aboutsummaryrefslogtreecommitdiff
path: root/kernel/bpf/net_namespace.c
blob: 542f275bf2523b77e86141ae3729ef67f0b5d6cb (plain)
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
// SPDX-License-Identifier: GPL-2.0

#include <linux/bpf.h>
#include <linux/filter.h>
#include <net/net_namespace.h>

/*
 * Functions to manage BPF programs attached to netns
 */

struct bpf_netns_link {
	struct bpf_link	link;
	enum bpf_attach_type type;
	enum netns_bpf_attach_type netns_type;

	/* We don't hold a ref to net in order to auto-detach the link
	 * when netns is going away. Instead we rely on pernet
	 * pre_exit callback to clear this pointer. Must be accessed
	 * with netns_bpf_mutex held.
	 */
	struct net *net;
	struct list_head node; /* node in list of links attached to net */
};

/* Protects updates to netns_bpf */
DEFINE_MUTEX(netns_bpf_mutex);

static void netns_bpf_attach_type_unneed(enum netns_bpf_attach_type type)
{
	switch (type) {
#ifdef CONFIG_INET
	case NETNS_BPF_SK_LOOKUP:
		static_branch_dec(&bpf_sk_lookup_enabled);
		break;
#endif
	default:
		break;
	}
}

static void netns_bpf_attach_type_need(enum netns_bpf_attach_type type)
{
	switch (type) {
#ifdef CONFIG_INET
	case NETNS_BPF_SK_LOOKUP:
		static_branch_inc(&bpf_sk_lookup_enabled);
		break;
#endif
	default:
		break;
	}
}

/* Must be called with netns_bpf_mutex held. */
static void netns_bpf_run_array_detach(struct net *net,
				       enum netns_bpf_attach_type type)
{
	struct bpf_prog_array *run_array;

	run_array = rcu_replace_pointer(net->bpf.run_array[type], NULL,
					lockdep_is_held(&netns_bpf_mutex));
	bpf_prog_array_free(run_array);
}

static int link_index(struct net *net, enum netns_bpf_attach_type type,
		      struct bpf_netns_link *link)
{
	struct bpf_netns_link *pos;
	int i = 0;

	list_for_each_entry(pos, &net->bpf.links[type], node) {
		if (pos == link)
			return i;
		i++;
	}
	return -ENOENT;
}

static int link_count(struct net *net, enum netns_bpf_attach_type type)
{
	struct list_head *pos;
	int i = 0;

	list_for_each(pos, &net->bpf.links[type])
		i++;
	return i;
}

static void fill_prog_array(struct net *net, enum netns_bpf_attach_type type,
			    struct bpf_prog_array *prog_array)
{
	struct bpf_netns_link *pos;
	unsigned int i = 0;

	list_for_each_entry(pos, &net->bpf.links[type], node) {
		prog_array->items[i].prog = pos->link.prog;
		i++;
	}
}

static void bpf_netns_link_release(struct bpf_link *link)
{
	struct bpf_netns_link *net_link =
		container_of(link, struct bpf_netns_link, link);
	enum netns_bpf_attach_type type = net_link->netns_type;
	struct bpf_prog_array *old_array, *new_array;
	struct net *net;
	int cnt, idx;

	mutex_lock(&netns_bpf_mutex);

	/* We can race with cleanup_net, but if we see a non-NULL
	 * struct net pointer, pre_exit has not run yet and wait for
	 * netns_bpf_mutex.
	 */
	net = net_link->net;
	if (!net)
		goto out_unlock;

	/* Mark attach point as unused */
	netns_bpf_attach_type_unneed(type);

	/* Remember link position in case of safe delete */
	idx = link_index(net, type, net_link);
	list_del(&net_link->node);

	cnt = link_count(net, type);
	if (!cnt) {
		netns_bpf_run_array_detach(net, type);
		goto out_unlock;
	}

	old_array = rcu_dereference_protected(net->bpf.run_array[type],
					      lockdep_is_held(&netns_bpf_mutex));
	new_array = bpf_prog_array_alloc(cnt, GFP_KERNEL);
	if (!new_array) {
		WARN_ON(bpf_prog_array_delete_safe_at(old_array, idx));
		goto out_unlock;
	}
	fill_prog_array(net, type, new_array);
	rcu_assign_pointer(net->bpf.run_array[type], new_array);
	bpf_prog_array_free(old_array);

