sys/contrib/ipfilter/netinet/ip_rcmd_pxy.c

   1 /*      $FreeBSD$       */
   2
   3 /*
   4  * Copyright (C) 1998-2003 by Darren Reed
   5  *
   6  * See the IPFILTER.LICENCE file for details on licencing.
   7  *
   8  * $Id: ip_rcmd_pxy.c,v 1.41.2.7 2006/07/14 06:12:18 darrenr Exp $
   9  *
  10  * Simple RCMD transparent proxy for in-kernel use.  For use with the NAT
  11  * code.
  12  * $FreeBSD$
  13  */
  14
  15 #define IPF_RCMD_PROXY
  16
  17
  18 int ippr_rcmd_init __P((void));
  19 void ippr_rcmd_fini __P((void));
  20 int ippr_rcmd_new __P((fr_info_t *, ap_session_t *, nat_t *));
  21 int ippr_rcmd_out __P((fr_info_t *, ap_session_t *, nat_t *));
  22 int ippr_rcmd_in __P((fr_info_t *, ap_session_t *, nat_t *));
  23 u_short ipf_rcmd_atoi __P((char *));
  24 int ippr_rcmd_portmsg __P((fr_info_t *, ap_session_t *, nat_t *));
  25
  26 static  frentry_t       rcmdfr;
  27
  28 int     rcmd_proxy_init = 0;
  29
  30
  31 /*
  32  * RCMD application proxy initialization.
  33  */
  34 int ippr_rcmd_init()
  35 {
  36         bzero((char *)&rcmdfr, sizeof(rcmdfr));
  37         rcmdfr.fr_ref = 1;
  38         rcmdfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
  39         MUTEX_INIT(&rcmdfr.fr_lock, "RCMD proxy rule lock");
  40         rcmd_proxy_init = 1;
  41
  42         return 0;
  43 }
  44
  45
  46 void ippr_rcmd_fini()
  47 {
  48         if (rcmd_proxy_init == 1) {
  49                 MUTEX_DESTROY(&rcmdfr.fr_lock);
  50                 rcmd_proxy_init = 0;
  51         }
  52 }
  53
  54
  55 /*
  56  * Setup for a new RCMD proxy.
  57  */
  58 int ippr_rcmd_new(fin, aps, nat)
  59 fr_info_t *fin;
  60 ap_session_t *aps;
  61 nat_t *nat;
  62 {
  63         tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
  64
  65         fin = fin;      /* LINT */
  66         nat = nat;      /* LINT */
  67
  68         aps->aps_psiz = sizeof(u_32_t);
  69         KMALLOCS(aps->aps_data, u_32_t *, sizeof(u_32_t));
  70         if (aps->aps_data == NULL) {
  71 #ifdef IP_RCMD_PROXY_DEBUG
  72                 printf("ippr_rcmd_new:KMALLOCS(%d) failed\n", sizeof(u_32_t));
  73 #endif
  74                 return -1;
  75         }
  76         *(u_32_t *)aps->aps_data = 0;
  77         aps->aps_sport = tcp->th_sport;
  78         aps->aps_dport = tcp->th_dport;
  79         return 0;
  80 }
  81
  82
  83 /*
  84  * ipf_rcmd_atoi - implement a simple version of atoi
  85  */
  86 u_short ipf_rcmd_atoi(ptr)
  87 char *ptr;
  88 {
  89         register char *s = ptr, c;
  90         register u_short i = 0;
  91
  92         while (((c = *s++) != '\0') && ISDIGIT(c)) {
  93                 i *= 10;
  94                 i += c - '0';
  95         }
  96         return i;
  97 }
  98
  99
 100 int ippr_rcmd_portmsg(fin, aps, nat)
 101 fr_info_t *fin;
 102 ap_session_t *aps;
 103 nat_t *nat;
 104 {
 105         tcphdr_t *tcp, tcph, *tcp2 = &tcph;
 106         struct in_addr swip, swip2;
 107         int off, dlen, nflags;
 108         char portbuf[8], *s;
 109         fr_info_t fi;
 110         u_short sp;
 111         nat_t *nat2;
 112         ip_t *ip;
 113         mb_t *m;
 114
 115         tcp = (tcphdr_t *)fin->fin_dp;
 116
 117         if (tcp->th_flags & TH_SYN) {
 118                 *(u_32_t *)aps->aps_data = htonl(ntohl(tcp->th_seq) + 1);
 119                 return 0;
 120         }
 121
 122         if ((*(u_32_t *)aps->aps_data != 0) &&
 123             (tcp->th_seq != *(u_32_t *)aps->aps_data))
 124                 return 0;
 125
 126         m = fin->fin_m;
 127         ip = fin->fin_ip;
 128         off = (char *)tcp - (char *)ip + (TCP_OFF(tcp) << 2) + fin->fin_ipoff;
 129
 130 #ifdef __sgi
 131         dlen = fin->fin_plen - off;
 132 #else
 133         dlen = MSGDSIZE(m) - off;
 134 #endif
 135         if (dlen <= 0)
 136                 return 0;
 137
 138         bzero(portbuf, sizeof(portbuf));
 139         COPYDATA(m, off, MIN(sizeof(portbuf), dlen), portbuf);
 140
 141         portbuf[sizeof(portbuf) - 1] = '\0';
 142         s = portbuf;
 143         sp = ipf_rcmd_atoi(s);
 144         if (sp == 0) {
 145 #ifdef IP_RCMD_PROXY_DEBUG
 146                 printf("ippr_rcmd_portmsg:sp == 0 dlen %d [%s]\n",
 147                        dlen, portbuf);
 148 #endif
 149                 return 0;
 150         }
 151
 152         /*
 153          * Add skeleton NAT entry for connection which will come back the
 154          * other way.
