1 /* 2 * INETPEER - A storage for permanent information about peers 3 * 4 * This source is covered by the GNU GPL, the same as all kernel sources. 5 * 6 * Authors: Andrey V. Savochkin <saw@msu.ru> 7 */ 8 9 #include <linux/module.h> 10 #include <linux/types.h> 11 #include <linux/slab.h> 12 #include <linux/interrupt.h> 13 #include <linux/spinlock.h> 14 #include <linux/random.h> 15 #include <linux/timer.h> 16 #include <linux/time.h> 17 #include <linux/kernel.h> 18 #include <linux/mm.h> 19 #include <linux/net.h> 20 #include <net/ip.h> 21 #include <net/inetpeer.h> 22 23 /* 24 * Theory of operations. 25 * We keep one entry for each peer IP address. The nodes contains long-living 26 * information about the peer which doesn't depend on routes. 27 * At this moment this information consists only of ID field for the next 28 * outgoing IP packet. This field is incremented with each packet as encoded 29 * in inet_getid() function (include/net/inetpeer.h). 30 * At the moment of writing this notes identifier of IP packets is generated 31 * to be unpredictable using this code only for packets subjected 32 * (actually or potentially) to defragmentation. I.e. DF packets less than 33 * PMTU in size uses a constant ID and do not use this code (see 34 * ip_select_ident() in include/net/ip.h). 35 * 36 * Route cache entries hold references to our nodes. 37 * New cache entries get references via lookup by destination IP address in 38 * the avl tree. The reference is grabbed only when it's needed i.e. only 39 * when we try to output IP packet which needs an unpredictable ID (see 40 * __ip_select_ident() in net/ipv4/route.c). 41 * Nodes are removed only when reference counter goes to 0. 42 * When it's happened the node may be removed when a sufficient amount of 43 * time has been passed since its last use. The less-recently-used entry can 44 * also be removed if the pool is overloaded i.e. if the total amount of 45 * entries is greater-or-equal than the threshold. 46 * 47 * Node pool is organised as an AVL tree. 48 * Such an implementation has been chosen not just for fun. It's a way to 49 * prevent easy and efficient DoS attacks by creating hash collisions. A huge 50 * amount of long living nodes in a single hash slot would significantly delay 51 * lookups performed with disabled BHs. 52 * 53 * Serialisation issues. 54 * 1. Nodes may appear in the tree only with the pool lock held. 55 * 2. Nodes may disappear from the tree only with the pool lock held 56 * AND reference count being 0. 57 * 3. Nodes appears and disappears from unused node list only under 58 * "inet_peer_unused_lock". 59 * 4. Global variable peer_total is modified under the pool lock. 60 * 5. struct inet_peer fields modification: 61 * avl_left, avl_right, avl_parent, avl_height: pool lock 62 * unused: unused node list lock 63 * refcnt: atomically against modifications on other CPU; 64 * usually under some other lock to prevent node disappearing 65 * dtime: unused node list lock 66 * daddr: unchangeable 67 * ip_id_count: atomic value (no lock needed) 68 */ 69 70 static struct kmem_cache *peer_cachep __read_mostly; 71 72 #define node_height(x) x->avl_height 73 74 #define peer_avl_empty ((struct inet_peer *)&peer_fake_node) 75 #define peer_avl_empty_rcu ((struct inet_peer __rcu __force *)&peer_fake_node) 76 static const struct inet_peer peer_fake_node = { 77 .avl_left = peer_avl_empty_rcu, 78 .avl_right = peer_avl_empty_rcu, 79 .avl_height = 0 80 }; 81 82 