src/ap/iapp.c

   1 /*
   2  * hostapd / IEEE 802.11F-2003 Inter-Access Point Protocol (IAPP)
   3  * Copyright (c) 2002-2007, Jouni Malinen <j@w1.fi>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  *
   9  * Alternatively, this software may be distributed under the terms of BSD
  10  * license.
  11  *
  12  * See README and COPYING for more details.
  13  *
  14  * Note: IEEE 802.11F-2003 was a experimental use specification. It has expired
  15  * and IEEE has withdrawn it. In other words, it is likely better to look at
  16  * using some other mechanism for AP-to-AP communication than extending the
  17  * implementation here.
  18  */
  19
  20 /* TODO:
  21  * Level 1: no administrative or security support
  22  *      (e.g., static BSSID to IP address mapping in each AP)
  23  * Level 2: support for dynamic mapping of BSSID to IP address
  24  * Level 3: support for encryption and authentication of IAPP messages
  25  * - add support for MOVE-notify and MOVE-response (this requires support for
  26  *   finding out IP address for previous AP using RADIUS)
  27  * - add support for Send- and ACK-Security-Block to speedup IEEE 802.1X during
  28  *   reassociation to another AP
  29  * - implement counters etc. for IAPP MIB
  30  * - verify endianness of fields in IAPP messages; are they big-endian as
  31  *   used here?
  32  * - RADIUS connection for AP registration and BSSID to IP address mapping
  33  * - TCP connection for IAPP MOVE, CACHE
  34  * - broadcast ESP for IAPP ADD-notify
  35  * - ESP for IAPP MOVE messages
  36  * - security block sending/processing
  37  * - IEEE 802.11 context transfer
  38  */
  39
  40 #include "utils/includes.h"
  41 #include <net/if.h>
  42 #include <sys/ioctl.h>
  43 #ifdef USE_KERNEL_HEADERS
  44 #include <linux/if_packet.h>
  45 #else /* USE_KERNEL_HEADERS */
  46 #include <netpacket/packet.h>
  47 #endif /* USE_KERNEL_HEADERS */
  48
  49 #include "utils/common.h"
  50 #include "utils/eloop.h"
  51 #include "hostapd.h"
  52 #include "ap_config.h"
  53 #include "ieee802_11.h"
  54 #include "sta_info.h"
  55 #include "iapp.h"
  56
  57
  58 #define IAPP_MULTICAST "224.0.1.178"
  59 #define IAPP_UDP_PORT 3517
  60 #define IAPP_TCP_PORT 3517
  61
  62 struct iapp_hdr {
  63         u8 version;
  64         u8 command;
  65         be16 identifier;
  66         be16 length;
  67         /* followed by length-6 octets of data */
  68 } __attribute__ ((packed));
  69
  70 #define IAPP_VERSION 0
  71
  72 enum IAPP_COMMAND {
  73         IAPP_CMD_ADD_notify = 0,
  74         IAPP_CMD_MOVE_notify = 1,
  75         IAPP_CMD_MOVE_response = 2,
  76         IAPP_CMD_Send_Security_Block = 3,
  77         IAPP_CMD_ACK_Security_Block = 4,
  78         IAPP_CMD_CACHE_notify = 5,
  79         IAPP_CMD_CACHE_response = 6,
  80 };
  81
  82
  83 /* ADD-notify - multicast UDP on the local LAN */
  84 struct iapp_add_notify {
  85         u8 addr_len; /* ETH_ALEN */
  86         u8 reserved;
  87         u8 mac_addr[ETH_ALEN];
  88         be16 seq_num;
  89 } __attribute__ ((packed));
  90
  91
  92 /* Layer 2 Update frame (802.2 Type 1 LLC XID Update response) */
  93 struct iapp_layer2_update {
  94         u8 da[ETH_ALEN]; /* broadcast */
  95         u8 sa[ETH_ALEN]; /* STA addr */
  96         be16 len; /* 6 */
  97         u8 dsap; /* null DSAP address */
  98         u8 ssap; /* null SSAP address, CR=Response */
  99         u8 control;
 100         u8 xid_info[3];
 101 } __attribute__ ((packed));
 102
 103
 104 /* MOVE-notify - unicast TCP */
 105 struct iapp_move_notify {
 106         u8 addr_len; /* ETH_ALEN */
 107         u8 reserved;
 108         u8 mac_addr[ETH_ALEN];
 109         u16 seq_num;
 110         u16 ctx_block_len;
 111         /* followed by ctx_block_len bytes */
 112 } __attribute__ ((packed));
 113
 114
 115 /* MOVE-response - unicast TCP */
