Root/
1 | /* |
2 | * INET An implementation of the TCP/IP protocol suite for the LINUX |
3 | * operating system. INET is implemented using the BSD Socket |
4 | * interface as the means of communication with the user level. |
5 | * |
6 | * Generic TIME_WAIT sockets functions |
7 | * |
8 | * From code orinally in TCP |
9 | */ |
10 | |
11 | #include <linux/kernel.h> |
12 | #include <linux/kmemcheck.h> |
13 | #include <linux/slab.h> |
14 | #include <net/inet_hashtables.h> |
15 | #include <net/inet_timewait_sock.h> |
16 | #include <net/ip.h> |
17 | |
18 | |
19 | /** |
20 | * inet_twsk_unhash - unhash a timewait socket from established hash |
21 | * @tw: timewait socket |
22 | * |
23 | * unhash a timewait socket from established hash, if hashed. |
24 | * ehash lock must be held by caller. |
25 | * Returns 1 if caller should call inet_twsk_put() after lock release. |
26 | */ |
27 | int inet_twsk_unhash(struct inet_timewait_sock *tw) |
28 | { |
29 | if (hlist_nulls_unhashed(&tw->tw_node)) |
30 | return 0; |
31 | |
32 | hlist_nulls_del_rcu(&tw->tw_node); |
33 | sk_nulls_node_init(&tw->tw_node); |
34 | /* |
35 | * We cannot call inet_twsk_put() ourself under lock, |
36 | * caller must call it for us. |
37 | */ |
38 | return 1; |
39 | } |
40 | |
41 | /** |
42 | * inet_twsk_bind_unhash - unhash a timewait socket from bind hash |
43 | * @tw: timewait socket |
44 | * @hashinfo: hashinfo pointer |
45 | * |
46 | * unhash a timewait socket from bind hash, if hashed. |
47 | * bind hash lock must be held by caller. |
48 | * Returns 1 if caller should call inet_twsk_put() after lock release. |
49 | */ |
50 | int inet_twsk_bind_unhash(struct inet_timewait_sock *tw, |
51 | struct inet_hashinfo *hashinfo) |
52 | { |
53 | struct inet_bind_bucket *tb = tw->tw_tb; |
54 | |
55 | if (!tb) |
56 | return 0; |
57 | |
58 | __hlist_del(&tw->tw_bind_node); |
59 | tw->tw_tb = NULL; |
60 | inet_bind_bucket_destroy(hashinfo->bind_bucket_cachep, tb); |
61 | /* |
62 | * We cannot call inet_twsk_put() ourself under lock, |
63 | * caller must call it for us. |
64 | */ |
65 | return 1; |
66 | } |
67 | |
68 | /* Must be called with locally disabled BHs. */ |
69 | static void __inet_twsk_kill(struct inet_timewait_sock *tw, |
70 | struct inet_hashinfo *hashinfo) |
71 | { |
72 | struct inet_bind_hashbucket *bhead; |
73 | int refcnt; |
74 | /* Unlink from established hashes. */ |
75 | spinlock_t *lock = inet_ehash_lockp(hashinfo, tw->tw_hash); |
76 | |
77 | spin_lock(lock); |
78 | refcnt = inet_twsk_unhash(tw); |
79 | spin_unlock(lock); |
80 | |
81 | /* Disassociate with bind bucket. */ |
82 | bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), tw->tw_num, |
83 | hashinfo->bhash_size)]; |
84 | |
85 | spin_lock(&bhead->lock); |
86 | refcnt += inet_twsk_bind_unhash(tw, hashinfo); |
87 | spin_unlock(&bhead->lock); |
88 | |
89 | #ifdef SOCK_REFCNT_DEBUG |
90 | if (atomic_read(&tw->tw_refcnt) != 1) { |
91 | printk(KERN_DEBUG "%s timewait_sock %p refcnt=%d\n", |
