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Linux/net/ipv6/ip6_offload.c

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  1 /*
  2  *      IPV6 GSO/GRO offload support
  3  *      Linux INET6 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 
 11 #include <linux/kernel.h>
 12 #include <linux/socket.h>
 13 #include <linux/netdevice.h>
 14 #include <linux/skbuff.h>
 15 #include <linux/printk.h>
 16 
 17 #include <net/protocol.h>
 18 #include <net/ipv6.h>
 19 #include <net/inet_common.h>
 20 
 21 #include "ip6_offload.h"
 22 
 23 static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
 24 {
 25         const struct net_offload *ops = NULL;
 26 
 27         for (;;) {
 28                 struct ipv6_opt_hdr *opth;
 29                 int len;
 30 
 31                 if (proto != NEXTHDR_HOP) {
 32                         ops = rcu_dereference(inet6_offloads[proto]);
 33 
 34                         if (unlikely(!ops))
 35                                 break;
 36 
 37                         if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
 38                                 break;
 39                 }
 40 
 41                 if (unlikely(!pskb_may_pull(skb, 8)))
 42                         break;
 43 
 44                 opth = (void *)skb->data;
 45                 len = ipv6_optlen(opth);
 46 
 47                 if (unlikely(!pskb_may_pull(skb, len)))
 48                         break;
 49 
 50                 opth = (void *)skb->data;
 51                 proto = opth->nexthdr;
 52                 __skb_pull(skb, len);
 53         }
 54 
 55         return proto;
 56 }
 57 
 58 static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
 59         netdev_features_t features)
 60 {
 61         struct sk_buff *segs = ERR_PTR(-EINVAL);
 62         struct ipv6hdr *ipv6h;
 63         const struct net_offload *ops;
 64         int proto;
 65         struct frag_hdr *fptr;
 66         unsigned int payload_len;
 67         u8 *prevhdr;
 68         int offset = 0;
 69         bool encap, udpfrag;
 70         int nhoff;
 71         bool gso_partial;
 72 
 73         skb_reset_network_header(skb);
 74         nhoff = skb_network_header(skb) - skb_mac_header(skb);
 75         if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
 76                 goto out;
 77 
 78         encap = SKB_GSO_CB(skb)->encap_level > 0;
 79         if (encap)
 80                 features &= skb->dev->hw_enc_features;
 81         SKB_GSO_CB(skb)->encap_level += sizeof(*ipv6h);
 82 
 83         ipv6h = ipv6_hdr(skb);
 84         __skb_pull(skb, sizeof(*ipv6h));
 85         segs = ERR_PTR(-EPROTONOSUPPORT);
 86 
 87         proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
 88 
 89         if (skb->encapsulation &&
 90             skb_shinfo(skb)->gso_type & (SKB_GSO_IPXIP4 | SKB_GSO_IPXIP6))
 91                 udpfrag = proto == IPPROTO_UDP && encap;
 92         else
 93                 udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
 94 
 95         ops = rcu_dereference(inet6_offloads[proto]);
 96         if (likely(ops && ops->callbacks.gso_segment)) {
 97                 skb_reset_transport_header(skb);
 98                 segs = ops->callbacks.gso_segment(skb, features);
 99         }
100 
101         if (IS_ERR_OR_NULL(segs))
102                 goto out;
103 
104         gso_partial = !!(skb_shinfo(segs)->gso_type & SKB_GSO_PARTIAL);
105 
106         for (skb = segs; skb; skb = skb->next) {
107                 ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
108                 if (gso_partial && skb_is_gso(skb))
109                         payload_len = skb_shinfo(skb)->gso_size +
110                                       SKB_GSO_CB(skb)->data_offset +
111                                       skb->head - (unsigned char *)(ipv6h + 1);
112                 else
113                         payload_len = skb->len - nhoff - sizeof(*ipv6h);
114                 ipv6h->payload_len = htons(payload_len);
115                 skb->network_header = (u8 *)ipv6h - skb->head;
116 
117                 if (udpfrag) {
118                         int err = ip6_find_1stfragopt(skb, &prevhdr);
119                         if (err < 0) {
120                                 kfree_skb_list(segs);
121                                 return ERR_PTR(err);
122                         }
123                         fptr = (struct frag_hdr *)((u8 *)ipv6h + err);
124                         fptr->frag_off = htons(offset);
125                         if (skb->next)
126                                 fptr->frag_off |= htons(IP6_MF);
127                         offset += (ntohs(ipv6h->payload_len) -
128                                    sizeof(struct frag_hdr));
129                 }
130                 if (encap)
131                         skb_reset_inner_headers(skb);
132         }
133 
134 out:
135         return segs;
136 }
137 
138 /* Return the total length of all the extension hdrs, following the same
139  * logic in ipv6_gso_pull_exthdrs() when parsing ext-hdrs.
