1/*
2 * IPV4 GSO/GRO offload support
3 * Linux INET implementation
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
9 *
10 * UDPv4 GSO support
11 */
12
13#include <linux/skbuff.h>
14#include <net/udp.h>
15#include <net/protocol.h>
16#include <net/inet_common.h>
17
18static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
19 netdev_features_t features,
20 struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
21 netdev_features_t features),
22 __be16 new_protocol, bool is_ipv6)
23{
24 int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
25 bool remcsum, need_csum, offload_csum, gso_partial;
26 struct sk_buff *segs = ERR_PTR(-EINVAL);
27 struct udphdr *uh = udp_hdr(skb);
28 u16 mac_offset = skb->mac_header;
29 __be16 protocol = skb->protocol;
30 u16 mac_len = skb->mac_len;
31 int udp_offset, outer_hlen;
32 __wsum partial;
33 bool need_ipsec;
34
35 if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
36 goto out;
37
38 /* Adjust partial header checksum to negate old length.
39 * We cannot rely on the value contained in uh->len as it is
40 * possible that the actual value exceeds the boundaries of the
41 * 16 bit length field due to the header being added outside of an
42 * IP or IPv6 frame that was already limited to 64K - 1.
43 */
44 if (skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL)
45 partial = (__force __wsum)uh->len;
46 else
47 partial = (__force __wsum)htonl(skb->len);
48 partial = csum_sub(csum_unfold(uh->check), partial);
49
50 /* setup inner skb. */
51 skb->encapsulation = 0;
52 SKB_GSO_CB(skb)->encap_level = 0;
53 __skb_pull(skb, tnl_hlen);
54 skb_reset_mac_header(skb);
55 skb_set_network_header(skb, skb_inner_network_offset(skb));
56 skb->mac_len = skb_inner_network_offset(skb);
57 skb->protocol = new_protocol;
58
59 need_csum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP_TUNNEL_CSUM);
60 skb->encap_hdr_csum = need_csum;
61
62 remcsum = !!(skb_shinfo(skb)->gso_type & SKB_GSO_TUNNEL_REMCSUM);
63 skb->remcsum_offload = remcsum;
64
65 need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb));
66 /* Try to offload checksum if possible */
67 offload_csum = !!(need_csum &&
68 !need_ipsec &&
69 (skb->dev->features &
70 (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) :
71 (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM))));
72
73 features &= skb->dev->hw_enc_features;
74
75 /* The only checksum offload we care about from here on out is the
76 * outer one so strip the existing checksum feature flags and
77 * instead set the flag based on our outer checksum offload value.
78 */
79 if (remcsum) {
80 features &= ~NETIF_F_CSUM_MASK;
81 if (!need_csum || offload_csum)
82 features |= NETIF_F_HW_CSUM;
83 }
84
85 /* segment inner packet. */
86 segs = gso_inner_segment(skb, features);
87 if (IS_ERR_OR_NULL(segs)) {
88 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
89 mac_len);
90 goto out;
91 }
92
93 gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
94
95 outer_hlen = skb_tnl_header_len(skb);
96 udp_offset = outer_hlen - tnl_hlen;
97 skb = segs;
98 do {
99 unsigned int len;
100
101 if (remcsum)
102 skb->ip_summed = CHECKSUM_NONE;
103
104 /* Set up inner headers if we are offloading inner checksum */
105 if (skb->ip_summed == CHECKSUM_PARTIAL) {
106 skb_reset_inner_headers(skb);
107 skb->encapsulation = 1;
108 }
109
110 skb->mac_len = mac_len;
111 skb->protocol = protocol;
112
113 __skb_push(skb, outer_hlen);
114 skb_reset_mac_header(skb);
115 skb_set_network_header(skb, mac_len);
116 skb_set_transport_header(skb, udp_offset);
117 len = skb->len - udp_offset;
118 uh = udp_hdr(skb);
119
120 /* If we are only performing partial GSO the inner header
121 * will be using a length value equal to only one MSS sized
122 * segment instead of the entire frame.