92 | tw->tw_prot->name, tw, atomic_read(&tw->tw_refcnt)); |
93 | } |
94 | #endif |
95 | while (refcnt) { |
96 | inet_twsk_put(tw); |
97 | refcnt--; |
98 | } |
99 | } |
100 | |
101 | static noinline void inet_twsk_free(struct inet_timewait_sock *tw) |
102 | { |
103 | struct module *owner = tw->tw_prot->owner; |
104 | twsk_destructor((struct sock *)tw); |
105 | #ifdef SOCK_REFCNT_DEBUG |
106 | pr_debug("%s timewait_sock %p released\n", tw->tw_prot->name, tw); |
107 | #endif |
108 | release_net(twsk_net(tw)); |
109 | kmem_cache_free(tw->tw_prot->twsk_prot->twsk_slab, tw); |
110 | module_put(owner); |
111 | } |
112 | |
113 | void inet_twsk_put(struct inet_timewait_sock *tw) |
114 | { |
115 | if (atomic_dec_and_test(&tw->tw_refcnt)) |
116 | inet_twsk_free(tw); |
117 | } |
118 | EXPORT_SYMBOL_GPL(inet_twsk_put); |
119 | |
120 | /* |
121 | * Enter the time wait state. This is called with locally disabled BH. |
122 | * Essentially we whip up a timewait bucket, copy the relevant info into it |
123 | * from the SK, and mess with hash chains and list linkage. |
124 | */ |
125 | void __inet_twsk_hashdance(struct inet_timewait_sock *tw, struct sock *sk, |
126 | struct inet_hashinfo *hashinfo) |
127 | { |
128 | const struct inet_sock *inet = inet_sk(sk); |
129 | const struct inet_connection_sock *icsk = inet_csk(sk); |
130 | struct inet_ehash_bucket *ehead = inet_ehash_bucket(hashinfo, sk->sk_hash); |
131 | spinlock_t *lock = inet_ehash_lockp(hashinfo, sk->sk_hash); |
132 | struct inet_bind_hashbucket *bhead; |
133 | /* Step 1: Put TW into bind hash. Original socket stays there too. |
134 | Note, that any socket with inet->num != 0 MUST be bound in |
135 | binding cache, even if it is closed. |
136 | */ |
137 | bhead = &hashinfo->bhash[inet_bhashfn(twsk_net(tw), inet->inet_num, |
138 | hashinfo->bhash_size)]; |
139 | spin_lock(&bhead->lock); |
140 | tw->tw_tb = icsk->icsk_bind_hash; |
141 | WARN_ON(!icsk->icsk_bind_hash); |
142 | inet_twsk_add_bind_node(tw, &tw->tw_tb->owners); |
143 | spin_unlock(&bhead->lock); |
144 | |
145 | spin_lock(lock); |
146 | |
147 | /* |
148 | * Step 2: Hash TW into TIMEWAIT chain. |
149 | * Should be done before removing sk from established chain |
150 | * because readers are lockless and search established first. |
151 | */ |
152 | inet_twsk_add_node_rcu(tw, &ehead->twchain); |
153 | |
154 | /* Step 3: Remove SK from established hash. */ |
155 | if (__sk_nulls_del_node_init_rcu(sk)) |
156 | sock_prot_inuse_add(sock_net(sk), sk->sk_prot, -1); |
157 | |
158 | /* |
159 | * Notes : |
160 | * - We initially set tw_refcnt to 0 in inet_twsk_alloc() |
161 | * - We add one reference for the bhash link |
162 | * - We add one reference for the ehash link |
163 | * - We want this refcnt update done before allowing other |
164 | * threads to find this tw in ehash chain. |
165 | */ |
166 | atomic_add(1 + 1 + 1, &tw->tw_refcnt); |
167 | |
168 | spin_unlock(lock); |
169 | } |
170 | EXPORT_SYMBOL_GPL(__inet_twsk_hashdance); |
171 | |
