net/ipv6/ip6_offload.c

   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         rcu_read_lock();
  70         ops = rcu_dereference(inet6_offloads[
  71                 ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr)]);
  72
  73         if (likely(ops && ops->callbacks.gso_send_check)) {
  74                 skb_reset_transport_header(skb);
  75                 err = ops->callbacks.gso_send_check(skb);
  76         }
  77         rcu_read_unlock();
  78
  79 out:
  80         return err;
  81 }
  82
  83 static struct sk_buff *ipv6_gso_segment(struct sk_buff *skb,
  84         netdev_features_t features)
  85 {
  86         struct sk_buff *segs = ERR_PTR(-EINVAL);
  87         struct ipv6hdr *ipv6h;
  88         const struct net_offload *ops;
  89         int proto;
  90         struct frag_hdr *fptr;
  91         unsigned int unfrag_ip6hlen;
  92         u8 *prevhdr;
  93         int offset = 0;
  94
  95         if (!(features & NETIF_F_V6_CSUM))
  96                 features &= ~NETIF_F_SG;
  97
  98         if (unlikely(skb_shinfo(skb)->gso_type &
  99                      ~(SKB_GSO_UDP |
 100                        SKB_GSO_DODGY |
 101                        SKB_GSO_TCP_ECN |
 102                        SKB_GSO_GRE |
 103                        SKB_GSO_TCPV6 |
 104                        0)))
 105                 goto out;
 106
 107         if (unlikely(!pskb_may_pull(skb, sizeof(*ipv6h))))
 108                 goto out;
 109
 110         ipv6h = ipv6_hdr(skb);
 111         __skb_pull(skb, sizeof(*ipv6h));
 112         segs = ERR_PTR(-EPROTONOSUPPORT);
 113
 114         proto = ipv6_gso_pull_exthdrs(skb, ipv6h->nexthdr);
 115         rcu_read_lock();
 116         ops = rcu_dereference(inet6_offloads[proto]);
 117         if (likely(ops && ops->callbacks.gso_segment)) {
 118                 skb_reset_transport_header(skb);
 119                 segs = ops->callbacks.gso_segment(skb, features);
 120         }
 121         rcu_read_unlock();
 122
 123         if (IS_ERR(segs))
 124                 goto out;
 125
 126         for (skb = segs; skb; skb = skb->next) {
 127                 ipv6h = ipv6_hdr(skb);
 128                 ipv6h->payload_len = htons(skb->len - skb->mac_len -
 129                                            sizeof(*ipv6h));
 130                 if (proto == IPPROTO_UDP) {
 131                         unfrag_ip6hlen = ip6_find_1stfragopt(skb, &prevhdr);
 132                         fptr = (struct frag_hdr *)(skb_network_header(skb) +
 133                                 unfrag_ip6hlen);
 134                         fptr->frag_off = htons(offset);
 135                         if (skb->next != NULL)
 136                                 fptr->frag_off |= htons(IP6_MF);
 137                         offset += (ntohs(ipv6h->payload_len) -
 138                                    sizeof(struct frag_hdr));
 139                 }
 140         }
 141
 142 out:
 143         return segs;
 144 }
 145
 146 static struct sk_buff **ipv6_gro_receive(struct sk_buff **head,
 147                                          struct sk_buff *skb)
 148 {
 149         const struct net_offload *ops;
 150         struct sk_buff **pp = NULL;
 151         struct sk_buff *p;
 152         struct ipv6hdr *iph;
 153         unsigned int nlen;
 154         unsigned int hlen;
 155         unsigned int off;
 156         int flush = 1;
 157         int proto;
 158         __wsum csum;
 159
 160         off = skb_gro_offset(skb);
 161         hlen = off + sizeof(*iph);
 162         iph = skb_gro_header_fast(skb, off);
 163         if (skb_gro_header_hard(skb, hlen)) {
 164                 iph = skb_gro_header_slow(skb, hlen, off);
 165                 if (unlikely(!iph))
 166                         goto out;
 167         }
 168
 169         skb_gro_pull(skb, sizeof(*iph));
 170         skb_set_transport_header(skb, skb_gro_offset(skb));
 171
 172         flush += ntohs(iph->payload_len) != skb_gro_len(skb);
 173
 174         rcu_read_lock();