 155          */
 156         bcopy((char *)fin, (char *)&fi, sizeof(fi));
 157         fi.fin_state = NULL;
 158         fi.fin_nat = NULL;
 159         fi.fin_flx |= FI_IGNORE;
 160         fi.fin_data[0] = sp;
 161         fi.fin_data[1] = 0;
 162         if (nat->nat_dir == NAT_OUTBOUND)
 163                 nat2 = nat_outlookup(&fi, NAT_SEARCH|IPN_TCP, nat->nat_p,
 164                                      nat->nat_inip, nat->nat_oip);
 165         else
 166                 nat2 = nat_inlookup(&fi, NAT_SEARCH|IPN_TCP, nat->nat_p,
 167                                     nat->nat_inip, nat->nat_oip);
 168         if (nat2 == NULL) {
 169                 int slen;
 170
 171                 slen = ip->ip_len;
 172                 ip->ip_len = fin->fin_hlen + sizeof(*tcp);
 173                 bzero((char *)tcp2, sizeof(*tcp2));
 174                 tcp2->th_win = htons(8192);
 175                 tcp2->th_sport = htons(sp);
 176                 tcp2->th_dport = 0; /* XXX - don't specify remote port */
 177                 TCP_OFF_A(tcp2, 5);
 178                 tcp2->th_flags = TH_SYN;
 179                 fi.fin_dp = (char *)tcp2;
 180                 fi.fin_fr = &rcmdfr;
 181                 fi.fin_dlen = sizeof(*tcp2);
 182                 fi.fin_plen = fi.fin_hlen + sizeof(*tcp2);
 183                 fi.fin_flx &= FI_LOWTTL|FI_FRAG|FI_TCPUDP|FI_OPTIONS|FI_IGNORE;
 184                 nflags = NAT_SLAVE|IPN_TCP|SI_W_DPORT;
 185
 186                 swip = ip->ip_src;
 187                 swip2 = ip->ip_dst;
 188
 189                 if (nat->nat_dir == NAT_OUTBOUND) {
 190                         fi.fin_fi.fi_saddr = nat->nat_inip.s_addr;
 191                         ip->ip_src = nat->nat_inip;
 192                 } else {
 193                         fi.fin_fi.fi_saddr = nat->nat_oip.s_addr;
 194                         ip->ip_src = nat->nat_oip;
 195                         nflags |= NAT_NOTRULEPORT;
 196                 }
 197
 198                 nat2 = nat_new(&fi, nat->nat_ptr, NULL, nflags, nat->nat_dir);
 199
 200                 if (nat2 != NULL) {
 201                         (void) nat_proto(&fi, nat2, IPN_TCP);
 202                         nat_update(&fi, nat2, nat2->nat_ptr);
 203                         fi.fin_ifp = NULL;
 204                         if (nat->nat_dir == NAT_INBOUND) {
 205                                 fi.fin_fi.fi_daddr = nat->nat_inip.s_addr;
 206                                 ip->ip_dst = nat->nat_inip;
 207                         }
 208                         (void) fr_addstate(&fi, NULL, SI_W_DPORT);
 209                         if (fi.fin_state != NULL)
 210                                 fr_statederef((ipstate_t **)&fi.fin_state);
 211                 }
 212                 ip->ip_len = slen;
 213                 ip->ip_src = swip;
 214                 ip->ip_dst = swip2;
 215         }
 216         return 0;
 217 }
 218
 219
 220 int ippr_rcmd_out(fin, aps, nat)
 221 fr_info_t *fin;
 222 ap_session_t *aps;
 223 nat_t *nat;
 224 {
 225         if (nat->nat_dir == NAT_OUTBOUND)
 226                 return ippr_rcmd_portmsg(fin, aps, nat);
 227         return 0;
 228 }
 229
 230
 231 int ippr_rcmd_in(fin, aps, nat)
 232 fr_info_t *fin;
 233 ap_session_t *aps;
 234 nat_t *nat;
 235 {
 236         if (nat->nat_dir == NAT_INBOUND)
 237                 return ippr_rcmd_portmsg(fin, aps, nat);
 238         return 0;
 239 }