERM; else { tmp = ipflog_clear(IPL_LOGNAT); IWCOPY((char *)&tmp, (char *)data, sizeof(tmp)); } break; } #endif case SIOCADNAT : if (!(mode & FWRITE)) { error = EPERM; break; } if (n) { error = EEXIST; break; } if (nt == NULL) { error = ENOMEM; break; } n = nt; nt = NULL; bcopy((char *)nat, (char *)n, sizeof(*n)); n->in_ifp = (void *)GETUNIT(n->in_ifname, 4); if (!n->in_ifp) n->in_ifp = (void *)-1; if (n->in_plabel[0] != '\0') { n->in_apr = appr_lookup(n->in_p, n->in_plabel); if (!n->in_apr) { error = ENOENT; break; } } n->in_next = NULL; *np = n; if (n->in_redir & NAT_REDIRECT) { n->in_flags &= ~IPN_NOTDST; nat_addrdr(n); } if (n->in_redir & (NAT_MAP|NAT_MAPBLK)) { n->in_flags &= ~IPN_NOTSRC; nat_addnat(n); } n->in_use = 0; if (n->in_redir & NAT_MAPBLK) n->in_space = USABLE_PORTS * ~ntohl(n->in_outmsk); else if (n->in_flags & IPN_AUTOPORTMAP) n->in_space = USABLE_PORTS * ~ntohl(n->in_inmsk); else if (n->in_flags & IPN_IPRANGE) n->in_space = ntohl(n->in_outmsk) - ntohl(n->in_outip); else if (n->in_flags & IPN_SPLIT) n->in_space = 2; else n->in_space = ~ntohl(n->in_outmsk); /* * Calculate the number of valid IP addresses in the output * mapping range. In all cases, the range is inclusive of * the start and ending IP addresses. * If to a CIDR address, lose 2: broadcast + network address * (so subtract 1) * If to a range, add one. * If to a single IP address, set to 1. */ if (n->in_space) { if ((n->in_flags & IPN_IPRANGE) != 0) n->in_space += 1; else n->in_space -= 1; } else n->in_space = 1; if ((n->in_outmsk != 0xffffffff) && (n->in_outmsk != 0) && ((n->in_flags & (IPN_IPRANGE|IPN_SPLIT)) == 0)) n->in_nip = ntohl(n->in_outip) + 1; else if ((n->in_flags & IPN_SPLIT) && (n->in_redir & NAT_REDIRECT)) n->in_nip = ntohl(n->in_inip); 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) + 1); /* * Because two different sources can map to * different destinations but use the same * local IP#/port #. * If the result is smaller than in_space, then * we may have wrapped around 32bits. */ i = n->in_inmsk; if ((i != 0) && (i != 0xffffffff)) { j = n->in_space * (~ntohl(i) + 1); if (j >= n->in_space) n->in_space = j; else n->in_space = 0xffffffff; } } /* * If no protocol is specified, multiple by 256. */ if ((n->in_flags & IPN_TCPUDP) == 0) { j = n->in_space * 256; if (j >= n->in_space) n->in_space = j; else n->in_space = 0xffffffff; } } /* Otherwise, these fields are preset */ n = NULL; nat_stats.ns_rules++; break; case SIOCRMNAT : if (!(mode & FWRITE)) { error = EPERM; n = NULL; break; } if (!n) { error = ESRCH; break; } if (n->in_redir & NAT_REDIRECT) nat_delrdr(n); if (n->in_redir & (NAT_MAPBLK|NAT_MAP)) nat_delnat(n); if (nat_list == NULL) { nat_masks = 0; rdr_masks = 0; } *np = n->in_next; if (!n->in_use) { if (n->in_apr) appr_free(n->in_apr); KFREE(n); 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; nat_stats.ns_maptable = maptable; nat_stats.ns_nattab_sz = ipf_nattable_sz; nat_stats.ns_rultab_sz = ipf_natrules_sz; nat_stats.ns_rdrtab_sz = ipf_rdrrules_sz; nat_stats.ns_hostmap_sz = ipf_hostmap_sz; nat_stats.ns_instances = nat_instances; nat_stats.ns_apslist = ap_sess_list; error = IWCOPYPTR((char *)&nat_stats, (char *)data, sizeof(nat_stats)); break; case SIOCGNATL : { natlookup_t nl; MUTEX_DOWNGRADE(&ipf_nat); error = IRCOPYPTR((char *)data, (char *)&nl, sizeof(nl)); if (error) break; if (nat_lookupredir(&nl)) { error = IWCOPYPTR((char *)&nl, (char *)data, sizeof(nl)); } else error = ESRCH; break; } case SIOCIPFFL : /* old SIOCFLNAT & SIOCCNATL */ if (!(mode & FWRITE)) { error = EPERM; break; } error = 0; if (arg == 0) ret = nat_flushtable(); else if (arg == 1) ret = nat_clearlist(); else error = EINVAL; MUTEX_DOWNGRADE(&ipf_nat); if (!error) { error = IWCOPY((caddr_t)&ret, data, sizeof(ret)); if (error) error = EFAULT; } break; case SIOCSTLCK : error = IRCOPY(data, (caddr_t)&arg, sizeof(arg)); if (!error) { error = IWCOPY((caddr_t)&fr_nat_lock, data, sizeof(fr_nat_lock)); if (!error) fr_nat_lock = arg; } else error = EFAULT; break; case SIOCSTPUT : if (fr_nat_lock) error = fr_natputent(data); else error = EACCES; break; case SIOCSTGSZ : if (fr_nat_lock) error = fr_natgetsz(data); else error = EACCES; break; case SIOCSTGET : if (fr_nat_lock) error = fr_natgetent(data); else error = EACCES; break; case FIONREAD : #ifdef IPFILTER_LOG arg = (int)iplused[IPL_LOGNAT]; MUTEX_DOWNGRADE(&ipf_nat); error = IWCOPY((caddr_t)&arg, (caddr_t)data, sizeof(arg)); if (error) error = EFAULT; #endif break; default : error = EINVAL; break; } if (getlock == 1) { RWLOCK_EXIT(&ipf_nat); /* READ/WRITE */ } done: if (nt) KFREE(nt); return error; } static int fr_natgetsz(data) caddr_t data; { ap_session_t *aps; nat_t *nat, *n; int error = 0; natget_t ng; error = IRCOPY(data, (caddr_t)&ng, sizeof(ng)); if (error) return EFAULT; nat = ng.ng_ptr; if (!nat) { nat = nat_instances; ng.ng_sz = 0; if (nat == NULL) { error = IWCOPY((caddr_t)&ng, data, sizeof(ng)); if (error) error = EFAULT; return error; } } else { /* * Make sure the pointer we're copying from exists in the * current list of entries. Security precaution to prevent * copying of random kernel data. */ for (n = nat_instances; n; n = n->nat_next) if (n == nat) break; if (!n) return ESRCH; } ng.ng_sz = sizeof(nat_save_t); aps = nat->nat_aps; if ((aps != NULL) && (aps->aps_data != 0)) { ng.ng_sz += sizeof(ap_session_t); ng.ng_sz += aps->aps_psiz; if (aps->aps_psiz > 4) /* XXX - sizeof(ipn_data) */ ng.ng_sz -= 4; } error = IWCOPY((caddr_t)&ng, data, sizeof(ng)); if (error) error = EFAULT; return error; } static int fr_natgetent(data) caddr_t data; { nat_save_t ipn, *ipnp, *ipnn = NULL; nat_t *n, *nat; ap_session_t *aps; size_t dsz; int error; error = IRCOPY(data, (caddr_t)&ipnp, sizeof(ipnp)); if (error) return EFAULT; error = IRCOPY((caddr_t)ipnp, (caddr_t)&ipn, sizeof(ipn)); if (error) return EFAULT; nat = ipn.ipn_next; if (!nat) { nat = nat_instances; if (nat == NULL) { if (nat_instances == NULL) return ENOENT; return 0; } } else { /* * Make sure the pointer we're copying from exists in the * current list of entries. Security precaution to prevent * copying of random kernel data. */ for (n = nat_instances; n; n = n->nat_next) if (n == nat) break; if (!n) return ESRCH; } ipn.ipn_next = nat->nat_next; bcopy((char *)nat, (char *)&ipn.ipn_nat, sizeof(ipn.ipn_nat)); ipn.ipn_nat.nat_data = NULL; if (nat->nat_ptr) { bcopy((char *)nat->nat_ptr, (char *)&ipn.ipn_ipnat, sizeof(ipn.ipn_ipnat)); } if (nat->nat_fr) bcopy((char *)nat->nat_fr, (char *)&ipn.ipn_rule, sizeof(ipn.ipn_rule)); if ((aps = nat->nat_aps)) { dsz = sizeof(*aps); if (aps->aps_data) dsz += aps->aps_psiz; ipn.ipn_dsize = dsz; if (dsz > sizeof(ipn.ipn_data)) dsz -= sizeof(ipn.ipn_data); KMALLOCS(ipnn, nat_save_t *, sizeof(*ipnn) + dsz); if (ipnn == NULL) return ENOMEM; bcopy((char *)&ipn, (char *)ipnn, sizeof(ipn)); bcopy((char *)aps, (char *)ipnn->ipn_data, sizeof(*aps)); if (aps->aps_data) { bcopy(aps->aps_data, ipnn->ipn_data + sizeof(*aps), aps->aps_psiz); } error = IWCOPY((caddr_t)ipnn, ipnp, sizeof(ipn) + dsz); if (error) error = EFAULT; KFREES(ipnn, sizeof(*ipnn) + dsz); } else { ipn.ipn_dsize = 0; error = IWCOPY((caddr_t)&ipn, ipnp, sizeof(ipn)); if (error) error = EFAULT; } return error; } static int fr_natputent(data) caddr_t data; { nat_save_t ipn, *ipnp, *ipnn = NULL; nat_t *n, *nat; ap_session_t *aps; frentry_t *fr; ipnat_t *in; int error; error = IRCOPY(data, (caddr_t)&ipnp, sizeof(ipnp)); if (error) return EFAULT; error = IRCOPY((caddr_t)ipnp, (caddr_t)&ipn, sizeof(ipn)); if (error) return EFAULT; nat = NULL; if (ipn.ipn_dsize) { KMALLOCS(ipnn, nat_save_t *, sizeof(*ipnn) + ipn.ipn_dsize); if (ipnn == NULL) return ENOMEM; bcopy((char *)&ipn, (char *)ipnn, sizeof(ipn)); error = IRCOPY((caddr_t)ipnp + offsetof(nat_save_t, ipn_data), (caddr_t)ipnn->ipn_data, ipn.ipn_dsize); if (error) { error = EFAULT; goto junkput; } } else ipnn = NULL; KMALLOC(nat, nat_t *); if (nat == NULL) { error = EFAULT; goto junkput; } bcopy((char *)&ipn.ipn_nat, (char *)nat, sizeof(*nat)); /* * Initialize all these so that nat_delete() doesn't cause a crash. */ nat->nat_phnext[0] = NULL; nat->nat_phnext[1] = NULL; fr = nat->nat_fr; nat->nat_fr = NULL; aps = nat->nat_aps; nat->nat_aps = NULL; in = nat->nat_ptr; nat->nat_ptr = NULL; nat->nat_hm = NULL; nat->nat_data = NULL; nat->nat_ifp = GETUNIT(nat->nat_ifname, 4); /* * Restore the rule associated with this nat session */ if (in) { KMALLOC(in, ipnat_t *); if (in == NULL) { error = ENOMEM; goto junkput; } nat->nat_ptr = in; bcopy((char *)&ipn.ipn_ipnat, (char *)in, sizeof(*in)); in->in_use = 1; in->in_flags |= IPN_DELETE; in->in_next = NULL; in->in_rnext = NULL; in->in_prnext = NULL; in->in_mnext = NULL; in->in_pmnext = NULL; in->in_ifp = GETUNIT(in->in_ifname, 4); if (in->in_plabel[0] != '\0') { in->in_apr = appr_lookup(in->in_p, in->in_plabel); } } /* * Restore ap_session_t structure. Include the private data allocated * if it was there. */ if (aps) { KMALLOC(aps, ap_session_t *); if (aps == NULL) { error = ENOMEM; goto junkput; } nat->nat_aps = aps; aps->aps_next = ap_sess_list; ap_sess_list = aps; bcopy(ipnn->ipn_data, (char *)aps, sizeof(*aps)); if (in) aps->aps_apr = in->in_apr; if (aps->aps_psiz) { KMALLOCS(aps->aps_data, void *, aps->aps_psiz); if (aps->aps_data == NULL) { error = ENOMEM; goto junkput; } bcopy(ipnn->ipn_data + sizeof(*aps), aps->aps_data, aps->aps_psiz); } else { aps->aps_psiz = 0; aps->aps_data = NULL; } } /* * If there was a filtering rule associated with this entry then * build up a new one. */ if (fr != NULL) { if (nat->nat_flags & FI_NEWFR) { KMALLOC(fr, frentry_t *); nat->nat_fr = fr; if (fr == NULL) { error = ENOMEM; goto junkput; } bcopy((char *)&ipn.ipn_fr, (char *)fr, sizeof(*fr)); ipn.ipn_nat.nat_fr = fr; error = IWCOPY((caddr_t)&ipn, ipnp, sizeof(ipn)); if (error) { error = EFAULT; goto junkput; } } else { for (n = nat_instances; n; n = n->nat_next) if (n->nat_fr == fr) break; if (!n) { error = ESRCH; goto junkput; } } } if (ipnn) KFREES(ipnn, sizeof(ipn) + ipn.ipn_dsize); nat_insert(nat); return 0; junkput: if (ipnn) KFREES(ipnn, sizeof(ipn) + ipn.ipn_dsize); if (nat) nat_delete(nat); return error; } /* * Delete a nat entry from the various lists and table. */ static void nat_delete(natd) struct nat *natd; { struct ipnat *ipn; if (natd->nat_flags & FI_WILDP) nat_stats.ns_wilds--; if (natd->nat_hnext[0]) natd->nat_hnext[0]->nat_phnext[0] = natd->nat_phnext[0]; *natd->nat_phnext[0] = natd->nat_hnext[0]; if (natd->nat_hnext[1]) natd->nat_hnext[1]->nat_phnext[1] = natd->nat_phnext[1]; *natd->nat_phnext[1] = natd->nat_hnext[1]; if (natd->nat_me != NULL) *natd->nat_me = NULL; if (natd->nat_fr != NULL) { ATOMIC_DEC32(natd->nat_fr->fr_ref); } if (natd->nat_hm != NULL) nat_hostmapdel(natd->nat_hm); /* * 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. */ ipn = natd->nat_ptr; if (ipn != NULL) { ipn->in_space++; ipn->in_use--; if (!ipn->in_use && (ipn->in_flags & IPN_DELETE)) { if (ipn->in_apr) appr_free(ipn->in_apr); KFREE(ipn); nat_stats.ns_rules--; } } MUTEX_DESTROY(&natd->nat_lock); /* * If there's a fragment table entry too for this nat entry, then * dereference that as well. */ ipfr_forgetnat((void *)natd); aps_free(natd->nat_aps); nat_stats.ns_inuse--; KFREE(natd); } /* * nat_flushtable - clear the NAT table of all mapping entries. * (this is for the dynamic mappings) */ static int nat_flushtable() { nat_t *nat, **natp; int j = 0; /* * ALL NAT mappings deleted, so lets just make the deletions * quicker. */ if (nat_table[0] != NULL) bzero((char *)nat_table[0], sizeof(nat_table[0]) * ipf_nattable_sz); if (nat_table[1] != NULL) bzero((char *)nat_table[1], sizeof(nat_table[1]) * ipf_nattable_sz); for (natp = &nat_instances; (nat = *natp); ) { *natp = nat->nat_next; #ifdef IPFILTER_LOG nat_log(nat, NL_FLUSH); #endif nat_delete(nat); j++; } nat_stats.ns_inuse = 0; return j; } /* * nat_clearlist - delete all rules in the active NAT mapping list. * (this is for NAT/RDR rules) */ int nat_clearlist() { ipnat_t *n, **np = &nat_list; int i = 0; if (nat_rules != NULL) bzero((char *)nat_rules, sizeof(*nat_rules) * ipf_natrules_sz); if (rdr_rules != NULL) bzero((char *)rdr_rules, sizeof(*rdr_rules) * ipf_rdrrules_sz); while ((n = *np)) { *np = n->in_next; if (!n->in_use) { if (n->in_apr) appr_free(n->in_apr); KFREE(n); nat_stats.ns_rules--; } else { n->in_flags |= IPN_DELETE; n->in_next = NULL; } i++; } nat_masks = 0; rdr_masks = 0; return i; } /* * Create a new NAT table entry. * NOTE: Assumes write lock on ipf_nat has been obtained already. * If you intend on changing this, beware: appr_new() may call nat_new() * recursively! */ nat_t *nat_new(fin, ip, np, natsave, flags, direction) fr_info_t *fin; ip_t *ip; ipnat_t *np; nat_t **natsave; u_int flags; int direction; { u_32_t