struct inet_peer_base { 83 struct inet_peer __rcu *root; 84 seqlock_t lock; 85 int total; 86 }; 87 88 static struct inet_peer_base v4_peers = { 89 .root = peer_avl_empty_rcu, 90 .lock = __SEQLOCK_UNLOCKED(v4_peers.lock), 91 .total = 0, 92 }; 93 94 static struct inet_peer_base v6_peers = { 95 .root = peer_avl_empty_rcu, 96 .lock = __SEQLOCK_UNLOCKED(v6_peers.lock), 97 .total = 0, 98 }; 99 100 #define PEER_MAXDEPTH 40 /* sufficient for about 2^27 nodes */ 101 102 /* Exported for sysctl_net_ipv4. */ 103 int inet_peer_threshold __read_mostly = 65536 + 128; /* start to throw entries more 104 * aggressively at this stage */ 105 int inet_peer_minttl __read_mostly = 120 * HZ; /* TTL under high load: 120 sec */ 106 int inet_peer_maxttl __read_mostly = 10 * 60 * HZ; /* usual time to live: 10 min */ 107 int inet_peer_gc_mintime __read_mostly = 10 * HZ; 108 int inet_peer_gc_maxtime __read_mostly = 120 * HZ; 109 110 static struct { 111 struct list_head list; 112 spinlock_t lock; 113 } unused_peers = { 114 .list = LIST_HEAD_INIT(unused_peers.list), 115 .lock = __SPIN_LOCK_UNLOCKED(unused_peers.lock), 116 }; 117 118 static void peer_check_expire(unsigned long dummy); 119 static DEFINE_TIMER(peer_periodic_timer, peer_check_expire, 0, 0); 120 121 122 /* Called from ip_output.c:ip_init */ 123 void __init inet_initpeers(void) 124 { 125 struct sysinfo si; 126 127 /* Use the straight interface to information about memory. */ 128 si_meminfo(&si); 129 /* The values below were suggested by Alexey Kuznetsov 130 * <kuznet@ms2.inr.ac.ru>. I don't have any opinion about the values 131 * myself. --SAW 132 */ 133 if (si.totalram <= (32768*1024)/PAGE_SIZE) 134 inet_peer_threshold >>= 1; /* max pool size about 1MB on IA32 */ 135 if (si.totalram <= (16384*1024)/PAGE_SIZE) 136 inet_peer_threshold >>= 1; /* about 512KB */ 137 if (si.totalram <= (8192*1024)/PAGE_SIZE) 138 inet_peer_threshold >>= 2; /* about 128KB */ 139 140 peer_cachep = kmem_cache_create("inet_peer_cache", 141 sizeof(struct inet_peer), 142 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, 143 NULL); 144 145 /* All the timers, started at system startup tend 146 to synchronize. Perturb it a bit. 147 */ 148 peer_periodic_timer.expires = jiffies 149 + net_random() % inet_peer_gc_maxtime 150 + inet_peer_gc_maxtime; 151 add_timer(&peer_periodic_timer); 152 } 153 154 /* Called with or without local BH being disabled. */ 155 static void unlink_from_unused(struct inet_peer *p) 156 { 157 if (!list_empty(&p->unused)) { 158 spin_lock_bh(&unused_peers.lock); 159 list_del_init(&p->unused); 160 spin_unlock_bh(&unused_peers.lock); 161 } 162 } 163 164 static int addr_compare(const struct inetpeer_addr *a, 165 const struct inetpeer_addr *b) 166 { 167 int i, n = (a->family == AF_INET ? 1 : 4); 168 169 for (i = 0; i < n; i++) { 170 if (a->addr.a6[i] == b->addr.a6[i]) 171 continue; 172 if (a->addr.a6[i] < b->addr.a6[i]) 173 return -1; 174 return 1; 175 } 176 177 return 0; 178 } 179 180 #define rcu_deref_locked(X, BASE) \ 181 rcu_dereference_protected(X, lockdep_is_held(&(BASE)->lock.lock)) 182 183 /* 184 * Called with local BH disabled and the pool lock held. 185 */ 186 #define lookup(_daddr, _stack, _base) \ 187 ({ \ 188 struct inet_peer *u; \ 189 struct inet_peer __rcu **v; \ 190 \ 191 stackptr = _stack; \ 192 *stackptr++ = &_base->root; \ 193 for (u = rcu_deref_locked(_base->root, _base); \ 194 u != peer_avl_empty; ) { \ 195 int cmp = addr_compare(_daddr, &u->daddr); \ 196 