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  15  * and IEEE has withdrawn it.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 "common/ieee802_11_defs.h"
  52 #include "hostapd.h"
  53 #include "ap_config.h"
  54 #include "ieee802_11.h"
  55 #include "sta_info.h"
  56 #include "iapp.h"
  57
  58
  59 #define IAPP_MULTICAST "224.0.1.178"
  60 #define IAPP_UDP_PORT 3517
  61 #define IAPP_TCP_PORT 3517
  62
  63 struct iapp_hdr {
  64         u8 version;
  65         u8 command;
  66         be16 identifier;
  67         be16 length;
  68         /* followed by length-6 octets of data */
  69 } __attribute__ ((packed));
  70
  71 #define IAPP_VERSION 0
  72
  73 enum IAPP_COMMAND {
  74         IAPP_CMD_ADD_notify = 0,
  75         IAPP_CMD_MOVE_notify = 1,
  76         IAPP_CMD_MOVE_response = 2,
  77         IAPP_CMD_Send_Security_Block = 3,
  78         IAPP_CMD_ACK_Security_Block = 4,
  79         IAPP_CMD_CACHE_notify = 5,
  80         IAPP_CMD_CACHE_response = 6,
  81 };
  82
  83
  84 /* ADD-notify - multicast UDP on the local LAN */
  85 struct iapp_add_notify {
  86         u8 addr_len; /* ETH_ALEN */
  87         u8 reserved;
  88         u8 mac_addr[ETH_ALEN];
  89         be16 seq_num;
  90 } __attribute__ ((packed));
  91
  92
  93 /* Layer 2 Update frame (802.2 Type 1 LLC XID Update response) */
  94 struct iapp_layer2_update {
  95         u8 da[ETH_ALEN]; /* broadcast */
  96         u8 sa[ETH_ALEN]; /* STA addr */
  97         be16 len; /* 6 */
  98         u8 dsap; /* null DSAP address */
  99         u8 ssap; /* null SSAP address, CR=Response */
 100         u8 control;
 101         u8 xid_info[3];
 102 } __attribute__ ((packed));
 103
 104
 105 /* MOVE-notify - unicast TCP */
 106 struct iapp_move_notify {
 107         u8 addr_len; /* ETH_ALEN */
 108         u8 reserved;
 109         u8 mac_addr[ETH_ALEN];
 110         u16 seq_num;
 111         u16 ctx_block_len;
 112         /* followed by ctx_block_len bytes */
 113 } __attribute__ ((packed));
 114
 115
 116 /* MOVE-response - unicast TCP */
 117 struct iapp_move_response {
 118         u8 addr_len; /* ETH_ALEN */
 119         u8 status;
 120         u8 mac_addr[ETH_ALEN];
 121         u16 seq_num;
 122         u16 ctx_block_len;
 123         /* followed by ctx_block_len bytes */
 124 } __attribute__ ((packed));
 125
 126 enum {
 127         IAPP_MOVE_SUCCESSFUL = 0,
 128         IAPP_MOVE_DENIED = 1,
 129         IAPP_MOVE_STALE_MOVE = 2,
 130 };
 131
 132
 133 /* CACHE-notify */
 134 struct iapp_cache_notify {
 135         u8 addr_len; /* ETH_ALEN */
 136         u8 reserved;
 137         u8 mac_addr[ETH_ALEN];
 138         u16 seq_num;
 139         u8 current_ap[ETH_ALEN];
 140         u16 ctx_block_len;
 141         /* ctx_block_len bytes of context block followed by 16-bit context
 142          * timeout */
 143 } __attribute__ ((packed));
 144
 145
 146 /* CACHE-response - unicast TCP */
 147 struct iapp_cache_response {
