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         if (iptunnel_pull_header(skb, 0, tpi.proto))
 194                 goto drop;
 195
 196         iph = ip_hdr(skb);
 197         tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY,
 198                         iph->saddr, iph->daddr, 0);
 199         if (tunnel) {
 200                 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb))
 201                         goto drop;
 202                 return ip_tunnel_rcv(tunnel, skb, &tpi, log_ecn_error);
 203         }
 204
 205         return -1;
 206
 207 drop:
 208         kfree_skb(skb);
 209         return 0;
 210 }
 211
 212 /*
 213  *      This function assumes it is being called from dev_queue_xmit()
 214  *      and that skb is filled properly by that function.
 215  */
 216 static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev)
 217 {
 218         struct ip_tunnel *tunnel = netdev_priv(dev);
 219         const struct iphdr  *tiph = &tunnel->parms.iph;
 220
 221         if (unlikely(skb->protocol != htons(ETH_P_IP)))
 222                 goto tx_error;
 223
 224         if (likely(!skb->encapsulation)) {
 225                 skb_reset_inner_headers(skb);
 226                 skb->encapsulation = 1;
 227         }
 228
 229         ip_tunnel_xmit(skb, dev, tiph, tiph->protocol);
 230         return NETDEV_TX_OK;
 231
 232 tx_error:
 233         dev->stats.tx_errors++;
 234         dev_kfree_skb(skb);
 235         return NETDEV_TX_OK;
 236 }
 237
 238 static int
 239 ipip_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 240 {
 241         int err = 0;
 242         struct ip_tunnel_parm p;
 243
 244         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 245                 return -EFAULT;
 246
 247         if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
 248                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP ||
 249                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 250                         return -EINVAL;
 251         }
 252
 253         p.i_key = p.o_key = p.i_flags = p.o_flags = 0;
 254         if (p.iph.ttl)
 255                 p.iph.frag_off |= htons(IP_DF);
 256
 257         err = ip_tunnel_ioctl(dev, &p, cmd);
 258         if (err)
 259                 return err;
 260
 261         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 262                 return -EFAULT;
 263
 264         return 0;
 265 }
 266
 267 static const struct net_device_ops ipip_netdev_ops = {
 268         .ndo_init       = ipip_tunnel_init,
 269         .ndo_uninit     = ip_tunnel_uninit,
 270         .ndo_start_xmit = ipip_tunnel_xmit,
 271         .ndo_do_ioctl   = ipip_tunnel_ioctl,
 272         .ndo_change_mtu = ip_tunnel_change_mtu,
 273         .ndo_get_stats64 = ip_tunnel_get_stats64,
 274 };
 275
 276 #define IPIP_FEATURES (NETIF_F_SG |             \
 277                        NETIF_F_FRAGLIST |       \
 278                        NETIF_F_HIGHDMA |        \
 279                        NETIF_F_HW_CSUM)
 280
 281 static void ipip_tunnel_setup(struct net_device *dev)
 282 {
 283         dev->netdev_ops         = &ipip_netdev_ops;
 284
 285         dev->type               = ARPHRD_TUNNEL;
 286         dev->flags              = IFF_NOARP;
 287         dev->iflink             = 0;
 288         dev->addr_len           = 4;
 289         dev->features           |= NETIF_F_NETNS_LOCAL;
 290         dev->features           |= NETIF_F_LLTX;
 291         dev->priv_flags         &= ~IFF_XMIT_DST_RELEASE;
 292
 293         dev->features           |= IPIP_FEATURES;
 294         dev->hw_features        |= IPIP_FEATURES;
 295         ip_tunnel_setup(dev, ipip_net_id);
 296 }
 297
 298 static int ipip_tunnel_init(struct net_device *dev)
 299 {
 300         struct ip_tunnel *tunnel = netdev_priv(dev);
 301
 302         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
 303         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 304
 305         tunnel->hlen = 0;
 306         tunnel->parms.iph.protocol = IPPROTO_IPIP;
 307         return ip_tunnel_init(dev);
 308 }
 309
 310 static void ipip_netlink_parms(struct nlattr *data[],
 311                                struct ip_tunnel_parm *parms)
 312 {
 313         memset(parms, 0, sizeof(*parms));
 314
 315         parms->iph.version = 4;
 316         parms->iph.protocol = IPPROTO_IPIP;
 317         parms->iph.ihl = 5;
 318
 319         if (!data)
 320                 return;
 321
 322         if (data[IFLA_IPTUN_LINK])
 323                 parms->link = nla_get_u32(data[IFLA_IPTUN_LINK]);
 324
 325         if (data[IFLA_IPTUN_LOCAL])
 326                 parms->iph.saddr = nla_get_be32(data[IFLA_IPTUN_LOCAL]);
 327
 328         if (data[IFLA_IPTUN_REMOTE])
 329                 parms->iph.daddr = nla_get_be32(data[IFLA_IPTUN_REMOTE]);
 330
 331         if (data[IFLA_IPTUN_TTL]) {
 332                 parms->iph.ttl = nla_get_u8(data[IFLA_IPTUN_TTL]);
 333                 if (parms->iph.ttl)
 334                         parms->iph.frag_off = htons(IP_DF);
 335         }
 336
 337         if (data[IFLA_IPTUN_TOS])
 338                 parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]);
 339
 340         if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC]))
 341                 parms->iph.frag_off = htons(IP_DF);
 342 }
 343
