net/ipv4/ipip.c

   1 /*
   2  *      Linux NET3:     IP/IP protocol decoder.
   3  *
   4  *      Authors:
   5  *              Sam Lantinga (slouken@cs.ucdavis.edu)  02/01/95
   6  *
   7  *      Fixes:
   8  *              Alan Cox        :       Merged and made usable non modular (its so tiny its silly as
   9  *                                      a module taking up 2 pages).
  10  *              Alan Cox        :       Fixed bug with 1.3.18 and IPIP not working (now needs to set skb->h.iph)
  11  *                                      to keep ip_forward happy.
  12  *              Alan Cox        :       More fixes for 1.3.21, and firewall fix. Maybe this will work soon 8).
  13  *              Kai Schulte     :       Fixed #defines for IP_FIREWALL->FIREWALL
  14  *              David Woodhouse :       Perform some basic ICMP handling.
  15  *                                      IPIP Routing without decapsulation.
  16  *              Carlos Picoto   :       GRE over IP support
  17  *              Alexey Kuznetsov:       Reworked. Really, now it is truncated version of ipv4/ip_gre.c.
  18  *                                      I do not want to merge them together.
  19  *
  20  *      This program is free software; you can redistribute it and/or
  21  *      modify it under the terms of the GNU General Public License
  22  *      as published by the Free Software Foundation; either version
  23  *      2 of the License, or (at your option) any later version.
  24  *
  25  */
  26
  27 /* tunnel.c: an IP tunnel driver
  28
  29         The purpose of this driver is to provide an IP tunnel through
  30         which you can tunnel network traffic transparently across subnets.
  31
  32         This was written by looking at Nick Holloway's dummy driver
  33         Thanks for the great code!
  34
  35                 -Sam Lantinga   (slouken@cs.ucdavis.edu)  02/01/95
  36
  37         Minor tweaks:
  38                 Cleaned up the code a little and added some pre-1.3.0 tweaks.
  39                 dev->hard_header/hard_header_len changed to use no headers.
  40                 Comments/bracketing tweaked.
  41                 Made the tunnels use dev->name not tunnel: when error reporting.
  42                 Added tx_dropped stat
  43
  44                 -Alan Cox       (alan@lxorguk.ukuu.org.uk) 21 March 95
  45
  46         Reworked:
  47                 Changed to tunnel to destination gateway in addition to the
  48                         tunnel's pointopoint address
  49                 Almost completely rewritten
  50                 Note:  There is currently no firewall or ICMP handling done.
  51
  52                 -Sam Lantinga   (slouken@cs.ucdavis.edu) 02/13/96
  53
  54 */
  55
  56 /* Things I wish I had known when writing the tunnel driver:
  57
  58         When the tunnel_xmit() function is called, the skb contains the
  59         packet to be sent (plus a great deal of extra info), and dev
  60         contains the tunnel device that _we_ are.
  61
  62         When we are passed a packet, we are expected to fill in the
  63         source address with our source IP address.
  64
  65         What is the proper way to allocate, copy and free a buffer?
  66         After you allocate it, it is a "0 length" chunk of memory
  67         starting at zero.  If you want to add headers to the buffer
  68         later, you'll have to call "skb_reserve(skb, amount)" with
  69         the amount of memory you want reserved.  Then, you call
  70         "skb_put(skb, amount)" with the amount of space you want in
  71         the buffer.  skb_put() returns a pointer to the top (#0) of
  72         that buffer.  skb->len is set to the amount of space you have
  73         "allocated" with skb_put().  You can then write up to skb->len
  74         bytes to that buffer.  If you need more, you can call skb_put()
  75         again with the additional amount of space you need.  You can
  76         find out how much more space you can allocate by calling
  77         "skb_tailroom(skb)".
  78         Now, to add header space, call "skb_push(skb, header_len)".
  79         This creates space at the beginning of the buffer and returns
  80         a pointer to this new space.  If later you need to strip a
  81         header from a buffer, call "skb_pull(skb, header_len)".
  82         skb_headroom() will return how much space is left at the top
  83         of the buffer (before the main data).  Remember, this headroom
  84         space must be reserved before the skb_put() function is called.
