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/init.h> 107 #include <linux/netfilter_ipv4.h> 108 #include <linux/if_ether.h> 109 110 #include <net/sock.h> 111 #include <net/ip.h> 112 #include <net/icmp.h> 113 #include <net/ip_tunnels.h> 114 #include <net/inet_ecn.h> 115 #include <net/xfrm.h> 116 #include <net/net_namespace.h> 117 #include <net/netns/generic.h> 118 119 static bool log_ecn_error = true; 120 module_param(log_ecn_error, bool, 0644); 121 MODULE_PARM_DESC(log_ecn_error, "Log packets received with corrupted ECN"); 122 123 static int ipip_net_id __read_mostly; 124 125 static int ipip_tunnel_init(struct net_device *dev); 126 static struct rtnl_link_ops ipip_link_ops __read_mostly; 127 128 static int ipip_err(struct sk_buff *skb, u32 info) 129 { 130 131 /* All the routers (except for Linux) return only 132 8 bytes of packet payload. It means, that precise relaying of 133 ICMP in the real Internet is absolutely infeasible. 134 */ 135 struct net *net = dev_net(skb->dev); 136 struct ip_tunnel_net *itn = net_generic(net, ipip_net_id); 137 const struct iphdr *iph = (const struct iphdr *)skb->data; 138 struct ip_tunnel *t; 139 int err; 140 const int type = icmp_hdr(skb)->type; 141 const int code = icmp_hdr(skb)->code; 142 143 err = -ENOENT; 144 t = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY, 145 iph->daddr, iph->saddr, 0); 146 if (!t) 147 goto out; 148 149 if (type == ICMP_DEST_UNREACH && code == ICMP_FRAG_NEEDED) { 150 ipv4_update_pmtu(skb, dev_net(skb->dev), info, 151 t->parms.link, 0, IPPROTO_IPIP, 0); 152 err = 0; 153 goto out; 154 } 155 156 if (type == ICMP_REDIRECT) { 157 ipv4_redirect(skb, dev_net(skb->dev), t->parms.link, 0, 158 IPPROTO_IPIP, 0); 159 err = 0; 160 goto out; 161 } 162 163 if (t->parms.iph.daddr == 0) 164 goto out; 165 166 err = 0; 167 if (t->parms.iph.ttl == 0 && type == ICMP_TIME_EXCEEDED) 168 goto out; 169 170 if (time_before(jiffies, t->err_time + IPTUNNEL_ERR_TIMEO)) 171 t->err_count++; 172 else 173 t->err_count = 1; 174 t->err_time = jiffies; 175 176 out: 177 return err; 178 } 179 180 static const struct tnl_ptk_info tpi = { 181 /* no tunnel info required for ipip. */ 182 .proto = htons(ETH_P_IP), 183 }; 184 185 static int ipip_rcv(struct sk_buff *skb) 186 { 187 struct net *net = dev_net(skb->dev); 188 struct ip_tunnel_net *itn = net_generic(net, ipip_net_id); 189 struct ip_tunnel *tunnel; 190 const struct iphdr *iph; 191 192 iph = ip_hdr(skb); 193 tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY, 194 iph->saddr, iph->daddr, 0); 195 if (tunnel) { 196 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 197 goto drop; 198 if (iptunnel_pull_header(skb, 0, tpi.proto)) 199 goto drop; 200 return ip_tunnel_rcv(tunnel, skb, &tpi, NULL, log_ecn_error); 201 } 202 203 return -1; 204 205 drop: 206 kfree_skb(skb); 207 return 0; 208 } 209 210 /* 211 * This function assumes it is being called from dev_queue_xmit() 212 * and that skb is filled properly by that function. 