140  */
141 static int ipv6_exthdrs_len(struct ipv6hdr *iph,
142                             const struct net_offload **opps)
143 {
144         struct ipv6_opt_hdr *opth = (void *)iph;
145         int len = 0, proto, optlen = sizeof(*iph);
146 
147         proto = iph->nexthdr;
148         for (;;) {
149                 if (proto != NEXTHDR_HOP) {
150                         *opps = rcu_dereference(inet6_offloads[proto]);
151                         if (unlikely(!(*opps)))
152                                 break;
153                         if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
154                                 break;
155                 }
156                 opth = (void *)opth + optlen;
157                 optlen = ipv6_optlen(opth);
158                 len += optlen;
159                 proto = opth->nexthdr;
160         }
161         return len;
162 }
163 
164 static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
165                                          struct sk_buff *skb)
166 {
167         const struct net_offload *ops;
168         struct sk_buff **pp = NULL;
169         struct sk_buff *p;
170         struct ipv6hdr *iph;
171         unsigned int nlen;
172         unsigned int hlen;
173         unsigned int off;
174         u16 flush = 1;
175         int proto;
176 
177         off = skb_gro_offset(skb);
178         hlen = off + sizeof(*iph);
179         iph = skb_gro_header_fast(skb, off);
180         if (skb_gro_header_hard(skb, hlen)) {
181                 iph = skb_gro_header_slow(skb, hlen, off);
182                 if (unlikely(!iph))
183                         goto out;
184         }
185 
186         skb_set_network_header(skb, off);
187         skb_gro_pull(skb, sizeof(*iph));
188         skb_set_transport_header(skb, skb_gro_offset(skb));
189 
190         flush += ntohs(iph->payload_len) != skb_gro_len(skb);
191 
192         rcu_read_lock();
193         proto = iph->nexthdr;
194         ops = rcu_dereference(inet6_offloads[proto]);
195         if (!ops || !ops->callbacks.gro_receive) {
196                 __pskb_pull(skb, skb_gro_offset(skb));
197                 skb_gro_frag0_invalidate(skb);
198                 proto = ipv6_gso_pull_exthdrs(skb, proto);
199                 skb_gro_pull(skb, -skb_transport_offset(skb));
200                 skb_reset_transport_header(skb);
201                 __skb_push(skb, skb_gro_offset(skb));
202 
203                 ops = rcu_dereference(inet6_offloads[proto]);
204                 if (!ops || !ops->callbacks.gro_receive)
205                         goto out_unlock;
206 
207                 iph = ipv6_hdr(skb);
208         }
209 
210         NAPI_GRO_CB(skb)->proto = proto;
211 
212         flush--;
213         nlen = skb_network_header_len(skb);
214 
215         for (p = *head; p; p = p->next) {
216                 const struct ipv6hdr *iph2;
217                 __be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */
218 
219                 if (!NAPI_GRO_CB(p)->same_flow)
220                         continue;
221 
222                 iph2 = (struct ipv6hdr *)(p->data + off);
223                 first_word = *(__be32 *)iph ^ *(__be32 *)iph2;
224 
225                 /* All fields must match except length and Traffic Class.
226                  * XXX skbs on the gro_list have all been parsed and pulled
227                  * already so we don't need to compare nlen
228                  * (nlen != (sizeof(*iph2) + ipv6_exthdrs_len(iph2, &ops)))
229                  * memcmp() alone below is suffcient, right?
230                  */
231                  if ((first_word & htonl(0xF00FFFFF)) ||
232                     memcmp(&iph->nexthdr, &iph2->nexthdr,
233                            nlen - offsetof(struct ipv6hdr, nexthdr))) {
234                         NAPI_GRO_CB(p)->same_flow = 0;
235                         continue;
236                 }
237                 /* flush if Traffic Class fields are different */
238                 NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
239                 NAPI_GRO_CB(p)->flush |= flush;
240 
241                 /* If the previous IP ID value was based on an atomic
242                  * datagram we can overwrite the value and ignore it.
