l2tp_core.c revision 60063497a95e716c9a689af3be2687d261f115b4
1/* 2 * L2TP core. 3 * 4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd 5 * 6 * This file contains some code of the original L2TPv2 pppol2tp 7 * driver, which has the following copyright: 8 * 9 * Authors: Martijn van Oosterhout <kleptog@svana.org> 10 * James Chapman (jchapman@katalix.com) 11 * Contributors: 12 * Michal Ostrowski <mostrows@speakeasy.net> 13 * Arnaldo Carvalho de Melo <acme@xconectiva.com.br> 14 * David S. Miller (davem@redhat.com) 15 * 16 * This program is free software; you can redistribute it and/or modify 17 * it under the terms of the GNU General Public License version 2 as 18 * published by the Free Software Foundation. 19 */ 20 21#include <linux/module.h> 22#include <linux/string.h> 23#include <linux/list.h> 24#include <linux/rculist.h> 25#include <linux/uaccess.h> 26 27#include <linux/kernel.h> 28#include <linux/spinlock.h> 29#include <linux/kthread.h> 30#include <linux/sched.h> 31#include <linux/slab.h> 32#include <linux/errno.h> 33#include <linux/jiffies.h> 34 35#include <linux/netdevice.h> 36#include <linux/net.h> 37#include <linux/inetdevice.h> 38#include <linux/skbuff.h> 39#include <linux/init.h> 40#include <linux/in.h> 41#include <linux/ip.h> 42#include <linux/udp.h> 43#include <linux/l2tp.h> 44#include <linux/hash.h> 45#include <linux/sort.h> 46#include <linux/file.h> 47#include <linux/nsproxy.h> 48#include <net/net_namespace.h> 49#include <net/netns/generic.h> 50#include <net/dst.h> 51#include <net/ip.h> 52#include <net/udp.h> 53#include <net/inet_common.h> 54#include <net/xfrm.h> 55#include <net/protocol.h> 56 57#include <asm/byteorder.h> 58#include <linux/atomic.h> 59 60#include "l2tp_core.h" 61 62#define L2TP_DRV_VERSION "V2.0" 63 64/* L2TP header constants */ 65#define L2TP_HDRFLAG_T 0x8000 66#define L2TP_HDRFLAG_L 0x4000 67#define L2TP_HDRFLAG_S 0x0800 68#define L2TP_HDRFLAG_O 0x0200 69#define L2TP_HDRFLAG_P 0x0100 70 71#define L2TP_HDR_VER_MASK 0x000F 72#define L2TP_HDR_VER_2 0x0002 73#define L2TP_HDR_VER_3 0x0003 74 75/* L2TPv3 default L2-specific sublayer */ 76#define L2TP_SLFLAG_S 0x40000000 77#define L2TP_SL_SEQ_MASK 0x00ffffff 78 79#define L2TP_HDR_SIZE_SEQ 10 80#define L2TP_HDR_SIZE_NOSEQ 6 81 82/* Default trace flags */ 83#define L2TP_DEFAULT_DEBUG_FLAGS 0 84 85#define PRINTK(_mask, _type, _lvl, _fmt, args...) \ 86 do { \ 87 if ((_mask) & (_type)) \ 88 printk(_lvl "L2TP: " _fmt, ##args); \ 89 } while (0) 90 91/* Private data stored for received packets in the skb. 92 */ 93struct l2tp_skb_cb { 94 u32 ns; 95 u16 has_seq; 96 u16 length; 97 unsigned long expires; 98}; 99 100#define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)]) 101 102static atomic_t l2tp_tunnel_count; 103static atomic_t l2tp_session_count; 104 105/* per-net private data for this module */ 106static unsigned int l2tp_net_id; 107struct l2tp_net { 108 struct list_head l2tp_tunnel_list; 109 spinlock_t l2tp_tunnel_list_lock; 110 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; 111 spinlock_t l2tp_session_hlist_lock; 112}; 113 114static void l2tp_session_set_header_len(struct l2tp_session *session, int version); 115static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel); 116static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel); 117 118static inline struct l2tp_net *l2tp_pernet(struct net *net) 119{ 120 BUG_ON(!net); 121 122 return net_generic(net, l2tp_net_id); 123} 124 125 126/* Tunnel reference counts. Incremented per session that is added to 127 * the tunnel. 128 */ 129static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel) 130{ 131 atomic_inc(&tunnel->ref_count); 132} 133 134static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel) 135{ 136 if (atomic_dec_and_test(&tunnel->ref_count)) 137 l2tp_tunnel_free(tunnel); 138} 139#ifdef L2TP_REFCNT_DEBUG 140#define l2tp_tunnel_inc_refcount(_t) do { \ 141 printk(KERN_DEBUG "l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_t)->name, atomic_read(&_t->ref_count)); \ 142 l2tp_tunnel_inc_refcount_1(_t); \ 143 } while (0) 144#define l2tp_tunnel_dec_refcount(_t) do { \ 145 printk(KERN_DEBUG "l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n", __func__, __LINE__, (_t)->name, atomic_read(&_t->ref_count)); \ 146 l2tp_tunnel_dec_refcount_1(_t); \ 147 } while (0) 148#else 149#define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t) 150#define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t) 151#endif 152 153/* Session hash global list for L2TPv3. 154 * The session_id SHOULD be random according to RFC3931, but several 155 * L2TP implementations use incrementing session_ids. So we do a real 156 * hash on the session_id, rather than a simple bitmask. 157 */ 158static inline struct hlist_head * 159l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id) 160{ 161 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)]; 162 163} 164 165/* Lookup a session by id in the global session list 166 */ 167static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id) 168{ 169 struct l2tp_net *pn = l2tp_pernet(net); 170 struct hlist_head *session_list = 171 l2tp_session_id_hash_2(pn, session_id); 172 struct l2tp_session *session; 173 struct hlist_node *walk; 174 175 rcu_read_lock_bh(); 176 hlist_for_each_entry_rcu(session, walk, session_list, global_hlist) { 177 if (session->session_id == session_id) { 178 rcu_read_unlock_bh(); 179 return session; 180 } 181 } 182 rcu_read_unlock_bh(); 183 184 return NULL; 185} 186 187/* Session hash list. 188 * The session_id SHOULD be random according to RFC2661, but several 189 * L2TP implementations (Cisco and Microsoft) use incrementing 190 * session_ids. So we do a real hash on the session_id, rather than a 191 * simple bitmask. 192 */ 193static inline struct hlist_head * 194l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id) 195{ 196 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)]; 197} 198 199/* Lookup a session by id 200 */ 201struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id) 202{ 203 struct hlist_head *session_list; 204 struct l2tp_session *session; 205 struct hlist_node *walk; 206 207 /* In L2TPv3, session_ids are unique over all tunnels and we 208 * sometimes need to look them up before we know the 209 * tunnel. 