xref: /linux/net/core/lwt_bpf.c (revision b58b13f156c00c2457035b7071eaaac105fe6836)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (c) 2016 Thomas Graf <tgraf@tgraf.ch>
3  */
4 
5 #include <linux/filter.h>
6 #include <linux/kernel.h>
7 #include <linux/module.h>
8 #include <linux/skbuff.h>
9 #include <linux/types.h>
10 #include <linux/bpf.h>
11 #include <net/lwtunnel.h>
12 #include <net/gre.h>
13 #include <net/ip6_route.h>
14 #include <net/ipv6_stubs.h>
15 
16 struct bpf_lwt_prog {
17 	struct bpf_prog *prog;
18 	char *name;
19 };
20 
21 struct bpf_lwt {
22 	struct bpf_lwt_prog in;
23 	struct bpf_lwt_prog out;
24 	struct bpf_lwt_prog xmit;
25 	int family;
26 };
27 
28 #define MAX_PROG_NAME 256
29 
30 static inline struct bpf_lwt *bpf_lwt_lwtunnel(struct lwtunnel_state *lwt)
31 {
32 	return (struct bpf_lwt *)lwt->data;
33 }
34 
35 #define NO_REDIRECT false
36 #define CAN_REDIRECT true
37 
38 static int run_lwt_bpf(struct sk_buff *skb, struct bpf_lwt_prog *lwt,
39 		       struct dst_entry *dst, bool can_redirect)
40 {
41 	int ret;
42 
43 	/* Migration disable and BH disable are needed to protect per-cpu
44 	 * redirect_info between BPF prog and skb_do_redirect().
45 	 */
46 	migrate_disable();
47 	local_bh_disable();
48 	bpf_compute_data_pointers(skb);
49 	ret = bpf_prog_run_save_cb(lwt->prog, skb);
50 
51 	switch (ret) {
52 	case BPF_OK:
53 	case BPF_LWT_REROUTE:
54 		break;
55 
56 	case BPF_REDIRECT:
57 		if (unlikely(!can_redirect)) {
58 			pr_warn_once("Illegal redirect return code in prog %s\n",
59 				     lwt->name ? : "<unknown>");
60 			ret = BPF_OK;
61 		} else {
62 			skb_reset_mac_header(skb);
63 			skb_do_redirect(skb);
64 			ret = BPF_REDIRECT;
65 		}
66 		break;
67 
68 	case BPF_DROP:
69 		kfree_skb(skb);
70 		ret = -EPERM;
71 		break;
72 
73 	default:
74 		pr_warn_once("bpf-lwt: Illegal return value %u, expect packet loss\n", ret);
75 		kfree_skb(skb);
76 		ret = -EINVAL;
77 		break;
78 	}
79 
80 	local_bh_enable();
81 	migrate_enable();
82 
83 	return ret;
84 }
85 
86 static int bpf_lwt_input_reroute(struct sk_buff *skb)
87 {
88 	int err = -EINVAL;
89 
90 	if (skb->protocol == htons(ETH_P_IP)) {
91 		struct net_device *dev = skb_dst(skb)->dev;
92 		struct iphdr *iph = ip_hdr(skb);
93 
94 		dev_hold(dev);
95 		skb_dst_drop(skb);
96 		err = ip_route_input_noref(skb, iph->daddr, iph->saddr,
97 					   iph->tos, dev);
98 		dev_put(dev);
99 	} else if (skb->protocol == htons(ETH_P_IPV6)) {
100 		skb_dst_drop(skb);
101 		err = ipv6_stub->ipv6_route_input(skb);
102 	} else {
103 		err = -EAFNOSUPPORT;
104 	}
105 
106 	if (err)
107 		goto err;
108 	return dst_input(skb);
109 
110 err:
111 	kfree_skb(skb);
112 	return err;
113 }
114 
115 static int bpf_input(struct sk_buff *skb)
116 {
117 	struct dst_entry *dst = skb_dst(skb);
118 	struct bpf_lwt *bpf;
119 	int ret;
120 
121 	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
122 	if (bpf->in.prog) {
123 		ret = run_lwt_bpf(skb, &bpf->in, dst, NO_REDIRECT);
124 		if (ret < 0)
125 			return ret;
126 		if (ret == BPF_LWT_REROUTE)
127 			return bpf_lwt_input_reroute(skb);
128 	}
129 
130 	if (unlikely(!dst->lwtstate->orig_input)) {
