Commit | Line | Data |
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1da177e4 LT |
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 | * | |
1da177e4 LT |
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> | |
1da177e4 LT |
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> | |
20380731 | 20 | #include <net/ip.h> |
1da177e4 LT |
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. | |
aa1039e7 ED |
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 | |
1da177e4 | 56 | * AND reference count being 0. |
4b9d9be8 ED |
57 | * 3. Global variable peer_total is modified under the pool lock. |
58 | * 4. struct inet_peer fields modification: | |
1da177e4 | 59 | * avl_left, avl_right, avl_parent, avl_height: pool lock |
1da177e4 LT |
60 | * refcnt: atomically against modifications on other CPU; |
61 | * usually under some other lock to prevent node disappearing | |
582a72da | 62 | * daddr: unchangeable |
317fe0e6 | 63 | * ip_id_count: atomic value (no lock needed) |
1da177e4 LT |
64 | */ |
65 | ||
e18b890b | 66 | static struct kmem_cache *peer_cachep __read_mostly; |
1da177e4 LT |
67 | |
68 | #define node_height(x) x->avl_height | |
d6cc1d64 ED |
69 | |
70 | #define peer_avl_empty ((struct inet_peer *)&peer_fake_node) | |
b914c4ea | 71 | #define peer_avl_empty_rcu ((struct inet_peer __rcu __force *)&peer_fake_node) |
d6cc1d64 | 72 | static const struct inet_peer peer_fake_node = { |
b914c4ea ED |
73 | .avl_left = peer_avl_empty_rcu, |
74 | .avl_right = peer_avl_empty_rcu, | |
1da177e4 LT |
75 | .avl_height = 0 |
76 | }; | |
d6cc1d64 | 77 | |
021e9299 | 78 | struct inet_peer_base { |
b914c4ea | 79 | struct inet_peer __rcu *root; |
65e8354e | 80 | seqlock_t lock; |
d6cc1d64 | 81 | int total; |
021e9299 DM |
82 | }; |
83 | ||
84 | static struct inet_peer_base v4_peers = { | |
b914c4ea | 85 | .root = peer_avl_empty_rcu, |
65e8354e | 86 | .lock = __SEQLOCK_UNLOCKED(v4_peers.lock), |
d6cc1d64 ED |
87 | .total = 0, |
88 | }; | |
021e9299 DM |
89 | |
90 | static struct inet_peer_base v6_peers = { | |
91 | .root = peer_avl_empty_rcu, | |
65e8354e | 92 | .lock = __SEQLOCK_UNLOCKED(v6_peers.lock), |
021e9299 DM |
93 | .total = 0, |
94 | }; | |
95 | ||
1da177e4 LT |
96 | #define PEER_MAXDEPTH 40 /* sufficient for about 2^27 nodes */ |
97 | ||
1da177e4 | 98 | /* Exported for sysctl_net_ipv4. */ |
243bbcaa | 99 | int inet_peer_threshold __read_mostly = 65536 + 128; /* start to throw entries more |
1da177e4 | 100 | * aggressively at this stage */ |
243bbcaa ED |
101 | int inet_peer_minttl __read_mostly = 120 * HZ; /* TTL under high load: 120 sec */ |
102 | int inet_peer_maxttl __read_mostly = 10 * 60 * HZ; /* usual time to live: 10 min */ | |
1da177e4 | 103 | |
1da177e4 LT |
104 | |
105 | /* Called from ip_output.c:ip_init */ | |
106 | void __init inet_initpeers(void) | |