 148         u8 addr_len; /* ETH_ALEN */
 149         u8 status;
 150         u8 mac_addr[ETH_ALEN];
 151         u16 seq_num;
 152 } __attribute__ ((packed));
 153
 154 enum {
 155         IAPP_CACHE_SUCCESSFUL = 0,
 156         IAPP_CACHE_STALE_CACHE = 1,
 157 };
 158
 159
 160 /* Send-Security-Block - unicast TCP */
 161 struct iapp_send_security_block {
 162         u8 iv[8];
 163         u16 sec_block_len;
 164         /* followed by sec_block_len bytes of security block */
 165 } __attribute__ ((packed));
 166
 167
 168 /* ACK-Security-Block - unicast TCP */
 169 struct iapp_ack_security_block {
 170         u8 iv[8];
 171         u8 new_ap_ack_authenticator[48];
 172 } __attribute__ ((packed));
 173
 174
 175 struct iapp_data {
 176         struct hostapd_data *hapd;
 177         u16 identifier; /* next IAPP identifier */
 178         struct in_addr own, multicast;
 179         int udp_sock;
 180         int packet_sock;
 181 };
 182
 183
 184 static void iapp_send_add(struct iapp_data *iapp, u8 *mac_addr, u16 seq_num)
 185 {
 186         char buf[128];
 187         struct iapp_hdr *hdr;
 188         struct iapp_add_notify *add;
 189         struct sockaddr_in addr;
 190
 191         /* Send IAPP ADD-notify to remove possible association from other APs
 192          */
 193
 194         hdr = (struct iapp_hdr *) buf;
 195         hdr->version = IAPP_VERSION;
 196         hdr->command = IAPP_CMD_ADD_notify;
 197         hdr->identifier = host_to_be16(iapp->identifier++);
 198         hdr->length = host_to_be16(sizeof(*hdr) + sizeof(*add));
 199
 200         add = (struct iapp_add_notify *) (hdr + 1);
 201         add->addr_len = ETH_ALEN;
 202         add->reserved = 0;
 203         os_memcpy(add->mac_addr, mac_addr, ETH_ALEN);
 204
 205         add->seq_num = host_to_be16(seq_num);
 206
 207         os_memset(&addr, 0, sizeof(addr));
 208         addr.sin_family = AF_INET;
 209         addr.sin_addr.s_addr = iapp->multicast.s_addr;
 210         addr.sin_port = htons(IAPP_UDP_PORT);
 211         if (sendto(iapp->udp_sock, buf, (char *) (add + 1) - buf, 0,
 212                    (struct sockaddr *) &addr, sizeof(addr)) < 0)
 213                 perror("sendto[IAPP-ADD]");
 214 }
 215
 216
 217 static void iapp_send_layer2_update(struct iapp_data *iapp, u8 *addr)
 218 {
 219         struct iapp_layer2_update msg;
 220
 221         /* Send Level 2 Update Frame to update forwarding tables in layer 2
 222          * bridge devices */
 223
 224         /* 802.2 Type 1 Logical Link Control (LLC) Exchange Identifier (XID)
 225          * Update response frame; IEEE Std 802.2-1998, 5.4.1.2.1 */
 226
 227         os_memset(msg.da, 0xff, ETH_ALEN);
 228         os_memcpy(msg.sa, addr, ETH_ALEN);
 229         msg.len = host_to_be16(6);
 230         msg.dsap = 0; /* NULL DSAP address */
 231         msg.ssap = 0x01; /* NULL SSAP address, CR Bit: Response */
 232         msg.control = 0xaf; /* XID response lsb.1111F101.
