1 /* 2 * Driver interaction with Linux nl80211/cfg80211 - AP monitor interface 3 * Copyright (c) 2002-2014, Jouni Malinen <j@w1.fi> 4 * Copyright (c) 2003-2004, Instant802 Networks, Inc. 5 * Copyright (c) 2005-2006, Devicescape Software, Inc. 6 * Copyright (c) 2007, Johannes Berg <johannes@sipsolutions.net> 7 * Copyright (c) 2009-2010, Atheros Communications 8 * 9 * This software may be distributed under the terms of the BSD license. 10 * See README for more details. 11 */ 12 13 #include "includes.h" 14 #include <netpacket/packet.h> 15 #include <linux/filter.h> 16 17 #include "utils/common.h" 18 #include "utils/eloop.h" 19 #include "common/ieee802_11_defs.h" 20 #include "common/ieee802_11_common.h" 21 #include "linux_ioctl.h" 22 #include "radiotap_iter.h" 23 #include "driver_nl80211.h" 24 25 26 static void handle_tx_callback(void *ctx, u8 *buf, size_t len, int ok) 27 { 28 struct ieee80211_hdr *hdr; 29 u16 fc; 30 union wpa_event_data event; 31 32 hdr = (struct ieee80211_hdr *) buf; 33 fc = le_to_host16(hdr->frame_control); 34 35 os_memset(&event, 0, sizeof(event)); 36 event.tx_status.type = WLAN_FC_GET_TYPE(fc); 37 event.tx_status.stype = WLAN_FC_GET_STYPE(fc); 38 event.tx_status.dst = hdr->addr1; 39 event.tx_status.data = buf; 40 event.tx_status.data_len = len; 41 event.tx_status.ack = ok; 42 wpa_supplicant_event(ctx, EVENT_TX_STATUS, &event); 43 } 44 45 46 static void from_unknown_sta(struct wpa_driver_nl80211_data *drv, 47 u8 *buf, size_t len) 48 { 49 struct ieee80211_hdr *hdr = (void *)buf; 50 u16 fc; 51 union wpa_event_data event; 52 53 if (len < sizeof(*hdr)) 54 return; 55 56 fc = le_to_host16(hdr->frame_control); 57 58 os_memset(&event, 0, sizeof(event)); 59 event.rx_from_unknown.bssid = get_hdr_bssid(hdr, len); 60 event.rx_from_unknown.addr = hdr->addr2; 61 event.rx_from_unknown.wds = (fc & (WLAN_FC_FROMDS | WLAN_FC_TODS)) == 62 (WLAN_FC_FROMDS | WLAN_FC_TODS); 63 wpa_supplicant_event(drv->ctx, EVENT_RX_FROM_UNKNOWN, &event); 64 } 65 66 67 static void handle_frame(struct wpa_driver_nl80211_data *drv, 68 u8 *buf, size_t len, int datarate, int ssi_signal) 69 { 70 struct ieee80211_hdr *hdr; 71 u16 fc; 72 union wpa_event_data event; 73 74 hdr = (struct ieee80211_hdr *) buf; 75 fc = le_to_host16(hdr->frame_control); 76 77 switch (WLAN_FC_GET_TYPE(fc)) { 78 case WLAN_FC_TYPE_MGMT: 79 os_memset(&event, 0, sizeof(event)); 80 event.rx_mgmt.frame = buf; 81 event.rx_mgmt.frame_len = len; 82 event.rx_mgmt.datarate = datarate; 83 event.rx_mgmt.ssi_signal = ssi_signal; 84 wpa_supplicant_event(drv->ctx, EVENT_RX_MGMT, &event); 85 break; 86 case WLAN_FC_TYPE_CTRL: 87 /* can only get here with PS-Poll frames */ 88 wpa_printf(MSG_DEBUG, "CTRL"); 89 from_unknown_sta(drv, buf, len); 90 break; 91 case WLAN_FC_TYPE_DATA: 92 from_unknown_sta(drv, buf, len); 93 break; 94 } 95 } 96 97 98 static void handle_monitor_read(int sock, void *eloop_ctx, void *sock_ctx) 99 { 100 struct wpa_driver_nl80211_data *drv = eloop_ctx; 101 int len; 