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