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/random.h>
25 #include <linux/rculist.h>
26 #include <linux/rcupdate.h>
27 #include <linux/rtnetlink.h>
28 #include <linux/skbuff.h>
29 #include <linux/stddef.h>
30 #include <linux/string.h>
31 #include <linux/types.h>
32 #include <linux/workqueue.h>
33 #include <net/cfg80211.h>
34 #include <uapi/linux/batadv_packet.h>
35 
36 #include "bat_algo.h"
37 #include "bat_v_ogm.h"
38 #include "hard-interface.h"
39 #include "log.h"
40 #include "originator.h"
41 #include "routing.h"
42 #include "send.h"
43 
44 /**
45  * batadv_v_elp_start_timer() - restart timer for ELP periodic work
46  * @hard_iface: the interface for which the timer has to be reset
47  */
batadv_v_elp_start_timer(struct batadv_hard_iface * hard_iface)48 static void batadv_v_elp_start_timer(struct batadv_hard_iface *hard_iface)
49 {
50 	unsigned int msecs;
51 
52 	msecs = atomic_read(&hard_iface->bat_v.elp_interval) - BATADV_JITTER;
53 	msecs += get_random_u32_below(2 * BATADV_JITTER);
54 
55 	queue_delayed_work(batadv_event_workqueue, &hard_iface->bat_v.elp_wq,
56 			   msecs_to_jiffies(msecs));
57 }
58 
59 /**
60  * batadv_v_elp_get_throughput() - get the throughput towards a neighbour
61  * @neigh: the neighbour for which the throughput has to be obtained
62  *
63  * Return: The throughput towards the given neighbour in multiples of 100kpbs
64  *         (a value of '1' equals 0.1Mbps, '10' equals 1Mbps, etc).
65  */
batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node * neigh)66 static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh)
67 {
68 	struct batadv_hard_iface *hard_iface = neigh->if_incoming;
69 	struct ethtool_link_ksettings link_settings;
70 	struct net_device *real_netdev;
71 	struct station_info sinfo;
72 	u32 throughput;
73 	int ret;
74 
75 	/* if the user specified a customised value for this interface, then
76 	 * return it directly
77 	 */
78 	throughput =  atomic_read(&hard_iface->bat_v.throughput_override);
79 	if (throughput != 0)
80 		return throughput;
81 
82 	/* if this is a wireless device, then ask its throughput through
83 	 * cfg80211 API
84 	 */
85 	if (batadv_is_wifi_hardif(hard_iface)) {
86 		if (!batadv_is_cfg80211_hardif(hard_iface))
87 			/* unsupported WiFi driver version */
88 			goto default_throughput;
89 
90 		real_netdev = batadv_get_real_netdev(hard_iface->net_dev);
91 		if (!real_netdev)
92 			goto default_throughput;
93 
94 		ret = cfg80211_get_station(real_netdev, neigh->addr, &sinfo);
95 
96 		if (!ret) {
97 			/* free the TID stats immediately */
98 			cfg80211_sinfo_release_content(&sinfo);
99 		}
100 
101 		dev_put(real_netdev);
102 		if (ret == -ENOENT) {
103 			/* Node is not associated anymore! It would be
104 			 * possible to delete this neighbor. For now set
105 			 * the throughput metric to 0.