172 | struct inet_timewait_sock *inet_twsk_alloc(const struct sock *sk, const int state) |
173 | { |
174 | struct inet_timewait_sock *tw = |
175 | kmem_cache_alloc(sk->sk_prot_creator->twsk_prot->twsk_slab, |
176 | GFP_ATOMIC); |
177 | if (tw != NULL) { |
178 | const struct inet_sock *inet = inet_sk(sk); |
179 | |
180 | kmemcheck_annotate_bitfield(tw, flags); |
181 | |
182 | /* Give us an identity. */ |
183 | tw->tw_daddr = inet->inet_daddr; |
184 | tw->tw_rcv_saddr = inet->inet_rcv_saddr; |
185 | tw->tw_bound_dev_if = sk->sk_bound_dev_if; |
186 | tw->tw_num = inet->inet_num; |
187 | tw->tw_state = TCP_TIME_WAIT; |
188 | tw->tw_substate = state; |
189 | tw->tw_sport = inet->inet_sport; |
190 | tw->tw_dport = inet->inet_dport; |
191 | tw->tw_family = sk->sk_family; |
192 | tw->tw_reuse = sk->sk_reuse; |
193 | tw->tw_hash = sk->sk_hash; |
194 | tw->tw_ipv6only = 0; |
195 | tw->tw_transparent = inet->transparent; |
196 | tw->tw_prot = sk->sk_prot_creator; |
197 | twsk_net_set(tw, hold_net(sock_net(sk))); |
198 | /* |
199 | * Because we use RCU lookups, we should not set tw_refcnt |
200 | * to a non null value before everything is setup for this |
201 | * timewait socket. |
202 | */ |
203 | atomic_set(&tw->tw_refcnt, 0); |
204 | inet_twsk_dead_node_init(tw); |
205 | __module_get(tw->tw_prot->owner); |
206 | } |
207 | |
208 | return tw; |
209 | } |
210 | EXPORT_SYMBOL_GPL(inet_twsk_alloc); |
211 | |
212 | /* Returns non-zero if quota exceeded. */ |
213 | static int inet_twdr_do_twkill_work(struct inet_timewait_death_row *twdr, |
214 | const int slot) |
215 | { |
216 | struct inet_timewait_sock *tw; |
217 | struct hlist_node *node; |
218 | unsigned int killed; |
219 | int ret; |
220 | |
221 | /* NOTE: compare this to previous version where lock |
222 | * was released after detaching chain. It was racy, |
223 | * because tw buckets are scheduled in not serialized context |
224 | * in 2.3 (with netfilter), and with softnet it is common, because |
225 | * soft irqs are not sequenced. |
226 | */ |
227 | killed = 0; |
228 | ret = 0; |
229 | rescan: |
230 | inet_twsk_for_each_inmate(tw, node, &twdr->cells[slot]) { |
231 | __inet_twsk_del_dead_node(tw); |
232 | spin_unlock(&twdr->death_lock); |
233 | __inet_twsk_kill(tw, twdr->hashinfo); |
234 | #ifdef CONFIG_NET_NS |
235 | NET_INC_STATS_BH(twsk_net(tw), LINUX_MIB_TIMEWAITED); |
236 | #endif |
237 | inet_twsk_put(tw); |
238 | killed++; |
239 | spin_lock(&twdr->death_lock); |
240 | if (killed > INET_TWDR_TWKILL_QUOTA) { |
241 | ret = 1; |
242 | break; |
243 | } |
244 | |
245 | /* While we dropped twdr->death_lock, another cpu may have |
246 | * killed off the next TW bucket in the list, therefore |
247 | * do a fresh re-read of the hlist head node with the |
248 | * lock reacquired. We still use the hlist traversal |
249 | * macro in order to get the prefetches. |
250 | */ |
251 | goto rescan; |
252 | } |
253 | |
254 | twdr->tw_count -= killed; |
255 | #ifndef CONFIG_NET_NS |
256 | NET_ADD_STATS_BH(&init_net, LINUX_MIB_TIMEWAITED, killed); |