sum1, sum2, sumd, l; u_short port = 0, sport = 0, dport = 0, nport = 0; struct in_addr in, inb; u_short nflags, sp, dp; tcphdr_t *tcp = NULL; hostmap_t *hm = NULL; nat_t *nat, *natl; #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6) qif_t *qf = fin->fin_qif; #endif if (nat_stats.ns_inuse >= ipf_nattable_max) { nat_stats.ns_memfail++; return NULL; } nflags = flags & np->in_flags; if (flags & IPN_TCPUDP) { tcp = (tcphdr_t *)fin->fin_dp; sport = htons(fin->fin_data[0]); dport = htons(fin->fin_data[1]); } /* Give me a new nat */ KMALLOC(nat, nat_t *); if (nat == NULL) { nat_stats.ns_memfail++; /* * Try to automatically tune the max # of entries in the * table allowed to be less than what will cause kmem_alloc() * to fail and try to eliminate panics due to out of memory * conditions arising. */ if (ipf_nattable_max > ipf_nattable_sz) { ipf_nattable_max = nat_stats.ns_inuse - 100; printf("ipf_nattable_max reduced to %d\n", ipf_nattable_max); } return NULL; } bzero((char *)nat, sizeof(*nat)); nat->nat_tcpstate[0] = TCPS_CLOSED; nat->nat_tcpstate[1] = TCPS_CLOSED; nat->nat_flags = flags; if (flags & FI_WILDP) nat_stats.ns_wilds++; /* * Search the current table for a match. */ if (direction == NAT_OUTBOUND) { /* * Values at which the search for a free resouce starts. */ u_32_t st_ip; u_short st_port; /* * If it's an outbound packet which doesn't match any existing * record, then create a new port */ l = 0; st_ip = np->in_nip; st_port = np->in_pnext; do { port = 0; in.s_addr = htonl(np->in_nip); if (l == 0) { /* * Check to see if there is an existing NAT * setup for this IP address pair. */ hm = nat_hostmap(np, fin->fin_src, in); if (hm != NULL) in.s_addr = hm->hm_mapip.s_addr; } else if ((l == 1) && (hm != NULL)) { nat_hostmapdel(hm); hm = NULL; } in.s_addr = ntohl(in.s_addr); nat->nat_hm = hm; if ((np->in_outmsk == 0xffffffff) && (np->in_pnext == 0)) { if (l > 0) goto badnat; } if (np->in_redir & NAT_MAPBLK) { if ((l >= np->in_ppip) || ((l > 0) && !(flags & IPN_TCPUDP))) goto badnat; /* * map-block - Calculate destination address. */ in.s_addr = ntohl(fin->fin_saddr); in.s_addr &= ntohl(~np->in_inmsk); inb.s_addr = in.s_addr; in.s_addr /= np->in_ippip; in.s_addr &= ntohl(~np->in_outmsk); in.s_addr += ntohl(np->in_outip); /* * Calculate destination port. */ if ((flags & IPN_TCPUDP) && (np->in_ppip != 0)) { port = ntohs(sport) + l; port %= np->in_ppip; port += np->in_ppip * (inb.s_addr % np->in_ippip); port += MAPBLK_MINPORT; port = htons(port); } } else if (!np->in_outip && (np->in_outmsk == 0xffffffff)) { /* * 0/32 - use the interface's IP address. */ if ((l > 0) || fr_ifpaddr(4, fin->fin_ifp, &in) == -1) goto badnat; in.s_addr = ntohl(in.s_addr); } else if (!np->in_outip && !np->in_outmsk) { /* * 0/0 - use the original source address/port. */ if (l > 0) goto badnat; in.s_addr = ntohl(fin->fin_saddr); } else if ((np->in_outmsk != 0xffffffff) && (np->in_pnext == 0) && ((l > 0) || (hm == NULL))) np->in_nip++; natl = NULL; if ((nflags & IPN_TCPUDP) && ((np->in_redir & NAT_MAPBLK) == 0) && (np->in_flags & IPN_AUTOPORTMAP)) { if ((l > 0) && (l % np->in_ppip == 0)) { if (l > np->in_space) { goto badnat; } else if ((l > np->in_ppip) && np->in_outmsk != 0xffffffff) np->in_nip++; } if (np->in_ppip != 0) { port = ntohs(sport); port += (l % np->in_ppip); port %= np->in_ppip; port += np->in_ppip * (ntohl(fin->fin_saddr) % np->in_ippip); port += MAPBLK_MINPORT; port = htons(port); } } else if (((np->in_redir & NAT_MAPBLK) == 0) && (nflags & IPN_TCPUDP) && (np->in_pnext != 0)) { port = htons(np->in_pnext++); if (np->in_pnext > ntohs(np->in_pmax)) { np->in_pnext = ntohs(np->in_pmin); if (np->in_outmsk != 0xffffffff) np->in_nip++; } } if (np->in_flags & IPN_IPRANGE) { if (np->in_nip > ntohl(np->in_outmsk)) np->in_nip = ntohl(np->in_outip); } else { if ((np->in_outmsk != 0xffffffff) && ((np->in_nip + 1) & ntohl(np->in_outmsk)) > ntohl(np->in_outip)) np->in_nip = ntohl(np->in_outip) + 1; } if (!port && (flags & IPN_TCPUDP)) port = sport; /* * Here we do a lookup of the connection as seen from * the outside. If an IP# pair already exists, try * again. So if you have A->B becomes C->B, you can * also have D->E become C->E but not D->B causing * another C->B. Also take protocol and ports into * account when determining whether a pre-existing * NAT setup will cause an external conflict where * this is appropriate. */ inb.s_addr = htonl(in.s_addr); sp = fin->fin_data[0]; dp = fin->fin_data[1]; fin->fin_data[0] = fin->fin_data[1]; fin->fin_data[1] = htons(port); natl = nat_inlookup(fin, flags & ~FI_WILDP, (u_int)fin->fin_p, fin->fin_dst, inb, 1); fin->fin_data[0] = sp; fin->fin_data[1] = dp; /* * Has the search wrapped around and come back to the * start ? */ if ((natl != NULL) && (np->in_pnext != 0) && (st_port == np->in_pnext) && (np->in_nip != 0) && (st_ip == np->in_nip)) goto badnat; l++; } while (natl != NULL); if (np->in_space > 0) np->in_space--; /* Setup the NAT table */ nat->nat_inip = fin->fin_src; nat->nat_outip.s_addr = htonl(in.s_addr); nat->nat_oip = fin->fin_dst; if (nat->nat_hm == NULL) nat->nat_hm = nat_hostmap(np, fin->fin_src, nat->nat_outip); sum1 = LONG_SUM(ntohl(fin->fin_saddr)) + ntohs(sport); sum2 = LONG_SUM(in.s_addr) + ntohs(port); if (flags & IPN_TCPUDP) { nat->nat_inport = sport; nat->nat_outport = port; /* sport */ 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. */ if (np->in_flags & IPN_SPLIT) { in.s_addr = np->in_nip; if (np->in_inip == htonl(in.s_addr)) np->in_nip = ntohl(np->in_inmsk); else { np->in_nip = ntohl(np->in_inip); if (np->in_flags & IPN_ROUNDR) { nat_delrdr(np); nat_addrdr(np); } } } else { in.s_addr = ntohl(np->in_inip); if (np->in_flags & IPN_ROUNDR) { nat_delrdr(np); nat_addrdr(np); } } if (!np->in_pnext) nport = dport; else { /* * Whilst not optimized for the case where * pmin == pmax, the gain is not significant. */ if (np->in_pmin != np->in_pmax) { nport = ntohs(dport) - ntohs(np->in_pmin) + ntohs(np->in_pnext); nport = ntohs(nport); } else nport = np->in_pnext; } /* * When the redirect-to address is set to 0.0.0.0, just * assume a blank `forwarding' of the packet. */ if (in.s_addr == 0) in.s_addr = ntohl(fin->fin_daddr); nat->nat_inip.s_addr = htonl(in.s_addr); nat->nat_outip = fin->fin_dst; nat->nat_oip = fin->fin_src; sum1 = LONG_SUM(ntohl(fin->fin_daddr)) + ntohs(dport); sum2 = LONG_SUM(in.s_addr) + ntohs(nport); if (flags & IPN_TCPUDP) { nat->nat_inport = nport; nat->nat_outport = dport; nat->nat_oport = sport; } } CALC_SUMD(sum1, sum2, sumd); nat->nat_sumd[0] = (sumd & 0xffff) + (sumd >> 16); #if SOLARIS && defined(_KERNEL) && (SOLARIS2 >= 6) if ((flags & IPN_TCP) && dohwcksum && (qf->qf_ill->ill_ick.ick_magic == ICK_M_CTL_MAGIC)) { if (direction == NAT_OUTBOUND) sum1 = LONG_SUM(ntohl(in.s_addr)); else sum1 = LONG_SUM(ntohl(fin->fin_saddr)); sum1 += LONG_SUM(ntohl(fin->fin_daddr)); sum1 += IPPROTO_TCP; sum1 = (sum1 & 0xffff) + (sum1 >> 16); nat->nat_sumd[1] = NAT_HW_CKSUM|(sum1 & 0xffff); } else #endif nat->nat_sumd[1] = nat->nat_sumd[0]; if ((flags & IPN_TCPUDP) && ((sport != port) || (dport != nport))) { if (direction == NAT_OUTBOUND) sum1 = LONG_SUM(ntohl(fin->fin_saddr)); else sum1 = LONG_SUM(ntohl(fin->fin_daddr)); sum2 = LONG_SUM(in.s_addr); CALC_SUMD(sum1, sum2, sumd); nat->nat_ipsumd = (sumd & 0xffff) + (sumd >> 16); } else nat->nat_ipsumd = nat->nat_sumd[0]; in.s_addr = htonl(in.s_addr); strncpy(nat->nat_ifname, IFNAME(fin->fin_ifp), IFNAMSIZ); nat->nat_me = natsave; nat->nat_dir = direction; nat->nat_ifp = fin->fin_ifp; nat->nat_ptr = np; nat->nat_p = fin->fin_p; nat->nat_bytes = 0; nat->nat_pkts = 0; nat->nat_mssclamp = np->in_mssclamp; nat->nat_fr = fin->fin_fr; if (nat->nat_fr != NULL) { ATOMIC_INC32(nat->nat_fr->fr_ref); } if (direction == NAT_OUTBOUND) { if (flags & IPN_TCPUDP) tcp->th_sport = port; } else { if (flags & IPN_TCPUDP) tcp->th_dport = nport; } nat_insert(nat); if ((np->in_apr != NULL) && (np->in_dport == 0 || (tcp != NULL && dport == np->in_dport))) (void) appr_new(fin, ip, nat); np->in_use++; #ifdef IPFILTER_LOG nat_log(nat, (u_int)np->in_redir); #endif return nat; badnat: nat_stats.ns_badnat++; if ((hm = nat->nat_hm) != NULL) nat_hostmapdel(hm); KFREE(nat); return NULL; } /* * Insert a NAT entry into the hash tables for searching and add it to the * list of active NAT entries. Adjust global counters when complete. */ void nat_insert(nat) nat_t *nat; { u_int hv1, hv2; nat_t **natp; MUTEX_INIT(&nat->nat_lock, "nat entry lock", NULL); nat->nat_age = fr_defnatage; nat->nat_ifname[sizeof(nat->nat_ifname) - 1] = '\0'; if (nat->nat_ifname[0] !='\0') { nat->nat_ifp = GETUNIT(nat->nat_ifname, 4); } nat->nat_next = nat_instances; nat_instances = nat; if (!(nat->nat_flags & (FI_W_SPORT|FI_W_DPORT))) { hv1 = NAT_HASH_FN(nat->nat_inip.s_addr, nat->nat_inport, 0xffffffff); hv1 = NAT_HASH_FN(nat->nat_oip.s_addr, hv1 + nat->nat_oport, ipf_nattable_sz); hv2 = NAT_HASH_FN(nat->nat_outip.s_addr, nat->nat_outport, 0xffffffff); hv2 = NAT_HASH_FN(nat->nat_oip.s_addr, hv2 + nat->nat_oport, ipf_nattable_sz); } else { hv1 = NAT_HASH_FN(nat->nat_oip.s_addr, nat->nat_inip.s_addr, ipf_nattable_sz); hv2 = NAT_HASH_FN(nat->nat_oip.s_addr, nat->nat_outip.s_addr, ipf_nattable_sz); } natp = &nat_table[0][hv1]; if (*natp) (*natp)->nat_phnext[0] = &nat->nat_hnext[0]; nat->nat_phnext[0] = natp; nat->nat_hnext[0] = *natp; *natp = nat; natp = &nat_table[1][hv2]; if (*natp) (*natp)->nat_phnext[1] = &nat->nat_hnext[1]; nat->nat_phnext[1] = natp; nat->nat_hnext[1] = *natp; *natp = nat; nat_stats.ns_added++; nat_stats.ns_inuse++; } nat_t *nat_icmplookup(ip, fin, dir) ip_t *ip; fr_info_t *fin; int dir; { icmphdr_t *icmp; tcphdr_t *tcp = NULL; ip_t *oip; int flags = 0, type, minlen; 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 < ICMPERR_MINPKTLEN)) 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); minlen = (oip->ip_hl << 2); if (minlen < sizeof(ip_t)) return NULL; if (ip->ip_len < ICMPERR_IPICMPHLEN + minlen) return NULL; /* * Is the buffer big enough for all of it ? It's the size of the IP * header claimed in the encapsulated part which is of concern. It * may be too big to be in this buffer but not so big that it's * outside the ICMP packet, leading to TCP deref's causing problems. * This is possible because we don't know how big oip_hl is when we * do the pullup early in fr_check() and thus can't gaurantee it is * all here now. */ #ifdef _KERNEL { mb_t *m; # if SOLARIS m = fin->fin_qfm; if ((char *)oip + fin->fin_dlen - ICMPERR_ICMPHLEN > (char *)m->b_wptr) return NULL; # else m = *(mb_t **)fin->fin_mp; if ((char *)oip + fin->fin_dlen - ICMPERR_ICMPHLEN > (char *)ip + m->m_len) return NULL; # endif } #endif if (oip->ip_p == IPPROTO_TCP) flags = IPN_TCP; else if (oip->ip_p == IPPROTO_UDP) flags = IPN_UDP; if (flags & IPN_TCPUDP) { u_short data[2]; nat_t *nat; minlen += 8; /* + 64bits of data to get ports */ if (ip->ip_len < ICMPERR_IPICMPHLEN + minlen) return NULL; data[0] = fin->fin_data[0]; data[1] = fin->fin_data[1]; tcp = (tcphdr_t *)((char *)oip + (oip->ip_hl << 2)); fin->fin_data[0] = ntohs(tcp->th_dport); fin->fin_data[1] = ntohs(tcp->th_sport); if (dir == NAT_INBOUND) { nat = nat_inlookup(fin, flags, (u_int)oip->ip_p, oip->ip_dst, oip->ip_src, 0); } else { nat = nat_outlookup(fin, flags, (u_int)oip->ip_p, oip->ip_dst, oip->ip_src, 0); } fin->fin_data[0] = data[0]; fin->fin_data[1] = data[1]; return nat; } if (dir == NAT_INBOUND) return nat_inlookup(fin, 0, (u_int)oip->ip_p, oip->ip_dst, oip->ip_src, 0); else return nat_outlookup(fin, 0, (u_int)oip->ip_p, oip->ip_dst, oip->ip_src, 0); } /* * This should *ONLY* be used for incoming packets to make sure a NAT'd ICMP * packet gets correctly recognised. */ nat_t *nat_icmp(ip, fin, nflags, dir) ip_t *ip; fr_info_t *fin; u_int *nflags; int dir; { u_32_t sum1, sum2, sumd, sumd2 = 0; struct in_addr in; int flags, dlen; icmphdr_t *icmp; udphdr_t *udp; tcphdr_t *tcp; nat_t *nat; ip_t *oip; if ((fin->fin_fl & FI_SHORT) || (fin->fin_off != 0)) return NULL; /* * nat_icmplookup() will return NULL for `defective' packets. */ if ((ip->ip_v != 4) || !