if (cmp == 0) \ 197 break; \ 198 if (cmp == -1) \ 199 v = &u->avl_left; \ 200 else \ 201 v = &u->avl_right; \ 202 *stackptr++ = v; \ 203 u = rcu_deref_locked(*v, _base); \ 204 } \ 205 u; \ 206 }) 207 208 /* 209 * Called with rcu_read_lock() 210 * Because we hold no lock against a writer, its quite possible we fall 211 * in an endless loop. 212 * But every pointer we follow is guaranteed to be valid thanks to RCU. 213 * We exit from this function if number of links exceeds PEER_MAXDEPTH 214 */ 215 static struct inet_peer *lookup_rcu(const struct inetpeer_addr *daddr, 216 struct inet_peer_base *base) 217 { 218 struct inet_peer *u = rcu_dereference(base->root); 219 int count = 0; 220 221 while (u != peer_avl_empty) { 222 int cmp = addr_compare(daddr, &u->daddr); 223 if (cmp == 0) { 224 /* Before taking a reference, check if this entry was 225 * deleted, unlink_from_pool() sets refcnt=-1 to make 226 * distinction between an unused entry (refcnt=0) and 227 * a freed one. 228 */ 229 if (unlikely(!atomic_add_unless(&u->refcnt, 1, -1))) 230 u = NULL; 231 return u; 232 } 233 if (cmp == -1) 234 u = rcu_dereference(u->avl_left); 235 else 236 u = rcu_dereference(u->avl_right); 237 if (unlikely(++count == PEER_MAXDEPTH)) 238 break; 239 } 240 return NULL; 241 } 242 243 /* Called with local BH disabled and the pool lock held. */ 244 #define lookup_rightempty(start, base) \ 245 ({ \ 246 struct inet_peer *u; \ 247 struct inet_peer __rcu **v; \ 248 *stackptr++ = &start->avl_left; \ 249 v = &start->avl_left; \ 250 for (u = rcu_deref_locked(*v, base); \ 251 u->avl_right != peer_avl_empty_rcu; ) { \ 252 v = &u->avl_right; \ 253 *stackptr++ = v; \ 254 u = rcu_deref_locked(*v, base); \ 255 } \ 256 u; \ 257 }) 258 259 /* Called with local BH disabled and the pool lock held. 260 * Variable names are the proof of operation correctness. 261 * Look into mm/map_avl.c for more detail description of the ideas. 262 */ 263 static void peer_avl_rebalance(struct inet_peer __rcu **stack[], 264 struct inet_peer __rcu ***stackend, 265 struct inet_peer_base *base) 266 { 267 struct inet_peer __rcu **nodep; 268 struct inet_peer *node, *l, *r; 269 int lh, rh; 270 271 while (stackend > stack) { 272 nodep = *--stackend; 273 node = rcu_deref_locked(*nodep, base); 274 l = rcu_deref_locked(node->avl_left, base); 275 r = rcu_deref_locked(node->avl_right, base); 276 lh = node_height(l); 277 rh = node_height(r); 278 if (lh > rh + 1) { /* l: RH+2 */ 279 struct inet_peer *ll, *lr, *lrl, *lrr; 280 int lrh; 281 ll = rcu_deref_locked(l->avl_left, base); 282 lr = rcu_deref_locked(l->avl_right, base); 283 lrh = node_height(lr); 284 if (lrh <= node_height(ll)) { /* ll: RH+1 */ 285 RCU_INIT_POINTER(node->avl_left, lr); /* lr: RH or RH+1 */ 286 RCU_INIT_POINTER(node->avl_right, r); /* r: RH */ 287 node->avl_height = lrh + 1; /* RH+1 or RH+2 */ 288 RCU_INIT_POINTER(l->avl_left, ll); /* ll: RH+1 */ 289 RCU_INIT_POINTER(l->avl_right, node); /* node: RH+1 or RH+2 */ 290 l->avl_height = node->avl_height + 1; 291 RCU_INIT_POINTER(*nodep, l); 292 } else { /* ll: RH, lr: RH+1 */ 293 lrl = rcu_deref_locked(lr->avl_left, base);/* lrl: RH or RH-1 */ 294 lrr = rcu_deref_locked(lr->avl_right, base);/* lrr: RH or RH-1 */ 295 RCU_INIT_POINTER(node->avl_left, lrr); /* lrr: RH or RH-1 */ 296 RCU_INIT_POINTER(node->avl_right, r); /* r: RH */ 297 node->avl_height = rh + 1; /* node: RH+1 */ 298 RCU_INIT_POINTER(l->avl_left, ll); /* ll: RH */ 299 RCU_INIT_POINTER(l->avl_right, lrl); /* lrl: RH or RH-1 */ 300 l->avl_height = rh + 1; /* l: RH+1 */ 301 RCU_INIT_POINTER(lr->avl_left, l); /* l: RH+1 */ 302 RCU_INIT_POINTER(lr->avl_right, node); /* node: RH+1 */ 303 lr->avl_height = rh + 2; 304 RCU_INIT_POINTER(*nodep, lr); 305 } 306 } else if (rh > lh + 1) { /* r: LH+2 */ 307 struct inet_peer *rr, *rl, *rlr, *rll; 308 int rlh; 309 rr = rcu_deref_locked(r->avl_right, base); 310 rl = rcu_deref_locked(r->avl_left, base); 311 rlh = node_height(rl); 312 if (rlh <= node_height(rr)) { /* rr: LH+1 */ 313 RCU_INIT_POINTER(node->avl_right, rl); /* rl: LH or LH+1 */ 314 RCU_INIT_POINTER(node->avl_left, l); /* l: LH */ 315 node->avl_height = rlh + 1; /* LH+1 or LH+2 */ 316 RCU_INIT_POINTER(r->avl_right, rr); /* rr: LH+1 */ 317 RCU_INIT_POINTER(r->avl_left, node); /* node: LH+1 or LH+2 */ 318 r->avl_height = node->avl_height + 1; 319 RCU_INIT_POINTER(*nodep, r); 320 } else { /* rr: RH, rl: RH+1 */ 321 rlr = rcu_deref_locked(rl->avl_right, base);/* rlr: LH or LH-1 */ 322 rll = rcu_deref_locked(rl->avl_left, base);/* rll: LH or LH-1 */ 323 RCU_INIT_POINTER(node->avl_right, rll); /* rll: LH or LH-1 */ 324 RCU_INIT_POINTER(node->avl_left, l); /* l: LH */ 325 node->avl_height = lh + 1; /* node: LH+1 */ 326 RCU_INIT_POINTER(r->avl_right, rr); /* rr: LH */ 327 RCU_INIT_POINTER(r->avl_left, rlr); /* rlr: LH or LH-1 */ 328 r->avl_height = lh + 1; /* r: LH+1 */ 329 RCU_INIT_POINTER(rl->avl_right, r); /* r: LH+1 */ 330 RCU_INIT_POINTER(rl->avl_left, node); /* node: LH+1 */ 331 rl->avl_height = lh + 2; 332 RCU_INIT_POINTER(*nodep, rl); 333 } 334 } else { 335 node->avl_height = (lh > rh ? lh : rh) + 1; 336 } 337 } 338 } 339 340 /* Called with local BH disabled and the pool lock held. */ 341 #define link_to_pool(n, base) \ 342 do { \ 343 n->avl_height = 1; \ 344 n->avl_left = peer_avl_empty_rcu; \ 345 n->avl_right = peer_avl_empty_rcu; \ 346 /* lockless readers can catch us now */ \ 347 rcu_assign_pointer(**--stackptr, n); \ 348 peer_avl_rebalance(stack, stackptr, base); \ 349 } while (0) 350 351 static void inetpeer_free_rcu(struct rcu_head *head) 352 { 353 kmem_cache_free(peer_cachep, container_of(head, struct inet_peer, rcu)); 354 } 355 356 /* May be called with local BH enabled. */ 357 static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base) 358 { 359 int do_free; 360 361 do_free = 0; 362 363 write_seqlock_bh(&base->lock); 364 /* Check the reference counter. It was artificially incremented by 1 365 * in cleanup() function to prevent sudden disappearing. If we can 366 * atomically (because of lockless readers) take this last reference, 367 * it's safe to remove the node and free it later. 368 * We use refcnt=-1 to alert lockless readers this entry is deleted. 369 */ 370 if (atomic_cmpxchg(&p->refcnt, 1, -1) == 1) { 371 struct inet_peer __rcu **stack[PEER_MAXDEPTH]; 372 struct inet_peer __rcu ***stackptr, ***delp; 373 if (lookup(&p->daddr, stack, base) != p) 374 BUG(); 375 delp = stackptr - 1; /* *delp[0] == p */ 376 if (p->avl_left == peer_avl_empty_rcu) { 377 *delp[0] = p->avl_right; 378 --stackptr; 379 } else { 380 /* look for a node to insert instead of p */ 381 struct inet_peer *t; 382 t = lookup_rightempty(p, base); 383 BUG_ON(rcu_deref_locked(*stackptr[-1], base) != t); 384 **--stackptr = t->avl_left; 385 /* t is removed, t->daddr > x->daddr for any 386 * x in p->avl_left subtree. 