102 unsigned char buf[3000]; 103 struct ieee80211_radiotap_iterator iter; 104 int ret; 105 int datarate = 0, ssi_signal = 0; 106 int injected = 0, failed = 0, rxflags = 0; 107 108 len = recv(sock, buf, sizeof(buf), 0); 109 if (len < 0) { 110 wpa_printf(MSG_ERROR, "nl80211: Monitor socket recv failed: %s", 111 strerror(errno)); 112 return; 113 } 114 115 if (ieee80211_radiotap_iterator_init(&iter, (void *) buf, len, NULL)) { 116 wpa_printf(MSG_INFO, "nl80211: received invalid radiotap frame"); 117 return; 118 } 119 120 while (1) { 121 ret = ieee80211_radiotap_iterator_next(&iter); 122 if (ret == -ENOENT) 123 break; 124 if (ret) { 125 wpa_printf(MSG_INFO, "nl80211: received invalid radiotap frame (%d)", 126 ret); 127 return; 128 } 129 switch (iter.this_arg_index) { 130 case IEEE80211_RADIOTAP_FLAGS: 131 if (*iter.this_arg & IEEE80211_RADIOTAP_F_FCS) 132 len -= 4; 133 break; 134 case IEEE80211_RADIOTAP_RX_FLAGS: 135 rxflags = 1; 136 break; 137 case IEEE80211_RADIOTAP_TX_FLAGS: 138 injected = 1; 139 failed = le_to_host16((*(le16 *) iter.this_arg)) & 140 IEEE80211_RADIOTAP_F_TX_FAIL; 141 break; 142 case IEEE80211_RADIOTAP_DATA_RETRIES: 143 break; 144 case IEEE80211_RADIOTAP_CHANNEL: 145 /* TODO: convert from freq/flags to channel number */ 146 break; 147 case IEEE80211_RADIOTAP_RATE: 148 datarate = *iter.this_arg * 5; 149 break; 150 case IEEE80211_RADIOTAP_DBM_ANTSIGNAL: 151 ssi_signal = (s8) *iter.this_arg; 152 break; 153 } 154 } 155 156 if (rxflags && injected) 157 return; 158 159 if (!injected) 160 handle_frame(drv, buf + iter._max_length, 161 len - iter._max_length, datarate, ssi_signal); 162 else 163 handle_tx_callback(drv->ctx, buf + iter._max_length, 164 len - iter._max_length, !failed); 165 } 166 167 168 /* 169 * we post-process the filter code later and rewrite 170 * this to the offset to the last instruction 171 */ 172 #define PASS 0xFF 173 #define FAIL 0xFE 174 175 static struct sock_filter msock_filter_insns[] = { 176 /* 177 * do a little-endian load of the radiotap length field 178 */ 179 /* load lower byte into A */ 180 BPF_STMT(BPF_LD | BPF_B | BPF_ABS, 2), 181 /* put it into X (== index register) */ 182 BPF_STMT(BPF_MISC| BPF_TAX, 0), 183 /* load upper byte into A */ 184 BPF_STMT(BPF_LD | BPF_B | BPF_ABS, 3), 185 /* left-shift it by 8 */ 186 BPF_STMT(BPF_ALU | BPF_LSH | BPF_K, 8), 187 /* or with X */ 188 BPF_STMT(BPF_ALU | BPF_OR | BPF_X, 0), 189 /* put result into X */ 190 BPF_STMT(BPF_MISC| BPF_TAX, 0), 191 192 /* 193 * Allow management frames through, this also gives us those 194 * management frames that we sent ourselves with status 195 */ 196 /* load the lower byte of the IEEE 802.11 frame control field */ 197 BPF_STMT(BPF_LD | BPF_B | BPF_IND, 0), 198 /* mask off frame type and version */ 199 BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0xF), 200 /* accept frame if it's both 0, fall through otherwise */ 201 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0, PASS, 0), 202 203 /* 204 * TODO: add a bit to radiotap RX flags that indicates 205 * that the sending station is not associated, then 206 * add a filter here that filters on our DA and that flag 207 * to allow us to deauth frames to that bad station. 