sys/contrib/ipfilter/netinet/ip_rcmd_pxy.c

   1 /*      $FreeBSD$       */
   2
   3 /*
   4  * Copyright (C) 2012 by Darren Reed.
   5  *
   6  * See the IPFILTER.LICENCE file for details on licencing.
   7  *
   8  * $Id$
   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 typedef struct rcmdinfo {
  18         u_32_t  rcmd_port;      /* Port number seen */
  19         u_32_t  rcmd_portseq;   /* Sequence number where port is first seen */
  20         ipnat_t *rcmd_rule;     /* Template rule for back connection */
  21 } rcmdinfo_t;
  22
  23 void ipf_p_rcmd_main_load __P((void));
  24 void ipf_p_rcmd_main_unload __P((void));
  25
  26 int ipf_p_rcmd_init __P((void));
  27 void ipf_p_rcmd_fini __P((void));
  28 void ipf_p_rcmd_del __P((ipf_main_softc_t *, ap_session_t *));
  29 int ipf_p_rcmd_new __P((void *, fr_info_t *, ap_session_t *, nat_t *));
  30 int ipf_p_rcmd_out __P((void *, fr_info_t *, ap_session_t *, nat_t *));
  31 int ipf_p_rcmd_in __P((void *, fr_info_t *, ap_session_t *, nat_t *));
  32 u_short ipf_rcmd_atoi __P((char *));
  33 int ipf_p_rcmd_portmsg __P((fr_info_t *, ap_session_t *, nat_t *));
  34
  35 static  frentry_t       rcmdfr;
  36
  37 static  int             rcmd_proxy_init = 0;
  38
  39
  40 /*
  41  * RCMD application proxy initialization.
  42  */
  43 void
  44 ipf_p_rcmd_main_load()
  45 {
  46         bzero((char *)&rcmdfr, sizeof(rcmdfr));
  47         rcmdfr.fr_ref = 1;
  48         rcmdfr.fr_flags = FR_INQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
  49         MUTEX_INIT(&rcmdfr.fr_lock, "RCMD proxy rule lock");
  50         rcmd_proxy_init = 1;
  51 }
  52
  53
  54 void
  55 ipf_p_rcmd_main_unload()
  56 {
  57         if (rcmd_proxy_init == 1) {
  58                 MUTEX_DESTROY(&rcmdfr.fr_lock);
  59                 rcmd_proxy_init = 0;
  60         }
  61 }
  62
  63
  64 /*
  65  * Setup for a new RCMD proxy.
  66  */
  67 int
  68 ipf_p_rcmd_new(arg, fin, aps, nat)
  69         void *arg;
  70         fr_info_t *fin;
  71         ap_session_t *aps;
  72         nat_t *nat;
  73 {
  74         tcphdr_t *tcp = (tcphdr_t *)fin->fin_dp;
  75         rcmdinfo_t *rc;
  76         ipnat_t *ipn;
  77         ipnat_t *np;
  78         int size;
  79
  80         fin = fin;      /* LINT */
  81
  82         np = nat->nat_ptr;
  83         size = np->in_size;
  84         KMALLOC(rc, rcmdinfo_t *);
  85         if (rc == NULL) {
  86 #ifdef IP_RCMD_PROXY_DEBUG
  87                 printf("ipf_p_rcmd_new:KMALLOCS(%d) failed\n", sizeof(*rc));
  88 #endif
  89                 return -1;
  90         }
  91         aps->aps_sport = tcp->th_sport;
  92         aps->aps_dport = tcp->th_dport;
  93
  94         ipn = ipf_proxy_rule_rev(nat);
  95         if (ipn == NULL) {
  96                 KFREE(rc);
  97                 return -1;
  98         }
  99
 100         aps->aps_data = rc;
 101         aps->aps_psiz = sizeof(*rc);
 102         bzero((char *)rc, sizeof(*rc));
 103
 104         rc->rcmd_rule = ipn;
 105
 106         return 0;
 107 }
 108
 109
 110 void
 111 ipf_p_rcmd_del(softc, aps)
 112         ipf_main_softc_t *softc;
 113         ap_session_t *aps;
 114 {
 115         rcmdinfo_t *rci;
 116
 117         rci = aps->aps_data;
 118         if (rci != NULL) {
 119                 rci->rcmd_rule->in_flags |= IPN_DELETE;
 120                 ipf_nat_rule_deref(softc, &rci->rcmd_rule);
 121         }
 122 }
 123
 124
 125 /*
 126  * ipf_rcmd_atoi - implement a simple version of atoi
 127  */
 128 u_short
 129 ipf_rcmd_atoi(ptr)
 130         char *ptr;
 131 {
 132         register char *s = ptr, c;
 133         register u_short i = 0;
 134
 135         while (((c = *s++) != '\0') && ISDIGIT(c)) {
 136                 i *= 10;
 137                 i += c - '0';
 138         }
 139         return i;
 140 }
 141
 142
 143 int
 144 ipf_p_rcmd_portmsg(fin, aps, nat)
 145         fr_info_t *fin;
 146         ap_session_t *aps;
 147         nat_t *nat;
 148 {
 149         tcphdr_t *tcp, tcph, *tcp2 = &tcph;
 150         int off, dlen, nflags, direction;
 151         ipf_main_softc_t *softc;
