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