net/mac80211/mesh_pathtbl.c

   1 /*
   2  * Copyright (c) 2008 open80211s Ltd.
   3  * Author:     Luis Carlos Cobo <luisca@cozybit.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/etherdevice.h>
  11 #include <linux/list.h>
  12 #include <linux/netdevice.h>
  13 #include <linux/random.h>
  14 #include <linux/spinlock.h>
  15 #include <linux/string.h>
  16 #include <net/mac80211.h>
  17 #include "ieee80211_i.h"
  18 #include "mesh.h"
  19
  20 /* There will be initially 2^INIT_PATHS_SIZE_ORDER buckets */
  21 #define INIT_PATHS_SIZE_ORDER   2
  22
  23 /* Keep the mean chain length below this constant */
  24 #define MEAN_CHAIN_LEN          2
  25
  26 #define MPATH_EXPIRED(mpath) ((mpath->flags & MESH_PATH_ACTIVE) && \
  27                                 time_after(jiffies, mpath->exp_time) && \
  28                                 !(mpath->flags & MESH_PATH_FIXED))
  29
  30 struct mpath_node {
  31         struct hlist_node list;
  32         struct rcu_head rcu;
  33         /* This indirection allows two different tables to point to the same
  34          * mesh_path structure, useful when resizing
  35          */
  36         struct mesh_path *mpath;
  37 };
  38
  39 static struct mesh_table *mesh_paths;
  40
  41 /* This lock will have the grow table function as writer and add / delete nodes
  42  * as readers. When reading the table (i.e. doing lookups) we are well protected
  43  * by RCU
  44  */
  45 static DEFINE_RWLOCK(pathtbl_resize_lock);
  46
  47 /**
  48  *
  49  * mesh_path_assign_nexthop - update mesh path next hop
  50  *
  51  * @mpath: mesh path to update
  52  * @sta: next hop to assign
  53  *
  54  * Locking: mpath->state_lock must be held when calling this function
  55  */
  56 void mesh_path_assign_nexthop(struct mesh_path *mpath, struct sta_info *sta)
  57 {
  58         rcu_assign_pointer(mpath->next_hop, sta);
  59 }
  60
  61
  62 /**
  63  * mesh_path_lookup - look up a path in the mesh path table
  64  * @dst: hardware address (ETH_ALEN length) of destination
  65  * @dev: local interface
  66  *
  67  * Returns: pointer to the mesh path structure, or NULL if not found
  68  *
  69  * Locking: must be called within a read rcu section.
  70  */
  71 struct mesh_path *mesh_path_lookup(u8 *dst, struct net_device *dev)
  72 {
  73         struct mesh_path *mpath;
  74         struct hlist_node *n;
  75         struct hlist_head *bucket;
  76         struct mesh_table *tbl;
  77         struct mpath_node *node;
  78
  79         tbl = rcu_dereference(mesh_paths);
  80
  81         bucket = &tbl->hash_buckets[mesh_table_hash(dst, dev, tbl)];
  82         hlist_for_each_entry_rcu(node, n, bucket, list) {
  83                 mpath = node->mpath;
  84                 if (mpath->dev == dev &&
  85                                 memcmp(dst, mpath->dst, ETH_ALEN) == 0) {
  86                         if (MPATH_EXPIRED(mpath)) {
  87                                 spin_lock_bh(&mpath->state_lock);
  88                                 if (MPATH_EXPIRED(mpath))
  89                                         mpath->flags &= ~MESH_PATH_ACTIVE;
  90                                 spin_unlock_bh(&mpath->state_lock);
  91                         }
  92                         return mpath;
  93                 }
  94         }
  95         return NULL;
  96 }
  97
  98 /**
  99  * mesh_path_lookup_by_idx - look up a path in the mesh path table by its index
 100  * @idx: index
 101  * @dev: local interface
 102  *
 103  * Returns: pointer to the mesh path structure, or NULL if not found.
 104  *
 105  * Locking: must be called within a read rcu section.
