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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 
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  */
132 struct 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  */
161 struct 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  */
200 void 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 
243 done:
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  */
254 void 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  */
273 void 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 
298 void 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  */
320 int 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 
331 static 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  */
355 void 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 
410 void *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 
433 int 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 

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