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
__skb_udp_tunnel_segment(struct sk_buff * skb,netdev_features_t features,struct sk_buff * (* gso_inner_segment)(struct sk_buff * skb,netdev_features_t features),__be16 new_protocol,bool is_ipv6)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, ufo, 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 ufo = !!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP);
65
66 need_ipsec = skb_dst(skb) && dst_xfrm(skb_dst(skb));
67 /* Try to offload checksum if possible */
68 offload_csum = !!(need_csum &&
69 !need_ipsec &&
70 (skb->dev->features &
71 (is_ipv6 ? (NETIF_F_HW_CSUM | NETIF_F_IPV6_CSUM) :
72 (NETIF_F_HW_CSUM | NETIF_F_IP_CSUM))));
73
74 features &= skb->dev->hw_enc_features;
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 || ufo) {
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
skb_udp_tunnel_segment(struct sk_buff * skb,netdev_features_t features,bool is_ipv6)153 struct sk_buff *skb_udp_tunnel_segment(struct sk_buff *skb,
154 netdev_features_t features,
155 bool is_ipv6)
156 {
157 __be16 protocol = skb->protocol;
158 const struct net_offload **offloads;
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
udp4_ufo_fragment(struct sk_buff * skb,netdev_features_t features)192 static struct sk_buff *udp4_ufo_fragment(struct sk_buff *skb,
193 netdev_features_t features)
194 {
195 struct sk_buff *segs = ERR_PTR(-EINVAL);
196 unsigned int mss;
197 __wsum csum;
198 struct udphdr *uh;
199 struct iphdr *iph;
200
201 if (skb->encapsulation &&
202 (skb_shinfo(skb)->gso_type &
203 (SKB_GSO_UDP_TUNNEL|SKB_GSO_UDP_TUNNEL_CSUM))) {
204 segs = skb_udp_tunnel_segment(skb, features, false);
205 goto out;
206 }
207
208 if (!(skb_shinfo(skb)->gso_type & SKB_GSO_UDP))
209 goto out;
210
211 if (!pskb_may_pull(skb, sizeof(struct udphdr)))
212 goto out;
213
214 mss = skb_shinfo(skb)->gso_size;
215 if (unlikely(skb->len <= mss))
216 goto out;
217
218 if (skb_gso_ok(skb, features | NETIF_F_GSO_ROBUST)) {
219 /* Packet is from an untrusted source, reset gso_segs. */
220
221 skb_shinfo(skb)->gso_segs = DIV_ROUND_UP(skb->len, mss);
222
223 segs = NULL;
224 goto out;
225 }
226
227 /* Do software UFO. Complete and fill in the UDP checksum as
228 * HW cannot do checksum of UDP packets sent as multiple
229 * IP fragments.
230 */
231
232 uh = udp_hdr(skb);
233 iph = ip_hdr(skb);
234
235 uh->check = 0;
236 csum = skb_checksum(skb, 0, skb->len, 0);
237 uh->check = udp_v4_check(skb->len, iph->saddr, iph->daddr, csum);
238 if (uh->check == 0)
239 uh->check = CSUM_MANGLED_0;
240
241 skb->ip_summed = CHECKSUM_UNNECESSARY;
242
243 /* If there is no outer header we can fake a checksum offload
244 * due to the fact that we have already done the checksum in
245 * software prior to segmenting the frame.
246 */
247 if (!skb->encap_hdr_csum)
248 features |= NETIF_F_HW_CSUM;
249
250 /* Fragment the skb. IP headers of the fragments are updated in
251 * inet_gso_segment()
252 */
253 segs = skb_segment(skb, features);
254 out:
255 return segs;
256 }
257
udp_gro_receive(struct sk_buff ** head,struct sk_buff * skb,struct udphdr * uh,udp_lookup_t lookup)258 struct sk_buff **udp_gro_receive(struct sk_buff **head, struct sk_buff *skb,
259 struct udphdr *uh, udp_lookup_t lookup)
260 {
261 struct sk_buff *p, **pp = NULL;
262 struct udphdr *uh2;
263 unsigned int off = skb_gro_offset(skb);
264 int flush = 1;
265 struct sock *sk;
266
267 if (NAPI_GRO_CB(skb)->encap_mark ||
268 (skb->ip_summed != CHECKSUM_PARTIAL &&
269 NAPI_GRO_CB(skb)->csum_cnt == 0 &&
270 !NAPI_GRO_CB(skb)->csum_valid))
271 goto out;
272
273 /* mark that this skb passed once through the tunnel gro layer */
274 NAPI_GRO_CB(skb)->encap_mark = 1;
275
276 rcu_read_lock();
277 sk = (*lookup)(skb, uh->source, uh->dest);
278
279 if (sk && udp_sk(sk)->gro_receive)
280 goto unflush;
281 goto out_unlock;
282
283 unflush:
284 flush = 0;
285
286 for (p = *head; p; p = p->next) {
287 if (!NAPI_GRO_CB(p)->same_flow)
288 continue;
289
290 uh2 = (struct udphdr *)(p->data + off);
291
292 /* Match ports and either checksums are either both zero
293 * or nonzero.
