datapath/vport-gre.c

   1 /*
   2  * Copyright (c) 2007-2012 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
  28 #include <net/icmp.h>
  29 #include <net/ip.h>
  30 #include <net/protocol.h>
  31
  32 #include "datapath.h"
  33 #include "tunnel.h"
  34 #include "vport.h"
  35
  36 /*
  37  * The GRE header is composed of a series of sections: a base and then a variable
  38  * number of options.
  39  */
  40 #define GRE_HEADER_SECTION 4
  41
  42 struct gre_base_hdr {
  43         __be16 flags;
  44         __be16 protocol;
  45 };
  46
  47 static int gre_hdr_len(const struct ovs_key_ipv4_tunnel *tun_key)
  48 {
  49         int len = GRE_HEADER_SECTION;
  50
  51         if (tun_key->tun_flags & OVS_TNL_F_KEY)
  52                 len += GRE_HEADER_SECTION;
  53         if (tun_key->tun_flags & OVS_TNL_F_CSUM)
  54                 len += GRE_HEADER_SECTION;
  55         return len;
  56 }
  57
  58 static int gre64_hdr_len(const struct ovs_key_ipv4_tunnel *tun_key)
  59 {
  60         /* Set key for GRE64 tunnels, even when key if is zero. */
  61         int len = GRE_HEADER_SECTION +          /* GRE Hdr */
  62                   GRE_HEADER_SECTION +          /* GRE Key */
  63                   GRE_HEADER_SECTION;           /* GRE SEQ */
  64
  65         if (tun_key->tun_flags & OVS_TNL_F_CSUM)
  66                 len += GRE_HEADER_SECTION;
  67
  68         return len;
  69 }
  70
  71 /* Returns the least-significant 32 bits of a __be64. */
  72 static __be32 be64_get_low32(__be64 x)
  73 {
  74 #ifdef __BIG_ENDIAN
  75         return (__force __be32)x;
  76 #else
  77         return (__force __be32)((__force u64)x >> 32);
  78 #endif
  79 }
  80
  81 static __be32 be64_get_high32(__be64 x)
  82 {
  83 #ifdef __BIG_ENDIAN
  84         return (__force __be32)((__force u64)x >> 32);
  85 #else
  86         return (__force __be32)x;
  87 #endif
  88 }
  89
  90 static void __gre_build_header(struct sk_buff *skb,
  91                                int tunnel_hlen,
  92                                bool is_gre64)
  93 {
  94         const struct ovs_key_ipv4_tunnel *tun_key = OVS_CB(skb)->tun_key;
  95         __be32 *options = (__be32 *)(skb_network_header(skb) + tunnel_hlen
  96                         - GRE_HEADER_SECTION);
  97         struct gre_base_hdr *greh = (struct gre_base_hdr *) skb_transport_header(skb);
  98         greh->protocol = htons(ETH_P_TEB);
  99         greh->flags = 0;
 100
 101         /* Work backwards over the options so the checksum is last. */
 102         if (tun_key->tun_flags & OVS_TNL_F_KEY || is_gre64) {
 103                 greh->flags |= GRE_KEY;
 104                 if (is_gre64) {
 105                         /* Set higher 32 bits to seq. */
 106                         *options = be64_get_high32(tun_key->tun_id);
 107                         options--;
 108                         greh->flags |= GRE_SEQ;
 109                 }
 110                 *options = be64_get_low32(tun_key->tun_id);
 111                 options--;
 112         }
 113
 114         if (tun_key->tun_flags & OVS_TNL_F_CSUM) {
 115                 greh->flags |= GRE_CSUM;
 116                 *options = 0;
 117                 *(__sum16 *)options = csum_fold(skb_checksum(skb,
 118                                                 skb_transport_offset(skb),
 119                                                 skb->len - skb_transport_offset(skb),
 120                                                 0));
 121         }
 122 }
 123
 124 static void gre_build_header(const struct vport *vport,
 125                              struct sk_buff *skb,
 126                              int tunnel_hlen)
 127 {
 128         __gre_build_header(skb, tunnel_hlen, false);
 129 }
 130
 131 static void gre64_build_header(const struct vport *vport,
 132                                struct sk_buff *skb,
 133                                int tunnel_hlen)
 134 {
 135         __gre_build_header(skb, tunnel_hlen, true);
 136 }
 137
 138 static __be64 key_to_tunnel_id(__be32 key, __be32 seq)
 139 {
 140 #ifdef __BIG_ENDIAN
 141         return (__force __be64)((__force u64)seq << 32 | (__force u32)key);
 142 #else
 143         return (__force __be64)((__force u64)key << 32 | (__force u32)seq);
 144 #endif
 145 }
 146
 147 static int parse_header(struct iphdr *iph, __be16 *flags, __be64 *tun_id,
 148                         bool *is_gre64)
 149 {
 150         /* IP and ICMP protocol handlers check that the IHL is valid. */
 151         struct gre_base_hdr *greh = (struct gre_base_hdr *)((u8 *)iph + (iph->ihl << 2));
