datapath/vport-gre.c

   1 /*
   2  * Copyright (c) 2007-2015 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 #include <linux/kconfig.h>
  20 #if IS_ENABLED(CONFIG_NET_IPGRE_DEMUX)
  21
  22 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  23
  24 #include <linux/if.h>
  25 #include <linux/skbuff.h>
  26 #include <linux/ip.h>
  27 #include <linux/if_tunnel.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/module.h>
  36 #include <linux/workqueue.h>
  37 #include <linux/rculist.h>
  38 #include <net/route.h>
  39 #include <net/xfrm.h>
  40
  41 #include <net/icmp.h>
  42 #include <net/ip.h>
  43 #include <net/ip_tunnels.h>
  44 #include <net/gre.h>
  45 #include <net/net_namespace.h>
  46 #include <net/netns/generic.h>
  47 #include <net/protocol.h>
  48
  49 #include "datapath.h"
  50 #include "vport.h"
  51
  52 static struct vport_ops ovs_gre_vport_ops;
  53
  54 /* Returns the least-significant 32 bits of a __be64. */
  55 static __be32 be64_get_low32(__be64 x)
  56 {
  57 #ifdef __BIG_ENDIAN
  58         return (__force __be32)x;
  59 #else
  60         return (__force __be32)((__force u64)x >> 32);
  61 #endif
  62 }
  63
  64 static __be16 filter_tnl_flags(__be16 flags)
  65 {
  66         return flags & (TUNNEL_CSUM | TUNNEL_KEY);
  67 }
  68
  69 static struct sk_buff *__build_header(struct sk_buff *skb,
  70                                       int tunnel_hlen)
  71 {
  72         struct tnl_ptk_info tpi;
  73         const struct ovs_key_ipv4_tunnel *tun_key;
  74
  75         tun_key = &OVS_CB(skb)->egress_tun_info->tunnel;
  76
  77         skb = gre_handle_offloads(skb, !!(tun_key->tun_flags & TUNNEL_CSUM));
  78         if (IS_ERR(skb))
  79                 return skb;
  80
  81         tpi.flags = filter_tnl_flags(tun_key->tun_flags);
  82         tpi.proto = htons(ETH_P_TEB);
  83         tpi.key = be64_get_low32(tun_key->tun_id);
  84         tpi.seq = 0;
  85         gre_build_header(skb, &tpi, tunnel_hlen);
  86
  87         return skb;
  88 }
  89
  90 static __be64 key_to_tunnel_id(__be32 key, __be32 seq)
  91 {
  92 #ifdef __BIG_ENDIAN
  93         return (__force __be64)((__force u64)seq << 32 | (__force u32)key);
  94 #else
  95         return (__force __be64)((__force u64)key << 32 | (__force u32)seq);
  96 #endif
  97 }
  98
  99 /* Called with rcu_read_lock and BH disabled. */
 100 static int gre_rcv(struct sk_buff *skb,
 101                    const struct tnl_ptk_info *tpi)
 102 {
 103         struct ovs_tunnel_info tun_info;
 104         struct ovs_net *ovs_net;
 105         struct vport *vport;
 106         __be64 key;
 107
 108         ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
 109         vport = rcu_dereference(ovs_net->vport_net.gre_vport);
 110         if (unlikely(!vport))
 111                 return PACKET_REJECT;
 112
 113         key = key_to_tunnel_id(tpi->key, tpi->seq);
 114         ovs_flow_tun_info_init(&tun_info, ip_hdr(skb), 0, 0, key,
 115                                filter_tnl_flags(tpi->flags), NULL, 0);
 116
 117         ovs_vport_receive(vport, skb, &tun_info);
 118         return PACKET_RCVD;
 119 }
 120
 121 /* Called with rcu_read_lock and BH disabled. */
 122 static int gre_err(struct sk_buff *skb, u32 info,
 123                    const struct tnl_ptk_info *tpi)
 124 {
 125         struct ovs_net *ovs_net;
 126         struct vport *vport;
 127
 128         ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
 129         vport = rcu_dereference(ovs_net->vport_net.gre_vport);
 130
 131         if (unlikely(!vport))
 132                 return PACKET_REJECT;
 133         else
 134                 return PACKET_RCVD;
 135 }
 136
 137 static int gre_tnl_send(struct vport *vport, struct sk_buff *skb)
 138 {
 139         const struct ovs_key_ipv4_tunnel *tun_key;
 140         struct rtable *rt;
 141         int min_headroom;
 142         __be16 df;
 143         int tunnel_hlen;
 144         __be32 saddr;
 145         int err;
 146
 147         if (unlikely(!OVS_CB(skb)->egress_tun_info)) {
 148                 err = -EINVAL;
 149                 goto err_free_skb;
 150         }
 151
 152         tun_key = &OVS_CB(skb)->egress_tun_info->tunnel;
 153         saddr = tun_key->ipv4_src;
 154         rt = find_route(ovs_dp_get_net(vport->dp),
 155                         &saddr, tun_key->ipv4_dst,
 156                         IPPROTO_GRE, tun_key->ipv4_tos,
 157                         skb->mark);
 158         if (IS_ERR(rt)) {
 159                 err = PTR_ERR(rt);
 160                 goto err_free_skb;
 161         }
 162
 163         tunnel_hlen = ip_gre_calc_hlen(tun_key->tun_flags);
 164
 165         min_headroom = LL_RESERVED_SPACE(rt_dst(rt).dev) + rt_dst(rt).header_len
 166                         + tunnel_hlen + sizeof(struct iphdr)
 167                         + (skb_vlan_tag_present(skb) ? VLAN_HLEN : 0);
 168         if (skb_headroom(skb) < min_headroom || skb_header_cloned(skb)) {
 169                 int head_delta = SKB_DATA_ALIGN(min_headroom -
 170                                                 skb_headroom(skb) +
 171                                                 16);
 172                 err = pskb_expand_head(skb, max_t(int, head_delta, 0),
 173                                         0, GFP_ATOMIC);
 174                 if (unlikely(err))
 175                         goto err_free_rt;
 176         }
 177
 178         skb = vlan_hwaccel_push_inside(skb);
 179         if (unlikely(!skb)) {
 180                 err = -ENOMEM;
 181                 goto err_free_rt;
 182         }
 183
 184         /* Push Tunnel header. */
 185         skb = __build_header(skb, tunnel_hlen);
 186         if (IS_ERR(skb)) {
 187                 err = PTR_ERR(skb);
 188                 skb = NULL;
 189                 goto err_free_rt;
 190         }
 191
 192         df = tun_key->tun_flags & TUNNEL_DONT_FRAGMENT ?
