Pileus Git - ~andy/linux/blob - net/ipv4/gre_offload.c

   1 /*
   2  *      IPV4 GSO/GRO offload support
   3  *      Linux INET 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  *      GRE GSO support
  11  */
  12
  13 #include <linux/skbuff.h>
  14 #include <net/protocol.h>
  15 #include <net/gre.h>
  16
  17 static int gre_gso_send_check(struct sk_buff *skb)
  18 {
  19         if (!skb->encapsulation)
  20                 return -EINVAL;
  21         return 0;
  22 }
  23
  24 static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
  25                                        netdev_features_t features)
  26 {
  27         struct sk_buff *segs = ERR_PTR(-EINVAL);
  28         netdev_features_t enc_features;
  29         int ghl;
  30         struct gre_base_hdr *greh;
  31         u16 mac_offset = skb->mac_header;
  32         int mac_len = skb->mac_len;
  33         __be16 protocol = skb->protocol;
  34         int tnl_hlen;
  35         bool csum;
  36
  37         if (unlikely(skb_shinfo(skb)->gso_type &
  38                                 ~(SKB_GSO_TCPV4 |
  39                                   SKB_GSO_TCPV6 |
  40                                   SKB_GSO_UDP |
  41                                   SKB_GSO_DODGY |
  42                                   SKB_GSO_TCP_ECN |
  43                                   SKB_GSO_GRE |
  44                                   SKB_GSO_IPIP)))
  45                 goto out;
  46
  47         if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
  48                 goto out;
  49
  50         greh = (struct gre_base_hdr *)skb_transport_header(skb);
  51
  52         ghl = skb_inner_network_header(skb) - skb_transport_header(skb);
  53         if (unlikely(ghl < sizeof(*greh)))
  54                 goto out;
  55
  56         csum = !!(greh->flags & GRE_CSUM);
  57
  58         if (unlikely(!pskb_may_pull(skb, ghl)))
  59                 goto out;
  60
  61         /* setup inner skb. */
  62         skb->protocol = greh->protocol;
  63         skb->encapsulation = 0;
  64
  65         __skb_pull(skb, ghl);
  66         skb_reset_mac_header(skb);
  67         skb_set_network_header(skb, skb_inner_network_offset(skb));
  68         skb->mac_len = skb_inner_network_offset(skb);
  69
  70         /* segment inner packet. */
  71         enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
  72         segs = skb_mac_gso_segment(skb, enc_features);
  73         if (!segs || IS_ERR(segs)) {
  74                 skb_gso_error_unwind(skb, protocol, ghl, mac_offset, mac_len);
  75                 goto out;
  76         }
  77
  78         skb = segs;
  79         tnl_hlen = skb_tnl_header_len(skb);
  80         do {
  81                 __skb_push(skb, ghl);
  82                 if (csum) {
  83                         __be32 *pcsum;
  84
  85                         if (skb_has_shared_frag(skb)) {
  86                                 int err;
  87
  88                                 err = __skb_linearize(skb);
  89                                 if (err) {
  90                                         kfree_skb_list(segs);
  91                                         segs = ERR_PTR(err);
  92                                         goto out;
  93                                 }
  94                         }
  95
  96                         greh = (struct gre_base_hdr *)(skb->data);
  97                         pcsum = (__be32 *)(greh + 1);
  98                         *pcsum = 0;
  99                         *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
 100                 }
 101                 __skb_push(skb, tnl_hlen - ghl);
 102
 103                 skb_reset_inner_headers(skb);
 104                 skb->encapsulation = 1;
 105
 106                 skb_reset_mac_header(skb);
 107                 skb_set_network_header(skb, mac_len);
 108                 skb->mac_len = mac_len;
 109                 skb->protocol = protocol;
 110         } while ((skb = skb->next));
 111 out:
 112         return segs;
 113 }
 114
 115 /* Compute the whole skb csum in s/w and store it, then verify GRO csum
 116  * starting from gro_offset.
 117  */
 118 static __sum16 gro_skb_checksum(struct sk_buff *skb)
 119 {
 120         __sum16 sum;
 121
 122         skb->csum = skb_checksum(skb, 0, skb->len, 0);
 123         NAPI_GRO_CB(skb)->csum = csum_sub(skb->csum,
 124                 csum_partial(skb->data, skb_gro_offset(skb), 0));
 125         sum = csum_fold(NAPI_GRO_CB(skb)->csum);
 126         if (unlikely(skb->ip_summed == CHECKSUM_COMPLETE)) {
 127                 if (unlikely(!sum))
 128                         netdev_rx_csum_fault(skb->dev);
 129         } else
 130                 skb->ip_summed = CHECKSUM_COMPLETE;
 131
 132         return sum;
 133 }
 134
 135 static struct sk_buff **gre_gro_receive(struct sk_buff **head,
 136                                         struct sk_buff *skb)
 137 {
 138         struct sk_buff **pp = NULL;
 139         struct sk_buff *p;
 140         const struct gre_base_hdr *greh;
 141         unsigned int hlen, grehlen;
 142         unsigned int off;
 143         int flush = 1;
 144         struct packet_offload *ptype;
 145         __be16 type;
 146
 147         off = skb_gro_offset(skb);
 148         hlen = off + sizeof(*greh);
 149         greh = skb_gro_header_fast(skb, off);
 150         if (skb_gro_header_hard(skb, hlen)) {
 151                 greh = skb_gro_header_slow(skb, hlen, off);
 152                 if (unlikely(!greh))
 153                         goto out;
 154         }
 155
 156         /* Only support version 0 and K (key), C (csum) flags. Note that
 157          * although the support for the S (seq#) flag can be added easily
 158          * for GRO, this is problematic for GSO hence can not be enabled
 159          * here because a GRO pkt may end up in the forwarding path, thus
 160          * requiring GSO support to break it up correctly.