out_unlock:
	net_link->net = NULL;
	mutex_unlock(&netns_bpf_mutex);
}

static int bpf_netns_link_detach(struct bpf_link *link)
{
	bpf_netns_link_release(link);
	return 0;
}

static void bpf_netns_link_dealloc(struct bpf_link *link)
{
	struct bpf_netns_link *net_link =
		container_of(link, struct bpf_netns_link, link);

	kfree(net_link);
}

static int bpf_netns_link_update_prog(struct bpf_link *link,
				      struct bpf_prog *new_prog,
				      struct bpf_prog *old_prog)
{
	struct bpf_netns_link *net_link =
		container_of(link, struct bpf_netns_link, link);
	enum netns_bpf_attach_type type = net_link->netns_type;
	struct bpf_prog_array *run_array;
	struct net *net;
	int idx, ret;

	if (old_prog && old_prog != link->prog)
		return -EPERM;
	if (new_prog->type != link->prog->type)
		return -EINVAL;

	mutex_lock(&netns_bpf_mutex);

	net = net_link->net;
	if (!net || !check_net(net)) {
		/* Link auto-detached or netns dying */
		ret = -ENOLINK;
		goto out_unlock;
	}

	run_array = rcu_dereference_protected(net->bpf.run_array[type],
					      lockdep_is_held(&netns_bpf_mutex));
	idx = link_index(net, type, net_link);
	ret = bpf_prog_array_update_at(run_array, idx, new_prog);
	if (ret)
		goto out_unlock;

	old_prog = xchg(&link->prog, new_prog);
	bpf_prog_put(old_prog);

out_unlock:
	mutex_unlock(&netns_bpf_mutex);
	return ret;
}

static int bpf_netns_link_fill_info(const struct bpf_link *link,
				    struct bpf_link_info *info)
{
	const struct bpf_netns_link *net_link =
		container_of(link, struct bpf_netns_link, link);
	unsigned int inum = 0;
	struct net *net;

	mutex_lock(&netns_bpf_mutex);
	net = net_link->net;
	if (net && check_net(net))
		inum = net->ns.inum;
	mutex_unlock(&netns_bpf_mutex);

	info->netns.netns_ino = inum;
	info->netns.attach_type = net_link->type;
	return 0;
}

static void bpf_netns_link_show_fdinfo(const struct bpf_link *link,
				       struct seq_file *seq)
{
	struct bpf_link_info info = {};

	bpf_netns_link_fill_info(link, &info);
	seq_printf(seq,
		   "netns_ino:\t%u\n"
		   "attach_type:\t%u\n",
		   info.netns.netns_ino,
		   info.netns.attach_type);
}

static const struct bpf_link_ops bpf_netns_link_ops = {
	.release = bpf_netns_link_release,
	.dealloc = bpf_netns_link_dealloc,
	.detach = bpf_netns_link_detach,
	.update_prog = bpf_netns_link_update_prog,
	.fill_link_info = bpf_netns_link_fill_info,
	.show_fdinfo = bpf_netns_link_show_fdinfo,
};

/* Must be called with netns_bpf_mutex held. */
static int __netns_bpf_prog_query(const union bpf_attr *attr,
				  union bpf_attr __user *uattr,
				  struct net *net,
				  enum netns_bpf_attach_type type)
{
	__u32 __user *prog_ids = u64_to_user_ptr(attr->query.prog_ids);
	struct bpf_prog_array *run_array;
	u32 prog_cnt = 0, flags = 0;

	run_array = rcu_dereference_protected(net->bpf.run_array[type],
					      lockdep_is_held(&netns_bpf_mutex));
	if (run_array)
		prog_cnt = bpf_prog_array_length(run_array);

	if (copy_to_user(&uattr->query.attach_flags, &flags, sizeof(flags)))
		return -EFAULT;
	if (copy_to_user(&uattr->query.prog_cnt, &prog_cnt, sizeof(prog_cnt)))
		return -EFAULT;
	if (!attr->query.prog_cnt || !prog_ids || !prog_cnt)
		return 0;

	return bpf_prog_array_copy_to_user(run_array, prog_ids,
					   attr->query.prog_cnt);
}

