1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause
3 *
4 * Copyright (c) 2007-2008 Sam Leffler, Errno Consulting
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26 */
27
28 /*
29 * IEEE 802.11 DFS/Radar support.
30 */
31 #include "opt_inet.h"
32 #include "opt_wlan.h"
33
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/mbuf.h>
37 #include <sys/malloc.h>
38 #include <sys/kernel.h>
39
40 #include <sys/socket.h>
41 #include <sys/sockio.h>
42 #include <sys/endian.h>
43 #include <sys/errno.h>
44 #include <sys/proc.h>
45 #include <sys/sysctl.h>
46
47 #include <net/if.h>
48 #include <net/if_var.h>
49 #include <net/if_media.h>
50 #include <net/ethernet.h>
51
52 #include <net80211/ieee80211_var.h>
53
54 static MALLOC_DEFINE(M_80211_DFS, "80211dfs", "802.11 DFS state");
55
56 static int ieee80211_nol_timeout = 30*60; /* 30 minutes */
57 SYSCTL_INT(_net_wlan, OID_AUTO, nol_timeout, CTLFLAG_RW,
58 &ieee80211_nol_timeout, 0, "NOL timeout (secs)");
59 #define NOL_TIMEOUT msecs_to_ticks(ieee80211_nol_timeout*1000)
60
61 static int ieee80211_cac_timeout = 60; /* 60 seconds */
62 SYSCTL_INT(_net_wlan, OID_AUTO, cac_timeout, CTLFLAG_RW,
63 &ieee80211_cac_timeout, 0, "CAC timeout (secs)");
64 #define CAC_TIMEOUT msecs_to_ticks(ieee80211_cac_timeout*1000)
65
66 /*
67 DFS* In order to facilitate debugging, a couple of operating
68 * modes aside from the default are needed.
69 *
70 * 0 - default CAC/NOL behaviour - ie, start CAC, place
71 * channel on NOL list.
72 * 1 - send CAC, but don't change channel or add the channel
73 * to the NOL list.
74 * 2 - just match on radar, don't send CAC or place channel in
75 * the NOL list.
76 */
77 static int ieee80211_dfs_debug = DFS_DBG_NONE;
78
79 /*
80 * This option must not be included in the default kernel
81 * as it allows users to plainly disable CAC/NOL handling.
82 */
83 #ifdef IEEE80211_DFS_DEBUG
84 SYSCTL_INT(_net_wlan, OID_AUTO, dfs_debug, CTLFLAG_RW,
85 &ieee80211_dfs_debug, 0, "DFS debug behaviour");
86 #endif
87
88 static int
null_set_quiet(struct ieee80211_node * ni,u_int8_t * quiet_elm)89 null_set_quiet(struct ieee80211_node *ni, u_int8_t *quiet_elm)
90 {
91 return ENOSYS;
92 }
93
94 void
ieee80211_dfs_attach(struct ieee80211com * ic)95 ieee80211_dfs_attach(struct ieee80211com *ic)
96 {
97 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
98
99 callout_init_mtx(&dfs->nol_timer, IEEE80211_LOCK_OBJ(ic), 0);
100 callout_init_mtx(&dfs->cac_timer, IEEE80211_LOCK_OBJ(ic), 0);
101
102 ic->ic_set_quiet = null_set_quiet;
103 }
104
105 void
ieee80211_dfs_detach(struct ieee80211com * ic)106 ieee80211_dfs_detach(struct ieee80211com *ic)
107 {
108 /* NB: we assume no locking is needed */
109 ieee80211_dfs_reset(ic);
110 }
111
112 void
ieee80211_dfs_reset(struct ieee80211com * ic)113 ieee80211_dfs_reset(struct ieee80211com *ic)
114 {
115 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
116 int i;
117
118 /* NB: we assume no locking is needed */
119 /* NB: cac_timer should be cleared by the state machine */
120 callout_drain(&dfs->nol_timer);
121 for (i = 0; i < ic->ic_nchans; i++)
122 ic->ic_channels[i].ic_state = 0;
123 dfs->lastchan = NULL;
124 }
125
126 static void
cac_timeout(void * arg)127 cac_timeout(void *arg)
128 {
129 struct ieee80211vap *vap = arg;
130 struct ieee80211com *ic = vap->iv_ic;
131 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
132 int i;
133
134 IEEE80211_LOCK_ASSERT(ic);
135
136 if (vap->iv_state != IEEE80211_S_CAC) /* NB: just in case */
137 return;
138 /*
139 * When radar is detected during a CAC we are woken
140 * up prematurely to switch to a new channel.
