xref: /linux/net/ipv4/udp_offload.c (revision 42d37fc0c819b81f6f6afd108b55d04ba9d32d0f)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *	IPV4 GSO/GRO offload support
4  *	Linux INET implementation
5  *
6  *	UDPv4 GSO support
7  */
8 
9 #include <linux/skbuff.h>
10 #include <net/gro.h>
11 #include <net/gso.h>
12 #include <net/udp.h>
13 #include <net/protocol.h>
14 #include <net/inet_common.h>
15 
16 static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
17 	netdev_features_t features,
18 	struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
19 					     netdev_features_t features),
20 	__be16 new_protocol, bool is_ipv6)
21 {
22 	int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
23 	bool remcsum, need_csum, offload_csum, gso_partial;
24 	struct sk_buff *segs = ERR_PTR(-EINVAL);
25 	struct udphdr *uh = udp_hdr(skb);
26 	u16 mac_offset = skb->mac_header;
27 	__be16 protocol = skb->protocol;
28 	u16 mac_len = skb->mac_len;
29 	int udp_offset, outer_hlen;
30 	__wsum partial;
31 	bool need_ipsec;
32 
33 	if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
34 		goto out;
35 
36 	/* Adjust partial header checksum to negate old length.
37 	 * We cannot rely on the value contained in uh->len as it is
38 	 * possible that the actual value exceeds the boundaries of the
39 	 * 16 bit length field due to the header being added outside of an
40 	 * IP or IPv6 frame that was already limited to 64K - 1.
41 	 */
42 	if (skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL)
43 		partial = (__force __wsum)uh->len;
44 	else
45 		partial = (__force __wsum)htonl(skb->len);
46 	partial = csum_sub(csum_unfold(uh->check), partial);
47 
48 	/* setup inner skb. */
49 	skb->encapsulation = 0;
50 	SKB_GSO_CB(skb)->encap_level = 0;
51 	__skb_pull(skb, tnl_hlen);
52 	skb_reset_mac_header(skb);
53 	skb_set_network_header(skb, skb_inner_network_offset(skb));
54 	skb_set_transport_header(skb, skb_inner_transport_offset(skb));
55 	skb->mac_len = skb_inner_network_offset(skb);
56 	skb->protocol = new_protocol;
57 
58 	need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
59 	skb->encap_hdr_csum = need_csum;
60 
61 	remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
62 	skb->remcsum_offload = remcsum;
63 
64 	need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb));
65 	/* Try to offload checksum if possible */
66 	offload_csum = !!(need_csum &&
67 			  !need_ipsec &&
68 			  (skb->dev->features &
69 			   (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) :
70 				      (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM))));
71 
72 	features &= skb->dev->hw_enc_features;
73 	if (need_csum)
74 		features &= ~NETIF_F_SCTP_CRC;
75 
76 	/* The only checksum offload we care about from here on out is the
77 	 * outer one so strip the existing checksum feature flags and
78 	 * instead set the flag based on our outer checksum offload value.
79 	 */
80 	if (remcsum) {
81 		features &= ~NETIF_F_CSUM_MASK;
82 		if (!need_csum || offload_csum)
83 			features |= NETIF_F_HW_CSUM;
84 	}
85 
86 	/* segment inner packet. */
87 	segs = gso_inner_segment(skb, features);
88 	if (IS_ERR_OR_NULL(segs)) {
89 		skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
90 				     mac_len);
91 		goto out;
92 	}
93 
94 	gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
95 
96 	outer_hlen = skb_tnl_header_len(skb);
97 	udp_offset = outer_hlen - tnl_hlen;
98 	skb = segs;
99 	do {
100 		unsigned int len;
101 
102 		if (remcsum)
103 			skb->ip_summed = CHECKSUM_NONE;
104 
105 		/* Set up inner headers if we are offloading inner checksum */
106 		if (skb->ip_summed == CHECKSUM_PARTIAL) {
107 			skb_reset_inner_headers(skb);
108 			skb->encapsulation = 1;
109 		}
110 
111 		skb->mac_len = mac_len;
112 		skb->protocol = protocol;
113 
114 		__skb_push(skb, outer_hlen);
115 		skb_reset_mac_header(skb);
116 		skb_set_network_header(skb, mac_len);
117 		skb_set_transport_header(skb, udp_offset);
118 		len = skb->len - udp_offset;
119 		uh = udp_hdr(skb);
120 
121 		/* If we are only performing partial GSO the inner header
122 		 * will be using a length value equal to only one MSS sized
123 		 * segment instead of the entire frame.