 152         __be32 *options = (__be32 *)(greh + 1);
 153         int hdr_len;
 154
 155         *flags = greh->flags;
 156
 157         if (unlikely(greh->flags & (GRE_VERSION | GRE_ROUTING)))
 158                 return -EINVAL;
 159
 160         if (unlikely(greh->protocol != htons(ETH_P_TEB)))
 161                 return -EINVAL;
 162
 163         hdr_len = GRE_HEADER_SECTION;
 164
 165         if (greh->flags & GRE_CSUM) {
 166                 hdr_len += GRE_HEADER_SECTION;
 167                 options++;
 168         }
 169
 170         if (greh->flags & GRE_KEY) {
 171                 __be32 seq;
 172                 __be32 gre_key;
 173
 174                 gre_key = *options;
 175                 hdr_len += GRE_HEADER_SECTION;
 176                 options++;
 177
 178                 if (greh->flags & GRE_SEQ) {
 179                         seq = *options;
 180                         *is_gre64 = true;
 181                 } else {
 182                         seq = 0;
 183                         *is_gre64 = false;
 184                 }
 185                 *tun_id = key_to_tunnel_id(gre_key, seq);
 186         } else {
 187                 *tun_id = 0;
 188                 /* Ignore GRE seq if there is no key present. */
 189                 *is_gre64 = false;
 190         }
 191
 192         if (greh->flags & GRE_SEQ)
 193                 hdr_len += GRE_HEADER_SECTION;
 194
 195         return hdr_len;
 196 }
 197
 198 static bool check_checksum(struct sk_buff *skb)
 199 {
 200         struct iphdr *iph = ip_hdr(skb);
 201         struct gre_base_hdr *greh = (struct gre_base_hdr *)(iph + 1);
 202         __sum16 csum = 0;
 203
 204         if (greh->flags & GRE_CSUM) {
 205                 switch (skb->ip_summed) {
 206                 case CHECKSUM_COMPLETE:
 207                         csum = csum_fold(skb->csum);
 208
 209                         if (!csum)
 210                                 break;
 211                         /* Fall through. */
 212
 213                 case CHECKSUM_NONE:
 214                         skb->csum = 0;
 215                         csum = __skb_checksum_complete(skb);
 216                         skb->ip_summed = CHECKSUM_COMPLETE;
 217                         break;
 218                 }
 219         }
 220
 221         return (csum == 0);
 222 }
 223
 224 static u32 gre_flags_to_tunnel_flags(__be16 gre_flags, bool is_gre64)
 225 {
 226         u32 tunnel_flags = 0;
 227
 228         if (gre_flags & GRE_KEY || is_gre64)
 229                 tunnel_flags = OVS_TNL_F_KEY;
 230
 231         if (gre_flags & GRE_CSUM)
 232                 tunnel_flags |= OVS_TNL_F_CSUM;
 233
 234         return tunnel_flags;
 235 }
 236
 237 /* Called with rcu_read_lock and BH disabled. */
 238 static int gre_rcv(struct sk_buff *skb)
 239 {
 240         struct ovs_net *ovs_net;
 241         struct vport *vport;
 242         int hdr_len;
 243         struct iphdr *iph;
 244         struct ovs_key_ipv4_tunnel tun_key;
 245         __be16 gre_flags;
 246         u32 tnl_flags;
 247         __be64 key;
 248         bool is_gre64;
 249
 250         if (unlikely(!pskb_may_pull(skb, sizeof(struct gre_base_hdr) + ETH_HLEN)))
 251                 goto error;
 252         if (unlikely(!check_checksum(skb)))
 253                 goto error;
 254
 255         hdr_len = parse_header(ip_hdr(skb), &gre_flags, &key, &is_gre64);
 256         if (unlikely(hdr_len < 0))
 257                 goto error;
 258
 259         ovs_net = net_generic(dev_net(skb->dev), ovs_net_id);
 260         if (is_gre64)
 261                 vport = rcu_dereference(ovs_net->vport_net.gre64_vport);
 262         else
 263                 vport = rcu_dereference(ovs_net->vport_net.gre_vport);
 264         if (unlikely(!vport))
 265                 goto error;
 266
 267         if (unlikely(!pskb_may_pull(skb, hdr_len + ETH_HLEN)))
 268                 goto error;
 269
 270         iph = ip_hdr(skb);
 271         tnl_flags = gre_flags_to_tunnel_flags(gre_flags, is_gre64);
 272         tnl_tun_key_init(&tun_key, iph, key, tnl_flags);
 273
 274         skb_pull_rcsum(skb, hdr_len);
 275
 276         ovs_tnl_rcv(vport, skb, &tun_key);
 277         return 0;
 278
 279 error:
 280         kfree_skb(skb);
 281         return 0;
 282 }
 283
 284 static const struct net_protocol gre_protocol_handlers = {
 285         .handler        =       gre_rcv,
 286 #if LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,32)
 287         .netns_ok       =       1,
 288 #endif
 289 };
 290
 291 static int gre_ports;
 292 static int gre_init(void)
 293 {