131 		kfree_skb(skb);
132 		return -EINVAL;
133 	}
134 
135 	return dst->lwtstate->orig_input(skb);
136 }
137 
138 static int bpf_output(struct net *net, struct sock *sk, struct sk_buff *skb)
139 {
140 	struct dst_entry *dst = skb_dst(skb);
141 	struct bpf_lwt *bpf;
142 	int ret;
143 
144 	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
145 	if (bpf->out.prog) {
146 		ret = run_lwt_bpf(skb, &bpf->out, dst, NO_REDIRECT);
147 		if (ret < 0)
148 			return ret;
149 	}
150 
151 	if (unlikely(!dst->lwtstate->orig_output)) {
152 		pr_warn_once("orig_output not set on dst for prog %s\n",
153 			     bpf->out.name);
154 		kfree_skb(skb);
155 		return -EINVAL;
156 	}
157 
158 	return dst->lwtstate->orig_output(net, sk, skb);
159 }
160 
161 static int xmit_check_hhlen(struct sk_buff *skb, int hh_len)
162 {
163 	if (skb_headroom(skb) < hh_len) {
164 		int nhead = HH_DATA_ALIGN(hh_len - skb_headroom(skb));
165 
166 		if (pskb_expand_head(skb, nhead, 0, GFP_ATOMIC))
167 			return -ENOMEM;
168 	}
169 
170 	return 0;
171 }
172 
173 static int bpf_lwt_xmit_reroute(struct sk_buff *skb)
174 {
175 	struct net_device *l3mdev = l3mdev_master_dev_rcu(skb_dst(skb)->dev);
176 	int oif = l3mdev ? l3mdev->ifindex : 0;
177 	struct dst_entry *dst = NULL;
178 	int err = -EAFNOSUPPORT;
179 	struct sock *sk;
180 	struct net *net;
181 	bool ipv4;
182 
183 	if (skb->protocol == htons(ETH_P_IP))
184 		ipv4 = true;
185 	else if (skb->protocol == htons(ETH_P_IPV6))
186 		ipv4 = false;
187 	else
188 		goto err;
189 
190 	sk = sk_to_full_sk(skb->sk);
191 	if (sk) {
192 		if (sk->sk_bound_dev_if)
193 			oif = sk->sk_bound_dev_if;
194 		net = sock_net(sk);
195 	} else {
196 		net = dev_net(skb_dst(skb)->dev);
197 	}
198 
199 	if (ipv4) {
200 		struct iphdr *iph = ip_hdr(skb);
201 		struct flowi4 fl4 = {};
202 		struct rtable *rt;
203 
204 		fl4.flowi4_oif = oif;
205 		fl4.flowi4_mark = skb->mark;
206 		fl4.flowi4_uid = sock_net_uid(net, sk);
207 		fl4.flowi4_tos = RT_TOS(iph->tos);
208 		fl4.flowi4_flags = FLOWI_FLAG_ANYSRC;
209 		fl4.flowi4_proto = iph->protocol;
210 		fl4.daddr = iph->daddr;
211 		fl4.saddr = iph->saddr;
212 
213 		rt = ip_route_output_key(net, &fl4);
214 		if (IS_ERR(rt)) {
215 			err = PTR_ERR(rt);
216 			goto err;
217 		}
218 		dst = &rt->dst;
219 	} else {
220 		struct ipv6hdr *iph6 = ipv6_hdr(skb);
221 		struct flowi6 fl6 = {};
222 
223 		fl6.flowi6_oif = oif;
224 		fl6.flowi6_mark = skb->mark;
225 		fl6.flowi6_uid = sock_net_uid(net, sk);
226 		fl6.flowlabel = ip6_flowinfo(iph6);
227 		fl6.flowi6_proto = iph6->nexthdr;
228 		fl6.daddr = iph6->daddr;
229 		fl6.saddr = iph6->saddr;
230 
231 		dst = ipv6_stub->ipv6_dst_lookup_flow(net, skb->sk, &fl6, NULL);
232 		if (IS_ERR(dst)) {
233 			err = PTR_ERR(dst);
234 			goto err;
235 		}
236 	}
237 	if (unlikely(dst->error)) {
238 		err = dst->error;
239 		dst_release(dst);
240 		goto err;
241 	}
242 
243 	/* Although skb header was reserved in bpf_lwt_push_ip_encap(), it
244 	 * was done for the previous dst, so we are doing it here again, in
245 	 * case the new dst needs much more space. The call below is a noop
246 	 * if there is enough header space in skb.
