GNU Linux-libre 4.19.211-gnu1
[releases.git] / net / ipv4 / udp_offload.c
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
17 static struct sk_buff *__skb_udp_tunnel_segment(struct sk_buff *skb,
18         netdev_features_t features,
19         struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
20                                              netdev_features_t features),
21         __be16 new_protocol, bool is_ipv6)
22 {
23         int tnl_hlen = skb_inner_mac_header(skb) - skb_transport_header(skb);
24         bool remcsum, need_csum, offload_csum, gso_partial;
25         struct sk_buff *segs = ERR_PTR(-EINVAL);
26         struct udphdr *uh = udp_hdr(skb);
27         u16 mac_offset = skb->mac_header;
28         __be16 protocol = skb->protocol;
29         u16 mac_len = skb->mac_len;
30         int udp_offset, outer_hlen;
31         __wsum partial;
32         bool need_ipsec;
33
34         if (unlikely(!pskb_may_pull(skb, tnl_hlen)))
35                 goto out;
36
37         /* Adjust partial header checksum to negate old length.
38          * We cannot rely on the value contained in uh->len as it is
39          * possible that the actual value exceeds the boundaries of the
40          * 16 bit length field due to the header being added outside of an
41          * IP or IPv6 frame that was already limited to 64K - 1.
42          */
43         if (skb_shinfo(skb)->gso_type & SKB_GSO_PARTIAL)
44                 partial = (__force __wsum)uh->len;
45         else
46                 partial = (__force __wsum)htonl(skb->len);
47         partial = csum_sub(csum_unfold(uh->check), partial);
48
49         /* setup inner skb. */
50         skb->encapsulation = 0;
51         SKB_GSO_CB(skb)->encap_level = 0;
52         __skb_pull(skb, tnl_hlen);
53         skb_reset_mac_header(skb);
54         skb_set_network_header(skb, skb_inner_network_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
74         /* The only checksum offload we care about from here on out is the
75          * outer one so strip the existing checksum feature flags and
76          * instead set the flag based on our outer checksum offload value.
77          */
78         if (remcsum) {
79                 features &= ~NETIF_F_CSUM_MASK;
80                 if (!need_csum || offload_csum)
81                         features |= NETIF_F_HW_CSUM;
82         }
83
84         /* segment inner packet. */
85         segs = gso_inner_segment(skb, features);
86         if (IS_ERR_OR_NULL(segs)) {
87                 skb_gso_error_unwind(skb, protocol, tnl_hlen, mac_offset,
88                                      mac_len);
89                 goto out;
90         }
91
92         gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
93
94         outer_hlen = skb_tnl_header_len(skb);
95         udp_offset = outer_hlen - tnl_hlen;
96         skb = segs;
97         do {
98                 unsigned int len;
99
100                 if (remcsum)
101                         skb->ip_summed = CHECKSUM_NONE;
102
103                 /* Set up inner headers if we are offloading inner checksum */
104                 if (skb->ip_summed == CHECKSUM_PARTIAL) {
105                         skb_reset_inner_headers(skb);
106                         skb->encapsulation = 1;
107                 }
108
109                 skb->mac_len = mac_len;
110                 skb->protocol = protocol;
111
112                 __skb_push(skb, outer_hlen);
113                 skb_reset_mac_header(skb);
114                 skb_set_network_header(skb, mac_len);
115                 skb_set_transport_header(skb, udp_offset);
116                 len = skb->len - udp_offset;
117                 uh = udp_hdr(skb);
118
119                 /* If we are only performing partial GSO the inner header
120                  * will be using a length value equal to only one MSS sized
121                  * segment instead of the entire frame.
