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->dev->ifindex, 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->dev->ifindex, 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 if (iptunnel_pull_header(skb, 0, tpi.proto)) 194 goto drop; 195 196 iph = ip_hdr(skb); 197 tunnel = ip_tunnel_lookup(itn, skb->dev->ifindex, TUNNEL_NO_KEY, 198 iph->saddr, iph->daddr, 0); 199 if (tunnel) { 200 if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) 201 goto drop; 202 return ip_tunnel_rcv(tunnel, skb, &tpi, log_ecn_error); 203 } 204 205 return -1; 206 207 drop: 208 kfree_skb(skb); 209 return 0; 210 } 211 212 /* 213 * This function assumes it is being called from dev_queue_xmit() 214 * and that skb is filled properly by that function. 215 */ 216 static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev) 217 { 218 struct ip_tunnel *tunnel = netdev_priv(dev); 219 const struct iphdr *tiph = &tunnel->parms.iph; 220 221 if (unlikely(skb->protocol != htons(ETH_P_IP))) 222 goto tx_error; 223 224 if (likely(!skb->encapsulation)) { 225 skb_reset_inner_headers(skb); 226 skb->encapsulation = 1; 227 } 228 229 ip_tunnel_xmit(skb, dev, tiph, tiph->protocol); 230 return NETDEV_TX_OK; 231 232 tx_error: 233 dev->stats.tx_errors++; 234 dev_kfree_skb(skb); 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 = p.i_flags = p.o_flags = 0; 254 if (p.iph.ttl) 255 p.iph.frag_off |= htons(IP_DF); 256 257 err = ip_tunnel_ioctl(dev, &p, cmd); 258 if (err) 259 return err; 260 261 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p))) 262 return -EFAULT; 263 264 return 0; 265 } 266 267 static const struct net_device_ops ipip_netdev_ops = { 268 .ndo_init = ipip_tunnel_init, 269 .ndo_uninit = ip_tunnel_uninit, 270 .ndo_start_xmit = ipip_tunnel_xmit, 271 .ndo_do_ioctl = ipip_tunnel_ioctl, 272 .ndo_change_mtu = ip_tunnel_change_mtu, 273 .ndo_get_stats64 = ip_tunnel_get_stats64, 274 }; 275 276 #define IPIP_FEATURES (NETIF_F_SG | \ 277 NETIF_F_FRAGLIST | \ 278 NETIF_F_HIGHDMA | \ 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->iflink = 0; 288 dev->addr_len = 4; 289 dev->features |= NETIF_F_NETNS_LOCAL; 290 dev->features |= NETIF_F_LLTX; 291 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; 292 293 dev->features |= IPIP_FEATURES; 294 dev->hw_features |= IPIP_FEATURES; 295 ip_tunnel_setup(dev, ipip_net_id); 296 } 297 298 static int ipip_tunnel_init(struct net_device *dev) 299 { 300 struct ip_tunnel *tunnel = netdev_priv(dev); 301 302 memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4); 303 memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4); 304 305 tunnel->hlen = 0; 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_be32(data[IFLA_IPTUN_LOCAL]); 327 328 if (data[IFLA_IPTUN_REMOTE]) 329 parms->iph.daddr = nla_get_be32(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 static int ipip_newlink(struct net *src_net, struct net_device *dev, 345 struct nlattr *tb[], struct nlattr *data[]) 346 { 347 struct ip_tunnel_parm p; 348 349 ipip_netlink_parms(data, &p); 350 return ip_tunnel_newlink(dev, tb, &p); 351 } 352 353 static int ipip_changelink(struct net_device *dev, struct nlattr *tb[], 354 struct nlattr *data[]) 355 { 356 struct ip_tunnel_parm p; 357 358 ipip_netlink_parms(data, &p); 359 360 if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) || 361 (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr)) 362 return -EINVAL; 363 364 return ip_tunnel_changelink(dev, tb, &p); 365 } 366 367 static size_t ipip_get_size(const