1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright (C) B.A.T.M.A.N. contributors:
3  *
4  * Linus Lüssing, Marek Lindner
5  */
6 
7 #include "bat_v_elp.h"
8 #include "main.h"
9 
10 #include <linux/atomic.h>
11 #include <linux/bitops.h>
12 #include <linux/byteorder/generic.h>
13 #include <linux/container_of.h>
14 #include <linux/errno.h>
15 #include <linux/etherdevice.h>
16 #include <linux/ethtool.h>
17 #include <linux/gfp.h>
18 #include <linux/if_ether.h>
19 #include <linux/jiffies.h>
20 #include <linux/kref.h>
21 #include <linux/minmax.h>
22 #include <linux/netdevice.h>
23 #include <linux/nl80211.h>
24 #include <linux/prandom.h>
25 #include <linux/random.h>
26 #include <linux/rculist.h>
27 #include <linux/rcupdate.h>
28 #include <linux/rtnetlink.h>
29 #include <linux/skbuff.h>
30 #include <linux/stddef.h>
31 #include <linux/string.h>
32 #include <linux/types.h>
33 #include <linux/workqueue.h>
34 #include <net/cfg80211.h>
35 #include <uapi/linux/batadv_packet.h>
36 
37 #include "bat_algo.h"
38 #include "bat_v_ogm.h"
39 #include "hard-interface.h"
40 #include "log.h"
41 #include "originator.h"
42 #include "routing.h"
43 #include "send.h"
44 
45 /**
46  * batadv_v_elp_start_timer() - restart timer for ELP periodic work
47  * @hard_iface: the interface for which the timer has to be reset
48  */
batadv_v_elp_start_timer(struct batadv_hard_iface * hard_iface)49 static void batadv_v_elp_start_timer(struct batadv_hard_iface *hard_iface)
50 {
51 	unsigned int msecs;
52 
53 	msecs = atomic_read(&hard_iface->bat_v.elp_interval) - BATADV_JITTER;
54 	msecs += prandom_u32_max(2 * BATADV_JITTER);
55 
56 	queue_delayed_work(batadv_event_workqueue, &hard_iface->bat_v.elp_wq,
57 			   msecs_to_jiffies(msecs));
58 }
59 
60 /**
61  * batadv_v_elp_get_throughput() - get the throughput towards a neighbour
62  * @neigh: the neighbour for which the throughput has to be obtained
63  *
64  * Return: The throughput towards the given neighbour in multiples of 100kpbs
65  *         (a value of '1' equals 0.1Mbps, '10' equals 1Mbps, etc).
66  */
batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node * neigh)67 static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh)
68 {
69 	struct batadv_hard_iface *hard_iface = neigh->if_incoming;
70 	struct ethtool_link_ksettings link_settings;
71 	struct net_device *real_netdev;
72 	struct station_info sinfo;
73 	u32 throughput;
74 	int ret;
75 
76 	/* if the user specified a customised value for this interface, then
77 	 * return it directly
78 	 */
79 	throughput =  atomic_read(&hard_iface->bat_v.throughput_override);
80 	if (throughput != 0)
81 		return throughput;
82 
83 	/* if this is a wireless device, then ask its throughput through
84 	 * cfg80211 API
85 	 */
86 	if (batadv_is_wifi_hardif(hard_iface)) {
87 		if (!batadv_is_cfg80211_hardif(hard_iface))
88 			/* unsupported WiFi driver version */
89 			goto default_throughput;
90 
91 		real_netdev = batadv_get_real_netdev(hard_iface->net_dev);
92 		if (!real_netdev)
93 			goto default_throughput;
94 
95 		ret = cfg80211_get_station(real_netdev, neigh->addr, &sinfo);
96 
97 		if (!ret) {
98 			/* free the TID stats immediately */
99 			cfg80211_sinfo_release_content(&sinfo);
100 		}
101 
102 		dev_put(real_netdev);
103 		if (ret == -ENOENT) {
104 			/* Node is not associated anymore! It would be
105 			 * possible to delete this neighbor. For now set
106 			 * the throughput metric to 0.
