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/if_vlan.h>
  28 #include <linux/in.h>
  29 #include <linux/in_route.h>
  30 #include <linux/inetdevice.h>
  31 #include <linux/jhash.h>
  32 #include <linux/list.h>
  33 #include <linux/kernel.h>
  34 #include <linux/workqueue.h>
  35 #include <linux/rculist.h>
  36 #include <net/route.h>
  37 #include <net/xfrm.h>
  38
  39 #include <net/icmp.h>
  40 #include <net/ip.h>
  41 #include <net/ip_tunnels.h>
  42 #include <net/gre.h>
  43 #include <net/net_namespace.h>
  44 #include <net/netns/generic.h>
  45 #include <net/protocol.h>
  46
  47 #include "datapath.h"
  48 #include "vport.h"
  49
  50 /* Returns the least-significant 32 bits of a __be64. */
  51 static __be32 be64_get_low32(__be64 x)
  52 {
  53 #ifdef __BIG_ENDIAN
  54         return (__force __be32)x;
  55 #else
  56         return (__force __be32)((__force u64)x >> 32);
  57 #endif
  58 }
  59
  60 static __be16 filter_tnl_flags(__be16 flags)
  61 {
  62         return flags & (TUNNEL_CSUM | TUNNEL_KEY);
  63 }
  64
  65 static struct sk_buff *__build_header(struct sk_buff *skb,
  66                                       int tunnel_hlen)
  67 {
  68         const struct ovs_key_ipv4_tunnel *tun_key = OVS_CB(skb)->tun_key;
  69         struct tnl_ptk_info tpi;
  70
  71         skb = gre_handle_offloads(skb, !!(tun_key->tun_flags & TUNNEL_CSUM));
  72         if (IS_ERR(skb))
  73                 return NULL;
  74
  75         tpi.flags = filter_tnl_flags(tun_key->tun_flags);
  76         tpi.proto = htons(ETH_P_TEB);
  77         tpi.key = be64_get_low32(tun_key->tun_id);
  78         tpi.seq = 0;
  79         gre_build_header(skb, &tpi, tunnel_hlen);
  80
  81         return skb;
  82 }
  83
  84 static __be64 key_to_tunnel_id(__be32 key, __be32 seq)
  85 {
  86 #ifdef __BIG_ENDIAN
  87         return (__force __be64)((__force u64)seq << 32 | (__force u32)key);
  88 #else
  89         return (__force __be64)((__force u64)key << 32 | (__force u32)seq);
  90 #endif
  91 }
  92
  93 /* Called with rcu_read_lock and BH disabled. */
  94 static int gre_rcv(struct sk_buff *skb,
  95                    const struct tnl_ptk_info *tpi)
  96 {
  97         struct ovs_key_ipv4_tunnel tun_key;
  98         struct ovs_net *ovs_net;
  99         struct vport *vport;
 100         __be64 key;
 101
 102         ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
 103         vport = rcu_dereference(ovs_net->vport_net.gre_vport);
 104         if (unlikely(!vport))
 105                 return PACKET_REJECT;
 106
 107         key = key_to_tunnel_id(tpi->key, tpi->seq);
 108         ovs_flow_tun_key_init(&tun_key, ip_hdr(skb), key,
 109                               filter_tnl_flags(tpi->flags));
 110
 111         ovs_vport_receive(vport, skb, &tun_key);
 112         return PACKET_RCVD;
 113 }
 114
 115 static int gre_tnl_send(struct vport *vport, struct sk_buff *skb)
 116 {
 117         struct net *net = ovs_dp_get_net(vport->dp);
 118         struct flowi4 fl;
 119         struct rtable *rt;
 120         int min_headroom;
 121         int tunnel_hlen;
 122         __be16 df;
 123         int err;
 124
 125         if (unlikely(!OVS_CB(skb)->tun_key)) {
 126                 err = -EINVAL;
 127                 goto error;
 128         }
 129
 130         /* Route lookup */
 131         memset(&fl, 0, sizeof(fl));
 132         fl.daddr = OVS_CB(skb)->tun_key->ipv4_dst;
 133         fl.saddr = OVS_CB(skb)->tun_key->ipv4_src;
 134         fl.flowi4_tos = RT_TOS(OVS_CB(skb)->tun_key->ipv4_tos);
 135         fl.flowi4_mark = skb->mark;
 136         fl.flowi4_proto = IPPROTO_GRE;
 137
 138         rt = ip_route_output_key(net, &fl);
 139         if (IS_ERR(rt))
 140                 return PTR_ERR(rt);
 141
 142         tunnel_hlen = ip_gre_calc_hlen(OVS_CB(skb)->tun_key->tun_flags);
 143
 144         min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
 145                         + tunnel_hlen + sizeof(struct iphdr)
 146                         + (vlan_tx_tag_present(skb) ? VLAN_HLEN : 0);
 147         if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
 148                 int head_delta = SKB_DATA_ALIGN(min_headroom -
 149                                                 skb_headroom(skb) +
 150                                                 16);
 151                 err = pskb_expand_head(skb, max_t(int, head_delta, 0),
 152                                         0, GFP_ATOMIC);
 153                 if (unlikely(err))
 154                         goto err_free_rt;
 155         }
 156
 157         if (vlan_tx_tag_present(skb)) {
 158                 if (unlikely(!__vlan_put_tag(skb,
 159                                              skb->vlan_proto,
 160                                              vlan_tx_tag_get(skb)))) {
 161                         err = -ENOMEM;
 162                         goto err_free_rt;
 163                 }
 164                 skb->vlan_tci = 0;
 165         }
 166
 167         /* Push Tunnel header. */
 168         skb = __build_header(skb, tunnel_hlen);
 169         if (unlikely(!skb)) {
 170                 err = 0;
 171                 goto err_free_rt;
 172         }
 173
 174         df = OVS_CB(skb)->tun_key->tun_flags & TUNNEL_DONT_FRAGMENT ?
