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Linux/net/hsr/hsr_framereg.c

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  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 
 26 struct 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  */
 45 static 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 
 60 bool 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  */
 81 static 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  */
 98 int 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 void hsr_del_node(struct list_head *self_node_db)
128 {
129         struct hsr_node *node;
130 
131         rcu_read_lock();
132         node = list_first_or_null_rcu(self_node_db, struct hsr_node, mac_list);
133         rcu_read_unlock();
134         if (node) {
135                 list_del_rcu(&node->mac_list);
136                 kfree(node);
137         }
138 }
139 
140 /* Allocate an hsr_node and add it to node_db. 'addr' is the node's AddressA;
141  * seq_out is used to initialize filtering of outgoing duplicate frames
142  * originating from the newly added node.
143  */
144 struct hsr_node *hsr_add_node(struct list_head *node_db, unsigned char addr[],
145                               u16 seq_out)
146 {
147         struct hsr_node *node;
148         unsigned long now;
149         int i;
150 
151         node = kzalloc(sizeof(*node), GFP_ATOMIC);
152         if (!node)
153                 return NULL;
154 
155         ether_addr_copy(node->MacAddressA, addr);
156 
157         /* We are only interested in time diffs here, so use current jiffies
158          * as initialization. (0 could trigger an spurious ring error warning).
159          */
160         now = jiffies;
161         for (i = 0; i < HSR_PT_PORTS; i++)
162                 node->time_in[i] = now;
163         for (i = 0; i < HSR_PT_PORTS; i++)
164                 node->seq_out[i] = seq_out;
165 
166         list_add_tail_rcu(&node->mac_list, node_db);
167 
168         return node;
169 }
170 
171 /* Get the hsr_node from which 'skb' was sent.
172  */
173 struct hsr_node *hsr_get_node(struct hsr_port *port, struct sk_buff *skb,
174                               bool is_sup)
175 {
176         struct list_head *node_db = &port->hsr->node_db;
177         struct hsr_node *node;
178         struct ethhdr *ethhdr;
179         u16 seq_out;
180 
181         if (!skb_mac_header_was_set(skb))
182                 return NULL;
183 
184         ethhdr = (struct ethhdr *) skb_mac_header(skb);
185 
186         list_for_each_entry_rcu(node, node_db, mac_list) {
187                 if (ether_addr_equal(node->MacAddressA, ethhdr->h_source))
188                         return node;
189                 if (ether_addr_equal(node->MacAddressB, ethhdr->h_source))
190                         return node;
191         }
192 
193         /* Everyone may create a node entry, connected node to a HSR device. */
194 
195         if (ethhdr->h_proto == htons(ETH_P_PRP)
196                         || ethhdr->h_proto == htons(ETH_P_HSR)) {
197                 /* Use the existing sequence_nr from the tag as starting point
198                  * for filtering duplicate frames.
199                  */
200                 seq_out = hsr_get_skb_sequence_nr(skb) - 1;
201         } else {
202                 /* this is called also for frames from master port and
203                  * so warn only for non master ports
204                  */
205                 if (port->type != HSR_PT_MASTER)
206                         WARN_ONCE(1, "%s: Non-HSR frame\n", __func__);
207                 seq_out = HSR_SEQNR_START;
208         }
209 
210         return hsr_add_node(node_db, ethhdr->h_source, seq_out);
211 }
212 
213 /* Use the Supervision frame's info about an eventual MacAddressB for merging
214  * nodes that has previously had their MacAddressB registered as a separate
215  * node.
