ip_ipsec_pxy.c

   1 /*      $NetBSD$        */
   2
   3 /*
   4  * Copyright (C) 2001-2003 by Darren Reed
   5  *
   6  * See the IPFILTER.LICENCE file for details on licencing.
   7  *
   8  * Simple ISAKMP transparent proxy for in-kernel use.  For use with the NAT
   9  * code.
  10  *
  11  * Id: ip_ipsec_pxy.c,v 2.20.2.6 2005/03/28 10:47:53 darrenr Exp
  12  *
  13  */
  14 #define IPF_IPSEC_PROXY
  15
  16
  17 int ippr_ipsec_init __P((void));
  18 void ippr_ipsec_fini __P((void));
  19 int ippr_ipsec_new __P((fr_info_t *, ap_session_t *, nat_t *));
  20 void ippr_ipsec_del __P((ap_session_t *));
  21 int ippr_ipsec_inout __P((fr_info_t *, ap_session_t *, nat_t *));
  22 int ippr_ipsec_match __P((fr_info_t *, ap_session_t *, nat_t *));
  23
  24 static  frentry_t       ipsecfr;
  25 static  ipftq_t         *ipsecnattqe;
  26 static  ipftq_t         *ipsecstatetqe;
  27 static  char    ipsec_buffer[1500];
  28
  29 int     ipsec_proxy_init = 0;
  30 int     ipsec_proxy_ttl = 60;
  31
  32 /*
  33  * IPSec application proxy initialization.
  34  */
  35 int ippr_ipsec_init()
  36 {
  37         bzero((char *)&ipsecfr, sizeof(ipsecfr));
  38         ipsecfr.fr_ref = 1;
  39         ipsecfr.fr_flags = FR_OUTQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
  40         MUTEX_INIT(&ipsecfr.fr_lock, "IPsec proxy rule lock");
  41         ipsec_proxy_init = 1;
  42
  43         ipsecnattqe = fr_addtimeoutqueue(&nat_utqe, ipsec_proxy_ttl);
  44         if (ipsecnattqe == NULL)
  45                 return -1;
  46         ipsecstatetqe = fr_addtimeoutqueue(&ips_utqe, ipsec_proxy_ttl);
  47         if (ipsecstatetqe == NULL) {
  48                 if (fr_deletetimeoutqueue(ipsecnattqe) == 0)
  49                         fr_freetimeoutqueue(ipsecnattqe);
  50                 ipsecnattqe = NULL;
  51                 return -1;
  52         }
  53
  54         ipsecnattqe->ifq_flags |= IFQF_PROXY;
  55         ipsecstatetqe->ifq_flags |= IFQF_PROXY;
  56
  57         ipsecfr.fr_age[0] = ipsec_proxy_ttl;
  58         ipsecfr.fr_age[1] = ipsec_proxy_ttl;
  59         return 0;
  60 }
  61
  62
  63 void ippr_ipsec_fini()
  64 {
  65         if (ipsecnattqe != NULL) {
  66                 if (fr_deletetimeoutqueue(ipsecnattqe) == 0)
  67                         fr_freetimeoutqueue(ipsecnattqe);
  68         }
  69         ipsecnattqe = NULL;
  70         if (ipsecstatetqe != NULL) {
  71                 if (fr_deletetimeoutqueue(ipsecstatetqe) == 0)
  72                         fr_freetimeoutqueue(ipsecstatetqe);
  73         }
  74         ipsecstatetqe = NULL;
  75
  76         if (ipsec_proxy_init == 1) {
  77                 MUTEX_DESTROY(&ipsecfr.fr_lock);
  78                 ipsec_proxy_init = 0;
  79         }
  80 }
  81
  82
  83 /*
  84  * Setup for a new IPSEC proxy.
  85  */
  86 int ippr_ipsec_new(fin, aps, nat)
  87 fr_info_t *fin;
  88 ap_session_t *aps;
  89 nat_t *nat;
  90 {
  91         ipsec_pxy_t *ipsec;
  92         fr_info_t fi;
  93         ipnat_t *ipn;
  94         char *ptr;
  95         int p, off, dlen, ttl;
  96         mb_t *m;
  97         ip_t *ip;
  98
  99         bzero(ipsec_buffer, sizeof(ipsec_buffer));
 100         off = fin->fin_hlen + sizeof(udphdr_t);
 101         ip = fin->fin_ip;
 102         m = fin->fin_m;
 103
 104         dlen = M_LEN(m) - off;
 105         if (dlen < 16)
 106                 return -1;
 107         COPYDATA(m, off, MIN(sizeof(ipsec_buffer), dlen), ipsec_buffer);
 108
 109         if (nat_outlookup(fin, 0, IPPROTO_ESP, nat->nat_inip,
 110                           ip->ip_dst) != NULL)
 111                 return -1;
 112
 113         aps->aps_psiz = sizeof(*ipsec);
 114         KMALLOCS(aps->aps_data, ipsec_pxy_t *, sizeof(*ipsec));
 115         if (aps->aps_data == NULL)
 116                 return -1;
 117
 118         ipsec = aps->aps_data;
 119         bzero((char *)ipsec, sizeof(*ipsec));
 120
 121         /*
 122          * Create NAT rule against which the tunnel/transport mapping is
 123          * created.  This is required because the current NAT rule does not
 124          * describe ESP but UDP instead.