122                  */
123                 if (gso_partial && skb_is_gso(skb)) {
124                         uh->len = htons(skb_shinfo(skb)->gso_size +
125                                         SKB_GSO_CB(skb)->data_offset +
126                                         skb->head - (unsigned char *)uh);
127                 } else {
128                         uh->len = htons(len);
129                 }
130
131                 if (!need_csum)
132                         continue;
133
134                 uh->check = ~csum_fold(csum_add(partial,
135                                        (__force __wsum)htonl(len)));
136
137                 if (skb->encapsulation || !offload_csum) {
138                         uh->check = gso_make_checksum(skb, ~uh->check);
139                         if (uh->check == 0)
140                                 uh->check = CSUM_MANGLED_0;
141                 } else {
142                         skb->ip_summed = CHECKSUM_PARTIAL;
143                         skb->csum_start = skb_transport_header(skb) - skb->head;
144                         skb->csum_offset = offsetof(struct udphdr, check);
145                 }
146         } while ((skb = skb->next));
147 out:
148         return segs;
149 }
150
151 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
152                                        netdev_features_t features,
153                                        bool is_ipv6)
154 {
155         __be16 protocol = skb->protocol;
156         const struct net_offload **offloads;
157         const struct net_offload *ops;
158         struct sk_buff *segs = ERR_PTR(-EINVAL);
159         struct sk_buff *(*gso_inner_segment)(struct sk_buff *skb,
160                                              netdev_features_t features);
161
162         rcu_read_lock();
163
164         switch (skb->inner_protocol_type) {
165         case ENCAP_TYPE_ETHER:
166                 protocol = skb->inner_protocol;
167                 gso_inner_segment = skb_mac_gso_segment;
168                 break;
169         case ENCAP_TYPE_IPPROTO:
170                 offloads = is_ipv6 ? inet6_offloads : inet_offloads;
171                 ops = rcu_dereference(offloads[skb->inner_ipproto]);
172                 if (!ops || !ops->callbacks.gso_segment)
173                         goto out_unlock;
174                 gso_inner_segment = ops->callbacks.gso_segment;
175                 break;
176         default:
177                 goto out_unlock;
178         }
179
180         segs = __skb_udp_tunnel_segment(skb, features, gso_inner_segment,
181                                         protocol, is_ipv6);
182
183 out_unlock:
184         rcu_read_unlock();
185
186         return segs;
187 }
188 EXPORT_SYMBOL(skb_udp_tunnel_segment);
189
190 struct sk_buff *__udp_gso_segment(struct sk_buff *gso_skb,
191                                   netdev_features_t features)
192 {
193         struct sock *sk = gso_skb->sk;
194         unsigned int sum_truesize = 0;
195         struct sk_buff *segs, *seg;
196         struct udphdr *uh;
197         unsigned int mss;
198         bool copy_dtor;
199         __sum16 check;
200         __be16 newlen;
201
202         mss = skb_shinfo(gso_skb)->gso_size;
203         if (gso_skb->len <= sizeof(*uh) + mss)
204                 return ERR_PTR(-EINVAL);
205
206         skb_pull(gso_skb, sizeof(*uh));
207
208         /* clear destructor to avoid skb_segment assigning it to tail */
209         copy_dtor = gso_skb->destructor == sock_wfree;
210         if (copy_dtor)
211                 gso_skb->destructor = NULL;
212
213         segs = skb_segment(gso_skb, features);
214         if (unlikely(IS_ERR_OR_NULL(segs))) {
215                 if (copy_dtor)
216                         gso_skb->destructor = sock_wfree;
217                 return segs;
218         }
219
220         /* GSO partial and frag_list segmentation only requires splitting
221          * the frame into an MSS multiple and possibly a remainder, both
222          * cases return a GSO skb. So update the mss now.