208 * 209 * For now allow all To DS data frames through. 210 */ 211 /* load the IEEE 802.11 frame control field */ 212 BPF_STMT(BPF_LD | BPF_H | BPF_IND, 0), 213 /* mask off frame type, version and DS status */ 214 BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0x0F03), 215 /* accept frame if version 0, type 2 and To DS, fall through otherwise 216 */ 217 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0x0801, PASS, 0), 218 219 #if 0 220 /* 221 * drop non-data frames 222 */ 223 /* load the lower byte of the frame control field */ 224 BPF_STMT(BPF_LD | BPF_B | BPF_IND, 0), 225 /* mask off QoS bit */ 226 BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0x0c), 227 /* drop non-data frames */ 228 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 8, 0, FAIL), 229 #endif 230 /* load the upper byte of the frame control field */ 231 BPF_STMT(BPF_LD | BPF_B | BPF_IND, 1), 232 /* mask off toDS/fromDS */ 233 BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0x03), 234 /* accept WDS frames */ 235 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 3, PASS, 0), 236 237 /* 238 * add header length to index 239 */ 240 /* load the lower byte of the frame control field */ 241 BPF_STMT(BPF_LD | BPF_B | BPF_IND, 0), 242 /* mask off QoS bit */ 243 BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0x80), 244 /* right shift it by 6 to give 0 or 2 */ 245 BPF_STMT(BPF_ALU | BPF_RSH | BPF_K, 6), 246 /* add data frame header length */ 247 BPF_STMT(BPF_ALU | BPF_ADD | BPF_K, 24), 248 /* add index, was start of 802.11 header */ 249 BPF_STMT(BPF_ALU | BPF_ADD | BPF_X, 0), 250 /* move to index, now start of LL header */ 251 BPF_STMT(BPF_MISC | BPF_TAX, 0), 252 253 /* 254 * Accept empty data frames, we use those for 255 * polling activity. 256 */ 257 BPF_STMT(BPF_LD | BPF_W | BPF_LEN, 0), 258 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_X, 0, PASS, 0), 259 260 /* 261 * Accept EAPOL frames 262 */ 263 BPF_STMT(BPF_LD | BPF_W | BPF_IND, 0), 264 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0xAAAA0300, 0, FAIL), 265 BPF_STMT(BPF_LD | BPF_W | BPF_IND, 4), 266 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0x0000888E, PASS, FAIL), 267 268 /* keep these last two statements or change the code below */ 269 /* return 0 == "DROP" */ 270 BPF_STMT(BPF_RET | BPF_K, 0), 271 /* return ~0 == "keep all" */ 272 BPF_STMT(BPF_RET | BPF_K, ~0), 273 }; 274 275 static struct sock_fprog msock_filter = { 276 .len = ARRAY_SIZE(msock_filter_insns), 277 .filter = msock_filter_insns, 278 }; 279 280 281 static int add_monitor_filter(int s) 282 { 283 int idx; 284 285 /* rewrite all PASS/FAIL jump offsets */ 286 for (idx = 0; idx < msock_filter.len; idx++) { 287 struct sock_filter *insn = &msock_filter_insns[idx]; 