 125          */
 126         ipn = &ipsec->ipsc_rule;
 127         ttl = IPF_TTLVAL(ipsecnattqe->ifq_ttl);
 128         ipn->in_tqehead[0] = fr_addtimeoutqueue(&nat_utqe, ttl);
 129         ipn->in_tqehead[1] = fr_addtimeoutqueue(&nat_utqe, ttl);
 130         ipn->in_ifps[0] = fin->fin_ifp;
 131         ipn->in_apr = NULL;
 132         ipn->in_use = 1;
 133         ipn->in_hits = 1;
 134         ipn->in_nip = ntohl(nat->nat_outip.s_addr);
 135         ipn->in_ippip = 1;
 136         ipn->in_inip = nat->nat_inip.s_addr;
 137         ipn->in_inmsk = 0xffffffff;
 138         ipn->in_outip = fin->fin_saddr;
 139         ipn->in_outmsk = nat->nat_outip.s_addr;
 140         ipn->in_srcip = fin->fin_saddr;
 141         ipn->in_srcmsk = 0xffffffff;
 142         ipn->in_redir = NAT_MAP;
 143         bcopy(nat->nat_ptr->in_ifnames[0], ipn->in_ifnames[0],
 144               sizeof(ipn->in_ifnames[0]));
 145         ipn->in_p = IPPROTO_ESP;
 146
 147         bcopy((char *)fin, (char *)&fi, sizeof(fi));
 148         fi.fin_state = NULL;
 149         fi.fin_nat = NULL;
 150         fi.fin_fi.fi_p = IPPROTO_ESP;
 151         fi.fin_fr = &ipsecfr;
 152         fi.fin_data[0] = 0;
 153         fi.fin_data[1] = 0;
 154         p = ip->ip_p;
 155         ip->ip_p = IPPROTO_ESP;
 156         fi.fin_flx &= ~(FI_TCPUDP|FI_STATE|FI_FRAG);
 157         fi.fin_flx |= FI_IGNORE;
 158
 159         ptr = ipsec_buffer;
 160         bcopy(ptr, (char *)ipsec->ipsc_icookie, sizeof(ipsec_cookie_t));
 161         ptr += sizeof(ipsec_cookie_t);
 162         bcopy(ptr, (char *)ipsec->ipsc_rcookie, sizeof(ipsec_cookie_t));
 163         /*
 164          * The responder cookie should only be non-zero if the initiator
 165          * cookie is non-zero.  Therefore, it is safe to assume(!) that the
 166          * cookies are both set after copying if the responder is non-zero.
 167          */
 168         if ((ipsec->ipsc_rcookie[0]|ipsec->ipsc_rcookie[1]) != 0)
 169                 ipsec->ipsc_rckset = 1;
 170
 171         ipsec->ipsc_nat = nat_new(&fi, ipn, &ipsec->ipsc_nat,
 172                                   NAT_SLAVE|SI_WILDP, NAT_OUTBOUND);
 173         if (ipsec->ipsc_nat != NULL) {
 174                 (void) nat_proto(&fi, ipsec->ipsc_nat, 0);
 175                 nat_update(&fi, ipsec->ipsc_nat, ipn);
 176
 177                 fi.fin_data[0] = 0;
 178                 fi.fin_data[1] = 0;
 179                 ipsec->ipsc_state = fr_addstate(&fi, &ipsec->ipsc_state,
 180                                                 SI_WILDP);
 181                 if (fi.fin_state != NULL)
 182                         fr_statederef(&fi, (ipstate_t **)&fi.fin_state);
 183         }
 184         ip->ip_p = p & 0xff;
 185         return 0;
 186 }
 187
 188
 189 /*
 190  * For outgoing IKE packets.  refresh timeouts for NAT & state entries, if
 191  * we can.  If they have disappeared, recreate them.
 192  */
 193 int ippr_ipsec_inout(fin, aps, nat)
 194 fr_info_t *fin;
 195 ap_session_t *aps;
 196 nat_t *nat;
 197 {
 198         ipsec_pxy_t *ipsec;
 199         fr_info_t fi;
 200         ip_t *ip;
 201         int p;
 202
 203         if ((fin->fin_out == 1) && (nat->nat_dir == NAT_INBOUND))
 204                 return 0;
 205
 206         if ((fin->fin_out == 0) && (nat->nat_dir == NAT_OUTBOUND))
 207                 return 0;
 208
 209         ipsec = aps->aps_data;
 210
 211         if (ipsec != NULL) {
 212                 ip = fin->fin_ip;
 213                 p = ip->ip_p;
 214
 215                 if ((ipsec->ipsc_nat == NULL) || (ipsec->ipsc_state == NULL)) {
 216                         bcopy((char *)fin, (char *)&fi, sizeof(fi));
 217                         fi.fin_state = NULL;
 218                         fi.fin_nat = NULL;
 219                         fi.fin_fi.fi_p = IPPROTO_ESP;
 220                         fi.fin_fr = &ipsecfr;
 221                         fi.fin_data[0] = 0;
 222                         fi.fin_data[1] = 0;
 223                         ip->ip_p = IPPROTO_ESP;
 224                         fi.fin_flx &= ~(FI_TCPUDP|FI_STATE|FI_FRAG);
 225                         fi.fin_flx |= FI_IGNORE;
 226                 }
 227
 228                 /*
 229                  * Update NAT timeout/create NAT if missing.
