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, false)) 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 if (iptunnel_handle_offloads(skb, SKB_GSO_IPXIP4)) 223 goto tx_error; 224 225 skb_set_inner_ipproto(skb, IPPROTO_IPIP); 226 227 ip_tunnel_xmit(skb, dev, tiph, tiph->protocol); 228 return NETDEV_TX_OK; 229 230 tx_error: 231 kfree_skb(skb); 232 233 dev->stats.tx_errors++; 234 return NETDEV_TX_OK; 235 } 236 237 static int 238 ipip_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) 239 { 240 int err = 0; 241 struct ip_tunnel_parm p; 242 243 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) 244 return -EFAULT; 245 246 if (cmd == SIOCADDTUNNEL || cmd == SIOCCHGTUNNEL) { 247 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP || 248 p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF))) 249 return -EINVAL; 250 } 251 252 p.i_key = p.o_key = 0; 253 p.i_flags = p.o_flags = 0; 254 err = ip_tunnel_ioctl(dev, &p, cmd); 255 if (err) 256 return err; 257 258 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p))) 259 return -EFAULT; 260 261 return 0; 262 } 263 264 static const struct net_device_ops ipip_netdev_ops = { 265 .ndo_init = ipip_tunnel_init, 266 .ndo_uninit = ip_tunnel_uninit, 267 .ndo_start_xmit = ipip_tunnel_xmit, 268 .ndo_do_ioctl = ipip_tunnel_ioctl, 269 .ndo_change_mtu = ip_tunnel_change_mtu, 270 .ndo_get_stats64 = ip_tunnel_get_stats64, 271 .ndo_get_iflink = ip_tunnel_get_iflink, 272 }; 273 274 #define IPIP_FEATURES (NETIF_F_SG | \ 275 NETIF_F_FRAGLIST | \ 276 NETIF_F_HIGHDMA | \ 277 NETIF_F_GSO_SOFTWARE | \ 278 NETIF_F_HW_CSUM) 279 280 static void ipip_tunnel_setup(struct net_device *dev) 281 { 282 dev->netdev_ops = &ipip_netdev_ops; 283 284 dev->type = ARPHRD_TUNNEL; 285 dev->flags = IFF_NOARP; 286 dev->addr_len = 4; 287 dev->features |= NETIF_F_LLTX; 288 netif_keep_dst(dev); 289 290 dev->features |= IPIP_FEATURES; 291 dev->hw_features |= IPIP_FEATURES; 292 ip_tunnel_setup(dev, ipip_net_id); 293 } 294 295 static int ipip_tunnel_init(struct net_device *dev) 296 { 297 struct ip_tunnel *tunnel = netdev_priv(dev); 298 299 memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4); 300 memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4); 301 302 tunnel->tun_hlen = 0; 303 tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen; 304 tunnel->parms.iph.protocol = IPPROTO_IPIP; 305 return ip_tunnel_init(dev); 306 } 307 308 static void ipip_netlink_parms(struct nlattr *data[], 309 struct ip_tunnel_parm *parms) 310 { 311 memset(parms, 0, sizeof(*parms)); 312 313 parms->iph.version = 4; 314 parms->iph.protocol = IPPROTO_IPIP; 315 parms->iph.ihl = 5; 316 317 if (!data) 318 return; 319 320 if (data[IFLA_IPTUN_LINK]) 321 parms->link = nla_get_u32(data[IFLA_IPTUN_LINK]); 322 323 if (data[IFLA_IPTUN_LOCAL]) 324 parms->iph.saddr = nla_get_in_addr(data[IFLA_IPTUN_LOCAL]); 325 326 if (data[IFLA_IPTUN_REMOTE]) 327 parms->iph.daddr = nla_get_in_addr(data[IFLA_IPTUN_REMOTE]); 328 329 if (data[IFLA_IPTUN_TTL]) { 330 parms->iph.ttl = nla_get_u8(data[IFLA_IPTUN_TTL]); 331 if (parms->iph.ttl) 332 parms->iph.frag_off = htons(IP_DF); 333 } 334 335 if (data[IFLA_IPTUN_TOS]) 336 parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]); 337 338 