 152         ipf_nat_softc_t *softn;
 153         char portbuf[8], *s;
 154         rcmdinfo_t *rc;
 155         fr_info_t fi;
 156         u_short sp;
 157         nat_t *nat2;
 158 #ifdef USE_INET6
 159         ip6_t *ip6;
 160 #endif
 161         int tcpsz;
 162         int slen = 0; /* silence gcc */
 163         ip_t *ip;
 164         mb_t *m;
 165
 166         tcp = (tcphdr_t *)fin->fin_dp;
 167
 168         m = fin->fin_m;
 169         ip = fin->fin_ip;
 170         tcpsz = TCP_OFF(tcp) << 2;
 171 #ifdef USE_INET6
 172         ip6 = (ip6_t *)fin->fin_ip;
 173 #endif
 174         softc = fin->fin_main_soft;
 175         softn = softc->ipf_nat_soft;
 176         off = (char *)tcp - (char *)ip + tcpsz + fin->fin_ipoff;
 177
 178         dlen = fin->fin_dlen - tcpsz;
 179         if (dlen <= 0)
 180                 return 0;
 181
 182         rc = (rcmdinfo_t *)aps->aps_data;
 183         if ((rc->rcmd_portseq != 0) &&
 184             (tcp->th_seq != rc->rcmd_portseq))
 185                 return 0;
 186
 187         bzero(portbuf, sizeof(portbuf));
 188         COPYDATA(m, off, MIN(sizeof(portbuf), dlen), portbuf);
 189
 190         portbuf[sizeof(portbuf) - 1] = '\0';
 191         s = portbuf;
 192         sp = ipf_rcmd_atoi(s);
 193         if (sp == 0) {
 194 #ifdef IP_RCMD_PROXY_DEBUG
 195                 printf("ipf_p_rcmd_portmsg:sp == 0 dlen %d [%s]\n",
 196                        dlen, portbuf);
 197 #endif
 198                 return 0;
 199         }
 200
 201         if (rc->rcmd_port != 0 && sp != rc->rcmd_port) {
 202 #ifdef IP_RCMD_PROXY_DEBUG
 203                 printf("ipf_p_rcmd_portmsg:sp(%d) != rcmd_port(%d)\n",
 204                        sp, rc->rcmd_port);
 205 #endif
 206                 return 0;
 207         }
 208
 209         rc->rcmd_port = sp;
 210         rc->rcmd_portseq = tcp->th_seq;
 211
 212         /*
 213          * Initialise the packet info structure so we can search the NAT
 214          * table to see if there already is soemthing present that matches
 215          * up with what we want to add.
 216          */
 217         bcopy((char *)fin, (char *)&fi, sizeof(fi));
 218         fi.fin_flx |= FI_IGNORE;
 219         fi.fin_data[0] = 0;
 220         fi.fin_data[1] = sp;
 221         fi.fin_src6 = nat->nat_ndst6;
 222         fi.fin_dst6 = nat->nat_nsrc6;
 223
 224         if (nat->nat_v[0] == 6) {
 225 #ifdef USE_INET6
 226                 if (nat->nat_dir == NAT_OUTBOUND) {
 227                         nat2 = ipf_nat6_outlookup(&fi, NAT_SEARCH|IPN_TCP,
 228                                                   nat->nat_pr[1],
 229                                                   &nat->nat_osrc6.in6,
 230                                                   &nat->nat_odst6.in6);
 231                 } else {
 232                         nat2 = ipf_nat6_inlookup(&fi, NAT_SEARCH|IPN_TCP,
 233                                                  nat->nat_pr[0],
 234                                                  &nat->nat_osrc6.in6,
 235                                                  &nat->nat_odst6.in6);
 236                 }
 237 #else
 238                 nat2 = (void *)-1;
 239 #endif
 240         } else {
 241                 if (nat->nat_dir == NAT_OUTBOUND) {
 242                         nat2 = ipf_nat_outlookup(&fi, NAT_SEARCH|IPN_TCP,
 243                                                  nat->nat_pr[1],
 244                                                  nat->nat_osrcip,
 245                                                  nat->nat_odstip);
 246                 } else {
 247                         nat2 = ipf_nat_inlookup(&fi, NAT_SEARCH|IPN_TCP,
 248                                                 nat->nat_pr[0],
 249                                                 nat->nat_osrcip,
 250                                                 nat->nat_odstip);
 251                 }
 252         }
 253         if (nat2 != NULL)
 254                 return APR_ERR(1);
 255
 256         /*
 257          * Add skeleton NAT entry for connection which will come
 258          * back the other way.