 233                              * F=0 (no poll command; unsolicited frame) */
 234         msg.xid_info[0] = 0x81; /* XID format identifier */
 235         msg.xid_info[1] = 1; /* LLC types/classes: Type 1 LLC */
 236         msg.xid_info[2] = 1 << 1; /* XID sender's receive window size (RW)
 237                                    * FIX: what is correct RW with 802.11? */
 238
 239         if (send(iapp->packet_sock, &msg, sizeof(msg), 0) < 0)
 240                 perror("send[L2 Update]");
 241 }
 242
 243
 244 /**
 245  * iapp_new_station - IAPP processing for a new STA
 246  * @iapp: IAPP data
 247  * @sta: The associated station
 248  */
 249 void iapp_new_station(struct iapp_data *iapp, struct sta_info *sta)
 250 {
 251         struct ieee80211_mgmt *assoc;
 252         u16 seq;
 253
 254         if (iapp == NULL)
 255                 return;
 256
 257         assoc = sta->last_assoc_req;
 258         seq = assoc ? WLAN_GET_SEQ_SEQ(le_to_host16(assoc->seq_ctrl)) : 0;
 259
 260         /* IAPP-ADD.request(MAC Address, Sequence Number, Timeout) */
 261         hostapd_logger(iapp->hapd, sta->addr, HOSTAPD_MODULE_IAPP,
 262                        HOSTAPD_LEVEL_DEBUG, "IAPP-ADD.request(seq=%d)", seq);
 263         iapp_send_layer2_update(iapp, sta->addr);
 264         iapp_send_add(iapp, sta->addr, seq);
 265
 266         if (assoc && WLAN_FC_GET_STYPE(le_to_host16(assoc->frame_control)) ==
 267             WLAN_FC_STYPE_REASSOC_REQ) {
 268                 /* IAPP-MOVE.request(MAC Address, Sequence Number, Old AP,
 269                  *                   Context Block, Timeout)
 270                  */
 271                 /* TODO: Send IAPP-MOVE to the old AP; Map Old AP BSSID to
 272                  * IP address */
 273         }
 274 }
 275
 276
 277 static void iapp_process_add_notify(struct iapp_data *iapp,
 278                                     struct sockaddr_in *from,
 279                                     struct iapp_hdr *hdr, int len)
 280 {
 281         struct iapp_add_notify *add = (struct iapp_add_notify *) (hdr + 1);
 282         struct sta_info *sta;
 283
 284         if (len != sizeof(*add)) {
 285                 printf("Invalid IAPP-ADD packet length %d (expected %lu)\n",
 286                        len, (unsigned long) sizeof(*add));
 287                 return;
 288         }
 289
 290         sta = ap_get_sta(iapp->hapd, add->mac_addr);
 291
 292         /* IAPP-ADD.indication(MAC Address, Sequence Number) */
 293         hostapd_logger(iapp->hapd, add->mac_addr, HOSTAPD_MODULE_IAPP,
 294                        HOSTAPD_LEVEL_INFO,
 295                        "Received IAPP ADD-notify (seq# %d) from %s:%d%s",
 296                        be_to_host16(add->seq_num),
 297                        inet_ntoa(from->sin_addr), ntohs(from->sin_port),
 298                        sta ? "" : " (STA not found)");
 299
 300         if (!sta)
 301                 return;
 302
 303         /* TODO: could use seq_num to try to determine whether last association
 304          * to this AP is newer than the one advertised in IAPP-ADD. Although,
 305          * this is not really a reliable verification. */
 306
 307         hostapd_logger(iapp->hapd, add->mac_addr, HOSTAPD_MODULE_IAPP,
 308                        HOSTAPD_LEVEL_DEBUG,
 309                        "Removing STA due to IAPP ADD-notify");
 310         ap_sta_disconnect(iapp->hapd, sta, NULL, 0);
 311 }
 312
 313
 314 /**
 315  * iapp_receive_udp - Process IAPP UDP frames
 316  * @sock: File descriptor for the socket
 317  * @eloop_ctx: IAPP data (struct iapp_data *)
 318  * @sock_ctx: Not used
 319  */
 320 static void iapp_receive_udp(int sock, void *eloop_ctx, void *sock_ctx)
 321 {
 322         struct iapp_data *iapp = eloop_ctx;
 323         int len, hlen;
 324         unsigned char buf[128];
 325         struct sockaddr_in from;
 326         socklen_t fromlen;
 327         struct iapp_hdr *hdr;
 328
 329         /* Handle incoming IAPP frames (over UDP/IP) */
 330
 331         fromlen = sizeof(from);