247 	 */
248 	err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
249 	if (unlikely(err))
250 		goto err;
251 
252 	skb_dst_drop(skb);
253 	skb_dst_set(skb, dst);
254 
255 	err = dst_output(dev_net(skb_dst(skb)->dev), skb->sk, skb);
256 	if (unlikely(err))
257 		return net_xmit_errno(err);
258 
259 	/* ip[6]_finish_output2 understand LWTUNNEL_XMIT_DONE */
260 	return LWTUNNEL_XMIT_DONE;
261 
262 err:
263 	kfree_skb(skb);
264 	return err;
265 }
266 
267 static int bpf_xmit(struct sk_buff *skb)
268 {
269 	struct dst_entry *dst = skb_dst(skb);
270 	struct bpf_lwt *bpf;
271 
272 	bpf = bpf_lwt_lwtunnel(dst->lwtstate);
273 	if (bpf->xmit.prog) {
274 		int hh_len = dst->dev->hard_header_len;
275 		__be16 proto = skb->protocol;
276 		int ret;
277 
278 		ret = run_lwt_bpf(skb, &bpf->xmit, dst, CAN_REDIRECT);
279 		switch (ret) {
280 		case BPF_OK:
281 			/* If the header changed, e.g. via bpf_lwt_push_encap,
282 			 * BPF_LWT_REROUTE below should have been used if the
283 			 * protocol was also changed.
284 			 */
285 			if (skb->protocol != proto) {
286 				kfree_skb(skb);
287 				return -EINVAL;
288 			}
289 			/* If the header was expanded, headroom might be too
290 			 * small for L2 header to come, expand as needed.
291 			 */
292 			ret = xmit_check_hhlen(skb, hh_len);
293 			if (unlikely(ret))
294 				return ret;
295 
296 			return LWTUNNEL_XMIT_CONTINUE;
297 		case BPF_REDIRECT:
298 			return LWTUNNEL_XMIT_DONE;
299 		case BPF_LWT_REROUTE:
300 			return bpf_lwt_xmit_reroute(skb);
301 		default:
302 			return ret;
303 		}
304 	}
305 
306 	return LWTUNNEL_XMIT_CONTINUE;
307 }
308 
309 static void bpf_lwt_prog_destroy(struct bpf_lwt_prog *prog)
310 {
311 	if (prog->prog)
312 		bpf_prog_put(prog->prog);
313 
314 	kfree(prog->name);
315 }
316 
317 static void bpf_destroy_state(struct lwtunnel_state *lwt)
318 {
319 	struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);
320 
321 	bpf_lwt_prog_destroy(&bpf->in);
322 	bpf_lwt_prog_destroy(&bpf->out);
323 	bpf_lwt_prog_destroy(&bpf->xmit);
324 }
325 
326 static const struct nla_policy bpf_prog_policy[LWT_BPF_PROG_MAX + 1] = {
327 	[LWT_BPF_PROG_FD]   = { .type = NLA_U32, },
328 	[LWT_BPF_PROG_NAME] = { .type = NLA_NUL_STRING,
329 				.len = MAX_PROG_NAME },
330 };
331 
332 static int bpf_parse_prog(struct nlattr *attr, struct bpf_lwt_prog *prog,
333 			  enum bpf_prog_type type)
334 {
335 	struct nlattr *tb[LWT_BPF_PROG_MAX + 1];
336 	struct bpf_prog *p;
337 	int ret;
338 	u32 fd;
339 
340 	ret = nla_parse_nested_deprecated(tb, LWT_BPF_PROG_MAX, attr,
341 					  bpf_prog_policy, NULL);
342 	if (ret < 0)
343 		return ret;
344 
345 	if (!tb[LWT_BPF_PROG_FD] || !tb[LWT_BPF_PROG_NAME])
346 		return -EINVAL;
347 
