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 if (!drv->use_monitor)
75 return;
76
77 hdr = (struct ieee80211_hdr *) buf;
78 fc = le_to_host16(hdr->frame_control);
79
80 switch (WLAN_FC_GET_TYPE(fc)) {
81 case WLAN_FC_TYPE_MGMT:
82 os_memset(&event, 0, sizeof(event));
83 event.rx_mgmt.frame = buf;
84 event.rx_mgmt.frame_len = len;
85 event.rx_mgmt.datarate = datarate;
86 event.rx_mgmt.ssi_signal = ssi_signal;
87 wpa_supplicant_event(drv->ctx, EVENT_RX_MGMT, &event);
88 break;
89 case WLAN_FC_TYPE_CTRL:
90 /* can only get here with PS-Poll frames */
91 wpa_printf(MSG_DEBUG, "CTRL");
92 from_unknown_sta(drv, buf, len);
93 break;
94 case WLAN_FC_TYPE_DATA:
95 from_unknown_sta(drv, buf, len);
96 break;
97 }
98 }
99
100
handle_monitor_read(int sock,void * eloop_ctx,void * sock_ctx)101 static void handle_monitor_read(int sock, void *eloop_ctx, void *sock_ctx)
102 {
103 struct wpa_driver_nl80211_data *drv = eloop_ctx;
104 int len;
105 unsigned char buf[3000];
106 struct ieee80211_radiotap_iterator iter;
107 int ret;
108 int datarate = 0, ssi_signal = 0;
109 int injected = 0, failed = 0, rxflags = 0;
110
111 len = recv(sock, buf, sizeof(buf), 0);
112 if (len < 0) {
113 wpa_printf(MSG_ERROR, "nl80211: Monitor socket recv failed: %s",
114 strerror(errno));
115 return;
116 }
117
118 if (ieee80211_radiotap_iterator_init(&iter, (void *) buf, len, NULL)) {
119 wpa_printf(MSG_INFO, "nl80211: received invalid radiotap frame");
120 return;
121 }
122
123 while (1) {
124 ret = ieee80211_radiotap_iterator_next(&iter);
125 if (ret == -ENOENT)
126 break;
127 if (ret) {
128 wpa_printf(MSG_INFO, "nl80211: received invalid radiotap frame (%d)",
129 ret);
130 return;
131 }
132 switch (iter.this_arg_index) {
133 case IEEE80211_RADIOTAP_FLAGS:
134 if (*iter.this_arg & IEEE80211_RADIOTAP_F_FCS)
135 len -= 4;
136 break;
137 case IEEE80211_RADIOTAP_RX_FLAGS:
138 rxflags = 1;
139 break;
140 case IEEE80211_RADIOTAP_TX_FLAGS:
141 injected = 1;
142 failed = le_to_host16((*(le16 *) iter.this_arg)) &
143 IEEE80211_RADIOTAP_F_TX_FAIL;
144 break;
145 case IEEE80211_RADIOTAP_DATA_RETRIES:
146 break;
147 case IEEE80211_RADIOTAP_CHANNEL:
148 /* TODO: convert from freq/flags to channel number */
149 break;
150 case IEEE80211_RADIOTAP_RATE:
151 datarate = *iter.this_arg * 5;
152 break;
153 case IEEE80211_RADIOTAP_DBM_ANTSIGNAL:
154 ssi_signal = (s8) *iter.this_arg;
155 break;
156 }
157 }
158
159 if (rxflags && injected)
160 return;
161
162 if (!injected)
163 handle_frame(drv, buf + iter._max_length,
164 len - iter._max_length, datarate, ssi_signal);
165 else
166 handle_tx_callback(drv->ctx, buf + iter._max_length,
167 len - iter._max_length, !failed);
168 }
169
170
171 /*
172 * we post-process the filter code later and rewrite
173 * this to the offset to the last instruction
174 */
175 #define PASS 0xFF
176 #define FAIL 0xFE
177
178 static struct sock_filter msock_filter_insns[] = {
179 /*
180 * do a little-endian load of the radiotap length field
181 */
182 /* load lower byte into A */
183 BPF_STMT(BPF_LD | BPF_B | BPF_ABS, 2),
184 /* put it into X (== index register) */
185 BPF_STMT(BPF_MISC| BPF_TAX, 0),
186 /* load upper byte into A */
187 BPF_STMT(BPF_LD | BPF_B | BPF_ABS, 3),
188 /* left-shift it by 8 */
189 BPF_STMT(BPF_ALU | BPF_LSH | BPF_K, 8),
190 /* or with X */
191 BPF_STMT(BPF_ALU | BPF_OR | BPF_X, 0),
192 /* put result into X */
193 BPF_STMT(BPF_MISC| BPF_TAX, 0),
194
195 /*
196 * Allow management frames through, this also gives us those
197 * management frames that we sent ourselves with status
198 */
199 /* load the lower byte of the IEEE 802.11 frame control field */
200 BPF_STMT(BPF_LD | BPF_B | BPF_IND, 0),
201 /* mask off frame type and version */
202 BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0xF),
203 /* accept frame if it's both 0, fall through otherwise */
204 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0, PASS, 0),
205
206 /*
207 * TODO: add a bit to radiotap RX flags that indicates
208 * that the sending station is not associated, then
209 * add a filter here that filters on our DA and that flag
210 * to allow us to deauth frames to that bad station.