210 */ 211 if (tunnel == NULL) 212 return l2tp_session_find_2(net, session_id); 213 214 session_list = l2tp_session_id_hash(tunnel, session_id); 215 read_lock_bh(&tunnel->hlist_lock); 216 hlist_for_each_entry(session, walk, session_list, hlist) { 217 if (session->session_id == session_id) { 218 read_unlock_bh(&tunnel->hlist_lock); 219 return session; 220 } 221 } 222 read_unlock_bh(&tunnel->hlist_lock); 223 224 return NULL; 225} 226EXPORT_SYMBOL_GPL(l2tp_session_find); 227 228struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth) 229{ 230 int hash; 231 struct hlist_node *walk; 232 struct l2tp_session *session; 233 int count = 0; 234 235 read_lock_bh(&tunnel->hlist_lock); 236 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 237 hlist_for_each_entry(session, walk, &tunnel->session_hlist[hash], hlist) { 238 if (++count > nth) { 239 read_unlock_bh(&tunnel->hlist_lock); 240 return session; 241 } 242 } 243 } 244 245 read_unlock_bh(&tunnel->hlist_lock); 246 247 return NULL; 248} 249EXPORT_SYMBOL_GPL(l2tp_session_find_nth); 250 251/* Lookup a session by interface name. 252 * This is very inefficient but is only used by management interfaces. 253 */ 254struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname) 255{ 256 struct l2tp_net *pn = l2tp_pernet(net); 257 int hash; 258 struct hlist_node *walk; 259 struct l2tp_session *session; 260 261 rcu_read_lock_bh(); 262 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { 263 hlist_for_each_entry_rcu(session, walk, &pn->l2tp_session_hlist[hash], global_hlist) { 264 if (!strcmp(session->ifname, ifname)) { 265 rcu_read_unlock_bh(); 266 return session; 267 } 268 } 269 } 270 271 rcu_read_unlock_bh(); 272 273 return NULL; 274} 275EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname); 276 277/* Lookup a tunnel by id 278 */ 279struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id) 280{ 281 struct l2tp_tunnel *tunnel; 282 struct l2tp_net *pn = l2tp_pernet(net); 283 284 rcu_read_lock_bh(); 285 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 286 if (tunnel->tunnel_id == tunnel_id) { 287 rcu_read_unlock_bh(); 288 return tunnel; 289 } 290 } 291 rcu_read_unlock_bh(); 292 293 return NULL; 294} 295EXPORT_SYMBOL_GPL(l2tp_tunnel_find); 296 297struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth) 298{ 299 struct l2tp_net *pn = l2tp_pernet(net); 300 struct l2tp_tunnel *tunnel; 301 int count = 0; 302 303 rcu_read_lock_bh(); 304 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 305 if (++count > nth) { 306 rcu_read_unlock_bh(); 307 return tunnel; 308 } 309 } 310 311 rcu_read_unlock_bh(); 312 313 return NULL; 314} 315EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth); 316 317/***************************************************************************** 318 * Receive data handling 319 *****************************************************************************/ 320 321/* Queue a skb in order. We come here only if the skb has an L2TP sequence 322 * number. 323 */ 324static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb) 325{ 326 struct sk_buff *skbp; 327 struct sk_buff *tmp; 328 u32 ns = L2TP_SKB_CB(skb)->ns; 329 330 spin_lock_bh(&session->reorder_q.lock); 331 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) { 332 if (L2TP_SKB_CB(skbp)->ns > ns) { 333 __skb_queue_before(&session->reorder_q, skbp, skb); 334 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, 335 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n", 336 session->name, ns, L2TP_SKB_CB(skbp)->ns, 337 skb_queue_len(&session->reorder_q)); 338 session->stats.rx_oos_packets++; 339 goto out; 340 } 341 } 342 343 __skb_queue_tail(&session->reorder_q, skb); 344 345out: 346 spin_unlock_bh(&session->reorder_q.lock); 347} 348 349/* Dequeue a single skb. 350 */ 351static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb) 352{ 353 struct l2tp_tunnel *tunnel = session->tunnel; 354 int length = L2TP_SKB_CB(skb)->length; 355 356 /* We're about to requeue the skb, so return resources 357 * to its current owner (a socket receive buffer). 358 */ 359 skb_orphan(skb); 360 361 tunnel->stats.rx_packets++; 362 tunnel->stats.rx_bytes += length; 363 session->stats.rx_packets++; 364 session->stats.rx_bytes += length; 365 366 if (L2TP_SKB_CB(skb)->has_seq) { 367 /* Bump our Nr */ 368 session->nr++; 369 if (tunnel->version == L2TP_HDR_VER_2) 370 session->nr &= 0xffff; 371 else 372 session->nr &= 0xffffff; 373 374 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, 375 "%s: updated nr to %hu\n", session->name, session->nr); 376 } 377 378 /* call private receive handler */ 379 if (session->recv_skb != NULL) 380 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); 381 else 382 kfree_skb(skb); 383 384 if (session->deref) 385 (*session->deref)(session); 386} 387 388/* Dequeue skbs from the session's reorder_q, subject to packet order. 389 * Skbs that have been in the queue for too long are simply discarded. 390 */ 391static void l2tp_recv_dequeue(struct l2tp_session *session) 392{ 393 struct sk_buff *skb; 394 struct sk_buff *tmp; 395 396 /* If the pkt at the head of the queue has the nr that we 397 * expect to send up next, dequeue it and any other 398 * in-sequence packets behind it. 399 */ 400 spin_lock_bh(&session->reorder_q.lock); 401 skb_queue_walk_safe(&session->reorder_q, skb, tmp) { 402 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) { 403 session->stats.rx_seq_discards++; 404 session->stats.rx_errors++; 405 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, 406 "%s: oos pkt %u len %d discarded (too old), " 407 "waiting for %u, reorder_q_len=%d\n", 408 session->name, L2TP_SKB_CB(skb)->ns, 409 L2TP_SKB_CB(skb)->length, session->nr, 410 skb_queue_len(&session->reorder_q)); 411 __skb_unlink(skb, &session->reorder_q); 412 kfree_skb(skb); 413 if (session->deref) 414 (*session->deref)(session); 415 continue; 416 } 417 418 if (L2TP_SKB_CB(skb)->has_seq) { 419 if (L2TP_SKB_CB(skb)->ns != session->nr) { 420 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, 421 "%s: holding oos pkt %u len %d, " 422 "waiting for %u, reorder_q_len=%d\n", 423 session->name, L2TP_SKB_CB(skb)->ns, 424 L2TP_SKB_CB(skb)->length, session->nr, 425 skb_queue_len(&session->reorder_q)); 426 goto out; 427 } 428 } 429 __skb_unlink(skb, &session->reorder_q); 430 431 /* Process the skb. We release the queue lock while we 432 * do so to let other contexts process the queue. 