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Merge branch 'component' of git://ftp.arm.linux.org.uk/~rmk/linux-arm
[linux/fpc-iii.git] / net / ipv4 / inet_fragment.c
blob3a88b0c73797231e1468de8297045c8ad725ccfa
1 /*
2 * inet fragments management
3 *
4 * This program is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU General Public License
6 * as published by the Free Software Foundation; either version
7 * 2 of the License, or (at your option) any later version.
8 *
9 * Authors: Pavel Emelyanov <xemul@openvz.org>
10 * Started as consolidation of ipv4/ip_fragment.c,
11 * ipv6/reassembly. and ipv6 nf conntrack reassembly
12 */
13
14 #include <linux/list.h>
15 #include <linux/spinlock.h>
16 #include <linux/module.h>
17 #include <linux/timer.h>
18 #include <linux/mm.h>
19 #include <linux/random.h>
20 #include <linux/skbuff.h>
21 #include <linux/rtnetlink.h>
22 #include <linux/slab.h>
23
24 #include <net/sock.h>
25 #include <net/inet_frag.h>
26 #include <net/inet_ecn.h>
27
28 #define INETFRAGS_EVICT_BUCKETS 128
29 #define INETFRAGS_EVICT_MAX 512
30
31 /* don't rebuild inetfrag table with new secret more often than this */
32 #define INETFRAGS_MIN_REBUILD_INTERVAL (5 * HZ)
33
34 /* Given the OR values of all fragments, apply RFC 3168 5.3 requirements
35 * Value : 0xff if frame should be dropped.
36 * 0 or INET_ECN_CE value, to be ORed in to final iph->tos field
37 */
38 const u8 ip_frag_ecn_table[16] = {
39 /* at least one fragment had CE, and others ECT_0 or ECT_1 */
40 [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = INET_ECN_CE,
41 [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = INET_ECN_CE,
42 [IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = INET_ECN_CE,
43
44 /* invalid combinations : drop frame */
45 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE] = 0xff,
46 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0] = 0xff,
47 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_1] = 0xff,
48 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
49 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0] = 0xff,
50 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_1] = 0xff,
51 [IPFRAG_ECN_NOT_ECT | IPFRAG_ECN_CE | IPFRAG_ECN_ECT_0 | IPFRAG_ECN_ECT_1] = 0xff,
52 };
53 EXPORT_SYMBOL(ip_frag_ecn_table);
54
55 static unsigned int
56 inet_frag_hashfn(const struct inet_frags *f, const struct inet_frag_queue *q)
57 {
58 return f->hashfn(q) & (INETFRAGS_HASHSZ - 1);
59 }
60
61 static bool inet_frag_may_rebuild(struct inet_frags *f)
62 {
63 return time_after(jiffies,
64 f->last_rebuild_jiffies + INETFRAGS_MIN_REBUILD_INTERVAL);
65 }
66
67 static void inet_frag_secret_rebuild(struct inet_frags *f)
68 {
69 int i;
70
71 write_seqlock_bh(&f->rnd_seqlock);
72
73 if (!inet_frag_may_rebuild(f))
74 goto out;
75
76 get_random_bytes(&f->rnd, sizeof(u32));
77
78 for (i = 0; i < INETFRAGS_HASHSZ; i++) {
79 struct inet_frag_bucket *hb;
80 struct inet_frag_queue *q;
81 struct hlist_node *n;
82
83 hb = &f->hash[i];
84 spin_lock(&hb->chain_lock);
85
86 hlist_for_each_entry_safe(q, n, &hb->chain, list) {
87 unsigned int hval = inet_frag_hashfn(f, q);
88
89 if (hval != i) {
90 struct inet_frag_bucket *hb_dest;
91
92 hlist_del(&q->list);
93
94 /* Relink to new hash chain. */
95 hb_dest = &f->hash[hval];
96
97 /* This is the only place where we take
98 * another chain_lock while already holding
99 * one. As this will not run concurrently,
100 * we cannot deadlock on hb_dest lock below, if its
101 * already locked it will be released soon since
102 * other caller cannot be waiting for hb lock
103 * that we've taken above.