124 		 */
125 		if (gso_partial && skb_is_gso(skb)) {
126 			uh->len = htons(skb_shinfo(skb)->gso_size +
127 					SKB_GSO_CB(skb)->data_offset +
128 					skb->head - (unsigned char *)uh);
129 		} else {
130 			uh->len = htons(len);
131 		}
132 
133 		if (!need_csum)
134 			continue;
135 
136 		uh->check = ~csum_fold(csum_add(partial,
137 				       (__force __wsum)htonl(len)));
138 
139 		if (skb->encapsulation || !offload_csum) {
140 			uh->check = gso_make_checksum(skb, ~uh->check);
141 			if (uh->check == 0)
142 				uh->check = CSUM_MANGLED_0;
143 		} else {
144 			skb->ip_summed = CHECKSUM_PARTIAL;
145 			skb->csum_start = skb_transport_header(skb) - skb->head;
146 			skb->csum_offset = offsetof(struct udphdr, check);
147 		}
148 	} while ((skb = skb->next));
149 out:
150 	return segs;
151 }
152 
153 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
154 				       netdev_features_t features,
155 				       bool is_ipv6)
156 {
157 	const struct net_offload __rcu **offloads;
158 	__be16 protocol = skb->protocol;
159 	const struct net_offload *ops;
160 	struct sk_buff *segs = ERR_PTR(-EINVAL);
161 	struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
162 					     netdev_features_t features);
163 
164 	rcu_read_lock();
165 
166 	switch (skb->inner_protocol_type) {
167 	case ENCAP_TYPE_ETHER:
168 		protocol = skb->inner_protocol;
169 		gso_inner_segment = skb_mac_gso_segment;
170 		break;
171 	case ENCAP_TYPE_IPPROTO:
172 		offloads = is_ipv6 ? inet6_offloads : inet_offloads;
173 		ops = rcu_dereference(offloads[skb->inner_ipproto]);
174 		if (!ops || !ops->callbacks.gso_segment)
175 			goto out_unlock;
176 		gso_inner_segment = ops->callbacks.gso_segment;
177 		break;
178 	default:
179 		goto out_unlock;
180 	}
181 
182 	segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
183 					protocol, is_ipv6);
184 
185 out_unlock:
186 	rcu_read_unlock();
187 
188 	return segs;
189 }
190 EXPORT_SYMBOL(skb_udp_tunnel_segment);
191 
192 static void __udpv4_gso_segment_csum(struct sk_buff *seg,
193 				     __be32 *oldip, __be32 *newip,
194 				     __be16 *oldport, __be16 *newport)
195 {
196 	struct udphdr *uh;
197 	struct iphdr *iph;
198 
199 	if (*oldip == *newip && *oldport == *newport)
200 		return;
201 
202 	uh = udp_hdr(seg);
203 	iph = ip_hdr(seg);
204 
205 	if (uh->check) {
206 		inet_proto_csum_replace4(&uh->check, seg, *oldip, *newip,
207 					 true);
208 		inet_proto_csum_replace2(&uh->check, seg, *oldport, *newport,
209 					 false);
210 		if (!uh->check)
211 			uh->check = CSUM_MANGLED_0;
212 	}
213 	*oldport = *newport;
214 
215 	csum_replace4(&iph->check, *oldip, *newip);
216 	*oldip = *newip;
217 }
218 
219 static struct sk_buff *__udpv4_gso_segment_list_csum(struct sk_buff *segs)
