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 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 22 23 #include <linux/module.h> 24 #include <linux/string.h> 25 #include <linux/list.h> 26 #include <linux/rculist.h> 27 #include <linux/uaccess.h> 28 29 #include <linux/kernel.h> 30 #include <linux/spinlock.h> 31 #include <linux/kthread.h> 32 #include <linux/sched.h> 33 #include <linux/slab.h> 34 #include <linux/errno.h> 35 #include <linux/jiffies.h> 36 37 #include <linux/netdevice.h> 38 #include <linux/net.h> 39 #include <linux/inetdevice.h> 40 #include <linux/skbuff.h> 41 #include <linux/init.h> 42 #include <linux/in.h> 43 #include <linux/ip.h> 44 #include <linux/udp.h> 45 #include <linux/l2tp.h> 46 #include <linux/hash.h> 47 #include <linux/sort.h> 48 #include <linux/file.h> 49 #include <linux/nsproxy.h> 50 #include <net/net_namespace.h> 51 #include <net/netns/generic.h> 52 #include <net/dst.h> 53 #include <net/ip.h> 54 #include <net/udp.h> 55 #include <net/udp_tunnel.h> 56 #include <net/inet_common.h> 57 #include <net/xfrm.h> 58 #include <net/protocol.h> 59 #include <net/inet6_connection_sock.h> 60 #include <net/inet_ecn.h> 61 #include <net/ip6_route.h> 62 #include <net/ip6_checksum.h> 63 64 #include <asm/byteorder.h> 65 #include <linux/atomic.h> 66 67 #include "l2tp_core.h" 68 69 #define L2TP_DRV_VERSION "V2.0" 70 71 /* L2TP header constants */ 72 #define L2TP_HDRFLAG_T 0x8000 73 #define L2TP_HDRFLAG_L 0x4000 74 #define L2TP_HDRFLAG_S 0x0800 75 #define L2TP_HDRFLAG_O 0x0200 76 #define L2TP_HDRFLAG_P 0x0100 77 78 #define L2TP_HDR_VER_MASK 0x000F 79 #define L2TP_HDR_VER_2 0x0002 80 #define L2TP_HDR_VER_3 0x0003 81 82 /* L2TPv3 default L2-specific sublayer */ 83 #define L2TP_SLFLAG_S 0x40000000 84 #define L2TP_SL_SEQ_MASK 0x00ffffff 85 86 #define L2TP_HDR_SIZE_SEQ 10 87 #define L2TP_HDR_SIZE_NOSEQ 6 88 89 /* Default trace flags */ 90 #define L2TP_DEFAULT_DEBUG_FLAGS 0 91 92 /* Private data stored for received packets in the skb. 93 */ 94 struct l2tp_skb_cb { 95 u32 ns; 96 u16 has_seq; 97 u16 length; 98 unsigned long expires; 99 }; 100 101 #define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)]) 102 103 static struct workqueue_struct *l2tp_wq; 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 }; 113 114 115 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk) 116 { 117 return sk->sk_user_data; 118 } 119 120 static inline struct l2tp_net *l2tp_pernet(const struct net *net) 121 { 122 BUG_ON(!net); 123 124 return net_generic(net, l2tp_net_id); 125 } 126 127 /* Session hash global list for L2TPv3. 128 * The session_id SHOULD be random according to RFC3931, but several 129 * L2TP implementations use incrementing session_ids. So we do a real 130 * hash on the session_id, rather than a simple bitmask. 131 */ 132 static inline struct hlist_head * 133 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id) 134 { 135 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)]; 136 137 } 138 139 /* Session hash list. 140 * The session_id SHOULD be random according to RFC2661, but several 141 * L2TP implementations (Cisco and Microsoft) use incrementing 142 * session_ids. So we do a real hash on the session_id, rather than a 143 * simple bitmask. 144 */ 145 static inline struct hlist_head * 146 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id) 147 { 148 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)]; 149 } 150 151 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) 152 { 153 sock_put(tunnel->sock); 154 /* the tunnel is freed in the socket destructor */ 155 } 156 EXPORT_SYMBOL(l2tp_tunnel_free); 157 158 /* Lookup a tunnel. A new reference is held on the returned tunnel. */ 159 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) 160 { 161 const struct l2tp_net *pn = l2tp_pernet(net); 162 struct l2tp_tunnel *tunnel; 163 164 rcu_read_lock_bh(); 165 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 166 if (tunnel->tunnel_id == tunnel_id) { 167 l2tp_tunnel_inc_refcount(tunnel); 168 rcu_read_unlock_bh(); 169 170 return tunnel; 171 } 172 } 173 rcu_read_unlock_bh(); 174 175 return NULL; 176 } 177 EXPORT_SYMBOL_GPL(l2tp_tunnel_get); 178 179 /* Lookup a session. A new reference is held on the returned session. */ 180 struct l2tp_session *l2tp_session_get(const struct net *net, 181 struct l2tp_tunnel *tunnel, 182 u32 session_id) 183 { 184 struct hlist_head *session_list; 185 struct