  85         */
  86
  87 /*
  88    This version of net/ipv4/ipip.c is cloned of net/ipv4/ip_gre.c
  89
  90    For comments look at net/ipv4/ip_gre.c --ANK
  91  */
  92
  93
  94 #include <linux/capability.h>
  95 #include <linux/module.h>
  96 #include <linux/types.h>
  97 #include <linux/kernel.h>
  98 #include <linux/slab.h>
  99 #include <asm/uaccess.h>
 100 #include <linux/skbuff.h>
 101 #include <linux/netdevice.h>
 102 #include <linux/in.h>
 103 #include <linux/tcp.h>
 104 #include <linux/udp.h>
 105 #include <linux/if_arp.h>
 106 #include <linux/mroute.h>
 107 #include <linux/init.h>
 108 #include <linux/netfilter_ipv4.h>
 109 #include <linux/if_ether.h>
 110
 111 #include <net/sock.h>
 112 #include <net/ip.h>
 113 #include <net/icmp.h>
 114 #include <net/ip_tunnels.h>
 115 #include <net/inet_ecn.h>
 116 #include <net/xfrm.h>
 117 #include <net/net_namespace.h>
 118 #include <net/netns/generic.h>
 119
 120 static bool log_ecn_error = true;
 121 module_param(log_ecn_error, bool, 0644);
 122 MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN");
 123
 124 static int ipip_net_id __read_mostly;
 125
 126 static int ipip_tunnel_init(struct net_device *dev);
 127 static struct rtnl_link_ops ipip_link_ops __read_mostly;
 128
 129 static int ipip_err(struct sk_buff *skb, u32 info)
 130 {
 131
 132 /* All the routers (except for Linux) return only
 133    8 bytes of packet payload. It means, that precise relaying of
 134    ICMP in the real Internet is absolutely infeasible.
 135  */
 136         struct net *net = dev_net(skb->dev);
 137         struct ip_tunnel_net *itn = net_generic(net, ipip_net_id);
 138         const struct iphdr *iph = (const struct iphdr *)skb->data;
 139         struct ip_tunnel *t;
 140         int err;
 141         const int type = icmp_hdr(skb)->type;
 142         const int code = icmp_hdr(skb)->code;
 143
 144         err = -ENOENT;
 145         t = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY,
 146                              iph->daddr, iph->saddr, 0);
 147         if (t == NULL)
 148                 goto out;
 149
 150         if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) {
 151                 ipv4_update_pmtu(skb, dev_net(skb->dev), info,
 152                                  t->dev->ifindex, 0, IPPROTO_IPIP, 0);
 153                 err = 0;
 154                 goto out;
 155         }
 156
 157         if (type == ICMP_REDIRECT) {
 158                 ipv4_redirect(skb, dev_net(skb->dev), t->dev->ifindex, 0,
 159                               IPPROTO_IPIP, 0);
 160                 err = 0;
 161                 goto out;
 162         }
 163
 164         if (t->parms.iph.daddr == 0)
 165                 goto out;
 166
 167         err = 0;
 168         if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED)
 169                 goto out;
 170
 171         if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO))
 172                 t->err_count++;
 173         else
 174                 t->err_count = 1;
 175         t->err_time = jiffies;
 176
 177 out:
 178         return err;
 179 }
 180
 181 static const struct tnl_ptk_info tpi = {
 182         /* no tunnel info required for ipip. */
 183         .proto = htons(ETH_P_IP),
 184 };
 185
 186 static int ipip_rcv(struct sk_buff *skb)
 187 {
 188         struct net *net = dev_net(skb->dev);
 189         struct ip_tunnel_net *itn = net_generic(net, ipip_net_id);
 190         struct ip_tunnel *tunnel;
 191         const struct iphdr *iph;
 192
 193         iph = ip_hdr(skb);
 194         tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY,
 195                         iph->saddr, iph->daddr, 0);
 196         if (tunnel) {
 197                 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 198                         goto drop;
 199                 if (iptunnel_pull_header(skb, 0, tpi.proto))
 200                         goto drop;
 201                 return ip_tunnel_rcv(tunnel, skb, &tpi, log_ecn_error);
 202         }
 203
 204         return -1;
 205
 206 drop:
 207         kfree_skb(skb);
 208         return 0;
 209 }
 210
 211 /*
 212  *      This function assumes it is being called from dev_queue_xmit()
 213  *      and that skb is filled properly by that function.
