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 #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/workqueue.h>
  33 #include <linux/rculist.h>
  34 #include <net/route.h>
  35 #include <net/xfrm.h>
  36
  37 #include <net/icmp.h>
  38 #include <net/ip.h>
  39 #include <net/ip_tunnels.h>
  40 #include <net/gre.h>
  41 #include <net/net_namespace.h>
  42 #include <net/netns/generic.h>
  43 #include <net/protocol.h>
  44
  45 #include "datapath.h"
  46 #include "vport.h"
  47
  48 /* Returns the least-significant 32 bits of a __be64. */
  49 static __be32 be64_get_low32(__be64 x)
  50 {
  51 #ifdef __BIG_ENDIAN
  52         return (__force __be32)x;
  53 #else
  54         return (__force __be32)((__force u64)x >> 32);
  55 #endif
  56 }
  57
  58 static __be16 filter_tnl_flags(__be16 flags)
  59 {
  60         return flags & (TUNNEL_CSUM | TUNNEL_KEY);
  61 }
  62
  63 static struct sk_buff *__build_header(struct sk_buff *skb,
  64                                       int tunnel_hlen)
  65 {
  66         const struct ovs_key_ipv4_tunnel *tun_key = OVS_CB(skb)->tun_key;
  67         struct tnl_ptk_info tpi;
  68
  69         skb = gre_handle_offloads(skb, !!(tun_key->tun_flags & TUNNEL_CSUM));
  70         if (IS_ERR(skb))
  71                 return NULL;
  72
  73         tpi.flags = filter_tnl_flags(tun_key->tun_flags);
  74         tpi.proto = htons(ETH_P_TEB);
  75         tpi.key = be64_get_low32(tun_key->tun_id);
  76         tpi.seq = 0;
  77         gre_build_header(skb, &tpi, tunnel_hlen);
  78
  79         return skb;
  80 }
  81
  82 static __be64 key_to_tunnel_id(__be32 key, __be32 seq)
  83 {
  84 #ifdef __BIG_ENDIAN
  85         return (__force __be64)((__force u64)seq << 32 | (__force u32)key);
  86 #else
  87         return (__force __be64)((__force u64)key << 32 | (__force u32)seq);
  88 #endif
  89 }
  90
  91 /* Called with rcu_read_lock and BH disabled. */
  92 static int gre_rcv(struct sk_buff *skb,
  93                    const struct tnl_ptk_info *tpi)
  94 {
  95         struct ovs_key_ipv4_tunnel tun_key;
  96         struct ovs_net *ovs_net;
  97         struct vport *vport;
  98         __be64 key;
  99
 100         ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
 101         vport = rcu_dereference(ovs_net->vport_net.gre_vport);
 102         if (unlikely(!vport))
 103                 return PACKET_REJECT;
 104
 105         key = key_to_tunnel_id(tpi->key, tpi->seq);
 106         ovs_flow_tun_key_init(&tun_key, ip_hdr(skb), key,
 107                               filter_tnl_flags(tpi->flags));
 108
 109         ovs_vport_receive(vport, skb, &tun_key);
 110         return PACKET_RCVD;
 111 }
 112
 113 static int gre_tnl_send(struct vport *vport, struct sk_buff *skb)
 114 {
 115         struct net *net = ovs_dp_get_net(vport->dp);
 116         struct flowi4 fl;
 117         struct rtable *rt;
 118         int min_headroom;
 119         int tunnel_hlen;
 120         __be16 df;
 121         int err;
 122
 123         if (unlikely(!OVS_CB(skb)->tun_key)) {
 124                 err = -EINVAL;
 125                 goto error;
 126         }
 127
 128         /* Route lookup */
 129         memset(&fl, 0, sizeof(fl));
 130         fl.daddr = OVS_CB(skb)->tun_key->ipv4_dst;
 131         fl.saddr = OVS_CB(skb)->tun_key->ipv4_src;
 132         fl.flowi4_tos = RT_TOS(OVS_CB(skb)->tun_key->ipv4_tos);
 133         fl.flowi4_mark = skb->mark;
 134         fl.flowi4_proto = IPPROTO_GRE;
 135
 136         rt = ip_route_output_key(net, &fl);
 137         if (IS_ERR(rt))
 138                 return PTR_ERR(rt);
 139
 140         tunnel_hlen = ip_gre_calc_hlen(OVS_CB(skb)->tun_key->tun_flags);
 141
 142         min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
 143                         + tunnel_hlen + sizeof(struct iphdr)
 144                         + (vlan_tx_tag_present(skb) ? VLAN_HLEN : 0);
 145         if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
 146                 int head_delta = SKB_DATA_ALIGN(min_headroom -
 147                                                 skb_headroom(skb) +
 148                                                 16);
 149                 err = pskb_expand_head(skb, max_t(int, head_delta, 0),
 150                                         0, GFP_ATOMIC);
 151                 if (unlikely(err))
 152                         goto err_free_rt;
 153         }
 154
 155         if (vlan_tx_tag_present(skb)) {
 156                 if (unlikely(!__vlan_put_tag(skb,
 157                                              skb->vlan_proto,
 158                                              vlan_tx_tag_get(skb)))) {
 159                         err = -ENOMEM;
 160                         goto err_free_rt;
 161                 }
 162                 skb->vlan_tci = 0;
 163         }
 164
 165         /* Push Tunnel header. */
 166         skb = __build_header(skb, tunnel_hlen);
 167         if (unlikely(!skb)) {
 168                 err = 0;
 169                 goto err_free_rt;
 170         }
 171
 172         df = OVS_CB(skb)->tun_key->tun_flags & TUNNEL_DONT_FRAGMENT ?