211 *
212 * For now allow all To DS data frames through.
213 */
214 /* load the IEEE 802.11 frame control field */
215 BPF_STMT(BPF_LD | BPF_H | BPF_IND, 0),
216 /* mask off frame type, version and DS status */
217 BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0x0F03),
218 /* accept frame if version 0, type 2 and To DS, fall through otherwise
219 */
220 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0x0801, PASS, 0),
221
222 #if 0
223 /*
224 * drop non-data frames
225 */
226 /* load the lower byte of the frame control field */
227 BPF_STMT(BPF_LD | BPF_B | BPF_IND, 0),
228 /* mask off QoS bit */
229 BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0x0c),
230 /* drop non-data frames */
231 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 8, 0, FAIL),
232 #endif
233 /* load the upper byte of the frame control field */
234 BPF_STMT(BPF_LD | BPF_B | BPF_IND, 1),
235 /* mask off toDS/fromDS */
236 BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0x03),
237 /* accept WDS frames */
238 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 3, PASS, 0),
239
240 /*
241 * add header length to index
242 */
243 /* load the lower byte of the frame control field */
244 BPF_STMT(BPF_LD | BPF_B | BPF_IND, 0),
245 /* mask off QoS bit */
246 BPF_STMT(BPF_ALU | BPF_AND | BPF_K, 0x80),
247 /* right shift it by 6 to give 0 or 2 */
248 BPF_STMT(BPF_ALU | BPF_RSH | BPF_K, 6),
249 /* add data frame header length */
250 BPF_STMT(BPF_ALU | BPF_ADD | BPF_K, 24),
251 /* add index, was start of 802.11 header */
252 BPF_STMT(BPF_ALU | BPF_ADD | BPF_X, 0),
253 /* move to index, now start of LL header */
254 BPF_STMT(BPF_MISC | BPF_TAX, 0),
255
256 /*
257 * Accept empty data frames, we use those for
258 * polling activity.