223          */
224         if (skb_is_gso(segs))
225                 mss *= skb_shinfo(segs)->gso_segs;
226
227         seg = segs;
228         uh = udp_hdr(seg);
229
230         /* preserve TX timestamp flags and TS key for first segment */
231         skb_shinfo(seg)->tskey = skb_shinfo(gso_skb)->tskey;
232         skb_shinfo(seg)->tx_flags |=
233                         (skb_shinfo(gso_skb)->tx_flags & SKBTX_ANY_TSTAMP);
234
235         /* compute checksum adjustment based on old length versus new */
236         newlen = htons(sizeof(*uh) + mss);
237         check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
238
239         for (;;) {
240                 if (copy_dtor) {
241                         seg->destructor = sock_wfree;
242                         seg->sk = sk;
243                         sum_truesize += seg->truesize;
244                 }
245
246                 if (!seg->next)
247                         break;
248
249                 uh->len = newlen;
250                 uh->check = check;
251
252                 if (seg->ip_summed == CHECKSUM_PARTIAL)
253                         gso_reset_checksum(seg, ~check);
254                 else
255                         uh->check = gso_make_checksum(seg, ~check) ? :
256                                     CSUM_MANGLED_0;
257
258                 seg = seg->next;
259                 uh = udp_hdr(seg);
260         }
261
262         /* last packet can be partial gso_size, account for that in checksum */
263         newlen = htons(skb_tail_pointer(seg) - skb_transport_header(seg) +
264                        seg->data_len);
265         check = csum16_add(csum16_sub(uh->check, uh->len), newlen);
266
267         uh->len = newlen;
268         uh->check = check;
269
270         if (seg->ip_summed == CHECKSUM_PARTIAL)
271                 gso_reset_checksum(seg, ~check);
272         else
273                 uh->check = gso_make_checksum(seg, ~check) ? : CSUM_MANGLED_0;
274
275         /* update refcount for the packet */
276         if (copy_dtor) {
277                 int delta = sum_truesize - gso_skb->truesize;
278
279                 /* In some pathological cases, delta can be negative.
280                  * We need to either use refcount_add() or refcount_sub_and_test()
281                  */
282                 if (likely(delta >= 0))
283                         refcount_add(delta, &sk->sk_wmem_alloc);
284                 else
285                         WARN_ON_ONCE(refcount_sub_and_test(-delta, &sk->sk_wmem_alloc));
286         }
287         return segs;
288 }
289 EXPORT_SYMBOL_GPL(__udp_gso_segment);
290
291 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
292                                          netdev_features_t features)
293 {
294         struct sk_buff *segs = ERR_PTR(-EINVAL);
295         unsigned int mss;
296         __wsum csum;
297         struct udphdr *uh;
298         struct iphdr *iph;
299
300         if (skb->encapsulation &&
301             (skb_shinfo(skb)->gso_type &
302              (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
303                 segs = skb_udp_tunnel_segment(skb, features, false);
304                 goto out;
305         }
306
307         if (!(skb_shinfo(skb)->gso_type & (SKB_GSO_UDP | SKB_GSO_UDP_L4)))
308                 goto out;
309
310         if (!pskb_may_pull(skb, sizeof(struct udphdr)))
311                 goto out;
312
313         if (skb_shinfo(skb)->gso_type & SKB_GSO_UDP_L4)
314                 return __udp_gso_segment(skb, features);
315
316         mss = skb_shinfo(skb)->gso_size;
317         if (unlikely(skb->len <= mss))
318                 goto out;
319
320         /* Do software UFO. Complete and fill in the UDP checksum as
321          * HW cannot do checksum of UDP packets sent as multiple
322          * IP fragments.
323          */
324
325         uh = udp_hdr(skb);
326         iph = ip_hdr(skb);
327
328         uh->check = 0;
329         csum = skb_checksum(skb, 0, skb->len, 0);
330         uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
331         if (uh->check == 0)
332                 uh->check = CSUM_MANGLED_0;
333
334         skb->ip_summed = CHECKSUM_UNNECESSARY;
335
336         /* If there is no outer header we can fake a checksum offload
337          * due to the fact that we have already done the checksum in
338          * software prior to segmenting the frame.