 106  */
 107 struct mesh_path *mesh_path_lookup_by_idx(int idx, struct net_device *dev)
 108 {
 109         struct mpath_node *node;
 110         struct hlist_node *p;
 111         int i;
 112         int j = 0;
 113
 114         for_each_mesh_entry(mesh_paths, p, node, i)
 115                 if (j++ == idx) {
 116                         if (MPATH_EXPIRED(node->mpath)) {
 117                                 spin_lock_bh(&node->mpath->state_lock);
 118                                 if (MPATH_EXPIRED(node->mpath))
 119                                         node->mpath->flags &= ~MESH_PATH_ACTIVE;
 120                                 spin_unlock_bh(&node->mpath->state_lock);
 121                         }
 122                         return node->mpath;
 123                 }
 124
 125         return NULL;
 126 }
 127
 128 /**
 129  * mesh_path_add - allocate and add a new path to the mesh path table
 130  * @addr: destination address of the path (ETH_ALEN length)
 131  * @dev: local interface
 132  *
 133  * Returns: 0 on sucess
 134  *
 135  * State: the initial state of the new path is set to 0
 136  */
 137 int mesh_path_add(u8 *dst, struct net_device *dev)
 138 {
 139         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 140         struct mesh_path *mpath, *new_mpath;
 141         struct mpath_node *node, *new_node;
 142         struct hlist_head *bucket;
 143         struct hlist_node *n;
 144         int grow = 0;
 145         int err = 0;
 146         u32 hash_idx;
 147
 148         if (memcmp(dst, dev->dev_addr, ETH_ALEN) == 0)
 149                 /* never add ourselves as neighbours */
 150                 return -ENOTSUPP;
 151
 152         if (is_multicast_ether_addr(dst))
 153                 return -ENOTSUPP;
 154
 155         if (atomic_add_unless(&sdata->u.sta.mpaths, 1, MESH_MAX_MPATHS) == 0)
 156                 return -ENOSPC;
 157
 158         read_lock(&pathtbl_resize_lock);
 159
 160         new_mpath = kzalloc(sizeof(struct mesh_path), GFP_KERNEL);
 161         if (!new_mpath) {
 162                 atomic_dec(&sdata->u.sta.mpaths);
 163                 err = -ENOMEM;
 164                 goto endadd2;
 165         }
 166         memcpy(new_mpath->dst, dst, ETH_ALEN);
 167         new_mpath->dev = dev;
 168         new_mpath->flags = 0;
 169         skb_queue_head_init(&new_mpath->frame_queue);
 170         new_node = kmalloc(sizeof(struct mpath_node), GFP_KERNEL);
 171         new_node->mpath = new_mpath;
 172         new_mpath->timer.data = (unsigned long) new_mpath;
 173         new_mpath->timer.function = mesh_path_timer;
 174         new_mpath->exp_time = jiffies;
 175         spin_lock_init(&new_mpath->state_lock);
 176         init_timer(&new_mpath->timer);
 177
 178         hash_idx = mesh_table_hash(dst, dev, mesh_paths);
 179         bucket = &mesh_paths->hash_buckets[hash_idx];
 180
 181         spin_lock(&mesh_paths->hashwlock[hash_idx]);
 182
 183         hlist_for_each_entry(node, n, bucket, list) {
 184                 mpath = node->mpath;
 185                 if (mpath->dev == dev && memcmp(dst, mpath->dst, ETH_ALEN)
 186                                 == 0) {
 187                         err = -EEXIST;
 188                         atomic_dec(&sdata->u.sta.mpaths);
 189                         kfree(new_node);
 190                         kfree(new_mpath);
 191                         goto endadd;
 192                 }
 193         }
 194
 195         hlist_add_head_rcu(&new_node->list, bucket);
 196         if (atomic_inc_return(&mesh_paths->entries) >=
 197                 mesh_paths->mean_chain_len * (mesh_paths->hash_mask + 1))
 198                 grow = 1;
 199
 200 endadd:
 201         spin_unlock(&mesh_paths->hashwlock[hash_idx]);
 202 endadd2:
 203         read_unlock(&pathtbl_resize_lock);
 204         if (!err && grow) {
 205                 struct mesh_table *oldtbl, *newtbl;
 206
 207                 write_lock(&pathtbl_resize_lock);
 208                 oldtbl = mesh_paths;
 209                 newtbl = mesh_table_grow(mesh_paths);
 210                 if (!newtbl) {
 211                         write_unlock(&pathtbl_resize_lock);
 212                         return -ENOMEM;
 213                 }
 214                 rcu_assign_pointer(mesh_paths, newtbl);
 215                 synchronize_rcu();
 216                 mesh_table_free(oldtbl, false);
 217                 write_unlock(&pathtbl_resize_lock);
 218         }
 219         return err;
 220 }
 221
 222
 223 /**
 224  * mesh_plink_broken - deactivates paths and sends perr when a link breaks
 225  *
 226  * @sta: broken peer link
 227  *
 228  * This function must be called from the rate control algorithm if enough
 229  * delivery errors suggest that a peer link is no longer usable.
