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 ip_tunnel_xmit(skb, dev, tiph, tiph->protocol); 228 return NETDEV_TX_OK; 229 230 tx_error: 231 kfree_skb(skb); 232 out: 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 = p.i_flags = p.o_flags = 0; 253 if (p.iph.ttl) 254 p.iph.frag_off |= htons(IP_DF); 255 256 err = ip_tunnel_ioctl(dev, &p, cmd); 257 if (err) 258 return err; 259 260 if (copy_to_user(ifr->ifr_ifru.ifru_data, &p, sizeof(p))) 261 return -EFAULT; 262 263 return 0; 264 } 265 266 static const struct net_device_ops ipip_netdev_ops = { 267 .ndo_init = ipip_tunnel_init, 268 .ndo_uninit = ip_tunnel_uninit, 269 .ndo_start_xmit = ipip_tunnel_xmit, 270 .ndo_do_ioctl = ipip_tunnel_ioctl, 271 .ndo_change_mtu = ip_tunnel_change_mtu, 272 .ndo_get_stats64 = ip_tunnel_get_stats64, 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->iflink = 0; 288 dev->addr_len = 4; 289 dev->features |= NETIF_F_LLTX; 290 dev->priv_flags &= ~IFF_XMIT_DST_RELEASE; 291 292 dev->features |= IPIP_FEATURES; 293 dev->hw_features |= IPIP_FEATURES; 294 ip_tunnel_setup(dev, ipip_net_id); 295 } 296 297 static int ipip_tunnel_init(struct net_device *dev) 298 { 299 struct ip_tunnel *tunnel = netdev_priv(dev); 300 301 memcpy(dev->dev_addr, &tunnel->parms.iph.saddr, 4); 302 memcpy(dev->broadcast, &tunnel->parms.iph.daddr, 4); 303 304 tunnel->hlen = 0; 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_be32(data[IFLA_IPTUN_LOCAL]); 326 327 if (data[IFLA_IPTUN_REMOTE]) 328 parms->iph.daddr = nla_get_be32(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 static int ipip_newlink(struct net *src_net, struct net_device *dev, 344 struct nlattr *tb[], struct nlattr *data[]) 345 { 346 struct ip_tunnel_parm p; 347 348 ipip_netlink_parms(data, &p); 349 return ip_tunnel_newlink(dev, tb, &p); 350 } 351 352 static int ipip_changelink(struct net_device *dev, struct nlattr *tb[], 353 struct nlattr *data[]) 354 { 355 struct ip_tunnel_parm p; 356 357 ipip_netlink_parms(data, &p); 358 359 if (((dev->flags & IFF_POINTOPOINT) && !p.iph.daddr) || 360 (!(dev->flags & IFF_POINTOPOINT) && p.iph.daddr)) 361 return -EINVAL; 362 363 return ip_tunnel_changelink(dev, tb, &p); 364 } 365 366 static size_t ipip_get_size(const struct net_device *dev) 367 { 368 return 369 /* IFLA_IPTUN_LINK */ 370 nla_total_size(4) + 371 /* IFLA_IPTUN_LOCAL */ 372 nla_total_size(4) + 373 /* IFLA_IPTUN_REMOTE */ 374 nla_total_size(4) + 375 /* IFLA_IPTUN_TTL */ 376 nla_total_size(1) + 377 /* IFLA_IPTUN_TOS */ 378 nla_total_size(1) + 379 /* IFLA_IPTUN_PMTUDISC */ 380 nla_total_size(1) + 381 0; 382 } 383 384 static int ipip_fill_info(struct sk_buff *skb, const struct net_device *dev) 385 { 386 struct ip_tunnel *tunnel = netdev_priv(dev); 387 struct ip_tunnel_parm *parm = &tunnel->parms; 388 389 if (nla_put_u32(skb, IFLA_IPTUN_LINK, parm->link) || 390 nla_put_be32(skb, IFLA_IPTUN_LOCAL, parm->iph.saddr) || 391 nla_put_be32(skb, IFLA_IPTUN_REMOTE, parm->iph.daddr) || 392 nla_put_u8(skb, IFLA_IPTUN_TTL, parm->iph.ttl) || 393 nla_put_u8(skb, IFLA_IPTUN_TOS, parm->iph.tos) || 394 nla_put_u8(skb, IFLA_IPTUN_PMTUDISC, 395 !!