(nat = nat_icmplookup(ip, fin, dir))) return NULL; flags = 0; sumd2 = 0; *nflags = IPN_ICMPERR; icmp = (icmphdr_t *)fin->fin_dp; oip = (ip_t *)&icmp->icmp_ip; if (oip->ip_p == IPPROTO_TCP) flags = IPN_TCP; else if (oip->ip_p == IPPROTO_UDP) flags = IPN_UDP; udp = (udphdr_t *)((((char *)oip) + (oip->ip_hl << 2))); dlen = ip->ip_len - ((char *)udp - (char *)ip); /* * XXX - what if this is bogus hl and we go off the end ? * In this case, nat_icmplookup() will have returned NULL. */ tcp = (tcphdr_t *)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 as 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#. */ /* * Step 1 * Fix the IP addresses in the offending IP packet. You also need * to adjust the IP header checksum of that offending IP packet * and the ICMP checksum of the ICMP error message itself. * * Unfortunately, for UDP and TCP, the IP addresses are also contained * in the pseudo header that is used to compute the UDP resp. TCP * checksum. So, we must compensate that as well. Even worse, the * change in the UDP and TCP checksums require yet another * adjustment of the ICMP checksum of the ICMP error message. * */ if (oip->ip_dst.s_addr == nat->nat_oip.s_addr) { sum1 = LONG_SUM(ntohl(oip->ip_src.s_addr)); in = nat->nat_inip; oip->ip_src = in; } else { sum1 = LONG_SUM(ntohl(oip->ip_dst.s_addr)); in = nat->nat_outip; oip->ip_dst = in; } sum2 = LONG_SUM(ntohl(in.s_addr)); CALC_SUMD(sum1, sum2, sumd); /* * Fix IP checksum of the offending IP packet to adjust for * the change in the IP address. * * Normally, you would expect that the ICMP checksum of the * ICMP error message needs to be adjusted as well for the * IP address change in oip. * However, this is a NOP, because the ICMP checksum is * calculated over the complete ICMP packet, which includes the * changed oip IP addresses and oip->ip_sum. However, these * two changes cancel each other out (if the delta for * the IP address is x, then the delta for ip_sum is minus x), * so no change in the icmp_cksum is necessary. * * Be careful that nat_dir refers to the direction of the * offending IP packet (oip), not to its ICMP response (icmp) */ fix_datacksum(&oip->ip_sum, sumd); /* Fix icmp cksum : IP Addr + Cksum */ /* * Fix UDP pseudo header checksum to compensate for the * IP address change. */ if ((oip->ip_p == IPPROTO_UDP) && (dlen >= 8) && udp->uh_sum) { /* * The UDP checksum is optional, only adjust it * if it has been set. */ sum1 = ntohs(udp->uh_sum); fix_datacksum(&udp->uh_sum, sumd); sum2 = ntohs(udp->uh_sum); /* * Fix ICMP checksum to compensate the UDP * checksum adjustment. */ sumd2 = sumd << 1; CALC_SUMD(sum1, sum2, sumd); sumd2 += sumd; } /* * Fix TCP pseudo header checksum to compensate for the * IP address change. Before we can do the change, we * must make sure that oip is sufficient large to hold * the TCP checksum (normally it does not!). */ else if ((oip->ip_p == IPPROTO_TCP) && (dlen >= 18)) { sum1 = ntohs(tcp->th_sum); fix_datacksum(&tcp->th_sum, sumd); sum2 = ntohs(tcp->th_sum); /* * Fix ICMP checksum to compensate the TCP * checksum adjustment. */ sumd2 = sumd << 1; CALC_SUMD(sum1, sum2, sumd); sumd2 += sumd; } else { sumd2 = (sumd >> 16); if (nat->nat_dir == NAT_OUTBOUND) sumd2 = ~sumd2; else sumd2 = ~sumd2 + 1; } if (((flags & IPN_TCPUDP) != 0) && (dlen >= 4)) { /* * Step 2 : * For offending TCP/UDP IP packets, translate the ports as * well, based on the NAT specification. Of course such * a change must be reflected in the ICMP checksum as well. * * Advance notice : Now it becomes complicated :-) * * Since the port fields are part of the TCP/UDP checksum * of the offending IP packet, you need to adjust that checksum * as well... but, if you change, you must change the icmp * checksum *again*, to reflect that change. * * To further complicate: the TCP checksum is not in the first * 8 bytes of the offending ip packet, so it most likely is not * available. Some OSses like Solaris return enough bytes to * include the TCP checksum. So we have to check if the * ip->ip_len actually holds the TCP checksum of the oip! */ if (nat->nat_oport == tcp->th_dport) { if (tcp->th_sport != nat->nat_inport) { /* * Fix ICMP checksum to compensate port * adjustment. */ sum1 = ntohs(nat->nat_inport); sum2 = ntohs(tcp->th_sport); tcp->th_sport = nat->nat_inport; /* * Fix udp checksum to compensate port * adjustment. NOTE : the offending IP packet * flows the other direction compared to the * ICMP message. * * The UDP checksum is optional, only adjust * it if it has been set. */ if ((oip->ip_p == IPPROTO_UDP) && (dlen >= 8) && udp->uh_sum) { sumd = sum1 - sum2; sumd2 += sumd; sum1 = ntohs(udp->uh_sum); fix_datacksum(&udp->uh_sum, sumd); sum2 = ntohs(udp->uh_sum); /* * Fix ICMP checksum to compensate * UDP checksum adjustment. */ CALC_SUMD(sum1, sum2, sumd); sumd2 += sumd; } /* * Fix tcp checksum (if present) to compensate * port adjustment. NOTE : the offending IP * packet flows the other direction compared to * the ICMP message. */ if (oip->ip_p == IPPROTO_TCP) { if (dlen >= 18) { sumd = sum1 - sum2; sumd2 += sumd; sum1 = ntohs(tcp->th_sum); fix_datacksum(&tcp->th_sum, sumd); sum2 = ntohs(tcp->th_sum); /* * Fix ICMP checksum to * compensate TCP checksum * adjustment. */ CALC_SUMD(sum1, sum2, sumd); sumd2 += sumd; } else { sumd = sum2 - sum1 + 1; sumd2 += sumd; } } } } else if (tcp->th_dport != nat->nat_outport) { /* * Fix ICMP checksum to compensate port * adjustment. */ sum1 = ntohs(nat->nat_outport); sum2 = ntohs(tcp->th_dport); tcp->th_dport = nat->nat_outport; /* * Fix udp checksum to compensate port * adjustment. NOTE : the offending IP * packet flows the other direction compared * to the ICMP message. * * The UDP checksum is optional, only adjust * it if it has been set. */ if ((oip->ip_p == IPPROTO_UDP) && (dlen >= 8) && udp->uh_sum) { sumd = sum1 - sum2; sumd2 += sumd; sum1 = ntohs(udp->uh_sum); fix_datacksum(&udp->uh_sum, sumd); sum2 = ntohs(udp->uh_sum); /* * Fix ICMP checksum to compensate * UDP checksum adjustment. */ CALC_SUMD(sum1, sum2, sumd); } /* * Fix tcp checksum (if present) to compensate * port adjustment. NOTE : the offending IP * packet flows the other direction compared to * the ICMP message. */ if (oip->ip_p == IPPROTO_TCP) { if (dlen >= 18) { sumd = sum1 - sum2; sumd2 += sumd; sum1 = ntohs(tcp->th_sum); fix_datacksum(&tcp->th_sum, sumd); sum2 = ntohs(tcp->th_sum); /* * Fix ICMP checksum to compensate * UDP checksum adjustment. */ CALC_SUMD(sum1, sum2, sumd); } else { sumd = sum2 - sum1; if (nat->nat_dir == NAT_OUTBOUND) sumd++; } } sumd2 += sumd; } if (sumd2) { sumd2 = (sumd2 & 0xffff) + (sumd2 >> 16); sumd2 = (sumd2 & 0xffff) + (sumd2 >> 16); fix_incksum(fin, &icmp->icmp_cksum, sumd2); } } if (oip->ip_p == IPPROTO_ICMP) 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. */ nat_t *nat_inlookup(fin, flags, p, src, mapdst, rw) fr_info_t *fin; u_int flags, p; struct in_addr src , mapdst; int rw; { u_short sport, dport; nat_t *nat; int nflags; u_32_t dst; ipnat_t *ipn; void *ifp; u_int hv; if (fin != NULL) ifp = fin->fin_ifp; else ifp = NULL; dst = mapdst.s_addr; if (flags & IPN_TCPUDP) { sport = htons(fin->fin_data[0]); dport = htons(fin->fin_data[1]); } else { sport = 0; dport = 0; } hv = NAT_HASH_FN(dst, dport, 0xffffffff); hv = NAT_HASH_FN(src.s_addr, hv + sport, ipf_nattable_sz); nat = nat_table[1][hv]; for (; nat; nat = nat->nat_hnext[1]) { nflags = nat->nat_flags; if ((!ifp || ifp == nat->nat_ifp) && nat->nat_oip.s_addr == src.s_addr && nat->nat_outip.s_addr == dst && ((p == 0) || (p == nat->nat_p))) { switch (p) { case IPPROTO_TCP : case IPPROTO_UDP : if (nat->nat_oport != sport) continue; if (nat->nat_outport != dport) continue; break; default : break; } ipn = nat->nat_ptr; if ((ipn != NULL) && (nat->nat_aps != NULL)) if (appr_match(fin, nat) != 0) continue; return nat; } } if (!nat_stats.ns_wilds || !