216  */
217 void hsr_handle_sup_frame(struct sk_buff *skb, struct hsr_node *node_curr,
218                           struct hsr_port *port_rcv)
219 {
220         struct ethhdr *ethhdr;
221         struct hsr_node *node_real;
222         struct hsr_sup_payload *hsr_sp;
223         struct list_head *node_db;
224         int i;
225 
226         ethhdr = (struct ethhdr *) skb_mac_header(skb);
227 
228         /* Leave the ethernet header. */
229         skb_pull(skb, sizeof(struct ethhdr));
230 
231         /* And leave the HSR tag. */
232         if (ethhdr->h_proto == htons(ETH_P_HSR))
233                 skb_pull(skb, sizeof(struct hsr_tag));
234 
235         /* And leave the HSR sup tag. */
236         skb_pull(skb, sizeof(struct hsr_sup_tag));
237 
238         hsr_sp = (struct hsr_sup_payload *) skb->data;
239 
240         /* Merge node_curr (registered on MacAddressB) into node_real */
241         node_db = &port_rcv->hsr->node_db;
242         node_real = find_node_by_AddrA(node_db, hsr_sp->MacAddressA);
243         if (!node_real)
244                 /* No frame received from AddrA of this node yet */
245                 node_real = hsr_add_node(node_db, hsr_sp->MacAddressA,
246                                          HSR_SEQNR_START - 1);
247         if (!node_real)
248                 goto done; /* No mem */
249         if (node_real == node_curr)
250                 /* Node has already been merged */
251                 goto done;
252 
253         ether_addr_copy(node_real->MacAddressB, ethhdr->h_source);
254         for (i = 0; i < HSR_PT_PORTS; i++) {
255                 if (!node_curr->time_in_stale[i] &&
256                     time_after(node_curr->time_in[i], node_real->time_in[i])) {
257                         node_real->time_in[i] = node_curr->time_in[i];
258                         node_real->time_in_stale[i] = node_curr->time_in_stale[i];
259                 }
260                 if (seq_nr_after(node_curr->seq_out[i], node_real->seq_out[i]))
261                         node_real->seq_out[i] = node_curr->seq_out[i];
262         }
263         node_real->AddrB_port = port_rcv->type;
264 
265         list_del_rcu(&node_curr->mac_list);
266         kfree_rcu(node_curr, rcu_head);
267 
268 done:
269         skb_push(skb, sizeof(struct hsrv1_ethhdr_sp));
270 }
271 
272 
273 /* 'skb' is a frame meant for this host, that is to be passed to upper layers.
274  *
275  * If the frame was sent by a node's B interface, replace the source
276  * address with that node's "official" address (MacAddressA) so that upper
277  * layers recognize where it came from.
278  */
279 void hsr_addr_subst_source(struct hsr_node *node, struct sk_buff *skb)
280 {
281         if (!skb_mac_header_was_set(skb)) {
282                 WARN_ONCE(1, "%s: Mac header not set\n", __func__);
283                 return;
284         }
285 
286         memcpy(&eth_hdr(skb)->h_source, node->MacAddressA, ETH_ALEN);
287 }
288 
289 /* 'skb' is a frame meant for another host.
290  * 'port' is the outgoing interface
291  *
292  * Substitute the target (dest) MAC address if necessary, so the it matches the
293  * recipient interface MAC address, regardless of whether that is the
294  * recipient's A or B interface.
295  * This is needed to keep the packets flowing through switches that learn on
296  * which "side" the different interfaces are.
297  */
298 void hsr_addr_subst_dest(struct hsr_node *node_src, struct sk_buff *skb,
299                          struct hsr_port *port)
300 {
301         struct hsr_node *node_dst;
302 
303         if (!skb_mac_header_was_set(skb)) {
304                 WARN_ONCE(1, "%s: Mac header not set\n", __func__);
305                 return;
306         }
307 
308         if (!is_unicast_ether_addr(eth_hdr(skb)->h_dest))
309                 return;
310 
311         node_dst = find_node_by_AddrA(&port->hsr->node_db, eth_hdr(skb)->h_dest);
312         if (!node_dst) {
313                 WARN_ONCE(1, "%s: Unknown node\n", __func__);
314                 return;
315         }
316         if (port->type != node_dst->AddrB_port)
317                 return;
318 
319         ether_addr_copy(eth_hdr(skb)->h_dest, node_dst->MacAddressB);
320 }
321 
322 
323 void hsr_register_frame_in(struct hsr_node *node, struct hsr_port *port,
324                            u16 sequence_nr)
325 {
326         /* Don't register incoming frames without a valid sequence number. This
327          * ensures entries of restarted nodes gets pruned so that they can
328          * re-register and resume communications.