141 * Check the channel to decide how to act.
142 */
143 if (IEEE80211_IS_CHAN_RADAR(ic->ic_curchan)) {
144 ieee80211_notify_cac(ic, ic->ic_curchan,
145 IEEE80211_NOTIFY_CAC_RADAR);
146
147 if_printf(vap->iv_ifp,
148 "CAC timer on channel %u (%u MHz) stopped due to radar\n",
149 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
150
151 /* XXX clobbers any existing desired channel */
152 /* NB: dfs->newchan may be NULL, that's ok */
153 vap->iv_des_chan = dfs->newchan;
154 ieee80211_new_state_locked(vap, IEEE80211_S_SCAN, 0);
155 } else {
156 if_printf(vap->iv_ifp,
157 "CAC timer on channel %u (%u MHz) expired; "
158 "no radar detected\n",
159 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
160 /*
161 * Mark all channels with the current frequency
162 * as having completed CAC; this keeps us from
163 * doing it again until we change channels.
164 */
165 for (i = 0; i < ic->ic_nchans; i++) {
166 struct ieee80211_channel *c = &ic->ic_channels[i];
167 if (c->ic_freq == ic->ic_curchan->ic_freq)
168 c->ic_state |= IEEE80211_CHANSTATE_CACDONE;
169 }
170 ieee80211_notify_cac(ic, ic->ic_curchan,
171 IEEE80211_NOTIFY_CAC_EXPIRE);
172 ieee80211_cac_completeswitch(vap);
173 }
174 }
175
176 /*
177 * Initiate the CAC timer. The driver is responsible
178 * for setting up the hardware to scan for radar on the
179 * channnel, we just handle timing things out.
180 */
181 void
ieee80211_dfs_cac_start(struct ieee80211vap * vap)182 ieee80211_dfs_cac_start(struct ieee80211vap *vap)
183 {
184 struct ieee80211com *ic = vap->iv_ic;
185 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
186
187 IEEE80211_LOCK_ASSERT(ic);
188
189 callout_reset(&dfs->cac_timer, CAC_TIMEOUT, cac_timeout, vap);
190 if_printf(vap->iv_ifp, "start %d second CAC timer on channel %u (%u MHz)\n",
191 ticks_to_secs(CAC_TIMEOUT),
192 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
193 ieee80211_notify_cac(ic, ic->ic_curchan, IEEE80211_NOTIFY_CAC_START);
194 }
195
196 /*
197 * Clear the CAC timer.
198 */
199 void
ieee80211_dfs_cac_stop(struct ieee80211vap * vap)200 ieee80211_dfs_cac_stop(struct ieee80211vap *vap)
201 {
202 struct ieee80211com *ic = vap->iv_ic;
203 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
204
205 IEEE80211_LOCK_ASSERT(ic);
206
207 /* NB: racey but not important */
208 if (callout_pending(&dfs->cac_timer)) {
209 if_printf(vap->iv_ifp, "stop CAC timer on channel %u (%u MHz)\n",
210 ic->ic_curchan->ic_ieee, ic->ic_curchan->ic_freq);
211 ieee80211_notify_cac(ic, ic->ic_curchan,
212 IEEE80211_NOTIFY_CAC_STOP);
213 }
214 callout_stop(&dfs->cac_timer);
215 }
216
217 void
ieee80211_dfs_cac_clear(struct ieee80211com * ic,const struct ieee80211_channel * chan)218 ieee80211_dfs_cac_clear(struct ieee80211com *ic,
219 const struct ieee80211_channel *chan)
220 {
221 int i;
222
223 for (i = 0; i < ic->ic_nchans; i++) {
224 struct ieee80211_channel *c = &ic->ic_channels[i];
225 if (c->ic_freq == chan->ic_freq)
226 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
227 }
228 }
229
230 static void
dfs_timeout(void * arg)231 dfs_timeout(void *arg)
232 {
233 struct ieee80211com *ic = arg;
234 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
235 struct ieee80211_channel *c;
236 int i, oldest, now;
237
238 IEEE80211_LOCK_ASSERT(ic);
239
240 now = oldest = ticks;
241 for (i = 0; i < ic->ic_nchans; i++) {
242 c = &ic->ic_channels[i];
243 if (IEEE80211_IS_CHAN_RADAR(c)) {
244 if (ieee80211_time_after_eq(now, dfs->nol_event[i]+NOL_TIMEOUT)) {
245 c->ic_state &= ~IEEE80211_CHANSTATE_RADAR;
246 if (c->ic_state & IEEE80211_CHANSTATE_NORADAR) {
247 /*
248 * NB: do this here so we get only one
249 * msg instead of one for every channel
250 * table entry.