(flags & FI_WILDP)) return NULL; if (!rw) { RWLOCK_EXIT(&ipf_nat); } hv = NAT_HASH_FN(dst, 0, 0xffffffff); hv = NAT_HASH_FN(src.s_addr, dst, ipf_nattable_sz); if (!rw) { WRITE_ENTER(&ipf_nat); } nat = nat_table[1][hv]; for (; nat; nat = nat->nat_hnext[1]) { nflags = nat->nat_flags; if (ifp && ifp != nat->nat_ifp) continue; if (!(nflags & FI_WILDP)) continue; if (nat->nat_oip.s_addr != src.s_addr || nat->nat_outip.s_addr != dst) continue; if (((nat->nat_oport == sport) || (nflags & FI_W_DPORT)) && ((nat->nat_outport == dport) || (nflags & FI_W_SPORT))) { nat_tabmove(fin, nat); break; } } if (!rw) { MUTEX_DOWNGRADE(&ipf_nat); } return nat; } /* * This function is only called for TCP/UDP NAT table entries where the * original was placed in the table without hashing on the ports and we now * want to include hashing on port numbers. */ static void nat_tabmove(fin, nat) fr_info_t *fin; nat_t *nat; { u_short sport, dport; u_int hv, nflags; nat_t **natp; nflags = nat->nat_flags; sport = ntohs(fin->fin_data[0]); dport = ntohs(fin->fin_data[1]); /* * Remove the NAT entry from the old location */ if (nat->nat_hnext[0]) nat->nat_hnext[0]->nat_phnext[0] = nat->nat_phnext[0]; *nat->nat_phnext[0] = nat->nat_hnext[0]; if (nat->nat_hnext[1]) nat->nat_hnext[1]->nat_phnext[1] = nat->nat_phnext[1]; *nat->nat_phnext[1] = nat->nat_hnext[1]; /* * Add into the NAT table in the new position */ hv = NAT_HASH_FN(nat->nat_inip.s_addr, sport, 0xffffffff); hv = NAT_HASH_FN(nat->nat_oip.s_addr, hv + dport, ipf_nattable_sz); natp = &nat_table[0][hv]; if (*natp) (*natp)->nat_phnext[0] = &nat->nat_hnext[0]; nat->nat_phnext[0] = natp; nat->nat_hnext[0] = *natp; *natp = nat; hv = NAT_HASH_FN(nat->nat_outip.s_addr, sport, 0xffffffff); hv = NAT_HASH_FN(nat->nat_oip.s_addr, hv + dport, ipf_nattable_sz); natp = &nat_table[1][hv]; if (*natp) (*natp)->nat_phnext[1] = &nat->nat_hnext[1]; nat->nat_phnext[1] = natp; nat->nat_hnext[1] = *natp; *natp = nat; } /* * 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(fin, flags, p, src, dst, rw) fr_info_t *fin; u_int flags, p; struct in_addr src , dst; int rw; { u_short sport, dport; nat_t *nat; int nflags; ipnat_t *ipn; u_32_t srcip; void *ifp; u_int hv; ifp = fin->fin_ifp; srcip = src.s_addr; if (flags & IPN_TCPUDP) { sport = ntohs(fin->fin_data[0]); dport = ntohs(fin->fin_data[1]); } else { sport = 0; dport = 0; } hv = NAT_HASH_FN(srcip, sport, 0xffffffff); hv = NAT_HASH_FN(dst.s_addr, hv + dport, ipf_nattable_sz); nat = nat_table[0][hv]; for (; nat; nat = nat->nat_hnext[0]) { nflags = nat->nat_flags; if ((!ifp || ifp == nat->nat_ifp) && nat->nat_inip.s_addr == srcip && nat->nat_oip.s_addr == dst.s_addr && ((p == 0) || (p == nat->nat_p))) { switch (p) { case IPPROTO_TCP : case IPPROTO_UDP : if (nat->nat_oport != dport) continue; if (nat->nat_inport != sport) continue; break; default : break; } ipn = nat->nat_ptr; if ((ipn != NULL) && (nat->nat_aps != NULL)) if (appr_match(fin, nat) != 0) continue; return nat; } } if (!nat_stats.ns_wilds || !(flags & FI_WILDP)) return NULL; if (!rw) { RWLOCK_EXIT(&ipf_nat); } hv = NAT_HASH_FN(dst.s_addr, srcip, ipf_nattable_sz); if (!rw) { WRITE_ENTER(&ipf_nat); } nat = nat_table[0][hv]; for (; nat; nat = nat->nat_hnext[0]) { nflags = nat->nat_flags; if (ifp && ifp != nat->nat_ifp) continue; if (!(nflags & FI_WILDP)) continue; if ((nat->nat_inip.s_addr != srcip) || (nat->nat_oip.s_addr != dst.s_addr)) continue; if (((nat->nat_inport == sport) || (nflags & FI_W_SPORT)) && ((nat->nat_oport == dport) || (nflags & FI_W_DPORT))) { nat_tabmove(fin, nat); break; } } if (!rw) { MUTEX_DOWNGRADE(&ipf_nat); } return nat; } /* * Lookup the NAT tables to search for a matching redirect */ nat_t *nat_lookupredir(np) natlookup_t *np; { nat_t *nat; fr_info_t fi; bzero((char *)&fi, sizeof(fi)); fi.fin_data[0] = ntohs(np->nl_inport); fi.fin_data[1] = ntohs(np->nl_outport); /* * 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(&fi, np->nl_flags, 0, np->nl_inip, np->nl_outip, 0))) { np->nl_realip = nat->nat_outip; np->nl_realport = nat->nat_outport; } return nat; } static int nat_match(fin, np, ip) fr_info_t *fin; ipnat_t *np; ip_t *ip; { frtuc_t *ft; if (ip->ip_v != 4) return 0; if (np->in_p && fin->fin_p != np->in_p) return 0; if (fin->fin_out) { if (!(np->in_redir & (NAT_MAP|NAT_MAPBLK))) return 0; if (((fin->fin_fi.fi_saddr & np->in_inmsk) != np->in_inip) ^ ((np->in_flags & IPN_NOTSRC) != 0)) return 0; if (((fin->fin_fi.fi_daddr & np->in_srcmsk) != np->in_srcip) ^ ((np->in_flags & IPN_NOTDST) != 0)) return 0; } else { if (!(np->in_redir & NAT_REDIRECT)) return 0; if (((fin->fin_fi.fi_saddr & np->in_srcmsk) != np->in_srcip) ^ ((np->in_flags & IPN_NOTSRC) != 0)) return 0; if (((fin->fin_fi.fi_daddr & np->in_outmsk) != np->in_outip) ^ ((np->in_flags & IPN_NOTDST) != 0)) return 0; } ft = &np->in_tuc; if (!(fin->fin_fl & FI_TCPUDP) || (fin->fin_fl & FI_SHORT) || (fin->fin_off != 0)) { if (ft->ftu_scmp || ft->ftu_dcmp) return 0; return 1; } return fr_tcpudpchk(ft, fin); } /* * Packets going out on the external interface go through this. * Here, the source address requires alteration, if anything. */ int ip_natout(ip, fin) ip_t *ip; fr_info_t *fin; { ipnat_t *np = NULL; u_32_t ipa; tcphdr_t *tcp = NULL; u_short sport = 0, dport = 0, *csump = NULL; int natadd = 1, i, icmpset = 1; u_int nflags = 0, hv, msk; struct ifnet *ifp; frentry_t *fr; void *sifp; u_32_t iph; nat_t *nat; if (nat_list == NULL || (fr_nat_lock)) return 0; if ((fr = fin->fin_fr) && !(fr->fr_flags & FR_DUP) && fr->fr_tif.fd_ifp && fr->fr_tif.fd_ifp != (void *)-1) { sifp = fin->fin_ifp; fin->fin_ifp = fr->fr_tif.fd_ifp; } else sifp = fin->fin_ifp; ifp = fin->fin_ifp; if ((fin->fin_off == 0) && !