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 
handle_tx_callback(void * ctx,u8 * buf,size_t len,int ok)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 
from_unknown_sta(struct wpa_driver_nl80211_data * drv,u8 * buf,size_t len)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 
handle_frame(struct wpa_driver_nl80211_data * drv,u8 * buf,size_t len,int datarate,int ssi_signal)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 
handle_monitor_read(int sock,void * eloop_ctx,void * sock_ctx)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 
add_monitor_filter(int s)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 
nl80211_remove_monitor_interface(struct wpa_driver_nl80211_data * drv)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 
nl80211_create_monitor_interface(struct wpa_driver_nl80211_data * drv)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 
nl80211_send_monitor(struct wpa_driver_nl80211_data * drv,const void * data,size_t len,int encrypt,int noack)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