107 | { | |
108 | struct sysinfo si; | |
109 | ||
110 | /* Use the straight interface to information about memory. */ | |
111 | si_meminfo(&si); | |
112 | /* The values below were suggested by Alexey Kuznetsov | |
113 | * <kuznet@ms2.inr.ac.ru>. I don't have any opinion about the values | |
114 | * myself. --SAW | |
115 | */ | |
116 | if (si.totalram <= (32768*1024)/PAGE_SIZE) | |
117 | inet_peer_threshold >>= 1; /* max pool size about 1MB on IA32 */ | |
118 | if (si.totalram <= (16384*1024)/PAGE_SIZE) | |
119 | inet_peer_threshold >>= 1; /* about 512KB */ | |
120 | if (si.totalram <= (8192*1024)/PAGE_SIZE) | |
121 | inet_peer_threshold >>= 2; /* about 128KB */ | |
122 | ||
123 | peer_cachep = kmem_cache_create("inet_peer_cache", | |
124 | sizeof(struct inet_peer), | |
317fe0e6 | 125 | 0, SLAB_HWCACHE_ALIGN | SLAB_PANIC, |
20c2df83 | 126 | NULL); |
1da177e4 | 127 | |
1da177e4 LT |
128 | } |
129 | ||
8790ca17 DM |
130 | static int addr_compare(const struct inetpeer_addr *a, |
131 | const struct inetpeer_addr *b) | |
02663045 DM |
132 | { |
133 | int i, n = (a->family == AF_INET ? 1 : 4); | |
134 | ||
135 | for (i = 0; i < n; i++) { | |
7a71ed89 | 136 | if (a->addr.a6[i] == b->addr.a6[i]) |
02663045 | 137 | continue; |
7a71ed89 | 138 | if (a->addr.a6[i] < b->addr.a6[i]) |
02663045 DM |
139 | return -1; |
140 | return 1; | |
141 | } | |
142 | ||
143 | return 0; | |
144 | } | |
145 | ||
65e8354e ED |
146 | #define rcu_deref_locked(X, BASE) \ |
147 | rcu_dereference_protected(X, lockdep_is_held(&(BASE)->lock.lock)) | |
148 | ||
243bbcaa ED |
149 | /* |
150 | * Called with local BH disabled and the pool lock held. | |
243bbcaa | 151 | */ |
98158f5a | 152 | #define lookup(_daddr, _stack, _base) \ |
1da177e4 | 153 | ({ \ |
b914c4ea ED |
154 | struct inet_peer *u; \ |
155 | struct inet_peer __rcu **v; \ | |
aa1039e7 ED |
156 | \ |
157 | stackptr = _stack; \ | |
98158f5a | 158 | *stackptr++ = &_base->root; \ |
65e8354e | 159 | for (u = rcu_deref_locked(_base->root, _base); \ |
b914c4ea | 160 | u != peer_avl_empty; ) { \ |
02663045 DM |
161 | int cmp = addr_compare(_daddr, &u->daddr); \ |
162 | if (cmp == 0) \ | |
1da177e4 | 163 | break; \ |
02663045 | 164 | if (cmp == -1) \ |
1da177e4 LT |
165 | v = &u->avl_left; \ |
166 | else \ | |
167 | v = &u->avl_right; \ | |
aa1039e7 | 168 | *stackptr++ = v; \ |
65e8354e | 169 | u = rcu_deref_locked(*v, _base); \ |
1da177e4 LT |
170 | } \ |
171 | u; \ | |
172 | }) | |
173 | ||
aa1039e7 | 174 | /* |
7b46ac4e | 175 | * Called with rcu_read_lock() |
aa1039e7 ED |
176 | * Because we hold no lock against a writer, its quite possible we fall |
177 | * in an endless loop. | |
178 | * But every pointer we follow is guaranteed to be valid thanks to RCU. | |
179 | * We exit from this function if number of links exceeds PEER_MAXDEPTH | |
