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
16static 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(error: -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: csum_unfold(n: uh->check), addend: partial);
47
48 /* setup inner skb. */
49 skb->encapsulation = 0;
50 SKB_GSO_CB(skb)->encap_level = 0;
51 __skb_pull(skb, len: tnl_hlen);
52 skb_reset_mac_header(skb);
53 skb_set_network_header(skb, offset: skb_inner_network_offset(skb));
54 skb_set_transport_header(skb, offset: 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(dst: 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(ptr: segs)) {
89 skb_gso_error_unwind(skb, protocol, pulled_hlen: 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(inner_skb: 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, len: outer_hlen);
115 skb_reset_mac_header(skb);
116 skb_set_network_header(skb, offset: mac_len);
117 skb_set_transport_header(skb, offset: 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(sum: csum_add(csum: partial,
137 addend: (__force __wsum)htonl(len)));
138
139 if (skb->encapsulation || !offload_csum) {
140 uh->check = gso_make_checksum(skb, res: ~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));
149out:
150 return segs;
151}
152
153struct 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(error: -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 new_protocol: protocol, is_ipv6);
184
185out_unlock:
186 rcu_read_unlock();
187
188 return segs;
189}
190EXPORT_SYMBOL(skb_udp_tunnel_segment);
191
192static 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(skb: seg);
203 iph = ip_hdr(skb: seg);
204
205 if (uh->check) {
206 inet_proto_csum_replace4(sum: &uh->check, skb: seg, from: *oldip, to: *newip,
207 pseudohdr: true);
208 inet_proto_csum_replace2(sum: &uh->check, skb: seg, from: *oldport, to: *newport,
209 pseudohdr: false);
210 if (!uh->check)
211 uh->check = CSUM_MANGLED_0;
212 }
213 *oldport = *newport;
214
215 csum_replace4(sum: &iph->check, from: *oldip, to: *newip);
216 *oldip = *newip;
217}
218
219static 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(skb: seg);
227 iph = ip_hdr(skb: seg);
228
229 if ((udp_hdr(skb: seg)->dest == udp_hdr(skb: seg->next)->dest) &&
230 (udp_hdr(skb: seg)->source == udp_hdr(skb: seg->next)->source) &&
231 (ip_hdr(skb: seg)->daddr == ip_hdr(skb: seg->next)->daddr) &&
232 (ip_hdr(skb: seg)->saddr == ip_hdr(skb: seg->next)->saddr))
233 return segs;
234
235 while ((seg = seg->next)) {
236 uh2 = udp_hdr(skb: seg);
237 iph2 = ip_hdr(skb: seg);
238
239 __udpv4_gso_segment_csum(seg,
240 oldip: &iph2->saddr, newip: &iph->saddr,
241 oldport: &uh2->source, newport: &uh->source);
242 __udpv4_gso_segment_csum(seg,
243 oldip: &iph2->daddr, newip: &iph->daddr,
244 oldport: &uh2->dest, newport: &uh->dest);
245 }
246
247 return segs;
248}
249
250static 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, offset: skb_mac_header_len(skb));
257 if (IS_ERR(ptr: 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(segs: skb);
263}
264
265struct 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(error: -EINVAL);
280
281 if (skb_gso_ok(skb: gso_skb, features: 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(skb: gso_skb, features, is_ipv6);
290
291 skb_pull(skb: gso_skb, len: 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(skb: gso_skb, features);
299 if (IS_ERR_OR_NULL(ptr: 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(skb: segs))
310 mss *= skb_shinfo(segs)->gso_segs;
311
312 seg = segs;
313 uh = udp_hdr(skb: 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(csum: csum16_sub(csum: uh->check, addend: uh->len), addend: 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(skb: seg, res: ~check);
339 else
340 uh->check = gso_make_checksum(skb: seg, res: ~check) ? :
341 CSUM_MANGLED_0;
342
343 seg = seg->next;
344 uh = udp_hdr(skb: 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(csum: csum16_sub(csum: uh->check, addend: uh->len), addend: newlen);
351
352 uh->len = newlen;
353 uh->check = check;
354
355 if (seg->ip_summed == CHECKSUM_PARTIAL)
356 gso_reset_checksum(skb: seg, res: ~check);
357 else
358 uh->check = gso_make_checksum(skb: seg, res: ~check) ? : CSUM_MANGLED_0;
359
360 /* update refcount for the packet */
361 if (copy_dtor) {
362 int delta = sum_truesize - gso_skb->truesize;
363
364 /* In some pathological cases, delta can be negative.
