1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
|
/*
* count the number of connections matching an arbitrary key.
*
* (C) 2017 Red Hat GmbH
* Author: Florian Westphal <fw@strlen.de>
*
* split from xt_connlimit.c:
* (c) 2000 Gerd Knorr <kraxel@bytesex.org>
* Nov 2002: Martin Bene <martin.bene@icomedias.com>:
* only ignore TIME_WAIT or gone connections
* (C) CC Computer Consultants GmbH, 2007
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/in.h>
#include <linux/in6.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/jhash.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/rbtree.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/skbuff.h>
#include <linux/spinlock.h>
#include <linux/netfilter/nf_conntrack_tcp.h>
#include <linux/netfilter/x_tables.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_count.h>
#include <net/netfilter/nf_conntrack_core.h>
#include <net/netfilter/nf_conntrack_tuple.h>
#include <net/netfilter/nf_conntrack_zones.h>
#define CONNCOUNT_SLOTS 256U
#define CONNCOUNT_GC_MAX_NODES 8
#define MAX_KEYLEN 5
/* we will save the tuples of all connections we care about */
struct nf_conncount_tuple {
struct list_head node;
struct nf_conntrack_tuple tuple;
struct nf_conntrack_zone zone;
int cpu;
u32 jiffies32;
bool dead;
struct rcu_head rcu_head;
};
struct nf_conncount_rb {
struct rb_node node;
struct nf_conncount_list list;
u32 key[MAX_KEYLEN];
struct rcu_head rcu_head;
};
static spinlock_t nf_conncount_locks[CONNCOUNT_SLOTS] __cacheline_aligned_in_smp;
struct nf_conncount_data {
unsigned int keylen;
struct rb_root root[CONNCOUNT_SLOTS];
struct net *net;
struct work_struct gc_work;
unsigned long pending_trees[BITS_TO_LONGS(CONNCOUNT_SLOTS)];
unsigned int gc_tree;
};
static u_int32_t conncount_rnd __read_mostly;
static struct kmem_cache *conncount_rb_cachep __read_mostly;
static struct kmem_cache *conncount_conn_cachep __read_mostly;
static inline bool already_closed(const struct nf_conn *conn)
{
if (nf_ct_protonum(conn) == IPPROTO_TCP)
return conn->proto.tcp.state == TCP_CONNTRACK_TIME_WAIT ||
conn->proto.tcp.state == TCP_CONNTRACK_CLOSE;
else
return false;
}
static int key_diff(const u32 *a, const u32 *b, unsigned int klen)
{
return memcmp(a, b, klen * sizeof(u32));
}
static void __conn_free(struct rcu_head *h)
{
struct nf_conncount_tuple *conn;
conn = container_of(h, struct nf_conncount_tuple, rcu_head);
kmem_cache_free(conncount_conn_cachep, conn);
}
static bool conn_free(struct nf_conncount_list *list,
struct nf_conncount_tuple *conn)
{
bool free_entry = false;
spin_lock_bh(&list->list_lock);
if (conn->dead) {
spin_unlock_bh(&list->list_lock);
return free_entry;
}
list->count--;
conn->dead = true;
list_del_rcu(&conn->node);
if (list->count == 0) {
list->dead = true;
free_entry = true;
}
spin_unlock_bh(&list->list_lock);
call_rcu(&conn->rcu_head, __conn_free);
return free_entry;
}
static const struct nf_conntrack_tuple_hash *
find_or_evict(struct net *net, struct nf_conncount_list *list,
struct nf_conncount_tuple *conn, bool *free_entry)
{
const struct nf_conntrack_tuple_hash *found;
unsigned long a, b;
int cpu = raw_smp_processor_id();
u32 age;
found = nf_conntrack_find_get(net, &conn->zone, &conn->tuple);
if (found)
return found;
b = conn->jiffies32;
a = (u32)jiffies;
/* conn might have been added just before by another cpu and
* might still be unconfirmed. In this case, nf_conntrack_find()
* returns no result. Thus only evict if this cpu added the
* stale entry or if the entry is older than two jiffies.