213 */ 214 static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev) 215 { 216 struct ip_tunnel *tunnel = netdev_priv(dev); 217 const struct iphdr *tiph = &tunnel->parms.iph; 218 219 if (unlikely(skb->protocol != htons(ETH_P_IP))) 220 goto tx_error; 221 222 skb = iptunnel_handle_offloads(skb, false, SKB_GSO_IPIP); 223 if (IS_ERR(skb)) 224 goto out; 225 226 skb_set_inner_ipproto(skb, IPPROTO_IPIP); 227 228 ip_tunnel_xmit(skb, dev, tiph, tiph->protocol); 229 return NETDEV_TX_OK; 230 231 tx_error: 232 kfree_skb(skb); 233 out: 234 dev->stats.tx_errors++; 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 = 0; 254 p.i_flags = p.o_flags = 0; 255 err = ip_tunnel_ioctl(dev, &p, cmd); 256 if (err) 257 return err; 258 259 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p))) 260 return -EFAULT; 261 262 return 0; 263 } 264 265 static const struct net_device_ops ipip_netdev_ops = { 266 .ndo_init = ipip_tunnel_init, 267 .ndo_uninit = ip_tunnel_uninit, 268 .ndo_start_xmit = ipip_tunnel_xmit, 269 .ndo_do_ioctl = ipip_tunnel_ioctl, 270 .ndo_change_mtu = ip_tunnel_change_mtu, 271 .ndo_get_stats64 = ip_tunnel_get_stats64, 272 .ndo_get_iflink = ip_tunnel_get_iflink, 273 }; 274 275 #define IPIP_FEATURES (NETIF_F_SG | \ 276 NETIF_F_FRAGLIST | \ 277 NETIF_F_HIGHDMA | \ 278 NETIF_F_GSO_SOFTWARE | \ 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->addr_len = 4; 288 dev->features |= NETIF_F_LLTX; 289 netif_keep_dst(dev); 290 291 dev->features |= IPIP_FEATURES; 292 dev->hw_features |= IPIP_FEATURES; 293 ip_tunnel_setup(dev, ipip_net_id); 294 } 295 296 static int ipip_tunnel_init(struct net_device *dev) 297 { 298 struct ip_tunnel *tunnel = netdev_priv(dev); 299 300 memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4); 301 memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4); 302 303 tunnel->tun_hlen = 0; 304 tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen; 305 tunnel->parms.iph.protocol = IPPROTO_IPIP; 306 return ip_tunnel_init(dev); 307 } 308 309 static void ipip_netlink_parms(struct nlattr *data[], 310 struct ip_tunnel_parm *parms) 311 { 312 memset(parms, 0, sizeof(*parms)); 313 314 parms->iph.version = 4; 315 parms->iph.protocol = IPPROTO_IPIP; 316 parms->iph.ihl = 5; 317 318 if (!data) 319 return; 320 321 if (data[IFLA_IPTUN_LINK]) 322 parms->link = nla_get_u32(data[IFLA_IPTUN_LINK]); 323 324 if (data[IFLA_IPTUN_LOCAL]) 325 parms->iph.saddr = nla_get_in_addr(data[IFLA_IPTUN_LOCAL]); 326 327 if (data[IFLA_IPTUN_REMOTE]) 328 parms->iph.daddr = nla_get_in_addr(data[IFLA_IPTUN_REMOTE]); 329 330 if (data[IFLA_IPTUN_TTL]) { 331 parms->iph.ttl = nla_get_u8(data[IFLA_IPTUN_TTL]); 332 if (parms->iph.ttl) 333 parms->iph.frag_off = htons(IP_DF); 334 } 335 336 if (data[IFLA_IPTUN_TOS]) 337 parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]); 338 339 if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC])) 340 parms->iph.frag_off = htons(IP_DF); 341 } 342 343 /* This function returns true when ENCAP attributes are present in the nl msg */ 344 static bool ipip_netlink_encap_parms(struct nlattr *data[], 345 struct ip_tunnel_encap *ipencap) 346 { 347 bool ret = false; 348 