107 			 */
108 			return 0;
109 		}
110 		if (ret)
111 			goto default_throughput;
112 
113 		if (sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT))
114 			return sinfo.expected_throughput / 100;
115 
116 		/* try to estimate the expected throughput based on reported tx
117 		 * rates
118 		 */
119 		if (sinfo.filled & BIT(NL80211_STA_INFO_TX_BITRATE))
120 			return cfg80211_calculate_bitrate(&sinfo.txrate) / 3;
121 
122 		goto default_throughput;
123 	}
124 
125 	/* if not a wifi interface, check if this device provides data via
126 	 * ethtool (e.g. an Ethernet adapter)
127 	 */
128 	rtnl_lock();
129 	ret = __ethtool_get_link_ksettings(hard_iface->net_dev, &link_settings);
130 	rtnl_unlock();
131 	if (ret == 0) {
132 		/* link characteristics might change over time */
133 		if (link_settings.base.duplex == DUPLEX_FULL)
134 			hard_iface->bat_v.flags |= BATADV_FULL_DUPLEX;
135 		else
136 			hard_iface->bat_v.flags &= ~BATADV_FULL_DUPLEX;
137 
138 		throughput = link_settings.base.speed;
139 		if (throughput && throughput != SPEED_UNKNOWN)
140 			return throughput * 10;
141 	}
142 
143 default_throughput:
144 	if (!(hard_iface->bat_v.flags & BATADV_WARNING_DEFAULT)) {
145 		batadv_info(hard_iface->soft_iface,
146 			    "WiFi driver or ethtool info does not provide information about link speeds on interface %s, therefore defaulting to hardcoded throughput values of %u.%1u Mbps. Consider overriding the throughput manually or checking your driver.\n",
147 			    hard_iface->net_dev->name,
148 			    BATADV_THROUGHPUT_DEFAULT_VALUE / 10,
149 			    BATADV_THROUGHPUT_DEFAULT_VALUE % 10);
150 		hard_iface->bat_v.flags |= BATADV_WARNING_DEFAULT;
151 	}
152 
153 	/* if none of the above cases apply, return the base_throughput */
154 	return BATADV_THROUGHPUT_DEFAULT_VALUE;
155 }
156 
157 /**
158  * batadv_v_elp_throughput_metric_update() - worker updating the throughput
159  *  metric of a single hop neighbour
160  * @work: the work queue item
161  */
batadv_v_elp_throughput_metric_update(struct work_struct * work)162 void batadv_v_elp_throughput_metric_update(struct work_struct *work)
163 {
164 	struct batadv_hardif_neigh_node_bat_v *neigh_bat_v;
165 	struct batadv_hardif_neigh_node *neigh;
166 
167 	neigh_bat_v = container_of(work, struct batadv_hardif_neigh_node_bat_v,
168 				   metric_work);
169 	neigh = container_of(neigh_bat_v, struct batadv_hardif_neigh_node,
170 			     bat_v);
171 
172 	ewma_throughput_add(&neigh->bat_v.throughput,
173 			    batadv_v_elp_get_throughput(neigh));
174 
175 	/* decrement refcounter to balance increment performed before scheduling
176 	 * this task
177 	 */
178 	batadv_hardif_neigh_put(neigh);
179 }
180 
181 /**
182  * batadv_v_elp_wifi_neigh_probe() - send link probing packets to a neighbour
183  * @neigh: the neighbour to probe
184  *
185  * Sends a predefined number of unicast wifi packets to a given neighbour in
186  * order to trigger the throughput estimation on this link by the RC algorithm.
187  * Packets are sent only if there is not enough payload unicast traffic towards
188  * this neighbour..
189  *
190  * Return: True on success and false in case of error during skb preparation.