106 			 */
107 			return 0;
108 		}
109 		if (ret)
110 			goto default_throughput;
111 
112 		if (sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT))
113 			return sinfo.expected_throughput / 100;
114 
115 		/* try to estimate the expected throughput based on reported tx
116 		 * rates
117 		 */
118 		if (sinfo.filled & BIT(NL80211_STA_INFO_TX_BITRATE))
119 			return cfg80211_calculate_bitrate(&sinfo.txrate) / 3;
120 
121 		goto default_throughput;
122 	}
123 
124 	/* if not a wifi interface, check if this device provides data via
125 	 * ethtool (e.g. an Ethernet adapter)
126 	 */
127 	rtnl_lock();
128 	ret = __ethtool_get_link_ksettings(hard_iface->net_dev, &link_settings);
129 	rtnl_unlock();
130 	if (ret == 0) {
131 		/* link characteristics might change over time */
132 		if (link_settings.base.duplex == DUPLEX_FULL)
133 			hard_iface->bat_v.flags |= BATADV_FULL_DUPLEX;
134 		else
135 			hard_iface->bat_v.flags &= ~BATADV_FULL_DUPLEX;
136 
137 		throughput = link_settings.base.speed;
138 		if (throughput && throughput != SPEED_UNKNOWN)
139 			return throughput * 10;
140 	}
141 
142 default_throughput:
143 	if (!(hard_iface->bat_v.flags & BATADV_WARNING_DEFAULT)) {
144 		batadv_info(hard_iface->soft_iface,
145 			    "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",
146 			    hard_iface->net_dev->name,
147 			    BATADV_THROUGHPUT_DEFAULT_VALUE / 10,
148 			    BATADV_THROUGHPUT_DEFAULT_VALUE % 10);
149 		hard_iface->bat_v.flags |= BATADV_WARNING_DEFAULT;
150 	}
151 
152 	/* if none of the above cases apply, return the base_throughput */
153 	return BATADV_THROUGHPUT_DEFAULT_VALUE;
154 }
155 
156 /**
157  * batadv_v_elp_throughput_metric_update() - worker updating the throughput
158  *  metric of a single hop neighbour
159  * @work: the work queue item
160  */
batadv_v_elp_throughput_metric_update(struct work_struct * work)161 void batadv_v_elp_throughput_metric_update(struct work_struct *work)
162 {
163 	struct batadv_hardif_neigh_node_bat_v *neigh_bat_v;
164 	struct batadv_hardif_neigh_node *neigh;
165 
166 	neigh_bat_v = container_of(work, struct batadv_hardif_neigh_node_bat_v,
167 				   metric_work);
168 	neigh = container_of(neigh_bat_v, struct batadv_hardif_neigh_node,
169 			     bat_v);
170 
171 	ewma_throughput_add(&neigh->bat_v.throughput,
172 			    batadv_v_elp_get_throughput(neigh));
173 
174 	/* decrement refcounter to balance increment performed before scheduling
175 	 * this task
176 	 */
177 	batadv_hardif_neigh_put(neigh);
178 }
179 
180 /**
181  * batadv_v_elp_wifi_neigh_probe() - send link probing packets to a neighbour
182  * @neigh: the neighbour to probe
183  *
184  * Sends a predefined number of unicast wifi packets to a given neighbour in
185  * order to trigger the throughput estimation on this link by the RC algorithm.
186  * Packets are sent only if there is not enough payload unicast traffic towards
187  * this neighbour..
188  *
189  * Return: True on success and false in case of error during skb preparation.
190  */
191 static bool
batadv_v_elp_wifi_neigh_probe(struct batadv_hardif_neigh_node * neigh)192 batadv_v_elp_wifi_neigh_probe(struct batadv_hardif_neigh_node *neigh)
193 {
194 	struct batadv_hard_iface *hard_iface = neigh->if_incoming;
195 	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
196 	unsigned long last_tx_diff;
197 	struct sk_buff *skb;
198 	int probe_len, i;
199 	int elp_skb_len;
200 
201 	/* this probing routine is for Wifi neighbours only */
202 	if (!batadv_is_wifi_hardif(hard_iface))
203 		return true;
204 
205 	/* probe the neighbor only if no unicast packets have been sent
206 	 * to it in the last 100 milliseconds: this is the rate control
207 	 * algorithm sampling interval (minstrel). In this way, if not
208 	 * enough traffic has been sent to the neighbor, batman-adv can
209 	 * generate 2 probe packets and push the RC algorithm to perform
210 	 * the sampling
211 	 */
212 	last_tx_diff = jiffies_to_msecs(jiffies - neigh->bat_v.last_unicast_tx);
213 	if (last_tx_diff <= BATADV_ELP_PROBE_MAX_TX_DIFF)
214 		return true;
215 
216 	probe_len = max_t(int, sizeof(struct batadv_elp_packet),
217 			  BATADV_ELP_MIN_PROBE_SIZE);
218 
219 	for (i = 0; i < BATADV_ELP_PROBES_PER_NODE; i++) {
220 		elp_skb_len = hard_iface->bat_v.elp_skb->len;
221 		skb = skb_copy_expand(hard_iface->bat_v.elp_skb, 0,
222 				      probe_len - elp_skb_len,
223 				      GFP_ATOMIC);
224 		if (!skb)
225 			return false;
226 
227 		/* Tell the skb to get as big as the allocated space (we want
228 		 * the packet to be exactly of that size to make the link
229 		 * throughput estimation effective.
