sys/contrib/ipfilter/netinet/ip_ipsec_pxy.c

   1 /*
   2  * Copyright (C) 2001-2003 by Darren Reed
   3  *
   4  * See the IPFILTER.LICENCE file for details on licencing.
   5  *
   6  * Simple ISAKMP transparent proxy for in-kernel use.  For use with the NAT
   7  * code.
   8  *
   9  * $Id: ip_ipsec_pxy.c,v 2.20.2.8 2006/07/14 06:12:14 darrenr Exp $
  10  *
  11  */
  12 #define IPF_IPSEC_PROXY
  13
  14
  15 int ippr_ipsec_init __P((void));
  16 void ippr_ipsec_fini __P((void));
  17 int ippr_ipsec_new __P((fr_info_t *, ap_session_t *, nat_t *));
  18 void ippr_ipsec_del __P((ap_session_t *));
  19 int ippr_ipsec_inout __P((fr_info_t *, ap_session_t *, nat_t *));
  20 int ippr_ipsec_match __P((fr_info_t *, ap_session_t *, nat_t *));
  21
  22 static  frentry_t       ipsecfr;
  23 static  ipftq_t         *ipsecnattqe;
  24 static  ipftq_t         *ipsecstatetqe;
  25 static  char    ipsec_buffer[1500];
  26
  27 int     ipsec_proxy_init = 0;
  28 int     ipsec_proxy_ttl = 60;
  29
  30 /*
  31  * IPSec application proxy initialization.
  32  */
  33 int ippr_ipsec_init()
  34 {
  35         bzero((char *)&ipsecfr, sizeof(ipsecfr));
  36         ipsecfr.fr_ref = 1;
  37         ipsecfr.fr_flags = FR_OUTQUE|FR_PASS|FR_QUICK|FR_KEEPSTATE;
  38         MUTEX_INIT(&ipsecfr.fr_lock, "IPsec proxy rule lock");
  39         ipsec_proxy_init = 1;
  40
  41         ipsecnattqe = fr_addtimeoutqueue(&nat_utqe, ipsec_proxy_ttl);
  42         if (ipsecnattqe == NULL)
  43                 return -1;
  44         ipsecstatetqe = fr_addtimeoutqueue(&ips_utqe, ipsec_proxy_ttl);
  45         if (ipsecstatetqe == NULL) {
  46                 if (fr_deletetimeoutqueue(ipsecnattqe) == 0)
  47                         fr_freetimeoutqueue(ipsecnattqe);
  48                 ipsecnattqe = NULL;
  49                 return -1;
  50         }
  51
  52         ipsecnattqe->ifq_flags |= IFQF_PROXY;
  53         ipsecstatetqe->ifq_flags |= IFQF_PROXY;
  54
  55         ipsecfr.fr_age[0] = ipsec_proxy_ttl;
  56         ipsecfr.fr_age[1] = ipsec_proxy_ttl;
  57         return 0;
  58 }
  59
  60
  61 void ippr_ipsec_fini()
  62 {
  63         if (ipsecnattqe != NULL) {
  64                 if (fr_deletetimeoutqueue(ipsecnattqe) == 0)
  65                         fr_freetimeoutqueue(ipsecnattqe);
  66         }
  67         ipsecnattqe = NULL;
  68         if (ipsecstatetqe != NULL) {
  69                 if (fr_deletetimeoutqueue(ipsecstatetqe) == 0)
  70                         fr_freetimeoutqueue(ipsecstatetqe);
  71         }
  72         ipsecstatetqe = NULL;
  73
  74         if (ipsec_proxy_init == 1) {
  75                 MUTEX_DESTROY(&ipsecfr.fr_lock);
  76                 ipsec_proxy_init = 0;
  77         }
  78 }
  79
  80
  81 /*
  82  * Setup for a new IPSEC proxy.
  83  */
  84 int ippr_ipsec_new(fin, aps, nat)
  85 fr_info_t *fin;
  86 ap_session_t *aps;
  87 nat_t *nat;
  88 {
  89         ipsec_pxy_t *ipsec;
  90         fr_info_t fi;
  91         ipnat_t *ipn;
  92         char *ptr;
  93         int p, off, dlen, ttl;
  94         mb_t *m;
  95         ip_t *ip;
  96
  97         off = fin->fin_plen - fin->fin_dlen + fin->fin_ipoff;
  98         bzero(ipsec_buffer, sizeof(ipsec_buffer));
  99         ip = fin->fin_ip;
 100         m = fin->fin_m;
 101
 102         dlen = M_LEN(m) - off;
 103         if (dlen < 16)
 104                 return -1;
 105         COPYDATA(m, off, MIN(sizeof(ipsec_buffer), dlen), ipsec_buffer);
 106
 107         if (nat_outlookup(fin, 0, IPPROTO_ESP, nat->nat_inip,
 108                           ip->ip_dst) != NULL)
 109                 return -1;
 110
 111         aps->aps_psiz = sizeof(*ipsec);
 112         KMALLOCS(aps->aps_data, ipsec_pxy_t *, sizeof(*ipsec));
 113         if (aps->aps_data == NULL)
 114                 return -1;
 115
 116         ipsec = aps->aps_data;
 117         bzero((char *)ipsec, sizeof(*ipsec));
 118
 119         /*
 120          * Create NAT rule against which the tunnel/transport mapping is
 121          * created.  This is required because the current NAT rule does not
 122          * describe ESP but UDP instead.