191  */
192 static bool
batadv_v_elp_wifi_neigh_probe(struct batadv_hardif_neigh_node * neigh)193 batadv_v_elp_wifi_neigh_probe(struct batadv_hardif_neigh_node *neigh)
194 {
195 	struct batadv_hard_iface *hard_iface = neigh->if_incoming;
196 	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
197 	unsigned long last_tx_diff;
198 	struct sk_buff *skb;
199 	int probe_len, i;
200 	int elp_skb_len;
201 
202 	/* this probing routine is for Wifi neighbours only */
203 	if (!batadv_is_wifi_hardif(hard_iface))
204 		return true;
205 
206 	/* probe the neighbor only if no unicast packets have been sent
207 	 * to it in the last 100 milliseconds: this is the rate control
208 	 * algorithm sampling interval (minstrel). In this way, if not
209 	 * enough traffic has been sent to the neighbor, batman-adv can
210 	 * generate 2 probe packets and push the RC algorithm to perform
211 	 * the sampling
212 	 */
213 	last_tx_diff = jiffies_to_msecs(jiffies - neigh->bat_v.last_unicast_tx);
214 	if (last_tx_diff <= BATADV_ELP_PROBE_MAX_TX_DIFF)
215 		return true;
216 
217 	probe_len = max_t(int, sizeof(struct batadv_elp_packet),
218 			  BATADV_ELP_MIN_PROBE_SIZE);
219 
220 	for (i = 0; i < BATADV_ELP_PROBES_PER_NODE; i++) {
221 		elp_skb_len = hard_iface->bat_v.elp_skb->len;
222 		skb = skb_copy_expand(hard_iface->bat_v.elp_skb, 0,
223 				      probe_len - elp_skb_len,
224 				      GFP_ATOMIC);
225 		if (!skb)
226 			return false;
227 
228 		/* Tell the skb to get as big as the allocated space (we want
229 		 * the packet to be exactly of that size to make the link
230 		 * throughput estimation effective.
231 		 */
232 		skb_put_zero(skb, probe_len - hard_iface->bat_v.elp_skb->len);
233 
234 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
235 			   "Sending unicast (probe) ELP packet on interface %s to %pM\n",
236 			   hard_iface->net_dev->name, neigh->addr);
237 
238 		batadv_send_skb_packet(skb, hard_iface, neigh->addr);
239 	}
240 
241 	return true;
242 }
243 
244 /**
245  * batadv_v_elp_periodic_work() - ELP periodic task per interface
246  * @work: work queue item
247  *
248  * Emits broadcast ELP messages in regular intervals.
249  */
batadv_v_elp_periodic_work(struct work_struct * work)250 static void batadv_v_elp_periodic_work(struct work_struct *work)
251 {
252 	struct batadv_hardif_neigh_node *hardif_neigh;
253 	struct batadv_hard_iface *hard_iface;
254 	struct batadv_hard_iface_bat_v *bat_v;
255 	struct batadv_elp_packet *elp_packet;
256 	struct batadv_priv *bat_priv;
257 	struct sk_buff *skb;
258 	u32 elp_interval;
259 	bool ret;
260 
261 	bat_v = container_of(work, struct batadv_hard_iface_bat_v, elp_wq.work);
262 	hard_iface = container_of(bat_v, struct batadv_hard_iface, bat_v);
263 	bat_priv = netdev_priv(hard_iface->soft_iface);
264 
265 	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING)
266 		goto out;
267 
268 	/* we are in the process of shutting this interface down */
269 	if (hard_iface->if_status == BATADV_IF_NOT_IN_USE ||
270 	    hard_iface->if_status == BATADV_IF_TO_BE_REMOVED)
271 		goto out;
272 
273 	/* the interface was enabled but may not be ready yet */
274 	if (hard_iface->if_status != BATADV_IF_ACTIVE)
275 		goto restart_timer;
276 
277 	skb = skb_copy(hard_iface->bat_v.elp_skb, GFP_ATOMIC);
278 	if (!skb)
279 		goto restart_timer;
280 
281 	elp_packet = (struct batadv_elp_packet *)skb->data;
282 	elp_packet->seqno = htonl(atomic_read(&hard_iface->bat_v.elp_seqno));
283 	elp_interval = atomic_read(&hard_iface->bat_v.elp_interval);
284 	elp_packet->elp_interval = htonl(elp_interval);
285 
286 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
287 		   "Sending broadcast ELP packet on interface %s, seqno %u\n",
288 		   hard_iface->net_dev->name,
289 		   atomic_read(&hard_iface->bat_v.elp_seqno));
290 
291 	batadv_send_broadcast_skb(skb, hard_iface);
292 
293 	atomic_inc(&hard_iface->bat_v.elp_seqno);
294 
295 	/* The throughput metric is updated on each sent packet. This way, if a
296 	 * node is dead and no longer sends packets, batman-adv is still able to
297 	 * react timely to its death.