257 | #endif |
258 | return ret; |
259 | } |
260 | |
261 | void inet_twdr_hangman(unsigned long data) |
262 | { |
263 | struct inet_timewait_death_row *twdr; |
264 | int unsigned need_timer; |
265 | |
266 | twdr = (struct inet_timewait_death_row *)data; |
267 | spin_lock(&twdr->death_lock); |
268 | |
269 | if (twdr->tw_count == 0) |
270 | goto out; |
271 | |
272 | need_timer = 0; |
273 | if (inet_twdr_do_twkill_work(twdr, twdr->slot)) { |
274 | twdr->thread_slots |= (1 << twdr->slot); |
275 | schedule_work(&twdr->twkill_work); |
276 | need_timer = 1; |
277 | } else { |
278 | /* We purged the entire slot, anything left? */ |
279 | if (twdr->tw_count) |
280 | need_timer = 1; |
281 | twdr->slot = ((twdr->slot + 1) & (INET_TWDR_TWKILL_SLOTS - 1)); |
282 | } |
283 | if (need_timer) |
284 | mod_timer(&twdr->tw_timer, jiffies + twdr->period); |
285 | out: |
286 | spin_unlock(&twdr->death_lock); |
287 | } |
288 | EXPORT_SYMBOL_GPL(inet_twdr_hangman); |
289 | |
290 | void inet_twdr_twkill_work(struct work_struct *work) |
291 | { |
292 | struct inet_timewait_death_row *twdr = |
293 | container_of(work, struct inet_timewait_death_row, twkill_work); |
294 | int i; |
295 | |
296 | BUILD_BUG_ON((INET_TWDR_TWKILL_SLOTS - 1) > |
297 | (sizeof(twdr->thread_slots) * 8)); |
298 | |
299 | while (twdr->thread_slots) { |
300 | spin_lock_bh(&twdr->death_lock); |
301 | for (i = 0; i < INET_TWDR_TWKILL_SLOTS; i++) { |
302 | if (!(twdr->thread_slots & (1 << i))) |
303 | continue; |
304 | |
305 | while (inet_twdr_do_twkill_work(twdr, i) != 0) { |
306 | if (need_resched()) { |
307 | spin_unlock_bh(&twdr->death_lock); |
308 | schedule(); |
309 | spin_lock_bh(&twdr->death_lock); |
310 | } |
311 | } |
312 | |
313 | twdr->thread_slots &= ~(1 << i); |
314 | } |
315 | spin_unlock_bh(&twdr->death_lock); |
316 | } |
317 | } |
318 | EXPORT_SYMBOL_GPL(inet_twdr_twkill_work); |
319 | |
320 | /* These are always called from BH context. See callers in |
321 | * tcp_input.c to verify this. |
322 | */ |
323 | |
324 | /* This is for handling early-kills of TIME_WAIT sockets. */ |
325 | void inet_twsk_deschedule(struct inet_timewait_sock *tw, |
326 | struct inet_timewait_death_row *twdr) |
327 | { |
328 | spin_lock(&twdr->death_lock); |
329 | if (inet_twsk_del_dead_node(tw)) { |
330 | inet_twsk_put(tw); |
331 | if (--twdr->tw_count == 0) |
332 | del_timer(&twdr->tw_timer); |
333 | } |
334 | spin_unlock(&twdr->death_lock); |
335 | __inet_twsk_kill(tw, twdr->hashinfo); |
336 | } |
337 | EXPORT_SYMBOL(inet_twsk_deschedule); |
338 | |
339 | void inet_twsk_schedule(struct inet_timewait_sock *tw, |
340 | struct inet_timewait_death_row *twdr, |
341 | const int timeo, const int timewait_len) |
342 | { |
343 | struct hlist_head *list; |
344 | int slot; |
345 | |
346 | /* timeout := RTO * 3.5 |
347 | * |
348 | * 3.5 = 1+2+0.5 to wait for two retransmits. |
349 | * |
350 | * RATIONALE: if FIN arrived and we entered TIME-WAIT state, |
351 | * our ACK acking that FIN can be lost. If N subsequent retransmitted |
