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

   1 /*
   2  *      GRE over IPv4 demultiplexer driver
   3  *
   4  *      Authors: Dmitry Kozlov (xeb@mail.ru)
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  *
  11  */
  12
  13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  14
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #include <linux/kmod.h>
  18 #include <linux/skbuff.h>
  19 #include <linux/in.h>
  20 #include <linux/ip.h>
  21 #include <linux/netdevice.h>
  22 #include <linux/if_tunnel.h>
  23 #include <linux/spinlock.h>
  24 #include <net/protocol.h>
  25 #include <net/gre.h>
  26
  27
  28 static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
  29 static DEFINE_SPINLOCK(gre_proto_lock);
  30
  31 int gre_add_protocol(const struct gre_protocol *proto, u8 version)
  32 {
  33         if (version >= GREPROTO_MAX)
  34                 goto err_out;
  35
  36         spin_lock(&gre_proto_lock);
  37         if (gre_proto[version])
  38                 goto err_out_unlock;
  39
  40         RCU_INIT_POINTER(gre_proto[version], proto);
  41         spin_unlock(&gre_proto_lock);
  42         return 0;
  43
  44 err_out_unlock:
  45         spin_unlock(&gre_proto_lock);
  46 err_out:
  47         return -1;
  48 }
  49 EXPORT_SYMBOL_GPL(gre_add_protocol);
  50
  51 int gre_del_protocol(const struct gre_protocol *proto, u8 version)
  52 {
  53         if (version >= GREPROTO_MAX)
  54                 goto err_out;
  55
  56         spin_lock(&gre_proto_lock);
  57         if (rcu_dereference_protected(gre_proto[version],
  58                         lockdep_is_held(&gre_proto_lock)) != proto)
  59                 goto err_out_unlock;
  60         RCU_INIT_POINTER(gre_proto[version], NULL);
  61         spin_unlock(&gre_proto_lock);
  62         synchronize_rcu();
  63         return 0;
  64
  65 err_out_unlock:
  66         spin_unlock(&gre_proto_lock);
  67 err_out:
  68         return -1;
  69 }
  70 EXPORT_SYMBOL_GPL(gre_del_protocol);
  71
  72 static int gre_rcv(struct sk_buff *skb)
  73 {
  74         const struct gre_protocol *proto;
  75         u8 ver;
  76         int ret;
  77
  78         if (!pskb_may_pull(skb, 12))
  79                 goto drop;
  80
  81         ver = skb->data[1]&0x7f;
  82         if (ver >= GREPROTO_MAX)
  83                 goto drop;
  84
  85         rcu_read_lock();
  86         proto = rcu_dereference(gre_proto[ver]);
  87         if (!proto || !proto->handler)
  88                 goto drop_unlock;
  89         ret = proto->handler(skb);
  90         rcu_read_unlock();
  91         return ret;
  92
  93 drop_unlock:
  94         rcu_read_unlock();
  95 drop:
  96         kfree_skb(skb);
  97         return NET_RX_DROP;
  98 }
  99
 100 static void gre_err(struct sk_buff *skb, u32 info)
 101 {
 102         const struct gre_protocol *proto;
 103         const struct iphdr *iph = (const struct iphdr *)skb->data;
 104         u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
 105
 106         if (ver >= GREPROTO_MAX)
 107                 return;
 108
 109         rcu_read_lock();
 110         proto = rcu_dereference(gre_proto[ver]);
 111         if (proto && proto->err_handler)
 112                 proto->err_handler(skb, info);
 113         rcu_read_unlock();
 114 }
 115
 116 static struct sk_buff *gre_gso_segment(struct sk_buff *skb,
 117                                        netdev_features_t features)
 118 {
 119         struct sk_buff *segs = ERR_PTR(-EINVAL);
 120         netdev_features_t enc_features;
 121         int ghl = GRE_HEADER_SECTION;
 122         struct gre_base_hdr *greh;
 123         int mac_len = skb->mac_len;
 124         int tnl_hlen;
 125         bool csum;
 126
 127         if (unlikely(skb_shinfo(skb)->gso_type &
 128                                 ~(SKB_GSO_TCPV4 |
 129                                   SKB_GSO_TCPV6 |
 130                                   SKB_GSO_UDP |
 131                                   SKB_GSO_DODGY |
 132                                   SKB_GSO_TCP_ECN |
 133                                   SKB_GSO_GRE)))
 134                 goto out;
 135
 136         if (unlikely(!pskb_may_pull(skb, sizeof(*greh))))