433 */ 434 spin_unlock_bh(&session->reorder_q.lock); 435 l2tp_recv_dequeue_skb(session, skb); 436 spin_lock_bh(&session->reorder_q.lock); 437 } 438 439out: 440 spin_unlock_bh(&session->reorder_q.lock); 441} 442 443static inline int l2tp_verify_udp_checksum(struct sock *sk, 444 struct sk_buff *skb) 445{ 446 struct udphdr *uh = udp_hdr(skb); 447 u16 ulen = ntohs(uh->len); 448 struct inet_sock *inet; 449 __wsum psum; 450 451 if (sk->sk_no_check || skb_csum_unnecessary(skb) || !uh->check) 452 return 0; 453 454 inet = inet_sk(sk); 455 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, ulen, 456 IPPROTO_UDP, 0); 457 458 if ((skb->ip_summed == CHECKSUM_COMPLETE) && 459 !csum_fold(csum_add(psum, skb->csum))) 460 return 0; 461 462 skb->csum = psum; 463 464 return __skb_checksum_complete(skb); 465} 466 467/* Do receive processing of L2TP data frames. We handle both L2TPv2 468 * and L2TPv3 data frames here. 469 * 470 * L2TPv2 Data Message Header 471 * 472 * 0 1 2 3 473 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 474 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 475 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) | 476 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 477 * | Tunnel ID | Session ID | 478 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 479 * | Ns (opt) | Nr (opt) | 480 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 481 * | Offset Size (opt) | Offset pad... (opt) 482 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 483 * 484 * Data frames are marked by T=0. All other fields are the same as 485 * those in L2TP control frames. 486 * 487 * L2TPv3 Data Message Header 488 * 489 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 490 * | L2TP Session Header | 491 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 492 * | L2-Specific Sublayer | 493 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 494 * | Tunnel Payload ... 495 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 496 * 497 * L2TPv3 Session Header Over IP 498 * 499 * 0 1 2 3 500 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 501 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 502 * | Session ID | 503 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 504 * | Cookie (optional, maximum 64 bits)... 505 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 506 * | 507 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 508 * 509 * L2TPv3 L2-Specific Sublayer Format 510 * 511 * 0 1 2 3 512 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 513 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 514 * |x|S|x|x|x|x|x|x| Sequence Number | 515 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 516 * 517 * Cookie value, sublayer format and offset (pad) are negotiated with 518 * the peer when the session is set up. Unlike L2TPv2, we do not need 519 * to parse the packet header to determine if optional fields are 520 * present. 521 * 522 * Caller must already have parsed the frame and determined that it is 523 * a data (not control) frame before coming here. Fields up to the 524 * session-id have already been parsed and ptr points to the data 525 * after the session-id. 526 */ 527void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 528 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 529 int length, int (*payload_hook)(struct sk_buff *skb)) 530{ 531 struct l2tp_tunnel *tunnel = session->tunnel; 532 int offset; 533 u32 ns, nr; 534 535 /* The ref count is increased since we now hold a pointer to 536 * the session. Take care to decrement the refcnt when exiting 537 * this function from now on... 538 */ 539 l2tp_session_inc_refcount(session); 540 if (session->ref) 541 (*session->ref)(session); 542 543 /* Parse and check optional cookie */ 544 if (session->peer_cookie_len > 0) { 545 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { 546 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO, 547 "%s: cookie mismatch (%u/%u). Discarding.\n", 548 tunnel->name, tunnel->tunnel_id, session->session_id); 549 session->stats.rx_cookie_discards++; 550 goto discard; 551 } 552 ptr += session->peer_cookie_len; 553 } 554 555 /* Handle the optional sequence numbers. Sequence numbers are 556 * in different places for L2TPv2 and L2TPv3. 557 * 558 * If we are the LAC, enable/disable sequence numbers under 559 * the control of the LNS. If no sequence numbers present but 560 * we were expecting them, discard frame. 561 */ 562 ns = nr = 0; 563 L2TP_SKB_CB(skb)->has_seq = 0; 564 if (tunnel->version == L2TP_HDR_VER_2) { 565 if (hdrflags & L2TP_HDRFLAG_S) { 566 ns = ntohs(*(__be16 *) ptr); 567 ptr += 2; 568 nr = ntohs(*(__be16 *) ptr); 569 ptr += 2; 570 571 /* Store L2TP info in the skb */ 572 L2TP_SKB_CB(skb)->ns = ns; 573 L2TP_SKB_CB(skb)->has_seq = 1; 574 575 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, 576 "%s: recv data ns=%u, nr=%u, session nr=%u\n", 577 session->name, ns, nr, session->nr); 578 } 579 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 580 u32 l2h = ntohl(*(__be32 *) ptr); 581 582 if (l2h & 0x40000000) { 583 ns = l2h & 0x00ffffff; 584 585 /* Store L2TP info in the skb */ 586 L2TP_SKB_CB(skb)->ns = ns; 587 L2TP_SKB_CB(skb)->has_seq = 1; 588 589 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, 590 "%s: recv data ns=%u, session nr=%u\n", 591 session->name, ns, session->nr); 592 } 593 } 594 595 /* Advance past L2-specific header, if present */ 596 ptr += session->l2specific_len; 597 598 if (L2TP_SKB_CB(skb)->has_seq) { 599 /* Received a packet with sequence numbers. If we're the LNS, 600 * check if we sre sending sequence numbers and if not, 601 * configure it so. 602 */ 603 if ((!session->lns_mode) && (!session->send_seq)) { 604 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO, 605 "%s: requested to enable seq numbers by LNS\n", 606 session->name); 607 session->send_seq = -1; 608 l2tp_session_set_header_len(session, tunnel->version); 609 } 610 } else { 611 /* No sequence numbers. 612 * If user has configured mandatory sequence numbers, discard. 613 */ 614 if (session->recv_seq) { 615 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING, 616 "%s: recv data has no seq numbers when required. " 617 "Discarding\n", session->name); 618 session->stats.rx_seq_discards++; 619 goto discard; 620 } 621 622 /* If we're the LAC and we're sending sequence numbers, the 623 * LNS has requested that we no longer send sequence numbers. 