xref: /openbmc/linux/net/hsr/hsr_framereg.c (revision f17f06a0)
1 // SPDX-License-Identifier: GPL-2.0
2 /* Copyright 2011-2014 Autronica Fire and Security AS
3  *
4  * Author(s):
5  *	2011-2014 Arvid Brodin, arvid.brodin@alten.se
6  *
7  * The HSR spec says never to forward the same frame twice on the same
8  * interface. A frame is identified by its source MAC address and its HSR
9  * sequence number. This code keeps track of senders and their sequence numbers
10  * to allow filtering of duplicate frames, and to detect HSR ring errors.
11  */
12 
13 #include <linux/if_ether.h>
14 #include <linux/etherdevice.h>
15 #include <linux/slab.h>
16 #include <linux/rculist.h>
17 #include "hsr_main.h"
18 #include "hsr_framereg.h"
19 #include "hsr_netlink.h"
20 
21 /*	TODO: use hash lists for mac addresses (linux/jhash.h)?    */
22 
23 /* seq_nr_after(a, b) - return true if a is after (higher in sequence than) b,
24  * false otherwise.
25  */
26 static bool seq_nr_after(u16 a, u16 b)
27 {
28 	/* Remove inconsistency where
29 	 * seq_nr_after(a, b) == seq_nr_before(a, b)
30 	 */
31 	if ((int)b - a == 32768)
32 		return false;
33 
34 	return (((s16)(b - a)) < 0);
35 }
36 
37 #define seq_nr_before(a, b)		seq_nr_after((b), (a))
38 #define seq_nr_before_or_eq(a, b)	(!seq_nr_after((a), (b)))
39 
40 bool hsr_addr_is_self(struct hsr_priv *hsr, unsigned char *addr)
41 {
42 	struct hsr_node *node;
43 
44 	node = list_first_or_null_rcu(&hsr->self_node_db, struct hsr_node,
45 				      mac_list);
46 	if (!node) {
47 		WARN_ONCE(1, "HSR: No self node\n");
48 		return false;
49 	}
50 
51 	if (ether_addr_equal(addr, node->macaddress_A))
52 		return true;
53 	if (ether_addr_equal(addr, node->macaddress_B))
54 		return true;
55 
56 	return false;
57 }
58 
59 /* Search for mac entry. Caller must hold rcu read lock.
60  */
61 static struct hsr_node *find_node_by_addr_A(struct list_head *node_db,
62 					    const unsigned char addr[ETH_ALEN])
63 {
64 	struct hsr_node *node;
65 
66 	list_for_each_entry_rcu(node, node_db, mac_list) {
67 		if (ether_addr_equal(node->macaddress_A, addr))
68 			return node;
69 	}
70 
71 	return NULL;
72 }
73 
74 /* Helper for device init; the self_node_db is used in hsr_rcv() to recognize
75  * frames from self that's been looped over the HSR ring.
76  */
77 int hsr_create_self_node(struct hsr_priv *hsr,
78 			 unsigned char addr_a[ETH_ALEN],
79 			 unsigned char addr_b[ETH_ALEN])
80 {
81 	struct list_head *self_node_db = &hsr->self_node_db;
82 	struct hsr_node *node, *oldnode;
83 
84 	node = kmalloc(sizeof(*node), GFP_KERNEL);
85 	if (!node)
86 		return -ENOMEM;
87 
88 	ether_addr_copy(node->macaddress_A, addr_a);
89 	ether_addr_copy(node->macaddress_B, addr_b);
90 
91 	spin_lock_bh(&hsr->list_lock);
92 	oldnode = list_first_or_null_rcu(self_node_db,
93 					 struct hsr_node, mac_list);
94 	if (oldnode) {
95 		list_replace_rcu(&oldnode->mac_list, &node->mac_list);
96 		spin_unlock_bh(&hsr->list_lock);
97 		kfree_rcu(oldnode, rcu_head);
98 	} else {
99 		list_add_tail_rcu(&node->mac_list, self_node_db);
100 		spin_unlock_bh(&hsr->list_lock);
101 	}
102 
103 	return 0;
104 }
105 
106 void hsr_del_self_node(struct hsr_priv *hsr)
107 {
108 	struct list_head *self_node_db = &hsr->self_node_db;
109 	struct hsr_node *node;
110 
111 	spin_lock_bh(&hsr->list_lock);
112 	node = list_first_or_null_rcu(self_node_db, struct hsr_node, mac_list);
113 	if (node) {
114 		list_del_rcu(&node->mac_list);
115 		kfree_rcu(node, rcu_head);
116 	}
117 	spin_unlock_bh(&hsr->list_lock);
118 }
119 
120 void hsr_del_nodes(struct list_head *node_db)
121 {
122 	struct hsr_node *node;
123 	struct hsr_node *tmp;
124 
125 	list_for_each_entry_safe(node, tmp, node_db, mac_list)
126 		kfree(node);
127 }
128 
129 /* Allocate an hsr_node and add it to node_db. 'addr' is the node's address_A;
130  * seq_out is used to initialize filtering of outgoing duplicate frames
131  * originating from the newly added node.
