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

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