123 */
124 if (gso_partial && skb_is_gso(skb)) {
125 uh->len = htons(skb_shinfo(skb)->gso_size +
126 SKB_GSO_CB(skb)->data_offset +
127 skb->head - (unsigned char *)uh);
128 } else {
129 uh->len = htons(len);
130 }
131
132 if (!need_csum)
133 continue;
134
135 uh->check = ~csum_fold(csum_add(partial,
136 (__force __wsum)htonl(len)));
137
138 if (skb->encapsulation || !offload_csum) {
139 uh->check = gso_make_checksum(skb, ~uh->check);
140 if (uh->check == 0)
141 uh->check = CSUM_MANGLED_0;
142 } else {
143 skb->ip_summed = CHECKSUM_PARTIAL;
144 skb->csum_start = skb_transport_header(skb) - skb->head;
145 skb->csum_offset = offsetof(struct udphdr, check);
146 }
147 } while ((skb = skb->next));
148out:
149 return segs;
150}
151
152struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
153 netdev_features_t features,
154 bool is_ipv6)
155{
156 __be16 protocol = skb->protocol;
157 const struct net_offload **offloads;
158 const struct net_offload *ops;
159 struct sk_buff *segs = ERR_PTR(-EINVAL);
160 struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
161 netdev_features_t features);
162
163 rcu_read_lock();
164
165 switch (skb->inner_protocol_type) {
166 case ENCAP_TYPE_ETHER:
167 protocol = skb->inner_protocol;
168 gso_inner_segment = skb_mac_gso_segment;
169 break;
170 case ENCAP_TYPE_IPPROTO:
171 offloads = is_ipv6 ? inet6_offloads : inet_offloads;
172 ops = rcu_dereference(offloads[skb->inner_ipproto]);
173 if (!ops || !ops->callbacks.gso_segment)
174 goto out_unlock;
175 gso_inner_segment = ops->callbacks.gso_segment;
176 break;
177 default:
178 goto out_unlock;
179 }
180
181 segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
182 protocol, is_ipv6);
183
184out_unlock:
185 rcu_read_unlock();
186
187 return segs;
188}
189EXPORT_SYMBOL(skb_udp_tunnel_segment);
190
191struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
192 netdev_features_t features)
193{
194 struct sock *sk = gso_skb->sk;
195 unsigned int sum_truesize = 0;
196 struct sk_buff *segs, *seg;
197 struct udphdr *uh;
198 unsigned int mss;
199 bool copy_dtor;
200 __sum16 check;
201 __be16 newlen;
202
203 mss = skb_shinfo(gso_skb)->gso_size;
204 if (gso_skb->len <= sizeof(*uh) + mss)
205 return ERR_PTR(-EINVAL);
206
207 skb_pull(gso_skb, sizeof(*uh));
208
209 /* clear destructor to avoid skb_segment assigning it to tail */
210 copy_dtor = gso_skb->destructor == sock_wfree;
211 if (copy_dtor)
212 gso_skb->destructor = NULL;
213
214 segs = skb_segment(gso_skb, features);
215 if (unlikely(IS_ERR_OR_NULL(segs))) {
216 if (copy_dtor)
217 gso_skb->destructor = sock_wfree;
218 return segs;
219 }
220
221 /* GSO partial and frag_list segmentation only requires splitting
222 * the frame into an MSS multiple and possibly a remainder, both
223 * cases return a GSO skb. So update the mss now.
224 */
225 if (skb_is_gso(segs))
226 mss *= skb_shinfo(segs)->gso_segs;
227
228 seg = segs;
229 uh = udp_hdr(seg);
230
231 /* compute checksum adjustment based on old length versus new */
232 newlen = htons(sizeof(*uh) + mss);
233 check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
234
235 for (;;) {
236 if (copy_dtor) {
237 seg->destructor = sock_wfree;
238 seg->sk = sk;
239 sum_truesize += seg->truesize;
240 }
241
242 if (!seg->next)
243 break;
244
245 uh->len = newlen;
246 uh->check = check;
247
248 if (seg->ip_summed == CHECKSUM_PARTIAL)
249 gso_reset_checksum(seg, ~check);
250 else
251 uh->check = gso_make_checksum(seg, ~check) ? :
252 CSUM_MANGLED_0;
253
254 seg = seg->next;
255 uh = udp_hdr(seg);
256 }
257
258 /* last packet can be partial gso_size, account for that in checksum */
259 newlen = htons(skb_tail_pointer(seg) - skb_transport_header(seg) +
260 seg->data_len);
261 check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
262
263 uh->len = newlen;
264 uh->check = check;
265
266 if (seg->ip_summed == CHECKSUM_PARTIAL)
267 gso_reset_checksum(seg, ~check);
268 else
269 uh->check = gso_make_checksum(seg, ~check) ? : CSUM_MANGLED_0;
270
271 /* update refcount for the packet */
272 if (copy_dtor) {
273 int delta = sum_truesize - gso_skb->truesize;
274
275 /* In some pathological cases, delta can be negative.
