net/openvswitch/vport-gre.c

   1 /*
   2  * Copyright (c) 2007-2014 Nicira, Inc.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of version 2 of the GNU General Public
   6  * License as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but
   9  * WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public License
  14  * along with this program; if not, write to the Free Software
  15  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  16  * 02110-1301, USA
  17  */
  18
  19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  20
  21 #include <linux/if.h>
  22 #include <linux/skbuff.h>
  23 #include <linux/ip.h>
  24 #include <linux/if_tunnel.h>
  25 #include <linux/if_vlan.h>
  26 #include <linux/in.h>
  27 #include <linux/in_route.h>
  28 #include <linux/inetdevice.h>
  29 #include <linux/jhash.h>
  30 #include <linux/list.h>
  31 #include <linux/kernel.h>
  32 #include <linux/module.h>
  33 #include <linux/workqueue.h>
  34 #include <linux/rculist.h>
  35 #include <net/route.h>
  36 #include <net/xfrm.h>
  37
  38 #include <net/icmp.h>
  39 #include <net/ip.h>
  40 #include <net/ip_tunnels.h>
  41 #include <net/gre.h>
  42 #include <net/net_namespace.h>
  43 #include <net/netns/generic.h>
  44 #include <net/protocol.h>
  45
  46 #include "datapath.h"
  47 #include "vport.h"
  48
  49 static struct vport_ops ovs_gre_vport_ops;
  50
  51 /* Returns the least-significant 32 bits of a __be64. */
  52 static __be32 be64_get_low32(__be64 x)
  53 {
  54 #ifdef __BIG_ENDIAN
  55         return (__force __be32)x;
  56 #else
  57         return (__force __be32)((__force u64)x >> 32);
  58 #endif
  59 }
  60
  61 static __be16 filter_tnl_flags(__be16 flags)
  62 {
  63         return flags & (TUNNEL_CSUM | TUNNEL_KEY);
  64 }
  65
  66 static struct sk_buff *__build_header(struct sk_buff *skb,
  67                                       int tunnel_hlen)
  68 {
  69         struct tnl_ptk_info tpi;
  70         const struct ovs_key_ipv4_tunnel *tun_key;
  71
  72         tun_key = &OVS_CB(skb)->egress_tun_info->tunnel;
  73
  74         skb = gre_handle_offloads(skb, !!(tun_key->tun_flags & TUNNEL_CSUM));
  75         if (IS_ERR(skb))
  76                 return skb;
  77
  78         tpi.flags = filter_tnl_flags(tun_key->tun_flags);
  79         tpi.proto = htons(ETH_P_TEB);
  80         tpi.key = be64_get_low32(tun_key->tun_id);
  81         tpi.seq = 0;
  82         gre_build_header(skb, &tpi, tunnel_hlen);
  83
  84         return skb;
  85 }
  86
  87 static __be64 key_to_tunnel_id(__be32 key, __be32 seq)
  88 {
  89 #ifdef __BIG_ENDIAN
  90         return (__force __be64)((__force u64)seq << 32 | (__force u32)key);
  91 #else
  92         return (__force __be64)((__force u64)key << 32 | (__force u32)seq);
  93 #endif
  94 }
  95
  96 /* Called with rcu_read_lock and BH disabled. */
  97 static int gre_rcv(struct sk_buff *skb,
  98                    const struct tnl_ptk_info *tpi)
  99 {
 100         struct ovs_tunnel_info tun_info;
 101         struct ovs_net *ovs_net;
 102         struct vport *vport;
 103         __be64 key;
 104
 105         ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
 106         vport = rcu_dereference(ovs_net->vport_net.gre_vport);
 107         if (unlikely(!vport))
 108                 return PACKET_REJECT;
 109
 110         key = key_to_tunnel_id(tpi->key, tpi->seq);
 111         ovs_flow_tun_info_init(&tun_info, ip_hdr(skb), 0, 0, key,
 112                                filter_tnl_flags(tpi->flags), NULL, 0);
 113
 114         ovs_vport_receive(vport, skb, &tun_info);
 115         return PACKET_RCVD;
 116 }
 117
 118 /* Called with rcu_read_lock and BH disabled. */
 119 static int gre_err(struct sk_buff *skb, u32 info,
 120                    const struct tnl_ptk_info *tpi)
 121 {
 122         struct ovs_net *ovs_net;
 123         struct vport *vport;
 124
 125         ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
 126         vport = rcu_dereference(ovs_net->vport_net.gre_vport);
 127
 128         if (unlikely(!vport))
 129                 return PACKET_REJECT;
 130         else
 131                 return PACKET_RCVD;
 132 }
 133
 134 static int gre_tnl_send(struct vport *vport, struct sk_buff *skb)
 135 {
 136         struct net *net = ovs_dp_get_net(vport->dp);
 137         const struct ovs_key_ipv4_tunnel *tun_key;
 138         struct flowi4 fl;
 139         struct rtable *rt;
 140         int min_headroom;
 141         int tunnel_hlen;
 142         __be16 df;
 143         int err;
 144
 145         if (unlikely(!OVS_CB(skb)->egress_tun_info)) {
 146                 err = -EINVAL;
 147                 goto err_free_skb;
 148         }
 149
 150         tun_key = &OVS_CB(skb)->egress_tun_info->tunnel;
 151         rt = ovs_tunnel_route_lookup(net, tun_key, skb->mark, &fl, IPPROTO_GRE);
 152         if (IS_ERR(rt)) {
 153                 err = PTR_ERR(rt);
 154                 goto err_free_skb;
 155         }
 156
 157         tunnel_hlen = ip_gre_calc_hlen(tun_key->tun_flags);
 158
 159         min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
 160                         + tunnel_hlen + sizeof(struct iphdr)
 161                         + (skb_vlan_tag_present(skb) ? VLAN_HLEN : 0);
 162         if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
 163                 int head_delta = SKB_DATA_ALIGN(min_headroom -
 164                                                 skb_headroom(skb) +
 165                                                 16);
 166                 err = pskb_expand_head(skb, max_t(int, head_delta, 0),
 167                                         0, GFP_ATOMIC);
 168                 if (unlikely(err))
 169                         goto err_free_rt;
 170         }
 171
 172         skb = vlan_hwaccel_push_inside(skb);
 173         if (unlikely(!skb)) {
 174                 err = -ENOMEM;
 175                 goto err_free_rt;
 176         }
 177
 178         /* Push Tunnel header. */
 179         skb = __build_header(skb, tunnel_hlen);
 180         if (IS_ERR(skb)) {
 181                 err = PTR_ERR(skb);
 182                 skb = NULL;
 183                 goto err_free_rt;
 184         }
 185
 186         df = tun_key->tun_flags & TUNNEL_DONT_FRAGMENT ?