(fin->fin_fl & FI_SHORT)) { if (fin->fin_p == IPPROTO_TCP) nflags = IPN_TCP; else if (fin->fin_p == IPPROTO_UDP) nflags = IPN_UDP; if ((nflags & IPN_TCPUDP)) { tcp = (tcphdr_t *)fin->fin_dp; sport = tcp->th_sport; dport = tcp->th_dport; } } ipa = fin->fin_saddr; READ_ENTER(&ipf_nat); if ((fin->fin_p == IPPROTO_ICMP) && (nat = nat_icmp(ip, fin, &nflags, NAT_OUTBOUND))) icmpset = 1; else if ((fin->fin_fl & FI_FRAG) && (nat = ipfr_nat_knownfrag(ip, fin))) natadd = 0; else if ((nat = nat_outlookup(fin, nflags|FI_WILDP|FI_WILDA, (u_int)fin->fin_p, fin->fin_src, fin->fin_dst, 0))) { nflags = nat->nat_flags; if ((nflags & (FI_W_SPORT|FI_W_DPORT)) != 0) { if ((nflags & FI_W_SPORT) && (nat->nat_inport != sport)) nat->nat_inport = sport; if ((nflags & FI_W_DPORT) && (nat->nat_oport != dport)) nat->nat_oport = dport; if (nat->nat_outport == 0) nat->nat_outport = sport; nat->nat_flags &= ~(FI_W_DPORT|FI_W_SPORT); nflags = nat->nat_flags; nat_stats.ns_wilds--; } } else { RWLOCK_EXIT(&ipf_nat); msk = 0xffffffff; i = 32; 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). */ maskloop: iph = ipa & htonl(msk); hv = NAT_HASH_FN(iph, 0, ipf_natrules_sz); for (np = nat_rules[hv]; np; np = np->in_mnext) { if (np->in_ifp && (np->in_ifp != ifp)) continue; if ((np->in_flags & IPN_RF) && !(np->in_flags & nflags)) continue; if (np->in_flags & IPN_FILTER) { if (!nat_match(fin, np, ip)) continue; } else if ((ipa & np->in_inmsk) != np->in_inip) continue; if (*np->in_plabel && !appr_ok(ip, tcp, np)) continue; nat = nat_new(fin, ip, np, NULL, (u_int)nflags, NAT_OUTBOUND); if (nat != NULL) { np->in_hits++; break; } } if ((np == NULL) && (i > 0)) { do { i--; msk <<= 1; } while ((i >= 0) && ((nat_masks & (1 << i)) == 0)); if (i >= 0) goto maskloop; } MUTEX_DOWNGRADE(&ipf_nat); } /* * NOTE: ipf_nat must now only be held as a read lock */ if (nat) { np = nat->nat_ptr; if (natadd && (fin->fin_fl & FI_FRAG) && np) ipfr_nat_newfrag(ip, fin, nat); MUTEX_ENTER(&nat->nat_lock); if (fin->fin_p != IPPROTO_TCP) { if (np && np->in_age[1]) nat->nat_age = np->in_age[1]; else if (!icmpset && (fin->fin_p == IPPROTO_ICMP)) nat->nat_age = fr_defnaticmpage; else nat->nat_age = fr_defnatage; } nat->nat_bytes += ip->ip_len; nat->nat_pkts++; MUTEX_EXIT(&nat->nat_lock); /* * Fix up checksums, not by recalculating them, but * simply computing adjustments. */ if (nflags == IPN_ICMPERR) { u_32_t s1, s2, sumd; s1 = LONG_SUM(ntohl(fin->fin_saddr)); s2 = LONG_SUM(ntohl(nat->nat_outip.s_addr)); CALC_SUMD(s1, s2, sumd); fix_outcksum(fin, &ip->ip_sum, sumd); } #if (SOLARIS || defined(__sgi)) || !defined(_KERNEL) else { if (nat->nat_dir == NAT_OUTBOUND) fix_outcksum(fin, &ip->ip_sum, nat->nat_ipsumd); else fix_incksum(fin, &ip->ip_sum, nat->nat_ipsumd); } #endif /* * Only change the packet contents, not what is filtered upon. */ ip->ip_src = nat->nat_outip; if ((fin->fin_off == 0) && !(fin->fin_fl & FI_SHORT)) { if ((nat->nat_outport != 0) && (tcp != NULL)) { tcp->th_sport = nat->nat_outport; fin->fin_data[0] = ntohs(tcp->th_sport); } if (fin->fin_p == IPPROTO_TCP) { csump = &tcp->th_sum; MUTEX_ENTER(&nat->nat_lock); fr_tcp_age(&nat->nat_age, nat->nat_tcpstate, fin, 1, 0); if (nat->nat_age < fr_defnaticmpage) nat->nat_age = fr_defnaticmpage; #ifdef LARGE_NAT else if ((!np || !np->in_age[1]) && (nat->nat_age > fr_defnatage)) nat->nat_age = fr_defnatage; #endif /* * 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; /* * Do a MSS CLAMPING on a SYN packet, * only deal IPv4 for now. */ if (nat->nat_mssclamp && (tcp->th_flags & TH_SYN) != 0) nat_mssclamp(tcp, nat->nat_mssclamp, fin, csump); MUTEX_EXIT(&nat->nat_lock); } else if (fin->fin_p == IPPROTO_UDP) { udphdr_t *udp = (udphdr_t *)tcp; if (udp->uh_sum) csump = &udp->uh_sum; } if (csump) { if (nat->nat_dir == NAT_OUTBOUND) fix_outcksum(fin, csump, nat->nat_sumd[1]); else fix_incksum(fin, csump, nat->nat_sumd[1]); } } if (np && (np->in_apr != NULL) && (np->in_dport == 0 || (tcp != NULL && dport == np->in_dport))) { i = appr_check(ip, fin, nat); if (i == 0) i = 1; else if (i == -1) nat->nat_drop[1]++; } else i = 1; ATOMIC_INCL(nat_stats.ns_mapped[1]); RWLOCK_EXIT(&ipf_nat); /* READ */ fin->fin_ifp = sifp; return i; } RWLOCK_EXIT(&ipf_nat); /* READ/WRITE */ fin->fin_ifp = sifp; return 0; } /* * Packets coming in from the external interface go through this. * Here, the destination address requires alteration, if anything. */ int ip_natin(ip, fin) ip_t *ip; fr_info_t *fin; { struct in_addr src; struct in_addr in; ipnat_t *np; u_short sport = 0, dport = 0, *csump = NULL; u_int nflags = 0, natadd = 1, hv, msk; struct ifnet *ifp = fin->fin_ifp; tcphdr_t *tcp = NULL; int i, icmpset = 0; nat_t *nat; u_32_t iph; if ((nat_list == NULL) || (ip->ip_v != 4) || (fr_nat_lock)) return 0; if ((fin->fin_off == 0) && !(fin->fin_fl & FI_SHORT)) { if (fin->fin_p == IPPROTO_TCP) nflags = IPN_TCP; else if (fin->fin_p == IPPROTO_UDP) nflags = IPN_UDP; if ((nflags & IPN_TCPUDP)) { tcp = (tcphdr_t *)fin->fin_dp; sport = tcp->th_sport; dport = tcp->th_dport; } } in = fin->fin_dst; /* make sure the source address is to be redirected */ src = fin->fin_src; READ_ENTER(&ipf_nat); if ((fin->fin_p == IPPROTO_ICMP) && (nat = nat_icmp(ip, fin, &nflags, NAT_INBOUND))) icmpset = 1; else if ((fin->fin_fl & FI_FRAG) && (nat = ipfr_nat_knownfrag(ip, fin))) natadd = 0; else if ((nat = nat_inlookup(fin, nflags|FI_WILDP|FI_WILDA, (u_int)fin->fin_p, fin->fin_src, in, 0))) { nflags = nat->nat_flags; if ((nflags & (FI_W_SPORT|FI_W_DPORT)) != 0) { if ((nat->nat_oport != sport) && (nflags & FI_W_DPORT)) nat->nat_oport = sport; if ((nat->nat_outport != dport) && (nflags & FI_W_SPORT)) nat->nat_outport = dport; nat->nat_flags &= ~(FI_W_SPORT|FI_W_DPORT); nflags = nat->nat_flags; nat_stats.ns_wilds--; } } else { RWLOCK_EXIT(&ipf_nat); msk = 0xffffffff; i = 32; 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). */ maskloop: iph = in.s_addr & htonl(msk); hv = NAT_HASH_FN(iph, 0, ipf_rdrrules_sz); for (np = rdr_rules[hv]; np; np = np->in_rnext) { if ((np->in_ifp && (np->in_ifp != ifp)) || (np->in_p && (np->in_p != fin->fin_p)) || (np->in_flags && !