 332         len = recvfrom(iapp->udp_sock, buf, sizeof(buf), 0,
 333                        (struct sockaddr *) &from, &fromlen);
 334         if (len < 0) {
 335                 perror("recvfrom");
 336                 return;
 337         }
 338
 339         if (from.sin_addr.s_addr == iapp->own.s_addr)
 340                 return; /* ignore own IAPP messages */
 341
 342         hostapd_logger(iapp->hapd, NULL, HOSTAPD_MODULE_IAPP,
 343                        HOSTAPD_LEVEL_DEBUG,
 344                        "Received %d byte IAPP frame from %s%s\n",
 345                        len, inet_ntoa(from.sin_addr),
 346                        len < (int) sizeof(*hdr) ? " (too short)" : "");
 347
 348         if (len < (int) sizeof(*hdr))
 349                 return;
 350
 351         hdr = (struct iapp_hdr *) buf;
 352         hlen = be_to_host16(hdr->length);
 353         hostapd_logger(iapp->hapd, NULL, HOSTAPD_MODULE_IAPP,
 354                        HOSTAPD_LEVEL_DEBUG,
 355                        "RX: version=%d command=%d id=%d len=%d\n",
 356                        hdr->version, hdr->command,
 357                        be_to_host16(hdr->identifier), hlen);
 358         if (hdr->version != IAPP_VERSION) {
 359                 printf("Dropping IAPP frame with unknown version %d\n",
 360                        hdr->version);
 361                 return;
 362         }
 363         if (hlen > len) {
 364                 printf("Underflow IAPP frame (hlen=%d len=%d)\n", hlen, len);
 365                 return;
 366         }
 367         if (hlen < len) {
 368                 printf("Ignoring %d extra bytes from IAPP frame\n",
 369                        len - hlen);
 370                 len = hlen;
 371         }
 372
 373         switch (hdr->command) {
 374         case IAPP_CMD_ADD_notify:
 375                 iapp_process_add_notify(iapp, &from, hdr, hlen - sizeof(*hdr));
 376                 break;
 377         case IAPP_CMD_MOVE_notify:
 378                 /* TODO: MOVE is using TCP; so move this to TCP handler once it
 379                  * is implemented.. */
 380                 /* IAPP-MOVE.indication(MAC Address, New BSSID,
 381                  * Sequence Number, AP Address, Context Block) */
 382                 /* TODO: process */
 383                 break;
 384         default:
 385                 printf("Unknown IAPP command %d\n", hdr->command);
 386                 break;
 387         }
 388 }
 389
 390
 391 struct iapp_data * iapp_init(struct hostapd_data *hapd, const char *iface)
 392 {
 393         struct ifreq ifr;
 394         struct sockaddr_ll addr;
 395         int ifindex;
 396         struct sockaddr_in *paddr, uaddr;
 397         struct iapp_data *iapp;
 398         struct ip_mreqn mreq;
 399
 400         iapp = os_zalloc(sizeof(*iapp));
 401         if (iapp == NULL)
 402                 return NULL;
 403         iapp->hapd = hapd;
 404         iapp->udp_sock = iapp->packet_sock = -1;
 405
 406         /* TODO:
 407          * open socket for sending and receiving IAPP frames over TCP
 408          */
 409
 410         iapp->udp_sock = socket(PF_INET, SOCK_DGRAM, 0);
 411         if (iapp->udp_sock < 0) {
 412                 perror("socket[PF_INET,SOCK_DGRAM]");
 413                 iapp_deinit(iapp);
 414                 return NULL;
 415         }
 416
 417         os_memset(&ifr, 0, sizeof(ifr));
 418         os_strlcpy(ifr.ifr_name, iface, sizeof(ifr.ifr_name));
 419         if (ioctl(iapp->udp_sock, SIOCGIFINDEX, &ifr) != 0) {
 420                 perror("ioctl(SIOCGIFINDEX)");
 421                 iapp_deinit(iapp);
 422                 return NULL;
 423         }
 424         ifindex = ifr.ifr_ifindex;
 425
 426         if (ioctl(iapp->udp_sock, SIOCGIFADDR, &ifr) != 0) {
 427                 perror("ioctl(SIOCGIFADDR)");
 428                 iapp_deinit(iapp);
 429                 return NULL;
 430         }
 431         paddr = (struct sockaddr_in *) &ifr.ifr_addr;
 432         if (paddr->sin_family != AF_INET) {
 433                 printf("Invalid address family %i (SIOCGIFADDR)\n",