 175                 htons(IP_DF) : 0;
 176
 177         skb->local_df = 1;
 178
 179         return iptunnel_xmit(rt, skb, fl.saddr,
 180                              OVS_CB(skb)->tun_key->ipv4_dst, IPPROTO_GRE,
 181                              OVS_CB(skb)->tun_key->ipv4_tos,
 182                              OVS_CB(skb)->tun_key->ipv4_ttl, df, false);
 183 err_free_rt:
 184         ip_rt_put(rt);
 185 error:
 186         return err;
 187 }
 188
 189 static struct gre_cisco_protocol gre_protocol = {
 190         .handler        = gre_rcv,
 191         .priority       = 1,
 192 };
 193
 194 static int gre_ports;
 195 static int gre_init(void)
 196 {
 197         int err;
 198
 199         gre_ports++;
 200         if (gre_ports > 1)
 201                 return 0;
 202
 203         err = gre_cisco_register(&gre_protocol);
 204         if (err)
 205                 pr_warn("cannot register gre protocol handler\n");
 206
 207         return err;
 208 }
 209
 210 static void gre_exit(void)
 211 {
 212         gre_ports--;
 213         if (gre_ports > 0)
 214                 return;
 215
 216         gre_cisco_unregister(&gre_protocol);
 217 }
 218
 219 static const char *gre_get_name(const struct vport *vport)
 220 {
 221         return vport_priv(vport);
 222 }
 223
 224 static struct vport *gre_create(const struct vport_parms *parms)
 225 {
 226         struct net *net = ovs_dp_get_net(parms->dp);
 227         struct ovs_net *ovs_net;
 228         struct vport *vport;
 229         int err;
 230
 231         err = gre_init();
 232         if (err)
 233                 return ERR_PTR(err);
 234
 235         ovs_net = net_generic(net, ovs_net_id);
 236         if (ovsl_dereference(ovs_net->vport_net.gre_vport)) {
 237                 vport = ERR_PTR(-EEXIST);
 238                 goto error;
 239         }
 240
 241         vport = ovs_vport_alloc(IFNAMSIZ, &ovs_gre_vport_ops, parms);
 242         if (IS_ERR(vport))
 243                 goto error;
 244
 245         strncpy(vport_priv(vport), parms->name, IFNAMSIZ);
 246         rcu_assign_pointer(ovs_net->vport_net.gre_vport, vport);
 247         return vport;
 248
 249 error:
 250         gre_exit();
 251         return vport;
 252 }
 253
 254 static void gre_tnl_destroy(struct vport *vport)
 255 {
 256         struct net *net = ovs_dp_get_net(vport->dp);
 257         struct ovs_net *ovs_net;
 258
 259         ovs_net = net_generic(net, ovs_net_id);
 260
 261         rcu_assign_pointer(ovs_net->vport_net.gre_vport, NULL);
 262         ovs_vport_deferred_free(vport);
 263         gre_exit();
 264 }
 265
 266 const struct vport_ops ovs_gre_vport_ops = {
 267         .type           = OVS_VPORT_TYPE_GRE,
 268         .create         = gre_create,
 269         .destroy        = gre_tnl_destroy,
 270         .get_name       = gre_get_name,
 271         .send           = gre_tnl_send,
 272 };