251 */
252 ic_printf(ic, "radar on channel %u "
253 "(%u MHz) cleared after timeout\n",
254 c->ic_ieee, c->ic_freq);
255 /* notify user space */
256 c->ic_state &=
257 ~IEEE80211_CHANSTATE_NORADAR;
258 ieee80211_notify_radar(ic, c);
259 }
260 } else if (dfs->nol_event[i] < oldest)
261 oldest = dfs->nol_event[i];
262 }
263 }
264 if (oldest != now) {
265 /* arrange to process next channel up for a status change */
266 callout_schedule(&dfs->nol_timer, oldest + NOL_TIMEOUT - now);
267 }
268 }
269
270 static void
announce_radar(struct ieee80211com * ic,const struct ieee80211_channel * curchan,const struct ieee80211_channel * newchan)271 announce_radar(struct ieee80211com *ic, const struct ieee80211_channel *curchan,
272 const struct ieee80211_channel *newchan)
273 {
274 if (newchan == NULL)
275 ic_printf(ic, "radar detected on channel %u (%u MHz)\n",
276 curchan->ic_ieee, curchan->ic_freq);
277 else
278 ic_printf(ic, "radar detected on channel %u (%u MHz), "
279 "moving to channel %u (%u MHz)\n",
280 curchan->ic_ieee, curchan->ic_freq,
281 newchan->ic_ieee, newchan->ic_freq);
282 }
283
284 /*
285 * Handle a radar detection event on a channel. The channel is
286 * added to the NOL list and we record the time of the event.
287 * Entries are aged out after NOL_TIMEOUT. If radar was
288 * detected while doing CAC we force a state/channel change.
289 * Otherwise radar triggers a channel switch using the CSA
290 * mechanism (when the channel is the bss channel).
291 */
292 void
ieee80211_dfs_notify_radar(struct ieee80211com * ic,struct ieee80211_channel * chan)293 ieee80211_dfs_notify_radar(struct ieee80211com *ic, struct ieee80211_channel *chan)
294 {
295 struct ieee80211_dfs_state *dfs = &ic->ic_dfs;
296 int i, now;
297
298 IEEE80211_LOCK_ASSERT(ic);
299
300 /*
301 * If doing DFS debugging (mode 2), don't bother
302 * running the rest of this function.
303 *
304 * Simply announce the presence of the radar and continue
305 * along merrily.
306 */
307 if (ieee80211_dfs_debug == DFS_DBG_NOCSANOL) {
308 announce_radar(ic, chan, chan);
309 ieee80211_notify_radar(ic, chan);
310 return;
311 }
312
313 /*
314 * Don't mark the channel and don't put it into NOL
315 * if we're doing DFS debugging.
316 */
317 if (ieee80211_dfs_debug == DFS_DBG_NONE) {
318 /*
319 * Mark all entries with this frequency. Notify user
320 * space and arrange for notification when the radar
321 * indication is cleared. Then kick the NOL processing
322 * thread if not already running.
