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 == NULL) 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, 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 = p.i_flags = p.o_flags = 0; 255 if (p.iph.ttl) 256 p.iph.frag_off |= htons(IP_DF); 257 258 err = ip_tunnel_ioctl(dev, &p, cmd); 259 if (err) 260 return err; 261 262 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p))) 263 return -EFAULT; 264 265 return 0; 266 } 267 268 static const struct net_device_ops ipip_netdev_ops = { 269 .ndo_init = ipip_tunnel_init, 270 .ndo_uninit = ip_tunnel_uninit, 271 .ndo_start_xmit = ipip_tunnel_xmit, 272 .ndo_do_ioctl = ipip_tunnel_ioctl, 273 .ndo_change_mtu = ip_tunnel_change_mtu, 274 .ndo_get_stats64 = ip_tunnel_get_stats64, 275 }; 276 277 #define IPIP_FEATURES (NETIF_F_SG | \ 278 NETIF_F_FRAGLIST | \ 279 NETIF_F_HIGHDMA | \ 280 NETIF_F_GSO_SOFTWARE | \ 281 NETIF_F_HW_CSUM) 282 283 static void ipip_tunnel_setup(struct net_device *dev) 284 { 285 dev->netdev_ops = &ipip_netdev_ops; 286 287 dev->type = ARPHRD_TUNNEL; 288 dev->flags = IFF_NOARP; 289 dev->iflink = 0; 290 dev->addr_len = 4; 291 dev->features |= NETIF_F_LLTX; 292 netif_keep_dst(dev); 293 294 dev->features |= IPIP_FEATURES; 295 dev->hw_features |= IPIP_FEATURES; 296 ip_tunnel_setup(dev, ipip_net_id); 297 } 298 299 static int ipip_tunnel_init(struct net_device *dev) 300 { 301 struct ip_tunnel *tunnel = netdev_priv(dev); 302 303 memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4); 304 memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4); 305 306 tunnel->tun_hlen = 0; 307 tunnel->hlen = tunnel->tun_hlen + tunnel->encap_hlen; 308 tunnel->parms.iph.protocol = IPPROTO_IPIP; 309 return ip_tunnel_init(dev); 310 } 311 312 static void ipip_netlink_parms(struct nlattr *data[], 313 struct ip_tunnel_parm *parms) 314 { 315 memset(parms, 0, sizeof(*parms)); 316 317 parms->iph.version = 4; 318 parms->iph.protocol = IPPROTO_IPIP; 319 parms->iph.ihl = 5; 320 321 if (!data) 322 return; 323 324 if (data[IFLA_IPTUN_LINK]) 325 parms->link = nla_get_u32(data[IFLA_IPTUN_LINK]); 326 327 if (data[IFLA_IPTUN_LOCAL]) 328 parms->iph.saddr = nla_get_be32(data[IFLA_IPTUN_LOCAL]); 329 330 if (data[IFLA_IPTUN_REMOTE]) 331 parms->iph.daddr = nla_get_be32(data[IFLA_IPTUN_REMOTE]); 332 333 if (data[IFLA_IPTUN_TTL]) { 334 parms->iph.ttl = nla_get_u8(data[IFLA_IPTUN_TTL]); 335 if (parms->iph.ttl) 336 parms->iph.frag_off = htons(IP_DF); 337 } 338 339 if (data[IFLA_IPTUN_TOS]) 340 parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]); 341 342 if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC])) 343 parms->iph.frag_off = htons(IP_DF); 344 } 345 346 /* This function returns true when ENCAP attributes are present in the nl msg */ 347 static bool ipip_netlink_encap_parms(struct nlattr *data[], 348 struct ip_tunnel_encap *ipencap) 349 { 350 bool ret = false; 351 352 memset(ipencap, 0, sizeof(*ipencap)); 353 354 if (!data) 355 return ret; 356 357 if (data[IFLA_IPTUN_ENCAP_TYPE]) { 358 