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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
29struct 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
42struct flow_flush_info {
43 struct flow_cache *cache;
44 atomic_t cpuleft;
45 struct completion completion;
46};
47
48static 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
53static 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
65static 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
75static 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
83static 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 WARN_ON(atomic_read(&xfrm->flow_cache_gc_count) < 0);
99 }
100}
101
102static void flow_cache_queue_garbage(struct flow_cache_percpu *fcp,
103 int deleted, struct list_head *gc_list,
104 struct netns_xfrm *xfrm)
105{
106 if (deleted) {
107 atomic_add(deleted, &xfrm->flow_cache_gc_count);
108 fcp->hash_count -= deleted;
109 spin_lock_bh(&xfrm->flow_cache_gc_lock);
110 list_splice_tail(gc_list, &xfrm->flow_cache_gc_list);
111 spin_unlock_bh(&xfrm->flow_cache_gc_lock);
112 schedule_work(&xfrm->flow_cache_gc_work);
113 }
114}
115
116static void __flow_cache_shrink(struct flow_cache *fc,
117 struct flow_cache_percpu *fcp,
118 int shrink_to)
119{
120 struct flow_cache_entry *fle;
121 struct hlist_node *tmp;
122 LIST_HEAD(gc_list);
123 int i, deleted = 0;
124 struct netns_xfrm *xfrm = container_of(fc, struct netns_xfrm,
125 flow_cache_global);
126
127 for (i = 0; i < flow_cache_hash_size(fc); i++) {
128 int saved = 0;
129
130 hlist_for_each_entry_safe(fle, tmp,
131 &fcp->hash_table[i], u.hlist) {
132 if (saved < shrink_to &&
133 flow_entry_valid(fle, xfrm)) {
134 saved++;
135 } else {
136 deleted++;
137 hlist_del(&fle->u.hlist);
138 list_add_tail(&fle->u.gc_list, &gc_list);
139 }
140 }
141 }
142
143 flow_cache_queue_garbage(fcp, deleted, &gc_list, xfrm);
144}
145
146static void flow_cache_shrink(struct flow_cache *fc,
147 struct flow_cache_percpu *fcp)
148{
149 int shrink_to = fc->low_watermark / flow_cache_hash_size(fc);
150
151 __flow_cache_shrink(fc, fcp, shrink_to);
152}
153
154static void flow_new_hash_rnd(struct flow_cache *fc,
155 struct flow_cache_percpu *fcp)
156{
157 get_random_bytes(&fcp->hash_rnd, sizeof(u32));
158 fcp->hash_rnd_recalc = 0;
159 __flow_cache_shrink(fc, fcp, 0);
160}
161
162static u32 flow_hash_code(struct flow_cache *fc,
163 struct flow_cache_percpu *fcp,
164 const struct flowi *key,
165 size_t keysize)
166{
167 const u32 *k = (const u32 *) key;
168 const u32 length = keysize * sizeof(flow_compare_t) / sizeof(u32);
169
170 return jhash2(k, length, fcp->hash_rnd)
171 & (flow_cache_hash_size(fc) - 1);
172}
173
174/* I hear what you're saying, use memcmp. But memcmp cannot make
175 * important assumptions that we can here, such as alignment.