 230  */
 231 void mesh_plink_broken(struct sta_info *sta)
 232 {
 233         struct mesh_path *mpath;
 234         struct mpath_node *node;
 235         struct hlist_node *p;
 236         struct net_device *dev = sta->sdata->dev;
 237         int i;
 238
 239         rcu_read_lock();
 240         for_each_mesh_entry(mesh_paths, p, node, i) {
 241                 mpath = node->mpath;
 242                 spin_lock_bh(&mpath->state_lock);
 243                 if (mpath->next_hop == sta &&
 244                     mpath->flags & MESH_PATH_ACTIVE &&
 245                     !(mpath->flags & MESH_PATH_FIXED)) {
 246                         mpath->flags &= ~MESH_PATH_ACTIVE;
 247                         ++mpath->dsn;
 248                         spin_unlock_bh(&mpath->state_lock);
 249                         mesh_path_error_tx(mpath->dst,
 250                                         cpu_to_le32(mpath->dsn),
 251                                         dev->broadcast, dev);
 252                 } else
 253                 spin_unlock_bh(&mpath->state_lock);
 254         }
 255         rcu_read_unlock();
 256 }
 257 EXPORT_SYMBOL(mesh_plink_broken);
 258
 259 /**
 260  * mesh_path_flush_by_nexthop - Deletes mesh paths if their next hop matches
 261  *
 262  * @sta - mesh peer to match
 263  *
 264  * RCU notes: this function is called when a mesh plink transitions from
 265  * PLINK_ESTAB to any other state, since PLINK_ESTAB state is the only one that
 266  * allows path creation. This will happen before the sta can be freed (because
 267  * sta_info_destroy() calls this) so any reader in a rcu read block will be
 268  * protected against the plink disappearing.
 269  */
 270 void mesh_path_flush_by_nexthop(struct sta_info *sta)
 271 {
 272         struct mesh_path *mpath;
 273         struct mpath_node *node;
 274         struct hlist_node *p;
 275         int i;
 276
 277         for_each_mesh_entry(mesh_paths, p, node, i) {
 278                 mpath = node->mpath;
 279                 if (mpath->next_hop == sta)
 280                         mesh_path_del(mpath->dst, mpath->dev);
 281         }
 282 }
 283
 284 void mesh_path_flush(struct net_device *dev)
 285 {
 286         struct mesh_path *mpath;
 287         struct mpath_node *node;
 288         struct hlist_node *p;
 289         int i;
 290
 291         for_each_mesh_entry(mesh_paths, p, node, i) {
 292                 mpath = node->mpath;
 293                 if (mpath->dev == dev)
 294                         mesh_path_del(mpath->dst, mpath->dev);
 295         }
 296 }
 297
 298 static void mesh_path_node_reclaim(struct rcu_head *rp)
 299 {
 300         struct mpath_node *node = container_of(rp, struct mpath_node, rcu);
 301         struct ieee80211_sub_if_data *sdata =
 302                 IEEE80211_DEV_TO_SUB_IF(node->mpath->dev);
 303
 304         del_timer_sync(&node->mpath->timer);
 305         atomic_dec(&sdata->u.sta.mpaths);
 306         kfree(node->mpath);
 307         kfree(node);
 308 }
 309
 310 /**
 311  * mesh_path_del - delete a mesh path from the table
 312  *
 313  * @addr: dst address (ETH_ALEN length)
 314  * @dev: local interface
 315  *
 316  * Returns: 0 if succesful
 317  */
 318 int mesh_path_del(u8 *addr, struct net_device *dev)
 319 {
 320         struct mesh_path *mpath;
 321         struct mpath_node *node;
 322         struct hlist_head *bucket;
 323         struct hlist_node *n;
 324         int hash_idx;
 325         int err = 0;
 326