276 * We need to either use refcount_add() or refcount_sub_and_test()
277 */
278 if (likely(delta >= 0))
279 refcount_add(delta, &sk->sk_wmem_alloc);
280 else
281 WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
282 }
283 return segs;
284}
285EXPORT_SYMBOL_GPL(__udp_gso_segment);
286
287static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
288 netdev_features_t features)
289{
290 struct sk_buff *segs = ERR_PTR(-EINVAL);
291 unsigned int mss;
292 __wsum csum;
293 struct udphdr *uh;
294 struct iphdr *iph;
295
296 if (skb->encapsulation &&
297 (skb_shinfo(skb)->gso_type &
298 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
299 segs = skb_udp_tunnel_segment(skb, features, false);
300 goto out;
301 }
302
303 if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
304 goto out;
305
306 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
307 goto out;
308
309 if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
310 return __udp_gso_segment(skb, features);
311
312 mss = skb_shinfo(skb)->gso_size;
313 if (unlikely(skb->len <= mss))
314 goto out;
315
316 /* Do software UFO. Complete and fill in the UDP checksum as
317 * HW cannot do checksum of UDP packets sent as multiple
318 * IP fragments.
319 */
320
321 uh = udp_hdr(skb);
322 iph = ip_hdr(skb);
323
324 uh->check = 0;
325 csum = skb_checksum(skb, 0, skb->len, 0);
326 uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
327 if (uh->check == 0)
328 uh->check = CSUM_MANGLED_0;
329
330 skb->ip_summed = CHECKSUM_UNNECESSARY;
331
332 /* If there is no outer header we can fake a checksum offload
333 * due to the fact that we have already done the checksum in
334 * software prior to segmenting the frame.
335 */
336 if (!skb->encap_hdr_csum)
337 features |= NETIF_F_HW_CSUM;
338
339 /* Fragment the skb. IP headers of the fragments are updated in
340 * inet_gso_segment()
341 */
342 segs = skb_segment(skb, features);
343out:
344 return segs;
345}
346
347#define UDP_GRO_CNT_MAX 64
348static struct sk_buff *udp_gro_receive_segment(struct list_head *head,
349 struct sk_buff *skb)
350{
351 struct udphdr *uh = udp_hdr(skb);
352 struct sk_buff *pp = NULL;
353 struct udphdr *uh2;
354 struct sk_buff *p;
355
356 /* requires non zero csum, for symmetry with GSO */
357 if (!uh->check) {
358 NAPI_GRO_CB(skb)->flush = 1;
359 return NULL;
360 }
361
362 /* pull encapsulating udp header */
363 skb_gro_pull(skb, sizeof(struct udphdr));
364 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
365
366 list_for_each_entry(p, head, list) {
367 if (!NAPI_GRO_CB(p)->same_flow)
368 continue;
369
370 uh2 = udp_hdr(p);
371
372 /* Match ports only, as csum is always non zero */
373 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source)) {
374 NAPI_GRO_CB(p)->same_flow = 0;
375 continue;
376 }
377
378 /* Terminate the flow on len mismatch or if it grow "too much".
379 * Under small packet flood GRO count could elsewhere grow a lot
380 * leading to execessive truesize values
381 */
382 if (!skb_gro_receive(p, skb) &&
383 NAPI_GRO_CB(p)->count >= UDP_GRO_CNT_MAX)
384 pp = p;
385 else if (uh->len != uh2->len)
386 pp = p;
387
388 return pp;
389 }
390
391 /* mismatch, but we never need to flush */
392 return NULL;
393}
394
395INDIRECT_CALLABLE_DECLARE(struct sock *udp6_lib_lookup_skb(struct sk_buff *skb,
396 __be16 sport, __be16 dport));
397struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
398 struct udphdr *uh, udp_lookup_t lookup)
399{
400 struct sk_buff *pp = NULL;
401 struct sk_buff *p;
402 struct udphdr *uh2;
403 unsigned int off = skb_gro_offset(skb);
404 int flush = 1;
405 struct sock *sk;
406
407 rcu_read_lock();
408 sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb,
409 udp4_lib_lookup_skb, skb, uh->source, uh->dest);
410 if (!sk)
411 goto out_unlock;
412
413 if (udp_sk(sk)->gro_enabled) {
414 pp = call_gro_receive(udp_gro_receive_segment, head, skb);
415 rcu_read_unlock();
416 return pp;
417 }
418
419 if (NAPI_GRO_CB(skb)->encap_mark ||
420 (skb->ip_summed != CHECKSUM_PARTIAL &&
421 NAPI_GRO_CB(skb)->csum_cnt == 0 &&
422 !NAPI_GRO_CB(skb)->csum_valid) ||
423 !udp_sk(sk)->gro_receive)
424 goto out_unlock;
425
426 /* mark that this skb passed once through the tunnel gro layer */
427 NAPI_GRO_CB(skb)->encap_mark = 1;
428
429 flush = 0;
430
431 list_for_each_entry(p, head, list) {
432 if (!NAPI_GRO_CB(p)->same_flow)
433 continue;
434
435 uh2 = (struct udphdr *)(p->data + off);
436
437 /* Match ports and either checksums are either both zero
438 * or nonzero.