 123          */
 124         ipn = &ipsec->ipsc_rule;
 125         ttl = IPF_TTLVAL(ipsecnattqe->ifq_ttl);
 126         ipn->in_tqehead[0] = fr_addtimeoutqueue(&nat_utqe, ttl);
 127         ipn->in_tqehead[1] = fr_addtimeoutqueue(&nat_utqe, ttl);
 128         ipn->in_ifps[0] = fin->fin_ifp;
 129         ipn->in_apr = NULL;
 130         ipn->in_use = 1;
 131         ipn->in_hits = 1;
 132         ipn->in_nip = ntohl(nat->nat_outip.s_addr);
 133         ipn->in_ippip = 1;
 134         ipn->in_inip = nat->nat_inip.s_addr;
 135         ipn->in_inmsk = 0xffffffff;
 136         ipn->in_outip = fin->fin_saddr;
 137         ipn->in_outmsk = nat->nat_outip.s_addr;
 138         ipn->in_srcip = fin->fin_saddr;
 139         ipn->in_srcmsk = 0xffffffff;
 140         ipn->in_redir = NAT_MAP;
 141         bcopy(nat->nat_ptr->in_ifnames[0], ipn->in_ifnames[0],
 142               sizeof(ipn->in_ifnames[0]));
 143         ipn->in_p = IPPROTO_ESP;
 144
 145         bcopy((char *)fin, (char *)&fi, sizeof(fi));
 146         fi.fin_state = NULL;
 147         fi.fin_nat = NULL;
 148         fi.fin_fi.fi_p = IPPROTO_ESP;
 149         fi.fin_fr = &ipsecfr;
 150         fi.fin_data[0] = 0;
 151         fi.fin_data[1] = 0;
 152         p = ip->ip_p;
 153         ip->ip_p = IPPROTO_ESP;
 154         fi.fin_flx &= ~(FI_TCPUDP|FI_STATE|FI_FRAG);
 155         fi.fin_flx |= FI_IGNORE;
 156
 157         ptr = ipsec_buffer;
 158         bcopy(ptr, (char *)ipsec->ipsc_icookie, sizeof(ipsec_cookie_t));
 159         ptr += sizeof(ipsec_cookie_t);
 160         bcopy(ptr, (char *)ipsec->ipsc_rcookie, sizeof(ipsec_cookie_t));
 161         /*
 162          * The responder cookie should only be non-zero if the initiator
 163          * cookie is non-zero.  Therefore, it is safe to assume(!) that the
 164          * cookies are both set after copying if the responder is non-zero.
 165          */
 166         if ((ipsec->ipsc_rcookie[0]|ipsec->ipsc_rcookie[1]) != 0)
 167                 ipsec->ipsc_rckset = 1;
 168
 169         ipsec->ipsc_nat = nat_new(&fi, ipn, &ipsec->ipsc_nat,
 170                                   NAT_SLAVE|SI_WILDP, NAT_OUTBOUND);
 171         if (ipsec->ipsc_nat != NULL) {
 172                 (void) nat_proto(&fi, ipsec->ipsc_nat, 0);
 173                 nat_update(&fi, ipsec->ipsc_nat, ipn);
 174
 175                 fi.fin_data[0] = 0;
 176                 fi.fin_data[1] = 0;
 177                 ipsec->ipsc_state = fr_addstate(&fi, &ipsec->ipsc_state,
 178                                                 SI_WILDP);
 179                 if (fi.fin_state != NULL)
 180                         fr_statederef((ipstate_t **)&fi.fin_state);
 181         }
 182         ip->ip_p = p & 0xff;
 183         return 0;
 184 }
 185
 186
 187 /*
 188  * For outgoing IKE packets.  refresh timeouts for NAT & state entries, if
 189  * we can.  If they have disappeared, recreate them.
 190  */
 191 int ippr_ipsec_inout(fin, aps, nat)
 192 fr_info_t *fin;
 193 ap_session_t *aps;
 194 nat_t *nat;
 195 {
 196         ipsec_pxy_t *ipsec;
 197         fr_info_t fi;
 198         ip_t *ip;
 199         int p;
 200
 201         if ((fin->fin_out == 1) && (nat->nat_dir == NAT_INBOUND))
 202                 return 0;
 203
 204         if ((fin->fin_out == 0) && (nat->nat_dir == NAT_OUTBOUND))
 205                 return 0;
 206
 207         ipsec = aps->aps_data;
 208
 209         if (ipsec != NULL) {
 210                 ip = fin->fin_ip;
 211                 p = ip->ip_p;
 212
 213                 if ((ipsec->ipsc_nat == NULL) || (ipsec->ipsc_state == NULL)) {
 214                         bcopy((char *)fin, (char *)&fi, sizeof(fi));
 215                         fi.fin_state = NULL;
 216                         fi.fin_nat = NULL;
 217                         fi.fin_fi.fi_p = IPPROTO_ESP;
 218                         fi.fin_fr = &ipsecfr;
 219                         fi.fin_data[0] = 0;
 220                         fi.fin_data[1] = 0;
 221                         ip->ip_p = IPPROTO_ESP;
 222                         fi.fin_flx &= ~(FI_TCPUDP|FI_STATE|FI_FRAG);
 223                         fi.fin_flx |= FI_IGNORE;
 224                 }
 225
 226                 /*
 227                  * Update NAT timeout/create NAT if missing.