624 * If we're the LNS and we're sending sequence numbers, the 625 * LAC is broken. Discard the frame. 626 */ 627 if ((!session->lns_mode) && (session->send_seq)) { 628 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_INFO, 629 "%s: requested to disable seq numbers by LNS\n", 630 session->name); 631 session->send_seq = 0; 632 l2tp_session_set_header_len(session, tunnel->version); 633 } else if (session->send_seq) { 634 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_WARNING, 635 "%s: recv data has no seq numbers when required. " 636 "Discarding\n", session->name); 637 session->stats.rx_seq_discards++; 638 goto discard; 639 } 640 } 641 642 /* Session data offset is handled differently for L2TPv2 and 643 * L2TPv3. For L2TPv2, there is an optional 16-bit value in 644 * the header. For L2TPv3, the offset is negotiated using AVPs 645 * in the session setup control protocol. 646 */ 647 if (tunnel->version == L2TP_HDR_VER_2) { 648 /* If offset bit set, skip it. */ 649 if (hdrflags & L2TP_HDRFLAG_O) { 650 offset = ntohs(*(__be16 *)ptr); 651 ptr += 2 + offset; 652 } 653 } else 654 ptr += session->offset; 655 656 offset = ptr - optr; 657 if (!pskb_may_pull(skb, offset)) 658 goto discard; 659 660 __skb_pull(skb, offset); 661 662 /* If caller wants to process the payload before we queue the 663 * packet, do so now. 664 */ 665 if (payload_hook) 666 if ((*payload_hook)(skb)) 667 goto discard; 668 669 /* Prepare skb for adding to the session's reorder_q. Hold 670 * packets for max reorder_timeout or 1 second if not 671 * reordering. 672 */ 673 L2TP_SKB_CB(skb)->length = length; 674 L2TP_SKB_CB(skb)->expires = jiffies + 675 (session->reorder_timeout ? session->reorder_timeout : HZ); 676 677 /* Add packet to the session's receive queue. Reordering is done here, if 678 * enabled. Saved L2TP protocol info is stored in skb->sb[]. 679 */ 680 if (L2TP_SKB_CB(skb)->has_seq) { 681 if (session->reorder_timeout != 0) { 682 /* Packet reordering enabled. Add skb to session's 683 * reorder queue, in order of ns. 684 */ 685 l2tp_recv_queue_skb(session, skb); 686 } else { 687 /* Packet reordering disabled. Discard out-of-sequence 688 * packets 689 */ 690 if (L2TP_SKB_CB(skb)->ns != session->nr) { 691 session->stats.rx_seq_discards++; 692 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, 693 "%s: oos pkt %u len %d discarded, " 694 "waiting for %u, reorder_q_len=%d\n", 695 session->name, L2TP_SKB_CB(skb)->ns, 696 L2TP_SKB_CB(skb)->length, session->nr, 697 skb_queue_len(&session->reorder_q)); 698 goto discard; 699 } 700 skb_queue_tail(&session->reorder_q, skb); 701 } 702 } else { 703 /* No sequence numbers. Add the skb to the tail of the 704 * reorder queue. This ensures that it will be 705 * delivered after all previous sequenced skbs. 706 */ 707 skb_queue_tail(&session->reorder_q, skb); 708 } 709 710 /* Try to dequeue as many skbs from reorder_q as we can. */ 711 l2tp_recv_dequeue(session); 712 713 l2tp_session_dec_refcount(session); 714 715 return; 716 717discard: 718 session->stats.rx_errors++; 719 kfree_skb(skb); 720 721 if (session->deref) 722 (*session->deref)(session); 723 724 l2tp_session_dec_refcount(session); 725} 726EXPORT_SYMBOL(l2tp_recv_common); 727 728/* Internal UDP receive frame. Do the real work of receiving an L2TP data frame 729 * here. The skb is not on a list when we get here. 730 * Returns 0 if the packet was a data packet and was successfully passed on. 731 * Returns 1 if the packet was not a good data packet and could not be 732 * forwarded. All such packets are passed up to userspace to deal with. 733 */ 734static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, 735 int (*payload_hook)(struct sk_buff *skb)) 736{ 737 struct l2tp_session *session = NULL; 738 unsigned char *ptr, *optr; 739 u16 hdrflags; 740 u32 tunnel_id, session_id; 741 int offset; 742 u16 version; 743 int length; 744 745 if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb)) 746 goto discard_bad_csum; 747 748 /* UDP always verifies the packet length. */ 749 __skb_pull(skb, sizeof(struct udphdr)); 750 751 /* Short packet? */ 752 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) { 753 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO, 754 "%s: recv short packet (len=%d)\n", tunnel->name, skb->len); 755 goto error; 756 } 757 758 /* Point to L2TP header */ 759 optr = ptr = skb->data; 760 761 /* Trace packet contents, if enabled */ 762 if (tunnel->debug & L2TP_MSG_DATA) { 763 length = min(32u, skb->len); 764 if (!pskb_may_pull(skb, length)) 765 goto error; 766 767 printk(KERN_DEBUG "%s: recv: ", tunnel->name); 768 769 offset = 0; 770 do { 771 printk(" %02X", ptr[offset]); 772 } while (++offset < length); 773 774 printk("\n"); 775 } 776 777 /* Get L2TP header flags */ 778 hdrflags = ntohs(*(__be16 *) ptr); 779 780 /* Check protocol version */ 781 version = hdrflags & L2TP_HDR_VER_MASK; 782 if (version != tunnel->version) { 783 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO, 784 "%s: recv protocol version mismatch: got %d expected %d\n", 785 tunnel->name, version, tunnel->version); 786 goto error; 787 } 788 789 /* Get length of L2TP packet */ 790 length = skb->len; 791 792 /* If type is control packet, it is handled by userspace. */ 793 if (hdrflags & L2TP_HDRFLAG_T) { 794 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG, 795 "%s: recv control packet, len=%d\n", tunnel->name, length); 796 goto error; 797 } 798 799 /* Skip flags */ 800 ptr += 2; 801 802 if (tunnel->version == L2TP_HDR_VER_2) { 803 /* If length is present, skip it */ 804 if (hdrflags & L2TP_HDRFLAG_L) 805 ptr += 2; 806 807 /* Extract tunnel and session ID */ 808 tunnel_id = ntohs(*(__be16 *) ptr); 809 ptr += 2; 810 session_id = ntohs(*(__be16 *) ptr); 811 ptr += 2; 812 } else { 813 ptr += 2; /* skip reserved bits */ 814 tunnel_id = tunnel->tunnel_id; 815 session_id = ntohl(*(__be32 *) ptr); 816 ptr += 4; 817 } 818 819 /* Find the session context */ 820 session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id); 821 if (!session || !session->recv_skb) { 822 /* Not found? Pass to userspace to deal with */ 823 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_INFO, 824 "%s: no session found (%u/%u). Passing up.