180 | */ | |
7b46ac4e | 181 | static struct inet_peer *lookup_rcu(const struct inetpeer_addr *daddr, |
4b9d9be8 | 182 | struct inet_peer_base *base) |
aa1039e7 | 183 | { |
7b46ac4e | 184 | struct inet_peer *u = rcu_dereference(base->root); |
aa1039e7 ED |
185 | int count = 0; |
186 | ||
187 | while (u != peer_avl_empty) { | |
02663045 DM |
188 | int cmp = addr_compare(daddr, &u->daddr); |
189 | if (cmp == 0) { | |
5f2f8920 | 190 | /* Before taking a reference, check if this entry was |
4b9d9be8 | 191 | * deleted (refcnt=-1) |
5f2f8920 | 192 | */ |
4b9d9be8 | 193 | if (!atomic_add_unless(&u->refcnt, 1, -1)) |
aa1039e7 ED |
194 | u = NULL; |
195 | return u; | |
196 | } | |
02663045 | 197 | if (cmp == -1) |
7b46ac4e | 198 | u = rcu_dereference(u->avl_left); |
aa1039e7 | 199 | else |
7b46ac4e | 200 | u = rcu_dereference(u->avl_right); |
aa1039e7 ED |
201 | if (unlikely(++count == PEER_MAXDEPTH)) |
202 | break; | |
203 | } | |
204 | return NULL; | |
205 | } | |
206 | ||
207 | /* Called with local BH disabled and the pool lock held. */ | |
98158f5a | 208 | #define lookup_rightempty(start, base) \ |
1da177e4 | 209 | ({ \ |
b914c4ea ED |
210 | struct inet_peer *u; \ |
211 | struct inet_peer __rcu **v; \ | |
1da177e4 LT |
212 | *stackptr++ = &start->avl_left; \ |
213 | v = &start->avl_left; \ | |
65e8354e | 214 | for (u = rcu_deref_locked(*v, base); \ |
b914c4ea | 215 | u->avl_right != peer_avl_empty_rcu; ) { \ |
1da177e4 LT |
216 | v = &u->avl_right; \ |
217 | *stackptr++ = v; \ | |
65e8354e | 218 | u = rcu_deref_locked(*v, base); \ |
1da177e4 LT |
219 | } \ |
220 | u; \ | |
221 | }) | |
222 | ||
aa1039e7 | 223 | /* Called with local BH disabled and the pool lock held. |
1da177e4 | 224 | * Variable names are the proof of operation correctness. |
aa1039e7 ED |
225 | * Look into mm/map_avl.c for more detail description of the ideas. |
226 | */ | |
b914c4ea | 227 | static void peer_avl_rebalance(struct inet_peer __rcu **stack[], |
98158f5a DM |
228 | struct inet_peer __rcu ***stackend, |
229 | struct inet_peer_base *base) | |
1da177e4 | 230 | { |
b914c4ea ED |
231 | struct inet_peer __rcu **nodep; |
232 | struct inet_peer *node, *l, *r; | |
1da177e4 LT |
233 | int lh, rh; |
234 | ||
235 | while (stackend > stack) { | |
236 | nodep = *--stackend; | |
65e8354e ED |
237 | node = rcu_deref_locked(*nodep, base); |
238 | l = rcu_deref_locked(node->avl_left, base); | |
239 | r = rcu_deref_locked(node->avl_right, base); | |
1da177e4 LT |
240 | lh = node_height(l); |
241 | rh = node_height(r); | |
242 | if (lh > rh + 1) { /* l: RH+2 */ | |
243 | struct inet_peer *ll, *lr, *lrl, *lrr; | |
244 | int lrh; | |
65e8354e ED |
245 | ll = rcu_deref_locked(l->avl_left, base); |
246 | lr = rcu_deref_locked(l->avl_right, base); | |
1da177e4 LT |
247 | lrh = node_height(lr); |