348 	prog->name = nla_memdup(tb[LWT_BPF_PROG_NAME], GFP_ATOMIC);
349 	if (!prog->name)
350 		return -ENOMEM;
351 
352 	fd = nla_get_u32(tb[LWT_BPF_PROG_FD]);
353 	p = bpf_prog_get_type(fd, type);
354 	if (IS_ERR(p))
355 		return PTR_ERR(p);
356 
357 	prog->prog = p;
358 
359 	return 0;
360 }
361 
362 static const struct nla_policy bpf_nl_policy[LWT_BPF_MAX + 1] = {
363 	[LWT_BPF_IN]		= { .type = NLA_NESTED, },
364 	[LWT_BPF_OUT]		= { .type = NLA_NESTED, },
365 	[LWT_BPF_XMIT]		= { .type = NLA_NESTED, },
366 	[LWT_BPF_XMIT_HEADROOM]	= { .type = NLA_U32 },
367 };
368 
369 static int bpf_build_state(struct net *net, struct nlattr *nla,
370 			   unsigned int family, const void *cfg,
371 			   struct lwtunnel_state **ts,
372 			   struct netlink_ext_ack *extack)
373 {
374 	struct nlattr *tb[LWT_BPF_MAX + 1];
375 	struct lwtunnel_state *newts;
376 	struct bpf_lwt *bpf;
377 	int ret;
378 
379 	if (family != AF_INET && family != AF_INET6)
380 		return -EAFNOSUPPORT;
381 
382 	ret = nla_parse_nested_deprecated(tb, LWT_BPF_MAX, nla, bpf_nl_policy,
383 					  extack);
384 	if (ret < 0)
385 		return ret;
386 
387 	if (!tb[LWT_BPF_IN] && !tb[LWT_BPF_OUT] && !tb[LWT_BPF_XMIT])
388 		return -EINVAL;
389 
390 	newts = lwtunnel_state_alloc(sizeof(*bpf));
391 	if (!newts)
392 		return -ENOMEM;
393 
394 	newts->type = LWTUNNEL_ENCAP_BPF;
395 	bpf = bpf_lwt_lwtunnel(newts);
396 
397 	if (tb[LWT_BPF_IN]) {
398 		newts->flags |= LWTUNNEL_STATE_INPUT_REDIRECT;
399 		ret = bpf_parse_prog(tb[LWT_BPF_IN], &bpf->in,
400 				     BPF_PROG_TYPE_LWT_IN);
401 		if (ret  < 0)
402 			goto errout;
403 	}
404 
405 	if (tb[LWT_BPF_OUT]) {
406 		newts->flags |= LWTUNNEL_STATE_OUTPUT_REDIRECT;
407 		ret = bpf_parse_prog(tb[LWT_BPF_OUT], &bpf->out,
408 				     BPF_PROG_TYPE_LWT_OUT);
409 		if (ret < 0)
410 			goto errout;
411 	}
412 
413 	if (tb[LWT_BPF_XMIT]) {
414 		newts->flags |= LWTUNNEL_STATE_XMIT_REDIRECT;
415 		ret = bpf_parse_prog(tb[LWT_BPF_XMIT], &bpf->xmit,
416 				     BPF_PROG_TYPE_LWT_XMIT);
417 		if (ret < 0)
418 			goto errout;
419 	}
420 
421 	if (tb[LWT_BPF_XMIT_HEADROOM]) {
422 		u32 headroom = nla_get_u32(tb[LWT_BPF_XMIT_HEADROOM]);
423 
424 		if (headroom > LWT_BPF_MAX_HEADROOM) {
425 			ret = -ERANGE;
426 			goto errout;
427 		}
428 
429 		newts->headroom = headroom;
430 	}
431 
432 	bpf->family = family;
433 	*ts = newts;
434 
435 	return 0;
436 
437 errout:
438 	bpf_destroy_state(newts);
439 	kfree(newts);
440 	return ret;
441 }
442 
443 static int bpf_fill_lwt_prog(struct sk_buff *skb, int attr,
444 			     struct bpf_lwt_prog *prog)
445 {
446 	struct nlattr *nest;
447 
448 	if (!prog->prog)
449 		return 0;
450 
451 	nest = nla_nest_start_noflag(skb, attr);
452 	if (!nest)
453 		return -EMSGSIZE;
454 
455 	if (prog->name &&