176 */
177static int flow_key_compare(const struct flowi *key1, const struct flowi *key2,
178 size_t keysize)
179{
180 const flow_compare_t *k1, *k1_lim, *k2;
181
182 k1 = (const flow_compare_t *) key1;
183 k1_lim = k1 + keysize;
184
185 k2 = (const flow_compare_t *) key2;
186
187 do {
188 if (*k1++ != *k2++)
189 return 1;
190 } while (k1 < k1_lim);
191
192 return 0;
193}
194
195struct flow_cache_object *
196flow_cache_lookup(struct net *net, const struct flowi *key, u16 family, u8 dir,
197 flow_resolve_t resolver, void *ctx)
198{
199 struct flow_cache *fc = &net->xfrm.flow_cache_global;
200 struct flow_cache_percpu *fcp;
201 struct flow_cache_entry *fle, *tfle;
202 struct flow_cache_object *flo;
203 size_t keysize;
204 unsigned int hash;
205
206 local_bh_disable();
207 fcp = this_cpu_ptr(fc->percpu);
208
209 fle = NULL;
210 flo = NULL;
211
212 keysize = flow_key_size(family);
213 if (!keysize)
214 goto nocache;
215
216 /* Packet really early in init? Making flow_cache_init a
217 * pre-smp initcall would solve this. --RR */
218 if (!fcp->hash_table)
219 goto nocache;
220
221 if (fcp->hash_rnd_recalc)
222 flow_new_hash_rnd(fc, fcp);
223
224 hash = flow_hash_code(fc, fcp, key, keysize);
225 hlist_for_each_entry(tfle, &fcp->hash_table[hash], u.hlist) {
226 if (tfle->net == net &&
227 tfle->family == family &&
228 tfle->dir == dir &&
229 flow_key_compare(key, &tfle->key, keysize) == 0) {
230 fle = tfle;
231 break;
232 }
233 }
234
235 if (unlikely(!fle)) {
236 if (fcp->hash_count > fc->high_watermark)
237 flow_cache_shrink(fc, fcp);
238
239 if (fcp->hash_count > 2 * fc->high_watermark ||
240 atomic_read(&net->xfrm.flow_cache_gc_count) > fc->high_watermark) {
241 atomic_inc(&net->xfrm.flow_cache_genid);
242 flo = ERR_PTR(-ENOBUFS);
243 goto ret_object;
244 }
245
246 fle = kmem_cache_alloc(flow_cachep, GFP_ATOMIC);
247 if (fle) {
248 fle->net = net;
249 fle->family = family;
250 fle->dir = dir;
251 memcpy(&fle->key, key, keysize * sizeof(flow_compare_t));
252 fle->object = NULL;
253 hlist_add_head(&fle->u.hlist, &fcp->hash_table[hash]);
254 fcp->hash_count++;
255 }
256 } else if (likely(fle->genid == atomic_read(&net->xfrm.flow_cache_genid))) {
257 flo = fle->object;
258 if (!flo)
259 goto ret_object;
260 flo = flo->ops->get(flo);
261 if (flo)
262 goto ret_object;
263 } else if (fle->object) {
264 flo = fle->object;
265 flo->ops->delete(flo);
266 fle->object = NULL;
267 }
268
269nocache:
270 flo = NULL;
271 if (fle) {
272 flo = fle->object;
273 fle->object = NULL;
274 }
275 flo = resolver(net, key, family, dir, flo, ctx);
276 if (fle) {
277 fle->genid = atomic_read(&net->xfrm.flow_cache_genid);
278 if (!IS_ERR(flo))
279 fle->object = flo;
280 else
281 fle->genid--;
282 } else {
283 if (!IS_ERR_OR_NULL(flo))
284 flo->ops->delete(flo);
285 }
286ret_object:
287 local_bh_enable();
288 return flo;
289}
290EXPORT_SYMBOL(flow_cache_lookup);
291
292static void flow_cache_flush_tasklet(unsigned long data)
293{
294 struct flow_flush_info *info = (void *)data;
295 struct flow_cache *fc = info->cache;
296 struct flow_cache_percpu *fcp;
297 struct flow_cache_entry *fle;
298 struct hlist_node *tmp;
299 LIST_HEAD(gc_list);
300 int i, deleted = 0;
301 struct netns_xfrm *xfrm = container_of(fc, struct netns_xfrm,
302 flow_cache_global);
303
304 fcp = this_cpu_ptr(fc->percpu);
305 for (i = 0; i < flow_cache_hash_size(fc); i++) {
306 hlist_for_each_entry_safe(fle, tmp,
307 &fcp->hash_table[i], u.hlist) {
308 if (flow_entry_valid(fle, xfrm))
309 continue;
310
311 deleted++;
312 hlist_del(&fle->u.hlist);
313 list_add_tail(&fle->u.gc_list, &gc_list);
314 }
315 }
316
317 flow_cache_queue_garbage(fcp, deleted, &gc_list, xfrm);
318
319 if (atomic_dec_and_test(&info->cpuleft))
320 complete(&info->completion);
321}
322
323/*
324 * Return whether a cpu needs flushing. Conservatively, we assume
325 * the presence of any entries means the core may require flushing,
326 * since the flow_cache_ops.check() function may assume it's running
327 * on the same core as the per-cpu cache component.
