net/openvswitch/vport-gre.c

   1 /*
   2  * Copyright (c) 2007-2013 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 #ifdef CONFIG_OPENVSWITCH_GRE
  20 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  21
  22 #include <linux/if.h>
  23 #include <linux/skbuff.h>
  24 #include <linux/ip.h>
  25 #include <linux/if_tunnel.h>
  26 #include <linux/if_vlan.h>
  27 #include <linux/in.h>
  28 #include <linux/if_vlan.h>
  29 #include <linux/in.h>
  30 #include <linux/in_route.h>
  31 #include <linux/inetdevice.h>
  32 #include <linux/jhash.h>
  33 #include <linux/list.h>
  34 #include <linux/kernel.h>
  35 #include <linux/workqueue.h>
  36 #include <linux/rculist.h>
  37 #include <net/route.h>
  38 #include <net/xfrm.h>
  39
  40 #include <net/icmp.h>
  41 #include <net/ip.h>
  42 #include <net/ip_tunnels.h>
  43 #include <net/gre.h>
  44 #include <net/net_namespace.h>
  45 #include <net/netns/generic.h>
  46 #include <net/protocol.h>
  47
  48 #include "datapath.h"
  49 #include "vport.h"
  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         const struct ovs_key_ipv4_tunnel *tun_key = OVS_CB(skb)->tun_key;
  70         struct tnl_ptk_info tpi;
  71
  72         skb = gre_handle_offloads(skb, !!(tun_key->tun_flags & TUNNEL_CSUM));
  73         if (IS_ERR(skb))
  74                 return NULL;
  75
  76         tpi.flags = filter_tnl_flags(tun_key->tun_flags);
  77         tpi.proto = htons(ETH_P_TEB);
  78         tpi.key = be64_get_low32(tun_key->tun_id);
  79         tpi.seq = 0;
  80         gre_build_header(skb, &tpi, tunnel_hlen);
  81
  82         return skb;
  83 }
  84
  85 static __be64 key_to_tunnel_id(__be32 key, __be32 seq)
  86 {
  87 #ifdef __BIG_ENDIAN
  88         return (__force __be64)((__force u64)seq << 32 | (__force u32)key);
  89 #else
  90         return (__force __be64)((__force u64)key << 32 | (__force u32)seq);
  91 #endif
  92 }
  93
  94 /* Called with rcu_read_lock and BH disabled. */
  95 static int gre_rcv(struct sk_buff *skb,
  96                    const struct tnl_ptk_info *tpi)
  97 {
  98         struct ovs_key_ipv4_tunnel tun_key;
  99         struct ovs_net *ovs_net;
 100         struct vport *vport;
 101         __be64 key;
 102
 103         ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
 104         vport = rcu_dereference(ovs_net->vport_net.gre_vport);
 105         if (unlikely(!vport))
 106                 return PACKET_REJECT;
 107
 108         key = key_to_tunnel_id(tpi->key, tpi->seq);
 109         ovs_flow_tun_key_init(&tun_key, ip_hdr(skb), key,
 110                               filter_tnl_flags(tpi->flags));
 111
 112         ovs_vport_receive(vport, skb, &tun_key);
 113         return PACKET_RCVD;
 114 }
 115
 116 static int gre_tnl_send(struct vport *vport, struct sk_buff *skb)
 117 {
 118         struct net *net = ovs_dp_get_net(vport->dp);
 119         struct flowi4 fl;
 120         struct rtable *rt;
 121         int min_headroom;
 122         int tunnel_hlen;
 123         __be16 df;
 124         int err;
 125
 126         if (unlikely(!OVS_CB(skb)->tun_key)) {
 127                 err = -EINVAL;
 128                 goto error;
 129         }
 130
 131         /* Route lookup */
 132         memset(&fl, 0, sizeof(fl));
 133         fl.daddr = OVS_CB(skb)->tun_key->ipv4_dst;
 134         fl.saddr = OVS_CB(skb)->tun_key->ipv4_src;
 135         fl.flowi4_tos = RT_TOS(OVS_CB(skb)->tun_key->ipv4_tos);
 136         fl.flowi4_mark = skb->mark;
 137         fl.flowi4_proto = IPPROTO_GRE;
 138
 139         rt = ip_route_output_key(net, &fl);
 140         if (IS_ERR(rt))
 141                 return PTR_ERR(rt);
 142
 143         tunnel_hlen = ip_gre_calc_hlen(OVS_CB(skb)->tun_key->tun_flags);
 144
 145         min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
 146                         + tunnel_hlen + sizeof(struct iphdr)
 147                         + (vlan_tx_tag_present(skb) ? VLAN_HLEN : 0);
 148         if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
 149                 int head_delta = SKB_DATA_ALIGN(min_headroom -
 150                                                 skb_headroom(skb) +
 151                                                 16);
 152                 err = pskb_expand_head(skb, max_t(int, head_delta, 0),
 153                                         0, GFP_ATOMIC);
 154                 if (unlikely(err))
 155                         goto err_free_rt;
 156         }
 157
 158         if (vlan_tx_tag_present(skb)) {
 159                 if (unlikely(!__vlan_put_tag(skb,
 160                                              skb->vlan_proto,
 161                                              vlan_tx_tag_get(skb)))) {
 162                         err = -ENOMEM;
 163                         goto err_free_rt;
 164                 }
 165                 skb->vlan_tci = 0;
 166         }
 167
 168         /* Push Tunnel header. */
 169         skb = __build_header(skb, tunnel_hlen);
 170         if (unlikely(!skb)) {
 171                 err = 0;
 172                 goto err_free_rt;
 173         }
 174
 175         df = OVS_CB(skb)->tun_key->tun_flags & TUNNEL_DONT_FRAGMENT ?
