net/hsr/hsr_framereg.c

   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 }