\n", 825 tunnel->name, tunnel_id, session_id); 826 goto error; 827 } 828 829 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook); 830 831 return 0; 832 833discard_bad_csum: 834 LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name); 835 UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0); 836 tunnel->stats.rx_errors++; 837 kfree_skb(skb); 838 839 return 0; 840 841error: 842 /* Put UDP header back */ 843 __skb_push(skb, sizeof(struct udphdr)); 844 845 return 1; 846} 847 848/* UDP encapsulation receive handler. See net/ipv4/udp.c. 849 * Return codes: 850 * 0 : success. 851 * <0: error 852 * >0: skb should be passed up to userspace as UDP. 853 */ 854int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 855{ 856 struct l2tp_tunnel *tunnel; 857 858 tunnel = l2tp_sock_to_tunnel(sk); 859 if (tunnel == NULL) 860 goto pass_up; 861 862 PRINTK(tunnel->debug, L2TP_MSG_DATA, KERN_DEBUG, 863 "%s: received %d bytes\n", tunnel->name, skb->len); 864 865 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook)) 866 goto pass_up_put; 867 868 sock_put(sk); 869 return 0; 870 871pass_up_put: 872 sock_put(sk); 873pass_up: 874 return 1; 875} 876EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 877 878/************************************************************************ 879 * Transmit handling 880 ***********************************************************************/ 881 882/* Build an L2TP header for the session into the buffer provided. 883 */ 884static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 885{ 886 struct l2tp_tunnel *tunnel = session->tunnel; 887 __be16 *bufp = buf; 888 __be16 *optr = buf; 889 u16 flags = L2TP_HDR_VER_2; 890 u32 tunnel_id = tunnel->peer_tunnel_id; 891 u32 session_id = session->peer_session_id; 892 893 if (session->send_seq) 894 flags |= L2TP_HDRFLAG_S; 895 896 /* Setup L2TP header. */ 897 *bufp++ = htons(flags); 898 *bufp++ = htons(tunnel_id); 899 *bufp++ = htons(session_id); 900 if (session->send_seq) { 901 *bufp++ = htons(session->ns); 902 *bufp++ = 0; 903 session->ns++; 904 session->ns &= 0xffff; 905 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, 906 "%s: updated ns to %u\n", session->name, session->ns); 907 } 908 909 return bufp - optr; 910} 911 912static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 913{ 914 struct l2tp_tunnel *tunnel = session->tunnel; 915 char *bufp = buf; 916 char *optr = bufp; 917 918 /* Setup L2TP header. The header differs slightly for UDP and 919 * IP encapsulations. For UDP, there is 4 bytes of flags. 920 */ 921 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 922 u16 flags = L2TP_HDR_VER_3; 923 *((__be16 *) bufp) = htons(flags); 924 bufp += 2; 925 *((__be16 *) bufp) = 0; 926 bufp += 2; 927 } 928 929 *((__be32 *) bufp) = htonl(session->peer_session_id); 930 bufp += 4; 931 if (session->cookie_len) { 932 memcpy(bufp, &session->cookie[0], session->cookie_len); 933 bufp += session->cookie_len; 934 } 935 if (session->l2specific_len) { 936 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 937 u32 l2h = 0; 938 if (session->send_seq) { 939 l2h = 0x40000000 | session->ns; 940 session->ns++; 941 session->ns &= 0xffffff; 942 PRINTK(session->debug, L2TP_MSG_SEQ, KERN_DEBUG, 943 "%s: updated ns to %u\n", session->name, session->ns); 944 } 945 946 *((__be32 *) bufp) = htonl(l2h); 947 } 948 bufp += session->l2specific_len; 949 } 950 if (session->offset) 951 bufp += session->offset; 952 953 return bufp - optr; 954} 955 956static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, 957 struct flowi *fl, size_t data_len) 958{ 959 struct l2tp_tunnel *tunnel = session->tunnel; 960 unsigned int len = skb->len; 961 int error; 962 963 /* Debug */ 964 if (session->send_seq) 965 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG, 966 "%s: send %Zd bytes, ns=%u\n", session->name, 967 data_len, session->ns - 1); 968 else 969 PRINTK(session->debug, L2TP_MSG_DATA, KERN_DEBUG, 970 "%s: send %Zd bytes\n", session->name, data_len); 971 972 if (session->debug & L2TP_MSG_DATA) { 973 int i; 974 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 975 unsigned char *datap = skb->data + uhlen; 976 977 printk(KERN_DEBUG "%s: xmit:", session->name); 978 for (i = 0; i < (len - uhlen); i++) { 979 printk(" %02X", *datap++); 980 if (i == 31) { 981 printk(" ..."); 982 break; 983 } 984 } 985 printk("\n"); 986 } 987 988 /* Queue the packet to IP for output */ 989 skb->local_df = 1; 990 error = ip_queue_xmit(skb, fl); 991 992 /* Update stats */ 993 if (error >= 0) { 994 tunnel->stats.tx_packets++; 995 tunnel->stats.tx_bytes += len; 996 session->stats.tx_packets++; 997 session->stats.tx_bytes += len; 998 } else { 999 tunnel->stats.tx_errors++; 1000 session->stats.tx_errors++; 1001 } 1002 1003 return 0; 1004} 1005 1006/* Automatically called when the skb is freed. 1007 */ 1008static void l2tp_sock_wfree(struct sk_buff *skb) 1009{ 1010 sock_put(skb->sk); 1011} 1012 1013/* For data skbs that we transmit, we associate with the tunnel socket 1014 * but don't do accounting. 1015 */ 1016static inline void l2tp_skb_set_owner_w(struct sk_buff *skb, struct sock *sk) 1017{ 1018 sock_hold(sk); 1019 skb->sk = sk; 1020 skb->destructor = l2tp_sock_wfree; 1021} 1022 1023/* If caller requires the skb to have a ppp header, the header must be 1024 * inserted in the skb data before calling this function. 1025 */ 1026int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len) 1027{ 1028 int data_len = skb->len; 1029 struct l2tp_tunnel *tunnel = session->tunnel; 1030 struct sock *sk = tunnel->sock; 1031 struct flowi *fl; 1032 struct udphdr *uh; 1033 struct inet_sock *inet; 1034 __wsum csum; 1035 int old_headroom; 1036 int new_headroom; 1037 int headroom; 1038 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1039 int udp_len; 1040 1041 /* Check that there's enough headroom in the skb to insert IP, 1042 * UDP and L2TP headers. If not enough, expand it to 1043 * make room. Adjust truesize. 