298 	 *
299 	 * The throughput metric is updated by following these steps:
300 	 * 1) if the hard_iface is wifi => send a number of unicast ELPs for
301 	 *    probing/sampling to each neighbor
302 	 * 2) update the throughput metric value of each neighbor (note that the
303 	 *    value retrieved in this step might be 100ms old because the
304 	 *    probing packets at point 1) could still be in the HW queue)
305 	 */
306 	rcu_read_lock();
307 	hlist_for_each_entry_rcu(hardif_neigh, &hard_iface->neigh_list, list) {
308 		if (!batadv_v_elp_wifi_neigh_probe(hardif_neigh))
309 			/* if something goes wrong while probing, better to stop
310 			 * sending packets immediately and reschedule the task
311 			 */
312 			break;
313 
314 		if (!kref_get_unless_zero(&hardif_neigh->refcount))
315 			continue;
316 
317 		/* Reading the estimated throughput from cfg80211 is a task that
318 		 * may sleep and that is not allowed in an rcu protected
319 		 * context. Therefore schedule a task for that.
320 		 */
321 		ret = queue_work(batadv_event_workqueue,
322 				 &hardif_neigh->bat_v.metric_work);
323 
324 		if (!ret)
325 			batadv_hardif_neigh_put(hardif_neigh);
326 	}
327 	rcu_read_unlock();
328 
329 restart_timer:
330 	batadv_v_elp_start_timer(hard_iface);
331 out:
332 	return;
333 }
334 
335 /**
336  * batadv_v_elp_iface_enable() - setup the ELP interface private resources
337  * @hard_iface: interface for which the data has to be prepared
338  *
339  * Return: 0 on success or a -ENOMEM in case of failure.
340  */
batadv_v_elp_iface_enable(struct batadv_hard_iface * hard_iface)341 int batadv_v_elp_iface_enable(struct batadv_hard_iface *hard_iface)
342 {
343 	static const size_t tvlv_padding = sizeof(__be32);
344 	struct batadv_elp_packet *elp_packet;
345 	unsigned char *elp_buff;
346 	u32 random_seqno;
347 	size_t size;
348 	int res = -ENOMEM;
349 
350 	size = ETH_HLEN + NET_IP_ALIGN + BATADV_ELP_HLEN + tvlv_padding;
351 	hard_iface->bat_v.elp_skb = dev_alloc_skb(size);
352 	if (!hard_iface->bat_v.elp_skb)
353 		goto out;
354 
355 	skb_reserve(hard_iface->bat_v.elp_skb, ETH_HLEN + NET_IP_ALIGN);
356 	elp_buff = skb_put_zero(hard_iface->bat_v.elp_skb,
357 				BATADV_ELP_HLEN + tvlv_padding);
358 	elp_packet = (struct batadv_elp_packet *)elp_buff;
359 
360 	elp_packet->packet_type = BATADV_ELP;
361 	elp_packet->version = BATADV_COMPAT_VERSION;
362 
363 	/* randomize initial seqno to avoid collision */
364 	get_random_bytes(&random_seqno, sizeof(random_seqno));
365 	atomic_set(&hard_iface->bat_v.elp_seqno, random_seqno);
366 
367 	/* assume full-duplex by default */
368 	hard_iface->bat_v.flags |= BATADV_FULL_DUPLEX;
369 
370 	/* warn the user (again) if there is no throughput data is available */
