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