 259          */
 260
 261         if (nat->nat_v[0] == 6) {
 262 #ifdef USE_INET6
 263                 slen = ip6->ip6_plen;
 264                 ip6->ip6_plen = htons(sizeof(*tcp));
 265 #endif
 266         } else {
 267                 slen = ip->ip_len;
 268                 ip->ip_len = htons(fin->fin_hlen + sizeof(*tcp));
 269         }
 270
 271         /*
 272          * Fill out the fake TCP header with a few fields that ipfilter
 273          * considers to be important.
 274          */
 275         bzero((char *)tcp2, sizeof(*tcp2));
 276         tcp2->th_win = htons(8192);
 277         TCP_OFF_A(tcp2, 5);
 278         tcp2->th_flags = TH_SYN;
 279
 280         fi.fin_dp = (char *)tcp2;
 281         fi.fin_fr = &rcmdfr;
 282         fi.fin_dlen = sizeof(*tcp2);
 283         fi.fin_plen = fi.fin_hlen + sizeof(*tcp2);
 284         fi.fin_flx &= FI_LOWTTL|FI_FRAG|FI_TCPUDP|FI_OPTIONS|FI_IGNORE;
 285
 286         if (nat->nat_dir == NAT_OUTBOUND) {
 287                 fi.fin_out = 0;
 288                 direction = NAT_INBOUND;
 289         } else {
 290                 fi.fin_out = 1;
 291                 direction = NAT_OUTBOUND;
 292         }
 293         nflags = SI_W_SPORT|NAT_SLAVE|IPN_TCP;
 294
 295         MUTEX_ENTER(&softn->ipf_nat_new);
 296         if (fin->fin_v == 4)
 297                 nat2 = ipf_nat_add(&fi, rc->rcmd_rule, NULL, nflags,
 298                                    direction);
 299 #ifdef USE_INET6
 300         else
 301                 nat2 = ipf_nat6_add(&fi, rc->rcmd_rule, NULL, nflags,
 302                                     direction);
 303 #endif
 304         MUTEX_EXIT(&softn->ipf_nat_new);
 305
 306         if (nat2 != NULL) {
 307                 (void) ipf_nat_proto(&fi, nat2, IPN_TCP);
 308                 MUTEX_ENTER(&nat2->nat_lock);
 309                 ipf_nat_update(&fi, nat2);
 310                 MUTEX_EXIT(&nat2->nat_lock);
 311                 fi.fin_ifp = NULL;
 312                 if (nat2->nat_dir == NAT_INBOUND)
 313                         fi.fin_dst6 = nat->nat_osrc6;
 314                 (void) ipf_state_add(softc, &fi, NULL, SI_W_SPORT);
 315         }
 316         if (nat->nat_v[0] == 6) {
 317 #ifdef USE_INET6
 318                 ip6->ip6_plen = slen;
 319 #endif
 320         } else {
 321                 ip->ip_len = slen;
 322         }
 323         if (nat2 == NULL)
 324                 return APR_ERR(1);
 325         return 0;
 326 }
 327
 328
 329 int
 330 ipf_p_rcmd_out(arg, fin, aps, nat)
 331         void *arg;
 332         fr_info_t *fin;
 333         ap_session_t *aps;
 334         nat_t *nat;
 335 {
 336         if (nat->nat_dir == NAT_OUTBOUND)
 337                 return ipf_p_rcmd_portmsg(fin, aps, nat);
 338         return 0;
 339 }
 340
 341
 342 int
 343 ipf_p_rcmd_in(arg, fin, aps, nat)
 344         void *arg;
 345         fr_info_t *fin;
 346         ap_session_t *aps;
 347         nat_t *nat;
 348 {
 349         if (nat->nat_dir == NAT_INBOUND)
 350                 return ipf_p_rcmd_portmsg(fin, aps, nat);
 351         return 0;
 352 }