439 */
440 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
441 (!uh->check ^ !uh2->check)) {
442 NAPI_GRO_CB(p)->same_flow = 0;
443 continue;
444 }
445 }
446
447 skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
448 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
449 pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb);
450
451out_unlock:
452 rcu_read_unlock();
453 skb_gro_flush_final(skb, pp, flush);
454 return pp;
455}
456EXPORT_SYMBOL(udp_gro_receive);
457
458INDIRECT_CALLABLE_SCOPE
459struct sk_buff *udp4_gro_receive(struct list_head *head, struct sk_buff *skb)
460{
461 struct udphdr *uh = udp_gro_udphdr(skb);
462
463 if (unlikely(!uh) || !static_branch_unlikely(&udp_encap_needed_key))
464 goto flush;
465
466 /* Don't bother verifying checksum if we're going to flush anyway. */
467 if (NAPI_GRO_CB(skb)->flush)
468 goto skip;
469
470 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
471 inet_gro_compute_pseudo))
472 goto flush;
473 else if (uh->check)
474 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
475 inet_gro_compute_pseudo);
476skip:
477 NAPI_GRO_CB(skb)->is_ipv6 = 0;
478 return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb);
479
480flush:
481 NAPI_GRO_CB(skb)->flush = 1;
482 return NULL;
483}
484
485static int udp_gro_complete_segment(struct sk_buff *skb)
486{
487 struct udphdr *uh = udp_hdr(skb);
488
489 skb->csum_start = (unsigned char *)uh - skb->head;
490 skb->csum_offset = offsetof(struct udphdr, check);
491 skb->ip_summed = CHECKSUM_PARTIAL;
492
493 skb_shinfo(skb)->gso_segs = NAPI_GRO_CB(skb)->count;
494 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_L4;
495 return 0;
496}
497
498int udp_gro_complete(struct sk_buff *skb, int nhoff,
499 udp_lookup_t lookup)
500{
501 __be16 newlen = htons(skb->len - nhoff);
502 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
503 int err = -ENOSYS;
504 struct sock *sk;
505
506 uh->len = newlen;
507
508 rcu_read_lock();
509 sk = INDIRECT_CALL_INET(lookup, udp6_lib_lookup_skb,
510 udp4_lib_lookup_skb, skb, uh->source, uh->dest);
511 if (sk && udp_sk(sk)->gro_enabled) {
512 err = udp_gro_complete_segment(skb);
513 } else if (sk && udp_sk(sk)->gro_complete) {
514 skb_shinfo(skb)->gso_type = uh->check ? SKB_GSO_UDP_TUNNEL_CSUM
515 : SKB_GSO_UDP_TUNNEL;
516
517 /* Set encapsulation before calling into inner gro_complete()
518 * functions to make them set up the inner offsets.
519 */
520 skb->encapsulation = 1;
521 err = udp_sk(sk)->gro_complete(sk, skb,
522 nhoff + sizeof(struct udphdr));
523 }
524 rcu_read_unlock();
525
526 if (skb->remcsum_offload)
527 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
528
529 return err;
530}
531EXPORT_SYMBOL(udp_gro_complete);
532
533INDIRECT_CALLABLE_SCOPE int udp4_gro_complete(struct sk_buff *skb, int nhoff)
534{
535 const struct iphdr *iph = ip_hdr(skb);
536 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
537
538 if (uh->check)
539 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
540 iph->daddr, 0);
541
542 return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
543}
544
545static const struct net_offload udpv4_offload = {
546 .callbacks = {
547 .gso_segment = udp4_ufo_fragment,
548 .gro_receive = udp4_gro_receive,
549 .gro_complete = udp4_gro_complete,
550 },
551};
552
553int __init udpv4_offload_init(void)
554{
555 return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
556}
557