 193                 htons(IP_DF) : 0;
 194
 195         skb->ignore_df = 1;
 196
 197         return iptunnel_xmit(skb->sk, rt, skb, saddr,
 198                              tun_key->ipv4_dst, IPPROTO_GRE,
 199                              tun_key->ipv4_tos, tun_key->ipv4_ttl, df, false);
 200 err_free_rt:
 201         ip_rt_put(rt);
 202 err_free_skb:
 203         kfree_skb(skb);
 204         return err;
 205 }
 206
 207 static struct gre_cisco_protocol gre_protocol = {
 208         .handler        = gre_rcv,
 209         .err_handler    = gre_err,
 210         .priority       = 1,
 211 };
 212
 213 static int gre_ports;
 214 static int gre_init(void)
 215 {
 216         int err;
 217
 218         gre_ports++;
 219         if (gre_ports > 1)
 220                 return 0;
 221
 222         err = gre_cisco_register(&gre_protocol);
 223         if (err)
 224                 pr_warn("cannot register gre protocol handler\n");
 225
 226         return err;
 227 }
 228
 229 static void gre_exit(void)
 230 {
 231         gre_ports--;
 232         if (gre_ports > 0)
 233                 return;
 234
 235         gre_cisco_unregister(&gre_protocol);
 236 }
 237
 238 static const char *gre_get_name(const struct vport *vport)
 239 {
 240         return vport_priv(vport);
 241 }
 242
 243 static struct vport *gre_create(const struct vport_parms *parms)
 244 {
 245         struct net *net = ovs_dp_get_net(parms->dp);
 246         struct ovs_net *ovs_net;
 247         struct vport *vport;
 248         int err;
 249
 250         err = gre_init();
 251         if (err)
 252                 return ERR_PTR(err);
 253
 254         ovs_net = net_generic(net, ovs_net_id);
 255         if (ovsl_dereference(ovs_net->vport_net.gre_vport)) {
 256                 vport = ERR_PTR(-EEXIST);
 257                 goto error;
 258         }
 259
 260         vport = ovs_vport_alloc(IFNAMSIZ, &ovs_gre_vport_ops, parms);
 261         if (IS_ERR(vport))
 262                 goto error;
 263
 264         strncpy(vport_priv(vport), parms->name, IFNAMSIZ);
 265         rcu_assign_pointer(ovs_net->vport_net.gre_vport, vport);
 266         return vport;
 267
 268 error:
 269         gre_exit();
 270         return vport;
 271 }
 272
 273 static void gre_tnl_destroy(struct vport *vport)
 274 {
 275         struct net *net = ovs_dp_get_net(vport->dp);
 276         struct ovs_net *ovs_net;
 277
 278         ovs_net = net_generic(net, ovs_net_id);
 279
 280         RCU_INIT_POINTER(ovs_net->vport_net.gre_vport, NULL);
 281         ovs_vport_deferred_free(vport);
 282         gre_exit();
 283 }
 284
 285 static int gre_get_egress_tun_info(struct vport *vport, struct sk_buff *skb,
 286                                    struct ovs_tunnel_info *egress_tun_info)
 287 {
 288         return ovs_tunnel_get_egress_info(egress_tun_info,
 289                                           ovs_dp_get_net(vport->dp),
 290                                           OVS_CB(skb)->egress_tun_info,
 291                                           IPPROTO_GRE, skb->mark, 0, 0);
 292 }
 293
 294 static struct vport_ops ovs_gre_vport_ops = {
 295         .type           = OVS_VPORT_TYPE_GRE,
 296         .create         = gre_create,
 297         .destroy        = gre_tnl_destroy,
 298         .get_name       = gre_get_name,
 299         .send           = gre_tnl_send,
 300         .get_egress_tun_info    = gre_get_egress_tun_info,
 301         .owner          = THIS_MODULE,
 302 };
 303
 304 static int __init ovs_gre_tnl_init(void)
 305 {
 306         return ovs_vport_ops_register(&ovs_gre_vport_ops);
 307 }
 308
 309 static void __exit ovs_gre_tnl_exit(void)
 310 {
 311         ovs_vport_ops_unregister(&ovs_gre_vport_ops);
 312 }
 313
 314 module_init(ovs_gre_tnl_init);
 315 module_exit(ovs_gre_tnl_exit);
 316
 317 MODULE_DESCRIPTION("OVS: GRE switching port");
 318 MODULE_LICENSE("GPL");
 319 MODULE_ALIAS("vport-type-3");
 320 #endif