1044 */ 1045 headroom = NET_SKB_PAD + sizeof(struct iphdr) + 1046 uhlen + hdr_len; 1047 old_headroom = skb_headroom(skb); 1048 if (skb_cow_head(skb, headroom)) 1049 goto abort; 1050 1051 new_headroom = skb_headroom(skb); 1052 skb_orphan(skb); 1053 skb->truesize += new_headroom - old_headroom; 1054 1055 /* Setup L2TP header */ 1056 session->build_header(session, __skb_push(skb, hdr_len)); 1057 1058 /* Reset skb netfilter state */ 1059 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1060 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | 1061 IPSKB_REROUTED); 1062 nf_reset(skb); 1063 1064 bh_lock_sock(sk); 1065 if (sock_owned_by_user(sk)) { 1066 dev_kfree_skb(skb); 1067 goto out_unlock; 1068 } 1069 1070 /* Get routing info from the tunnel socket */ 1071 skb_dst_drop(skb); 1072 skb_dst_set(skb, dst_clone(__sk_dst_get(sk))); 1073 1074 inet = inet_sk(sk); 1075 fl = &inet->cork.fl; 1076 switch (tunnel->encap) { 1077 case L2TP_ENCAPTYPE_UDP: 1078 /* Setup UDP header */ 1079 __skb_push(skb, sizeof(*uh)); 1080 skb_reset_transport_header(skb); 1081 uh = udp_hdr(skb); 1082 uh->source = inet->inet_sport; 1083 uh->dest = inet->inet_dport; 1084 udp_len = uhlen + hdr_len + data_len; 1085 uh->len = htons(udp_len); 1086 uh->check = 0; 1087 1088 /* Calculate UDP checksum if configured to do so */ 1089 if (sk->sk_no_check == UDP_CSUM_NOXMIT) 1090 skb->ip_summed = CHECKSUM_NONE; 1091 else if ((skb_dst(skb) && skb_dst(skb)->dev) && 1092 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) { 1093 skb->ip_summed = CHECKSUM_COMPLETE; 1094 csum = skb_checksum(skb, 0, udp_len, 0); 1095 uh->check = csum_tcpudp_magic(inet->inet_saddr, 1096 inet->inet_daddr, 1097 udp_len, IPPROTO_UDP, csum); 1098 if (uh->check == 0) 1099 uh->check = CSUM_MANGLED_0; 1100 } else { 1101 skb->ip_summed = CHECKSUM_PARTIAL; 1102 skb->csum_start = skb_transport_header(skb) - skb->head; 1103 skb->csum_offset = offsetof(struct udphdr, check); 1104 uh->check = ~csum_tcpudp_magic(inet->inet_saddr, 1105 inet->inet_daddr, 1106 udp_len, IPPROTO_UDP, 0); 1107 } 1108 break; 1109 1110 case L2TP_ENCAPTYPE_IP: 1111 break; 1112 } 1113 1114 l2tp_skb_set_owner_w(skb, sk); 1115 1116 l2tp_xmit_core(session, skb, fl, data_len); 1117out_unlock: 1118 bh_unlock_sock(sk); 1119 1120abort: 1121 return 0; 1122} 1123EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1124 1125/***************************************************************************** 1126 * Tinnel and session create/destroy. 1127 *****************************************************************************/ 1128 1129/* Tunnel socket destruct hook. 1130 * The tunnel context is deleted only when all session sockets have been 1131 * closed. 1132 */ 1133static void l2tp_tunnel_destruct(struct sock *sk) 1134{ 1135 struct l2tp_tunnel *tunnel; 1136 1137 tunnel = sk->sk_user_data; 1138 if (tunnel == NULL) 1139 goto end; 1140 1141 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO, 1142 "%s: closing...\n", tunnel->name); 1143 1144 /* Close all sessions */ 1145 l2tp_tunnel_closeall(tunnel); 1146 1147 switch (tunnel->encap) { 1148 case L2TP_ENCAPTYPE_UDP: 1149 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1150 (udp_sk(sk))->encap_type = 0; 1151 (udp_sk(sk))->encap_rcv = NULL; 1152 break; 1153 case L2TP_ENCAPTYPE_IP: 1154 break; 1155 } 1156 1157 /* Remove hooks into tunnel socket */ 1158 tunnel->sock = NULL; 1159 sk->sk_destruct = tunnel->old_sk_destruct; 1160 sk->sk_user_data = NULL; 1161 1162 /* Call the original destructor */ 1163 if (sk->sk_destruct) 1164 (*sk->sk_destruct)(sk); 1165 1166 /* We're finished with the socket */ 1167 l2tp_tunnel_dec_refcount(tunnel); 1168 1169end: 1170 return; 1171} 1172 1173/* When the tunnel is closed, all the attached sessions need to go too. 1174 */ 1175static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1176{ 1177 int hash; 1178 struct hlist_node *walk; 1179 struct hlist_node *tmp; 1180 struct l2tp_session *session; 1181 1182 BUG_ON(tunnel == NULL); 1183 1184 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO, 1185 "%s: closing all sessions...\n", tunnel->name); 1186 1187 write_lock_bh(&tunnel->hlist_lock); 1188 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1189again: 1190 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) { 1191 session = hlist_entry(walk, struct l2tp_session, hlist); 1192 1193 PRINTK(session->debug, L2TP_MSG_CONTROL, KERN_INFO, 1194 "%s: closing session\n", session->name); 1195 1196 hlist_del_init(&session->hlist); 1197 1198 /* Since we should hold the sock lock while 1199 * doing any unbinding, we need to release the 1200 * lock we're holding before taking that lock. 1201 * Hold a reference to the sock so it doesn't 1202 * disappear as we're jumping between locks. 1203 */ 1204 if (session->ref != NULL) 1205 (*session->ref)(session); 1206 1207 write_unlock_bh(&tunnel->hlist_lock); 1208 1209 if (tunnel->version != L2TP_HDR_VER_2) { 1210 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1211 1212 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1213 hlist_del_init_rcu(&session->global_hlist); 1214 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1215 synchronize_rcu(); 1216 } 1217 1218 if (session->session_close != NULL) 1219 (*session->session_close)(session); 1220 1221 if (session->deref != NULL) 1222 (*session->deref)(session); 1223 1224 write_lock_bh(&tunnel->hlist_lock); 1225 1226 /* Now restart from the beginning of this hash 1227 * chain. We always remove a session from the 1228 * list so we are guaranteed to make forward 1229 * progress. 1230 */ 1231 goto again; 1232 } 1233 } 1234 write_unlock_bh(&tunnel->hlist_lock); 1235} 1236 1237/* Really kill the tunnel. 1238 * Come here only when all sessions have been cleared from the tunnel. 1239 */ 1240static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) 1241{ 1242 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1243 1244 BUG_ON(atomic_read(&tunnel->ref_count) != 0); 1245 BUG_ON(tunnel->sock != NULL); 1246 1247 PRINTK(tunnel->debug, L2TP_MSG_CONTROL, KERN_INFO, 1248 "%s: free...\n", tunnel->name); 1249 1250 /* Remove from tunnel list */ 1251 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1252 list_del_rcu(&tunnel->list); 1253 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1254 synchronize_rcu(); 1255 1256 atomic_dec(&l2tp_tunnel_count); 1257 kfree(tunnel); 1258} 1259 1260/* Create a socket for the tunnel, if one isn't set up by 1261 * userspace. This is used for static tunnels where there is no 1262 * managing L2TP daemon. 