 161          */
 162         if ((greh->flags & ~(GRE_KEY|GRE_CSUM)) != 0)
 163                 goto out;
 164
 165         type = greh->protocol;
 166
 167         rcu_read_lock();
 168         ptype = gro_find_receive_by_type(type);
 169         if (ptype == NULL)
 170                 goto out_unlock;
 171
 172         grehlen = GRE_HEADER_SECTION;
 173
 174         if (greh->flags & GRE_KEY)
 175                 grehlen += GRE_HEADER_SECTION;
 176
 177         if (greh->flags & GRE_CSUM)
 178                 grehlen += GRE_HEADER_SECTION;
 179
 180         hlen = off + grehlen;
 181         if (skb_gro_header_hard(skb, hlen)) {
 182                 greh = skb_gro_header_slow(skb, hlen, off);
 183                 if (unlikely(!greh))
 184                         goto out_unlock;
 185         }
 186         if (greh->flags & GRE_CSUM) { /* Need to verify GRE csum first */
 187                 __sum16 csum = 0;
 188
 189                 if (skb->ip_summed == CHECKSUM_COMPLETE)
 190                         csum = csum_fold(NAPI_GRO_CB(skb)->csum);
 191                 /* Don't trust csum error calculated/reported by h/w */
 192                 if (skb->ip_summed == CHECKSUM_NONE || csum != 0)
 193                         csum = gro_skb_checksum(skb);
 194
 195                 /* GRE CSUM is the 1's complement of the 1's complement sum
 196                  * of the GRE hdr plus payload so it should add up to 0xffff
 197                  * (and 0 after csum_fold()) just like the IPv4 hdr csum.
 198                  */
 199                 if (csum)
 200                         goto out_unlock;
 201         }
 202         flush = 0;
 203
 204         for (p = *head; p; p = p->next) {
 205                 const struct gre_base_hdr *greh2;
 206
 207                 if (!NAPI_GRO_CB(p)->same_flow)
 208                         continue;
 209
 210                 /* The following checks are needed to ensure only pkts
 211                  * from the same tunnel are considered for aggregation.
 212                  * The criteria for "the same tunnel" includes:
 213                  * 1) same version (we only support version 0 here)
 214                  * 2) same protocol (we only support ETH_P_IP for now)
 215                  * 3) same set of flags
 216                  * 4) same key if the key field is present.
 217                  */
 218                 greh2 = (struct gre_base_hdr *)(p->data + off);
 219
 220                 if (greh2->flags != greh->flags ||
 221                     greh2->protocol != greh->protocol) {
 222                         NAPI_GRO_CB(p)->same_flow = 0;
 223                         continue;
 224                 }
 225                 if (greh->flags & GRE_KEY) {
 226                         /* compare keys */
 227                         if (*(__be32 *)(greh2+1) != *(__be32 *)(greh+1)) {
 228                                 NAPI_GRO_CB(p)->same_flow = 0;
 229                                 continue;
 230                         }
 231                 }
 232         }
 233
 234         skb_gro_pull(skb, grehlen);
 235
 236         /* Adjusted NAPI_GRO_CB(skb)->csum after skb_gro_pull()*/
 237         skb_gro_postpull_rcsum(skb, greh, grehlen);
 238
 239         pp = ptype->callbacks.gro_receive(head, skb);
 240
 241 out_unlock:
 242         rcu_read_unlock();
 243 out:
 244         NAPI_GRO_CB(skb)->flush |= flush;
 245
 246         return pp;
 247 }
 248
 249 static int gre_gro_complete(struct sk_buff *skb, int nhoff)
 250 {
 251         struct gre_base_hdr *greh = (struct gre_base_hdr *)(skb->data + nhoff);
 252         struct packet_offload *ptype;
 253         unsigned int grehlen = sizeof(*greh);
 254         int err = -ENOENT;
 255         __be16 type;
 256
 257         type = greh->protocol;
 258         if (greh->flags & GRE_KEY)
 259                 grehlen += GRE_HEADER_SECTION;
 260
 261         if (greh->flags & GRE_CSUM)
 262                 grehlen += GRE_HEADER_SECTION;
 263
 264         rcu_read_lock();
 265         ptype = gro_find_complete_by_type(type);
 266         if (ptype != NULL)
 267                 err = ptype->callbacks.gro_complete(skb, nhoff + grehlen);
 268
 269         rcu_read_unlock();
 270         return err;
 271 }
 272
 273 static const struct net_offload gre_offload = {
 274         .callbacks = {
 275                 .gso_send_check = gre_gso_send_check,
 276                 .gso_segment = gre_gso_segment,
 277                 .gro_receive = gre_gro_receive,
 278                 .gro_complete = gre_gro_complete,
 279         },
 280 };
 281
 282 static int __init gre_offload_init(void)
 283 {
 284         return inet_add_offload(&gre_offload, IPPROTO_GRE);
 285 }
 286
 287 static void __exit gre_offload_exit(void)
 288 {
 289         inet_del_offload(&gre_offload, IPPROTO_GRE);
 290 }
 291
 292 module_init(gre_offload_init);
 293 module_exit(gre_offload_exit);