struct net_device *dev) 368 { 369 return 370 /* IFLA_IPTUN_LINK */ 371 nla_total_size(4) + 372 /* IFLA_IPTUN_LOCAL */ 373 nla_total_size(4) + 374 /* IFLA_IPTUN_REMOTE */ 375 nla_total_size(4) + 376 /* IFLA_IPTUN_TTL */ 377 nla_total_size(1) + 378 /* IFLA_IPTUN_TOS */ 379 nla_total_size(1) + 380 /* IFLA_IPTUN_PMTUDISC */ 381 nla_total_size(1) + 382 0; 383 } 384 385 static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev) 386 { 387 struct ip_tunnel *tunnel = netdev_priv(dev); 388 struct ip_tunnel_parm *parm = &tunnel->parms; 389 390 if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) || 391 nla_put_be32(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) || 392 nla_put_be32(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) || 393 nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) || 394 nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) || 395 nla_put_u8(skb, IFLA_IPTUN_PMTUDISC, 396 !!(parm->iph.frag_off & htons(IP_DF)))) 397 goto nla_put_failure; 398 return 0; 399 400 nla_put_failure: 401 return -EMSGSIZE; 402 } 403 404 static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = { 405 [IFLA_IPTUN_LINK] = { .type = NLA_U32 }, 406 [IFLA_IPTUN_LOCAL] = { .type = NLA_U32 }, 407 [IFLA_IPTUN_REMOTE] = { .type = NLA_U32 }, 408 [IFLA_IPTUN_TTL] = { .type = NLA_U8 }, 409 [IFLA_IPTUN_TOS] = { .type = NLA_U8 }, 410 [IFLA_IPTUN_PMTUDISC] = { .type = NLA_U8 }, 411 }; 412 413 static struct rtnl_link_ops ipip_link_ops __read_mostly = { 414 .kind = "ipip", 415 .maxtype = IFLA_IPTUN_MAX, 416 .policy = ipip_policy, 417 .priv_size = sizeof(struct ip_tunnel), 418 .setup = ipip_tunnel_setup, 419 .newlink = ipip_newlink, 420 .changelink = ipip_changelink, 421 .dellink = ip_tunnel_dellink, 422 .get_size = ipip_get_size, 423 .fill_info = ipip_fill_info, 424 }; 425 426 static struct xfrm_tunnel ipip_handler __read_mostly = { 427 .handler = ipip_rcv, 428 .err_handler = ipip_err, 429 .priority = 1, 430 }; 431 432 static int __net_init ipip_init_net(struct net *net) 433 { 434 return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0"); 435 } 436 437 static void __net_exit ipip_exit_net(struct net *net) 438 { 439 struct ip_tunnel_net *itn = net_generic(net, ipip_net_id); 440 ip_tunnel_delete_net(itn); 441 } 442 443 static struct pernet_operations ipip_net_ops = { 444 .init = ipip_init_net, 445 .exit = ipip_exit_net, 446 .id = &ipip_net_id, 447 .size = sizeof(struct ip_tunnel_net), 448 }; 449 450 static int __init ipip_init(void) 451 { 452 int err; 453 454 pr_info("ipip: IPv4 over IPv4 tunneling driver\n"); 455 456 err = register_pernet_device(&ipip_net_ops); 457 if (err < 0) 458 return err; 459 err = xfrm4_tunnel_register(&ipip_handler, AF_INET); 460 if (err < 0) { 461 pr_info("%s: can't register tunnel\n", __func__); 462 goto xfrm_tunnel_failed; 463 } 464 err = rtnl_link_register(&ipip_link_ops); 465 if (err < 0) 466 goto rtnl_link_failed; 467 468 out: 469 return err; 470 471 rtnl_link_failed: 472 xfrm4_tunnel_deregister(&ipip_handler, AF_INET); 473 xfrm_tunnel_failed: 474 unregister_pernet_device(&ipip_net_ops); 475 goto out; 476 } 477 478 static void __exit ipip_fini(void) 479 { 480 rtnl_link_unregister(&ipip_link_ops); 481 if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET)) 482 pr_info("%s: can't deregister tunnel\n", __func__); 483 484 unregister_pernet_device(&ipip_net_ops); 485 } 486 487 module_init(ipip_init); 488 module_exit(ipip_fini); 489 MODULE_LICENSE("GPL"); 490 MODULE_ALIAS_NETDEV("tunl0"); 491