 327         read_lock(&pathtbl_resize_lock);
 328         hash_idx = mesh_table_hash(addr, dev, mesh_paths);
 329         bucket = &mesh_paths->hash_buckets[hash_idx];
 330
 331         spin_lock(&mesh_paths->hashwlock[hash_idx]);
 332         hlist_for_each_entry(node, n, bucket, list) {
 333                 mpath = node->mpath;
 334                 if (mpath->dev == dev &&
 335                                 memcmp(addr, mpath->dst, ETH_ALEN) == 0) {
 336                         spin_lock_bh(&mpath->state_lock);
 337                         mpath->flags |= MESH_PATH_RESOLVING;
 338                         hlist_del_rcu(&node->list);
 339                         call_rcu(&node->rcu, mesh_path_node_reclaim);
 340                         atomic_dec(&mesh_paths->entries);
 341                         spin_unlock_bh(&mpath->state_lock);
 342                         goto enddel;
 343                 }
 344         }
 345
 346         err = -ENXIO;
 347 enddel:
 348         spin_unlock(&mesh_paths->hashwlock[hash_idx]);
 349         read_unlock(&pathtbl_resize_lock);
 350         return err;
 351 }
 352
 353 /**
 354  * mesh_path_tx_pending - sends pending frames in a mesh path queue
 355  *
 356  * @mpath: mesh path to activate
 357  *
 358  * Locking: the state_lock of the mpath structure must NOT be held when calling
 359  * this function.
 360  */
 361 void mesh_path_tx_pending(struct mesh_path *mpath)
 362 {
 363         struct sk_buff *skb;
 364
 365         while ((skb = skb_dequeue(&mpath->frame_queue)) &&
 366                         (mpath->flags & MESH_PATH_ACTIVE))
 367                 dev_queue_xmit(skb);
 368 }
 369
 370 /**
 371  * mesh_path_discard_frame - discard a frame whose path could not be resolved
 372  *
 373  * @skb: frame to discard
 374  * @dev: network device the frame was to be sent through
 375  *
 376  * If the frame was beign forwarded from another MP, a PERR frame will be sent
 377  * to the precursor.
 378  *
 379  * Locking: the function must me called within a rcu_read_lock region
 380  */
 381 void mesh_path_discard_frame(struct sk_buff *skb, struct net_device *dev)
 382 {
 383         struct ieee80211_sub_if_data *sdata = IEEE80211_DEV_TO_SUB_IF(dev);
 384         struct mesh_path *mpath;
 385         u32 dsn = 0;
 386
 387         if (skb->pkt_type == PACKET_OTHERHOST) {
 388                 struct ieee80211s_hdr *prev_meshhdr;
 389                 int mshhdrlen;
 390                 u8 *ra, *da;
 391
 392                 prev_meshhdr = ((struct ieee80211s_hdr *)skb->cb);
 393                 mshhdrlen = ieee80211_get_mesh_hdrlen(prev_meshhdr);
 394                 da = skb->data;
 395                 ra = MESH_PREQ(skb);
 396                 mpath = mesh_path_lookup(da, dev);
 397                 if (mpath)
 398                         dsn = ++mpath->dsn;
 399                 mesh_path_error_tx(skb->data, cpu_to_le32(dsn), ra, dev);
 400         }
 401
 402         kfree_skb(skb);
 403         sdata->u.sta.mshstats.dropped_frames_no_route++;
 404 }
 405
 406 /**
 407  * mesh_path_flush_pending - free the pending queue of a mesh path
 408  *
 409  * @mpath: mesh path whose queue has to be freed
 410  *
 411  * Locking: the function must me called withing a rcu_read_lock region
 412  */
 413 void mesh_path_flush_pending(struct mesh_path *mpath)
 414 {
 415         struct ieee80211_sub_if_data *sdata;
 416         struct sk_buff *skb;
 417
 418         sdata = IEEE80211_DEV_TO_SUB_IF(mpath->dev);
 419