132  */
133 static struct hsr_node *hsr_add_node(struct hsr_priv *hsr,
134 				     struct list_head *node_db,
135 				     unsigned char addr[],
136 				     u16 seq_out)
137 {
138 	struct hsr_node *new_node, *node;
139 	unsigned long now;
140 	int i;
141 
142 	new_node = kzalloc(sizeof(*new_node), GFP_ATOMIC);
143 	if (!new_node)
144 		return NULL;
145 
146 	ether_addr_copy(new_node->macaddress_A, addr);
147 
148 	/* We are only interested in time diffs here, so use current jiffies
149 	 * as initialization. (0 could trigger an spurious ring error warning).
150 	 */
151 	now = jiffies;
152 	for (i = 0; i < HSR_PT_PORTS; i++)
153 		new_node->time_in[i] = now;
154 	for (i = 0; i < HSR_PT_PORTS; i++)
155 		new_node->seq_out[i] = seq_out;
156 
157 	spin_lock_bh(&hsr->list_lock);
158 	list_for_each_entry_rcu(node, node_db, mac_list,
159 				lockdep_is_held(&hsr->list_lock)) {
160 		if (ether_addr_equal(node->macaddress_A, addr))
161 			goto out;
162 		if (ether_addr_equal(node->macaddress_B, addr))
163 			goto out;
164 	}
165 	list_add_tail_rcu(&new_node->mac_list, node_db);
166 	spin_unlock_bh(&hsr->list_lock);
167 	return new_node;
168 out:
169 	spin_unlock_bh(&hsr->list_lock);
170 	kfree(new_node);
171 	return node;
172 }
173 
174 /* Get the hsr_node from which 'skb' was sent.
175  */
176 struct hsr_node *hsr_get_node(struct hsr_port *port, struct sk_buff *skb,
177 			      bool is_sup)
178 {
179 	struct list_head *node_db = &port->hsr->node_db;
180 	struct hsr_priv *hsr = port->hsr;
181 	struct hsr_node *node;
182 	struct ethhdr *ethhdr;
183 	u16 seq_out;
184 
185 	if (!skb_mac_header_was_set(skb))
186 		return NULL;
187 
188 	ethhdr = (struct ethhdr *)skb_mac_header(skb);
189 
190 	list_for_each_entry_rcu(node, node_db, mac_list) {
191 		if (ether_addr_equal(node->macaddress_A, ethhdr->h_source))
192 			return node;
193 		if (ether_addr_equal(node->macaddress_B, ethhdr->h_source))
194 			return node;
195 	}
196 
197 	/* Everyone may create a node entry, connected node to a HSR device. */
198 
199 	if (ethhdr->h_proto == htons(ETH_P_PRP) ||
200 	    ethhdr->h_proto == htons(ETH_P_HSR)) {
201 		/* Use the existing sequence_nr from the tag as starting point
202 		 * for filtering duplicate frames.
203 		 */
204 		seq_out = hsr_get_skb_sequence_nr(skb) - 1;
205 	} else {
206 		/* this is called also for frames from master port and
207 		 * so warn only for non master ports
208 		 */
209 		if (port->type != HSR_PT_MASTER)
210 			WARN_ONCE(1, "%s: Non-HSR frame\n", __func__);
211 		seq_out = HSR_SEQNR_START;
212 	}
213 
214 	return hsr_add_node(hsr, node_db, ethhdr->h_source, seq_out);
215 }
216 
217 /* Use the Supervision frame's info about an eventual macaddress_B for merging
218  * nodes that has previously had their macaddress_B registered as a separate
219  * node.