259 */
260 BPF_STMT(BPF_LD | BPF_W | BPF_LEN, 0),
261 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_X, 0, PASS, 0),
262
263 /*
264 * Accept EAPOL frames
265 */
266 BPF_STMT(BPF_LD | BPF_W | BPF_IND, 0),
267 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0xAAAA0300, 0, FAIL),
268 BPF_STMT(BPF_LD | BPF_W | BPF_IND, 4),
269 BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0x0000888E, PASS, FAIL),
270
271 /* keep these last two statements or change the code below */
272 /* return 0 == "DROP" */
273 BPF_STMT(BPF_RET | BPF_K, 0),
274 /* return ~0 == "keep all" */
275 BPF_STMT(BPF_RET | BPF_K, ~0),
276 };
277
278 static struct sock_fprog msock_filter = {
279 .len = ARRAY_SIZE(msock_filter_insns),
280 .filter = msock_filter_insns,
281 };
282
283
add_monitor_filter(int s)284 static int add_monitor_filter(int s)
285 {
286 int idx;
287
288 /* rewrite all PASS/FAIL jump offsets */
289 for (idx = 0; idx < msock_filter.len; idx++) {
290 struct sock_filter *insn = &msock_filter_insns[idx];
291
292 if (BPF_CLASS(insn->code) == BPF_JMP) {
293 if (insn->code == (BPF_JMP|BPF_JA)) {
294 if (insn->k == PASS)
295 insn->k = msock_filter.len - idx - 2;
296 else if (insn->k == FAIL)
297 insn->k = msock_filter.len - idx - 3;
298 }
299
300 if (insn->jt == PASS)
301 insn->jt = msock_filter.len - idx - 2;
302 else if (insn->jt == FAIL)
303 insn->jt = msock_filter.len - idx - 3;
304
305 if (insn->jf == PASS)
306 insn->jf = msock_filter.len - idx - 2;
307 else if (insn->jf == FAIL)
308 insn->jf = msock_filter.len - idx - 3;
309 }
310 }
311
312 if (setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER,
313 &msock_filter, sizeof(msock_filter))) {
314 wpa_printf(MSG_ERROR, "nl80211: setsockopt(SO_ATTACH_FILTER) failed: %s",
315 strerror(errno));
316 return -1;
317 }
318
319 return 0;
320 }
321
322
nl80211_remove_monitor_interface(struct wpa_driver_nl80211_data * drv)323 void nl80211_remove_monitor_interface(struct wpa_driver_nl80211_data *drv)
324 {
325 if (drv->monitor_refcount > 0)
326 drv->monitor_refcount--;
327 wpa_printf(MSG_DEBUG, "nl80211: Remove monitor interface: refcount=%d",
328 drv->monitor_refcount);
329 if (drv->monitor_refcount > 0)
330 return;
331
332 if (drv->monitor_ifidx >= 0) {
333 nl80211_remove_iface(drv, drv->monitor_ifidx);
334 drv->monitor_ifidx = -1;
335 }
336 if (drv->monitor_sock >= 0) {
337 eloop_unregister_read_sock(drv->monitor_sock);
338 close(drv->monitor_sock);
339 drv->monitor_sock = -1;
340 }
341 }
342
343
nl80211_create_monitor_interface(struct wpa_driver_nl80211_data * drv)344 int nl80211_create_monitor_interface(struct wpa_driver_nl80211_data *drv)
345 {
346 char buf[IFNAMSIZ];
347 struct sockaddr_ll ll;
348 int optval;
349 socklen_t optlen;
350
351 if (drv->monitor_ifidx >= 0) {
352 drv->monitor_refcount++;
353 wpa_printf(MSG_DEBUG, "nl80211: Re-use existing monitor interface: refcount=%d",
354 drv->monitor_refcount);
355 return 0;
356 }
357
358 if (os_strncmp(drv->first_bss->ifname, "p2p-", 4) == 0) {
359 /*
360 * P2P interface name is of the format p2p-%s-%d. For monitor
361 * interface name corresponding to P2P GO, replace "p2p-" with
362 * "mon-" to retain the same interface name length and to
363 * indicate that it is a monitor interface.
364 */
365 snprintf(buf, IFNAMSIZ, "mon-%s", drv->first_bss->ifname + 4);
366 } else {
367 int ret;
368
369 /* Non-P2P interface with AP functionality. */
370 ret = os_snprintf(buf, IFNAMSIZ, "mon.%s",
371 drv->first_bss->ifname);
372 if (ret >= (int) sizeof(buf))
373 wpa_printf(MSG_DEBUG,
374 "nl80211: Monitor interface name has been truncated to %s",
375 buf);
376 else if (ret < 0)
377 return ret;
378 }
379
380 buf[IFNAMSIZ - 1] = '\0';
381
382 drv->monitor_ifidx =
383 nl80211_create_iface(drv, buf, NL80211_IFTYPE_MONITOR, NULL,
384 0, NULL, NULL, 0);
385
386 if (drv->monitor_ifidx == -EOPNOTSUPP) {
387 /*
388 * This is backward compatibility for a few versions of
389 * the kernel only that didn't advertise the right
390 * attributes for the only driver that then supported
391 * AP mode w/o monitor -- ath6kl.