288 289 if (BPF_CLASS(insn->code) == BPF_JMP) { 290 if (insn->code == (BPF_JMP|BPF_JA)) { 291 if (insn->k == PASS) 292 insn->k = msock_filter.len - idx - 2; 293 else if (insn->k == FAIL) 294 insn->k = msock_filter.len - idx - 3; 295 } 296 297 if (insn->jt == PASS) 298 insn->jt = msock_filter.len - idx - 2; 299 else if (insn->jt == FAIL) 300 insn->jt = msock_filter.len - idx - 3; 301 302 if (insn->jf == PASS) 303 insn->jf = msock_filter.len - idx - 2; 304 else if (insn->jf == FAIL) 305 insn->jf = msock_filter.len - idx - 3; 306 } 307 } 308 309 if (setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, 310 &msock_filter, sizeof(msock_filter))) { 311 wpa_printf(MSG_ERROR, "nl80211: setsockopt(SO_ATTACH_FILTER) failed: %s", 312 strerror(errno)); 313 return -1; 314 } 315 316 return 0; 317 } 318 319 320 void nl80211_remove_monitor_interface(struct wpa_driver_nl80211_data *drv) 321 { 322 if (drv->monitor_refcount > 0) 323 drv->monitor_refcount--; 324 wpa_printf(MSG_DEBUG, "nl80211: Remove monitor interface: refcount=%d", 325 drv->monitor_refcount); 326 if (drv->monitor_refcount > 0) 327 return; 328 329 if (drv->monitor_ifidx >= 0) { 330 nl80211_remove_iface(drv, drv->monitor_ifidx); 331 drv->monitor_ifidx = -1; 332 } 333 if (drv->monitor_sock >= 0) { 334 eloop_unregister_read_sock(drv->monitor_sock); 335 close(drv->monitor_sock); 336 drv->monitor_sock = -1; 337 } 338 } 339 340 341 int nl80211_create_monitor_interface(struct wpa_driver_nl80211_data *drv) 342 { 343 char buf[IFNAMSIZ]; 344 struct sockaddr_ll ll; 345 int optval; 346 socklen_t optlen; 347 348 if (drv->monitor_ifidx >= 0) { 349 drv->monitor_refcount++; 350 wpa_printf(MSG_DEBUG, "nl80211: Re-use existing monitor interface: refcount=%d", 351 drv->monitor_refcount); 352 return 0; 353 } 354 355 if (os_strncmp(drv->first_bss->ifname, "p2p-", 4) == 0) { 356 /* 357 * P2P interface name is of the format p2p-%s-%d. For monitor 358 * interface name corresponding to P2P GO, replace "p2p-" with 359 * "mon-" to retain the same interface name length and to 360 * indicate that it is a monitor interface. 361 */ 362 snprintf(buf, IFNAMSIZ, "mon-%s", drv->first_bss->ifname + 4); 363 } else { 364 int ret; 365 366 /* Non-P2P interface with AP functionality. */ 367 ret = os_snprintf(buf, IFNAMSIZ, "mon.%s", 368 drv->first_bss->ifname); 369 if (ret >= (int) sizeof(buf)) 370 wpa_printf(MSG_DEBUG, 371 "nl80211: Monitor interface name has been truncated to %s", 372 buf); 373 else if (ret < 0) 374 return ret; 375 } 376 377 buf[IFNAMSIZ - 1] = '\0'; 378 379 drv->monitor_ifidx = 380 nl80211_create_iface(drv, buf, NL80211_IFTYPE_MONITOR, NULL, 381 0, NULL, NULL, 0); 382 383 if (drv->monitor_ifidx == -EOPNOTSUPP) { 384 /* 385 * This is backward compatibility for a few versions of 386 * the kernel only that didn't advertise the right 387 * attributes for the only driver that then supported 388 * AP mode w/o monitor -- ath6kl. 389 */ 390 wpa_printf(MSG_DEBUG, "nl80211: Driver does not