220 {
221 	struct sk_buff *seg;
222 	struct udphdr *uh, *uh2;
223 	struct iphdr *iph, *iph2;
224 
225 	seg = segs;
226 	uh = udp_hdr(seg);
227 	iph = ip_hdr(seg);
228 
229 	if ((udp_hdr(seg)->dest == udp_hdr(seg->next)->dest) &&
230 	    (udp_hdr(seg)->source == udp_hdr(seg->next)->source) &&
231 	    (ip_hdr(seg)->daddr == ip_hdr(seg->next)->daddr) &&
232 	    (ip_hdr(seg)->saddr == ip_hdr(seg->next)->saddr))
233 		return segs;
234 
235 	while ((seg = seg->next)) {
236 		uh2 = udp_hdr(seg);
237 		iph2 = ip_hdr(seg);
238 
239 		__udpv4_gso_segment_csum(seg,
240 					 &iph2->saddr, &iph->saddr,
241 					 &uh2->source, &uh->source);
242 		__udpv4_gso_segment_csum(seg,
243 					 &iph2->daddr, &iph->daddr,
244 					 &uh2->dest, &uh->dest);
245 	}
246 
247 	return segs;
248 }
249 
250 static struct sk_buff *__udp_gso_segment_list(struct sk_buff *skb,
251 					      netdev_features_t features,
252 					      bool is_ipv6)
253 {
254 	unsigned int mss = skb_shinfo(skb)->gso_size;
255 
256 	skb = skb_segment_list(skb, features, skb_mac_header_len(skb));
257 	if (IS_ERR(skb))
258 		return skb;
259 
260 	udp_hdr(skb)->len = htons(sizeof(struct udphdr) + mss);
261 
262 	return is_ipv6 ? skb : __udpv4_gso_segment_list_csum(skb);
263 }
264 
265 struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
266 				  netdev_features_t features, bool is_ipv6)
267 {
268 	struct sock *sk = gso_skb->sk;
269 	unsigned int sum_truesize = 0;
270 	struct sk_buff *segs, *seg;
271 	struct udphdr *uh;
272 	unsigned int mss;
273 	bool copy_dtor;
274 	__sum16 check;
275 	__be16 newlen;
276 
277 	mss = skb_shinfo(gso_skb)->gso_size;
278 	if (gso_skb->len <= sizeof(*uh) + mss)
279 		return ERR_PTR(-EINVAL);
280 
281 	if (skb_gso_ok(gso_skb, features | NETIF_F_GSO_ROBUST)) {
282 		/* Packet is from an untrusted source, reset gso_segs. */
283 		skb_shinfo(gso_skb)->gso_segs = DIV_ROUND_UP(gso_skb->len - sizeof(*uh),
284 							     mss);
285 		return NULL;
286 	}
287 
288 	if (skb_shinfo(gso_skb)->gso_type & SKB_GSO_FRAGLIST)
289 		return __udp_gso_segment_list(gso_skb, features, is_ipv6);
290 
291 	skb_pull(gso_skb, sizeof(*uh));
292 
293 	/* clear destructor to avoid skb_segment assigning it to tail */
294 	copy_dtor = gso_skb->destructor == sock_wfree;
295 	if (copy_dtor)
296 		gso_skb->destructor = NULL;
297 
298 	segs = skb_segment(gso_skb, features);
299 	if (IS_ERR_OR_NULL(segs)) {
300 		if (copy_dtor)
301 			gso_skb->destructor = sock_wfree;
302 		return segs;
303 	}
304 
305 	/* GSO partial and frag_list segmentation only requires splitting
306 	 * the frame into an MSS multiple and possibly a remainder, both
307 	 * cases return a GSO skb. So update the mss now.