1263 */ 1264static int l2tp_tunnel_sock_create(u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct socket **sockp) 1265{ 1266 int err = -EINVAL; 1267 struct sockaddr_in udp_addr; 1268 struct sockaddr_l2tpip ip_addr; 1269 struct socket *sock = NULL; 1270 1271 switch (cfg->encap) { 1272 case L2TP_ENCAPTYPE_UDP: 1273 err = sock_create(AF_INET, SOCK_DGRAM, 0, sockp); 1274 if (err < 0) 1275 goto out; 1276 1277 sock = *sockp; 1278 1279 memset(&udp_addr, 0, sizeof(udp_addr)); 1280 udp_addr.sin_family = AF_INET; 1281 udp_addr.sin_addr = cfg->local_ip; 1282 udp_addr.sin_port = htons(cfg->local_udp_port); 1283 err = kernel_bind(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr)); 1284 if (err < 0) 1285 goto out; 1286 1287 udp_addr.sin_family = AF_INET; 1288 udp_addr.sin_addr = cfg->peer_ip; 1289 udp_addr.sin_port = htons(cfg->peer_udp_port); 1290 err = kernel_connect(sock, (struct sockaddr *) &udp_addr, sizeof(udp_addr), 0); 1291 if (err < 0) 1292 goto out; 1293 1294 if (!cfg->use_udp_checksums) 1295 sock->sk->sk_no_check = UDP_CSUM_NOXMIT; 1296 1297 break; 1298 1299 case L2TP_ENCAPTYPE_IP: 1300 err = sock_create(AF_INET, SOCK_DGRAM, IPPROTO_L2TP, sockp); 1301 if (err < 0) 1302 goto out; 1303 1304 sock = *sockp; 1305 1306 memset(&ip_addr, 0, sizeof(ip_addr)); 1307 ip_addr.l2tp_family = AF_INET; 1308 ip_addr.l2tp_addr = cfg->local_ip; 1309 ip_addr.l2tp_conn_id = tunnel_id; 1310 err = kernel_bind(sock, (struct sockaddr *) &ip_addr, sizeof(ip_addr)); 1311 if (err < 0) 1312 goto out; 1313 1314 ip_addr.l2tp_family = AF_INET; 1315 ip_addr.l2tp_addr = cfg->peer_ip; 1316 ip_addr.l2tp_conn_id = peer_tunnel_id; 1317 err = kernel_connect(sock, (struct sockaddr *) &ip_addr, sizeof(ip_addr), 0); 1318 if (err < 0) 1319 goto out; 1320 1321 break; 1322 1323 default: 1324 goto out; 1325 } 1326 1327out: 1328 if ((err < 0) && sock) { 1329 sock_release(sock); 1330 *sockp = NULL; 1331 } 1332 1333 return err; 1334} 1335 1336int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp) 1337{ 1338 struct l2tp_tunnel *tunnel = NULL; 1339 int err; 1340 struct socket *sock = NULL; 1341 struct sock *sk = NULL; 1342 struct l2tp_net *pn; 1343 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1344 1345 /* Get the tunnel socket from the fd, which was opened by 1346 * the userspace L2TP daemon. If not specified, create a 1347 * kernel socket. 1348 */ 1349 if (fd < 0) { 1350 err = l2tp_tunnel_sock_create(tunnel_id, peer_tunnel_id, cfg, &sock); 1351 if (err < 0) 1352 goto err; 1353 } else { 1354 err = -EBADF; 1355 sock = sockfd_lookup(fd, &err); 1356 if (!sock) { 1357 printk(KERN_ERR "tunl %hu: sockfd_lookup(fd=%d) returned %d\n", 1358 tunnel_id, fd, err); 1359 goto err; 1360 } 1361 } 1362 1363 sk = sock->sk; 1364 1365 if (cfg != NULL) 1366 encap = cfg->encap; 1367 1368 /* Quick sanity checks */ 1369 switch (encap) { 1370 case L2TP_ENCAPTYPE_UDP: 1371 err = -EPROTONOSUPPORT; 1372 if (sk->sk_protocol != IPPROTO_UDP) { 1373 printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n", 1374 tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP); 1375 goto err; 1376 } 1377 break; 1378 case L2TP_ENCAPTYPE_IP: 1379 err = -EPROTONOSUPPORT; 1380 if (sk->sk_protocol != IPPROTO_L2TP) { 1381 printk(KERN_ERR "tunl %hu: fd %d wrong protocol, got %d, expected %d\n", 1382 tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP); 1383 goto err; 1384 } 1385 break; 1386 } 1387 1388 /* Check if this socket has already been prepped */ 1389 tunnel = (struct l2tp_tunnel *)sk->sk_user_data; 1390 if (tunnel != NULL) { 1391 /* This socket has already been prepped */ 1392 err = -EBUSY; 1393 goto err; 1394 } 1395 1396 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL); 1397 if (tunnel == NULL) { 1398 err = -ENOMEM; 1399 goto err; 1400 } 1401 1402 tunnel->version = version; 1403 tunnel->tunnel_id = tunnel_id; 1404 tunnel->peer_tunnel_id = peer_tunnel_id; 1405 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS; 1406 1407 tunnel->magic = L2TP_TUNNEL_MAGIC; 1408 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1409 rwlock_init(&tunnel->hlist_lock); 1410 1411 /* The net we belong to */ 1412 tunnel->l2tp_net = net; 1413 pn = l2tp_pernet(net); 1414 1415 if (cfg != NULL) 1416 tunnel->debug = cfg->debug; 1417 1418 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */ 1419 tunnel->encap = encap; 1420 if (encap == L2TP_ENCAPTYPE_UDP) { 1421 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */ 1422 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP; 1423 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv; 1424 } 1425 1426 sk->sk_user_data = tunnel; 1427 1428 /* Hook on the tunnel socket destructor so that we can cleanup 1429 * if the tunnel socket goes away. 1430 */ 1431 tunnel->old_sk_destruct = sk->sk_destruct; 1432 sk->sk_destruct = &l2tp_tunnel_destruct; 1433 tunnel->sock = sk; 1434 sk->sk_allocation = GFP_ATOMIC; 1435 1436 /* Add tunnel to our list */ 1437 INIT_LIST_HEAD(&tunnel->list); 1438 atomic_inc(&l2tp_tunnel_count); 1439 1440 /* Bump the reference count. The tunnel context is deleted 1441 * only when this drops to zero. Must be done before list insertion 1442 */ 1443 l2tp_tunnel_inc_refcount(tunnel); 1444 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1445 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); 1446 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1447 1448 err = 0; 1449err: 1450 if (tunnelp) 1451 *tunnelp = tunnel; 1452 1453 /* If tunnel's socket was created by the kernel, it doesn't 1454 * have a file. 1455 */ 1456 if (sock && sock->file) 1457 sockfd_put(sock); 1458 1459 return err; 1460} 1461EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1462 1463/* This function is used by the netlink TUNNEL_DELETE command. 1464 */ 1465int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1466{ 1467 int err = 0; 1468 struct socket *sock = tunnel->sock ? tunnel->sock->sk_socket : NULL; 1469 1470 /* Force the tunnel socket to close. This will eventually 1471 * cause the tunnel to be deleted via the normal socket close 1472 * mechanisms when userspace closes the tunnel socket. 1473 */ 1474 if (sock != NULL) { 1475 err = inet_shutdown(sock, 2); 1476 1477 /* If the tunnel's socket was created by the kernel, 1478 * close the socket here since the socket was not 1479 * created by userspace. 1480 */ 1481 if (sock->file == NULL) 1482 err = inet_release(sock); 1483 } 1484 1485 return err; 1486} 1487EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1488 1489/* Really kill the session. 