int netns_bpf_prog_query(const union bpf_attr *attr,
			 union bpf_attr __user *uattr)
{
	enum netns_bpf_attach_type type;
	struct net *net;
	int ret;

	if (attr->query.query_flags)
		return -EINVAL;

	type = to_netns_bpf_attach_type(attr->query.attach_type);
	if (type < 0)
		return -EINVAL;

	net = get_net_ns_by_fd(attr->query.target_fd);
	if (IS_ERR(net))
		return PTR_ERR(net);

	mutex_lock(&netns_bpf_mutex);
	ret = __netns_bpf_prog_query(attr, uattr, net, type);
	mutex_unlock(&netns_bpf_mutex);

	put_net(net);
	return ret;
}

int netns_bpf_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
{
	struct bpf_prog_array *run_array;
	enum netns_bpf_attach_type type;
	struct bpf_prog *attached;
	struct net *net;
	int ret;

	if (attr->target_fd || attr->attach_flags || attr->replace_bpf_fd)
		return -EINVAL;

	type = to_netns_bpf_attach_type(attr->attach_type);
	if (type < 0)
		return -EINVAL;

	net = current->nsproxy->net_ns;
	mutex_lock(&netns_bpf_mutex);

	/* Attaching prog directly is not compatible with links */
	if (!list_empty(&net->bpf.links[type])) {
		ret = -EEXIST;
		goto out_unlock;
	}

	switch (type) {
	case NETNS_BPF_FLOW_DISSECTOR:
		ret = flow_dissector_bpf_prog_attach_check(net, prog);
		break;
	default:
		ret = -EINVAL;
		break;
	}
	if (ret)
		goto out_unlock;

	attached = net->bpf.progs[type];
	if (attached == prog) {
		/* The same program cannot be attached twice */
		ret = -EINVAL;
		goto out_unlock;
	}

	run_array = rcu_dereference_protected(net->bpf.run_array[type],
					      lockdep_is_held(&netns_bpf_mutex));
	if (run_array) {
		WRITE_ONCE(run_array->items[0].prog, prog);
	} else {
		run_array = bpf_prog_array_alloc(1, GFP_KERNEL);
		if (!run_array) {
			ret = -ENOMEM;
			goto out_unlock;
		}
		run_array->items[0].prog = prog;
		rcu_assign_pointer(net->bpf.run_array[type], run_array);
	}

	net->bpf.progs[type] = prog;
	if (attached)
		bpf_prog_put(attached);

out_unlock:
	mutex_unlock(&netns_bpf_mutex);

	return ret;
}

/* Must be called with netns_bpf_mutex held. */
static int __netns_bpf_prog_detach(struct net *net,
				   enum netns_bpf_attach_type type,
				   struct bpf_prog *old)
{
	struct bpf_prog *attached;

	/* Progs attached via links cannot be detached */
	if (!list_empty(&net->bpf.links[type]))
		return -EINVAL;

	attached = net->bpf.progs[type];
	if (!attached || attached != old)
		return -ENOENT;
	netns_bpf_run_array_detach(net, type);
	net->bpf.progs[type] = NULL;
	bpf_prog_put(attached);
	return 0;
}

int netns_bpf_prog_detach(const union bpf_attr *attr, enum bpf_prog_type ptype)
{
	enum netns_bpf_attach_type type;
	struct bpf_prog *prog;
	int ret;

	if (attr->target_fd)
		return -EINVAL;

	type = to_netns_bpf_attach_type(attr->attach_type);
	if (type < 0)
		return -EINVAL;

	prog = bpf_prog_get_type(attr->attach_bpf_fd, ptype);
	if (IS_ERR(prog))
		return PTR_ERR(prog);

	mutex_lock(&netns_bpf_mutex);
	ret = __netns_bpf_prog_detach(current->nsproxy->net_ns, type, prog);
	mutex_unlock(&netns_bpf_mutex);

	bpf_prog_put(prog);

	return ret;
}

static int netns_bpf_max_progs(enum netns_bpf_attach_type type)
{
	switch (type) {
	case NETNS_BPF_FLOW_DISSECTOR:
		return 1;
	case NETNS_BPF_SK_LOOKUP:
		return 64;
	default:
		return 0;
	}
}