220  */
221 void hsr_handle_sup_frame(struct sk_buff *skb, struct hsr_node *node_curr,
222 			  struct hsr_port *port_rcv)
223 {
224 	struct hsr_priv *hsr = port_rcv->hsr;
225 	struct hsr_sup_payload *hsr_sp;
226 	struct hsr_node *node_real;
227 	struct list_head *node_db;
228 	struct ethhdr *ethhdr;
229 	int i;
230 
231 	ethhdr = (struct ethhdr *)skb_mac_header(skb);
232 
233 	/* Leave the ethernet header. */
234 	skb_pull(skb, sizeof(struct ethhdr));
235 
236 	/* And leave the HSR tag. */
237 	if (ethhdr->h_proto == htons(ETH_P_HSR))
238 		skb_pull(skb, sizeof(struct hsr_tag));
239 
240 	/* And leave the HSR sup tag. */
241 	skb_pull(skb, sizeof(struct hsr_sup_tag));
242 
243 	hsr_sp = (struct hsr_sup_payload *)skb->data;
244 
245 	/* Merge node_curr (registered on macaddress_B) into node_real */
246 	node_db = &port_rcv->hsr->node_db;
247 	node_real = find_node_by_addr_A(node_db, hsr_sp->macaddress_A);
248 	if (!node_real)
249 		/* No frame received from AddrA of this node yet */
250 		node_real = hsr_add_node(hsr, node_db, hsr_sp->macaddress_A,
251 					 HSR_SEQNR_START - 1);
252 	if (!node_real)
253 		goto done; /* No mem */
254 	if (node_real == node_curr)
255 		/* Node has already been merged */
256 		goto done;
257 
258 	ether_addr_copy(node_real->macaddress_B, ethhdr->h_source);
259 	for (i = 0; i < HSR_PT_PORTS; i++) {
260 		if (!node_curr->time_in_stale[i] &&
261 		    time_after(node_curr->time_in[i], node_real->time_in[i])) {
262 			node_real->time_in[i] = node_curr->time_in[i];
263 			node_real->time_in_stale[i] =
264 						node_curr->time_in_stale[i];
265 		}
266 		if (seq_nr_after(node_curr->seq_out[i], node_real->seq_out[i]))
267 			node_real->seq_out[i] = node_curr->seq_out[i];
268 	}
269 	node_real->addr_B_port = port_rcv->type;
270 
271 	spin_lock_bh(&hsr->list_lock);
272 	list_del_rcu(&node_curr->mac_list);
273 	spin_unlock_bh(&hsr->list_lock);
274 	kfree_rcu(node_curr, rcu_head);
275 
276 done:
277 	skb_push(skb, sizeof(struct hsrv1_ethhdr_sp));
278 }
279 
280 /* 'skb' is a frame meant for this host, that is to be passed to upper layers.
281  *
282  * If the frame was sent by a node's B interface, replace the source
283  * address with that node's "official" address (macaddress_A) so that upper
284  * layers recognize where it came from.
285  */
286 void hsr_addr_subst_source(struct hsr_node *node, struct sk_buff *skb)
287 {
288 	if (!skb_mac_header_was_set(skb)) {
289 		WARN_ONCE(1, "%s: Mac header not set\n", __func__);
290 		return;
291 	}
292 
293 	memcpy(&eth_hdr(skb)->h_source, node->macaddress_A, ETH_ALEN);
294 }
295 
296 /* 'skb' is a frame meant for another host.
297  * 'port' is the outgoing interface
298  *
299  * Substitute the target (dest) MAC address if necessary, so the it matches the
300  * recipient interface MAC address, regardless of whether that is the
301  * recipient's A or B interface.
302  * This is needed to keep the packets flowing through switches that learn on
303  * which "side" the different interfaces are.