 230                  */
 231                 if (ipsec->ipsc_nat != NULL)
 232                         fr_queueback(&ipsec->ipsc_nat->nat_tqe);
 233                 else {
 234                         ipsec->ipsc_nat = nat_new(&fi, &ipsec->ipsc_rule,
 235                                                   &ipsec->ipsc_nat,
 236                                                   NAT_SLAVE|SI_WILDP,
 237                                                   nat->nat_dir);
 238                         if (ipsec->ipsc_nat != NULL) {
 239                                 (void) nat_proto(&fi, ipsec->ipsc_nat, 0);
 240                                 nat_update(&fi, ipsec->ipsc_nat,
 241                                            &ipsec->ipsc_rule);
 242                         }
 243                 }
 244
 245                 /*
 246                  * Update state timeout/create state if missing.
 247                  */
 248                 READ_ENTER(&ipf_state);
 249                 if (ipsec->ipsc_state != NULL) {
 250                         fr_queueback(&ipsec->ipsc_state->is_sti);
 251                         ipsec->ipsc_state->is_die = nat->nat_age;
 252                         RWLOCK_EXIT(&ipf_state);
 253                 } else {
 254                         RWLOCK_EXIT(&ipf_state);
 255                         fi.fin_data[0] = 0;
 256                         fi.fin_data[1] = 0;
 257                         ipsec->ipsc_state = fr_addstate(&fi,
 258                                                         &ipsec->ipsc_state,
 259                                                         SI_WILDP);
 260                         if (fi.fin_state != NULL)
 261                                 fr_statederef(&fi, (ipstate_t **)&fi.fin_state);
 262                 }
 263                 ip->ip_p = p;
 264         }
 265         return 0;
 266 }
 267
 268
 269 /*
 270  * This extends the NAT matching to be based on the cookies associated with
 271  * a session and found at the front of IKE packets.  The cookies are always
 272  * in the same order (not reversed depending on packet flow direction as with
 273  * UDP/TCP port numbers).
 274  */
 275 int ippr_ipsec_match(fin, aps, nat)
 276 fr_info_t *fin;
 277 ap_session_t *aps;
 278 nat_t *nat;
 279 {
 280         ipsec_pxy_t *ipsec;
 281         u_32_t cookies[4];
 282         mb_t *m;
 283         int off;
 284
 285         nat = nat;      /* LINT */
 286
 287         if ((fin->fin_dlen < sizeof(cookies)) || (fin->fin_flx & FI_FRAG))
 288                 return -1;
 289
 290         ipsec = aps->aps_data;
 291         off = fin->fin_hlen + sizeof(udphdr_t);
 292         m = fin->fin_m;
 293         COPYDATA(m, off, sizeof(cookies), (char *)cookies);
 294
 295         if ((cookies[0] != ipsec->ipsc_icookie[0]) ||
 296             (cookies[1] != ipsec->ipsc_icookie[1]))
 297                 return -1;
 298
 299         if (ipsec->ipsc_rckset == 0) {
 300                 if ((cookies[2]|cookies[3]) == 0) {
 301                         return 0;
 302                 }
 303                 ipsec->ipsc_rckset = 1;
 304                 ipsec->ipsc_rcookie[0] = cookies[2];
 305                 ipsec->ipsc_rcookie[1] = cookies[3];
 306                 return 0;
 307         }
 308
 309         if ((cookies[2] != ipsec->ipsc_rcookie[0]) ||
 310             (cookies[3] != ipsec->ipsc_rcookie[1]))
 311                 return -1;
 312         return 0;
 313 }
 314
 315
 316 /*
 317  * clean up after ourselves.
 318  */
 319 void ippr_ipsec_del(aps)
 320 ap_session_t *aps;
 321 {
 322         ipsec_pxy_t *ipsec;
 323
 324         ipsec = aps->aps_data;
 325
 326         if (ipsec != NULL) {
 327                 /*
 328                  * Don't bother changing any of the NAT structure details,
 329                  * *_del() is on a callback from aps_free(), from nat_delete()
 330                  */
 331
 332                 READ_ENTER(&ipf_state);
 333                 if (ipsec->ipsc_state != NULL) {
 334                         ipsec->ipsc_state->is_die = fr_ticks + 1;
 335                         ipsec->ipsc_state->is_me = NULL;
 336                         fr_queuefront(&ipsec->ipsc_state->is_sti);
 337                 }
 338                 RWLOCK_EXIT(&ipf_state);
 339
 340                 ipsec->ipsc_state = NULL;
 341                 ipsec->ipsc_nat = NULL;
 342         }
 343 }