if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC])) 339 parms->iph.frag_off = htons(IP_DF); 340 } 341 342 /* This function returns true when ENCAP attributes are present in the nl msg */ 343 static bool ipip_netlink_encap_parms(struct nlattr *data[], 344 struct ip_tunnel_encap *ipencap) 345 { 346 bool ret = false; 347 348 memset(ipencap, 0, sizeof(*ipencap)); 349 350 if (!data) 351 return ret; 352 353 if (data[IFLA_IPTUN_ENCAP_TYPE]) { 354 ret = true; 355 ipencap->type = nla_get_u16(data[IFLA_IPTUN_ENCAP_TYPE]); 356 } 357 358 if (data[IFLA_IPTUN_ENCAP_FLAGS]) { 359 ret = true; 360 ipencap->flags = nla_get_u16(data[IFLA_IPTUN_ENCAP_FLAGS]); 361 } 362 363 if (data[IFLA_IPTUN_ENCAP_SPORT]) { 364 ret = true; 365 ipencap->sport = nla_get_be16(data[IFLA_IPTUN_ENCAP_SPORT]); 366 } 367 368 if (data[IFLA_IPTUN_ENCAP_DPORT]) { 369 ret = true; 370 ipencap->dport = nla_get_be16(data[IFLA_IPTUN_ENCAP_DPORT]); 371 } 372 373 return ret; 374 } 375 376 static int ipip_newlink(struct net *src_net, struct net_device *dev, 377 struct nlattr *tb[], struct nlattr *data[]) 378 { 379 struct ip_tunnel_parm p; 380 struct ip_tunnel_encap ipencap; 381 382 if (ipip_netlink_encap_parms(data, &ipencap)) { 383 struct ip_tunnel *t = netdev_priv(dev); 384 int err = ip_tunnel_encap_setup(t, &ipencap); 385 386 if (err < 0) 387 return err; 388 } 389 390 ipip_netlink_parms(data, &p); 391 return ip_tunnel_newlink(dev, tb, &p); 392 } 393 394 static int ipip_changelink(struct net_device *dev, struct nlattr *tb[], 395 struct nlattr *data[]) 396 { 397 struct ip_tunnel_parm p; 398 struct ip_tunnel_encap ipencap; 399 400 if (ipip_netlink_encap_parms(data, &ipencap)) { 401 struct ip_tunnel *t = netdev_priv(dev); 402 int err = ip_tunnel_encap_setup(t, &ipencap); 403 404 if (err < 0) 405 return err; 406 } 407 408 ipip_netlink_parms(data, &p); 409 410 if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) || 411 (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr)) 412 return -EINVAL; 413 414 return ip_tunnel_changelink(dev, tb, &p); 415 } 416 417 static size_t ipip_get_size(const struct net_device *dev) 418 { 419 return 420 /* IFLA_IPTUN_LINK */ 421 nla_total_size(4) + 422 /* IFLA_IPTUN_LOCAL */ 423 nla_total_size(4) + 424 /* IFLA_IPTUN_REMOTE */ 425 nla_total_size(4) + 426 /* IFLA_IPTUN_TTL */ 427 nla_total_size(1) + 428 /* IFLA_IPTUN_TOS */ 429 nla_total_size(1) + 430 /* IFLA_IPTUN_PMTUDISC */ 431 nla_total_size(1) + 432 /* IFLA_IPTUN_ENCAP_TYPE */ 433 nla_total_size(2) + 434 /* IFLA_IPTUN_ENCAP_FLAGS */ 435 nla_total_size(2) + 436 /* IFLA_IPTUN_ENCAP_SPORT */ 437 nla_total_size(2) + 438 /* IFLA_IPTUN_ENCAP_DPORT */ 439 nla_total_size(2) + 440 0; 441 } 442 443 static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev) 444 { 445 struct ip_tunnel *tunnel = netdev_priv(dev); 446 struct ip_tunnel_parm *parm = &tunnel->parms; 447 448 if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) || 449 nla_put_in_addr(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) || 450 nla_put_in_addr(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) || 451 nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) || 452 nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) || 453 nla_put_u8(skb, IFLA_IPTUN_PMTUDISC, 454 !!