 116 struct iapp_move_response {
 117         u8 addr_len; /* ETH_ALEN */
 118         u8 status;
 119         u8 mac_addr[ETH_ALEN];
 120         u16 seq_num;
 121         u16 ctx_block_len;
 122         /* followed by ctx_block_len bytes */
 123 } __attribute__ ((packed));
 124
 125 enum {
 126         IAPP_MOVE_SUCCESSFUL = 0,
 127         IAPP_MOVE_DENIED = 1,
 128         IAPP_MOVE_STALE_MOVE = 2,
 129 };
 130
 131
 132 /* CACHE-notify */
 133 struct iapp_cache_notify {
 134         u8 addr_len; /* ETH_ALEN */
 135         u8 reserved;
 136         u8 mac_addr[ETH_ALEN];
 137         u16 seq_num;
 138         u8 current_ap[ETH_ALEN];
 139         u16 ctx_block_len;
 140         /* ctx_block_len bytes of context block followed by 16-bit context
 141          * timeout */
 142 } __attribute__ ((packed));
 143
 144
 145 /* CACHE-response - unicast TCP */
 146 struct iapp_cache_response {
 147         u8 addr_len; /* ETH_ALEN */
 148         u8 status;
 149         u8 mac_addr[ETH_ALEN];
 150         u16 seq_num;
 151 } __attribute__ ((packed));
 152
 153 enum {
 154         IAPP_CACHE_SUCCESSFUL = 0,
 155         IAPP_CACHE_STALE_CACHE = 1,
 156 };
 157
 158
 159 /* Send-Security-Block - unicast TCP */
 160 struct iapp_send_security_block {
 161         u8 iv[8];
 162         u16 sec_block_len;
 163         /* followed by sec_block_len bytes of security block */
 164 } __attribute__ ((packed));
 165
 166
 167 /* ACK-Security-Block - unicast TCP */
 168 struct iapp_ack_security_block {
 169         u8 iv[8];
 170         u8 new_ap_ack_authenticator[48];
 171 } __attribute__ ((packed));
 172
 173
 174 struct iapp_data {
 175         struct hostapd_data *hapd;
 176         u16 identifier; /* next IAPP identifier */
 177         struct in_addr own, multicast;
 178         int udp_sock;
 179         int packet_sock;
 180 };
 181
 182
 183 static void iapp_send_add(struct iapp_data *iapp, u8 *mac_addr, u16 seq_num)
 184 {
 185         char buf[128];
 186         struct iapp_hdr *hdr;
 187         struct iapp_add_notify *add;
 188         struct sockaddr_in addr;
 189
 190         /* Send IAPP ADD-notify to remove possible association from other APs
 191          */
 192
 193         hdr = (struct iapp_hdr *) buf;
 194         hdr->version = IAPP_VERSION;
 195         hdr->command = IAPP_CMD_ADD_notify;
 196         hdr->identifier = host_to_be16(iapp->identifier++);
 197         hdr->length = host_to_be16(sizeof(*hdr) + sizeof(*add));
 198
 199         add = (struct iapp_add_notify *) (hdr + 1);
 200         add->addr_len = ETH_ALEN;
 201         add->reserved = 0;
 202         os_memcpy(add->mac_addr, mac_addr, ETH_ALEN);
 203
 204         add->seq_num = host_to_be16(seq_num);
 205
 206         os_memset(&addr, 0, sizeof(addr));
 207         addr.sin_family = AF_INET;
 208         addr.sin_addr.s_addr = iapp->multicast.s_addr;
 209         addr.sin_port = htons(IAPP_UDP_PORT);
 210         if (sendto(iapp->udp_sock, buf, (char *) (add + 1) - buf, 0,
 211                    (struct sockaddr *) &addr, sizeof(addr)) < 0)
 212                 perror("sendto[IAPP-ADD]");
 213 }
 214
 215
 216 static void iapp_send_layer2_update(struct iapp_data *iapp, u8 *addr)
 217 {
 218         struct iapp_layer2_update msg;
 219
 220         /* Send Level 2 Update Frame to update forwarding tables in layer 2
 221          * bridge devices */
 222
 223         /* 802.2 Type 1 Logical Link Control (LLC) Exchange Identifier (XID)
 224          * Update response frame; IEEE Std 802.2-1998, 5.4.1.2.1 */
 225
 226         os_memset(msg.da, 0xff, ETH_ALEN);
 227         os_memcpy(msg.sa, addr, ETH_ALEN);
 228         msg.len = host_to_be16(6);
 229         msg.dsap = 0; /* NULL DSAP address */
 230         msg.ssap = 0x01; /* NULL SSAP address, CR Bit: Response */
 231         msg.control = 0xaf; /* XID response lsb.1111F101.