*/
age = a - b;
if (conn->cpu == cpu || age >= 2) {
*free_entry = conn_free(list, conn);
return ERR_PTR(-ENOENT);
}
return ERR_PTR(-EAGAIN);
}
static int __nf_conncount_add(struct net *net,
struct nf_conncount_list *list,
const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone)
{
const struct nf_conntrack_tuple_hash *found;
struct nf_conncount_tuple *conn, *conn_n;
struct nf_conn *found_ct;
unsigned int collect = 0;
bool free_entry = false;
/* check the saved connections */
list_for_each_entry_safe(conn, conn_n, &list->head, node) {
if (collect > CONNCOUNT_GC_MAX_NODES)
break;
found = find_or_evict(net, list, conn, &free_entry);
if (IS_ERR(found)) {
/* Not found, but might be about to be confirmed */
if (PTR_ERR(found) == -EAGAIN) {
if (nf_ct_tuple_equal(&conn->tuple, tuple) &&
nf_ct_zone_id(&conn->zone, conn->zone.dir) ==
nf_ct_zone_id(zone, zone->dir))
return 0; /* already exists */
} else {
collect++;
}
continue;
}
found_ct = nf_ct_tuplehash_to_ctrack(found);
if (nf_ct_tuple_equal(&conn->tuple, tuple) &&
nf_ct_zone_equal(found_ct, zone, zone->dir)) {
/*
* We should not see tuples twice unless someone hooks
* this into a table without "-p tcp --syn".
*
* Attempt to avoid a re-add in this case.
*/
nf_ct_put(found_ct);
return 0;
} else if (already_closed(found_ct)) {
/*
* we do not care about connections which are
* closed already -> ditch it
*/
nf_ct_put(found_ct);
conn_free(list, conn);
collect++;
continue;
}
nf_ct_put(found_ct);
}
if (WARN_ON_ONCE(list->count > INT_MAX))
return -EOVERFLOW;
conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC);
if (conn == NULL)
return -ENOMEM;
conn->tuple = *tuple;
conn->zone = *zone;
conn->cpu = raw_smp_processor_id();
conn->jiffies32 = (u32)jiffies;
list_add_tail(&conn->node, &list->head);
list->count++;
return 0;
}
int nf_conncount_add(struct net *net,
struct nf_conncount_list *list,
const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone)
{
int ret;
/* check the saved connections */
spin_lock_bh(&list->list_lock);
ret = __nf_conncount_add(net, list, tuple, zone);
spin_unlock_bh(&list->list_lock);
return ret;
}
EXPORT_SYMBOL_GPL(nf_conncount_add);
void nf_conncount_list_init(struct nf_conncount_list *list)
{
spin_lock_init(&list->list_lock);
INIT_LIST_HEAD(&list->head);
list->count = 0;
list->dead = false;
}
EXPORT_SYMBOL_GPL(nf_conncount_list_init);
/* Return true if the list is empty */
bool nf_conncount_gc_list(struct net *net,
struct nf_conncount_list *list)
{
const struct nf_conntrack_tuple_hash *found;
struct nf_conncount_tuple *conn, *conn_n;
struct nf_conn *found_ct;
unsigned int collected = 0;
bool free_entry = false;
bool ret = false;
list_for_each_entry_safe(conn, conn_n, &list->head, node) {
found = find_or_evict(net, list, conn, &free_entry);
if (IS_ERR(found)) {
if (PTR_ERR(found) == -ENOENT) {
if (free_entry)
return true;
collected++;
}
continue;
}
found_ct = nf_ct_tuplehash_to_ctrack(found);
if (already_closed(found_ct)) {
/*
* we do not care about connections which are
* closed already -> ditch it
*/
nf_ct_put(found_ct);
if (conn_free(list, conn))
return true;
collected++;
continue;
}
nf_ct_put(found_ct);
if (collected > CONNCOUNT_GC_MAX_NODES)
return false;
}
spin_lock_bh(&list->list_lock);
if (!list->count) {
list->dead = true;
ret = true;
}
spin_unlock_bh(&list->list_lock);
return ret;
}
EXPORT_SYMBOL_GPL(nf_conncount_gc_list);
static void __tree_nodes_free(struct rcu_head *h)
{
struct nf_conncount_rb *rbconn;
rbconn = container_of(h, struct nf_conncount_rb, rcu_head);
kmem_cache_free(conncount_rb_cachep, rbconn);
}
static void tree_nodes_free(struct rb_root *root,
struct nf_conncount_rb *gc_nodes[],
unsigned int gc_count)
{
struct nf_conncount_rb *rbconn;
while (gc_count) {
rbconn = gc_nodes[--gc_count];
spin_lock(&rbconn->list.list_lock);
rb_erase(&rbconn->node, root);
call_rcu(&rbconn->rcu_head, __tree_nodes_free);
spin_unlock(&rbconn->list.list_lock);
}
}
static void schedule_gc_worker(struct nf_conncount_data *data, int tree)
{
set_bit(tree, data->pending_trees);
schedule_work(&data->gc_work);
}
static unsigned int
insert_tree(struct net *net,
struct nf_conncount_data *data,
struct rb_root *root,
unsigned int hash,
const u32 *key,
u8 keylen,
const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone)
{
struct nf_conncount_rb *gc_nodes[CONNCOUNT_GC_MAX_NODES];