328 */
329static int flow_cache_percpu_empty(struct flow_cache *fc, int cpu)
330{
331 struct flow_cache_percpu *fcp;
332 int i;
333
334 fcp = per_cpu_ptr(fc->percpu, cpu);
335 for (i = 0; i < flow_cache_hash_size(fc); i++)
336 if (!hlist_empty(&fcp->hash_table[i]))
337 return 0;
338 return 1;
339}
340
341static void flow_cache_flush_per_cpu(void *data)
342{
343 struct flow_flush_info *info = data;
344 struct tasklet_struct *tasklet;
345
346 tasklet = &this_cpu_ptr(info->cache->percpu)->flush_tasklet;
347 tasklet->data = (unsigned long)info;
348 tasklet_schedule(tasklet);
349}
350
351void flow_cache_flush(struct net *net)
352{
353 struct flow_flush_info info;
354 cpumask_var_t mask;
355 int i, self;
356
357 /* Track which cpus need flushing to avoid disturbing all cores. */
358 if (!alloc_cpumask_var(&mask, GFP_KERNEL))
359 return;
360 cpumask_clear(mask);
361
362 /* Don't want cpus going down or up during this. */
363 get_online_cpus();
364 mutex_lock(&net->xfrm.flow_flush_sem);
365 info.cache = &net->xfrm.flow_cache_global;
366 for_each_online_cpu(i)
367 if (!flow_cache_percpu_empty(info.cache, i))
368 cpumask_set_cpu(i, mask);
369 atomic_set(&info.cpuleft, cpumask_weight(mask));
370 if (atomic_read(&info.cpuleft) == 0)
371 goto done;
372
373 init_completion(&info.completion);
374
375 local_bh_disable();
376 self = cpumask_test_and_clear_cpu(smp_processor_id(), mask);
377 on_each_cpu_mask(mask, flow_cache_flush_per_cpu, &info, 0);
378 if (self)
379 flow_cache_flush_tasklet((unsigned long)&info);
380 local_bh_enable();
381
382 wait_for_completion(&info.completion);
383
384done:
385 mutex_unlock(&net->xfrm.flow_flush_sem);
386 put_online_cpus();
387 free_cpumask_var(mask);
388}
389
390static void flow_cache_flush_task(struct work_struct *work)
391{
392 struct netns_xfrm *xfrm = container_of(work, struct netns_xfrm,
393 flow_cache_flush_work);
394 struct net *net = container_of(xfrm, struct net, xfrm);
395
396 flow_cache_flush(net);
397}
398
399void flow_cache_flush_deferred(struct net *net)
400{
401 schedule_work(&net->xfrm.flow_cache_flush_work);
402}
403
404static int flow_cache_cpu_prepare(struct flow_cache *fc, int cpu)
405{
406 struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
407 size_t sz = sizeof(struct hlist_head) * flow_cache_hash_size(fc);
408
409 if (!fcp->hash_table) {
410 fcp->hash_table = kzalloc_node(sz, GFP_KERNEL, cpu_to_node(cpu));
411 if (!fcp->hash_table) {
412 pr_err("NET: failed to allocate flow cache sz %zu\n", sz);
413 return -ENOMEM;
414 }
415 fcp->hash_rnd_recalc = 1;
416 fcp->hash_count = 0;
417 tasklet_init(&fcp->flush_tasklet, flow_cache_flush_tasklet, 0);
418 }
419 return 0;
420}
421
422static int flow_cache_cpu(struct notifier_block *nfb,
