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/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         struct tnl_ptk_info tpi;
  67         const struct ovs_key_ipv4_tunnel *tun_key;
  68
  69         tun_key = &OVS_CB(skb)->egress_tun_info->tunnel;
  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_tunnel_info tun_info;
  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_info_init(&tun_info, ip_hdr(skb), key,
 109                                filter_tnl_flags(tpi->flags), NULL, 0);
 110
 111         ovs_vport_receive(vport, skb, &tun_info);
 112         return PACKET_RCVD;
 113 }
 114
 115 /* Called with rcu_read_lock and BH disabled. */
 116 static int gre_err(struct sk_buff *skb, u32 info,
 117                    const struct tnl_ptk_info *tpi)
 118 {
 119         struct ovs_net *ovs_net;
 120         struct vport *vport;
 121
 122         ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
 123         vport = rcu_dereference(ovs_net->vport_net.gre_vport);
 124
 125         if (unlikely(!vport))
 126                 return PACKET_REJECT;
 127         else
 128                 return PACKET_RCVD;
 129 }
 130
 131 static int gre_tnl_send(struct vport *vport, struct sk_buff *skb)
 132 {
 133         struct net *net = ovs_dp_get_net(vport->dp);
 134         struct ovs_key_ipv4_tunnel *tun_key;
 135         struct flowi4 fl;
 136         struct rtable *rt;
 137         int min_headroom;
 138         int tunnel_hlen;
 139         __be16 df;
 140         int err;
 141
 142         if (unlikely(!OVS_CB(skb)->egress_tun_info)) {
 143                 err = -EINVAL;
 144                 goto error;
 145         }
 146
 147         tun_key = &OVS_CB(skb)->egress_tun_info->tunnel;
 148         /* Route lookup */
 149         memset(&fl, 0, sizeof(fl));
 150         fl.daddr = tun_key->ipv4_dst;
 151         fl.saddr = tun_key->ipv4_src;
 152         fl.flowi4_tos = RT_TOS(tun_key->ipv4_tos);
 153         fl.flowi4_mark = skb->mark;
 154         fl.flowi4_proto = IPPROTO_GRE;
 155
 156         rt = ip_route_output_key(net, &fl);
 157         if (IS_ERR(rt))
 158                 return PTR_ERR(rt);
 159
 160         tunnel_hlen = ip_gre_calc_hlen(tun_key->tun_flags);
 161
 162         min_headroom = LL_RESERVED_SPACE(rt->dst.dev) + rt->dst.header_len
 163                         + tunnel_hlen + sizeof(struct iphdr)
 164                         + (vlan_tx_tag_present(skb) ? VLAN_HLEN : 0);
 165         if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
 166                 int head_delta = SKB_DATA_ALIGN(min_headroom -
 167                                                 skb_headroom(skb) +
 168                                                 16);
 169                 err = pskb_expand_head(skb, max_t(int, head_delta, 0),
 170                                         0, GFP_ATOMIC);
 171                 if (unlikely(err))
 172                         goto err_free_rt;
 173         }
 174
 175         skb = vlan_hwaccel_push_inside(skb);
 176         if (unlikely(!skb)) {
 177                 err = -ENOMEM;
 178                 goto err_free_rt;
 179         }
 180
 181         /* Push Tunnel header. */
 182         skb = __build_header(skb, tunnel_hlen);
 183         if (unlikely(!skb)) {
 184                 err = 0;
 185                 goto err_free_rt;
 186         }
 187
 188         df = tun_key->tun_flags & TUNNEL_DONT_FRAGMENT ?
 189                 htons(IP_DF) : 0;
 190
 191         skb->ignore_df = 1;
 192
 193         return iptunnel_xmit(skb->sk, rt, skb, fl.saddr,
 194                              tun_key->ipv4_dst, IPPROTO_GRE,
 195                              tun_key->ipv4_tos, tun_key->ipv4_ttl, df, false);
 196 err_free_rt:
 197         ip_rt_put(rt);
 198 error:
 199         return err;
 200 }
 201
 202 static struct gre_cisco_protocol gre_protocol = {
 203         .handler        = gre_rcv,
 204         .err_handler    = gre_err,
 205         .priority       = 1,
 206 };
 207
 208 static int gre_ports;
 209 static int gre_init(void)
 210 {
 211         int err;
 212
 213         gre_ports++;
 214         if (gre_ports > 1)
 215                 return 0;
 216
 217         err = gre_cisco_register(&gre_protocol);
 218         if (err)
 219                 pr_warn("cannot register gre protocol handler\n");
 220
 221         return err;
 222 }
 223
 224 static void gre_exit(void)
 225 {
 226         gre_ports--;
 227         if (gre_ports > 0)
 228                 return;
 229
 230         gre_cisco_unregister(&gre_protocol);
 231 }
 232
 233 static const char *gre_get_name(const struct vport *vport)
 234 {
 235         return vport_priv(vport);
 236 }
 237
 238 static struct vport *gre_create(const struct vport_parms *parms)
 239 {
 240         struct net *net = ovs_dp_get_net(parms->dp);
 241         struct ovs_net *ovs_net;
 242         struct vport *vport;
 243         int err;
 244
 245         err = gre_init();
 246         if (err)
 247                 return ERR_PTR(err);
 248
 249         ovs_net = net_generic(net, ovs_net_id);
 250         if (ovsl_dereference(ovs_net->vport_net.gre_vport)) {
 251                 vport = ERR_PTR(-EEXIST);
 252                 goto error;
 253         }
 254
 255         vport = ovs_vport_alloc(IFNAMSIZ, &ovs_gre_vport_ops, parms);
 256         if (IS_ERR(vport))
 257                 goto error;
 258
 259         strncpy(vport_priv(vport), parms->name, IFNAMSIZ);
 260         rcu_assign_pointer(ovs_net->vport_net.gre_vport, vport);
 261         return vport;
 262
 263 error:
 264         gre_exit();
 265         return vport;
 266 }
 267
 268 static void gre_tnl_destroy(struct vport *vport)
 269 {
 270         struct net *net = ovs_dp_get_net(vport->dp);
 271         struct ovs_net *ovs_net;
 272
 273         ovs_net = net_generic(net, ovs_net_id);
 274
 275         RCU_INIT_POINTER(ovs_net->vport_net.gre_vport, NULL);
 276         ovs_vport_deferred_free(vport);
 277         gre_exit();
 278 }
 279
 280 const struct vport_ops ovs_gre_vport_ops = {
 281         .type           = OVS_VPORT_TYPE_GRE,
 282         .create         = gre_create,
 283         .destroy        = gre_tnl_destroy,
 284         .get_name       = gre_get_name,
 285         .send           = gre_tnl_send,
 286 };