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->parms.link, 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->parms.link, 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         skb = iptunnel_handle_offloads(skb, false, SKB_GSO_IPIP);
 224         if (IS_ERR(skb))
 225                 goto out;
 226
 227         skb_set_inner_ipproto(skb, IPPROTO_IPIP);
 228
 229         ip_tunnel_xmit(skb, dev, tiph, tiph->protocol);
 230         return NETDEV_TX_OK;
 231
 232 tx_error:
 233         kfree_skb(skb);
 234 out:
 235         dev->stats.tx_errors++;
 236         return NETDEV_TX_OK;
 237 }
 238
 239 static int
 240 ipip_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
 241 {
 242         int err = 0;
 243         struct ip_tunnel_parm p;
 244
 245         if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p)))
 246                 return -EFAULT;
 247
 248         if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) {
 249                 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP ||
 250                     p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF)))
 251                         return -EINVAL;
 252         }
 253
 254         p.i_key = p.o_key = p.i_flags = p.o_flags = 0;
 255         if (p.iph.ttl)
 256                 p.iph.frag_off |= htons(IP_DF);
 257
 258         err = ip_tunnel_ioctl(dev, &p, cmd);
 259         if (err)
 260                 return err;
 261
 262         if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p)))
 263                 return -EFAULT;
 264
 265         return 0;
 266 }
 267
 268 static const struct net_device_ops ipip_netdev_ops = {
 269         .ndo_init       = ipip_tunnel_init,
 270         .ndo_uninit     = ip_tunnel_uninit,
 271         .ndo_start_xmit = ipip_tunnel_xmit,
 272         .ndo_do_ioctl   = ipip_tunnel_ioctl,
 273         .ndo_change_mtu = ip_tunnel_change_mtu,
 274         .ndo_get_stats64 = ip_tunnel_get_stats64,
 275 };
 276
 277 #define IPIP_FEATURES (NETIF_F_SG |             \
 278                        NETIF_F_FRAGLIST |       \
 279                        NETIF_F_HIGHDMA |        \
 280                        NETIF_F_GSO_SOFTWARE |   \
 281                        NETIF_F_HW_CSUM)
 282
 283 static void ipip_tunnel_setup(struct net_device *dev)
 284 {
 285         dev->netdev_ops         = &ipip_netdev_ops;
 286
 287         dev->type               = ARPHRD_TUNNEL;
 288         dev->flags              = IFF_NOARP;
 289         dev->iflink             = 0;
 290         dev->addr_len           = 4;
 291         dev->features           |= NETIF_F_LLTX;
 292         netif_keep_dst(dev);
 293
 294         dev->features           |= IPIP_FEATURES;
 295         dev->hw_features        |= IPIP_FEATURES;
 296         ip_tunnel_setup(dev, ipip_net_id);
 297 }
 298
 299 static int ipip_tunnel_init(struct net_device *dev)
 300 {
 301         struct ip_tunnel *tunnel = netdev_priv(dev);
 302
 303         memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4);
 304         memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4);
 305
 306         tunnel->tun_hlen = 0;
 307         tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen;
 308         tunnel->parms.iph.protocol = IPPROTO_IPIP;
 309         return ip_tunnel_init(dev);
 310 }
 311
 312 static void ipip_netlink_parms(struct nlattr *data[],
 313                                struct ip_tunnel_parm *parms)
 314 {
 315         memset(parms, 0, sizeof(*parms));
 316
 317         parms->iph.version = 4;
 318         parms->iph.protocol = IPPROTO_IPIP;
 319         parms->iph.ihl = 5;
 320
 321         if (!data)
 322                 return;
 323
 324         if (data[IFLA_IPTUN_LINK])
 325                 parms->link = nla_get_u32(data[IFLA_IPTUN_LINK]);
 326
 327         if (data[IFLA_IPTUN_LOCAL])
 328                 parms->iph.saddr = nla_get_be32(data[IFLA_IPTUN_LOCAL]);
 329
 330         if (data[IFLA_IPTUN_REMOTE])
 331                 parms->iph.daddr = nla_get_be32(data[IFLA_IPTUN_REMOTE]);
 332
 333         if (data[IFLA_IPTUN_TTL]) {
 334                 parms->iph.ttl = nla_get_u8(data[IFLA_IPTUN_TTL]);
 335                 if (parms->iph.ttl)
 336                         parms->iph.frag_off = htons(IP_DF);
 337         }
 338
 339         if (data[IFLA_IPTUN_TOS])
