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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 
 20 #include "ip6_offload.h"
 21 
 22 static int ipv6_gso_pull_exthdrs(struct sk_buff *skb, int proto)
 23 {
 24         const struct net_offload *ops = NULL;
 25 
 26         for (;;) {
 27                 struct ipv6_opt_hdr *opth;
 28                 int len;
 29 
 30                 if (proto != NEXTHDR_HOP) {
 31                         ops = rcu_dereference(inet6_offloads[proto]);
 32 
 33                         if (unlikely(!ops))
 34                                 break;
 35 
 36                         if (!(ops->flags & INET6_PROTO_GSO_EXTHDR))
 37                                 break;
 38                 }
 39 
 40                 if (unlikely(!pskb_may_pull(skb, 8)))
 41                         break;
 42 
 43                 opth = (void *)skb->data;
 44                 len = ipv6_optlen(opth);
 45 
 46                 if (unlikely(!pskb_may_pull(skb, len)))
 47                         break;
 48 
 49                 proto = opth->nexthdr;
 50                 __skb_pull(skb, len);
 51         }
 52 
 53         return proto;
 54 }
 55 
 56 static int ipv6_gso_send_check(struct sk_buff *skb)
 57 {
 58         const struct ipv6hdr *ipv6h;
 59         const struct net_offload *ops;
 60         int err = -EINVAL;
 61 
 62         if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
 63                 goto out;
 64 
 65         ipv6h = ipv6_hdr(skb);
 66         __skb_pull(skb, sizeof(*ipv6h));
 67         err = -EPROTONOSUPPORT;
 68 
 69         ops = rcu_dereference(inet6_offloads[
 70                 ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr)]);
 71 
 72         if (likely(ops && ops->callbacks.gso_send_check)) {
 73                 skb_reset_transport_header(skb);
 74                 err = ops->callbacks.gso_send_check(skb);
 75         }
 76 
 77 out:
 78         return err;
 79 }
 80 
 81 static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
 82         netdev_features_t features)
 83 {
 84         struct sk_buff *segs = ERR_PTR(-EINVAL);
 85         struct ipv6hdr *ipv6h;
 86         const struct net_offload *ops;
 87         int proto;
 88         struct frag_hdr *fptr;
 89         unsigned int unfrag_ip6hlen;
 90         u8 *prevhdr;
 91         int offset = 0;
 92         bool encap, udpfrag;
 93         int nhoff;
 94 
 95         if (unlikely(skb_shinfo(skb)->gso_type &
 96                      ~(SKB_GSO_UDP |
 97                        SKB_GSO_DODGY |
 98                        SKB_GSO_TCP_ECN |
 99                        SKB_GSO_GRE |
100                        SKB_GSO_GRE_CSUM |
101                        SKB_GSO_IPIP |
102                        SKB_GSO_SIT |
103                        SKB_GSO_UDP_TUNNEL |
104                        SKB_GSO_UDP_TUNNEL_CSUM |
105                        SKB_GSO_MPLS |
106                        SKB_GSO_TCPV6 |
107                        0)))
108                 goto out;
109 
110         skb_reset_network_header(skb);
111         nhoff = skb_network_header(skb) - skb_mac_header(skb);
112         if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
113                 goto out;
114 
115         encap = SKB_GSO_CB(skb)->encap_level > 0;
116         if (encap)
117                 features = skb->dev->hw_enc_features & netif_skb_features(skb);
118         SKB_GSO_CB(skb)->encap_level += sizeof(*ipv6h);
119 
120         ipv6h = ipv6_hdr(skb);
121         __skb_pull(skb, sizeof(*ipv6h));
122         segs = ERR_PTR(-EPROTONOSUPPORT);
123 
124         proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
125 
126         if (skb->encapsulation &&
127             skb_shinfo(skb)->gso_type & (SKB_GSO_SIT|SKB_GSO_IPIP))
128                 udpfrag = proto == IPPROTO_UDP && encap;
129         else
130                 udpfrag = proto == IPPROTO_UDP && !skb->encapsulation;
131 
132         ops = rcu_dereference(inet6_offloads[proto]);
133         if (likely(ops && ops->callbacks.gso_segment)) {
134                 skb_reset_transport_header(skb);
135                 segs = ops->callbacks.gso_segment(skb, features);
136         }
137 
138         if (IS_ERR(segs))
139                 goto out;
140 
141         for (skb = segs; skb; skb = skb->next) {