248 | if (lrh <= node_height(ll)) { /* ll: RH+1 */ | |
b914c4ea ED |
249 | RCU_INIT_POINTER(node->avl_left, lr); /* lr: RH or RH+1 */ |
250 | RCU_INIT_POINTER(node->avl_right, r); /* r: RH */ | |
1da177e4 | 251 | node->avl_height = lrh + 1; /* RH+1 or RH+2 */ |
b914c4ea ED |
252 | RCU_INIT_POINTER(l->avl_left, ll); /* ll: RH+1 */ |
253 | RCU_INIT_POINTER(l->avl_right, node); /* node: RH+1 or RH+2 */ | |
1da177e4 | 254 | l->avl_height = node->avl_height + 1; |
b914c4ea | 255 | RCU_INIT_POINTER(*nodep, l); |
1da177e4 | 256 | } else { /* ll: RH, lr: RH+1 */ |
65e8354e ED |
257 | lrl = rcu_deref_locked(lr->avl_left, base);/* lrl: RH or RH-1 */ |
258 | lrr = rcu_deref_locked(lr->avl_right, base);/* lrr: RH or RH-1 */ | |
b914c4ea ED |
259 | RCU_INIT_POINTER(node->avl_left, lrr); /* lrr: RH or RH-1 */ |
260 | RCU_INIT_POINTER(node->avl_right, r); /* r: RH */ | |
1da177e4 | 261 | node->avl_height = rh + 1; /* node: RH+1 */ |
b914c4ea ED |
262 | RCU_INIT_POINTER(l->avl_left, ll); /* ll: RH */ |
263 | RCU_INIT_POINTER(l->avl_right, lrl); /* lrl: RH or RH-1 */ | |
1da177e4 | 264 | l->avl_height = rh + 1; /* l: RH+1 */ |
b914c4ea ED |
265 | RCU_INIT_POINTER(lr->avl_left, l); /* l: RH+1 */ |
266 | RCU_INIT_POINTER(lr->avl_right, node); /* node: RH+1 */ | |
1da177e4 | 267 | lr->avl_height = rh + 2; |
b914c4ea | 268 | RCU_INIT_POINTER(*nodep, lr); |
1da177e4 LT |
269 | } |
270 | } else if (rh > lh + 1) { /* r: LH+2 */ | |
271 | struct inet_peer *rr, *rl, *rlr, *rll; | |
272 | int rlh; | |
65e8354e ED |
273 | rr = rcu_deref_locked(r->avl_right, base); |
274 | rl = rcu_deref_locked(r->avl_left, base); | |
1da177e4 LT |
275 | rlh = node_height(rl); |
276 | if (rlh <= node_height(rr)) { /* rr: LH+1 */ | |
b914c4ea ED |
277 | RCU_INIT_POINTER(node->avl_right, rl); /* rl: LH or LH+1 */ |
278 | RCU_INIT_POINTER(node->avl_left, l); /* l: LH */ | |
1da177e4 | 279 | node->avl_height = rlh + 1; /* LH+1 or LH+2 */ |
b914c4ea ED |
280 | RCU_INIT_POINTER(r->avl_right, rr); /* rr: LH+1 */ |
281 | RCU_INIT_POINTER(r->avl_left, node); /* node: LH+1 or LH+2 */ | |
1da177e4 | 282 | r->avl_height = node->avl_height + 1; |
b914c4ea | 283 | RCU_INIT_POINTER(*nodep, r); |
1da177e4 | 284 | } else { /* rr: RH, rl: RH+1 */ |
65e8354e ED |
285 | rlr = rcu_deref_locked(rl->avl_right, base);/* rlr: LH or LH-1 */ |
286 | rll = rcu_deref_locked(rl->avl_left, base);/* rll: LH or LH-1 */ | |
b914c4ea ED |
287 | RCU_INIT_POINTER(node->avl_right, rll); /* rll: LH or LH-1 */ |
288 | RCU_INIT_POINTER(node->avl_left, l); /* l: LH */ | |
1da177e4 | 289 | node->avl_height = lh + 1; /* node: LH+1 */ |
b914c4ea ED |
290 | RCU_INIT_POINTER(r->avl_right, rr); /* rr: LH */ |
291 | RCU_INIT_POINTER(r->avl_left, rlr); /* rlr: LH or LH-1 */ | |
1da177e4 | 292 | r->avl_height = lh + 1; /* r: LH+1 */ |
b914c4ea ED |
293 | RCU_INIT_POINTER(rl->avl_right, r); /* r: LH+1 */ |