(parm->iph.frag_off & htons(IP_DF)))) 455 goto nla_put_failure; 456 457 if (nla_put_u16(skb, IFLA_IPTUN_ENCAP_TYPE, 458 tunnel->encap.type) || 459 nla_put_be16(skb, IFLA_IPTUN_ENCAP_SPORT, 460 tunnel->encap.sport) || 461 nla_put_be16(skb, IFLA_IPTUN_ENCAP_DPORT, 462 tunnel->encap.dport) || 463 nla_put_u16(skb, IFLA_IPTUN_ENCAP_FLAGS, 464 tunnel->encap.flags)) 465 goto nla_put_failure; 466 467 return 0; 468 469 nla_put_failure: 470 return -EMSGSIZE; 471 } 472 473 static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = { 474 [IFLA_IPTUN_LINK] = { .type = NLA_U32 }, 475 [IFLA_IPTUN_LOCAL] = { .type = NLA_U32 }, 476 [IFLA_IPTUN_REMOTE] = { .type = NLA_U32 }, 477 [IFLA_IPTUN_TTL] = { .type = NLA_U8 }, 478 [IFLA_IPTUN_TOS] = { .type = NLA_U8 }, 479 [IFLA_IPTUN_PMTUDISC] = { .type = NLA_U8 }, 480 [IFLA_IPTUN_ENCAP_TYPE] = { .type = NLA_U16 }, 481 [IFLA_IPTUN_ENCAP_FLAGS] = { .type = NLA_U16 }, 482 [IFLA_IPTUN_ENCAP_SPORT] = { .type = NLA_U16 }, 483 [IFLA_IPTUN_ENCAP_DPORT] = { .type = NLA_U16 }, 484 }; 485 486 static struct rtnl_link_ops ipip_link_ops __read_mostly = { 487 .kind = "ipip", 488 .maxtype = IFLA_IPTUN_MAX, 489 .policy = ipip_policy, 490 .priv_size = sizeof(struct ip_tunnel), 491 .setup = ipip_tunnel_setup, 492 .newlink = ipip_newlink, 493 .changelink = ipip_changelink, 494 .dellink = ip_tunnel_dellink, 495 .get_size = ipip_get_size, 496 .fill_info = ipip_fill_info, 497 .get_link_net = ip_tunnel_get_link_net, 498 }; 499 500 static struct xfrm_tunnel ipip_handler __read_mostly = { 501 .handler = ipip_rcv, 502 .err_handler = ipip_err, 503 .priority = 1, 504 }; 505 506 static int __net_init ipip_init_net(struct net *net) 507 { 508 return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0"); 509 } 510 511 static void __net_exit ipip_exit_net(struct net *net) 512 { 513 struct ip_tunnel_net *itn = net_generic(net, ipip_net_id); 514 ip_tunnel_delete_net(itn, &ipip_link_ops); 515 } 516 517 static struct pernet_operations ipip_net_ops = { 518 .init = ipip_init_net, 519 .exit = ipip_exit_net, 520 .id = &ipip_net_id, 521 .size = sizeof(struct ip_tunnel_net), 522 }; 523 524 static int __init ipip_init(void) 525 { 526 int err; 527 528 pr_info("ipip: IPv4 over IPv4 tunneling driver\n"); 529 530 err = register_pernet_device(&ipip_net_ops); 531 if (err < 0) 532 return err; 533 err = xfrm4_tunnel_register(&ipip_handler, AF_INET); 534 if (err < 0) { 535 pr_info("%s: can't register tunnel\n", __func__); 536 goto xfrm_tunnel_failed; 537 } 538 err = rtnl_link_register(&ipip_link_ops); 539 if (err < 0) 540 goto rtnl_link_failed; 541 542 out: 543 return err; 544 545 rtnl_link_failed: 546 xfrm4_tunnel_deregister(&ipip_handler, AF_INET); 547 xfrm_tunnel_failed: 548 unregister_pernet_device(&ipip_net_ops); 549 goto out; 550 } 551 552 static void __exit ipip_fini(void) 553 { 554 rtnl_link_unregister(&ipip_link_ops); 555 if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET)) 556 pr_info("%s: can't deregister tunnel\n", __func__); 557 558 unregister_pernet_device(&ipip_net_ops); 559 } 560 561 module_init(ipip_init); 562 module_exit(ipip_fini); 563 MODULE_LICENSE("GPL"); 564 MODULE_ALIAS_RTNL_LINK("ipip"); 565 MODULE_ALIAS_NETDEV("tunl0"); 566