(parm->iph.frag_off & htons(IP_DF)))) 396 goto nla_put_failure; 397 return 0; 398 399 nla_put_failure: 400 return -EMSGSIZE; 401 } 402 403 static const struct nla_policy ipip_policy[IFLA_IPTUN_MAX + 1] = { 404 [IFLA_IPTUN_LINK] = { .type = NLA_U32 }, 405 [IFLA_IPTUN_LOCAL] = { .type = NLA_U32 }, 406 [IFLA_IPTUN_REMOTE] = { .type = NLA_U32 }, 407 [IFLA_IPTUN_TTL] = { .type = NLA_U8 }, 408 [IFLA_IPTUN_TOS] = { .type = NLA_U8 }, 409 [IFLA_IPTUN_PMTUDISC] = { .type = NLA_U8 }, 410 }; 411 412 static struct rtnl_link_ops ipip_link_ops __read_mostly = { 413 .kind = "ipip", 414 .maxtype = IFLA_IPTUN_MAX, 415 .policy = ipip_policy, 416 .priv_size = sizeof(struct ip_tunnel), 417 .setup = ipip_tunnel_setup, 418 .newlink = ipip_newlink, 419 .changelink = ipip_changelink, 420 .dellink = ip_tunnel_dellink, 421 .get_size = ipip_get_size, 422 .fill_info = ipip_fill_info, 423 }; 424 425 static struct xfrm_tunnel ipip_handler __read_mostly = { 426 .handler = ipip_rcv, 427 .err_handler = ipip_err, 428 .priority = 1, 429 }; 430 431 static int __net_init ipip_init_net(struct net *net) 432 { 433 return ip_tunnel_init_net(net, ipip_net_id, &ipip_link_ops, "tunl0"); 434 } 435 436 static void __net_exit ipip_exit_net(struct net *net) 437 { 438 struct ip_tunnel_net *itn = net_generic(net, ipip_net_id); 439 ip_tunnel_delete_net(itn, &ipip_link_ops); 440 } 441 442 static struct pernet_operations ipip_net_ops = { 443 .init = ipip_init_net, 444 .exit = ipip_exit_net, 445 .id = &ipip_net_id, 446 .size = sizeof(struct ip_tunnel_net), 447 }; 448 449 static int __init ipip_init(void) 450 { 451 int err; 452 453 pr_info("ipip: IPv4 over IPv4 tunneling driver\n"); 454 455 err = register_pernet_device(&ipip_net_ops); 456 if (err < 0) 457 return err; 458 err = xfrm4_tunnel_register(&ipip_handler, AF_INET); 459 if (err < 0) { 460 pr_info("%s: can't register tunnel\n", __func__); 461 goto xfrm_tunnel_failed; 462 } 463 err = rtnl_link_register(&ipip_link_ops); 464 if (err < 0) 465 goto rtnl_link_failed; 466 467 out: 468 return err; 469 470 rtnl_link_failed: 471 xfrm4_tunnel_deregister(&ipip_handler, AF_INET); 472 xfrm_tunnel_failed: 473 unregister_pernet_device(&ipip_net_ops); 474 goto out; 475 } 476 477 static void __exit ipip_fini(void) 478 { 479 rtnl_link_unregister(&ipip_link_ops); 480 if (xfrm4_tunnel_deregister(&ipip_handler, AF_INET)) 481 pr_info("%s: can't deregister tunnel\n", __func__); 482 483 unregister_pernet_device(&ipip_net_ops); 484 } 485 486 module_init(ipip_init); 487 module_exit(ipip_fini); 488 MODULE_LICENSE("GPL"); 489 MODULE_ALIAS_RTNL_LINK("ipip"); 490 MODULE_ALIAS_NETDEV("tunl0"); 491