323 */
324 now = ticks;
325 for (i = 0; i < ic->ic_nchans; i++) {
326 struct ieee80211_channel *c = &ic->ic_channels[i];
327 if (c->ic_freq == chan->ic_freq) {
328 c->ic_state &= ~IEEE80211_CHANSTATE_CACDONE;
329 c->ic_state |= IEEE80211_CHANSTATE_RADAR;
330 dfs->nol_event[i] = now;
331 }
332 }
333 ieee80211_notify_radar(ic, chan);
334 chan->ic_state |= IEEE80211_CHANSTATE_NORADAR;
335 if (!callout_pending(&dfs->nol_timer))
336 callout_reset(&dfs->nol_timer, NOL_TIMEOUT,
337 dfs_timeout, ic);
338 }
339
340 /*
341 * If radar is detected on the bss channel while
342 * doing CAC; force a state change by scheduling the
343 * callout to be dispatched asap. Otherwise, if this
344 * event is for the bss channel then we must quiet
345 * traffic and schedule a channel switch.
346 *
347 * Note this allows us to receive notification about
348 * channels other than the bss channel; not sure
349 * that can/will happen but it's simple to support.
350 */
351 if (chan == ic->ic_bsschan) {
352 /* XXX need a way to defer to user app */
353
354 /*
355 * Don't flip over to a new channel if
356 * we are currently doing DFS debugging.
357 */
358 if (ieee80211_dfs_debug == DFS_DBG_NONE)
359 dfs->newchan = ieee80211_dfs_pickchannel(ic);
360 else
361 dfs->newchan = chan;
362
363 announce_radar(ic, chan, dfs->newchan);
364
365 if (callout_pending(&dfs->cac_timer))
366 callout_schedule(&dfs->cac_timer, 0);
367 else if (dfs->newchan != NULL) {
368 /* XXX mode 1, switch count 2 */
369 /* XXX calculate switch count based on max
370 switch time and beacon interval? */
371 ieee80211_csa_startswitch(ic, dfs->newchan, 1, 2);
372 } else {
373 /*
374 * Spec says to stop all transmissions and
375 * wait on the current channel for an entry
376 * on the NOL to expire.
377 */
378 /*XXX*/
379 ic_printf(ic, "%s: No free channels; waiting for entry "
380 "on NOL to expire\n", __func__);
381 }
382 } else {
383 /*
384 * Issue rate-limited console msgs.
385 */
386 if (dfs->lastchan != chan) {
387 dfs->lastchan = chan;
388 dfs->cureps = 0;
389 announce_radar(ic, chan, NULL);
390 } else if (ppsratecheck(&dfs->lastevent, &dfs->cureps, 1)) {
391 announce_radar(ic, chan, NULL);
392 }
393 }
394 }
395
396 struct ieee80211_channel *
ieee80211_dfs_pickchannel(struct ieee80211com * ic)397 ieee80211_dfs_pickchannel(struct ieee80211com *ic)
398 {
399 struct ieee80211_channel *c;
400 int i, flags;
401 uint16_t v;
402
403 /*
404 * Consult the scan cache first.
405 */
406 flags = ic->ic_curchan->ic_flags & IEEE80211_CHAN_ALL;
407 /*
408 * XXX if curchan is HT this will never find a channel
409 * XXX 'cuz we scan only legacy channels
410 */
411 c = ieee80211_scan_pickchannel(ic, flags);
412 if (c != NULL)
413 return c;
414 /*
415 * No channel found in scan cache; select a compatible
416 * one at random (skipping channels where radar has
417 * been detected).
418 */
419 net80211_get_random_bytes(&v, sizeof(v));
420 v %= ic->ic_nchans;
421 for (i = v; i < ic->ic_nchans; i++) {
422 c = &ic->ic_channels[i];
423 if (!IEEE80211_IS_CHAN_RADAR(c) &&
424 (c->ic_flags & flags) == flags)
425 return c;
426 }
427 for (i = 0; i < v; i++) {
428 c = &ic->ic_channels[i];
429 if (!IEEE80211_IS_CHAN_RADAR(c) &&
430 (c->ic_flags & flags) == flags)
431 return c;
432 }
433 ic_printf(ic, "HELP, no channel located to switch to!\n");
434 return NULL;
435 }
436