371 	hard_iface->bat_v.flags &= ~BATADV_WARNING_DEFAULT;
372 
373 	if (batadv_is_wifi_hardif(hard_iface))
374 		hard_iface->bat_v.flags &= ~BATADV_FULL_DUPLEX;
375 
376 	INIT_DELAYED_WORK(&hard_iface->bat_v.elp_wq,
377 			  batadv_v_elp_periodic_work);
378 	batadv_v_elp_start_timer(hard_iface);
379 	res = 0;
380 
381 out:
382 	return res;
383 }
384 
385 /**
386  * batadv_v_elp_iface_disable() - release ELP interface private resources
387  * @hard_iface: interface for which the resources have to be released
388  */
batadv_v_elp_iface_disable(struct batadv_hard_iface * hard_iface)389 void batadv_v_elp_iface_disable(struct batadv_hard_iface *hard_iface)
390 {
391 	cancel_delayed_work_sync(&hard_iface->bat_v.elp_wq);
392 
393 	dev_kfree_skb(hard_iface->bat_v.elp_skb);
394 	hard_iface->bat_v.elp_skb = NULL;
395 }
396 
397 /**
398  * batadv_v_elp_iface_activate() - update the ELP buffer belonging to the given
399  *  hard-interface
400  * @primary_iface: the new primary interface
401  * @hard_iface: interface holding the to-be-updated buffer
402  */
batadv_v_elp_iface_activate(struct batadv_hard_iface * primary_iface,struct batadv_hard_iface * hard_iface)403 void batadv_v_elp_iface_activate(struct batadv_hard_iface *primary_iface,
404 				 struct batadv_hard_iface *hard_iface)
405 {
406 	struct batadv_elp_packet *elp_packet;
407 	struct sk_buff *skb;
408 
409 	if (!hard_iface->bat_v.elp_skb)
410 		return;
411 
412 	skb = hard_iface->bat_v.elp_skb;
413 	elp_packet = (struct batadv_elp_packet *)skb->data;
414 	ether_addr_copy(elp_packet->orig,
415 			primary_iface->net_dev->dev_addr);
416 }
417 
418 /**
419  * batadv_v_elp_primary_iface_set() - change internal data to reflect the new
420  *  primary interface
421  * @primary_iface: the new primary interface
422  */
batadv_v_elp_primary_iface_set(struct batadv_hard_iface * primary_iface)423 void batadv_v_elp_primary_iface_set(struct batadv_hard_iface *primary_iface)
424 {
425 	struct batadv_hard_iface *hard_iface;
426 
427 	/* update orig field of every elp iface belonging to this mesh */
428 	rcu_read_lock();
429 	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
430 		if (primary_iface->soft_iface != hard_iface->soft_iface)
431 			continue;
432 
433 		batadv_v_elp_iface_activate(primary_iface, hard_iface);
434 	}
435 	rcu_read_unlock();
436 }
437 
438 /**
439  * batadv_v_elp_neigh_update() - update an ELP neighbour node
440  * @bat_priv: the bat priv with all the soft interface information
441  * @neigh_addr: the neighbour interface address
442  * @if_incoming: the interface the packet was received through
443  * @elp_packet: the received ELP packet
444  *
445  * Updates the ELP neighbour node state with the data received within the new
446  * ELP packet.