 175         proto = iph->nexthdr;
 176         ops = rcu_dereference(inet6_offloads[proto]);
 177         if (!ops || !ops->callbacks.gro_receive) {
 178                 __pskb_pull(skb, skb_gro_offset(skb));
 179                 proto = ipv6_gso_pull_exthdrs(skb, proto);
 180                 skb_gro_pull(skb, -skb_transport_offset(skb));
 181                 skb_reset_transport_header(skb);
 182                 __skb_push(skb, skb_gro_offset(skb));
 183
 184                 ops = rcu_dereference(inet6_offloads[proto]);
 185                 if (!ops || !ops->callbacks.gro_receive)
 186                         goto out_unlock;
 187
 188                 iph = ipv6_hdr(skb);
 189         }
 190
 191         NAPI_GRO_CB(skb)->proto = proto;
 192
 193         flush--;
 194         nlen = skb_network_header_len(skb);
 195
 196         for (p = *head; p; p = p->next) {
 197                 const struct ipv6hdr *iph2;
 198                 __be32 first_word; /* <Version:4><Traffic_Class:8><Flow_Label:20> */
 199
 200                 if (!NAPI_GRO_CB(p)->same_flow)
 201                         continue;
 202
 203                 iph2 = ipv6_hdr(p);
 204                 first_word = *(__be32 *)iph ^ *(__be32 *)iph2 ;
 205
 206                 /* All fields must match except length and Traffic Class. */
 207                 if (nlen != skb_network_header_len(p) ||
 208                     (first_word & htonl(0xF00FFFFF)) ||
 209                     memcmp(&iph->nexthdr, &iph2->nexthdr,
 210                            nlen - offsetof(struct ipv6hdr, nexthdr))) {
 211                         NAPI_GRO_CB(p)->same_flow = 0;
 212                         continue;
 213                 }
 214                 /* flush if Traffic Class fields are different */
 215                 NAPI_GRO_CB(p)->flush |= !!(first_word & htonl(0x0FF00000));
 216                 NAPI_GRO_CB(p)->flush |= flush;
 217         }
 218
 219         NAPI_GRO_CB(skb)->flush |= flush;
 220
 221         csum = skb->csum;
 222         skb_postpull_rcsum(skb, iph, skb_network_header_len(skb));
 223
 224         pp = ops->callbacks.gro_receive(head, skb);
 225
 226         skb->csum = csum;
 227
 228 out_unlock:
 229         rcu_read_unlock();
 230
 231 out:
 232         NAPI_GRO_CB(skb)->flush |= flush;
 233
 234         return pp;
 235 }
 236
 237 static int ipv6_gro_complete(struct sk_buff *skb)
 238 {
 239         const struct net_offload *ops;
 240         struct ipv6hdr *iph = ipv6_hdr(skb);
 241         int err = -ENOSYS;
 242
 243         iph->payload_len = htons(skb->len - skb_network_offset(skb) -
 244                                  sizeof(*iph));
 245
 246         rcu_read_lock();
 247         ops = rcu_dereference(inet6_offloads[NAPI_GRO_CB(skb)->proto]);
 248         if (WARN_ON(!ops || !ops->callbacks.gro_complete))
 249                 goto out_unlock;
 250
 251         err = ops->callbacks.gro_complete(skb);
 252
 253 out_unlock:
 254         rcu_read_unlock();
 255
 256         return err;
 257 }
 258
 259 static struct packet_offload ipv6_packet_offload __read_mostly = {
 260         .type = cpu_to_be16(ETH_P_IPV6),
 261         .callbacks = {
 262                 .gso_send_check = ipv6_gso_send_check,
 263                 .gso_segment = ipv6_gso_segment,
 264                 .gro_receive = ipv6_gro_receive,
 265                 .gro_complete = ipv6_gro_complete,
 266         },
 267 };
 268
 269 static int __init ipv6_offload_init(void)
 270 {
 271
 272         if (tcpv6_offload_init() < 0)
 273                 pr_crit("%s: Cannot add TCP protocol offload\n", __func__);
 274         if (udp_offload_init() < 0)
 275                 pr_crit("%s: Cannot add UDP protocol offload\n", __func__);
 276         if (ipv6_exthdrs_offload_init() < 0)
 277                 pr_crit("%s: Cannot add EXTHDRS protocol offload\n", __func__);
 278
 279         dev_add_offload(&ipv6_packet_offload);
 280         return 0;
 281 }
 282
 283 fs_initcall(ipv6_offload_init);