struct rb_node **rbnode, *parent;
struct nf_conncount_rb *rbconn;
struct nf_conncount_tuple *conn;
unsigned int count = 0, gc_count = 0;
bool do_gc = true;
spin_lock_bh(&nf_conncount_locks[hash]);
restart:
parent = NULL;
rbnode = &(root->rb_node);
while (*rbnode) {
int diff;
rbconn = rb_entry(*rbnode, struct nf_conncount_rb, node);
parent = *rbnode;
diff = key_diff(key, rbconn->key, keylen);
if (diff < 0) {
rbnode = &((*rbnode)->rb_left);
} else if (diff > 0) {
rbnode = &((*rbnode)->rb_right);
} else {
int ret;
ret = nf_conncount_add(net, &rbconn->list, tuple, zone);
if (ret)
count = 0; /* hotdrop */
else
count = rbconn->list.count;
tree_nodes_free(root, gc_nodes, gc_count);
goto out_unlock;
}
if (gc_count >= ARRAY_SIZE(gc_nodes))
continue;
if (do_gc && nf_conncount_gc_list(net, &rbconn->list))
gc_nodes[gc_count++] = rbconn;
}
if (gc_count) {
tree_nodes_free(root, gc_nodes, gc_count);
schedule_gc_worker(data, hash);
gc_count = 0;
do_gc = false;
goto restart;
}
/* expected case: match, insert new node */
rbconn = kmem_cache_alloc(conncount_rb_cachep, GFP_ATOMIC);
if (rbconn == NULL)
goto out_unlock;
conn = kmem_cache_alloc(conncount_conn_cachep, GFP_ATOMIC);
if (conn == NULL) {
kmem_cache_free(conncount_rb_cachep, rbconn);
goto out_unlock;
}
conn->tuple = *tuple;
conn->zone = *zone;
memcpy(rbconn->key, key, sizeof(u32) * keylen);
nf_conncount_list_init(&rbconn->list);
list_add(&conn->node, &rbconn->list.head);
count = 1;
rbconn->list.count = count;
rb_link_node_rcu(&rbconn->node, parent, rbnode);
rb_insert_color(&rbconn->node, root);
out_unlock:
spin_unlock_bh(&nf_conncount_locks[hash]);
return count;
}
static unsigned int
count_tree(struct net *net,
struct nf_conncount_data *data,
const u32 *key,
const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone)
{
struct rb_root *root;
struct rb_node *parent;
struct nf_conncount_rb *rbconn;
unsigned int hash;
u8 keylen = data->keylen;
hash = jhash2(key, data->keylen, conncount_rnd) % CONNCOUNT_SLOTS;
root = &data->root[hash];
parent = rcu_dereference_raw(root->rb_node);
while (parent) {
int diff;
rbconn = rb_entry(parent, struct nf_conncount_rb, node);
diff = key_diff(key, rbconn->key, keylen);
if (diff < 0) {
parent = rcu_dereference_raw(parent->rb_left);
} else if (diff > 0) {
parent = rcu_dereference_raw(parent->rb_right);
} else {
int ret;
if (!tuple) {
nf_conncount_gc_list(net, &rbconn->list);
return rbconn->list.count;
}
spin_lock_bh(&rbconn->list.list_lock);
/* Node might be about to be free'd.
* We need to defer to insert_tree() in this case.
*/
if (rbconn->list.count == 0) {
spin_unlock_bh(&rbconn->list.list_lock);
break;
}
/* same source network -> be counted! */
ret = __nf_conncount_add(net, &rbconn->list, tuple, zone);
spin_unlock_bh(&rbconn->list.list_lock);
if (ret)
return 0; /* hotdrop */
else
return rbconn->list.count;
}
}
if (!tuple)
return 0;
return insert_tree(net, data, root, hash, key, keylen, tuple, zone);
}
static void tree_gc_worker(struct work_struct *work)
{
struct nf_conncount_data *data = container_of(work, struct nf_conncount_data, gc_work);
struct nf_conncount_rb *gc_nodes[CONNCOUNT_GC_MAX_NODES], *rbconn;
struct rb_root *root;
struct rb_node *node;
unsigned int tree, next_tree, gc_count = 0;
tree = data->gc_tree % CONNCOUNT_SLOTS;
root = &data->root[tree];
rcu_read_lock();
for (node = rb_first(root); node != NULL; node = rb_next(node)) {
rbconn = rb_entry(node, struct nf_conncount_rb, node);
if (nf_conncount_gc_list(data->net, &rbconn->list))
gc_count++;
}
rcu_read_unlock();
spin_lock_bh(&nf_conncount_locks[tree]);
if (gc_count < ARRAY_SIZE(gc_nodes))
goto next; /* do not bother */
gc_count = 0;
node = rb_first(root);
while (node != NULL) {
rbconn = rb_entry(node, struct nf_conncount_rb, node);
node = rb_next(node);
if (rbconn->list.count > 0)
continue;
gc_nodes[gc_count++] = rbconn;
if (gc_count >= ARRAY_SIZE(gc_nodes)) {
tree_nodes_free(root, gc_nodes, gc_count);
gc_count = 0;
}
}
tree_nodes_free(root, gc_nodes, gc_count);
next:
clear_bit(tree, data->pending_trees);
next_tree = (tree + 1) % CONNCOUNT_SLOTS;
next_tree = find_next_bit(data->pending_trees, next_tree, CONNCOUNT_SLOTS);
if (next_tree < CONNCOUNT_SLOTS) {
data->gc_tree = next_tree;
schedule_work(work);
}
spin_unlock_bh(&nf_conncount_locks[tree]);
}
/* Count and return number of conntrack entries in 'net' with particular 'key'.