308 	 */
309 	if (skb_is_gso(segs))
310 		mss *= skb_shinfo(segs)->gso_segs;
311 
312 	seg = segs;
313 	uh = udp_hdr(seg);
314 
315 	/* preserve TX timestamp flags and TS key for first segment */
316 	skb_shinfo(seg)->tskey = skb_shinfo(gso_skb)->tskey;
317 	skb_shinfo(seg)->tx_flags |=
318 			(skb_shinfo(gso_skb)->tx_flags & SKBTX_ANY_TSTAMP);
319 
320 	/* compute checksum adjustment based on old length versus new */
321 	newlen = htons(sizeof(*uh) + mss);
322 	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
323 
324 	for (;;) {
325 		if (copy_dtor) {
326 			seg->destructor = sock_wfree;
327 			seg->sk = sk;
328 			sum_truesize += seg->truesize;
329 		}
330 
331 		if (!seg->next)
332 			break;
333 
334 		uh->len = newlen;
335 		uh->check = check;
336 
337 		if (seg->ip_summed == CHECKSUM_PARTIAL)
338 			gso_reset_checksum(seg, ~check);
339 		else
340 			uh->check = gso_make_checksum(seg, ~check) ? :
341 				    CSUM_MANGLED_0;
342 
343 		seg = seg->next;
344 		uh = udp_hdr(seg);
345 	}
346 
347 	/* last packet can be partial gso_size, account for that in checksum */
348 	newlen = htons(skb_tail_pointer(seg) - skb_transport_header(seg) +
349 		       seg->data_len);
350 	check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
351 
352 	uh->len = newlen;
353 	uh->check = check;
354 
355 	if (seg->ip_summed == CHECKSUM_PARTIAL)
356 		gso_reset_checksum(seg, ~check);
357 	else
358 		uh->check = gso_make_checksum(seg, ~check) ? : CSUM_MANGLED_0;
359 
360 	/* On the TX path, CHECKSUM_NONE and CHECKSUM_UNNECESSARY have the same
361 	 * meaning. However, check for bad offloads in the GSO stack expects the
362 	 * latter, if the checksum was calculated in software. To vouch for the
363 	 * segment skbs we actually need to set it on the gso_skb.
364 	 */
365 	if (gso_skb->ip_summed == CHECKSUM_NONE)
366 		gso_skb->ip_summed = CHECKSUM_UNNECESSARY;
367 
368 	/* update refcount for the packet */
369 	if (copy_dtor) {
370 		int delta = sum_truesize - gso_skb->truesize;
371 
372 		/* In some pathological cases, delta can be negative.
373 		 * We need to either use refcount_add() or refcount_sub_and_test()
374 		 */
375 		if (likely(delta >= 0))
376 			refcount_add(delta, &sk->sk_wmem_alloc);
377 		else
378 			WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
379 	}
380 	return segs;
381 }
382 EXPORT_SYMBOL_GPL(__udp_gso_segment);
383 
384 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
385 					 netdev_features_t features)
386 {
387 	struct sk_buff *segs = ERR_PTR(-EINVAL);
388 	unsigned int mss;
389 	__wsum csum;
390 	struct udphdr *uh;
391 	struct iphdr *iph;
392 
393 	if (skb->encapsulation &&
394 	    (skb_shinfo(skb)->gso_type &
395 	     (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
396 		segs = skb_udp_tunnel_segment(skb, features, false);
397 		goto out;
398 	}
399 
400 	if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
401 		goto out;
402 
403 	if (!pskb_may_pull(skb, sizeof(struct udphdr)))
404 		goto out;
405 
406 	if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
407 		return __udp_gso_segment(skb, features, false);
408 
409 	mss = skb_shinfo(skb)->gso_size;
410 	if (unlikely(skb->len <= mss))
411 		goto out;
412 
413 	/* Do software UFO. Complete and fill in the UDP checksum as
414 	 * HW cannot do checksum of UDP packets sent as multiple
415 	 * IP fragments.
