1 /* flow.c: Generic flow cache.
2 *
3 * Copyright (C) 2003 Alexey N. Kuznetsov (kuznet@ms2.inr.ac.ru)
4 * Copyright (C) 2003 David S. Miller (davem@redhat.com)
5 */
6
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/list.h>
10 #include <linux/jhash.h>
11 #include <linux/interrupt.h>
12 #include <linux/mm.h>
13 #include <linux/random.h>
14 #include <linux/init.h>
15 #include <linux/slab.h>
16 #include <linux/smp.h>
17 #include <linux/completion.h>
18 #include <linux/percpu.h>
19 #include <linux/bitops.h>
20 #include <linux/notifier.h>
21 #include <linux/cpu.h>
22 #include <linux/cpumask.h>
23 #include <linux/mutex.h>
24 #include <net/flow.h>
25 #include <linux/atomic.h>
26 #include <linux/security.h>
27 #include <net/net_namespace.h>
28
29 struct flow_cache_entry {
30 union {
31 struct hlist_node hlist;
32 struct list_head gc_list;
33 } u;
34 struct net *net;
35 u16 family;
36 u8 dir;
37 u32 genid;
38 struct flowi key;
39 struct flow_cache_object *object;
40 };
41
42 struct flow_flush_info {
43 struct flow_cache *cache;
44 atomic_t cpuleft;
45 struct completion completion;
46 };
47
48 static struct kmem_cache *flow_cachep __read_mostly;
49
50 #define flow_cache_hash_size(cache) (1 << (cache)->hash_shift)
51 #define FLOW_HASH_RND_PERIOD (10 * 60 * HZ)
52
53 static void flow_cache_new_hashrnd(unsigned long arg)
54 {
55 struct flow_cache *fc = (void *) arg;
56 int i;
57
58 for_each_possible_cpu(i)
59 per_cpu_ptr(fc->percpu, i)->hash_rnd_recalc = 1;
60
61 fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
62 add_timer(&fc->rnd_timer);
63 }
64
65 static int flow_entry_valid(struct flow_cache_entry *fle,
66 struct netns_xfrm *xfrm)
67 {
68 if (atomic_read(&xfrm->flow_cache_genid) != fle->genid)
69 return 0;
70 if (fle->object && !fle->object->ops->check(fle->object))
71 return 0;
72 return 1;
73 }
74
75 static void flow_entry_kill(struct flow_cache_entry *fle,
76 struct netns_xfrm *xfrm)
77 {
78 if (fle->object)
79 fle->object->ops->delete(fle->object);
80 kmem_cache_free(flow_cachep, fle);
81 }
82
83 static void flow_cache_gc_task(struct work_struct *work)
84 {
85 struct list_head gc_list;
86 struct flow_cache_entry *fce, *n;
87 struct netns_xfrm *xfrm = container_of(work, struct netns_xfrm,
88 flow_cache_gc_work);
89
90 INIT_LIST_HEAD(&gc_list);
91 spin_lock_bh(&xfrm->flow_cache_gc_lock);
92 list_splice_tail_init(&xfrm->flow_cache_gc_list, &gc_list);
93 spin_unlock_bh(&xfrm->flow_cache_gc_lock);
94
95 list_for_each_entry_safe(fce, n, &gc_list, u.gc_list) {
96 flow_entry_kill(fce, xfrm);
97 atomic_dec(&xfrm->flow_cache_gc_count);
98 }
99 }
100
101 static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp,
102 int deleted, struct list_head *gc_list,
103 struct netns_xfrm *xfrm)
104 {
105 if (deleted) {
106 atomic_add(deleted, &xfrm->flow_cache_gc_count);
107 fcp->hash_count -= deleted;
108 spin_lock_bh(&xfrm->flow_cache_gc_lock);
109 list_splice_tail(gc_list, &xfrm->flow_cache_gc_list);
110 spin_unlock_bh(&xfrm->flow_cache_gc_lock);
111 schedule_work(&xfrm->flow_cache_gc_work);
112 }
113 }
114
115 static void __flow_cache_shrink(struct flow_cache *fc,
116 struct flow_cache_percpu *fcp,
117 int shrink_to)
118 {
119 struct flow_cache_entry *fle;
120 struct hlist_node *tmp;
121 LIST_HEAD(gc_list);
122 int i, deleted = 0;
123 struct netns_xfrm *xfrm = container_of(fc, struct netns_xfrm,
124 flow_cache_global);
125
126 for (i = 0; i < flow_cache_hash_size(fc); i++) {
127 int saved = 0;
128
129 hlist_for_each_entry_safe(fle, tmp,
130 &fcp->hash_table[i], u.hlist) {
131 if (saved < shrink_to &&