339          */
340         if (!skb->encap_hdr_csum)
341                 features |= NETIF_F_HW_CSUM;
342
343         /* Fragment the skb. IP headers of the fragments are updated in
344          * inet_gso_segment()
345          */
346         segs = skb_segment(skb, features);
347 out:
348         return segs;
349 }
350
351 struct sk_buff *udp_gro_receive(struct list_head *head, struct sk_buff *skb,
352                                 struct udphdr *uh, udp_lookup_t lookup)
353 {
354         struct sk_buff *pp = NULL;
355         struct sk_buff *p;
356         struct udphdr *uh2;
357         unsigned int off = skb_gro_offset(skb);
358         int flush = 1;
359         struct sock *sk;
360
361         if (NAPI_GRO_CB(skb)->encap_mark ||
362             (uh->check && skb->ip_summed != CHECKSUM_PARTIAL &&
363              NAPI_GRO_CB(skb)->csum_cnt == 0 &&
364              !NAPI_GRO_CB(skb)->csum_valid))
365                 goto out;
366
367         /* mark that this skb passed once through the tunnel gro layer */
368         NAPI_GRO_CB(skb)->encap_mark = 1;
369
370         rcu_read_lock();
371         sk = (*lookup)(skb, uh->source, uh->dest);
372
373         if (sk && udp_sk(sk)->gro_receive)
374                 goto unflush;
375         goto out_unlock;
376
377 unflush:
378         flush = 0;
379
380         list_for_each_entry(p, head, list) {
381                 if (!NAPI_GRO_CB(p)->same_flow)
382                         continue;
383
384                 uh2 = (struct udphdr   *)(p->data + off);
385
386                 /* Match ports and either checksums are either both zero
387                  * or nonzero.
388                  */
389                 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
390                     (!uh->check ^ !uh2->check)) {
391                         NAPI_GRO_CB(p)->same_flow = 0;
392                         continue;
393                 }
394         }
395
396         skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
397         skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
398         pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb);
399
400 out_unlock:
401         rcu_read_unlock();
402 out:
403         skb_gro_flush_final(skb, pp, flush);
404         return pp;
405 }
406 EXPORT_SYMBOL(udp_gro_receive);
407
408 static struct sk_buff *udp4_gro_receive(struct list_head *head,
409                                         struct sk_buff *skb)
410 {
411         struct udphdr *uh = udp_gro_udphdr(skb);
412
413         if (unlikely(!uh))
414                 goto flush;
415
416         /* Don't bother verifying checksum if we're going to flush anyway. */
417         if (NAPI_GRO_CB(skb)->flush)
418                 goto skip;
419
420         if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
421                                                  inet_gro_compute_pseudo))
422                 goto flush;
423         else if (uh->check)
424                 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
425                                              inet_gro_compute_pseudo);
426 skip:
427         NAPI_GRO_CB(skb)->is_ipv6 = 0;
428         return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb);
429
430 flush:
431         NAPI_GRO_CB(skb)->flush = 1;
432         return NULL;
433 }
434
435 int udp_gro_complete(struct sk_buff *skb, int nhoff,
436                      udp_lookup_t lookup)
437 {
438         __be16 newlen = htons(skb->len - nhoff);
439         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
440         int err = -ENOSYS;
441         struct sock *sk;
442
443         uh->len = newlen;
444
445         /* Set encapsulation before calling into inner gro_complete() functions
446          * to make them set up the inner offsets.
447          */
448         skb->encapsulation = 1;
449
450         rcu_read_lock();
451         sk = (*lookup)(skb, uh->source, uh->dest);
452         if (sk && udp_sk(sk)->gro_complete)
453                 err = udp_sk(sk)->gro_complete(sk, skb,
454                                 nhoff + sizeof(struct udphdr));
455         rcu_read_unlock();
456
457         if (skb->remcsum_offload)
458                 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
459
460         return err;
461 }
462 EXPORT_SYMBOL(udp_gro_complete);
463
464 static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
465 {
466         const struct iphdr *iph = ip_hdr(skb);
467         struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
468
469         if (uh->check) {
470                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
471                 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
472                                           iph->daddr, 0);
473         } else {
474                 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
475         }
476
477         return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
478 }
479
480 static const struct net_offload udpv4_offload = {
481         .callbacks = {
482                 .gso_segment = udp4_ufo_fragment,
483                 .gro_receive  = udp4_gro_receive,
484                 .gro_complete = udp4_gro_complete,
485         },
486 };
487
488 int __init udpv4_offload_init(void)
489 {
490         return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
491 }