104 */
105 spin_lock_nested(&hb_dest->chain_lock,
106 SINGLE_DEPTH_NESTING);
107 hlist_add_head(&q->list, &hb_dest->chain);
108 spin_unlock(&hb_dest->chain_lock);
109 }
110 }
111 spin_unlock(&hb->chain_lock);
112 }
113
114 f->rebuild = false;
115 f->last_rebuild_jiffies = jiffies;
116 out:
117 write_sequnlock_bh(&f->rnd_seqlock);
118 }
119
120 static bool inet_fragq_should_evict(const struct inet_frag_queue *q)
121 {
122 return q->net->low_thresh == 0 ||
123 frag_mem_limit(q->net) >= q->net->low_thresh;
124 }
125
126 static unsigned int
127 inet_evict_bucket(struct inet_frags *f, struct inet_frag_bucket *hb)
128 {
129 struct inet_frag_queue *fq;
130 struct hlist_node *n;
131 unsigned int evicted = 0;
132 HLIST_HEAD(expired);
133
134 spin_lock(&hb->chain_lock);
135
136 hlist_for_each_entry_safe(fq, n, &hb->chain, list) {
137 if (!inet_fragq_should_evict(fq))
138 continue;
139
140 if (!del_timer(&fq->timer))
141 continue;
142
143 hlist_add_head(&fq->list_evictor, &expired);
144 ++evicted;
145 }
146
147 spin_unlock(&hb->chain_lock);
148
149 hlist_for_each_entry_safe(fq, n, &expired, list_evictor)
150 f->frag_expire((unsigned long) fq);
151
152 return evicted;
153 }
154
155 static void inet_frag_worker(struct work_struct *work)
156 {
157 unsigned int budget = INETFRAGS_EVICT_BUCKETS;
158 unsigned int i, evicted = 0;
159 struct inet_frags *f;
160
161 f = container_of(work, struct inet_frags, frags_work);
162
163 BUILD_BUG_ON(INETFRAGS_EVICT_BUCKETS >= INETFRAGS_HASHSZ);
164
165 local_bh_disable();
166
167 for (i = ACCESS_ONCE(f->next_bucket); budget; --budget) {
168 evicted += inet_evict_bucket(f, &f->hash[i]);
169 i = (i + 1) & (INETFRAGS_HASHSZ - 1);
170 if (evicted > INETFRAGS_EVICT_MAX)
171 break;
172 }
173
174 f->next_bucket = i;
175
176 local_bh_enable();
177
178 if (f->rebuild && inet_frag_may_rebuild(f))
179 inet_frag_secret_rebuild(f);
180 }
181
182 static void inet_frag_schedule_worker(struct inet_frags *f)
183 {
184 if (unlikely(!work_pending(&f->frags_work)))
185 schedule_work(&f->frags_work);
186 }
187
188 int inet_frags_init(struct inet_frags *f)
189 {
190 int i;
191
192 INIT_WORK(&f->frags_work, inet_frag_worker);
193
194 for (i = 0; i < INETFRAGS_HASHSZ; i++) {
195 struct inet_frag_bucket *hb = &f->hash[i];
196
197 spin_lock_init(&hb->chain_lock);
198 INIT_HLIST_HEAD(&hb->chain);
199 }
200
201 seqlock_init(&f->rnd_seqlock);
202 f->last_rebuild_jiffies = 0;
203 f->frags_cachep = kmem_cache_create(f->frags_cache_name, f->qsize, 0, 0,
204 NULL);
205 if (!f->frags_cachep)
206 return -ENOMEM;
207
208 return 0;
209 }
210 EXPORT_SYMBOL(inet_frags_init);
211
212 void inet_frags_fini(struct inet_frags *f)
213 {
214 cancel_work_sync(&f->frags_work);
215 kmem_cache_destroy(f->frags_cachep);
216 }
217 EXPORT_SYMBOL(inet_frags_fini);
218
219 void inet_frags_exit_net(struct netns_frags *nf, struct inet_frags *f)
220 {
221 unsigned int seq;
222 int i;
223
224 nf->low_thresh = 0;
225
226 evict_again:
227 local_bh_disable();
228 seq = read_seqbegin(&f->rnd_seqlock);
229
230 for (i = 0; i < INETFRAGS_HASHSZ ; i++)
231 inet_evict_bucket(f, &f->hash[i]);
232
233 local_bh_enable();
234 cond_resched();
235
236 if (read_seqretry(&f->rnd_seqlock, seq) ||
237 percpu_counter_sum(&nf->mem))
238 goto evict_again;
239
240 percpu_counter_destroy(&nf->mem);
241 }
242 EXPORT_SYMBOL(inet_frags_exit_net);
243
244 static struct inet_frag_bucket *
245 get_frag_bucket_locked(struct inet_frag_queue *fq, struct inet_frags *f)
246 __acquires(hb->chain_lock)
247 {
248 struct inet_frag_bucket *hb;
249 unsigned int seq, hash;
250
251 restart:
252 seq = read_seqbegin(&f->rnd_seqlock);
253
254 hash = inet_frag_hashfn(f, fq);
255 hb = &f->hash[hash];
256
257 spin_lock(&hb->chain_lock);
258 if (read_seqretry(&f->rnd_seqlock, seq)) {
259 spin_unlock(&hb->chain_lock);
260 goto restart;
261 }
262
263 return hb;
264 }
265
266 static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
267 {
268 struct inet_frag_bucket *hb;
269
270 hb = get_frag_bucket_locked(fq, f);
271 hlist_del(&fq->list);
272 fq->flags |= INET_FRAG_COMPLETE;
273 spin_unlock(&hb->chain_lock);
274 }
275
276 void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
277 {
278 if (del_timer(&fq->timer))
279 atomic_dec(&fq->refcnt);
280
281 if (!(fq->flags & INET_FRAG_COMPLETE)) {
282 fq_unlink(fq, f);
283 atomic_dec(&fq->refcnt);
284 }
285 }
286 EXPORT_SYMBOL(inet_frag_kill);
287
288 void inet_frag_destroy(struct inet_frag_queue *q, struct inet_frags *f)
289 {
290 struct sk_buff *fp;
291 struct netns_frags *nf;
292 unsigned int sum, sum_truesize = 0;
293
294 WARN_ON(!(q->flags & INET_FRAG_COMPLETE));
295 WARN_ON(del_timer(&q->timer) != 0);
296
297 /* Release all fragment data. */
298 fp = q->fragments;
299 nf = q->net;
300 while (fp) {
301 struct sk_buff *xp = fp->next;
302
303 sum_truesize += fp->truesize;
304 kfree_skb(fp);
305 fp = xp;
306 }
307 sum = sum_truesize + f->qsize;
308
309 if (f->destructor)
310 f->destructor(q);
311 kmem_cache_free(f->frags_cachep, q);
312
313 sub_frag_mem_limit(nf, sum);
314 }
315 EXPORT_SYMBOL(inet_frag_destroy);
316
317 static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf,
318 struct inet_frag_queue *qp_in,
319 struct inet_frags *f,
320 void *arg)
321 {
322 struct inet_frag_bucket *hb = get_frag_bucket_locked(qp_in, f);
323 struct inet_frag_queue *qp;
324
325 #ifdef CONFIG_SMP
326 /* With SMP race we have to recheck hash table, because
327 * such entry could have been created on other cpu before
328 * we acquired hash bucket lock.