294 */
295 if ((*(u32 *)&uh->source != *(u32 *)&uh2->source) ||
296 (!uh->check ^ !uh2->check)) {
297 NAPI_GRO_CB(p)->same_flow = 0;
298 continue;
299 }
300 }
301
302 skb_gro_pull(skb, sizeof(struct udphdr)); /* pull encapsulating udp header */
303 skb_gro_postpull_rcsum(skb, uh, sizeof(struct udphdr));
304 pp = call_gro_receive_sk(udp_sk(sk)->gro_receive, sk, head, skb);
305
306 out_unlock:
307 rcu_read_unlock();
308 out:
309 NAPI_GRO_CB(skb)->flush |= flush;
310 return pp;
311 }
312 EXPORT_SYMBOL(udp_gro_receive);
313
udp4_gro_receive(struct sk_buff ** head,struct sk_buff * skb)314 static struct sk_buff **udp4_gro_receive(struct sk_buff **head,
315 struct sk_buff *skb)
316 {
317 struct udphdr *uh = udp_gro_udphdr(skb);
318
319 if (unlikely(!uh))
320 goto flush;
321
322 /* Don't bother verifying checksum if we're going to flush anyway. */
323 if (NAPI_GRO_CB(skb)->flush)
324 goto skip;
325
326 if (skb_gro_checksum_validate_zero_check(skb, IPPROTO_UDP, uh->check,
327 inet_gro_compute_pseudo))
328 goto flush;
329 else if (uh->check)
330 skb_gro_checksum_try_convert(skb, IPPROTO_UDP, uh->check,
331 inet_gro_compute_pseudo);
332 skip:
333 NAPI_GRO_CB(skb)->is_ipv6 = 0;
334 return udp_gro_receive(head, skb, uh, udp4_lib_lookup_skb);
335
336 flush:
337 NAPI_GRO_CB(skb)->flush = 1;
338 return NULL;
339 }
340
udp_gro_complete(struct sk_buff * skb,int nhoff,udp_lookup_t lookup)341 int udp_gro_complete(struct sk_buff *skb, int nhoff,
342 udp_lookup_t lookup)
343 {
344 __be16 newlen = htons(skb->len - nhoff);
345 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
346 int err = -ENOSYS;
347 struct sock *sk;
348
349 uh->len = newlen;
350
351 /* Set encapsulation before calling into inner gro_complete() functions
352 * to make them set up the inner offsets.
353 */
354 skb->encapsulation = 1;
355
356 rcu_read_lock();
357 sk = (*lookup)(skb, uh->source, uh->dest);
358 if (sk && udp_sk(sk)->gro_complete)
359 err = udp_sk(sk)->gro_complete(sk, skb,
360 nhoff + sizeof(struct udphdr));
361 rcu_read_unlock();
362
363 if (skb->remcsum_offload)
364 skb_shinfo(skb)->gso_type |= SKB_GSO_TUNNEL_REMCSUM;
365
366 return err;
367 }
368 EXPORT_SYMBOL(udp_gro_complete);
369
udp4_gro_complete(struct sk_buff * skb,int nhoff)370 static int udp4_gro_complete(struct sk_buff *skb, int nhoff)
371 {
372 const struct iphdr *iph = ip_hdr(skb);
373 struct udphdr *uh = (struct udphdr *)(skb->data + nhoff);
374
375 if (uh->check) {
376 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL_CSUM;
377 uh->check = ~udp_v4_check(skb->len - nhoff, iph->saddr,
378 iph->daddr, 0);
379 } else {
380 skb_shinfo(skb)->gso_type |= SKB_GSO_UDP_TUNNEL;
381 }
382
383 return udp_gro_complete(skb, nhoff, udp4_lib_lookup_skb);
384 }
385
386 static const struct net_offload udpv4_offload = {
387 .callbacks = {
388 .gso_segment = udp4_ufo_fragment,
389 .gro_receive = udp4_gro_receive,
390 .gro_complete = udp4_gro_complete,
391 },
392 };
393
udpv4_offload_init(void)394 int __init udpv4_offload_init(void)
395 {
396 return inet_add_offload(&udpv4_offload, IPPROTO_UDP);
397 }
398