132 flow_entry_valid(fle, xfrm)) {
133 saved++;
134 } else {
135 deleted++;
136 hlist_del(&fle->u.hlist);
137 list_add_tail(&fle->u.gc_list, &gc_list);
138 }
139 }
140 }
141
142 flow_cache_queue_garbage(fcp, deleted, &gc_list, xfrm);
143 }
144
145 static void flow_cache_shrink(struct flow_cache *fc,
146 struct flow_cache_percpu *fcp)
147 {
148 int shrink_to = fc->low_watermark / flow_cache_hash_size(fc);
149
150 __flow_cache_shrink(fc, fcp, shrink_to);
151 }
152
153 static void flow_new_hash_rnd(struct flow_cache *fc,
154 struct flow_cache_percpu *fcp)
155 {
156 get_random_bytes(&fcp->hash_rnd, sizeof(u32));
157 fcp->hash_rnd_recalc = 0;
158 __flow_cache_shrink(fc, fcp, 0);
159 }
160
161 static u32 flow_hash_code(struct flow_cache *fc,
162 struct flow_cache_percpu *fcp,
163 const struct flowi *key,
164 size_t keysize)
165 {
166 const u32 *k = (const u32 *) key;
167 const u32 length = keysize * sizeof(flow_compare_t) / sizeof(u32);
168
169 return jhash2(k, length, fcp->hash_rnd)
170 & (flow_cache_hash_size(fc) - 1);
171 }
172
173 /* I hear what you're saying, use memcmp. But memcmp cannot make
174 * important assumptions that we can here, such as alignment.
175 */
176 static int flow_key_compare(const struct flowi *key1, const struct flowi *key2,
177 size_t keysize)
178 {
179 const flow_compare_t *k1, *k1_lim, *k2;
180
181 k1 = (const flow_compare_t *) key1;
182 k1_lim = k1 + keysize;
183
184 k2 = (const flow_compare_t *) key2;
185
186 do {
187 if (*k1++ != *k2++)
188 return 1;
189 } while (k1 < k1_lim);
190
191 return 0;
192 }
193
194 struct flow_cache_object *
195 flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
196 flow_resolve_t resolver, void *ctx)
197 {
198 struct flow_cache *fc = &net->xfrm.flow_cache_global;
199 struct flow_cache_percpu *fcp;
200 struct flow_cache_entry *fle, *tfle;
201 struct flow_cache_object *flo;
202 size_t keysize;
203 unsigned int hash;
204
205 local_bh_disable();
206 fcp = this_cpu_ptr(fc->percpu);
207
208 fle = NULL;
209 flo = NULL;
210
211 keysize = flow_key_size(family);
212 if (!keysize)
213 goto nocache;
214
215 /* Packet really early in init? Making flow_cache_init a
216 * pre-smp initcall would solve this. --RR */
217 if (!fcp->hash_table)
218 goto nocache;
219
220 if (fcp->hash_rnd_recalc)
221 flow_new_hash_rnd(fc, fcp);
222
223 hash = flow_hash_code(fc, fcp, key, keysize);
224 hlist_for_each_entry(tfle, &fcp->hash_table[hash], u.hlist) {
225 if (tfle->net == net &&
226 tfle->family == family &&
227 tfle->dir == dir &&
228 flow_key_compare(key, &tfle->key, keysize) == 0) {
229 fle = tfle;
230 break;
231 }
232 }
233
234 if (unlikely(!fle)) {
235 if (fcp->hash_count > fc->high_watermark)
236 flow_cache_shrink(fc, fcp);
237
238 if (atomic_read(&net->xfrm.flow_cache_gc_count) >
239 2 * num_online_cpus() * fc->high_watermark) {
240 flo = ERR_PTR(-ENOBUFS);
241 goto ret_object;
242 }
243
244 fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
245 if (fle) {
246 fle->net = net;
247 fle->family = family;
248 fle->dir = dir;
249 memcpy(&fle->key, key, keysize * sizeof(flow_compare_t));
250 fle->object = NULL;
251 hlist_add_head(&fle->u.hlist, &fcp->hash_table[hash]);
252 fcp->hash_count++;
253 }
254 } else if (likely(fle->genid == atomic_read(&net->xfrm.flow_cache_genid))) {
255 flo = fle->object;
256 if (!flo)
257 goto ret_object;
258 flo = flo->ops->get(flo);
259 if (flo)
260 goto ret_object;
261 } else if (fle->object) {
262 flo = fle->object;
263 flo->ops->delete(flo);
264 fle->object = NULL;
265 }
266
267 nocache:
268 flo = NULL;
269 if (fle) {
