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