365 * We need to either use refcount_add() or refcount_sub_and_test()
366 */
367 if (likely(delta >= 0))
368 refcount_add(i: delta, r: &sk->sk_wmem_alloc);
369 else
370 WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
371 }
372 return segs;
373}
374EXPORT_SYMBOL_GPL(__udp_gso_segment);
375
376static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
377 netdev_features_t features)
378{
379 struct sk_buff *segs = ERR_PTR(error: -EINVAL);
380 unsigned int mss;
381 __wsum csum;
382 struct udphdr *uh;
383 struct iphdr *iph;
384
385 if (skb->encapsulation &&
386 (skb_shinfo(skb)->gso_type &
387 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
388 segs = skb_udp_tunnel_segment(skb, features, false);
389 goto out;
390 }
391
392 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
393 goto out;
394
395 if (!pskb_may_pull(skb, len: sizeof(struct udphdr)))
396 goto out;
397
398 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
399 return __udp_gso_segment(skb, features, false);
400
401 mss = skb_shinfo(skb)->gso_size;
402 if (unlikely(skb->len <= mss))
403 goto out;
404
405 /* Do software UFO. Complete and fill in the UDP checksum as
406 * HW cannot do checksum of UDP packets sent as multiple
407 * IP fragments.
408 */
409
410 uh = udp_hdr(skb);
411 iph = ip_hdr(skb);
412
413 uh->check = 0;
414 csum = skb_checksum(skb, offset: 0, len: skb->len, csum: 0);
415 uh->check = udp_v4_check(len: skb->len, saddr: iph->saddr, daddr: iph->daddr, base: csum);
416 if (uh->check == 0)
417 uh->check = CSUM_MANGLED_0;
418
419 skb->ip_summed = CHECKSUM_UNNECESSARY;
420
421 /* If there is no outer header we can fake a checksum offload
422 * due to the fact that we have already done the checksum in
423 * software prior to segmenting the frame.
424 */
425 if (!skb->encap_hdr_csum)
426 features |= NETIF_F_HW_CSUM;
427
428 /* Fragment the skb. IP headers of the fragments are updated in
429 * inet_gso_segment()
430 */
431 segs = skb_segment(skb, features);
432out:
433 return segs;
434}
435
436static int skb_gro_receive_list(struct sk_buff *p, struct sk_buff *skb)
437{
438 if (unlikely(p->len + skb->len >= 65536))
439 return -E2BIG;
440
441 if (NAPI_GRO_CB(p)->last == p)
442 skb_shinfo(p)->frag_list = skb;
443 else
444 NAPI_GRO_CB(p)->last->next = skb;
445
446 skb_pull(skb, len: skb_gro_offset(skb));
447
448 NAPI_GRO_CB(p)->last = skb;
449 NAPI_GRO_CB(p)->count++;
450 p->data_len += skb->len;
451
452 /* sk ownership - if any - completely transferred to the aggregated packet */
453 skb->destructor = NULL;
454 skb->sk = NULL;
455 p->truesize += skb->truesize;
456 p->len += skb->len;
457
458 NAPI_GRO_CB(skb)->same_flow = 1;
459
460 return 0;
461}
462
463
464#define UDP_GRO_CNT_MAX 64
465static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
466 struct sk_buff *skb)
467{
468 struct udphdr *uh = udp_gro_udphdr(skb);
469 struct sk_buff *pp = NULL;
470 struct udphdr *uh2;
471 struct sk_buff *p;
472 unsigned int ulen;
473 int ret = 0;
474
475 /* requires non zero csum, for symmetry with GSO */
476 if (!uh->check) {
477 NAPI_GRO_CB(skb)->flush = 1;
478 return NULL;
479 }
480
481 /* Do not deal with padded or malicious packets, sorry ! */
482 ulen = ntohs(uh->len);
483 if (ulen <= sizeof(*uh) || ulen != skb_gro_len(skb)) {
484 NAPI_GRO_CB(skb)->flush = 1;
485 return NULL;
486 }
487 /* pull encapsulating udp header */
488 skb_gro_pull(skb, len: sizeof(struct udphdr));
489
490 list_for_each_entry(p, head, list) {
491 if (!NAPI_GRO_CB(p)->same_flow)
492 continue;
493
494 uh2 = udp_hdr(skb: p);
495
496 /* Match ports only, as csum is always non zero */
497 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) {
498 NAPI_GRO_CB(p)->same_flow = 0;
499 continue;
500 }
501
502 if (NAPI_GRO_CB(skb)->is_flist != NAPI_GRO_CB(p)->is_flist) {
503 NAPI_GRO_CB(skb)->flush = 1;
504 return p;
505 }
506
507 /* Terminate the flow on len mismatch or if it grow "too much".