423 unsigned long action,
424 void *hcpu)
425{
426 struct flow_cache *fc = container_of(nfb, struct flow_cache,
427 hotcpu_notifier);
428 int res, cpu = (unsigned long) hcpu;
429 struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, cpu);
430
431 switch (action) {
432 case CPU_UP_PREPARE:
433 case CPU_UP_PREPARE_FROZEN:
434 res = flow_cache_cpu_prepare(fc, cpu);
435 if (res)
436 return notifier_from_errno(res);
437 break;
438 case CPU_DEAD:
439 case CPU_DEAD_FROZEN:
440 __flow_cache_shrink(fc, fcp, 0);
441 break;
442 }
443 return NOTIFY_OK;
444}
445
446int flow_cache_init(struct net *net)
447{
448 int i;
449 struct flow_cache *fc = &net->xfrm.flow_cache_global;
450
451 if (!flow_cachep)
452 flow_cachep = kmem_cache_create("flow_cache",
453 sizeof(struct flow_cache_entry),
454 0, SLAB_PANIC, NULL);
455 spin_lock_init(&net->xfrm.flow_cache_gc_lock);
456 INIT_LIST_HEAD(&net->xfrm.flow_cache_gc_list);
457 INIT_WORK(&net->xfrm.flow_cache_gc_work, flow_cache_gc_task);
458 INIT_WORK(&net->xfrm.flow_cache_flush_work, flow_cache_flush_task);
459 mutex_init(&net->xfrm.flow_flush_sem);
460 atomic_set(&net->xfrm.flow_cache_gc_count, 0);
461
462 fc->hash_shift = 10;
463 fc->low_watermark = 2 * flow_cache_hash_size(fc);
464 fc->high_watermark = 4 * flow_cache_hash_size(fc);
465
466 fc->percpu = alloc_percpu(struct flow_cache_percpu);
467 if (!fc->percpu)
468 return -ENOMEM;
469
470 cpu_notifier_register_begin();
471
472 for_each_online_cpu(i) {
473 if (flow_cache_cpu_prepare(fc, i))
474 goto err;
475 }
476 fc->hotcpu_notifier = (struct notifier_block){
477 .notifier_call = flow_cache_cpu,
478 };
479 __register_hotcpu_notifier(&fc->hotcpu_notifier);
480
481 cpu_notifier_register_done();
482
483 setup_timer(&fc->rnd_timer, flow_cache_new_hashrnd,
484 (unsigned long) fc);
485 fc->rnd_timer.expires = jiffies + FLOW_HASH_RND_PERIOD;
486 add_timer(&fc->rnd_timer);
487
488 return 0;
489
490err:
491 for_each_possible_cpu(i) {
492 struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, i);
493 kfree(fcp->hash_table);
494 fcp->hash_table = NULL;
495 }
496
497 cpu_notifier_register_done();
498
499 free_percpu(fc->percpu);
500 fc->percpu = NULL;
501
502 return -ENOMEM;
503}
504EXPORT_SYMBOL(flow_cache_init);
505
506void flow_cache_fini(struct net *net)
507{
508 int i;
509 struct flow_cache *fc = &net->xfrm.flow_cache_global;
510
511 del_timer_sync(&fc->rnd_timer);
512 unregister_hotcpu_notifier(&fc->hotcpu_notifier);
513
514 for_each_possible_cpu(i) {
515 struct flow_cache_percpu *fcp = per_cpu_ptr(fc->percpu, i);
516 kfree(fcp->hash_table);
517 fcp->hash_table = NULL;
518 }
519
520 free_percpu(fc->percpu);
521 fc->percpu = NULL;
522}
523EXPORT_SYMBOL(flow_cache_fini);