 420         while ((skb = skb_dequeue(&mpath->frame_queue)) &&
 421                         (mpath->flags & MESH_PATH_ACTIVE))
 422                 mesh_path_discard_frame(skb, mpath->dev);
 423 }
 424
 425 /**
 426  * mesh_path_fix_nexthop - force a specific next hop for a mesh path
 427  *
 428  * @mpath: the mesh path to modify
 429  * @next_hop: the next hop to force
 430  *
 431  * Locking: this function must be called holding mpath->state_lock
 432  */
 433 void mesh_path_fix_nexthop(struct mesh_path *mpath, struct sta_info *next_hop)
 434 {
 435         spin_lock_bh(&mpath->state_lock);
 436         mesh_path_assign_nexthop(mpath, next_hop);
 437         mpath->dsn = 0xffff;
 438         mpath->metric = 0;
 439         mpath->hop_count = 0;
 440         mpath->exp_time = 0;
 441         mpath->flags |= MESH_PATH_FIXED;
 442         mesh_path_activate(mpath);
 443         spin_unlock_bh(&mpath->state_lock);
 444         mesh_path_tx_pending(mpath);
 445 }
 446
 447 static void mesh_path_node_free(struct hlist_node *p, bool free_leafs)
 448 {
 449         struct mesh_path *mpath;
 450         struct mpath_node *node = hlist_entry(p, struct mpath_node, list);
 451         mpath = node->mpath;
 452         hlist_del_rcu(p);
 453         synchronize_rcu();
 454         if (free_leafs)
 455                 kfree(mpath);
 456         kfree(node);
 457 }
 458
 459 static void mesh_path_node_copy(struct hlist_node *p, struct mesh_table *newtbl)
 460 {
 461         struct mesh_path *mpath;
 462         struct mpath_node *node, *new_node;
 463         u32 hash_idx;
 464
 465         node = hlist_entry(p, struct mpath_node, list);
 466         mpath = node->mpath;
 467         new_node = kmalloc(sizeof(struct mpath_node), GFP_KERNEL);
 468         new_node->mpath = mpath;
 469         hash_idx = mesh_table_hash(mpath->dst, mpath->dev, newtbl);
 470         hlist_add_head(&new_node->list,
 471                         &newtbl->hash_buckets[hash_idx]);
 472 }
 473
 474 int mesh_pathtbl_init(void)
 475 {
 476         mesh_paths = mesh_table_alloc(INIT_PATHS_SIZE_ORDER);
 477         mesh_paths->free_node = &mesh_path_node_free;
 478         mesh_paths->copy_node = &mesh_path_node_copy;
 479         mesh_paths->mean_chain_len = MEAN_CHAIN_LEN;
 480         if (!mesh_paths)
 481                 return -ENOMEM;
 482         return 0;
 483 }
 484
 485 void mesh_path_expire(struct net_device *dev)
 486 {
 487         struct mesh_path *mpath;
 488         struct mpath_node *node;
 489         struct hlist_node *p;
 490         int i;
 491
 492         read_lock(&pathtbl_resize_lock);
 493         for_each_mesh_entry(mesh_paths, p, node, i) {
 494                 if (node->mpath->dev != dev)
 495                         continue;
 496                 mpath = node->mpath;
 497                 spin_lock_bh(&mpath->state_lock);
 498                 if ((!(mpath->flags & MESH_PATH_RESOLVING)) &&
 499                     (!(mpath->flags & MESH_PATH_FIXED)) &&
 500                         time_after(jiffies,
 501                          mpath->exp_time + MESH_PATH_EXPIRE)) {
 502                         spin_unlock_bh(&mpath->state_lock);
 503                         mesh_path_del(mpath->dst, mpath->dev);
 504                 } else
 505                         spin_unlock_bh(&mpath->state_lock);
 506         }
 507         read_unlock(&pathtbl_resize_lock);
 508 }
 509
 510 void mesh_pathtbl_unregister(void)
 511 {
 512         mesh_table_free(mesh_paths, true);
 513 }