508 * Under small packet flood GRO count could elsewhere grow a lot
509 * leading to excessive truesize values.
510 * On len mismatch merge the first packet shorter than gso_size,
511 * otherwise complete the GRO packet.
512 */
513 if (ulen > ntohs(uh2->len)) {
514 pp = p;
515 } else {
516 if (NAPI_GRO_CB(skb)->is_flist) {
517 if (!pskb_may_pull(skb, len: skb_gro_offset(skb))) {
518 NAPI_GRO_CB(skb)->flush = 1;
519 return NULL;
520 }
521 if ((skb->ip_summed != p->ip_summed) ||
522 (skb->csum_level != p->csum_level)) {
523 NAPI_GRO_CB(skb)->flush = 1;
524 return NULL;
525 }
526 ret = skb_gro_receive_list(p, skb);
527 } else {
528 skb_gro_postpull_rcsum(skb, start: uh,
529 len: sizeof(struct udphdr));
530
531 ret = skb_gro_receive(p, skb);
532 }
533 }
534
535 if (ret || ulen != ntohs(uh2->len) ||
536 NAPI_GRO_CB(p)->count >= UDP_GRO_CNT_MAX)
537 pp = p;
538
539 return pp;
540 }
541
542 /* mismatch, but we never need to flush */
543 return NULL;
544}
545
546struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
547 struct udphdr *uh, struct sock *sk)
548{
549 struct sk_buff *pp = NULL;
550 struct sk_buff *p;
551 struct udphdr *uh2;
552 unsigned int off = skb_gro_offset(skb);
553 int flush = 1;
554
555 /* We can do L4 aggregation only if the packet can't land in a tunnel
556 * otherwise we could corrupt the inner stream. Detecting such packets
557 * cannot be foolproof and the aggregation might still happen in some
558 * cases. Such packets should be caught in udp_unexpected_gso later.
559 */
560 NAPI_GRO_CB(skb)->is_flist = 0;
561 if (!sk || !udp_sk(sk)->gro_receive) {
562 /* If the packet was locally encapsulated in a UDP tunnel that
563 * wasn't detected above, do not GRO.
564 */
565 if (skb->encapsulation)
566 goto out;
567
568 if (skb->dev->features & NETIF_F_GRO_FRAGLIST)
569 NAPI_GRO_CB(skb)->is_flist = sk ? !udp_test_bit(GRO_ENABLED, sk) : 1;
570
571 if ((!sk && (skb->dev->features & NETIF_F_GRO_UDP_FWD)) ||
572 (sk && udp_test_bit(GRO_ENABLED, sk)) || NAPI_GRO_CB(skb)->is_flist)
573 return call_gro_receive(cb: udp_gro_receive_segment, head, skb);
574
575 /* no GRO, be sure flush the current packet */
576 goto out;
577 }
578
579 if (NAPI_GRO_CB(skb)->encap_mark ||
580 (uh->check && skb->ip_summed != CHECKSUM_PARTIAL &&
581 NAPI_GRO_CB(skb)->csum_cnt == 0 &&
582 !NAPI_GRO_CB(skb)->csum_valid))
583 goto out;
584
585 /* mark that this skb passed once through the tunnel gro layer */
586 NAPI_GRO_CB(skb)->encap_mark = 1;
587
588 flush = 0;
589
590 list_for_each_entry(p, head, list) {
591 if (!NAPI_GRO_CB(p)->same_flow)
592 continue;
593
594 uh2 = (struct udphdr *)(p->data + off);
595
596 /* Match ports and either checksums are either both zero
597 * or nonzero.