(nflags & np->in_flags))) continue; if (np->in_flags & IPN_FILTER) { if (!nat_match(fin, np, ip)) continue; } else if ((in.s_addr & np->in_outmsk) != np->in_outip) continue; if ((!np->in_pmin || (np->in_flags & IPN_FILTER) || ((ntohs(np->in_pmax) >= ntohs(dport)) && (ntohs(dport) >= ntohs(np->in_pmin))))) if ((nat = nat_new(fin, ip, np, NULL, nflags, NAT_INBOUND))) { np->in_hits++; break; } } if ((np == NULL) && (i > 0)) { do { i--; msk <<= 1; } while ((i >= 0) && ((rdr_masks & (1 << i)) == 0)); if (i >= 0) goto maskloop; } MUTEX_DOWNGRADE(&ipf_nat); } /* * NOTE: ipf_nat must now only be held as a read lock */ if (nat) { np = nat->nat_ptr; fin->fin_fr = nat->nat_fr; if (natadd && (fin->fin_fl & FI_FRAG) && np) ipfr_nat_newfrag(ip, fin, nat); if (np && (np->in_apr != NULL) && (np->in_dport == 0 || (tcp != NULL && sport == np->in_dport))) { i = appr_check(ip, fin, nat); if (i == -1) { nat->nat_drop[0]++; RWLOCK_EXIT(&ipf_nat); return i; } } MUTEX_ENTER(&nat->nat_lock); if (fin->fin_p != IPPROTO_TCP) { if (np && np->in_age[0]) nat->nat_age = np->in_age[0]; else if (!icmpset && (fin->fin_p == IPPROTO_ICMP)) nat->nat_age = fr_defnaticmpage; else nat->nat_age = fr_defnatage; } nat->nat_bytes += ip->ip_len; nat->nat_pkts++; MUTEX_EXIT(&nat->nat_lock); /* * Fix up checksums, not by recalculating them, but * simply computing adjustments. */ if (nat->nat_dir == NAT_OUTBOUND) fix_incksum(fin, &ip->ip_sum, nat->nat_ipsumd); else fix_outcksum(fin, &ip->ip_sum, nat->nat_ipsumd); ip->ip_dst = nat->nat_inip; fin->fin_fi.fi_daddr = nat->nat_inip.s_addr; if ((fin->fin_off == 0) && !(fin->fin_fl & FI_SHORT)) { if ((nat->nat_inport != 0) && (tcp != NULL)) { tcp->th_dport = nat->nat_inport; fin->fin_data[1] = ntohs(tcp->th_dport); } if (fin->fin_p == IPPROTO_TCP) { csump = &tcp->th_sum; MUTEX_ENTER(&nat->nat_lock); fr_tcp_age(&nat->nat_age, nat->nat_tcpstate, fin, 0, 0); if (nat->nat_age < fr_defnaticmpage) nat->nat_age = fr_defnaticmpage; #ifdef LARGE_NAT else if ((!np || !np->in_age[0]) && (nat->nat_age > fr_defnatage)) nat->nat_age = fr_defnatage; #endif /* * 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; /* * Do a MSS CLAMPING on a SYN packet, * only deal IPv4 for now. */ if (nat->nat_mssclamp && (tcp->th_flags & TH_SYN) != 0) nat_mssclamp(tcp, nat->nat_mssclamp, fin, csump); MUTEX_EXIT(&nat->nat_lock); } else if (fin->fin_p == IPPROTO_UDP) { udphdr_t *udp = (udphdr_t *)tcp; if (udp->uh_sum) csump = &udp->uh_sum; } if (csump) { if (nat->nat_dir == NAT_OUTBOUND) fix_incksum(fin, csump, nat->nat_sumd[0]); else fix_outcksum(fin, csump, nat->nat_sumd[0]); } } ATOMIC_INCL(nat_stats.ns_mapped[0]); RWLOCK_EXIT(&ipf_nat); /* READ */ return 1; } RWLOCK_EXIT(&ipf_nat); /* READ/WRITE */ 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(); RWLOCK_EXIT(&ipf_nat); if (nat_table[0] != NULL) { KFREES(nat_table[0], sizeof(nat_t *) * ipf_nattable_sz); nat_table[0] = NULL; } if (nat_table[1] != NULL) { KFREES(nat_table[1], sizeof(nat_t *) * ipf_nattable_sz); nat_table[1] = NULL; } if (nat_rules != NULL) { KFREES(nat_rules, sizeof(ipnat_t *) * ipf_natrules_sz); nat_rules = NULL; } if (rdr_rules != NULL) { KFREES(rdr_rules, sizeof(ipnat_t *) * ipf_rdrrules_sz); rdr_rules = NULL; } if (maptable != NULL) { KFREES(maptable, sizeof(hostmap_t *) * ipf_hostmap_sz); maptable = NULL; } } /* * Slowly expire held state for NAT entries. Timeouts are set in * expectation of this being called twice per second. */ void ip_natexpire() { struct nat *nat, **natp; #if defined(_KERNEL) && !SOLARIS && !defined(__DragonFly__) int s; #endif SPL_NET(s); WRITE_ENTER(&ipf_nat); for (natp = &nat_instances; (nat = *natp); ) { 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); nat_stats.ns_expire++; } RWLOCK_EXIT(&ipf_nat); SPL_X(s); } /* */ void ip_natsync(ifp) void *ifp; { ipnat_t *n; nat_t *nat; u_32_t sum1, sum2, sumd; struct in_addr in; ipnat_t *np; void *ifp2; #if defined(_KERNEL) && !SOLARIS && !defined(__DragonFly__) int s; #endif /* * Change IP addresses for NAT sessions for any protocol except TCP * since it will break the TCP connection anyway. */ SPL_NET(s); WRITE_ENTER(&ipf_nat); for (nat = nat_instances; nat; nat = nat->nat_next) if (((ifp == NULL) || (ifp == nat->nat_ifp)) && !(nat->nat_flags & IPN_TCP) && (np = nat->nat_ptr) && (np->in_outmsk == 0xffffffff) && !np->in_nip) { ifp2 = nat->nat_ifp; /* * Change the map-to address to be the same as the * new one. */ sum1 = nat->nat_outip.s_addr; if (fr_ifpaddr(4, ifp2, &in) != -1) nat->nat_outip = in; sum2 = nat->nat_outip.s_addr; if (sum1 == sum2) continue; /* * Readjust the checksum adjustment to take into * account the new IP#. */ CALC_SUMD(sum1, sum2, sumd); /* XXX - dont change for TCP when solaris does * hardware checksumming. */ sumd += nat->nat_sumd[0]; nat->nat_sumd[0] = (sumd & 0xffff) + (sumd >> 16); nat->nat_sumd[1] = nat->nat_sumd[0]; } for (n = nat_list; (n != NULL); n = n->in_next) if (n->in_ifp == ifp) { n->in_ifp = (void *)GETUNIT(n->in_ifname, 4); if (!n->in_ifp) n->in_ifp = (void *)-1; } RWLOCK_EXIT(&ipf_nat); SPL_X(s); } #ifdef IPFILTER_LOG void nat_log(nat, type) struct nat *nat; u_int type; { # ifndef LARGE_NAT struct ipnat *np; int rulen; # endif struct natlog natl; void *items[1]; size_t sizes[1]; int 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_p = nat->nat_p; natl.nl_type = type; natl.nl_rule = -1; #ifndef LARGE_NAT if (nat->nat_ptr != NULL) { for (rulen = 0, np = nat_list; np; np = np->in_next, rulen++) if (np == nat->nat_ptr) { natl.nl_rule = rulen; break; } } #endif items[0] = &natl; sizes[0] = sizeof(natl); types[0] = 0; (void) ipllog(IPL_LOGNAT, NULL, items, sizes, types, 1); } #endif #if defined(__OpenBSD__) void nat_ifdetach(ifp) void *ifp; { frsync(); return; } #endif /* * Check for MSS option and clamp it if necessary. */ static void nat_mssclamp(tcp, maxmss, fin, csump) tcphdr_t *tcp; u_32_t maxmss; fr_info_t *fin; u_short *csump; { u_char *cp, *ep, opt; int hlen, advance; u_32_t mss, sumd; u_short v; hlen = tcp->th_off << 2; if (hlen > sizeof(*tcp)) { cp = (u_char *)tcp + sizeof(*tcp); ep = (u_char *)tcp + hlen; while (cp < ep) { opt = cp[0]; if (opt == TCPOPT_EOL) break; else if (opt == TCPOPT_NOP) { cp++; continue; } if (&cp[1] >= ep) break; advance = cp[1]; if (&cp[advance] > ep) break; switch (opt) { case TCPOPT_MAXSEG: if (advance != 4) break; bcopy(&cp[2], &v, sizeof(v)); mss = ntohs(v); if (mss > maxmss) { v = htons(maxmss); bcopy(&v, &cp[2], sizeof(v)); CALC_SUMD(mss, maxmss, sumd); fix_outcksum(fin, csump, sumd); } break; default: /* ignore unknown options */ break; } cp += advance; } } }