1490 */ 1491void l2tp_session_free(struct l2tp_session *session) 1492{ 1493 struct l2tp_tunnel *tunnel; 1494 1495 BUG_ON(atomic_read(&session->ref_count) != 0); 1496 1497 tunnel = session->tunnel; 1498 if (tunnel != NULL) { 1499 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC); 1500 1501 /* Delete the session from the hash */ 1502 write_lock_bh(&tunnel->hlist_lock); 1503 hlist_del_init(&session->hlist); 1504 write_unlock_bh(&tunnel->hlist_lock); 1505 1506 /* Unlink from the global hash if not L2TPv2 */ 1507 if (tunnel->version != L2TP_HDR_VER_2) { 1508 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1509 1510 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1511 hlist_del_init_rcu(&session->global_hlist); 1512 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1513 synchronize_rcu(); 1514 } 1515 1516 if (session->session_id != 0) 1517 atomic_dec(&l2tp_session_count); 1518 1519 sock_put(tunnel->sock); 1520 1521 /* This will delete the tunnel context if this 1522 * is the last session on the tunnel. 1523 */ 1524 session->tunnel = NULL; 1525 l2tp_tunnel_dec_refcount(tunnel); 1526 } 1527 1528 kfree(session); 1529 1530 return; 1531} 1532EXPORT_SYMBOL_GPL(l2tp_session_free); 1533 1534/* This function is used by the netlink SESSION_DELETE command and by 1535 pseudowire modules. 1536 */ 1537int l2tp_session_delete(struct l2tp_session *session) 1538{ 1539 if (session->session_close != NULL) 1540 (*session->session_close)(session); 1541 1542 l2tp_session_dec_refcount(session); 1543 1544 return 0; 1545} 1546EXPORT_SYMBOL_GPL(l2tp_session_delete); 1547 1548 1549/* We come here whenever a session's send_seq, cookie_len or 1550 * l2specific_len parameters are set. 1551 */ 1552static void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1553{ 1554 if (version == L2TP_HDR_VER_2) { 1555 session->hdr_len = 6; 1556 if (session->send_seq) 1557 session->hdr_len += 4; 1558 } else { 1559 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset; 1560 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1561 session->hdr_len += 4; 1562 } 1563 1564} 1565 1566struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg) 1567{ 1568 struct l2tp_session *session; 1569 1570 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL); 1571 if (session != NULL) { 1572 session->magic = L2TP_SESSION_MAGIC; 1573 session->tunnel = tunnel; 1574 1575 session->session_id = session_id; 1576 session->peer_session_id = peer_session_id; 1577 session->nr = 1; 1578 1579 sprintf(&session->name[0], "sess %u/%u", 1580 tunnel->tunnel_id, session->session_id); 1581 1582 skb_queue_head_init(&session->reorder_q); 1583 1584 INIT_HLIST_NODE(&session->hlist); 1585 INIT_HLIST_NODE(&session->global_hlist); 1586 1587 /* Inherit debug options from tunnel */ 1588 session->debug = tunnel->debug; 1589 1590 if (cfg) { 1591 session->pwtype = cfg->pw_type; 1592 session->debug = cfg->debug; 1593 session->mtu = cfg->mtu; 1594 session->mru = cfg->mru; 1595 session->send_seq = cfg->send_seq; 1596 session->recv_seq = cfg->recv_seq; 1597 session->lns_mode = cfg->lns_mode; 1598 session->reorder_timeout = cfg->reorder_timeout; 1599 session->offset = cfg->offset; 1600 session->l2specific_type = cfg->l2specific_type; 1601 session->l2specific_len = cfg->l2specific_len; 1602 session->cookie_len = cfg->cookie_len; 1603 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1604 session->peer_cookie_len = cfg->peer_cookie_len; 1605 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1606 } 1607 1608 if (tunnel->version == L2TP_HDR_VER_2) 1609 session->build_header = l2tp_build_l2tpv2_header; 1610 else 1611 session->build_header = l2tp_build_l2tpv3_header; 1612 1613 l2tp_session_set_header_len(session, tunnel->version); 1614 1615 /* Bump the reference count. The session context is deleted 1616 * only when this drops to zero. 1617 */ 1618 l2tp_session_inc_refcount(session); 1619 l2tp_tunnel_inc_refcount(tunnel); 1620 1621 /* Ensure tunnel socket isn't deleted */ 1622 sock_hold(tunnel->sock); 1623 1624 /* Add session to the tunnel's hash list */ 1625 write_lock_bh(&tunnel->hlist_lock); 1626 hlist_add_head(&session->hlist, 1627 l2tp_session_id_hash(tunnel, session_id)); 1628 write_unlock_bh(&tunnel->hlist_lock); 1629 1630 /* And to the global session list if L2TPv3 */ 1631 if (tunnel->version != L2TP_HDR_VER_2) { 1632 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1633 1634 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1635 hlist_add_head_rcu(&session->global_hlist, 1636 l2tp_session_id_hash_2(pn, session_id)); 1637 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1638 } 1639 1640 /* Ignore management session in session count value */ 1641 if (session->session_id != 0) 1642 atomic_inc(&l2tp_session_count); 1643 } 1644 1645 return session; 1646} 1647EXPORT_SYMBOL_GPL(l2tp_session_create); 1648 1649/***************************************************************************** 1650 * Init and cleanup 1651 *****************************************************************************/ 1652 1653static __net_init int l2tp_init_net(struct net *net) 1654{ 1655 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1656 int hash; 1657 1658 INIT_LIST_HEAD(&pn->l2tp_tunnel_list); 1659 spin_lock_init(&pn->l2tp_tunnel_list_lock); 1660 1661 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1662 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1663 1664 spin_lock_init(&pn->l2tp_session_hlist_lock); 1665 1666 return 0; 1667} 1668 1669static struct pernet_operations l2tp_net_ops = { 1670 .init = l2tp_init_net, 1671 .id = &l2tp_net_id, 1672 .size = sizeof(struct l2tp_net), 1673}; 1674 1675static int __init l2tp_init(void) 1676{ 1677 int rc = 0; 1678 1679 rc = register_pernet_device(&l2tp_net_ops); 1680 if (rc) 1681 goto out; 1682 1683 printk(KERN_INFO "L2TP core driver, %s\n", L2TP_DRV_VERSION); 1684 1685out: 1686 return rc; 1687} 1688 1689static void __exit l2tp_exit(void) 1690{ 1691 unregister_pernet_device(&l2tp_net_ops); 1692} 1693 1694module_init(l2tp_init); 1695module_exit(l2tp_exit); 1696 1697MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1698MODULE_DESCRIPTION("L2TP core"); 1699MODULE_LICENSE("GPL"); 1700MODULE_VERSION(L2TP_DRV_VERSION); 1701 1702