329          */
330         if (seq_nr_before(sequence_nr, node->seq_out[port->type]))
331                 return;
332 
333         node->time_in[port->type] = jiffies;
334         node->time_in_stale[port->type] = false;
335 }
336 
337 /* 'skb' is a HSR Ethernet frame (with a HSR tag inserted), with a valid
338  * ethhdr->h_source address and skb->mac_header set.
339  *
340  * Return:
341  *       1 if frame can be shown to have been sent recently on this interface,
342  *       0 otherwise, or
343  *       negative error code on error
344  */
345 int hsr_register_frame_out(struct hsr_port *port, struct hsr_node *node,
346                            u16 sequence_nr)
347 {
348         if (seq_nr_before_or_eq(sequence_nr, node->seq_out[port->type]))
349                 return 1;
350 
351         node->seq_out[port->type] = sequence_nr;
352         return 0;
353 }
354 
355 
356 static struct hsr_port *get_late_port(struct hsr_priv *hsr,
357                                       struct hsr_node *node)
358 {
359         if (node->time_in_stale[HSR_PT_SLAVE_A])
360                 return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_A);
361         if (node->time_in_stale[HSR_PT_SLAVE_B])
362                 return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B);
363 
364         if (time_after(node->time_in[HSR_PT_SLAVE_B],
365                        node->time_in[HSR_PT_SLAVE_A] +
366                                         msecs_to_jiffies(MAX_SLAVE_DIFF)))
367                 return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_A);
368         if (time_after(node->time_in[HSR_PT_SLAVE_A],
369                        node->time_in[HSR_PT_SLAVE_B] +
370                                         msecs_to_jiffies(MAX_SLAVE_DIFF)))
371                 return hsr_port_get_hsr(hsr, HSR_PT_SLAVE_B);
372 
373         return NULL;
374 }
375 
376 
377 /* Remove stale sequence_nr records. Called by timer every
378  * HSR_LIFE_CHECK_INTERVAL (two seconds or so).
379  */
380 void hsr_prune_nodes(struct timer_list *t)
381 {
382         struct hsr_priv *hsr = from_timer(hsr, t, prune_timer);
383         struct hsr_node *node;
384         struct hsr_port *port;
385         unsigned long timestamp;
386         unsigned long time_a, time_b;
387 
388         rcu_read_lock();
389         list_for_each_entry_rcu(node, &hsr->node_db, mac_list) {
390                 /* Shorthand */
391                 time_a = node->time_in[HSR_PT_SLAVE_A];
392                 time_b = node->time_in[HSR_PT_SLAVE_B];
393 
394                 /* Check for timestamps old enough to risk wrap-around */
395                 if (time_after(jiffies, time_a + MAX_JIFFY_OFFSET/2))
396                         node->time_in_stale[HSR_PT_SLAVE_A] = true;
397                 if (time_after(jiffies, time_b + MAX_JIFFY_OFFSET/2))
398                         node->time_in_stale[HSR_PT_SLAVE_B] = true;
399 
400                 /* Get age of newest frame from node.