ret = true; 359 ipencap->type = nla_get_u16(data[IFLA_IPTUN_ENCAP_TYPE]); 360 } 361 362 if (data[IFLA_IPTUN_ENCAP_FLAGS]) { 363 ret = true; 364 ipencap->flags = nla_get_u16(data[IFLA_IPTUN_ENCAP_FLAGS]); 365 } 366 367 if (data[IFLA_IPTUN_ENCAP_SPORT]) { 368 ret = true; 369 ipencap->sport = nla_get_be16(data[IFLA_IPTUN_ENCAP_SPORT]); 370 } 371 372 if (data[IFLA_IPTUN_ENCAP_DPORT]) { 373 ret = true; 374 ipencap->dport = nla_get_be16(data[IFLA_IPTUN_ENCAP_DPORT]); 375 } 376 377 return ret; 378 } 379 380 static int ipip_newlink(struct net *src_net, struct net_device *dev, 381 struct nlattr *tb[], struct nlattr *data[]) 382 { 383 struct ip_tunnel_parm p; 384 struct ip_tunnel_encap ipencap; 385 386 if (ipip_netlink_encap_parms(data, &ipencap)) { 387 struct ip_tunnel *t = netdev_priv(dev); 388 int err = ip_tunnel_encap_setup(t, &ipencap); 389 390 if (err < 0) 391 return err; 392 } 393 394 ipip_netlink_parms(data, &p); 395 return ip_tunnel_newlink(dev, tb, &p); 396 } 397 398 static int ipip_changelink(struct net_device *dev, struct nlattr *tb[], 399 struct nlattr *data[]) 400 { 401 struct ip_tunnel_parm p; 402 struct ip_tunnel_encap ipencap; 403 404 if (ipip_netlink_encap_parms(data, &ipencap)) { 405 struct ip_tunnel *t = netdev_priv(dev); 406 int err = ip_tunnel_encap_setup(t, &ipencap); 407 408 if (err < 0) 409 return err; 410 } 411 412 ipip_netlink_parms(data, &p); 413 414 if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) || 415 (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr)) 416 return -EINVAL; 417 418 return ip_tunnel_changelink(dev, tb, &p); 419 } 420 421 static size_t ipip_get_size(const struct net_device *dev) 422 { 423 return 424 /* IFLA_IPTUN_LINK */ 425 nla_total_size(4) + 426 /* IFLA_IPTUN_LOCAL */ 427 nla_total_size(4) + 428 /* IFLA_IPTUN_REMOTE */ 429 nla_total_size(4) + 430 /* IFLA_IPTUN_TTL */ 431 nla_total_size(1) + 432 /* IFLA_IPTUN_TOS */ 433 nla_total_size(1) + 434 /* IFLA_IPTUN_PMTUDISC */ 435 nla_total_size(1) + 436 /* IFLA_IPTUN_ENCAP_TYPE */ 437 nla_total_size(2) + 438 /* IFLA_IPTUN_ENCAP_FLAGS */ 439 nla_total_size(2) + 440 /* IFLA_IPTUN_ENCAP_SPORT */ 441 nla_total_size(2) + 442 /* IFLA_IPTUN_ENCAP_DPORT */ 443 nla_total_size(2) + 444 0; 445 } 446 447 static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev) 448 { 449 struct ip_tunnel *tunnel = netdev_priv(dev); 450 struct ip_tunnel_parm *parm = &tunnel->parms; 451 452 if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) || 453 nla_put_be32(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) || 454 nla_put_be32(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) || 455 nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) || 456 nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) || 457 nla_put_u8(skb, IFLA_IPTUN_PMTUDISC, 458 !!