294 | RCU_INIT_POINTER(rl->avl_left, node); /* node: LH+1 */ | |
1da177e4 | 295 | rl->avl_height = lh + 2; |
b914c4ea | 296 | RCU_INIT_POINTER(*nodep, rl); |
1da177e4 LT |
297 | } |
298 | } else { | |
299 | node->avl_height = (lh > rh ? lh : rh) + 1; | |
300 | } | |
301 | } | |
302 | } | |
303 | ||
aa1039e7 | 304 | /* Called with local BH disabled and the pool lock held. */ |
98158f5a | 305 | #define link_to_pool(n, base) \ |
1da177e4 LT |
306 | do { \ |
307 | n->avl_height = 1; \ | |
b914c4ea ED |
308 | n->avl_left = peer_avl_empty_rcu; \ |
309 | n->avl_right = peer_avl_empty_rcu; \ | |
310 | /* lockless readers can catch us now */ \ | |
311 | rcu_assign_pointer(**--stackptr, n); \ | |
98158f5a | 312 | peer_avl_rebalance(stack, stackptr, base); \ |
d6cc1d64 | 313 | } while (0) |
1da177e4 | 314 | |
aa1039e7 ED |
315 | static void inetpeer_free_rcu(struct rcu_head *head) |
316 | { | |
317 | kmem_cache_free(peer_cachep, container_of(head, struct inet_peer, rcu)); | |
318 | } | |
319 | ||
66944e1c ED |
320 | static void unlink_from_pool(struct inet_peer *p, struct inet_peer_base *base, |
321 | struct inet_peer __rcu **stack[PEER_MAXDEPTH]) | |
1da177e4 | 322 | { |
4b9d9be8 ED |
323 | struct inet_peer __rcu ***stackptr, ***delp; |
324 | ||
325 | if (lookup(&p->daddr, stack, base) != p) | |
326 | BUG(); | |
327 | delp = stackptr - 1; /* *delp[0] == p */ | |
328 | if (p->avl_left == peer_avl_empty_rcu) { | |
329 | *delp[0] = p->avl_right; | |
330 | --stackptr; | |
331 | } else { | |
332 | /* look for a node to insert instead of p */ | |
333 | struct inet_peer *t; | |
334 | t = lookup_rightempty(p, base); | |
335 | BUG_ON(rcu_deref_locked(*stackptr[-1], base) != t); | |
336 | **--stackptr = t->avl_left; | |
337 | /* t is removed, t->daddr > x->daddr for any | |
338 | * x in p->avl_left subtree. | |
339 | * Put t in the old place of p. */ | |
340 | RCU_INIT_POINTER(*delp[0], t); | |
341 | t->avl_left = p->avl_left; | |
342 | t->avl_right = p->avl_right; | |
343 | t->avl_height = p->avl_height; | |
344 | BUG_ON(delp[1] != &p->avl_left); | |
345 | delp[1] = &t->avl_left; /* was &p->avl_left */ | |
1da177e4 | 346 | } |
4b9d9be8 ED |
347 | peer_avl_rebalance(stack, stackptr, base); |
348 | base->total--; | |
349 | call_rcu(&p->rcu, inetpeer_free_rcu); | |
1da177e4 LT |
350 | } |
351 | ||
021e9299 DM |
352 | static struct inet_peer_base *family_to_base(int family) |
353 | { | |
4b9d9be8 | 354 | return family == AF_INET ? &v4_peers : &v6_peers; |
021e9299 DM |
355 | } |
356 | ||
4b9d9be8 ED |
357 | /* perform garbage collect on all items stacked during a lookup */ |
358 | static int inet_peer_gc(struct inet_peer_base *base, | |
359 | struct inet_peer __rcu **stack[PEER_MAXDEPTH], | |
360 | struct inet_peer __rcu ***stackptr) | |
98158f5a | 361 | { |
4b9d9be8 ED |