352 | * FINs (or previous seqments) are lost (probability of such event |
353 | * is p^(N+1), where p is probability to lose single packet and |
354 | * time to detect the loss is about RTO*(2^N - 1) with exponential |
355 | * backoff). Normal timewait length is calculated so, that we |
356 | * waited at least for one retransmitted FIN (maximal RTO is 120sec). |
357 | * [ BTW Linux. following BSD, violates this requirement waiting |
358 | * only for 60sec, we should wait at least for 240 secs. |
359 | * Well, 240 consumes too much of resources 8) |
360 | * ] |
361 | * This interval is not reduced to catch old duplicate and |
362 | * responces to our wandering segments living for two MSLs. |
363 | * However, if we use PAWS to detect |
364 | * old duplicates, we can reduce the interval to bounds required |
365 | * by RTO, rather than MSL. So, if peer understands PAWS, we |
366 | * kill tw bucket after 3.5*RTO (it is important that this number |
367 | * is greater than TS tick!) and detect old duplicates with help |
368 | * of PAWS. |
369 | */ |
370 | slot = (timeo + (1 << INET_TWDR_RECYCLE_TICK) - 1) >> INET_TWDR_RECYCLE_TICK; |
371 | |
372 | spin_lock(&twdr->death_lock); |
373 | |
374 | /* Unlink it, if it was scheduled */ |
375 | if (inet_twsk_del_dead_node(tw)) |
376 | twdr->tw_count--; |
377 | else |
378 | atomic_inc(&tw->tw_refcnt); |
379 | |
380 | if (slot >= INET_TWDR_RECYCLE_SLOTS) { |
381 | /* Schedule to slow timer */ |
382 | if (timeo >= timewait_len) { |
383 | slot = INET_TWDR_TWKILL_SLOTS - 1; |
384 | } else { |
385 | slot = DIV_ROUND_UP(timeo, twdr->period); |
386 | if (slot >= INET_TWDR_TWKILL_SLOTS) |
387 | slot = INET_TWDR_TWKILL_SLOTS - 1; |
388 | } |
389 | tw->tw_ttd = jiffies + timeo; |
390 | slot = (twdr->slot + slot) & (INET_TWDR_TWKILL_SLOTS - 1); |
391 | list = &twdr->cells[slot]; |
392 | } else { |
393 | tw->tw_ttd = jiffies + (slot << INET_TWDR_RECYCLE_TICK); |
394 | |
395 | if (twdr->twcal_hand < 0) { |
396 | twdr->twcal_hand = 0; |
397 | twdr->twcal_jiffie = jiffies; |
398 | twdr->twcal_timer.expires = twdr->twcal_jiffie + |
399 | (slot << INET_TWDR_RECYCLE_TICK); |
400 | add_timer(&twdr->twcal_timer); |
401 | } else { |
402 | if (time_after(twdr->twcal_timer.expires, |
403 | jiffies + (slot << INET_TWDR_RECYCLE_TICK))) |
404 | mod_timer(&twdr->twcal_timer, |
405 | jiffies + (slot << INET_TWDR_RECYCLE_TICK)); |
406 | slot = (twdr->twcal_hand + slot) & (INET_TWDR_RECYCLE_SLOTS - 1); |
407 | } |
408 | list = &twdr->twcal_row[slot]; |
409 | } |
410 | |
411 | hlist_add_head(&tw->tw_death_node, list); |
412 | |
413 | if (twdr->tw_count++ == 0) |
414 | mod_timer(&twdr->tw_timer, jiffies + twdr->period); |
415 | spin_unlock(&twdr->death_lock); |
416 | } |
417 | EXPORT_SYMBOL_GPL(inet_twsk_schedule); |
418 | |
419 | void inet_twdr_twcal_tick(unsigned long data) |
420 | { |
421 | struct inet_timewait_death_row *twdr; |
422 | int n, slot; |
423 | unsigned long j; |
424 | unsigned long now = jiffies; |