 340                 parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]);
 341
 342         if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC]))
 343                 parms->iph.frag_off = htons(IP_DF);
 344 }
 345
 346 /* This function returns true when ENCAP attributes are present in the nl msg */
 347 static bool ipip_netlink_encap_parms(struct nlattr *data[],
 348                                      struct ip_tunnel_encap *ipencap)
 349 {
 350         bool ret = false;
 351
 352         memset(ipencap, 0, sizeof(*ipencap));
 353
 354         if (!data)
 355                 return ret;
 356
 357         if (data[IFLA_IPTUN_ENCAP_TYPE]) {
 358                 ret = true;
 359                 ipencap->type = nla_get_u16(data[IFLA_IPTUN_ENCAP_TYPE]);
 360         }
 361
 362         if (data[IFLA_IPTUN_ENCAP_FLAGS]) {
 363                 ret = true;
 364                 ipencap->flags = nla_get_u16(data[IFLA_IPTUN_ENCAP_FLAGS]);
 365         }
 366
 367         if (data[IFLA_IPTUN_ENCAP_SPORT]) {
 368                 ret = true;
 369                 ipencap->sport = nla_get_be16(data[IFLA_IPTUN_ENCAP_SPORT]);
 370         }
 371
 372         if (data[IFLA_IPTUN_ENCAP_DPORT]) {
 373                 ret = true;
 374                 ipencap->dport = nla_get_be16(data[IFLA_IPTUN_ENCAP_DPORT]);
 375         }
 376
 377         return ret;
 378 }
 379
 380 static int ipip_newlink(struct net *src_net, struct net_device *dev,
 381                         struct nlattr *tb[], struct nlattr *data[])
 382 {
 383         struct ip_tunnel_parm p;
 384         struct ip_tunnel_encap ipencap;
 385
 386         if (ipip_netlink_encap_parms(data, &ipencap)) {
 387                 struct ip_tunnel *t = netdev_priv(dev);
 388                 int err = ip_tunnel_encap_setup(t, &ipencap);
 389
 390                 if (err < 0)
 391                         return err;
 392         }
 393
 394         ipip_netlink_parms(data, &p);
 395         return ip_tunnel_newlink(dev, tb, &p);
 396 }
 397
 398 static int ipip_changelink(struct net_device *dev, struct nlattr *tb[],
 399                            struct nlattr *data[])
 400 {
 401         struct ip_tunnel_parm p;
 402         struct ip_tunnel_encap ipencap;
 403
 404         if (ipip_netlink_encap_parms(data, &ipencap)) {
 405                 struct ip_tunnel *t = netdev_priv(dev);
 406                 int err = ip_tunnel_encap_setup(t, &ipencap);
 407
 408                 if (err < 0)
 409                         return err;
 410         }
 411
 412         ipip_netlink_parms(data, &p);
 413
 414         if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) ||
 415             (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr))
 416                 return -EINVAL;
 417
 418         return ip_tunnel_changelink(dev, tb, &p);
 419 }
 420
 421 static size_t ipip_get_size(const struct net_device *dev)
 422 {
 423         return
 424                 /* IFLA_IPTUN_LINK */
 425                 nla_total_size(4) +
 426                 /* IFLA_IPTUN_LOCAL */
 427                 nla_total_size(4) +
 428                 /* IFLA_IPTUN_REMOTE */
 429                 nla_total_size(4) +
 430                 /* IFLA_IPTUN_TTL */
 431                 nla_total_size(1) +
 432                 /* IFLA_IPTUN_TOS */
 433                 nla_total_size(1) +
 434                 /* IFLA_IPTUN_PMTUDISC */
 435                 nla_total_size(1) +
 436                 /* IFLA_IPTUN_ENCAP_TYPE */
 437                 nla_total_size(2) +
 438                 /* IFLA_IPTUN_ENCAP_FLAGS */
 439                 nla_total_size(2) +
 440                 /* IFLA_IPTUN_ENCAP_SPORT */
 441                 nla_total_size(2) +
 442                 /* IFLA_IPTUN_ENCAP_DPORT */
 443                 nla_total_size(2) +
 444                 0;
 445 }
 446
 447 static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev)
 448 {
 449         struct ip_tunnel *tunnel = netdev_priv(dev);
 450         struct ip_tunnel_parm *parm = &tunnel->parms;
 451
 452         if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) ||
 453             nla_put_be32(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) ||
 454             nla_put_be32(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) ||
 455             nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) ||