416 	 */
417 
418 	uh = udp_hdr(skb);
419 	iph = ip_hdr(skb);
420 
421 	uh->check = 0;
422 	csum = skb_checksum(skb, 0, skb->len, 0);
423 	uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
424 	if (uh->check == 0)
425 		uh->check = CSUM_MANGLED_0;
426 
427 	skb->ip_summed = CHECKSUM_UNNECESSARY;
428 
429 	/* If there is no outer header we can fake a checksum offload
430 	 * due to the fact that we have already done the checksum in
431 	 * software prior to segmenting the frame.
432 	 */
433 	if (!skb->encap_hdr_csum)
434 		features |= NETIF_F_HW_CSUM;
435 
436 	/* Fragment the skb. IP headers of the fragments are updated in
437 	 * inet_gso_segment()
438 	 */
439 	segs = skb_segment(skb, features);
440 out:
441 	return segs;
442 }
443 
444 
445 #define UDP_GRO_CNT_MAX 64
446 static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
447 					       struct sk_buff *skb)
448 {
449 	struct udphdr *uh = udp_gro_udphdr(skb);
450 	struct sk_buff *pp = NULL;
451 	struct udphdr *uh2;
452 	struct sk_buff *p;
453 	unsigned int ulen;
454 	int ret = 0;
455 	int flush;
456 
457 	/* requires non zero csum, for symmetry with GSO */
458 	if (!uh->check) {
459 		NAPI_GRO_CB(skb)->flush = 1;
460 		return NULL;
461 	}
462 
463 	/* Do not deal with padded or malicious packets, sorry ! */
464 	ulen = ntohs(uh->len);
465 	if (ulen <= sizeof(*uh) || ulen != skb_gro_len(skb)) {
466 		NAPI_GRO_CB(skb)->flush = 1;
467 		return NULL;
468 	}
469 	/* pull encapsulating udp header */
470 	skb_gro_pull(skb, sizeof(struct udphdr));
471 
472 	list_for_each_entry(p, head, list) {
473 		if (!NAPI_GRO_CB(p)->same_flow)
474 			continue;
475 
476 		uh2 = udp_hdr(p);
477 
478 		/* Match ports only, as csum is always non zero */
479 		if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) {
480 			NAPI_GRO_CB(p)->same_flow = 0;
481 			continue;
482 		}
483 
484 		if (NAPI_GRO_CB(skb)->is_flist != NAPI_GRO_CB(p)->is_flist) {
485 			NAPI_GRO_CB(skb)->flush = 1;
486 			return p;
487 		}
488 
489 		flush = gro_receive_network_flush(uh, uh2, p);
490 
491 		/* Terminate the flow on len mismatch or if it grow "too much".
492 		 * Under small packet flood GRO count could elsewhere grow a lot
493 		 * leading to excessive truesize values.
494 		 * On len mismatch merge the first packet shorter than gso_size,
495 		 * otherwise complete the GRO packet.
496 		 */
497 		if (ulen > ntohs(uh2->len) || flush) {
498 			pp = p;
499 		} else {
500 			if (NAPI_GRO_CB(skb)->is_flist) {
501 				if (!pskb_may_pull(skb, skb_gro_offset(skb))) {
502 					NAPI_GRO_CB(skb)->flush = 1;
503 					return NULL;
504 				}
505 				if ((skb->ip_summed != p->ip_summed) ||
506 				    (skb->csum_level != p->csum_level)) {
507 					NAPI_GRO_CB(skb)->flush = 1;
508 					return NULL;
509 				}
510 				ret = skb_gro_receive_list(p, skb);
511 			} else {
512 				skb_gro_postpull_rcsum(skb, uh,
513 						       sizeof(struct udphdr));
514 
515 				ret = skb_gro_receive(p, skb);
516 			}
517 		}
518 
519 		if (ret || ulen != ntohs(uh2->len) ||
520 		    NAPI_GRO_CB(p)->count >= UDP_GRO_CNT_MAX)
521 			pp = p;
522 
523 		return pp;
524 	}
525 
526 	/* mismatch, but we never need to flush */
527 	return NULL;
528 }
529 
530 struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
531 				struct udphdr *uh, struct sock *sk)
532 {
533 	struct sk_buff *pp = NULL;
534 	struct sk_buff *p;
535 	struct udphdr *uh2;
536 	unsigned int off = skb_gro_offset(skb);
537 	int flush = 1;
538 
539 	/* We can do L4 aggregation only if the packet can't land in a tunnel
540 	 * otherwise we could corrupt the inner stream. Detecting such packets
541 	 * cannot be foolproof and the aggregation might still happen in some
542 	 * cases. Such packets should be caught in udp_unexpected_gso later.