230 		 */
231 		skb_put_zero(skb, probe_len - hard_iface->bat_v.elp_skb->len);
232 
233 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
234 			   "Sending unicast (probe) ELP packet on interface %s to %pM\n",
235 			   hard_iface->net_dev->name, neigh->addr);
236 
237 		batadv_send_skb_packet(skb, hard_iface, neigh->addr);
238 	}
239 
240 	return true;
241 }
242 
243 /**
244  * batadv_v_elp_periodic_work() - ELP periodic task per interface
245  * @work: work queue item
246  *
247  * Emits broadcast ELP messages in regular intervals.
248  */
batadv_v_elp_periodic_work(struct work_struct * work)249 static void batadv_v_elp_periodic_work(struct work_struct *work)
250 {
251 	struct batadv_hardif_neigh_node *hardif_neigh;
252 	struct batadv_hard_iface *hard_iface;
253 	struct batadv_hard_iface_bat_v *bat_v;
254 	struct batadv_elp_packet *elp_packet;
255 	struct batadv_priv *bat_priv;
256 	struct sk_buff *skb;
257 	u32 elp_interval;
258 	bool ret;
259 
260 	bat_v = container_of(work, struct batadv_hard_iface_bat_v, elp_wq.work);
261 	hard_iface = container_of(bat_v, struct batadv_hard_iface, bat_v);
262 	bat_priv = netdev_priv(hard_iface->soft_iface);
263 
264 	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING)
265 		goto out;
266 
267 	/* we are in the process of shutting this interface down */
268 	if (hard_iface->if_status == BATADV_IF_NOT_IN_USE ||
269 	    hard_iface->if_status == BATADV_IF_TO_BE_REMOVED)
270 		goto out;
271 
272 	/* the interface was enabled but may not be ready yet */
273 	if (hard_iface->if_status != BATADV_IF_ACTIVE)
274 		goto restart_timer;
275 
276 	skb = skb_copy(hard_iface->bat_v.elp_skb, GFP_ATOMIC);
277 	if (!skb)
278 		goto restart_timer;
279 
280 	elp_packet = (struct batadv_elp_packet *)skb->data;
281 	elp_packet->seqno = htonl(atomic_read(&hard_iface->bat_v.elp_seqno));
282 	elp_interval = atomic_read(&hard_iface->bat_v.elp_interval);
283 	elp_packet->elp_interval = htonl(elp_interval);
284 
285 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
286 		   "Sending broadcast ELP packet on interface %s, seqno %u\n",
287 		   hard_iface->net_dev->name,
288 		   atomic_read(&hard_iface->bat_v.elp_seqno));
289 
290 	batadv_send_broadcast_skb(skb, hard_iface);
291 
292 	atomic_inc(&hard_iface->bat_v.elp_seqno);
293 
294 	/* The throughput metric is updated on each sent packet. This way, if a
295 	 * node is dead and no longer sends packets, batman-adv is still able to
296 	 * react timely to its death.
297 	 *
298 	 * The throughput metric is updated by following these steps:
299 	 * 1) if the hard_iface is wifi => send a number of unicast ELPs for
300 	 *    probing/sampling to each neighbor
301 	 * 2) update the throughput metric value of each neighbor (note that the
302 	 *    value retrieved in this step might be 100ms old because the
303 	 *    probing packets at point 1) could still be in the HW queue)
304 	 */
305 	rcu_read_lock();
306 	hlist_for_each_entry_rcu(hardif_neigh, &hard_iface->neigh_list, list) {
307 		if (!batadv_v_elp_wifi_neigh_probe(hardif_neigh))
308 			/* if something goes wrong while probing, better to stop
309 			 * sending packets immediately and reschedule the task
310 			 */
311 			break;
312 
313 		if (!kref_get_unless_zero(&hardif_neigh->refcount))
314 			continue;
315 
316 		/* Reading the estimated throughput from cfg80211 is a task that
317 		 * may sleep and that is not allowed in an rcu protected
318 		 * context. Therefore schedule a task for that.