243                  */
244                 if (NAPI_GRO_CB(skb)->is_atomic)
245                         NAPI_GRO_CB(p)->flush_id = 0;
246         }
247 
248         NAPI_GRO_CB(skb)->is_atomic = true;
249         NAPI_GRO_CB(skb)->flush |= flush;
250 
251         skb_gro_postpull_rcsum(skb, iph, nlen);
252 
253         pp = call_gro_receive(ops->callbacks.gro_receive, head, skb);
254 
255 out_unlock:
256         rcu_read_unlock();
257 
258 out:
259         skb_gro_flush_final(skb, pp, flush);
260 
261         return pp;
262 }
263 
264 static struct sk_buff **sit_ip6ip6_gro_receive(struct sk_buff **head,
265                                                struct sk_buff *skb)
266 {
267         /* Common GRO receive for SIT and IP6IP6 */
268 
269         if (NAPI_GRO_CB(skb)->encap_mark) {
270                 NAPI_GRO_CB(skb)->flush = 1;
271                 return NULL;
272         }
273 
274         NAPI_GRO_CB(skb)->encap_mark = 1;
275 
276         return ipv6_gro_receive(head, skb);
277 }
278 
279 static struct sk_buff **ip4ip6_gro_receive(struct sk_buff **head,
280                                            struct sk_buff *skb)
281 {
282         /* Common GRO receive for SIT and IP6IP6 */
283 
284         if (NAPI_GRO_CB(skb)->encap_mark) {
285                 NAPI_GRO_CB(skb)->flush = 1;
286                 return NULL;
287         }
288 
289         NAPI_GRO_CB(skb)->encap_mark = 1;
290 
291         return inet_gro_receive(head, skb);
292 }
293 
294 static int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
295 {
296         const struct net_offload *ops;
297         struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff);
298         int err = -ENOSYS;
299 
300         if (skb->encapsulation) {
301                 skb_set_inner_protocol(skb, cpu_to_be16(ETH_P_IPV6));
302                 skb_set_inner_network_header(skb, nhoff);
303         }
304 
305         iph->payload_len = htons(skb->len - nhoff - sizeof(*iph));
306 
307         rcu_read_lock();
308 
309         nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
310         if (WARN_ON(!ops || !ops->callbacks.gro_complete))
311                 goto out_unlock;
312 
313         err = ops->callbacks.gro_complete(skb, nhoff);
314 
315 out_unlock:
316         rcu_read_unlock();
317 
318         return err;
319 }
320 
321 static int sit_gro_complete(struct sk_buff *skb, int nhoff)
322 {
323         skb->encapsulation = 1;
324         skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP4;
325         return ipv6_gro_complete(skb, nhoff);
326 }
327 
328 static int ip6ip6_gro_complete(struct sk_buff *skb, int nhoff)
329 {
330         skb->encapsulation = 1;
331         skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP6;
332         return ipv6_gro_complete(skb, nhoff);
333 }
334 
335 static int ip4ip6_gro_complete(struct sk_buff *skb, int nhoff)
336 {
337         skb->encapsulation = 1;
338         skb_shinfo(skb)->gso_type |= SKB_GSO_IPXIP6;
339         return inet_gro_complete(skb, nhoff);
340 }
341 
342 static struct packet_offload ipv6_packet_offload __read_mostly = {
343         .type = cpu_to_be16(ETH_P_IPV6),
344         .callbacks = {
345                 .gso_segment = ipv6_gso_segment,
346                 .gro_receive = ipv6_gro_receive,
347                 .gro_complete = ipv6_gro_complete,
348         },
349 };
350 
351 static const struct net_offload sit_offload = {
352         .callbacks = {
353                 .gso_segment    = ipv6_gso_segment,
354                 .gro_receive    = sit_ip6ip6_gro_receive,
355                 .gro_complete   = sit_gro_complete,
356         },
357 };
358 
359 static const struct net_offload ip4ip6_offload = {
360         .callbacks = {
361                 .gso_segment    = inet_gso_segment,
362                 .gro_receive    = ip4ip6_gro_receive,
363                 .gro_complete   = ip4ip6_gro_complete,
364         },
365 };
366 
367 static const struct net_offload ip6ip6_offload = {
368         .callbacks = {
369                 .gso_segment    = ipv6_gso_segment,
370                 .gro_receive    = sit_ip6ip6_gro_receive,
371                 .gro_complete   = ip6ip6_gro_complete,
372         },
373 };
374 static int __init ipv6_offload_init(void)
375 {
376 
377         if (tcpv6_offload_init() < 0)
378                 pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
379         if (ipv6_exthdrs_offload_init() < 0)
380                 pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);
381 
382         dev_add_offload(&ipv6_packet_offload);
383 
384         inet_add_offload(&sit_offload, IPPROTO_IPV6);
385         inet6_add_offload(&ip6ip6_offload, IPPROTO_IPV6);
386         inet6_add_offload(&ip4ip6_offload, IPPROTO_IPIP);
387 
388         return 0;
389 }
390 
391 fs_initcall(ipv6_offload_init);
392 

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