362 | struct inet_peer *p, *gchead = NULL; |
363 | __u32 delta, ttl; | |
364 | int cnt = 0; | |
d71209de | 365 | |
4b9d9be8 ED |
366 | if (base->total >= inet_peer_threshold) |
367 | ttl = 0; /* be aggressive */ | |
368 | else | |
369 | ttl = inet_peer_maxttl | |
370 | - (inet_peer_maxttl - inet_peer_minttl) / HZ * | |
371 | base->total / inet_peer_threshold * HZ; | |
372 | stackptr--; /* last stack slot is peer_avl_empty */ | |
373 | while (stackptr > stack) { | |
374 | stackptr--; | |
375 | p = rcu_deref_locked(**stackptr, base); | |
6d1a3e04 ED |
376 | if (atomic_read(&p->refcnt) == 0) { |
377 | smp_rmb(); | |
378 | delta = (__u32)jiffies - p->dtime; | |
379 | if (delta >= ttl && | |
380 | atomic_cmpxchg(&p->refcnt, 0, -1) == 0) { | |
381 | p->gc_next = gchead; | |
382 | gchead = p; | |
383 | } | |
1da177e4 | 384 | } |
1da177e4 | 385 | } |
4b9d9be8 ED |
386 | while ((p = gchead) != NULL) { |
387 | gchead = p->gc_next; | |
388 | cnt++; | |
389 | unlink_from_pool(p, base, stack); | |
390 | } | |
391 | return cnt; | |
1da177e4 LT |
392 | } |
393 | ||
8790ca17 | 394 | struct inet_peer *inet_getpeer(struct inetpeer_addr *daddr, int create) |
1da177e4 | 395 | { |
b914c4ea | 396 | struct inet_peer __rcu **stack[PEER_MAXDEPTH], ***stackptr; |
3408404a | 397 | struct inet_peer_base *base = family_to_base(daddr->family); |
98158f5a | 398 | struct inet_peer *p; |
65e8354e | 399 | unsigned int sequence; |
4b9d9be8 | 400 | int invalidated, gccnt = 0; |
1da177e4 | 401 | |
4b9d9be8 | 402 | /* Attempt a lockless lookup first. |
aa1039e7 ED |
403 | * Because of a concurrent writer, we might not find an existing entry. |
404 | */ | |
7b46ac4e | 405 | rcu_read_lock(); |
65e8354e | 406 | sequence = read_seqbegin(&base->lock); |
4b9d9be8 | 407 | p = lookup_rcu(daddr, base); |
65e8354e | 408 | invalidated = read_seqretry(&base->lock, sequence); |
7b46ac4e | 409 | rcu_read_unlock(); |
aa1039e7 | 410 | |
4b9d9be8 | 411 | if (p) |
aa1039e7 | 412 | return p; |
1da177e4 | 413 | |
65e8354e ED |
414 | /* If no writer did a change during our lookup, we can return early. */ |
415 | if (!create && !invalidated) | |
416 | return NULL; | |
417 | ||
aa1039e7 ED |
418 | /* retry an exact lookup, taking the lock before. |
419 | * At least, nodes should be hot in our cache. | |
420 | */ | |
65e8354e | 421 | write_seqlock_bh(&base->lock); |
4b9d9be8 | 422 | relookup: |
02663045 | 423 | p = lookup(daddr, stack, base); |
1da177e4 | 424 | if (p != peer_avl_empty) { |
4b9d9be8 | 425 | atomic_inc(&p->refcnt); |
65e8354e | 426 | write_sequnlock_bh(&base->lock); |
4b9d9be8 ED |
427 | return p; |
428 | } | |
429 | if (!gccnt) { | |
430 | gccnt = inet_peer_gc(base, stack, stackptr); | |
431 | if (gccnt && create) | |
432 | goto relookup; | |
1da177e4 | 433 | } |
aa1039e7 ED |