349 memset(ipencap, 0, sizeof(*ipencap)); 350 351 if (!data) 352 return ret; 353 354 if (data[IFLA_IPTUN_ENCAP_TYPE]) { 355 ret = true; 356 ipencap->type = nla_get_u16(data[IFLA_IPTUN_ENCAP_TYPE]); 357 } 358 359 if (data[IFLA_IPTUN_ENCAP_FLAGS]) { 360 ret = true; 361 ipencap->flags = nla_get_u16(data[IFLA_IPTUN_ENCAP_FLAGS]); 362 } 363 364 if (data[IFLA_IPTUN_ENCAP_SPORT]) { 365 ret = true; 366 ipencap->sport = nla_get_be16(data[IFLA_IPTUN_ENCAP_SPORT]); 367 } 368 369 if (data[IFLA_IPTUN_ENCAP_DPORT]) { 370 ret = true; 371 ipencap->dport = nla_get_be16(data[IFLA_IPTUN_ENCAP_DPORT]); 372 } 373 374 return ret; 375 } 376 377 static int ipip_newlink(struct net *src_net, struct net_device *dev, 378 struct nlattr *tb[], struct nlattr *data[]) 379 { 380 struct ip_tunnel_parm p; 381 struct ip_tunnel_encap ipencap; 382 383 if (ipip_netlink_encap_parms(data, &ipencap)) { 384 struct ip_tunnel *t = netdev_priv(dev); 385 int err = ip_tunnel_encap_setup(t, &ipencap); 386 387 if (err < 0) 388 return err; 389 } 390 391 ipip_netlink_parms(data, &p); 392 return ip_tunnel_newlink(dev, tb, &p); 393 } 394 395 static int ipip_changelink(struct net_device *dev, struct nlattr *tb[], 396 struct nlattr *data[]) 397 { 398 struct ip_tunnel_parm p; 399 struct ip_tunnel_encap ipencap; 400 401 if (ipip_netlink_encap_parms(data, &ipencap)) { 402 struct ip_tunnel *t = netdev_priv(dev); 403 int err = ip_tunnel_encap_setup(t, &ipencap); 404 405 if (err < 0) 406 return err; 407 } 408 409 ipip_netlink_parms(data, &p); 410 411 if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) || 412 (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr)) 413 return -EINVAL; 414 415 return ip_tunnel_changelink(dev, tb, &p); 416 } 417 418 static size_t ipip_get_size(const struct net_device *dev) 419 { 420 return 421 /* IFLA_IPTUN_LINK */ 422 nla_total_size(4) + 423 /* IFLA_IPTUN_LOCAL */ 424 nla_total_size(4) + 425 /* IFLA_IPTUN_REMOTE */ 426 nla_total_size(4) + 427 /* IFLA_IPTUN_TTL */ 428 nla_total_size(1) + 429 /* IFLA_IPTUN_TOS */ 430 nla_total_size(1) + 431 /* IFLA_IPTUN_PMTUDISC */ 432 nla_total_size(1) + 433 /* IFLA_IPTUN_ENCAP_TYPE */ 434 nla_total_size(2) + 435 /* IFLA_IPTUN_ENCAP_FLAGS */ 436 nla_total_size(2) + 437 /* IFLA_IPTUN_ENCAP_SPORT */ 438 nla_total_size(2) + 439 /* IFLA_IPTUN_ENCAP_DPORT */ 440 nla_total_size(2) + 441 0; 442 } 443 444 static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev) 445 { 446 struct ip_tunnel *tunnel = netdev_priv(dev); 447 struct ip_tunnel_parm *parm = &tunnel->parms; 448 449 if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) || 450 nla_put_in_addr(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) || 451 nla_put_in_addr(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) || 452 nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) || 453 nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) || 454 nla_put_u8(skb, IFLA_IPTUN_PMTUDISC, 455 !!