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"); 571