static int netns_bpf_link_attach(struct net *net, struct bpf_link *link,
				 enum netns_bpf_attach_type type)
{
	struct bpf_netns_link *net_link =
		container_of(link, struct bpf_netns_link, link);
	struct bpf_prog_array *run_array;
	int cnt, err;

	mutex_lock(&netns_bpf_mutex);

	cnt = link_count(net, type);
	if (cnt >= netns_bpf_max_progs(type)) {
		err = -E2BIG;
		goto out_unlock;
	}
	/* Links are not compatible with attaching prog directly */
	if (net->bpf.progs[type]) {
		err = -EEXIST;
		goto out_unlock;
	}

	switch (type) {
	case NETNS_BPF_FLOW_DISSECTOR:
		err = flow_dissector_bpf_prog_attach_check(net, link->prog);
		break;
	case NETNS_BPF_SK_LOOKUP:
		err = 0; /* nothing to check */
		break;
	default:
		err = -EINVAL;
		break;
	}
	if (err)
		goto out_unlock;

	run_array = bpf_prog_array_alloc(cnt + 1, GFP_KERNEL);
	if (!run_array) {
		err = -ENOMEM;
		goto out_unlock;
	}

	list_add_tail(&net_link->node, &net->bpf.links[type]);

	fill_prog_array(net, type, run_array);
	run_array = rcu_replace_pointer(net->bpf.run_array[type], run_array,
					lockdep_is_held(&netns_bpf_mutex));
	bpf_prog_array_free(run_array);

	/* Mark attach point as used */
	netns_bpf_attach_type_need(type);

out_unlock:
	mutex_unlock(&netns_bpf_mutex);
	return err;
}

int netns_bpf_link_create(const union bpf_attr *attr, struct bpf_prog *prog)
{
	enum netns_bpf_attach_type netns_type;
	struct bpf_link_primer link_primer;
	struct bpf_netns_link *net_link;
	enum bpf_attach_type type;
	struct net *net;
	int err;

	if (attr->link_create.flags)
		return -EINVAL;

	type = attr->link_create.attach_type;
	netns_type = to_netns_bpf_attach_type(type);
	if (netns_type < 0)
		return -EINVAL;

	net = get_net_ns_by_fd(attr->link_create.target_fd);
	if (IS_ERR(net))
		return PTR_ERR(net);

	net_link = kzalloc(sizeof(*net_link), GFP_USER);
	if (!net_link) {
		err = -ENOMEM;
		goto out_put_net;
	}
	bpf_link_init(&net_link->link, BPF_LINK_TYPE_NETNS,
		      &bpf_netns_link_ops, prog);
	net_link->net = net;
	net_link->type = type;
	net_link->netns_type = netns_type;

	err = bpf_link_prime(&net_link->link, &link_primer);
	if (err) {
		kfree(net_link);
		goto out_put_net;
	}

	err = netns_bpf_link_attach(net, &net_link->link, netns_type);
	if (err) {
		bpf_link_cleanup(&link_primer);
		goto out_put_net;
	}

	put_net(net);
	return bpf_link_settle(&link_primer);

out_put_net:
	put_net(net);
	return err;
}

static int __net_init netns_bpf_pernet_init(struct net *net)
{
	int type;

	for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++)
		INIT_LIST_HEAD(&net->bpf.links[type]);

	return 0;
}

static void __net_exit netns_bpf_pernet_pre_exit(struct net *net)
{
	enum netns_bpf_attach_type type;
	struct bpf_netns_link *net_link;

	mutex_lock(&netns_bpf_mutex);
	for (type = 0; type < MAX_NETNS_BPF_ATTACH_TYPE; type++) {
		netns_bpf_run_array_detach(net, type);
		list_for_each_entry(net_link, &net->bpf.links[type], node) {
			net_link->net = NULL; /* auto-detach link */
			netns_bpf_attach_type_unneed(type);
		}
		if (net->bpf.progs[type])
			bpf_prog_put(net->bpf.progs[type]);
	}
	mutex_unlock(&netns_bpf_mutex);
}

static struct pernet_operations netns_bpf_pernet_ops __net_initdata = {
	.init = netns_bpf_pernet_init,
	.pre_exit = netns_bpf_pernet_pre_exit,
};

static int __init netns_bpf_init(void)
{
	return register_pernet_subsys(&netns_bpf_pernet_ops);
}

subsys_initcall(netns_bpf_init);