598 */
599 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
600 (!uh->check ^ !uh2->check)) {
601 NAPI_GRO_CB(p)->same_flow = 0;
602 continue;
603 }
604 }
605
606 skb_gro_pull(skb, len: sizeof(struct udphdr)); /* pull encapsulating udp header */
607 skb_gro_postpull_rcsum(skb, start: uh, len: sizeof(struct udphdr));
608 pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb);
609
610out:
611 skb_gro_flush_final(skb, pp, flush);
612 return pp;
613}
614EXPORT_SYMBOL(udp_gro_receive);
615
616static struct sock *udp4_gro_lookup_skb(struct sk_buff *skb, __be16 sport,
617 __be16 dport)
618{
619 const struct iphdr *iph = skb_gro_network_header(skb);
620 struct net *net = dev_net(dev: skb->dev);
621 int iif, sdif;
622
623 inet_get_iif_sdif(skb, iif: &iif, sdif: &sdif);
624
625 return __udp4_lib_lookup(net, saddr: iph->saddr, sport,
626 daddr: iph->daddr, dport, dif: iif,
627 sdif, tbl: net->ipv4.udp_table, NULL);
628}
629
630INDIRECT_CALLABLE_SCOPE
631struct sk_buff *udp4_gro_receive(struct list_head *head, struct sk_buff *skb)
632{
633 struct udphdr *uh = udp_gro_udphdr(skb);
634 struct sock *sk = NULL;
635 struct sk_buff *pp;
636
637 if (unlikely(!uh))
638 goto flush;
639
640 /* Don't bother verifying checksum if we're going to flush anyway. */
641 if (NAPI_GRO_CB(skb)->flush)
642 goto skip;
643
644 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
645 inet_gro_compute_pseudo))
646 goto flush;
647 else if (uh->check)
648 skb_gro_checksum_try_convert(skb, IPPROTO_UDP,
649 inet_gro_compute_pseudo);
650skip:
651 NAPI_GRO_CB(skb)->is_ipv6 = 0;
652
653 if (static_branch_unlikely(&udp_encap_needed_key))
654 sk = udp4_gro_lookup_skb(skb, sport: uh->source, dport: uh->dest);
655
656 pp = udp_gro_receive(head, skb, uh, sk);
657 return pp;
658
659flush:
660 NAPI_GRO_CB(skb)->flush = 1;
661 return NULL;
662}
663
664static int udp_gro_complete_segment(struct sk_buff *skb)
665{
666 struct udphdr *uh = udp_hdr(skb);
667
668 skb->csum_start = (unsigned char *)uh - skb->head;
669 skb->csum_offset = offsetof(struct udphdr, check);
670 skb->ip_summed = CHECKSUM_PARTIAL;
671
672 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
673 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_L4;
674
675 if (skb->encapsulation)
676 skb->inner_transport_header = skb->transport_header;
677
678 return 0;
679}
680
681int udp_gro_complete(struct sk_buff *skb, int nhoff,
682 udp_lookup_t lookup)
683{
684 __be16 newlen = htons(skb->len - nhoff);
685 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
686 struct sock *sk;
687 int err;
688
689 uh->len = newlen;
690
691 sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb,
692 udp4_lib_lookup_skb, skb, uh->source, uh->dest);
693 if (sk && udp_sk(sk)->gro_complete) {
694 skb_shinfo(skb)->gso_type = uh->check ? SKB_GSO_UDP_TUNNEL_CSUM
695 : SKB_GSO_UDP_TUNNEL;
696
697 /* clear the encap mark, so that inner frag_list gro_complete
698 * can take place
699 */
700 NAPI_GRO_CB(skb)->encap_mark = 0;
701
702 /* Set encapsulation before calling into inner gro_complete()
703 * functions to make them set up the inner offsets.
704 */
705 skb->encapsulation = 1;
706 err = udp_sk(sk)->gro_complete(sk, skb,
707 nhoff + sizeof(struct udphdr));
708 } else {
709 err = udp_gro_complete_segment(skb);
710 }
711
712 if (skb->remcsum_offload)
713 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
714
715 return err;
716}
717EXPORT_SYMBOL(udp_gro_complete);
718
719INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff)
720{
721 const struct iphdr *iph = ip_hdr(skb);
722 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
723
724 /* do fraglist only if there is no outer UDP encap (or we already processed it) */
725 if (NAPI_GRO_CB(skb)->is_flist && !NAPI_GRO_CB(skb)->encap_mark) {
726 uh->len = htons(skb->len - nhoff);
727
728 skb_shinfo(skb)->gso_type |= (SKB_GSO_FRAGLIST|SKB_GSO_UDP_L4);
729 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
730
731 __skb_incr_checksum_unnecessary(skb);
732
733 return 0;
734 }
735
736 if (uh->check)
737 uh->check = ~udp_v4_check(len: skb->len - nhoff, saddr: iph->saddr,
738 daddr: iph->daddr, base: 0);
739
740 return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
741}
742
743int __init udpv4_offload_init(void)
744{
745 net_hotdata.udpv4_offload = (struct net_offload) {
746 .callbacks = {
747 .gso_segment = udp4_ufo_fragment,
748 .gro_receive = udp4_gro_receive,
749 .gro_complete = udp4_gro_complete,
750 },
751 };
752 return inet_add_offload(prot: &net_hotdata.udpv4_offload, IPPROTO_UDP);
753}
754

source code of linux/net/ipv4/udp_offload.c