 294         int err;
 295
 296         gre_ports++;
 297         if (gre_ports > 1)
 298                 return 0;
 299
 300         err = inet_add_protocol(&gre_protocol_handlers, IPPROTO_GRE);
 301         if (err)
 302                 pr_warn("cannot register gre protocol handler\n");
 303
 304         return err;
 305 }
 306
 307 static void gre_exit(void)
 308 {
 309         gre_ports--;
 310         if (gre_ports > 0)
 311                 return;
 312
 313         inet_del_protocol(&gre_protocol_handlers, IPPROTO_GRE);
 314 }
 315
 316 static const char *gre_get_name(const struct vport *vport)
 317 {
 318         return vport_priv(vport);
 319 }
 320
 321 static struct vport *gre_create(const struct vport_parms *parms)
 322 {
 323         struct net *net = ovs_dp_get_net(parms->dp);
 324         struct ovs_net *ovs_net;
 325         struct vport *vport;
 326         int err;
 327
 328         err = gre_init();
 329         if (err)
 330                 return ERR_PTR(err);
 331
 332         ovs_net = net_generic(net, ovs_net_id);
 333         if (ovsl_dereference(ovs_net->vport_net.gre_vport)) {
 334                 vport = ERR_PTR(-EEXIST);
 335                 goto error;
 336         }
 337
 338         vport = ovs_vport_alloc(IFNAMSIZ, &ovs_gre_vport_ops, parms);
 339         if (IS_ERR(vport))
 340                 goto error;
 341
 342         strncpy(vport_priv(vport), parms->name, IFNAMSIZ);
 343         rcu_assign_pointer(ovs_net->vport_net.gre_vport, vport);
 344         return vport;
 345
 346 error:
 347         gre_exit();
 348         return vport;
 349 }
 350
 351 static void gre_tnl_destroy(struct vport *vport)
 352 {
 353         struct net *net = ovs_dp_get_net(vport->dp);
 354         struct ovs_net *ovs_net;
 355
 356         ovs_net = net_generic(net, ovs_net_id);
 357
 358         rcu_assign_pointer(ovs_net->vport_net.gre_vport, NULL);
 359         ovs_vport_deferred_free(vport);
 360         gre_exit();
 361 }
 362
 363 static int gre_tnl_send(struct vport *vport, struct sk_buff *skb)
 364 {
 365         int hlen;
 366
 367         if (unlikely(!OVS_CB(skb)->tun_key))
 368                 return -EINVAL;
 369
 370         hlen = gre_hdr_len(OVS_CB(skb)->tun_key);
 371         return ovs_tnl_send(vport, skb, IPPROTO_GRE, hlen, gre_build_header);
 372 }
 373
 374 const struct vport_ops ovs_gre_vport_ops = {
 375         .type           = OVS_VPORT_TYPE_GRE,
 376         .create         = gre_create,
 377         .destroy        = gre_tnl_destroy,
 378         .get_name       = gre_get_name,
 379         .send           = gre_tnl_send,
 380 };
 381
 382 /* GRE64 vport. */
 383 static struct vport *gre64_create(const struct vport_parms *parms)
 384 {
 385         struct net *net = ovs_dp_get_net(parms->dp);
 386         struct ovs_net *ovs_net;
 387         struct vport *vport;
 388         int err;
 389
 390         err = gre_init();
 391         if (err)
 392                 return ERR_PTR(err);
 393
 394         ovs_net = net_generic(net, ovs_net_id);
 395         if (ovsl_dereference(ovs_net->vport_net.gre64_vport)) {
 396                 vport = ERR_PTR(-EEXIST);
 397                 goto error;
 398         }
 399
 400         vport = ovs_vport_alloc(IFNAMSIZ, &ovs_gre64_vport_ops, parms);
 401         if (IS_ERR(vport))
 402                 goto error;
 403
 404         strncpy(vport_priv(vport), parms->name, IFNAMSIZ);
 405         rcu_assign_pointer(ovs_net->vport_net.gre64_vport, vport);
 406         return vport;
 407 error:
 408         gre_exit();
 409         return vport;
 410 }
 411
 412 static void gre64_tnl_destroy(struct vport *vport)
 413 {
 414         struct net *net = ovs_dp_get_net(vport->dp);
 415         struct ovs_net *ovs_net;
 416
 417         ovs_net = net_generic(net, ovs_net_id);
 418
 419         rcu_assign_pointer(ovs_net->vport_net.gre64_vport, NULL);
 420         ovs_vport_deferred_free(vport);
 421         gre_exit();
 422 }
 423
 424 static int gre64_tnl_send(struct vport *vport, struct sk_buff *skb)
 425 {
 426         int hlen;
 427
 428         if (unlikely(!OVS_CB(skb)->tun_key))
 429                 return -EINVAL;
 430
 431         hlen = gre64_hdr_len(OVS_CB(skb)->tun_key);
 432         return ovs_tnl_send(vport, skb, IPPROTO_GRE, hlen, gre64_build_header);
 433 }
 434
 435 const struct vport_ops ovs_gre64_vport_ops = {
 436         .type           = OVS_VPORT_TYPE_GRE64,
 437         .create         = gre64_create,
 438         .destroy        = gre64_tnl_destroy,
 439         .get_name       = gre_get_name,
 440         .send           = gre64_tnl_send,
 441 };