(parm->iph.frag_off & htons(IP_DF)))) 459 goto nla_put_failure; 460 461 if (nla_put_u16(skb, IFLA_IPTUN_ENCAP_TYPE, 462 tunnel->encap.type) || 463 nla_put_be16(skb, IFLA_IPTUN_ENCAP_SPORT, 464 tunnel->encap.sport) || 465 nla_put_be16(skb, IFLA_IPTUN_ENCAP_DPORT, 466 tunnel->encap.dport) || 467 nla_put_u16(skb, IFLA_IPTUN_ENCAP_FLAGS, 468 tunnel->encap.flags)) 469 goto nla_put_failure; 470 471 return 0; 472 473 nla_put_failure: 474 return -EMSGSIZE; 475 } 476 477 static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = { 478 [IFLA_IPTUN_LINK] = { .type = NLA_U32 }, 479 [IFLA_IPTUN_LOCAL] = { .type = NLA_U32 }, 480 [IFLA_IPTUN_REMOTE] = { .type = NLA_U32 }, 481 [IFLA_IPTUN_TTL] = { .type = NLA_U8 }, 482 [IFLA_IPTUN_TOS] = { .type = NLA_U8 }, 483 [IFLA_IPTUN_PMTUDISC] = { .type = NLA_U8 }, 484 [IFLA_IPTUN_ENCAP_TYPE] = { .type = NLA_U16 }, 485 [IFLA_IPTUN_ENCAP_FLAGS] = { .type = NLA_U16 }, 486 [IFLA_IPTUN_ENCAP_SPORT] = { .type = NLA_U16 }, 487 [IFLA_IPTUN_ENCAP_DPORT] = { .type = NLA_U16 }, 488 }; 489 490 static struct rtnl_link_ops ipip_link_ops __read_mostly = { 491 .kind = "ipip", 492 .maxtype = IFLA_IPTUN_MAX, 493 .policy = ipip_policy, 494 .priv_size = sizeof(struct ip_tunnel), 495 .setup = ipip_tunnel_setup, 496 .newlink = ipip_newlink, 497 .changelink = ipip_changelink, 498 .dellink = ip_tunnel_dellink, 499 .get_size = ipip_get_size, 500 .fill_info = ipip_fill_info, 501 .get_link_net = ip_tunnel_get_link_net, 502 }; 503 504 static struct xfrm_tunnel ipip_handler __read_mostly = { 505 .handler = ipip_rcv, 506 .err_handler = ipip_err, 507 .priority = 1, 508 }; 509 510 static int __net_init ipip_init_net(struct net *net) 511 { 512 return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0"); 513 } 514 515 static void __net_exit ipip_exit_net(struct net *net) 516 { 517 struct ip_tunnel_net *itn = net_generic(net, ipip_net_id); 518 ip_tunnel_delete_net(itn, &ipip_link_ops); 519 } 520 521 static struct pernet_operations ipip_net_ops = { 522 .init = ipip_init_net, 523 .exit = ipip_exit_net, 524 .id = &ipip_net_id, 525 .size = sizeof(struct ip_tunnel_net), 526 }; 527 528 static int __init ipip_init(void) 529 { 530 int err; 531 532 pr_info("ipip: IPv4 over IPv4 tunneling driver\n"); 533 534 err = register_pernet_device(&ipip_net_ops); 535 if (err < 0) 536 return err; 537 err = xfrm4_tunnel_register(&ipip_handler, AF_INET); 538 if (err < 0) { 539 pr_info("%s: can't register tunnel\n", __func__); 540 goto xfrm_tunnel_failed; 541 } 542 err = rtnl_link_register(&ipip_link_ops); 543 if (err < 0) 544 goto rtnl_link_failed; 545 546 out: 547 return err; 548 549 rtnl_link_failed: 550 xfrm4_tunnel_deregister(&ipip_handler, AF_INET); 551 xfrm_tunnel_failed: 552 unregister_pernet_device(&ipip_net_ops); 553 goto out; 554 } 555 556 static void __exit ipip_fini(void) 557 { 558 rtnl_link_unregister(&ipip_link_ops); 559 if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET)) 560 pr_info("%s: can't deregister tunnel\n", __func__); 561 562 unregister_pernet_device(&ipip_net_ops); 563 } 564 565 module_init(ipip_init); 566 module_exit(ipip_fini); 567 MODULE_LICENSE("GPL"); 568 MODULE_ALIAS_RTNL_LINK("ipip"); 569 MODULE_ALIAS_NETDEV("tunl0"); 570