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