456 	    nla_put_string(skb, LWT_BPF_PROG_NAME, prog->name))
457 		return -EMSGSIZE;
458 
459 	return nla_nest_end(skb, nest);
460 }
461 
462 static int bpf_fill_encap_info(struct sk_buff *skb, struct lwtunnel_state *lwt)
463 {
464 	struct bpf_lwt *bpf = bpf_lwt_lwtunnel(lwt);
465 
466 	if (bpf_fill_lwt_prog(skb, LWT_BPF_IN, &bpf->in) < 0 ||
467 	    bpf_fill_lwt_prog(skb, LWT_BPF_OUT, &bpf->out) < 0 ||
468 	    bpf_fill_lwt_prog(skb, LWT_BPF_XMIT, &bpf->xmit) < 0)
469 		return -EMSGSIZE;
470 
471 	return 0;
472 }
473 
474 static int bpf_encap_nlsize(struct lwtunnel_state *lwtstate)
475 {
476 	int nest_len = nla_total_size(sizeof(struct nlattr)) +
477 		       nla_total_size(MAX_PROG_NAME) + /* LWT_BPF_PROG_NAME */
478 		       0;
479 
480 	return nest_len + /* LWT_BPF_IN */
481 	       nest_len + /* LWT_BPF_OUT */
482 	       nest_len + /* LWT_BPF_XMIT */
483 	       0;
484 }
485 
486 static int bpf_lwt_prog_cmp(struct bpf_lwt_prog *a, struct bpf_lwt_prog *b)
487 {
488 	/* FIXME:
489 	 * The LWT state is currently rebuilt for delete requests which
490 	 * results in a new bpf_prog instance. Comparing names for now.
491 	 */
492 	if (!a->name && !b->name)
493 		return 0;
494 
495 	if (!a->name || !b->name)
496 		return 1;
497 
498 	return strcmp(a->name, b->name);
499 }
500 
501 static int bpf_encap_cmp(struct lwtunnel_state *a, struct lwtunnel_state *b)
502 {
503 	struct bpf_lwt *a_bpf = bpf_lwt_lwtunnel(a);
504 	struct bpf_lwt *b_bpf = bpf_lwt_lwtunnel(b);
505 
506 	return bpf_lwt_prog_cmp(&a_bpf->in, &b_bpf->in) ||
507 	       bpf_lwt_prog_cmp(&a_bpf->out, &b_bpf->out) ||
508 	       bpf_lwt_prog_cmp(&a_bpf->xmit, &b_bpf->xmit);
509 }
510 
511 static const struct lwtunnel_encap_ops bpf_encap_ops = {
512 	.build_state	= bpf_build_state,
513 	.destroy_state	= bpf_destroy_state,
514 	.input		= bpf_input,
515 	.output		= bpf_output,
516 	.xmit		= bpf_xmit,
517 	.fill_encap	= bpf_fill_encap_info,
518 	.get_encap_size = bpf_encap_nlsize,
519 	.cmp_encap	= bpf_encap_cmp,
520 	.owner		= THIS_MODULE,
521 };
522 
523 static int handle_gso_type(struct sk_buff *skb, unsigned int gso_type,
524 			   int encap_len)
525 {
526 	struct skb_shared_info *shinfo = skb_shinfo(skb);
527 
528 	gso_type |= SKB_GSO_DODGY;
529 	shinfo->gso_type |= gso_type;
530 	skb_decrease_gso_size(shinfo, encap_len);
531 	shinfo->gso_segs = 0;
532 	return 0;
533 }
534 
535 static int handle_gso_encap(struct sk_buff *skb, bool ipv4, int encap_len)
536 {
537 	int next_hdr_offset;
538 	void *next_hdr;
539 	__u8 protocol;
540 
541 	/* SCTP and UDP_L4 gso need more nuanced handling than what
542 	 * handle_gso_type() does above: skb_decrease_gso_size() is not enough.
543 	 * So at the moment only TCP GSO packets are let through.