 214  */
 215 static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 216 {
 217         struct ip_tunnel *tunnel = netdev_priv(dev);
 218         const struct iphdr  *tiph = &tunnel->parms.iph;
 219
 220         if (unlikely(skb->protocol != htons(ETH_P_IP)))
 221                 goto tx_error;
 222
 223         if (likely(!skb->encapsulation)) {
 224                 skb_reset_inner_headers(skb);
 225                 skb->encapsulation = 1;
 226         }
 227
 228         ip_tunnel_xmit(skb, dev, tiph, tiph->protocol);
 229         return NETDEV_TX_OK;
 230
 231 tx_error:
 232         dev->stats.tx_errors++;
 233         dev_kfree_skb(skb);
 234         return NETDEV_TX_OK;
 235 }
 236
 237 static int
 238 ipip_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 239 {
 240         int err = 0;
 241         struct ip_tunnel_parm p;
 242
 243         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 244                 return -EFAULT;
 245
 246         if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
 247                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP ||
 248                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 249                         return -EINVAL;
 250         }
 251
 252         p.i_key = p.o_key = p.i_flags = p.o_flags = 0;
 253         if (p.iph.ttl)
 254                 p.iph.frag_off |= htons(IP_DF);
 255
 256         err = ip_tunnel_ioctl(dev, &p, cmd);
 257         if (err)
 258                 return err;
 259
 260         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 261                 return -EFAULT;
 262
 263         return 0;
 264 }
 265
 266 static const struct net_device_ops ipip_netdev_ops = {
 267         .ndo_init       = ipip_tunnel_init,
 268         .ndo_uninit     = ip_tunnel_uninit,
 269         .ndo_start_xmit = ipip_tunnel_xmit,
 270         .ndo_do_ioctl   = ipip_tunnel_ioctl,
 271         .ndo_change_mtu = ip_tunnel_change_mtu,
 272         .ndo_get_stats64 = ip_tunnel_get_stats64,
 273 };
 274
 275 #define IPIP_FEATURES (NETIF_F_SG |             \
 276                        NETIF_F_FRAGLIST |       \
 277                        NETIF_F_HIGHDMA |        \
 278                        NETIF_F_HW_CSUM)
 279
 280 static void ipip_tunnel_setup(struct net_device *dev)
 281 {
 282         dev->netdev_ops         = &ipip_netdev_ops;
 283
 284         dev->type               = ARPHRD_TUNNEL;
 285         dev->flags              = IFF_NOARP;
 286         dev->iflink             = 0;
 287         dev->addr_len           = 4;
 288         dev->features           |= NETIF_F_LLTX;
 289         dev->priv_flags         &= ~IFF_XMIT_DST_RELEASE;
 290
 291         dev->features           |= IPIP_FEATURES;
 292         dev->hw_features        |= IPIP_FEATURES;
 293         ip_tunnel_setup(dev, ipip_net_id);
 294 }
 295
 296 static int ipip_tunnel_init(struct net_device *dev)
 297 {
 298         struct ip_tunnel *tunnel = netdev_priv(dev);
 299
 300         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
 301         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 302
 303         tunnel->hlen = 0;
 304         tunnel->parms.iph.protocol = IPPROTO_IPIP;
 305         return ip_tunnel_init(dev);
 306 }
 307
 308 static void ipip_netlink_parms(struct nlattr *data[],
 309                                struct ip_tunnel_parm *parms)
 310 {
 311         memset(parms, 0, sizeof(*parms));
 312
 313         parms->iph.version = 4;
 314         parms->iph.protocol = IPPROTO_IPIP;
 315         parms->iph.ihl = 5;
 316
 317         if (!data)
 318                 return;
 319
 320         if (data[IFLA_IPTUN_LINK])
 321                 parms->link = nla_get_u32(data[IFLA_IPTUN_LINK]);
 322
 323         if (data[IFLA_IPTUN_LOCAL])
 324                 parms->iph.saddr = nla_get_be32(data[IFLA_IPTUN_LOCAL]);
 325
 326         if (data[IFLA_IPTUN_REMOTE])
 327                 parms->iph.daddr = nla_get_be32(data[IFLA_IPTUN_REMOTE]);
 328
 329         if (data[IFLA_IPTUN_TTL]) {
 330                 parms->iph.ttl = nla_get_u8(data[IFLA_IPTUN_TTL]);
 331                 if (parms->iph.ttl)
 332                         parms->iph.frag_off = htons(IP_DF);
 333         }
 334
 335         if (data[IFLA_IPTUN_TOS])
 336                 parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]);
 337
 338         if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC]))
 339                 parms->iph.frag_off = htons(IP_DF);
 340 }
 341
 342 static int ipip_newlink(struct net *src_net, struct net_device *dev,
 343                         struct nlattr *tb[], struct nlattr *data[])
 344 {
 345         struct ip_tunnel_parm p;
 346
 347         ipip_netlink_parms(data, &p);
 348         return ip_tunnel_newlink(dev, tb, &p);
 349 }
 350
 351 static int ipip_changelink(struct net_device *dev, struct nlattr *tb[],
 352                            struct nlattr *data[])
 353 {