543 	 */
544 	NAPI_GRO_CB(skb)->is_flist = 0;
545 	if (!sk || !udp_sk(sk)->gro_receive) {
546 		/* If the packet was locally encapsulated in a UDP tunnel that
547 		 * wasn't detected above, do not GRO.
548 		 */
549 		if (skb->encapsulation)
550 			goto out;
551 
552 		if (skb->dev->features & NETIF_F_GRO_FRAGLIST)
553 			NAPI_GRO_CB(skb)->is_flist = sk ? !udp_test_bit(GRO_ENABLED, sk) : 1;
554 
555 		if ((!sk && (skb->dev->features & NETIF_F_GRO_UDP_FWD)) ||
556 		    (sk && udp_test_bit(GRO_ENABLED, sk)) || NAPI_GRO_CB(skb)->is_flist)
557 			return call_gro_receive(udp_gro_receive_segment, head, skb);
558 
559 		/* no GRO, be sure flush the current packet */
560 		goto out;
561 	}
562 
563 	if (NAPI_GRO_CB(skb)->encap_mark ||
564 	    (uh->check && skb->ip_summed != CHECKSUM_PARTIAL &&
565 	     NAPI_GRO_CB(skb)->csum_cnt == 0 &&
566 	     !NAPI_GRO_CB(skb)->csum_valid))
567 		goto out;
568 
569 	/* mark that this skb passed once through the tunnel gro layer */
570 	NAPI_GRO_CB(skb)->encap_mark = 1;
571 
572 	flush = 0;
573 
574 	list_for_each_entry(p, head, list) {
575 		if (!NAPI_GRO_CB(p)->same_flow)
576 			continue;
577 
578 		uh2 = (struct udphdr   *)(p->data + off);
579 
580 		/* Match ports and either checksums are either both zero
581 		 * or nonzero.
582 		 */
583 		if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
584 		    (!uh->check ^ !uh2->check)) {
585 			NAPI_GRO_CB(p)->same_flow = 0;
586 			continue;
587 		}
588 	}
589 
590 	skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
591 	skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
592 	pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb);
593 
594 out:
595 	skb_gro_flush_final(skb, pp, flush);
596 	return pp;
597 }
598 EXPORT_SYMBOL(udp_gro_receive);
599 
600 static struct sock *udp4_gro_lookup_skb(struct sk_buff *skb, __be16 sport,
601 					__be16 dport)
602 {
603 	const struct iphdr *iph = skb_gro_network_header(skb);
604 	struct net *net = dev_net(skb->dev);
605 	int iif, sdif;
606 
607 	inet_get_iif_sdif(skb, &iif, &sdif);
608 
609 	return __udp4_lib_lookup(net, iph->saddr, sport,
610 				 iph->daddr, dport, iif,
611 				 sdif, net->ipv4.udp_table, NULL);
612 }
613 
614 INDIRECT_CALLABLE_SCOPE
615 struct sk_buff *udp4_gro_receive(struct list_head *head, struct sk_buff *skb)
616 {
617 	struct udphdr *uh = udp_gro_udphdr(skb);
618 	struct sock *sk = NULL;
619 	struct sk_buff *pp;
620 
621 	if (unlikely(!uh))
622 		goto flush;
623 
624 	/* Don't bother verifying checksum if we're going to flush anyway. */
625 	if (NAPI_GRO_CB(skb)->flush)
626 		goto skip;
627 
628 	if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
629 						 inet_gro_compute_pseudo))
630 		goto flush;
631 	else if (uh->check)
632 		skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
633 					     inet_gro_compute_pseudo);
634 skip:
635 	NAPI_GRO_CB(skb)->is_ipv6 = 0;
636 
637 	if (static_branch_unlikely(&udp_encap_needed_key))
638 		sk = udp4_gro_lookup_skb(skb, uh->source, uh->dest);
639 
640 	pp = udp_gro_receive(head, skb, uh, sk);