(parm->iph.frag_off & htons(IP_DF)))) 456 goto nla_put_failure; 457 458 if (nla_put_u16(skb, IFLA_IPTUN_ENCAP_TYPE, 459 tunnel->encap.type) || 460 nla_put_be16(skb, IFLA_IPTUN_ENCAP_SPORT, 461 tunnel->encap.sport) || 462 nla_put_be16(skb, IFLA_IPTUN_ENCAP_DPORT, 463 tunnel->encap.dport) || 464 nla_put_u16(skb, IFLA_IPTUN_ENCAP_FLAGS, 465 tunnel->encap.flags)) 466 goto nla_put_failure; 467 468 return 0; 469 470 nla_put_failure: 471 return -EMSGSIZE; 472 } 473 474 static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = { 475 [IFLA_IPTUN_LINK] = { .type = NLA_U32 }, 476 [IFLA_IPTUN_LOCAL] = { .type = NLA_U32 }, 477 [IFLA_IPTUN_REMOTE] = { .type = NLA_U32 }, 478 [IFLA_IPTUN_TTL] = { .type = NLA_U8 }, 479 [IFLA_IPTUN_TOS] = { .type = NLA_U8 }, 480 [IFLA_IPTUN_PMTUDISC] = { .type = NLA_U8 }, 481 [IFLA_IPTUN_ENCAP_TYPE] = { .type = NLA_U16 }, 482 [IFLA_IPTUN_ENCAP_FLAGS] = { .type = NLA_U16 }, 483 [IFLA_IPTUN_ENCAP_SPORT] = { .type = NLA_U16 }, 484 [IFLA_IPTUN_ENCAP_DPORT] = { .type = NLA_U16 }, 485 }; 486 487 static struct rtnl_link_ops ipip_link_ops __read_mostly = { 488 .kind = "ipip", 489 .maxtype = IFLA_IPTUN_MAX, 490 .policy = ipip_policy, 491 .priv_size = sizeof(struct ip_tunnel), 492 .setup = ipip_tunnel_setup, 493 .newlink = ipip_newlink, 494 .changelink = ipip_changelink, 495 .dellink = ip_tunnel_dellink, 496 .get_size = ipip_get_size, 497 .fill_info = ipip_fill_info, 498 .get_link_net = ip_tunnel_get_link_net, 499 }; 500 501 static struct xfrm_tunnel ipip_handler __read_mostly = { 502 .handler = ipip_rcv, 503 .err_handler = ipip_err, 504 .priority = 1, 505 }; 506 507 static int __net_init ipip_init_net(struct net *net) 508 { 509 return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0"); 510 } 511 512 static void __net_exit ipip_exit_net(struct net *net) 513 { 514 struct ip_tunnel_net *itn = net_generic(net, ipip_net_id); 515 ip_tunnel_delete_net(itn, &ipip_link_ops); 516 } 517 518 static struct pernet_operations ipip_net_ops = { 519 .init = ipip_init_net, 520 .exit = ipip_exit_net, 521 .id = &ipip_net_id, 522 .size = sizeof(struct ip_tunnel_net), 523 }; 524 525 static int __init ipip_init(void) 526 { 527 int err; 528 529 pr_info("ipip: IPv4 over IPv4 tunneling driver\n"); 530 531 err = register_pernet_device(&ipip_net_ops); 532 if (err < 0) 533 return err; 534 err = xfrm4_tunnel_register(&ipip_handler, AF_INET); 535 if (err < 0) { 536 pr_info("%s: can't register tunnel\n", __func__); 537 goto xfrm_tunnel_failed; 538 } 539 err = rtnl_link_register(&ipip_link_ops); 540 if (err < 0) 541 goto rtnl_link_failed; 542 543 out: 544 return err; 545 546 rtnl_link_failed: 547 xfrm4_tunnel_deregister(&ipip_handler, AF_INET); 548 xfrm_tunnel_failed: 549 unregister_pernet_device(&ipip_net_ops); 550 goto out; 551 } 552 553 static void __exit ipip_fini(void) 554 { 555 rtnl_link_unregister(&ipip_link_ops); 556 if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET)) 557 pr_info("%s: can't deregister tunnel\n", __func__); 558 559 unregister_pernet_device(&ipip_net_ops); 560 } 561 562 module_init(ipip_init); 563 module_exit(ipip_fini); 564 MODULE_LICENSE("GPL"); 565 MODULE_ALIAS_RTNL_LINK("ipip"); 566 MODULE_ALIAS_NETDEV("tunl0"); 567