270 flo = fle->object;
271 fle->object = NULL;
272 }
273 flo = resolver(net, key, family, dir, flo, ctx);
274 if (fle) {
275 fle->genid = atomic_read(&net->xfrm.flow_cache_genid);
276 if (!IS_ERR(flo))
277 fle->object = flo;
278 else
279 fle->genid--;
280 } else {
281 if (!IS_ERR_OR_NULL(flo))
282 flo->ops->delete(flo);
283 }
284 ret_object:
285 local_bh_enable();
286 return flo;
287 }
288 EXPORT_SYMBOL(flow_cache_lookup);
289
290 static void flow_cache_flush_tasklet(unsigned long data)
291 {
292 struct flow_flush_info *info = (void *)data;
293 struct flow_cache *fc = info->cache;
294 struct flow_cache_percpu *fcp;
295 struct flow_cache_entry *fle;
296 struct hlist_node *tmp;
297 LIST_HEAD(gc_list);
298 int i, deleted = 0;
299 struct netns_xfrm *xfrm = container_of(fc, struct netns_xfrm,
300 flow_cache_global);
301
302 fcp = this_cpu_ptr(fc->percpu);
303 for (i = 0; i < flow_cache_hash_size(fc); i++) {
304 hlist_for_each_entry_safe(fle, tmp,
305 &fcp->hash_table[i], u.hlist) {
306 if (flow_entry_valid(fle, xfrm))
307 continue;
308
309 deleted++;
310 hlist_del(&fle->u.hlist);
311 list_add_tail(&fle->u.gc_list, &gc_list);
312 }
313 }
314
315 flow_cache_queue_garbage(fcp, deleted, &gc_list, xfrm);
316
317 if (atomic_dec_and_test(&info->cpuleft))
318 complete(&info->completion);
319 }
320
321 /*
322 * Return whether a cpu needs flushing. Conservatively, we assume
323 * the presence of any entries means the core may require flushing,
324 * since the flow_cache_ops.check() function may assume it's running
325 * on the same core as the per-cpu cache component.
326 */
327 static int flow_cache_percpu_empty(struct flow_cache *fc, int cpu)
328 {
329 struct flow_cache_percpu *fcp;
330 int i;
331
332 fcp = per_cpu_ptr(fc->percpu, cpu);
333 for (i = 0; i < flow_cache_hash_size(fc); i++)
334 if (!hlist_empty(&fcp->hash_table[i]))
335 return 0;
336 return 1;
337 }
338
339 static void flow_cache_flush_per_cpu(void *data)
340 {
341 struct flow_flush_info *info = data;
342 struct tasklet_struct *tasklet;
343
344 tasklet = &this_cpu_ptr(info->cache->percpu)->flush_tasklet;
345 tasklet->data = (unsigned long)info;
346 tasklet_schedule(tasklet);
347 }
348
349 void flow_cache_flush(struct net *net)
350 {
351 struct flow_flush_info info;
352 cpumask_var_t mask;
353 int i, self;
354
355 /* Track which cpus need flushing to avoid disturbing all cores. */
356 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
357 return;
358 cpumask_clear(mask);
359
360 /* Don't want cpus going down or up during this. */
361 get_online_cpus();
362 mutex_lock(&net->xfrm.flow_flush_sem);
363 info.cache = &net->xfrm.flow_cache_global;
364 for_each_online_cpu(i)
365 if (!flow_cache_percpu_empty(info.cache, i))
366 cpumask_set_cpu(i, mask);
367 atomic_set(&info.cpuleft, cpumask_weight(mask));
368 if (atomic_read(&info.cpuleft) == 0)
369 goto done;
370
371 init_completion(&info.completion);
372
373 local_bh_disable();
374 self = cpumask_test_and_clear_cpu(smp_processor_id(), mask);
375 on_each_cpu_mask(mask, flow_cache_flush_per_cpu, &info, 0);
376 if (self)
377 flow_cache_flush_tasklet((unsigned long)&info);
378 local_bh_enable();
379
380 wait_for_completion(&info.completion);
381
382 done:
383 mutex_unlock(&net->xfrm.flow_flush_sem);
384 put_online_cpus();
385 free_cpumask_var(mask);
386 }
387
388 static void flow_cache_flush_task(struct work_struct *work)
389 {
390 struct netns_xfrm *xfrm = container_of(work, struct netns_xfrm,
391 flow_cache_flush_work);
392 struct net *net = container_of(xfrm, struct net, xfrm);
393