 344 static int ipip_newlink(struct net *src_net, struct net_device *dev,
 345                         struct nlattr *tb[], struct nlattr *data[])
 346 {
 347         struct ip_tunnel_parm p;
 348
 349         ipip_netlink_parms(data, &p);
 350         return ip_tunnel_newlink(dev, tb, &p);
 351 }
 352
 353 static int ipip_changelink(struct net_device *dev, struct nlattr *tb[],
 354                            struct nlattr *data[])
 355 {
 356         struct ip_tunnel_parm p;
 357
 358         ipip_netlink_parms(data, &p);
 359
 360         if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) ||
 361             (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr))
 362                 return -EINVAL;
 363
 364         return ip_tunnel_changelink(dev, tb, &p);
 365 }
 366
 367 static size_t ipip_get_size(const struct net_device *dev)
 368 {
 369         return
 370                 /* IFLA_IPTUN_LINK */
 371                 nla_total_size(4) +
 372                 /* IFLA_IPTUN_LOCAL */
 373                 nla_total_size(4) +
 374                 /* IFLA_IPTUN_REMOTE */
 375                 nla_total_size(4) +
 376                 /* IFLA_IPTUN_TTL */
 377                 nla_total_size(1) +
 378                 /* IFLA_IPTUN_TOS */
 379                 nla_total_size(1) +
 380                 /* IFLA_IPTUN_PMTUDISC */
 381                 nla_total_size(1) +
 382                 0;
 383 }
 384
 385 static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev)
 386 {
 387         struct ip_tunnel *tunnel = netdev_priv(dev);
 388         struct ip_tunnel_parm *parm = &tunnel->parms;
 389
 390         if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) ||
 391             nla_put_be32(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) ||
 392             nla_put_be32(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) ||
 393             nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) ||
 394             nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) ||
 395             nla_put_u8(skb, IFLA_IPTUN_PMTUDISC,
 396                        !!(parm->iph.frag_off & htons(IP_DF))))
 397                 goto nla_put_failure;
 398         return 0;
 399
 400 nla_put_failure:
 401         return -EMSGSIZE;
 402 }
 403
 404 static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = {
 405         [IFLA_IPTUN_LINK]               = { .type = NLA_U32 },
 406         [IFLA_IPTUN_LOCAL]              = { .type = NLA_U32 },
 407         [IFLA_IPTUN_REMOTE]             = { .type = NLA_U32 },
 408         [IFLA_IPTUN_TTL]                = { .type = NLA_U8 },
 409         [IFLA_IPTUN_TOS]                = { .type = NLA_U8 },
 410         [IFLA_IPTUN_PMTUDISC]           = { .type = NLA_U8 },
 411 };
 412
 413 static struct rtnl_link_ops ipip_link_ops __read_mostly = {
 414         .kind           = "ipip",
 415         .maxtype        = IFLA_IPTUN_MAX,
 416         .policy         = ipip_policy,
 417         .priv_size      = sizeof(struct ip_tunnel),
 418         .setup          = ipip_tunnel_setup,
 419         .newlink        = ipip_newlink,
 420         .changelink     = ipip_changelink,
 421         .dellink        = ip_tunnel_dellink,
 422         .get_size       = ipip_get_size,
 423         .fill_info      = ipip_fill_info,
 424 };
 425
 426 static struct xfrm_tunnel ipip_handler __read_mostly = {
 427         .handler        =       ipip_rcv,
 428         .err_handler    =       ipip_err,
 429         .priority       =       1,
 430 };
 431
 432 static int __net_init ipip_init_net(struct net *net)
 433 {
 434         return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0");
 435 }
 436
 437 static void __net_exit ipip_exit_net(struct net *net)
 438 {
 439         struct ip_tunnel_net *itn = net_generic(net, ipip_net_id);
 440         ip_tunnel_delete_net(itn);
 441 }
 442
 443 static struct pernet_operations ipip_net_ops = {
 444         .init = ipip_init_net,
 445         .exit = ipip_exit_net,
 446         .id   = &ipip_net_id,
 447         .size = sizeof(struct ip_tunnel_net),
 448 };
 449
 450 static int __init ipip_init(void)
 451 {
 452         int err;
 453
 454         pr_info("ipip: IPv4 over IPv4 tunneling driver\n");
 455
 456         err = register_pernet_device(&ipip_net_ops);
 457         if (err < 0)
 458                 return err;
 459         err = xfrm4_tunnel_register(&ipip_handler, AF_INET);
 460         if (err < 0) {
 461                 pr_info("%s: can't register tunnel\n", __func__);
 462                 goto xfrm_tunnel_failed;
 463         }
 464         err = rtnl_link_register(&ipip_link_ops);
 465         if (err < 0)
 466                 goto rtnl_link_failed;
 467
 468 out:
 469         return err;
 470
 471 rtnl_link_failed:
 472         xfrm4_tunnel_deregister(&ipip_handler, AF_INET);
 473 xfrm_tunnel_failed:
 474         unregister_pernet_device(&ipip_net_ops);
 475         goto out;
 476 }
 477
 478 static void __exit ipip_fini(void)
 479 {
 480         rtnl_link_unregister(&ipip_link_ops);
 481         if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET))
 482                 pr_info("%s: can't deregister tunnel\n", __func__);
 483
 484         unregister_pernet_device(&ipip_net_ops);
 485 }
 486
 487 module_init(ipip_init);
 488 module_exit(ipip_fini);
 489 MODULE_LICENSE("GPL");
 490 MODULE_ALIAS_NETDEV("tunl0");