 232                              * F=0 (no poll command; unsolicited frame) */
 233         msg.xid_info[0] = 0x81; /* XID format identifier */
 234         msg.xid_info[1] = 1; /* LLC types/classes: Type 1 LLC */
 235         msg.xid_info[2] = 1 << 1; /* XID sender's receive window size (RW)
 236                                    * FIX: what is correct RW with 802.11? */
 237
 238         if (send(iapp->packet_sock, &msg, sizeof(msg), 0) < 0)
 239                 perror("send[L2 Update]");
 240 }
 241
 242
 243 /**
 244  * iapp_new_station - IAPP processing for a new STA
 245  * @iapp: IAPP data
 246  * @sta: The associated station
 247  */
 248 void iapp_new_station(struct iapp_data *iapp, struct sta_info *sta)
 249 {
 250         struct ieee80211_mgmt *assoc;
 251         u16 seq;
 252
 253         if (iapp == NULL)
 254                 return;
 255
 256         assoc = sta->last_assoc_req;
 257         seq = assoc ? WLAN_GET_SEQ_SEQ(le_to_host16(assoc->seq_ctrl)) : 0;
 258
 259         /* IAPP-ADD.request(MAC Address, Sequence Number, Timeout) */
 260         hostapd_logger(iapp->hapd, sta->addr, HOSTAPD_MODULE_IAPP,
 261                        HOSTAPD_LEVEL_DEBUG, "IAPP-ADD.request(seq=%d)", seq);
 262         iapp_send_layer2_update(iapp, sta->addr);
 263         iapp_send_add(iapp, sta->addr, seq);
 264
 265         if (assoc && WLAN_FC_GET_STYPE(le_to_host16(assoc->frame_control)) ==
 266             WLAN_FC_STYPE_REASSOC_REQ) {
 267                 /* IAPP-MOVE.request(MAC Address, Sequence Number, Old AP,
 268                  *                   Context Block, Timeout)
 269                  */
 270                 /* TODO: Send IAPP-MOVE to the old AP; Map Old AP BSSID to
 271                  * IP address */
 272         }
 273 }
 274
 275
 276 static void iapp_process_add_notify(struct iapp_data *iapp,
 277                                     struct sockaddr_in *from,
 278                                     struct iapp_hdr *hdr, int len)
 279 {
 280         struct iapp_add_notify *add = (struct iapp_add_notify *) (hdr + 1);
 281         struct sta_info *sta;
 282
 283         if (len != sizeof(*add)) {
 284                 printf("Invalid IAPP-ADD packet length %d (expected %lu)\n",
 285                        len, (unsigned long) sizeof(*add));
 286                 return;
 287         }
 288
 289         sta = ap_get_sta(iapp->hapd, add->mac_addr);
 290
 291         /* IAPP-ADD.indication(MAC Address, Sequence Number) */
 292         hostapd_logger(iapp->hapd, add->mac_addr, HOSTAPD_MODULE_IAPP,
 293                        HOSTAPD_LEVEL_INFO,
 294                        "Received IAPP ADD-notify (seq# %d) from %s:%d%s",
 295                        be_to_host16(add->seq_num),
 296                        inet_ntoa(from->sin_addr), ntohs(from->sin_port),
 297                        sta ? "" : " (STA not found)");
 298
 299         if (!sta)
 300                 return;
 301
 302         /* TODO: could use seq_num to try to determine whether last association
 303          * to this AP is newer than the one advertised in IAPP-ADD. Although,
 304          * this is not really a reliable verification. */
 305
 306         hostapd_logger(iapp->hapd, add->mac_addr, HOSTAPD_MODULE_IAPP,
 307                        HOSTAPD_LEVEL_DEBUG,
 308                        "Removing STA due to IAPP ADD-notify");
 309         ap_sta_disconnect(iapp->hapd, sta, NULL, 0);
 310 }
 311
 312
 313 /**
 314  * iapp_receive_udp - Process IAPP UDP frames
 315  * @sock: File descriptor for the socket
 316  * @eloop_ctx: IAPP data (struct iapp_data *)
 317  * @sock_ctx: Not used
 318  */
 319 static void iapp_receive_udp(int sock, void *eloop_ctx, void *sock_ctx)
 320 {
 321         struct iapp_data *iapp = eloop_ctx;
 322         int len, hlen;
 323         unsigned char buf[128];
 324         struct sockaddr_in from;
 325         socklen_t fromlen;
 326         struct iapp_hdr *hdr;
 327
 328         /* Handle incoming IAPP frames (over UDP/IP) */
 329
 330         fromlen = sizeof(from);