142                 ipv6h = (struct ipv6hdr *)(skb_mac_header(skb) + nhoff);
143                 ipv6h->payload_len = htons(skb->len - nhoff - sizeof(*ipv6h));
144                 skb->network_header = (u8 *)ipv6h - skb->head;
145 
146                 if (udpfrag) {
147                         unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
148                         fptr = (struct frag_hdr *)((u8 *)ipv6h + unfrag_ip6hlen);
149                         fptr->frag_off = htons(offset);
150                         if (skb->next != NULL)
151                                 fptr->frag_off |= htons(IP6_MF);
152                         offset += (ntohs(ipv6h->payload_len) -
153                                    sizeof(struct frag_hdr));
154                 }
155                 if (encap)
156                         skb_reset_inner_headers(skb);
157         }
158 
159 out:
160         return segs;
161 }
162 
163 /* Return the total length of all the extension hdrs, following the same
164  * logic in ipv6_gso_pull_exthdrs() when parsing ext-hdrs.
165  */
166 static int ipv6_exthdrs_len(struct ipv6hdr *iph,
167                             const struct net_offload **opps)
168 {
169         struct ipv6_opt_hdr *opth = (void *)iph;
170         int len = 0, proto, optlen = sizeof(*iph);
171 
172         proto = iph->nexthdr;
173         for (;;) {
174                 if (proto != NEXTHDR_HOP) {
175                         *opps = rcu_dereference(inet6_offloads[proto]);
176                         if (unlikely(!(*opps)))
177                                 break;
178                         if (!((*opps)->flags & INET6_PROTO_GSO_EXTHDR))
179                                 break;
180                 }
181                 opth = (void *)opth + optlen;
182                 optlen = ipv6_optlen(opth);
183                 len += optlen;
184                 proto = opth->nexthdr;
185         }
186         return len;
187 }
188 
189 static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
190                                          struct sk_buff *skb)
191 {
192         const struct net_offload *ops;
193         struct sk_buff **pp = NULL;
194         struct sk_buff *p;
195         struct ipv6hdr *iph;
196         unsigned int nlen;
197         unsigned int hlen;
198         unsigned int off;
199         u16 flush = 1;
200         int proto;
201 
202         off = skb_gro_offset(skb);
203         hlen = off + sizeof(*iph);
204         iph = skb_gro_header_fast(skb, off);
205         if (skb_gro_header_hard(skb, hlen)) {
206                 iph = skb_gro_header_slow(skb, hlen, off);
207                 if (unlikely(!iph))
208                         goto out;
209         }
210 
211         skb_set_network_header(skb, off);
212         skb_gro_pull(skb, sizeof(*iph));
213         skb_set_transport_header(skb, skb_gro_offset(skb));
214 
215         flush += ntohs(iph->payload_len) != skb_gro_len(skb);
216 
217         rcu_read_lock();
218         proto = iph->nexthdr;
219         ops = rcu_dereference(inet6_offloads[proto]);
220         if (!ops || !ops->callbacks.gro_receive) {
221                 __pskb_pull(skb, skb_gro_offset(skb));
222                 proto = ipv6_gso_pull_exthdrs(skb, proto);
223                 skb_gro_pull(skb, -skb_transport_offset(skb));
224                 skb_reset_transport_header(skb);
225                 __skb_push(skb, skb_gro_offset(skb));
226 
227                 ops = rcu_dereference(inet6_offloads[proto]);
228                 if (!ops || !ops->callbacks.gro_receive)
229                         goto out_unlock;
230 
231                 iph = ipv6_hdr(skb);
232         }
233 
234         NAPI_GRO_CB(skb)->proto = proto;
235 
236         flush--;
237         nlen = skb_network_header_len(skb);
238 
239         for (p = *head; p; p = p->next) {
240                 const struct ipv6hdr *iph2;
241                 __be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */
242 
243                 if (!NAPI_GRO_CB(p)->same_flow)
244                         continue;
245 
246                 iph2 = (struct ipv6hdr *)(p->data + off);
247                 first_word = *(__be32 *)iph ^ *(__be32 *)iph2 ;
248 
249                 /* All fields must match except length and Traffic Class.