319 		 */
320 		ret = queue_work(batadv_event_workqueue,
321 				 &hardif_neigh->bat_v.metric_work);
322 
323 		if (!ret)
324 			batadv_hardif_neigh_put(hardif_neigh);
325 	}
326 	rcu_read_unlock();
327 
328 restart_timer:
329 	batadv_v_elp_start_timer(hard_iface);
330 out:
331 	return;
332 }
333 
334 /**
335  * batadv_v_elp_iface_enable() - setup the ELP interface private resources
336  * @hard_iface: interface for which the data has to be prepared
337  *
338  * Return: 0 on success or a -ENOMEM in case of failure.
339  */
batadv_v_elp_iface_enable(struct batadv_hard_iface * hard_iface)340 int batadv_v_elp_iface_enable(struct batadv_hard_iface *hard_iface)
341 {
342 	static const size_t tvlv_padding = sizeof(__be32);
343 	struct batadv_elp_packet *elp_packet;
344 	unsigned char *elp_buff;
345 	u32 random_seqno;
346 	size_t size;
347 	int res = -ENOMEM;
348 
349 	size = ETH_HLEN + NET_IP_ALIGN + BATADV_ELP_HLEN + tvlv_padding;
350 	hard_iface->bat_v.elp_skb = dev_alloc_skb(size);
351 	if (!hard_iface->bat_v.elp_skb)
352 		goto out;
353 
354 	skb_reserve(hard_iface->bat_v.elp_skb, ETH_HLEN + NET_IP_ALIGN);
355 	elp_buff = skb_put_zero(hard_iface->bat_v.elp_skb,
356 				BATADV_ELP_HLEN + tvlv_padding);
357 	elp_packet = (struct batadv_elp_packet *)elp_buff;
358 
359 	elp_packet->packet_type = BATADV_ELP;
360 	elp_packet->version = BATADV_COMPAT_VERSION;
361 
362 	/* randomize initial seqno to avoid collision */
363 	get_random_bytes(&random_seqno, sizeof(random_seqno));
364 	atomic_set(&hard_iface->bat_v.elp_seqno, random_seqno);
365 
366 	/* assume full-duplex by default */
367 	hard_iface->bat_v.flags |= BATADV_FULL_DUPLEX;
368 
369 	/* warn the user (again) if there is no throughput data is available */
370 	hard_iface->bat_v.flags &= ~BATADV_WARNING_DEFAULT;
371 
372 	if (batadv_is_wifi_hardif(hard_iface))
373 		hard_iface->bat_v.flags &= ~BATADV_FULL_DUPLEX;
374 
375 	INIT_DELAYED_WORK(&hard_iface->bat_v.elp_wq,
376 			  batadv_v_elp_periodic_work);
377 	batadv_v_elp_start_timer(hard_iface);
378 	res = 0;
379 
380 out:
381 	return res;
382 }
383 
384 /**
385  * batadv_v_elp_iface_disable() - release ELP interface private resources
386  * @hard_iface: interface for which the resources have to be released
387  */
batadv_v_elp_iface_disable(struct batadv_hard_iface * hard_iface)388 void batadv_v_elp_iface_disable(struct batadv_hard_iface *hard_iface)
389 {
390 	cancel_delayed_work_sync(&hard_iface->bat_v.elp_wq);
391 
392 	dev_kfree_skb(hard_iface->bat_v.elp_skb);
393 	hard_iface->bat_v.elp_skb = NULL;
394 }
395 
396 /**
397  * batadv_v_elp_iface_activate() - update the ELP buffer belonging to the given
398  *  hard-interface
399  * @primary_iface: the new primary interface
400  * @hard_iface: interface holding the to-be-updated buffer
401  */
batadv_v_elp_iface_activate(struct batadv_hard_iface * primary_iface,struct batadv_hard_iface * hard_iface)402 void batadv_v_elp_iface_activate(struct batadv_hard_iface *primary_iface,
403 				 struct batadv_hard_iface *hard_iface)
404 {
405 	struct batadv_elp_packet *elp_packet;
406 	struct sk_buff *skb;
407 
408 	if (!hard_iface->bat_v.elp_skb)
409 		return;
410 
411 	skb = hard_iface->bat_v.elp_skb;
412 	elp_packet = (struct batadv_elp_packet *)skb->data;
413 	ether_addr_copy(elp_packet->orig,
414 			primary_iface->net_dev->dev_addr);
415 }
416 
417 /**
418  * batadv_v_elp_primary_iface_set() - change internal data to reflect the new
419  *  primary interface
420  * @primary_iface: the new primary interface
421  */
batadv_v_elp_primary_iface_set(struct batadv_hard_iface * primary_iface)422 void batadv_v_elp_primary_iface_set(struct batadv_hard_iface *primary_iface)
423 {
424 	struct batadv_hard_iface *hard_iface;
425 
426 	/* update orig field of every elp iface belonging to this mesh */
427 	rcu_read_lock();
428 	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
429 		if (primary_iface->soft_iface != hard_iface->soft_iface)
430 			continue;
431 
432 		batadv_v_elp_iface_activate(primary_iface, hard_iface);
433 	}
434 	rcu_read_unlock();
435 }
436 
437 /**
438  * batadv_v_elp_neigh_update() - update an ELP neighbour node
439  * @bat_priv: the bat priv with all the soft interface information
440  * @neigh_addr: the neighbour interface address
441  * @if_incoming: the interface the packet was received through
442  * @elp_packet: the received ELP packet
443  *
444  * Updates the ELP neighbour node state with the data received within the new
445  * ELP packet.