641 	return pp;
642 
643 flush:
644 	NAPI_GRO_CB(skb)->flush = 1;
645 	return NULL;
646 }
647 
648 static int udp_gro_complete_segment(struct sk_buff *skb)
649 {
650 	struct udphdr *uh = udp_hdr(skb);
651 
652 	skb->csum_start = (unsigned char *)uh - skb->head;
653 	skb->csum_offset = offsetof(struct udphdr, check);
654 	skb->ip_summed = CHECKSUM_PARTIAL;
655 
656 	skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
657 	skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_L4;
658 
659 	if (skb->encapsulation)
660 		skb->inner_transport_header = skb->transport_header;
661 
662 	return 0;
663 }
664 
665 int udp_gro_complete(struct sk_buff *skb, int nhoff,
666 		     udp_lookup_t lookup)
667 {
668 	__be16 newlen = htons(skb->len - nhoff);
669 	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
670 	struct sock *sk;
671 	int err;
672 
673 	uh->len = newlen;
674 
675 	sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb,
676 				udp4_lib_lookup_skb, skb, uh->source, uh->dest);
677 	if (sk && udp_sk(sk)->gro_complete) {
678 		skb_shinfo(skb)->gso_type = uh->check ? SKB_GSO_UDP_TUNNEL_CSUM
679 					: SKB_GSO_UDP_TUNNEL;
680 
681 		/* clear the encap mark, so that inner frag_list gro_complete
682 		 * can take place
683 		 */
684 		NAPI_GRO_CB(skb)->encap_mark = 0;
685 
686 		/* Set encapsulation before calling into inner gro_complete()
687 		 * functions to make them set up the inner offsets.
688 		 */
689 		skb->encapsulation = 1;
690 		err = udp_sk(sk)->gro_complete(sk, skb,
691 				nhoff + sizeof(struct udphdr));
692 	} else {
693 		err = udp_gro_complete_segment(skb);
694 	}
695 
696 	if (skb->remcsum_offload)
697 		skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
698 
699 	return err;
700 }
701 EXPORT_SYMBOL(udp_gro_complete);
702 
703 INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff)
704 {
705 	const u16 offset = NAPI_GRO_CB(skb)->network_offsets[skb->encapsulation];
706 	const struct iphdr *iph = (struct iphdr *)(skb->data + offset);
707 	struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
708 
709 	/* do fraglist only if there is no outer UDP encap (or we already processed it) */
710 	if (NAPI_GRO_CB(skb)->is_flist && !NAPI_GRO_CB(skb)->encap_mark) {
711 		uh->len = htons(skb->len - nhoff);
712 
713 		skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
714 		skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
715 
716 		__skb_incr_checksum_unnecessary(skb);
717 
718 		return 0;
719 	}
720 
721 	if (uh->check)
722 		uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
723 					  iph->daddr, 0);
724 
725 	return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
726 }
727 
728 int __init udpv4_offload_init(void)
729 {
730 	net_hotdata.udpv4_offload = (struct net_offload) {
731 		.callbacks = {
732 			.gso_segment = udp4_ufo_fragment,
733 			.gro_receive  =	udp4_gro_receive,
734 			.gro_complete =	udp4_gro_complete,
735 		},
736 	};
737 	return inet_add_offload(&net_hotdata.udpv4_offload, IPPROTO_UDP);
738 }
739