250                  * XXX skbs on the gro_list have all been parsed and pulled
251                  * already so we don't need to compare nlen
252                  * (nlen != (sizeof(*iph2) + ipv6_exthdrs_len(iph2, &ops)))
253                  * memcmp() alone below is suffcient, right?
254                  */
255                  if ((first_word & htonl(0xF00FFFFF)) ||
256                     memcmp(&iph->nexthdr, &iph2->nexthdr,
257                            nlen - offsetof(struct ipv6hdr, nexthdr))) {
258                         NAPI_GRO_CB(p)->same_flow = 0;
259                         continue;
260                 }
261                 /* flush if Traffic Class fields are different */
262                 NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
263                 NAPI_GRO_CB(p)->flush |= flush;
264         }
265 
266         NAPI_GRO_CB(skb)->flush |= flush;
267 
268         skb_gro_postpull_rcsum(skb, iph, nlen);
269 
270         pp = ops->callbacks.gro_receive(head, skb);
271 
272 out_unlock:
273         rcu_read_unlock();
274 
275 out:
276         NAPI_GRO_CB(skb)->flush |= flush;
277 
278         return pp;
279 }
280 
281 static int ipv6_gro_complete(struct sk_buff *skb, int nhoff)
282 {
283         const struct net_offload *ops;
284         struct ipv6hdr *iph = (struct ipv6hdr *)(skb->data + nhoff);
285         int err = -ENOSYS;
286 
287         iph->payload_len = htons(skb->len - nhoff - sizeof(*iph));
288 
289         rcu_read_lock();
290 
291         nhoff += sizeof(*iph) + ipv6_exthdrs_len(iph, &ops);
292         if (WARN_ON(!ops || !ops->callbacks.gro_complete))
293                 goto out_unlock;
294 
295         err = ops->callbacks.gro_complete(skb, nhoff);
296 
297 out_unlock:
298         rcu_read_unlock();
299 
300         return err;
301 }
302 
303 static struct packet_offload ipv6_packet_offload __read_mostly = {
304         .type = cpu_to_be16(ETH_P_IPV6),
305         .callbacks = {
306                 .gso_send_check = ipv6_gso_send_check,
307                 .gso_segment = ipv6_gso_segment,
308                 .gro_receive = ipv6_gro_receive,
309                 .gro_complete = ipv6_gro_complete,
310         },
311 };
312 
313 static const struct net_offload sit_offload = {
314         .callbacks = {
315                 .gso_send_check = ipv6_gso_send_check,
316                 .gso_segment    = ipv6_gso_segment,
317         },
318 };
319 
320 static int __init ipv6_offload_init(void)
321 {
322 
323         if (tcpv6_offload_init() < 0)
324                 pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
325         if (udp_offload_init() < 0)
326                 pr_crit("%s: Cannot add UDP protocol offload\n", __func__);
327         if (ipv6_exthdrs_offload_init() < 0)
328                 pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);
329 
330         dev_add_offload(&ipv6_packet_offload);
331 
332         inet_add_offload(&sit_offload, IPPROTO_IPV6);
333 
334         return 0;
335 }
336 
337 fs_initcall(ipv6_offload_init);
338 

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