 331         len = recvfrom(iapp->udp_sock, buf, sizeof(buf), 0,
 332                        (struct sockaddr *) &from, &fromlen);
 333         if (len < 0) {
 334                 perror("recvfrom");
 335                 return;
 336         }
 337
 338         if (from.sin_addr.s_addr == iapp->own.s_addr)
 339                 return; /* ignore own IAPP messages */
 340
 341         hostapd_logger(iapp->hapd, NULL, HOSTAPD_MODULE_IAPP,
 342                        HOSTAPD_LEVEL_DEBUG,
 343                        "Received %d byte IAPP frame from %s%s\n",
 344                        len, inet_ntoa(from.sin_addr),
 345                        len < (int) sizeof(*hdr) ? " (too short)" : "");
 346
 347         if (len < (int) sizeof(*hdr))
 348                 return;
 349
 350         hdr = (struct iapp_hdr *) buf;
 351         hlen = be_to_host16(hdr->length);
 352         hostapd_logger(iapp->hapd, NULL, HOSTAPD_MODULE_IAPP,
 353                        HOSTAPD_LEVEL_DEBUG,
 354                        "RX: version=%d command=%d id=%d len=%d\n",
 355                        hdr->version, hdr->command,
 356                        be_to_host16(hdr->identifier), hlen);
 357         if (hdr->version != IAPP_VERSION) {
 358                 printf("Dropping IAPP frame with unknown version %d\n",
 359                        hdr->version);
 360                 return;
 361         }
 362         if (hlen > len) {
 363                 printf("Underflow IAPP frame (hlen=%d len=%d)\n", hlen, len);
 364                 return;
 365         }
 366         if (hlen < len) {
 367                 printf("Ignoring %d extra bytes from IAPP frame\n",
 368                        len - hlen);
 369                 len = hlen;
 370         }
 371
 372         switch (hdr->command) {
 373         case IAPP_CMD_ADD_notify:
 374                 iapp_process_add_notify(iapp, &from, hdr, hlen - sizeof(*hdr));
 375                 break;
 376         case IAPP_CMD_MOVE_notify:
 377                 /* TODO: MOVE is using TCP; so move this to TCP handler once it
 378                  * is implemented.. */
 379                 /* IAPP-MOVE.indication(MAC Address, New BSSID,
 380                  * Sequence Number, AP Address, Context Block) */
 381                 /* TODO: process */
 382                 break;
 383         default:
 384                 printf("Unknown IAPP command %d\n", hdr->command);
 385                 break;
 386         }
 387 }
 388
 389
 390 struct iapp_data * iapp_init(struct hostapd_data *hapd, const char *iface)
 391 {
 392         struct ifreq ifr;
 393         struct sockaddr_ll addr;
 394         int ifindex;
 395         struct sockaddr_in *paddr, uaddr;
 396         struct iapp_data *iapp;
 397         struct ip_mreqn mreq;
 398
 399         iapp = os_zalloc(sizeof(*iapp));
 400         if (iapp == NULL)
 401                 return NULL;
 402         iapp->hapd = hapd;
 403         iapp->udp_sock = iapp->packet_sock = -1;
 404
 405         /* TODO:
 406          * open socket for sending and receiving IAPP frames over TCP
 407          */
 408
 409         iapp->udp_sock = socket(PF_INET, SOCK_DGRAM, 0);
 410         if (iapp->udp_sock < 0) {
 411                 perror("socket[PF_INET,SOCK_DGRAM]");
 412                 iapp_deinit(iapp);
 413                 return NULL;
 414         }
 415
 416         os_memset(&ifr, 0, sizeof(ifr));
 417         os_strlcpy(ifr.ifr_name, iface, sizeof(ifr.ifr_name));
 418         if (ioctl(iapp->udp_sock, SIOCGIFINDEX, &ifr) != 0) {
 419                 perror("ioctl(SIOCGIFINDEX)");
 420                 iapp_deinit(iapp);
 421                 return NULL;
 422         }
 423         ifindex = ifr.ifr_ifindex;
 424
 425         if (ioctl(iapp->udp_sock, SIOCGIFADDR, &ifr) != 0) {
 426                 perror("ioctl(SIOCGIFADDR)");
 427                 iapp_deinit(iapp);
 428                 return NULL;
 429         }
 430         paddr = (struct sockaddr_in *) &ifr.ifr_addr;
 431         if (paddr->sin_family != AF_INET) {
 432                 printf("Invalid address family %i (SIOCGIFADDR)\n",