425 | int killed = 0; |
426 | int adv = 0; |
427 | |
428 | twdr = (struct inet_timewait_death_row *)data; |
429 | |
430 | spin_lock(&twdr->death_lock); |
431 | if (twdr->twcal_hand < 0) |
432 | goto out; |
433 | |
434 | slot = twdr->twcal_hand; |
435 | j = twdr->twcal_jiffie; |
436 | |
437 | for (n = 0; n < INET_TWDR_RECYCLE_SLOTS; n++) { |
438 | if (time_before_eq(j, now)) { |
439 | struct hlist_node *node, *safe; |
440 | struct inet_timewait_sock *tw; |
441 | |
442 | inet_twsk_for_each_inmate_safe(tw, node, safe, |
443 | &twdr->twcal_row[slot]) { |
444 | __inet_twsk_del_dead_node(tw); |
445 | __inet_twsk_kill(tw, twdr->hashinfo); |
446 | #ifdef CONFIG_NET_NS |
447 | NET_INC_STATS_BH(twsk_net(tw), LINUX_MIB_TIMEWAITKILLED); |
448 | #endif |
449 | inet_twsk_put(tw); |
450 | killed++; |
451 | } |
452 | } else { |
453 | if (!adv) { |
454 | adv = 1; |
455 | twdr->twcal_jiffie = j; |
456 | twdr->twcal_hand = slot; |
457 | } |
458 | |
459 | if (!hlist_empty(&twdr->twcal_row[slot])) { |
460 | mod_timer(&twdr->twcal_timer, j); |
461 | goto out; |
462 | } |
463 | } |
464 | j += 1 << INET_TWDR_RECYCLE_TICK; |
465 | slot = (slot + 1) & (INET_TWDR_RECYCLE_SLOTS - 1); |
466 | } |
467 | twdr->twcal_hand = -1; |
468 | |
469 | out: |
470 | if ((twdr->tw_count -= killed) == 0) |
471 | del_timer(&twdr->tw_timer); |
472 | #ifndef CONFIG_NET_NS |
473 | NET_ADD_STATS_BH(&init_net, LINUX_MIB_TIMEWAITKILLED, killed); |
474 | #endif |
475 | spin_unlock(&twdr->death_lock); |
476 | } |
477 | EXPORT_SYMBOL_GPL(inet_twdr_twcal_tick); |
478 | |
479 | void inet_twsk_purge(struct inet_hashinfo *hashinfo, |
480 | struct inet_timewait_death_row *twdr, int family) |
481 | { |
482 | struct inet_timewait_sock *tw; |
483 | struct sock *sk; |
484 | struct hlist_nulls_node *node; |
485 | unsigned int slot; |
486 | |
487 | for (slot = 0; slot <= hashinfo->ehash_mask; slot++) { |
488 | struct inet_ehash_bucket *head = &hashinfo->ehash[slot]; |
489 | restart_rcu: |
490 | rcu_read_lock(); |
491 | restart: |
492 | sk_nulls_for_each_rcu(sk, node, &head->twchain) { |
493 | tw = inet_twsk(sk); |
494 | if ((tw->tw_family != family) || |
495 | atomic_read(&twsk_net(tw)->count)) |
496 | continue; |
497 | |
498 | if (unlikely(!atomic_inc_not_zero(&tw->tw_refcnt))) |
499 | continue; |
500 | |
501 | if (unlikely((tw->tw_family != family) || |
502 | atomic_read(&twsk_net(tw)->count))) { |
503 | inet_twsk_put(tw); |
504 | goto restart; |
505 | } |
506 | |
507 | rcu_read_unlock(); |
508 | inet_twsk_deschedule(tw, twdr); |
509 | inet_twsk_put(tw); |
510 | goto restart_rcu; |
511 | } |
512 | /* If the nulls value we got at the end of this lookup is |
513 | * not the expected one, we must restart lookup. |
514 | * We probably met an item that was moved to another chain. |
515 | */ |
516 | if (get_nulls_value(node) != slot) |
517 | goto restart; |
518 | rcu_read_unlock(); |
519 | } |
520 | } |
521 | EXPORT_SYMBOL_GPL(inet_twsk_purge); |
522 |
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