304  */
305 void hsr_addr_subst_dest(struct hsr_node *node_src, struct sk_buff *skb,
306 			 struct hsr_port *port)
307 {
308 	struct hsr_node *node_dst;
309 
310 	if (!skb_mac_header_was_set(skb)) {
311 		WARN_ONCE(1, "%s: Mac header not set\n", __func__);
312 		return;
313 	}
314 
315 	if (!is_unicast_ether_addr(eth_hdr(skb)->h_dest))
316 		return;
317 
318 	node_dst = find_node_by_addr_A(&port->hsr->node_db,
319 				       eth_hdr(skb)->h_dest);
320 	if (!node_dst) {
321 		WARN_ONCE(1, "%s: Unknown node\n", __func__);
322 		return;
323 	}
324 	if (port->type != node_dst->addr_B_port)
325 		return;
326 
327 	ether_addr_copy(eth_hdr(skb)->h_dest, node_dst->macaddress_B);
328 }
329 
330 void hsr_register_frame_in(struct hsr_node *node, struct hsr_port *port,
331 			   u16 sequence_nr)
332 {
333 	/* Don't register incoming frames without a valid sequence number. This
334 	 * ensures entries of restarted nodes gets pruned so that they can
335 	 * re-register and resume communications.
336 	 */
337 	if (seq_nr_before(sequence_nr, node->seq_out[port->type]))
338 		return;
339 
340 	node->time_in[port->type] = jiffies;
341 	node->time_in_stale[port->type] = false;
342 }
343 
344 /* 'skb' is a HSR Ethernet frame (with a HSR tag inserted), with a valid
345  * ethhdr->h_source address and skb->mac_header set.
346  *
347  * Return:
348  *	 1 if frame can be shown to have been sent recently on this interface,
349  *	 0 otherwise, or
350  *	 negative error code on error
351  */
352 int hsr_register_frame_out(struct hsr_port *port, struct hsr_node *node,
353 			   u16 sequence_nr)
354 {
355 	if (seq_nr_before_or_eq(sequence_nr, node->seq_out[port->type]))
356 		return 1;
357 
358 	node->seq_out[port->type] = sequence_nr;
359 	return 0;
360 }
361 
362 static struct hsr_port *get_late_port(struct hsr_priv *hsr,
363 				      struct hsr_node *node)
364 {
365 	if (node->time_in_stale[HSR_PT_SLAVE_A])
366 		return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_A);
367 	if (node->time_in_stale[HSR_PT_SLAVE_B])
368 		return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B);
369 
370 	if (time_after(node->time_in[HSR_PT_SLAVE_B],
371 		       node->time_in[HSR_PT_SLAVE_A] +
372 					msecs_to_jiffies(MAX_SLAVE_DIFF)))
373 		return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_A);
374 	if (time_after(node->time_in[HSR_PT_SLAVE_A],
375 		       node->time_in[HSR_PT_SLAVE_B] +
376 					msecs_to_jiffies(MAX_SLAVE_DIFF)))
377 		return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B);
378 
379 	return NULL;
380 }
381 
382 /* Remove stale sequence_nr records. Called by timer every
383  * HSR_LIFE_CHECK_INTERVAL (two seconds or so).
384  */
385 void hsr_prune_nodes(struct timer_list *t)
386 {
387 	struct hsr_priv *hsr = from_timer(hsr, t, prune_timer);
388 	struct hsr_node *node;
389 	struct hsr_node *tmp;
390 	struct hsr_port *port;
391 	unsigned long timestamp;
392 	unsigned long time_a, time_b;
393 
394 	spin_lock_bh(&hsr->list_lock);
395 	list_for_each_entry_safe(node, tmp, &hsr->node_db, mac_list) {
396 		/* Don't prune own node. Neither time_in[HSR_PT_SLAVE_A]
397 		 * nor time_in[HSR_PT_SLAVE_B], will ever be updated for
398 		 * the master port. Thus the master node will be repeatedly
399 		 * pruned leading to packet loss.
400 		 */
401 		if (hsr_addr_is_self(hsr, node->macaddress_A))
402 			continue;
403 
404 		/* Shorthand */
405 		time_a = node->time_in[HSR_PT_SLAVE_A];
406 		time_b = node->time_in[HSR_PT_SLAVE_B];
407 
408 		/* Check for timestamps old enough to risk wrap-around */
409 		if (time_after(jiffies, time_a + MAX_JIFFY_OFFSET / 2))
410 			node->time_in_stale[HSR_PT_SLAVE_A] = true;
411 		if (time_after(jiffies, time_b + MAX_JIFFY_OFFSET / 2))
412 			node->time_in_stale[HSR_PT_SLAVE_B] = true;
413 
414 		/* Get age of newest frame from node.