 176                 htons(IP_DF) : 0;
 177
 178         skb->local_df = 1;
 179
 180         return iptunnel_xmit(net, rt, skb, fl.saddr,
 181                              OVS_CB(skb)->tun_key->ipv4_dst, IPPROTO_GRE,
 182                              OVS_CB(skb)->tun_key->ipv4_tos,
 183                              OVS_CB(skb)->tun_key->ipv4_ttl, df);
 184 err_free_rt:
 185         ip_rt_put(rt);
 186 error:
 187         return err;
 188 }
 189
 190 static struct gre_cisco_protocol gre_protocol = {
 191         .handler        = gre_rcv,
 192         .priority       = 1,
 193 };
 194
 195 static int gre_ports;
 196 static int gre_init(void)
 197 {
 198         int err;
 199
 200         gre_ports++;
 201         if (gre_ports > 1)
 202                 return 0;
 203
 204         err = gre_cisco_register(&gre_protocol);
 205         if (err)
 206                 pr_warn("cannot register gre protocol handler\n");
 207
 208         return err;
 209 }
 210
 211 static void gre_exit(void)
 212 {
 213         gre_ports--;
 214         if (gre_ports > 0)
 215                 return;
 216
 217         gre_cisco_unregister(&gre_protocol);
 218 }
 219
 220 static const char *gre_get_name(const struct vport *vport)
 221 {
 222         return vport_priv(vport);
 223 }
 224
 225 static struct vport *gre_create(const struct vport_parms *parms)
 226 {
 227         struct net *net = ovs_dp_get_net(parms->dp);
 228         struct ovs_net *ovs_net;
 229         struct vport *vport;
 230         int err;
 231
 232         err = gre_init();
 233         if (err)
 234                 return ERR_PTR(err);
 235
 236         ovs_net = net_generic(net, ovs_net_id);
 237         if (ovsl_dereference(ovs_net->vport_net.gre_vport)) {
 238                 vport = ERR_PTR(-EEXIST);
 239                 goto error;
 240         }
 241
 242         vport = ovs_vport_alloc(IFNAMSIZ, &ovs_gre_vport_ops, parms);
 243         if (IS_ERR(vport))
 244                 goto error;
 245
 246         strncpy(vport_priv(vport), parms->name, IFNAMSIZ);
 247         rcu_assign_pointer(ovs_net->vport_net.gre_vport, vport);
 248         return vport;
 249
 250 error:
 251         gre_exit();
 252         return vport;
 253 }
 254
 255 static void gre_tnl_destroy(struct vport *vport)
 256 {
 257         struct net *net = ovs_dp_get_net(vport->dp);
 258         struct ovs_net *ovs_net;
 259
 260         ovs_net = net_generic(net, ovs_net_id);
 261
 262         rcu_assign_pointer(ovs_net->vport_net.gre_vport, NULL);
 263         ovs_vport_deferred_free(vport);
 264         gre_exit();
 265 }
 266
 267 const struct vport_ops ovs_gre_vport_ops = {
 268         .type           = OVS_VPORT_TYPE_GRE,
 269         .create         = gre_create,
 270         .destroy        = gre_tnl_destroy,
 271         .get_name       = gre_get_name,
 272         .send           = gre_tnl_send,
 273 };
 274
 275 #endif /* OPENVSWITCH_GRE */