446  */
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)447 static void batadv_v_elp_neigh_update(struct batadv_priv *bat_priv,
448 				      u8 *neigh_addr,
449 				      struct batadv_hard_iface *if_incoming,
450 				      struct batadv_elp_packet *elp_packet)
451 
452 {
453 	struct batadv_neigh_node *neigh;
454 	struct batadv_orig_node *orig_neigh;
455 	struct batadv_hardif_neigh_node *hardif_neigh;
456 	s32 seqno_diff;
457 	s32 elp_latest_seqno;
458 
459 	orig_neigh = batadv_v_ogm_orig_get(bat_priv, elp_packet->orig);
460 	if (!orig_neigh)
461 		return;
462 
463 	neigh = batadv_neigh_node_get_or_create(orig_neigh,
464 						if_incoming, neigh_addr);
465 	if (!neigh)
466 		goto orig_free;
467 
468 	hardif_neigh = batadv_hardif_neigh_get(if_incoming, neigh_addr);
469 	if (!hardif_neigh)
470 		goto neigh_free;
471 
472 	elp_latest_seqno = hardif_neigh->bat_v.elp_latest_seqno;
473 	seqno_diff = ntohl(elp_packet->seqno) - elp_latest_seqno;
474 
475 	/* known or older sequence numbers are ignored. However always adopt
476 	 * if the router seems to have been restarted.
477 	 */
478 	if (seqno_diff < 1 && seqno_diff > -BATADV_ELP_MAX_AGE)
479 		goto hardif_free;
480 
481 	neigh->last_seen = jiffies;
482 	hardif_neigh->last_seen = jiffies;
483 	hardif_neigh->bat_v.elp_latest_seqno = ntohl(elp_packet->seqno);
484 	hardif_neigh->bat_v.elp_interval = ntohl(elp_packet->elp_interval);
485 
486 hardif_free:
487 	batadv_hardif_neigh_put(hardif_neigh);
488 neigh_free:
489 	batadv_neigh_node_put(neigh);
490 orig_free:
491 	batadv_orig_node_put(orig_neigh);
492 }
493 
494 /**
495  * batadv_v_elp_packet_recv() - main ELP packet handler
496  * @skb: the received packet
497  * @if_incoming: the interface this packet was received through
498  *
499  * Return: NET_RX_SUCCESS and consumes the skb if the packet was properly
500  * processed or NET_RX_DROP in case of failure.
501  */
batadv_v_elp_packet_recv(struct sk_buff * skb,struct batadv_hard_iface * if_incoming)502 int batadv_v_elp_packet_recv(struct sk_buff *skb,
503 			     struct batadv_hard_iface *if_incoming)
504 {
505 	struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
506 	struct batadv_elp_packet *elp_packet;
507 	struct batadv_hard_iface *primary_if;
508 	struct ethhdr *ethhdr;
509 	bool res;
510 	int ret = NET_RX_DROP;
511 
512 	res = batadv_check_management_packet(skb, if_incoming, BATADV_ELP_HLEN);
513 	if (!res)
514 		goto free_skb;
515 
516 	ethhdr = eth_hdr(skb);
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