* If 'tuple' is not null, insert it into the accounting data structure.
* Call with RCU read lock.
*/
unsigned int nf_conncount_count(struct net *net,
struct nf_conncount_data *data,
const u32 *key,
const struct nf_conntrack_tuple *tuple,
const struct nf_conntrack_zone *zone)
{
return count_tree(net, data, key, tuple, zone);
}
EXPORT_SYMBOL_GPL(nf_conncount_count);
struct nf_conncount_data *nf_conncount_init(struct net *net, unsigned int family,
unsigned int keylen)
{
struct nf_conncount_data *data;
int ret, i;
if (keylen % sizeof(u32) ||
keylen / sizeof(u32) > MAX_KEYLEN ||
keylen == 0)
return ERR_PTR(-EINVAL);
net_get_random_once(&conncount_rnd, sizeof(conncount_rnd));
data = kmalloc(sizeof(*data), GFP_KERNEL);
if (!data)
return ERR_PTR(-ENOMEM);
ret = nf_ct_netns_get(net, family);
if (ret < 0) {
kfree(data);
return ERR_PTR(ret);
}
for (i = 0; i < ARRAY_SIZE(data->root); ++i)
data->root[i] = RB_ROOT;
data->keylen = keylen / sizeof(u32);
data->net = net;
INIT_WORK(&data->gc_work, tree_gc_worker);
return data;
}
EXPORT_SYMBOL_GPL(nf_conncount_init);
void nf_conncount_cache_free(struct nf_conncount_list *list)
{
struct nf_conncount_tuple *conn, *conn_n;
list_for_each_entry_safe(conn, conn_n, &list->head, node)
kmem_cache_free(conncount_conn_cachep, conn);
}
EXPORT_SYMBOL_GPL(nf_conncount_cache_free);
static void destroy_tree(struct rb_root *r)
{
struct nf_conncount_rb *rbconn;
struct rb_node *node;
while ((node = rb_first(r)) != NULL) {
rbconn = rb_entry(node, struct nf_conncount_rb, node);
rb_erase(node, r);
nf_conncount_cache_free(&rbconn->list);
kmem_cache_free(conncount_rb_cachep, rbconn);
}
}
void nf_conncount_destroy(struct net *net, unsigned int family,
struct nf_conncount_data *data)
{
unsigned int i;
cancel_work_sync(&data->gc_work);
nf_ct_netns_put(net, family);
for (i = 0; i < ARRAY_SIZE(data->root); ++i)
destroy_tree(&data->root[i]);
kfree(data);
}
EXPORT_SYMBOL_GPL(nf_conncount_destroy);
static int __init nf_conncount_modinit(void)
{
int i;
for (i = 0; i < CONNCOUNT_SLOTS; ++i)
spin_lock_init(&nf_conncount_locks[i]);
conncount_conn_cachep = kmem_cache_create("nf_conncount_tuple",
sizeof(struct nf_conncount_tuple),
0, 0, NULL);
if (!conncount_conn_cachep)
return -ENOMEM;
conncount_rb_cachep = kmem_cache_create("nf_conncount_rb",
sizeof(struct nf_conncount_rb),
0, 0, NULL);
if (!conncount_rb_cachep) {
kmem_cache_destroy(conncount_conn_cachep);
return -ENOMEM;
}
return 0;
}
static void __exit nf_conncount_modexit(void)
{
kmem_cache_destroy(conncount_conn_cachep);
kmem_cache_destroy(conncount_rb_cachep);
}
module_init(nf_conncount_modinit);
module_exit(nf_conncount_modexit);
MODULE_AUTHOR("Jan Engelhardt <jengelh@medozas.de>");
MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
MODULE_DESCRIPTION("netfilter: count number of connections matching a key");
MODULE_LICENSE("GPL");
|