401                  * At least one time_in is OK here; nodes get pruned long
402                  * before both time_ins can get stale
403                  */
404                 timestamp = time_a;
405                 if (node->time_in_stale[HSR_PT_SLAVE_A] ||
406                     (!node->time_in_stale[HSR_PT_SLAVE_B] &&
407                     time_after(time_b, time_a)))
408                         timestamp = time_b;
409 
410                 /* Warn of ring error only as long as we get frames at all */
411                 if (time_is_after_jiffies(timestamp +
412                                         msecs_to_jiffies(1.5*MAX_SLAVE_DIFF))) {
413                         rcu_read_lock();
414                         port = get_late_port(hsr, node);
415                         if (port != NULL)
416                                 hsr_nl_ringerror(hsr, node->MacAddressA, port);
417                         rcu_read_unlock();
418                 }
419 
420                 /* Prune old entries */
421                 if (time_is_before_jiffies(timestamp +
422                                         msecs_to_jiffies(HSR_NODE_FORGET_TIME))) {
423                         hsr_nl_nodedown(hsr, node->MacAddressA);
424                         list_del_rcu(&node->mac_list);
425                         /* Note that we need to free this entry later: */
426                         kfree_rcu(node, rcu_head);
427                 }
428         }
429         rcu_read_unlock();
430 }
431 
432 
433 void *hsr_get_next_node(struct hsr_priv *hsr, void *_pos,
434                         unsigned char addr[ETH_ALEN])
435 {
436         struct hsr_node *node;
437 
438         if (!_pos) {
439                 node = list_first_or_null_rcu(&hsr->node_db,
440                                               struct hsr_node, mac_list);
441                 if (node)
442                         ether_addr_copy(addr, node->MacAddressA);
443                 return node;
444         }
445 
446         node = _pos;
447         list_for_each_entry_continue_rcu(node, &hsr->node_db, mac_list) {
448                 ether_addr_copy(addr, node->MacAddressA);
449                 return node;
450         }
451 
452         return NULL;
453 }
454 
455 
456 int hsr_get_node_data(struct hsr_priv *hsr,
457                       const unsigned char *addr,
458                       unsigned char addr_b[ETH_ALEN],
459                       unsigned int *addr_b_ifindex,
460                       int *if1_age,
461                       u16 *if1_seq,
462                       int *if2_age,
463                       u16 *if2_seq)
464 {
465         struct hsr_node *node;
466         struct hsr_port *port;
467         unsigned long tdiff;
468 
469 
470         rcu_read_lock();
471         node = find_node_by_AddrA(&hsr->node_db, addr);
472         if (!node) {
473                 rcu_read_unlock();
474                 return -ENOENT; /* No such entry */
475         }
476 
477         ether_addr_copy(addr_b, node->MacAddressB);
478 
479         tdiff = jiffies - node->time_in[HSR_PT_SLAVE_A];
480         if (node->time_in_stale[HSR_PT_SLAVE_A])
481                 *if1_age = INT_MAX;
482 #if HZ <= MSEC_PER_SEC
483         else if (tdiff > msecs_to_jiffies(INT_MAX))
484                 *if1_age = INT_MAX;
485 #endif
486         else
487                 *if1_age = jiffies_to_msecs(tdiff);
488 
489         tdiff = jiffies - node->time_in[HSR_PT_SLAVE_B];
490         if (node->time_in_stale[HSR_PT_SLAVE_B])
491                 *if2_age = INT_MAX;
492 #if HZ <= MSEC_PER_SEC
493         else if (tdiff > msecs_to_jiffies(INT_MAX))
494                 *if2_age = INT_MAX;
495 #endif
496         else
497                 *if2_age = jiffies_to_msecs(tdiff);
498 
499         /* Present sequence numbers as if they were incoming on interface */
500         *if1_seq = node->seq_out[HSR_PT_SLAVE_B];
501         *if2_seq = node->seq_out[HSR_PT_SLAVE_A];
502 
503         if (node->AddrB_port != HSR_PT_NONE) {
504                 port = hsr_port_get_hsr(hsr, node->AddrB_port);
505                 *addr_b_ifindex = port->dev->ifindex;
506         } else {
507                 *addr_b_ifindex = -1;
508         }
509 
510         rcu_read_unlock();
511 
512         return 0;
513 }
514 

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