329 */
330 hlist_for_each_entry(qp, &hb->chain, list) {
331 if (qp->net == nf && f->match(qp, arg)) {
332 atomic_inc(&qp->refcnt);
333 spin_unlock(&hb->chain_lock);
334 qp_in->flags |= INET_FRAG_COMPLETE;
335 inet_frag_put(qp_in, f);
336 return qp;
337 }
338 }
339 #endif
340 qp = qp_in;
341 if (!mod_timer(&qp->timer, jiffies + nf->timeout))
342 atomic_inc(&qp->refcnt);
343
344 atomic_inc(&qp->refcnt);
345 hlist_add_head(&qp->list, &hb->chain);
346
347 spin_unlock(&hb->chain_lock);
348
349 return qp;
350 }
351
352 static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,
353 struct inet_frags *f,
354 void *arg)
355 {
356 struct inet_frag_queue *q;
357
358 if (frag_mem_limit(nf) > nf->high_thresh) {
359 inet_frag_schedule_worker(f);
360 return NULL;
361 }
362
363 q = kmem_cache_zalloc(f->frags_cachep, GFP_ATOMIC);
364 if (!q)
365 return NULL;
366
367 q->net = nf;
368 f->constructor(q, arg);
369 add_frag_mem_limit(nf, f->qsize);
370
371 setup_timer(&q->timer, f->frag_expire, (unsigned long)q);
372 spin_lock_init(&q->lock);
373 atomic_set(&q->refcnt, 1);
374
375 return q;
376 }
377
378 static struct inet_frag_queue *inet_frag_create(struct netns_frags *nf,
379 struct inet_frags *f,
380 void *arg)
381 {
382 struct inet_frag_queue *q;
383
384 q = inet_frag_alloc(nf, f, arg);
385 if (!q)
386 return NULL;
387
388 return inet_frag_intern(nf, q, f, arg);
389 }
390
391 struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
392 struct inet_frags *f, void *key,
393 unsigned int hash)
394 {
395 struct inet_frag_bucket *hb;
396 struct inet_frag_queue *q;
397 int depth = 0;
398
399 if (frag_mem_limit(nf) > nf->low_thresh)
400 inet_frag_schedule_worker(f);
401
402 hash &= (INETFRAGS_HASHSZ - 1);
403 hb = &f->hash[hash];
404
405 spin_lock(&hb->chain_lock);
406 hlist_for_each_entry(q, &hb->chain, list) {
407 if (q->net == nf && f->match(q, key)) {
408 atomic_inc(&q->refcnt);
409 spin_unlock(&hb->chain_lock);
410 return q;
411 }
412 depth++;
413 }
414 spin_unlock(&hb->chain_lock);
415
416 if (depth <= INETFRAGS_MAXDEPTH)
417 return inet_frag_create(nf, f, key);
418
419 if (inet_frag_may_rebuild(f)) {
420 if (!f->rebuild)
421 f->rebuild = true;
422 inet_frag_schedule_worker(f);
423 }
424
425 return ERR_PTR(-ENOBUFS);
426 }
427 EXPORT_SYMBOL(inet_frag_find);
428
429 void inet_frag_maybe_warn_overflow(struct inet_frag_queue *q,
430 const char *prefix)
431 {
432 static const char msg[] = "inet_frag_find: Fragment hash bucket"
433 " list length grew over limit " __stringify(INETFRAGS_MAXDEPTH)
434 ". Dropping fragment.\n";
435
436 if (PTR_ERR(q) == -ENOBUFS)
437 net_dbg_ratelimited("%s%s", prefix, msg);
438 }
439 EXPORT_SYMBOL(inet_frag_maybe_warn_overflow);
Linux with added FPC-III support