 187                 htons(IP_DF) : 0;
 188
 189         skb->ignore_df = 1;
 190
 191         return iptunnel_xmit(skb->sk, rt, skb, fl.saddr,
 192                              tun_key->ipv4_dst, IPPROTO_GRE,
 193                              tun_key->ipv4_tos, tun_key->ipv4_ttl, df, false);
 194 err_free_rt:
 195         ip_rt_put(rt);
 196 err_free_skb:
 197         kfree_skb(skb);
 198         return err;
 199 }
 200
 201 static struct gre_cisco_protocol gre_protocol = {
 202         .handler        = gre_rcv,
 203         .err_handler    = gre_err,
 204         .priority       = 1,
 205 };
 206
 207 static int gre_ports;
 208 static int gre_init(void)
 209 {
 210         int err;
 211
 212         gre_ports++;
 213         if (gre_ports > 1)
 214                 return 0;
 215
 216         err = gre_cisco_register(&gre_protocol);
 217         if (err)
 218                 pr_warn("cannot register gre protocol handler\n");
 219
 220         return err;
 221 }
 222
 223 static void gre_exit(void)
 224 {
 225         gre_ports--;
 226         if (gre_ports > 0)
 227                 return;
 228
 229         gre_cisco_unregister(&gre_protocol);
 230 }
 231
 232 static const char *gre_get_name(const struct vport *vport)
 233 {
 234         return vport_priv(vport);
 235 }
 236
 237 static struct vport *gre_create(const struct vport_parms *parms)
 238 {
 239         struct net *net = ovs_dp_get_net(parms->dp);
 240         struct ovs_net *ovs_net;
 241         struct vport *vport;
 242         int err;
 243
 244         err = gre_init();
 245         if (err)
 246                 return ERR_PTR(err);
 247
 248         ovs_net = net_generic(net, ovs_net_id);
 249         if (ovsl_dereference(ovs_net->vport_net.gre_vport)) {
 250                 vport = ERR_PTR(-EEXIST);
 251                 goto error;
 252         }
 253
 254         vport = ovs_vport_alloc(IFNAMSIZ, &ovs_gre_vport_ops, parms);
 255         if (IS_ERR(vport))
 256                 goto error;
 257
 258         strncpy(vport_priv(vport), parms->name, IFNAMSIZ);
 259         rcu_assign_pointer(ovs_net->vport_net.gre_vport, vport);
 260         return vport;
 261
 262 error:
 263         gre_exit();
 264         return vport;
 265 }
 266
 267 static void gre_tnl_destroy(struct vport *vport)
 268 {
 269         struct net *net = ovs_dp_get_net(vport->dp);
 270         struct ovs_net *ovs_net;
 271
 272         ovs_net = net_generic(net, ovs_net_id);
 273
 274         RCU_INIT_POINTER(ovs_net->vport_net.gre_vport, NULL);
 275         ovs_vport_deferred_free(vport);
 276         gre_exit();
 277 }
 278
 279 static int gre_get_egress_tun_info(struct vport *vport, struct sk_buff *skb,
 280                                    struct ovs_tunnel_info *egress_tun_info)
 281 {
 282         return ovs_tunnel_get_egress_info(egress_tun_info,
 283                                           ovs_dp_get_net(vport->dp),
 284                                           OVS_CB(skb)->egress_tun_info,
 285                                           IPPROTO_GRE, skb->mark, 0, 0);
 286 }
 287
 288 static struct vport_ops ovs_gre_vport_ops = {
 289         .type           = OVS_VPORT_TYPE_GRE,
 290         .create         = gre_create,
 291         .destroy        = gre_tnl_destroy,
 292         .get_name       = gre_get_name,
 293         .send           = gre_tnl_send,
 294         .get_egress_tun_info    = gre_get_egress_tun_info,
 295         .owner          = THIS_MODULE,
 296 };
 297
 298 static int __init ovs_gre_tnl_init(void)
 299 {
 300         return ovs_vport_ops_register(&ovs_gre_vport_ops);
 301 }
 302
 303 static void __exit ovs_gre_tnl_exit(void)
 304 {
 305         ovs_vport_ops_unregister(&ovs_gre_vport_ops);
 306 }
 307
 308 module_init(ovs_gre_tnl_init);
 309 module_exit(ovs_gre_tnl_exit);
 310
 311 MODULE_DESCRIPTION("OVS: GRE switching port");
 312 MODULE_LICENSE("GPL");
 313 MODULE_ALIAS("vport-type-3");