 434                        paddr->sin_family);
 435                 iapp_deinit(iapp);
 436                 return NULL;
 437         }
 438         iapp->own.s_addr = paddr->sin_addr.s_addr;
 439
 440         if (ioctl(iapp->udp_sock, SIOCGIFBRDADDR, &ifr) != 0) {
 441                 perror("ioctl(SIOCGIFBRDADDR)");
 442                 iapp_deinit(iapp);
 443                 return NULL;
 444         }
 445         paddr = (struct sockaddr_in *) &ifr.ifr_addr;
 446         if (paddr->sin_family != AF_INET) {
 447                 printf("Invalid address family %i (SIOCGIFBRDADDR)\n",
 448                        paddr->sin_family);
 449                 iapp_deinit(iapp);
 450                 return NULL;
 451         }
 452         inet_aton(IAPP_MULTICAST, &iapp->multicast);
 453
 454         os_memset(&uaddr, 0, sizeof(uaddr));
 455         uaddr.sin_family = AF_INET;
 456         uaddr.sin_port = htons(IAPP_UDP_PORT);
 457         if (bind(iapp->udp_sock, (struct sockaddr *) &uaddr,
 458                  sizeof(uaddr)) < 0) {
 459                 perror("bind[UDP]");
 460                 iapp_deinit(iapp);
 461                 return NULL;
 462         }
 463
 464         os_memset(&mreq, 0, sizeof(mreq));
 465         mreq.imr_multiaddr = iapp->multicast;
 466         mreq.imr_address.s_addr = INADDR_ANY;
 467         mreq.imr_ifindex = 0;
 468         if (setsockopt(iapp->udp_sock, SOL_IP, IP_ADD_MEMBERSHIP, &mreq,
 469                        sizeof(mreq)) < 0) {
 470                 perror("setsockopt[UDP,IP_ADD_MEMBERSHIP]");
 471                 iapp_deinit(iapp);
 472                 return NULL;
 473         }
 474
 475         iapp->packet_sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
 476         if (iapp->packet_sock < 0) {
 477                 perror("socket[PF_PACKET,SOCK_RAW]");
 478                 iapp_deinit(iapp);
 479                 return NULL;
 480         }
 481
 482         os_memset(&addr, 0, sizeof(addr));
 483         addr.sll_family = AF_PACKET;
 484         addr.sll_ifindex = ifindex;
 485         if (bind(iapp->packet_sock, (struct sockaddr *) &addr,
 486                  sizeof(addr)) < 0) {
 487                 perror("bind[PACKET]");
 488                 iapp_deinit(iapp);
 489                 return NULL;
 490         }
 491
 492         if (eloop_register_read_sock(iapp->udp_sock, iapp_receive_udp,
 493                                      iapp, NULL)) {
 494                 printf("Could not register read socket for IAPP.\n");
 495                 iapp_deinit(iapp);
 496                 return NULL;
 497         }
 498
 499         printf("IEEE 802.11F (IAPP) using interface %s\n", iface);
 500
 501         /* TODO: For levels 2 and 3: send RADIUS Initiate-Request, receive
 502          * RADIUS Initiate-Accept or Initiate-Reject. IAPP port should actually
 503          * be openned only after receiving Initiate-Accept. If Initiate-Reject
 504          * is received, IAPP is not started. */
 505
 506         return iapp;
 507 }
 508
 509
 510 void iapp_deinit(struct iapp_data *iapp)
 511 {
 512         struct ip_mreqn mreq;
 513
 514         if (iapp == NULL)
 515                 return;
 516
 517         if (iapp->udp_sock >= 0) {
 518                 os_memset(&mreq, 0, sizeof(mreq));
 519                 mreq.imr_multiaddr = iapp->multicast;
 520                 mreq.imr_address.s_addr = INADDR_ANY;
 521                 mreq.imr_ifindex = 0;
 522                 if (setsockopt(iapp->udp_sock, SOL_IP, IP_DROP_MEMBERSHIP,
 523                                &mreq, sizeof(mreq)) < 0) {
 524                         perror("setsockopt[UDP,IP_DEL_MEMBERSHIP]");
 525                 }
 526
 527                 eloop_unregister_read_sock(iapp->udp_sock);
 528                 close(iapp->udp_sock);
 529         }
 530         if (iapp->packet_sock >= 0) {
 531                 eloop_unregister_read_sock(iapp->packet_sock);
 532                 close(iapp->packet_sock);
 533         }
 534         os_free(iapp);
 535 }