 354         struct ip_tunnel_parm p;
 355
 356         ipip_netlink_parms(data, &p);
 357
 358         if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) ||
 359             (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr))
 360                 return -EINVAL;
 361
 362         return ip_tunnel_changelink(dev, tb, &p);
 363 }
 364
 365 static size_t ipip_get_size(const struct net_device *dev)
 366 {
 367         return
 368                 /* IFLA_IPTUN_LINK */
 369                 nla_total_size(4) +
 370                 /* IFLA_IPTUN_LOCAL */
 371                 nla_total_size(4) +
 372                 /* IFLA_IPTUN_REMOTE */
 373                 nla_total_size(4) +
 374                 /* IFLA_IPTUN_TTL */
 375                 nla_total_size(1) +
 376                 /* IFLA_IPTUN_TOS */
 377                 nla_total_size(1) +
 378                 /* IFLA_IPTUN_PMTUDISC */
 379                 nla_total_size(1) +
 380                 0;
 381 }
 382
 383 static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev)
 384 {
 385         struct ip_tunnel *tunnel = netdev_priv(dev);
 386         struct ip_tunnel_parm *parm = &tunnel->parms;
 387
 388         if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) ||
 389             nla_put_be32(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) ||
 390             nla_put_be32(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) ||
 391             nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) ||
 392             nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) ||
 393             nla_put_u8(skb, IFLA_IPTUN_PMTUDISC,
 394                        !!(parm->iph.frag_off & htons(IP_DF))))
 395                 goto nla_put_failure;
 396         return 0;
 397
 398 nla_put_failure:
 399         return -EMSGSIZE;
 400 }
 401
 402 static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = {
 403         [IFLA_IPTUN_LINK]               = { .type = NLA_U32 },
 404         [IFLA_IPTUN_LOCAL]              = { .type = NLA_U32 },
 405         [IFLA_IPTUN_REMOTE]             = { .type = NLA_U32 },
 406         [IFLA_IPTUN_TTL]                = { .type = NLA_U8 },
 407         [IFLA_IPTUN_TOS]                = { .type = NLA_U8 },
 408         [IFLA_IPTUN_PMTUDISC]           = { .type = NLA_U8 },
 409 };
 410
 411 static struct rtnl_link_ops ipip_link_ops __read_mostly = {
 412         .kind           = "ipip",
 413         .maxtype        = IFLA_IPTUN_MAX,
 414         .policy         = ipip_policy,
 415         .priv_size      = sizeof(struct ip_tunnel),
 416         .setup          = ipip_tunnel_setup,
 417         .newlink        = ipip_newlink,
 418         .changelink     = ipip_changelink,
 419         .dellink        = ip_tunnel_dellink,
 420         .get_size       = ipip_get_size,
 421         .fill_info      = ipip_fill_info,
 422 };
 423
 424 static struct xfrm_tunnel ipip_handler __read_mostly = {
 425         .handler        =       ipip_rcv,
 426         .err_handler    =       ipip_err,
 427         .priority       =       1,
 428 };
 429
 430 static int __net_init ipip_init_net(struct net *net)
 431 {
 432         return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0");
 433 }
 434
 435 static void __net_exit ipip_exit_net(struct net *net)
 436 {
 437         struct ip_tunnel_net *itn = net_generic(net, ipip_net_id);
 438         ip_tunnel_delete_net(itn, &ipip_link_ops);
 439 }
 440
 441 static struct pernet_operations ipip_net_ops = {
 442         .init = ipip_init_net,
 443         .exit = ipip_exit_net,
 444         .id   = &ipip_net_id,
 445         .size = sizeof(struct ip_tunnel_net),
 446 };
 447
 448 static int __init ipip_init(void)
 449 {
 450         int err;
 451
 452         pr_info("ipip: IPv4 over IPv4 tunneling driver\n");
 453
 454         err = register_pernet_device(&ipip_net_ops);
 455         if (err < 0)
 456                 return err;
 457         err = xfrm4_tunnel_register(&ipip_handler, AF_INET);
 458         if (err < 0) {
 459                 pr_info("%s: can't register tunnel\n", __func__);
 460                 goto xfrm_tunnel_failed;
 461         }
 462         err = rtnl_link_register(&ipip_link_ops);
 463         if (err < 0)
 464                 goto rtnl_link_failed;
 465
 466 out:
 467         return err;
 468
 469 rtnl_link_failed:
 470         xfrm4_tunnel_deregister(&ipip_handler, AF_INET);
 471 xfrm_tunnel_failed:
 472         unregister_pernet_device(&ipip_net_ops);
 473         goto out;
 474 }
 475
 476 static void __exit ipip_fini(void)
 477 {
 478         rtnl_link_unregister(&ipip_link_ops);
 479         if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET))
 480                 pr_info("%s: can't deregister tunnel\n", __func__);
 481
 482         unregister_pernet_device(&ipip_net_ops);
 483 }
 484
 485 module_init(ipip_init);
 486 module_exit(ipip_fini);
 487 MODULE_LICENSE("GPL");
 488 MODULE_ALIAS_NETDEV("tunl0");