 137                 goto out;
 138
 139         greh = (struct gre_base_hdr *)skb_transport_header(skb);
 140
 141         if (greh->flags & GRE_KEY)
 142                 ghl += GRE_HEADER_SECTION;
 143         if (greh->flags & GRE_SEQ)
 144                 ghl += GRE_HEADER_SECTION;
 145         if (greh->flags & GRE_CSUM) {
 146                 ghl += GRE_HEADER_SECTION;
 147                 csum = true;
 148         } else
 149                 csum = false;
 150
 151         /* setup inner skb. */
 152         if (greh->protocol == htons(ETH_P_TEB)) {
 153                 struct ethhdr *eth = eth_hdr(skb);
 154                 skb->protocol = eth->h_proto;
 155         } else {
 156                 skb->protocol = greh->protocol;
 157         }
 158
 159         skb->encapsulation = 0;
 160
 161         if (unlikely(!pskb_may_pull(skb, ghl)))
 162                 goto out;
 163         __skb_pull(skb, ghl);
 164         skb_reset_mac_header(skb);
 165         skb_set_network_header(skb, skb_inner_network_offset(skb));
 166         skb->mac_len = skb_inner_network_offset(skb);
 167
 168         /* segment inner packet. */
 169         enc_features = skb->dev->hw_enc_features & netif_skb_features(skb);
 170         segs = skb_mac_gso_segment(skb, enc_features);
 171         if (!segs || IS_ERR(segs))
 172                 goto out;
 173
 174         skb = segs;
 175         tnl_hlen = skb_tnl_header_len(skb);
 176         do {
 177                 __skb_push(skb, ghl);
 178                 if (csum) {
 179                         __be32 *pcsum;
 180
 181                         if (skb_has_shared_frag(skb)) {
 182                                 int err;
 183
 184                                 err = __skb_linearize(skb);
 185                                 if (err) {
 186                                         kfree_skb(segs);
 187                                         segs = ERR_PTR(err);
 188                                         goto out;
 189                                 }
 190                         }
 191
 192                         greh = (struct gre_base_hdr *)(skb->data);
 193                         pcsum = (__be32 *)(greh + 1);
 194                         *pcsum = 0;
 195                         *(__sum16 *)pcsum = csum_fold(skb_checksum(skb, 0, skb->len, 0));
 196                 }
 197                 __skb_push(skb, tnl_hlen - ghl);
 198
 199                 skb_reset_mac_header(skb);
 200                 skb_set_network_header(skb, mac_len);
 201                 skb->mac_len = mac_len;
 202         } while ((skb = skb->next));
 203 out:
 204         return segs;
 205 }
 206
 207 static int gre_gso_send_check(struct sk_buff *skb)
 208 {
 209         if (!skb->encapsulation)
 210                 return -EINVAL;
 211         return 0;
 212 }
 213
 214 static const struct net_protocol net_gre_protocol = {
 215         .handler     = gre_rcv,
 216         .err_handler = gre_err,
 217         .netns_ok    = 1,
 218 };
 219
 220 static const struct net_offload gre_offload = {
 221         .callbacks = {
 222                 .gso_send_check =       gre_gso_send_check,
 223                 .gso_segment    =       gre_gso_segment,
 224         },
 225 };
 226
 227 static int __init gre_init(void)
 228 {
 229         pr_info("GRE over IPv4 demultiplexor driver\n");
 230
 231         if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
 232                 pr_err("can't add protocol\n");
 233                 return -EAGAIN;
 234         }
 235
 236         if (inet_add_offload(&gre_offload, IPPROTO_GRE)) {
 237                 pr_err("can't add protocol offload\n");
 238                 inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
 239                 return -EAGAIN;
 240         }
 241
 242         return 0;
 243 }
 244
 245 static void __exit gre_exit(void)
 246 {
 247         inet_del_offload(&gre_offload, IPPROTO_GRE);
 248         inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
 249 }
 250
 251 module_init(gre_init);
 252 module_exit(gre_exit);
 253
 254 MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
 255 MODULE_AUTHOR("D. Kozlov (xeb@mail.ru)");
 256 MODULE_LICENSE("GPL");
 257