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 = ip_hdr(skb); 192 193 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 return ip_tunnel_rcv(tunnel, skb, &tpi, log_ecn_error); 199 } 200 201 return -1; 202 203 drop: 204 kfree_skb(skb); 205 return 0; 206 } 207 208 /* 209 * This function assumes it is being called from dev_queue_xmit() 210 * and that skb is filled properly by that function. 211 */ 212 static netdev_tx_t ipip_tunnel_xmit(struct sk_buff *skb, struct net_device *dev) 213 { 214 struct ip_tunnel *tunnel = netdev_priv(dev); 215 const struct iphdr *tiph = &tunnel->parms.iph; 216 217 if (unlikely(skb->protocol != htons(ETH_P_IP))) 218 goto tx_error; 219 220 if (likely(!skb->encapsulation)) { 221 skb_reset_inner_headers(skb); 222 skb->encapsulation = 1; 223 } 224 225 ip_tunnel_xmit(skb, dev, tiph); 226 return NETDEV_TX_OK; 227 228 tx_error: 229 dev->stats.tx_errors++; 230 dev_kfree_skb(skb); 231 return NETDEV_TX_OK; 232 } 233 234 static int 235 ipip_tunnel_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) 236 { 237 int err = 0; 238 struct ip_tunnel_parm p; 239 240 if (copy_from_user(&p, ifr->ifr_ifru.ifru_data, sizeof(p))) 241 return -EFAULT; 242 243 if (p.iph.version != 4 || p.iph.protocol != IPPROTO_IPIP || 244 p.iph.ihl != 5 || (p.iph.frag_off&htons(~IP_DF))) 245 return -EINVAL; 246 if (p.i_key || p.o_key || p.i_flags || p.o_flags) 247 return -EINVAL; 248 if (p.iph.ttl) 249 p.iph.frag_off |= htons(IP_DF); 250 251 err = ip_tunnel_ioctl(dev, &p, cmd); 252 if (err) 253 return err; 254 255 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p))) 256 return -EFAULT; 257 258 return 0; 259 } 260 261 static const struct net_device_ops ipip_netdev_ops = { 262 .ndo_init = ipip_tunnel_init, 263 .ndo_uninit = ip_tunnel_uninit, 264 .ndo_start_xmit = ipip_tunnel_xmit, 265 .ndo_do_ioctl = ipip_tunnel_ioctl, 266 .ndo_change_mtu = ip_tunnel_change_mtu, 267 .ndo_get_stats64 = ip_tunnel_get_stats64, 268 }; 269 270 #define IPIP_FEATURES (NETIF_F_SG | \ 271 NETIF_F_FRAGLIST | \ 272 NETIF_F_HIGHDMA | \ 273 NETIF_F_HW_CSUM) 274 275 static void ipip_tunnel_setup(struct net_device *dev) 276 { 277 dev->netdev_ops = &ipip_netdev_ops; 278 279 dev->type = ARPHRD_TUNNEL; 280 dev->flags = IFF_NOARP; 281 dev->iflink = 0; 282 dev->addr_len = 4; 283 dev->features |= NETIF_F_NETNS_LOCAL; 284 dev->features |= NETIF_F_LLTX; 285 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; 286 287 dev->features |= IPIP_FEATURES; 288 dev->hw_features |= IPIP_FEATURES; 289 ip_tunnel_setup(dev, ipip_net_id); 290 } 291 292 static int ipip_tunnel_init(struct net_device *dev) 293 { 294 struct ip_tunnel *tunnel = netdev_priv(dev); 295 296 memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4); 297 memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4); 298 299 tunnel->hlen = 0; 300 tunnel->parms.iph.protocol = IPPROTO_IPIP; 301 return ip_tunnel_init(dev); 302 } 303 304 static void ipip_netlink_parms(struct nlattr *data[], 305 struct ip_tunnel_parm *parms) 306 { 307 memset(parms, 0, sizeof(*parms)); 308 309 parms->iph.version = 4; 310 parms->iph.protocol = IPPROTO_IPIP; 311 parms->iph.ihl = 5; 312 313 if (!data) 314 return; 315 316 if (data[IFLA_IPTUN_LINK]) 317 parms->link = nla_get_u32(data[IFLA_IPTUN_LINK]); 318 319 if (data[IFLA_IPTUN_LOCAL]) 320 parms->iph.saddr = nla_get_be32(data[IFLA_IPTUN_LOCAL]); 321 322 if (data[IFLA_IPTUN_REMOTE]) 323 parms->iph.daddr = nla_get_be32(data[IFLA_IPTUN_REMOTE]); 324 325 if (data[IFLA_IPTUN_TTL]) { 326 parms->iph.ttl = nla_get_u8(data[IFLA_IPTUN_TTL]); 327 if (parms->iph.ttl) 328 parms->iph.frag_off = htons(IP_DF); 329 } 330 331 if (data[IFLA_IPTUN_TOS]) 332 parms->iph.tos = nla_get_u8(data[IFLA_IPTUN_TOS]); 333 334 if (!data[IFLA_IPTUN_PMTUDISC] || nla_get_u8(data[IFLA_IPTUN_PMTUDISC])) 335 parms->iph.frag_off = htons(IP_DF); 336 } 337 338 static int ipip_newlink(struct net *src_net, struct net_device *dev, 339 struct nlattr *tb[], struct nlattr *data[]) 340 { 341 struct ip_tunnel_parm p; 342 343 