 433                        paddr->sin_family);
 434                 iapp_deinit(iapp);
 435                 return NULL;
 436         }
 437         iapp->own.s_addr = paddr->sin_addr.s_addr;
 438
 439         if (ioctl(iapp->udp_sock, SIOCGIFBRDADDR, &ifr) != 0) {
 440                 perror("ioctl(SIOCGIFBRDADDR)");
 441                 iapp_deinit(iapp);
 442                 return NULL;
 443         }
 444         paddr = (struct sockaddr_in *) &ifr.ifr_addr;
 445         if (paddr->sin_family != AF_INET) {
 446                 printf("Invalid address family %i (SIOCGIFBRDADDR)\n",
 447                        paddr->sin_family);
 448                 iapp_deinit(iapp);
 449                 return NULL;
 450         }
 451         inet_aton(IAPP_MULTICAST, &iapp->multicast);
 452
 453         os_memset(&uaddr, 0, sizeof(uaddr));
 454         uaddr.sin_family = AF_INET;
 455         uaddr.sin_port = htons(IAPP_UDP_PORT);
 456         if (bind(iapp->udp_sock, (struct sockaddr *) &uaddr,
 457                  sizeof(uaddr)) < 0) {
 458                 perror("bind[UDP]");
 459                 iapp_deinit(iapp);
 460                 return NULL;
 461         }
 462
 463         os_memset(&mreq, 0, sizeof(mreq));
 464         mreq.imr_multiaddr = iapp->multicast;
 465         mreq.imr_address.s_addr = INADDR_ANY;
 466         mreq.imr_ifindex = 0;
 467         if (setsockopt(iapp->udp_sock, SOL_IP, IP_ADD_MEMBERSHIP, &mreq,
 468                        sizeof(mreq)) < 0) {
 469                 perror("setsockopt[UDP,IP_ADD_MEMBERSHIP]");
 470                 iapp_deinit(iapp);
 471                 return NULL;
 472         }
 473
 474         iapp->packet_sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
 475         if (iapp->packet_sock < 0) {
 476                 perror("socket[PF_PACKET,SOCK_RAW]");
 477                 iapp_deinit(iapp);
 478                 return NULL;
 479         }
 480
 481         os_memset(&addr, 0, sizeof(addr));
 482         addr.sll_family = AF_PACKET;
 483         addr.sll_ifindex = ifindex;
 484         if (bind(iapp->packet_sock, (struct sockaddr *) &addr,
 485                  sizeof(addr)) < 0) {
 486                 perror("bind[PACKET]");
 487                 iapp_deinit(iapp);
 488                 return NULL;
 489         }
 490
 491         if (eloop_register_read_sock(iapp->udp_sock, iapp_receive_udp,
 492                                      iapp, NULL)) {
 493                 printf("Could not register read socket for IAPP.\n");
 494                 iapp_deinit(iapp);
 495                 return NULL;
 496         }
 497
 498         printf("IEEE 802.11F (IAPP) using interface %s\n", iface);
 499
 500         /* TODO: For levels 2 and 3: send RADIUS Initiate-Request, receive
 501          * RADIUS Initiate-Accept or Initiate-Reject. IAPP port should actually
 502          * be openned only after receiving Initiate-Accept. If Initiate-Reject
 503          * is received, IAPP is not started. */
 504
 505         return iapp;
 506 }
 507
 508
 509 void iapp_deinit(struct iapp_data *iapp)
 510 {
 511         struct ip_mreqn mreq;
 512
 513         if (iapp == NULL)
 514                 return;
 515
 516         if (iapp->udp_sock >= 0) {
 517                 os_memset(&mreq, 0, sizeof(mreq));
 518                 mreq.imr_multiaddr = iapp->multicast;
 519                 mreq.imr_address.s_addr = INADDR_ANY;
 520                 mreq.imr_ifindex = 0;
 521                 if (setsockopt(iapp->udp_sock, SOL_IP, IP_DROP_MEMBERSHIP,
 522                                &mreq, sizeof(mreq)) < 0) {
 523                         perror("setsockopt[UDP,IP_DEL_MEMBERSHIP]");
 524                 }
 525
 526                 eloop_unregister_read_sock(iapp->udp_sock);
 527                 close(iapp->udp_sock);
 528         }
 529         if (iapp->packet_sock >= 0) {
 530                 eloop_unregister_read_sock(iapp->packet_sock);
 531                 close(iapp->packet_sock);
 532         }
 533         os_free(iapp);
 534 }