 173                 htons(IP_DF) : 0;
 174
 175         skb->ignore_df = 1;
 176
 177         return iptunnel_xmit(skb->sk, rt, skb, fl.saddr,
 178                              OVS_CB(skb)->tun_key->ipv4_dst, IPPROTO_GRE,
 179                              OVS_CB(skb)->tun_key->ipv4_tos,
 180                              OVS_CB(skb)->tun_key->ipv4_ttl, df, false);
 181 err_free_rt:
 182         ip_rt_put(rt);
 183 error:
 184         return err;
 185 }
 186
 187 static struct gre_cisco_protocol gre_protocol = {
 188         .handler        = gre_rcv,
 189         .priority       = 1,
 190 };
 191
 192 static int gre_ports;
 193 static int gre_init(void)
 194 {
 195         int err;
 196
 197         gre_ports++;
 198         if (gre_ports > 1)
 199                 return 0;
 200
 201         err = gre_cisco_register(&gre_protocol);
 202         if (err)
 203                 pr_warn("cannot register gre protocol handler\n");
 204
 205         return err;
 206 }
 207
 208 static void gre_exit(void)
 209 {
 210         gre_ports--;
 211         if (gre_ports > 0)
 212                 return;
 213
 214         gre_cisco_unregister(&gre_protocol);
 215 }
 216
 217 static const char *gre_get_name(const struct vport *vport)
 218 {
 219         return vport_priv(vport);
 220 }
 221
 222 static struct vport *gre_create(const struct vport_parms *parms)
 223 {
 224         struct net *net = ovs_dp_get_net(parms->dp);
 225         struct ovs_net *ovs_net;
 226         struct vport *vport;
 227         int err;
 228
 229         err = gre_init();
 230         if (err)
 231                 return ERR_PTR(err);
 232
 233         ovs_net = net_generic(net, ovs_net_id);
 234         if (ovsl_dereference(ovs_net->vport_net.gre_vport)) {
 235                 vport = ERR_PTR(-EEXIST);
 236                 goto error;
 237         }
 238
 239         vport = ovs_vport_alloc(IFNAMSIZ, &ovs_gre_vport_ops, parms);
 240         if (IS_ERR(vport))
 241                 goto error;
 242
 243         strncpy(vport_priv(vport), parms->name, IFNAMSIZ);
 244         rcu_assign_pointer(ovs_net->vport_net.gre_vport, vport);
 245         return vport;
 246
 247 error:
 248         gre_exit();
 249         return vport;
 250 }
 251
 252 static void gre_tnl_destroy(struct vport *vport)
 253 {
 254         struct net *net = ovs_dp_get_net(vport->dp);
 255         struct ovs_net *ovs_net;
 256
 257         ovs_net = net_generic(net, ovs_net_id);
 258
 259         RCU_INIT_POINTER(ovs_net->vport_net.gre_vport, NULL);
 260         ovs_vport_deferred_free(vport);
 261         gre_exit();
 262 }
 263
 264 const struct vport_ops ovs_gre_vport_ops = {
 265         .type           = OVS_VPORT_TYPE_GRE,
 266         .create         = gre_create,
 267         .destroy        = gre_tnl_destroy,
 268         .get_name       = gre_get_name,
 269         .send           = gre_tnl_send,
 270 };