ipip_netlink_parms(data, &p); 344 return ip_tunnel_newlink(dev, tb, &p); 345 } 346 347 static int ipip_changelink(struct net_device *dev, struct nlattr *tb[], 348 struct nlattr *data[]) 349 { 350 struct ip_tunnel_parm p; 351 352 ipip_netlink_parms(data, &p); 353 354 if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) || 355 (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr)) 356 return -EINVAL; 357 358 return ip_tunnel_changelink(dev, tb, &p); 359 } 360 361 static size_t ipip_get_size(const struct net_device *dev) 362 { 363 return 364 /* IFLA_IPTUN_LINK */ 365 nla_total_size(4) + 366 /* IFLA_IPTUN_LOCAL */ 367 nla_total_size(4) + 368 /* IFLA_IPTUN_REMOTE */ 369 nla_total_size(4) + 370 /* IFLA_IPTUN_TTL */ 371 nla_total_size(1) + 372 /* IFLA_IPTUN_TOS */ 373 nla_total_size(1) + 374 /* IFLA_IPTUN_PMTUDISC */ 375 nla_total_size(1) + 376 0; 377 } 378 379 static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev) 380 { 381 struct ip_tunnel *tunnel = netdev_priv(dev); 382 struct ip_tunnel_parm *parm = &tunnel->parms; 383 384 if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) || 385 nla_put_be32(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) || 386 nla_put_be32(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) || 387 nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) || 388 nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) || 389 nla_put_u8(skb, IFLA_IPTUN_PMTUDISC, 390 !!(parm->iph.frag_off & htons(IP_DF)))) 391 goto nla_put_failure; 392 return 0; 393 394 nla_put_failure: 395 return -EMSGSIZE; 396 } 397 398 static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = { 399 [IFLA_IPTUN_LINK] = { .type = NLA_U32 }, 400 [IFLA_IPTUN_LOCAL] = { .type = NLA_U32 }, 401 [IFLA_IPTUN_REMOTE] = { .type = NLA_U32 }, 402 [IFLA_IPTUN_TTL] = { .type = NLA_U8 }, 403 [IFLA_IPTUN_TOS] = { .type = NLA_U8 }, 404 [IFLA_IPTUN_PMTUDISC] = { .type = NLA_U8 }, 405 }; 406 407 static struct rtnl_link_ops ipip_link_ops __read_mostly = { 408 .kind = "ipip", 409 .maxtype = IFLA_IPTUN_MAX, 410 .policy = ipip_policy, 411 .priv_size = sizeof(struct ip_tunnel), 412 .setup = ipip_tunnel_setup, 413 .newlink = ipip_newlink, 414 .changelink = ipip_changelink, 415 .dellink = ip_tunnel_dellink, 416 .get_size = ipip_get_size, 417 .fill_info = ipip_fill_info, 418 }; 419 420 static struct xfrm_tunnel ipip_handler __read_mostly = { 421 .handler = ipip_rcv, 422 .err_handler = ipip_err, 423 .priority = 1, 424 }; 425 426 static int __net_init ipip_init_net(struct net *net) 427 { 428 return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0"); 429 } 430 431 static void __net_exit ipip_exit_net(struct net *net) 432 { 433 struct ip_tunnel_net *itn = net_generic(net, ipip_net_id); 434 ip_tunnel_delete_net(itn); 435 } 436 437 static struct pernet_operations ipip_net_ops = { 438 .init = ipip_init_net, 439 .exit = ipip_exit_net, 440 .id = &ipip_net_id, 441 .size = sizeof(struct ip_tunnel_net), 442 }; 443 444 static int __init ipip_init(void) 445 { 446 int err; 447 448 pr_info("ipip: IPv4 over IPv4 tunneling driver\n"); 449 450 err = register_pernet_device(&ipip_net_ops); 451 if (err < 0) 452 return err; 453 err = xfrm4_tunnel_register(&ipip_handler, AF_INET); 454 if (err < 0) { 455 pr_info("%s: can't register tunnel\n", __func__); 456 goto xfrm_tunnel_failed; 457 } 458 err = rtnl_link_register(&ipip_link_ops); 459 if (err < 0) 460 goto rtnl_link_failed; 461 462 out: 463 return err; 464 465 rtnl_link_failed: 466 xfrm4_tunnel_deregister(&ipip_handler, AF_INET); 467 xfrm_tunnel_failed: 468 unregister_pernet_device(&ipip_net_ops); 469 goto out; 470 } 471 472 static void __exit ipip_fini(void) 473 { 474 rtnl_link_unregister(&ipip_link_ops); 475 if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET)) 476 pr_info("%s: can't deregister tunnel\n", __func__); 477 478 unregister_pernet_device(&ipip_net_ops); 479 } 480 481 module_init(ipip_init); 482 module_exit(ipip_fini); 483 MODULE_LICENSE("GPL"); 484 MODULE_ALIAS_NETDEV("tunl0"); 485