387 * Put t in the old place of p. */ 388 RCU_INIT_POINTER(*delp[0], t); 389 t->avl_left = p->avl_left; 390 t->avl_right = p->avl_right; 391 t->avl_height = p->avl_height; 392 BUG_ON(delp[1] != &p->avl_left); 393 delp[1] = &t->avl_left; /* was &p->avl_left */ 394 } 395 peer_avl_rebalance(stack, stackptr, base); 396 base->total--; 397 do_free = 1; 398 } 399 write_sequnlock_bh(&base->lock); 400 401 if (do_free) 402 call_rcu(&p->rcu, inetpeer_free_rcu); 403 else 404 /* The node is used again. Decrease the reference counter 405 * back. The loop "cleanup -> unlink_from_unused 406 * -> unlink_from_pool -> putpeer -> link_to_unused 407 * -> cleanup (for the same node)" 408 * doesn't really exist because the entry will have a 409 * recent deletion time and will not be cleaned again soon. 410 */ 411 inet_putpeer(p); 412 } 413 414 static struct inet_peer_base *family_to_base(int family) 415 { 416 return (family == AF_INET ? &v4_peers : &v6_peers); 417 } 418 419 static struct inet_peer_base *peer_to_base(struct inet_peer *p) 420 { 421 return family_to_base(p->daddr.family); 422 } 423 424 /* May be called with local BH enabled. */ 425 static int cleanup_once(unsigned long ttl) 426 { 427 struct inet_peer *p = NULL; 428 429 /* Remove the first entry from the list of unused nodes. */ 430 spin_lock_bh(&unused_peers.lock); 431 if (!list_empty(&unused_peers.list)) { 432 __u32 delta; 433 434 p = list_first_entry(&unused_peers.list, struct inet_peer, unused); 435 delta = (__u32)jiffies - p->dtime; 436 437 if (delta < ttl) { 438 /* Do not prune fresh entries. */ 439 spin_unlock_bh(&unused_peers.lock); 440 return -1; 441 } 442 443 list_del_init(&p->unused); 444 445 /* Grab an extra reference to prevent node disappearing 446 * before unlink_from_pool() call. */ 447 atomic_inc(&p->refcnt); 448 } 449 spin_unlock_bh(&unused_peers.lock); 450 451 if (p == NULL) 452 /* It means that the total number of USED entries has 453 * grown over inet_peer_threshold. It shouldn't really 454 * happen because of entry limits in route cache. */ 455 return -1; 456 457 unlink_from_pool(p, peer_to_base(p)); 458 return 0; 459 } 460 461 /* Called with or without local BH being disabled. */ 462 struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create) 463 { 464 struct inet_peer __rcu **stack[PEER_MAXDEPTH], ***stackptr; 465 struct inet_peer_base *base = family_to_base(daddr->family); 466 struct inet_peer *p; 467 unsigned int sequence; 468 int invalidated; 469 470 /* Look up for the address quickly, lockless. 471 * Because of a concurrent writer, we might not find an existing entry. 472 */ 473 rcu_read_lock(); 474 sequence = read_seqbegin(&base->lock); 475 p = lookup_rcu(daddr, base); 476 invalidated = read_seqretry(&base->lock, sequence); 477 rcu_read_unlock(); 478 479 if (p) { 480 /* The existing node has been found. 481 * Remove the entry from unused list if it was there. 482 */ 483 unlink_from_unused(p); 484 return p; 485 } 486 487 /* If no writer did a change during our lookup, we can return early. */ 488 if (!create && !invalidated) 489 return NULL; 490 491 /* retry an exact lookup, taking the lock before. 492 * At least, nodes should be hot in our cache. 