support " 391 "monitor interface type - try to run without it"); 392 drv->device_ap_sme = 1; 393 } 394 395 if (drv->monitor_ifidx < 0) 396 return -1; 397 398 if (linux_set_iface_flags(drv->global->ioctl_sock, buf, 1)) 399 goto error; 400 401 memset(&ll, 0, sizeof(ll)); 402 ll.sll_family = AF_PACKET; 403 ll.sll_ifindex = drv->monitor_ifidx; 404 drv->monitor_sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL)); 405 if (drv->monitor_sock < 0) { 406 wpa_printf(MSG_ERROR, "nl80211: socket[PF_PACKET,SOCK_RAW] failed: %s", 407 strerror(errno)); 408 goto error; 409 } 410 411 if (add_monitor_filter(drv->monitor_sock)) { 412 wpa_printf(MSG_INFO, "Failed to set socket filter for monitor " 413 "interface; do filtering in user space"); 414 /* This works, but will cost in performance. */ 415 } 416 417 if (bind(drv->monitor_sock, (struct sockaddr *) &ll, sizeof(ll)) < 0) { 418 wpa_printf(MSG_ERROR, "nl80211: monitor socket bind failed: %s", 419 strerror(errno)); 420 goto error; 421 } 422 423 optlen = sizeof(optval); 424 optval = 20; 425 if (setsockopt 426 (drv->monitor_sock, SOL_SOCKET, SO_PRIORITY, &optval, optlen)) { 427 wpa_printf(MSG_ERROR, "nl80211: Failed to set socket priority: %s", 428 strerror(errno)); 429 goto error; 430 } 431 432 if (eloop_register_read_sock(drv->monitor_sock, handle_monitor_read, 433 drv, NULL)) { 434 wpa_printf(MSG_INFO, "nl80211: Could not register monitor read socket"); 435 goto error; 436 } 437 438 drv->monitor_refcount++; 439 return 0; 440 error: 441 nl80211_remove_monitor_interface(drv); 442 return -1; 443 } 444 445 446 int nl80211_send_monitor(struct wpa_driver_nl80211_data *drv, 447 const void *data, size_t len, 448 int encrypt, int noack) 449 { 450 __u8 rtap_hdr[] = { 451 0x00, 0x00, /* radiotap version */ 452 0x0e, 0x00, /* radiotap length */ 453 0x02, 0xc0, 0x00, 0x00, /* bmap: flags, tx and rx flags */ 454 IEEE80211_RADIOTAP_F_FRAG, /* F_FRAG (fragment if required) */ 455 0x00, /* padding */ 456 0x00, 0x00, /* RX and TX flags to indicate that */ 457 0x00, 0x00, /* this is the injected frame directly */ 458 }; 459 struct iovec iov[2] = { 460 { 461 .iov_base = &rtap_hdr, 462 .iov_len = sizeof(rtap_hdr), 463 }, 464 { 465 .iov_base = (void *) data, 466 .iov_len = len, 467 } 468 }; 469 struct msghdr msg = { 470 .msg_name = NULL, 471 .msg_namelen = 0, 472 .msg_iov = iov, 473 .msg_iovlen = 2, 474 .msg_control = NULL, 475 .msg_controllen = 0, 476 .msg_flags = 0, 477 }; 478 int res; 479 u16 txflags = 0; 480 481 if (encrypt) 482 rtap_hdr[8] |= IEEE80211_RADIOTAP_F_WEP; 483 484 if (drv->monitor_sock < 0) { 485 wpa_printf(MSG_DEBUG, "nl80211: No monitor socket available " 486 "for %s", __func__); 487 return -1; 488 } 489 490 if (noack) 491 txflags |= IEEE80211_RADIOTAP_F_TX_NOACK; 492 WPA_PUT_LE16(&rtap_hdr[12], txflags); 493 494 res = sendmsg(drv->monitor_sock, &msg, 0); 495 if (res < 0) { 496 wpa_printf(MSG_INFO, "nl80211: sendmsg: %s", strerror(errno)); 497 return -1; 498 } 499 return 0; 500 } 501