392 */
393 wpa_printf(MSG_DEBUG, "nl80211: Driver does not support "
394 "monitor interface type - try to run without it");
395 drv->device_ap_sme = 1;
396 }
397
398 if (drv->monitor_ifidx < 0)
399 return -1;
400
401 if (linux_set_iface_flags(drv->global->ioctl_sock, buf, 1))
402 goto error;
403
404 memset(&ll, 0, sizeof(ll));
405 ll.sll_family = AF_PACKET;
406 ll.sll_ifindex = drv->monitor_ifidx;
407 drv->monitor_sock = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL));
408 if (drv->monitor_sock < 0) {
409 wpa_printf(MSG_ERROR, "nl80211: socket[PF_PACKET,SOCK_RAW] failed: %s",
410 strerror(errno));
411 goto error;
412 }
413
414 if (add_monitor_filter(drv->monitor_sock)) {
415 wpa_printf(MSG_INFO, "Failed to set socket filter for monitor "
416 "interface; do filtering in user space");
417 /* This works, but will cost in performance. */
418 }
419
420 if (bind(drv->monitor_sock, (struct sockaddr *) &ll, sizeof(ll)) < 0) {
421 wpa_printf(MSG_ERROR, "nl80211: monitor socket bind failed: %s",
422 strerror(errno));
423 goto error;
424 }
425
426 optlen = sizeof(optval);
427 optval = 20;
428 if (setsockopt
429 (drv->monitor_sock, SOL_SOCKET, SO_PRIORITY, &optval, optlen)) {
430 wpa_printf(MSG_ERROR, "nl80211: Failed to set socket priority: %s",
431 strerror(errno));
432 goto error;
433 }
434
435 if (eloop_register_read_sock(drv->monitor_sock, handle_monitor_read,
436 drv, NULL)) {
437 wpa_printf(MSG_INFO, "nl80211: Could not register monitor read socket");
438 goto error;
439 }
440
441 drv->monitor_refcount++;
442 return 0;
443 error:
444 nl80211_remove_monitor_interface(drv);
445 return -1;
446 }
447
448
nl80211_send_monitor(struct wpa_driver_nl80211_data * drv,const void * data,size_t len,int encrypt,int noack)449 int nl80211_send_monitor(struct wpa_driver_nl80211_data *drv,
450 const void *data, size_t len,
451 int encrypt, int noack)
452 {
453 __u8 rtap_hdr[] = {
454 0x00, 0x00, /* radiotap version */
455 0x0e, 0x00, /* radiotap length */
456 0x02, 0xc0, 0x00, 0x00, /* bmap: flags, tx and rx flags */
457 IEEE80211_RADIOTAP_F_FRAG, /* F_FRAG (fragment if required) */
458 0x00, /* padding */
459 0x00, 0x00, /* RX and TX flags to indicate that */
460 0x00, 0x00, /* this is the injected frame directly */
461 };
462 struct iovec iov[2] = {
463 {
464 .iov_base = &rtap_hdr,
465 .iov_len = sizeof(rtap_hdr),
466 },
467 {
468 .iov_base = (void *) data,
469 .iov_len = len,
470 }
471 };
472 struct msghdr msg = {
473 .msg_name = NULL,
474 .msg_namelen = 0,
475 .msg_iov = iov,
476 .msg_iovlen = 2,
477 .msg_control = NULL,
478 .msg_controllen = 0,
479 .msg_flags = 0,
480 };
481 int res;
482 u16 txflags = 0;
483
484 if (encrypt)
485 rtap_hdr[8] |= IEEE80211_RADIOTAP_F_WEP;
486
487 if (drv->monitor_sock < 0) {
488 wpa_printf(MSG_DEBUG, "nl80211: No monitor socket available "
489 "for %s", __func__);
490 return -1;
491 }
492
493 if (noack)
494 txflags |= IEEE80211_RADIOTAP_F_TX_NOACK;
495 WPA_PUT_LE16(&rtap_hdr[12], txflags);
496
497 res = sendmsg(drv->monitor_sock, &msg, 0);
498 if (res < 0) {
499 wpa_printf(MSG_INFO, "nl80211: sendmsg: %s", strerror(errno));
500 return -1;
501 }
502 return 0;
503 }
504