493 */ 494 write_seqlock_bh(&base->lock); 495 p = lookup(daddr, stack, base); 496 if (p != peer_avl_empty) { 497 atomic_inc(&p->refcnt); 498 write_sequnlock_bh(&base->lock); 499 /* Remove the entry from unused list if it was there. */ 500 unlink_from_unused(p); 501 return p; 502 } 503 p = create ? kmem_cache_alloc(peer_cachep, GFP_ATOMIC) : NULL; 504 if (p) { 505 p->daddr = *daddr; 506 atomic_set(&p->refcnt, 1); 507 atomic_set(&p->rid, 0); 508 atomic_set(&p->ip_id_count, secure_ip_id(daddr->addr.a4)); 509 p->tcp_ts_stamp = 0; 510 p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW; 511 p->rate_tokens = 0; 512 p->rate_last = 0; 513 p->pmtu_expires = 0; 514 p->pmtu_orig = 0; 515 memset(&p->redirect_learned, 0, sizeof(p->redirect_learned)); 516 INIT_LIST_HEAD(&p->unused); 517 518 519 /* Link the node. */ 520 link_to_pool(p, base); 521 base->total++; 522 } 523 write_sequnlock_bh(&base->lock); 524 525 if (base->total >= inet_peer_threshold) 526 /* Remove one less-recently-used entry. */ 527 cleanup_once(0); 528 529 return p; 530 } 531 532 static int compute_total(void) 533 { 534 return v4_peers.total + v6_peers.total; 535 } 536 EXPORT_SYMBOL_GPL(inet_getpeer); 537 538 /* Called with local BH disabled. */ 539 static void peer_check_expire(unsigned long dummy) 540 { 541 unsigned long now = jiffies; 542 int ttl, total; 543 544 total = compute_total(); 545 if (total >= inet_peer_threshold) 546 ttl = inet_peer_minttl; 547 else 548 ttl = inet_peer_maxttl 549 - (inet_peer_maxttl - inet_peer_minttl) / HZ * 550 total / inet_peer_threshold * HZ; 551 while (!cleanup_once(ttl)) { 552 if (jiffies != now) 553 break; 554 } 555 556 /* Trigger the timer after inet_peer_gc_mintime .. inet_peer_gc_maxtime 557 * interval depending on the total number of entries (more entries, 558 * less interval). */ 559 total = compute_total(); 560 if (total >= inet_peer_threshold) 561 peer_periodic_timer.expires = jiffies + inet_peer_gc_mintime; 562 else 563 peer_periodic_timer.expires = jiffies 564 + inet_peer_gc_maxtime 565 - (inet_peer_gc_maxtime - inet_peer_gc_mintime) / HZ * 566 total / inet_peer_threshold * HZ; 567 add_timer(&peer_periodic_timer); 568 } 569 570 void inet_putpeer(struct inet_peer *p) 571 { 572 local_bh_disable(); 573 574 if (atomic_dec_and_lock(&p->refcnt, &unused_peers.lock)) { 575 list_add_tail(&p->unused, &unused_peers.list); 576 p->dtime = (__u32)jiffies; 577 spin_unlock(&unused_peers.lock); 578 } 579 580 local_bh_enable(); 581 } 582 EXPORT_SYMBOL_GPL(inet_putpeer); 583 584 /* 585 * Check transmit rate limitation for given message. 586 * The rate information is held in the inet_peer entries now. 587 * This function is generic and could be used for other purposes 588 * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov. 589 * 590 * Note that the same inet_peer fields are modified by functions in 591 * route.c too, but these work for packet destinations while xrlim_allow 592 * works for icmp destinations. This means the rate limiting information 593 * for one "ip object" is shared - and these ICMPs are twice limited: 594 * by source and by destination. 595 * 596 * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate 597 * SHOULD allow setting of rate limits 598 * 599 * Shared between ICMPv4 and ICMPv6. 600 */ 601 #define XRLIM_BURST_FACTOR 6 602 bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout) 603 { 604 unsigned long now, token; 605 bool rc = false; 606 607 if (!peer) 608 return true; 609 610 token = peer->rate_tokens; 611 now = jiffies; 612 token += now - peer->rate_last; 613 peer->rate_last = now; 614 if (token > XRLIM_BURST_FACTOR * timeout) 615 token = XRLIM_BURST_FACTOR * timeout; 616 if (token >= timeout) { 617 token -= timeout; 618 rc = true; 619 } 620 peer->rate_tokens = token; 621 return rc; 622 } 623 EXPORT_SYMBOL(inet_peer_xrlim_allow); 624