415 		 * At least one time_in is OK here; nodes get pruned long
416 		 * before both time_ins can get stale
417 		 */
418 		timestamp = time_a;
419 		if (node->time_in_stale[HSR_PT_SLAVE_A] ||
420 		    (!node->time_in_stale[HSR_PT_SLAVE_B] &&
421 		    time_after(time_b, time_a)))
422 			timestamp = time_b;
423 
424 		/* Warn of ring error only as long as we get frames at all */
425 		if (time_is_after_jiffies(timestamp +
426 				msecs_to_jiffies(1.5 * MAX_SLAVE_DIFF))) {
427 			rcu_read_lock();
428 			port = get_late_port(hsr, node);
429 			if (port)
430 				hsr_nl_ringerror(hsr, node->macaddress_A, port);
431 			rcu_read_unlock();
432 		}
433 
434 		/* Prune old entries */
435 		if (time_is_before_jiffies(timestamp +
436 				msecs_to_jiffies(HSR_NODE_FORGET_TIME))) {
437 			hsr_nl_nodedown(hsr, node->macaddress_A);
438 			list_del_rcu(&node->mac_list);
439 			/* Note that we need to free this entry later: */
440 			kfree_rcu(node, rcu_head);
441 		}
442 	}
443 	spin_unlock_bh(&hsr->list_lock);
444 
445 	/* Restart timer */
446 	mod_timer(&hsr->prune_timer,
447 		  jiffies + msecs_to_jiffies(PRUNE_PERIOD));
448 }
449 
450 void *hsr_get_next_node(struct hsr_priv *hsr, void *_pos,
451 			unsigned char addr[ETH_ALEN])
452 {
453 	struct hsr_node *node;
454 
455 	if (!_pos) {
456 		node = list_first_or_null_rcu(&hsr->node_db,
457 					      struct hsr_node, mac_list);
458 		if (node)
459 			ether_addr_copy(addr, node->macaddress_A);
460 		return node;
461 	}
462 
463 	node = _pos;
464 	list_for_each_entry_continue_rcu(node, &hsr->node_db, mac_list) {
465 		ether_addr_copy(addr, node->macaddress_A);
466 		return node;
467 	}
468 
469 	return NULL;
470 }
471 
472 int hsr_get_node_data(struct hsr_priv *hsr,
473 		      const unsigned char *addr,
474 		      unsigned char addr_b[ETH_ALEN],
475 		      unsigned int *addr_b_ifindex,
476 		      int *if1_age,
477 		      u16 *if1_seq,
478 		      int *if2_age,
479 		      u16 *if2_seq)
480 {
481 	struct hsr_node *node;
482 	struct hsr_port *port;
483 	unsigned long tdiff;
484 
485 	rcu_read_lock();
486 	node = find_node_by_addr_A(&hsr->node_db, addr);
487 	if (!node) {
488 		rcu_read_unlock();
489 		return -ENOENT;	/* No such entry */
490 	}
491 
492 	ether_addr_copy(addr_b, node->macaddress_B);
493 
494 	tdiff = jiffies - node->time_in[HSR_PT_SLAVE_A];
495 	if (node->time_in_stale[HSR_PT_SLAVE_A])
496 		*if1_age = INT_MAX;
497 #if HZ <= MSEC_PER_SEC
498 	else if (tdiff > msecs_to_jiffies(INT_MAX))
499 		*if1_age = INT_MAX;
500 #endif
501 	else
502 		*if1_age = jiffies_to_msecs(tdiff);
503 
504 	tdiff = jiffies - node->time_in[HSR_PT_SLAVE_B];
505 	if (node->time_in_stale[HSR_PT_SLAVE_B])
506 		*if2_age = INT_MAX;
507 #if HZ <= MSEC_PER_SEC
508 	else if (tdiff > msecs_to_jiffies(INT_MAX))
509 		*if2_age = INT_MAX;
510 #endif
511 	else
512 		*if2_age = jiffies_to_msecs(tdiff);
513 
514 	/* Present sequence numbers as if they were incoming on interface */
515 	*if1_seq = node->seq_out[HSR_PT_SLAVE_B];
516 	*if2_seq = node->seq_out[HSR_PT_SLAVE_A];
517 
518 	if (node->addr_B_port != HSR_PT_NONE) {
519 		port = hsr_port_get_hsr(hsr, node->addr_B_port);
520 		*addr_b_ifindex = port->dev->ifindex;
521 	} else {
522 		*addr_b_ifindex = -1;
523 	}
524 
525 	rcu_read_unlock();
526 
527 	return 0;
528 }
529