447  */
batadv_v_elp_neigh_update(struct batadv_priv * bat_priv,u8 * neigh_addr,struct batadv_hard_iface * if_incoming,struct batadv_elp_packet * elp_packet)448 static void batadv_v_elp_neigh_update(struct batadv_priv *bat_priv,
449 				      u8 *neigh_addr,
450 				      struct batadv_hard_iface *if_incoming,
451 				      struct batadv_elp_packet *elp_packet)
452 
453 {
454 	struct batadv_neigh_node *neigh;
455 	struct batadv_orig_node *orig_neigh;
456 	struct batadv_hardif_neigh_node *hardif_neigh;
457 	s32 seqno_diff;
458 	s32 elp_latest_seqno;
459 
460 	orig_neigh = batadv_v_ogm_orig_get(bat_priv, elp_packet->orig);
461 	if (!orig_neigh)
462 		return;
463 
464 	neigh = batadv_neigh_node_get_or_create(orig_neigh,
465 						if_incoming, neigh_addr);
466 	if (!neigh)
467 		goto orig_free;
468 
469 	hardif_neigh = batadv_hardif_neigh_get(if_incoming, neigh_addr);
470 	if (!hardif_neigh)
471 		goto neigh_free;
472 
473 	elp_latest_seqno = hardif_neigh->bat_v.elp_latest_seqno;
474 	seqno_diff = ntohl(elp_packet->seqno) - elp_latest_seqno;
475 
476 	/* known or older sequence numbers are ignored. However always adopt
477 	 * if the router seems to have been restarted.
478 	 */
479 	if (seqno_diff < 1 && seqno_diff > -BATADV_ELP_MAX_AGE)
480 		goto hardif_free;
481 
482 	neigh->last_seen = jiffies;
483 	hardif_neigh->last_seen = jiffies;
484 	hardif_neigh->bat_v.elp_latest_seqno = ntohl(elp_packet->seqno);
485 	hardif_neigh->bat_v.elp_interval = ntohl(elp_packet->elp_interval);
486 
487 hardif_free:
488 	batadv_hardif_neigh_put(hardif_neigh);
489 neigh_free:
490 	batadv_neigh_node_put(neigh);
491 orig_free:
492 	batadv_orig_node_put(orig_neigh);
493 }
494 
495 /**
496  * batadv_v_elp_packet_recv() - main ELP packet handler
497  * @skb: the received packet
498  * @if_incoming: the interface this packet was received through
499  *
500  * Return: NET_RX_SUCCESS and consumes the skb if the packet was properly
501  * processed or NET_RX_DROP in case of failure.
502  */
batadv_v_elp_packet_recv(struct sk_buff * skb,struct batadv_hard_iface * if_incoming)503 int batadv_v_elp_packet_recv(struct sk_buff *skb,
504 			     struct batadv_hard_iface *if_incoming)
505 {
506 	struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
507 	struct batadv_elp_packet *elp_packet;
508 	struct batadv_hard_iface *primary_if;
509 	struct ethhdr *ethhdr = (struct ethhdr *)skb_mac_header(skb);
510 	bool res;
511 	int ret = NET_RX_DROP;
512 
513 	res = batadv_check_management_packet(skb, if_incoming, BATADV_ELP_HLEN);
514 	if (!res)
515 		goto free_skb;
516 
517 	if (batadv_is_my_mac(bat_priv, ethhdr->h_source))
518 		goto free_skb;
519 
520 	/* did we receive a B.A.T.M.A.N. V ELP packet on an interface
521 	 * that does not have B.A.T.M.A.N. V ELP enabled ?
522 	 */
523 	if (strcmp(bat_priv->algo_ops->name, "BATMAN_V") != 0)
524 		goto free_skb;
525 
526 	elp_packet = (struct batadv_elp_packet *)skb->data;
527 
528 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
529 		   "Received ELP packet from %pM seqno %u ORIG: %pM\n",
530 		   ethhdr->h_source, ntohl(elp_packet->seqno),
531 		   elp_packet->orig);
532 
533 	primary_if = batadv_primary_if_get_selected(bat_priv);
534 	if (!primary_if)
535 		goto free_skb;
536 
537 	batadv_v_elp_neigh_update(bat_priv, ethhdr->h_source, if_incoming,
538 				  elp_packet);
539 
540 	ret = NET_RX_SUCCESS;
541 	batadv_hardif_put(primary_if);
542 
543 free_skb:
544 	if (ret == NET_RX_SUCCESS)
545 		consume_skb(skb);
546 	else
547 		kfree_skb(skb);
548 
549 	return ret;
550 }
551