544 	 */
545 	if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
546 		return -ENOTSUPP;
547 
548 	if (ipv4) {
549 		protocol = ip_hdr(skb)->protocol;
550 		next_hdr_offset = sizeof(struct iphdr);
551 		next_hdr = skb_network_header(skb) + next_hdr_offset;
552 	} else {
553 		protocol = ipv6_hdr(skb)->nexthdr;
554 		next_hdr_offset = sizeof(struct ipv6hdr);
555 		next_hdr = skb_network_header(skb) + next_hdr_offset;
556 	}
557 
558 	switch (protocol) {
559 	case IPPROTO_GRE:
560 		next_hdr_offset += sizeof(struct gre_base_hdr);
561 		if (next_hdr_offset > encap_len)
562 			return -EINVAL;
563 
564 		if (((struct gre_base_hdr *)next_hdr)->flags & GRE_CSUM)
565 			return handle_gso_type(skb, SKB_GSO_GRE_CSUM,
566 					       encap_len);
567 		return handle_gso_type(skb, SKB_GSO_GRE, encap_len);
568 
569 	case IPPROTO_UDP:
570 		next_hdr_offset += sizeof(struct udphdr);
571 		if (next_hdr_offset > encap_len)
572 			return -EINVAL;
573 
574 		if (((struct udphdr *)next_hdr)->check)
575 			return handle_gso_type(skb, SKB_GSO_UDP_TUNNEL_CSUM,
576 					       encap_len);
577 		return handle_gso_type(skb, SKB_GSO_UDP_TUNNEL, encap_len);
578 
579 	case IPPROTO_IP:
580 	case IPPROTO_IPV6:
581 		if (ipv4)
582 			return handle_gso_type(skb, SKB_GSO_IPXIP4, encap_len);
583 		else
584 			return handle_gso_type(skb, SKB_GSO_IPXIP6, encap_len);
585 
586 	default:
587 		return -EPROTONOSUPPORT;
588 	}
589 }
590 
591 int bpf_lwt_push_ip_encap(struct sk_buff *skb, void *hdr, u32 len, bool ingress)
592 {
593 	struct iphdr *iph;
594 	bool ipv4;
595 	int err;
596 
597 	if (unlikely(len < sizeof(struct iphdr) || len > LWT_BPF_MAX_HEADROOM))
598 		return -EINVAL;
599 
600 	/* validate protocol and length */
601 	iph = (struct iphdr *)hdr;
602 	if (iph->version == 4) {
603 		ipv4 = true;
604 		if (unlikely(len < iph->ihl * 4))
605 			return -EINVAL;
606 	} else if (iph->version == 6) {
607 		ipv4 = false;
608 		if (unlikely(len < sizeof(struct ipv6hdr)))
609 			return -EINVAL;
610 	} else {
611 		return -EINVAL;
612 	}
613 
614 	if (ingress)
615 		err = skb_cow_head(skb, len + skb->mac_len);
616 	else
617 		err = skb_cow_head(skb,
618 				   len + LL_RESERVED_SPACE(skb_dst(skb)->dev));
619 	if (unlikely(err))
620 		return err;
621 
622 	/* push the encap headers and fix pointers */
623 	skb_reset_inner_headers(skb);
624 	skb_reset_inner_mac_header(skb);  /* mac header is not yet set */
625 	skb_set_inner_protocol(skb, skb->protocol);
626 	skb->encapsulation = 1;
627 	skb_push(skb, len);
628 	if (ingress)
629 		skb_postpush_rcsum(skb, iph, len);
630 	skb_reset_network_header(skb);
631 	memcpy(skb_network_header(skb), hdr, len);
632 	bpf_compute_data_pointers(skb);
633 	skb_clear_hash(skb);
634 
635 	if (ipv4) {
636 		skb->protocol = htons(ETH_P_IP);
637 		iph = ip_hdr(skb);
638 
639 		if (!iph->check)
640 			iph->check = ip_fast_csum((unsigned char *)iph,
641 						  iph->ihl);
642 	} else {
643 		skb->protocol = htons(ETH_P_IPV6);
644 	}
645 
646 	if (skb_is_gso(skb))
647 		return handle_gso_encap(skb, ipv4, len);
648 
649 	return 0;
650 }
651 
652 static int __init bpf_lwt_init(void)
653 {
654 	return lwtunnel_encap_add_ops(&bpf_encap_ops, LWTUNNEL_ENCAP_BPF);
655 }
656 
657 subsys_initcall(bpf_lwt_init)
658