394 flow_cache_flush(net);
395 }
396
397 void flow_cache_flush_deferred(struct net *net)
398 {
399 schedule_work(&net->xfrm.flow_cache_flush_work);
400 }
401
402 static int flow_cache_cpu_prepare(struct flow_cache *fc, int cpu)
403 {
404 struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
405 size_t sz = sizeof(struct hlist_head) * flow_cache_hash_size(fc);
406
407 if (!fcp->hash_table) {
408 fcp->hash_table = kzalloc_node(sz, GFP_KERNEL, cpu_to_node(cpu));
409 if (!fcp->hash_table) {
410 pr_err("NET: failed to allocate flow cache sz %zu\n", sz);
411 return -ENOMEM;
412 }
413 fcp->hash_rnd_recalc = 1;
414 fcp->hash_count = 0;
415 tasklet_init(&fcp->flush_tasklet, flow_cache_flush_tasklet, 0);
416 }
417 return 0;
418 }
419
420 static int flow_cache_cpu(struct notifier_block *nfb,
421 unsigned long action,
422 void *hcpu)
423 {
424 struct flow_cache *fc = container_of(nfb, struct flow_cache,
425 hotcpu_notifier);
426 int res, cpu = (unsigned long) hcpu;
427 struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
428
429 switch (action) {
430 case CPU_UP_PREPARE:
431 case CPU_UP_PREPARE_FROZEN:
432 res = flow_cache_cpu_prepare(fc, cpu);
433 if (res)
434 return notifier_from_errno(res);
435 break;
436 case CPU_DEAD:
437 case CPU_DEAD_FROZEN:
438 __flow_cache_shrink(fc, fcp, 0);
439 break;
440 }
441 return NOTIFY_OK;
442 }
443
444 int flow_cache_init(struct net *net)
445 {
446 int i;
447 struct flow_cache *fc = &net->xfrm.flow_cache_global;
448
449 if (!flow_cachep)
450 flow_cachep = kmem_cache_create("flow_cache",
451 sizeof(struct flow_cache_entry),
452 0, SLAB_PANIC, NULL);
453 spin_lock_init(&net->xfrm.flow_cache_gc_lock);
454 INIT_LIST_HEAD(&net->xfrm.flow_cache_gc_list);
455 INIT_WORK(&net->xfrm.flow_cache_gc_work, flow_cache_gc_task);
456 INIT_WORK(&net->xfrm.flow_cache_flush_work, flow_cache_flush_task);
457 mutex_init(&net->xfrm.flow_flush_sem);
458 atomic_set(&net->xfrm.flow_cache_gc_count, 0);
459
460 fc->hash_shift = 10;
461 fc->low_watermark = 2 * flow_cache_hash_size(fc);
462 fc->high_watermark = 4 * flow_cache_hash_size(fc);
463
464 fc->percpu = alloc_percpu(struct flow_cache_percpu);
465 if (!fc->percpu)
466 return -ENOMEM;
467
468 cpu_notifier_register_begin();
469
470 for_each_online_cpu(i) {
471 if (flow_cache_cpu_prepare(fc, i))
472 goto err;
473 }
474 fc->hotcpu_notifier = (struct notifier_block){
475 .notifier_call = flow_cache_cpu,
476 };
477 __register_hotcpu_notifier(&fc->hotcpu_notifier);
478
479 cpu_notifier_register_done();
480
481 setup_timer(&fc->rnd_timer, flow_cache_new_hashrnd,
482 (unsigned long) fc);
483 fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
484 add_timer(&fc->rnd_timer);
485
486 return 0;
487
488 err:
489 for_each_possible_cpu(i) {
490 struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, i);
491 kfree(fcp->hash_table);
492 fcp->hash_table = NULL;
493 }
494
495 cpu_notifier_register_done();
496
497 free_percpu(fc->percpu);
498 fc->percpu = NULL;
499
500 return -ENOMEM;
501 }
502 EXPORT_SYMBOL(flow_cache_init);
503
504 void flow_cache_fini(struct net *net)
505 {
506 int i;
507 struct flow_cache *fc = &net->xfrm.flow_cache_global;
508
509 del_timer_sync(&fc->rnd_timer);
510 unregister_hotcpu_notifier(&fc->hotcpu_notifier);
511
512 for_each_possible_cpu(i) {
513 struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, i);
514 kfree(fcp->hash_table);
515 fcp->hash_table = NULL;
516 }
517
518 free_percpu(fc->percpu);
519 fc->percpu = NULL;
520 }
521 EXPORT_SYMBOL(flow_cache_fini);
522
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