 228                  */
 229                 if (ipsec->ipsc_nat != NULL)
 230                         fr_queueback(&ipsec->ipsc_nat->nat_tqe);
 231                 else {
 232                         ipsec->ipsc_nat = nat_new(&fi, &ipsec->ipsc_rule,
 233                                                   &ipsec->ipsc_nat,
 234                                                   NAT_SLAVE|SI_WILDP,
 235                                                   nat->nat_dir);
 236                         if (ipsec->ipsc_nat != NULL) {
 237                                 (void) nat_proto(&fi, ipsec->ipsc_nat, 0);
 238                                 nat_update(&fi, ipsec->ipsc_nat,
 239                                            &ipsec->ipsc_rule);
 240                         }
 241                 }
 242
 243                 /*
 244                  * Update state timeout/create state if missing.
 245                  */
 246                 READ_ENTER(&ipf_state);
 247                 if (ipsec->ipsc_state != NULL) {
 248                         fr_queueback(&ipsec->ipsc_state->is_sti);
 249                         ipsec->ipsc_state->is_die = nat->nat_age;
 250                         RWLOCK_EXIT(&ipf_state);
 251                 } else {
 252                         RWLOCK_EXIT(&ipf_state);
 253                         fi.fin_data[0] = 0;
 254                         fi.fin_data[1] = 0;
 255                         ipsec->ipsc_state = fr_addstate(&fi,
 256                                                         &ipsec->ipsc_state,
 257                                                         SI_WILDP);
 258                         if (fi.fin_state != NULL)
 259                                 fr_statederef((ipstate_t **)&fi.fin_state);
 260                 }
 261                 ip->ip_p = p;
 262         }
 263         return 0;
 264 }
 265
 266
 267 /*
 268  * This extends the NAT matching to be based on the cookies associated with
 269  * a session and found at the front of IKE packets.  The cookies are always
 270  * in the same order (not reversed depending on packet flow direction as with
 271  * UDP/TCP port numbers).
 272  */
 273 int ippr_ipsec_match(fin, aps, nat)
 274 fr_info_t *fin;
 275 ap_session_t *aps;
 276 nat_t *nat;
 277 {
 278         ipsec_pxy_t *ipsec;
 279         u_32_t cookies[4];
 280         mb_t *m;
 281         int off;
 282
 283         nat = nat;      /* LINT */
 284
 285         if ((fin->fin_dlen < sizeof(cookies)) || (fin->fin_flx & FI_FRAG))
 286                 return -1;
 287
 288         off = fin->fin_plen - fin->fin_dlen + fin->fin_ipoff;
 289         ipsec = aps->aps_data;
 290         m = fin->fin_m;
 291         COPYDATA(m, off, sizeof(cookies), (char *)cookies);
 292
 293         if ((cookies[0] != ipsec->ipsc_icookie[0]) ||
 294             (cookies[1] != ipsec->ipsc_icookie[1]))
 295                 return -1;
 296
 297         if (ipsec->ipsc_rckset == 0) {
 298                 if ((cookies[2]|cookies[3]) == 0) {
 299                         return 0;
 300                 }
 301                 ipsec->ipsc_rckset = 1;
 302                 ipsec->ipsc_rcookie[0] = cookies[2];
 303                 ipsec->ipsc_rcookie[1] = cookies[3];
 304                 return 0;
 305         }
 306
 307         if ((cookies[2] != ipsec->ipsc_rcookie[0]) ||
 308             (cookies[3] != ipsec->ipsc_rcookie[1]))
 309                 return -1;
 310         return 0;
 311 }
 312
 313
 314 /*
 315  * clean up after ourselves.
 316  */
 317 void ippr_ipsec_del(aps)
 318 ap_session_t *aps;
 319 {
 320         ipsec_pxy_t *ipsec;
 321
 322         ipsec = aps->aps_data;
 323
 324         if (ipsec != NULL) {
 325                 /*
 326                  * Don't bother changing any of the NAT structure details,
 327                  * *_del() is on a callback from aps_free(), from nat_delete()
 328                  */
 329
 330                 READ_ENTER(&ipf_state);
 331                 if (ipsec->ipsc_state != NULL) {
 332                         ipsec->ipsc_state->is_die = fr_ticks + 1;
 333                         ipsec->ipsc_state->is_me = NULL;
 334                         fr_queuefront(&ipsec->ipsc_state->is_sti);
 335                 }
 336                 RWLOCK_EXIT(&ipf_state);
 337
 338                 ipsec->ipsc_state = NULL;
 339                 ipsec->ipsc_nat = NULL;
 340         }
 341 }