 456             nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) ||
 457             nla_put_u8(skb, IFLA_IPTUN_PMTUDISC,
 458                        !!(parm->iph.frag_off & htons(IP_DF))))
 459                 goto nla_put_failure;
 460
 461         if (nla_put_u16(skb, IFLA_IPTUN_ENCAP_TYPE,
 462                         tunnel->encap.type) ||
 463             nla_put_be16(skb, IFLA_IPTUN_ENCAP_SPORT,
 464                          tunnel->encap.sport) ||
 465             nla_put_be16(skb, IFLA_IPTUN_ENCAP_DPORT,
 466                          tunnel->encap.dport) ||
 467             nla_put_u16(skb, IFLA_IPTUN_ENCAP_FLAGS,
 468                         tunnel->encap.flags))
 469                 goto nla_put_failure;
 470
 471         return 0;
 472
 473 nla_put_failure:
 474         return -EMSGSIZE;
 475 }
 476
 477 static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = {
 478         [IFLA_IPTUN_LINK]               = { .type = NLA_U32 },
 479         [IFLA_IPTUN_LOCAL]              = { .type = NLA_U32 },
 480         [IFLA_IPTUN_REMOTE]             = { .type = NLA_U32 },
 481         [IFLA_IPTUN_TTL]                = { .type = NLA_U8 },
 482         [IFLA_IPTUN_TOS]                = { .type = NLA_U8 },
 483         [IFLA_IPTUN_PMTUDISC]           = { .type = NLA_U8 },
 484         [IFLA_IPTUN_ENCAP_TYPE]         = { .type = NLA_U16 },
 485         [IFLA_IPTUN_ENCAP_FLAGS]        = { .type = NLA_U16 },
 486         [IFLA_IPTUN_ENCAP_SPORT]        = { .type = NLA_U16 },
 487         [IFLA_IPTUN_ENCAP_DPORT]        = { .type = NLA_U16 },
 488 };
 489
 490 static struct rtnl_link_ops ipip_link_ops __read_mostly = {
 491         .kind           = "ipip",
 492         .maxtype        = IFLA_IPTUN_MAX,
 493         .policy         = ipip_policy,
 494         .priv_size      = sizeof(struct ip_tunnel),
 495         .setup          = ipip_tunnel_setup,
 496         .newlink        = ipip_newlink,
 497         .changelink     = ipip_changelink,
 498         .dellink        = ip_tunnel_dellink,
 499         .get_size       = ipip_get_size,
 500         .fill_info      = ipip_fill_info,
 501         .get_link_net   = ip_tunnel_get_link_net,
 502 };
 503
 504 static struct xfrm_tunnel ipip_handler __read_mostly = {
 505         .handler        =       ipip_rcv,
 506         .err_handler    =       ipip_err,
 507         .priority       =       1,
 508 };
 509
 510 static int __net_init ipip_init_net(struct net *net)
 511 {
 512         return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0");
 513 }
 514
 515 static void __net_exit ipip_exit_net(struct net *net)
 516 {
 517         struct ip_tunnel_net *itn = net_generic(net, ipip_net_id);
 518         ip_tunnel_delete_net(itn, &ipip_link_ops);
 519 }
 520
 521 static struct pernet_operations ipip_net_ops = {
 522         .init = ipip_init_net,
 523         .exit = ipip_exit_net,
 524         .id   = &ipip_net_id,
 525         .size = sizeof(struct ip_tunnel_net),
 526 };
 527
 528 static int __init ipip_init(void)
 529 {
 530         int err;
 531
 532         pr_info("ipip: IPv4 over IPv4 tunneling driver\n");
 533
 534         err = register_pernet_device(&ipip_net_ops);
 535         if (err < 0)
 536                 return err;
 537         err = xfrm4_tunnel_register(&ipip_handler, AF_INET);
 538         if (err < 0) {
 539                 pr_info("%s: can't register tunnel\n", __func__);
 540                 goto xfrm_tunnel_failed;
 541         }
 542         err = rtnl_link_register(&ipip_link_ops);
 543         if (err < 0)
 544                 goto rtnl_link_failed;
 545
 546 out:
 547         return err;
 548
 549 rtnl_link_failed:
 550         xfrm4_tunnel_deregister(&ipip_handler, AF_INET);
 551 xfrm_tunnel_failed:
 552         unregister_pernet_device(&ipip_net_ops);
 553         goto out;
 554 }
 555
 556 static void __exit ipip_fini(void)
 557 {
 558         rtnl_link_unregister(&ipip_link_ops);
 559         if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET))
 560                 pr_info("%s: can't deregister tunnel\n", __func__);
 561
 562         unregister_pernet_device(&ipip_net_ops);
 563 }
 564
 565 module_init(ipip_init);
 566 module_exit(ipip_fini);
 567 MODULE_LICENSE("GPL");
 568 MODULE_ALIAS_RTNL_LINK("ipip");
 569 MODULE_ALIAS_NETDEV("tunl0");