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

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