434 | p = create ? kmem_cache_alloc(peer_cachep, GFP_ATOMIC) : NULL; |
435 | if (p) { | |
b534ecf1 | 436 | p->daddr = *daddr; |
aa1039e7 ED |
437 | atomic_set(&p->refcnt, 1); |
438 | atomic_set(&p->rid, 0); | |
7a71ed89 | 439 | atomic_set(&p->ip_id_count, secure_ip_id(daddr->addr.a4)); |
aa1039e7 | 440 | p->tcp_ts_stamp = 0; |
144001bd | 441 | p->metrics[RTAX_LOCK-1] = INETPEER_METRICS_NEW; |
92d86829 DM |
442 | p->rate_tokens = 0; |
443 | p->rate_last = 0; | |
ddd4aa42 | 444 | p->pmtu_expires = 0; |
46af3180 | 445 | p->pmtu_orig = 0; |
ddd4aa42 | 446 | memset(&p->redirect_learned, 0, sizeof(p->redirect_learned)); |
aa1039e7 ED |
447 | |
448 | ||
449 | /* Link the node. */ | |
98158f5a DM |
450 | link_to_pool(p, base); |
451 | base->total++; | |
aa1039e7 | 452 | } |
65e8354e | 453 | write_sequnlock_bh(&base->lock); |
1da177e4 | 454 | |
1da177e4 LT |
455 | return p; |
456 | } | |
b3419363 | 457 | EXPORT_SYMBOL_GPL(inet_getpeer); |
98158f5a | 458 | |
4663afe2 ED |
459 | void inet_putpeer(struct inet_peer *p) |
460 | { | |
4b9d9be8 | 461 | p->dtime = (__u32)jiffies; |
6d1a3e04 | 462 | smp_mb__before_atomic_dec(); |
4b9d9be8 | 463 | atomic_dec(&p->refcnt); |
4663afe2 | 464 | } |
b3419363 | 465 | EXPORT_SYMBOL_GPL(inet_putpeer); |
92d86829 DM |
466 | |
467 | /* | |
468 | * Check transmit rate limitation for given message. | |
469 | * The rate information is held in the inet_peer entries now. | |
470 | * This function is generic and could be used for other purposes | |
471 | * too. It uses a Token bucket filter as suggested by Alexey Kuznetsov. | |
472 | * | |
473 | * Note that the same inet_peer fields are modified by functions in | |
474 | * route.c too, but these work for packet destinations while xrlim_allow | |
475 | * works for icmp destinations. This means the rate limiting information | |
476 | * for one "ip object" is shared - and these ICMPs are twice limited: | |
477 | * by source and by destination. | |
478 | * | |
479 | * RFC 1812: 4.3.2.8 SHOULD be able to limit error message rate | |
480 | * SHOULD allow setting of rate limits | |
481 | * | |
482 | * Shared between ICMPv4 and ICMPv6. | |
483 | */ | |
484 | #define XRLIM_BURST_FACTOR 6 | |
485 | bool inet_peer_xrlim_allow(struct inet_peer *peer, int timeout) | |
486 | { | |
487 | unsigned long now, token; | |
488 | bool rc = false; | |
489 | ||
490 | if (!peer) | |
491 | return true; | |
492 | ||
493 | token = peer->rate_tokens; | |
494 | now = jiffies; | |
495 | token += now - peer->rate_last; | |
496 | peer->rate_last = now; | |
497 | if (token > XRLIM_BURST_FACTOR * timeout) | |
498 | token = XRLIM_BURST_FACTOR * timeout; | |
499 | if (token >= timeout) { | |
500 | token -= timeout; | |
501 | rc = true; | |
502 | } | |
503 | peer->rate_tokens = token; | |
504 | return rc; | |
505 | } | |
506 | EXPORT_SYMBOL(inet_peer_xrlim_allow); |