l2tp_session *session; 186 187 if (!tunnel) { 188 struct l2tp_net *pn = l2tp_pernet(net); 189 190 session_list = l2tp_session_id_hash_2(pn, session_id); 191 192 rcu_read_lock_bh(); 193 hlist_for_each_entry_rcu(session, session_list, global_hlist) { 194 if (session->session_id == session_id) { 195 l2tp_session_inc_refcount(session); 196 rcu_read_unlock_bh(); 197 198 return session; 199 } 200 } 201 rcu_read_unlock_bh(); 202 203 return NULL; 204 } 205 206 session_list = l2tp_session_id_hash(tunnel, session_id); 207 read_lock_bh(&tunnel->hlist_lock); 208 hlist_for_each_entry(session, session_list, hlist) { 209 if (session->session_id == session_id) { 210 l2tp_session_inc_refcount(session); 211 read_unlock_bh(&tunnel->hlist_lock); 212 213 return session; 214 } 215 } 216 read_unlock_bh(&tunnel->hlist_lock); 217 218 return NULL; 219 } 220 EXPORT_SYMBOL_GPL(l2tp_session_get); 221 222 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth) 223 { 224 int hash; 225 struct l2tp_session *session; 226 int count = 0; 227 228 read_lock_bh(&tunnel->hlist_lock); 229 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 230 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) { 231 if (++count > nth) { 232 l2tp_session_inc_refcount(session); 233 read_unlock_bh(&tunnel->hlist_lock); 234 return session; 235 } 236 } 237 } 238 239 read_unlock_bh(&tunnel->hlist_lock); 240 241 return NULL; 242 } 243 EXPORT_SYMBOL_GPL(l2tp_session_get_nth); 244 245 /* Lookup a session by interface name. 246 * This is very inefficient but is only used by management interfaces. 247 */ 248 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 249 const char *ifname) 250 { 251 struct l2tp_net *pn = l2tp_pernet(net); 252 int hash; 253 struct l2tp_session *session; 254 255 rcu_read_lock_bh(); 256 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { 257 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) { 258 if (!strcmp(session->ifname, ifname)) { 259 l2tp_session_inc_refcount(session); 260 rcu_read_unlock_bh(); 261 262 return session; 263 } 264 } 265 } 266 267 rcu_read_unlock_bh(); 268 269 return NULL; 270 } 271 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); 272 273 int l2tp_session_register(struct l2tp_session *session, 274 struct l2tp_tunnel *tunnel) 275 { 276 struct l2tp_session *session_walk; 277 struct hlist_head *g_head; 278 struct hlist_head *head; 279 struct l2tp_net *pn; 280 int err; 281 282 head = l2tp_session_id_hash(tunnel, session->session_id); 283 284 write_lock_bh(&tunnel->hlist_lock); 285 if (!tunnel->acpt_newsess) { 286 err = -ENODEV; 287 goto err_tlock; 288 } 289 290 hlist_for_each_entry(session_walk, head, hlist) 291 if (session_walk->session_id == session->session_id) { 292 err = -EEXIST; 293 goto err_tlock; 294 } 295 296 if (tunnel->version == L2TP_HDR_VER_3) { 297 pn = l2tp_pernet(tunnel->l2tp_net); 298 g_head = l2tp_session_id_hash_2(l2tp_pernet(tunnel->l2tp_net), 299 session->session_id); 300 301 spin_lock_bh(&pn->l2tp_session_hlist_lock); 302 303 hlist_for_each_entry(session_walk, g_head, global_hlist) 304 if (session_walk->session_id == session->session_id) { 305 err = -EEXIST; 306 goto err_tlock_pnlock; 307 } 308 309 l2tp_tunnel_inc_refcount(tunnel); 310 hlist_add_head_rcu(&session->global_hlist, g_head); 311 312 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 313 } else { 314 l2tp_tunnel_inc_refcount(tunnel); 315 } 316 317 hlist_add_head(&session->hlist, head); 318 write_unlock_bh(&tunnel->hlist_lock); 319 320 return 0; 321 322 err_tlock_pnlock: 323 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 324 err_tlock: 325 write_unlock_bh(&tunnel->hlist_lock); 326 327 return err; 328 } 329 EXPORT_SYMBOL_GPL(l2tp_session_register); 330 331 /* Lookup a tunnel by id 332 */ 333 struct l2tp_tunnel *l2tp_tunnel_find(const struct net *net, u32 tunnel_id) 334 { 335 struct l2tp_tunnel *tunnel; 336 struct l2tp_net *pn = l2tp_pernet(net); 337 338 rcu_read_lock_bh(); 339 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 340 if (tunnel->tunnel_id == tunnel_id) { 341 rcu_read_unlock_bh(); 342 return tunnel; 343 } 344 } 345 rcu_read_unlock_bh(); 346 347 return NULL; 348 } 349 EXPORT_SYMBOL_GPL(l2tp_tunnel_find); 350 351 struct l2tp_tunnel *l2tp_tunnel_find_nth(const struct net *net, int nth) 352 { 353 struct l2tp_net *pn = l2tp_pernet(net); 354 struct l2tp_tunnel *tunnel; 355 int count = 0; 356 357 rcu_read_lock_bh(); 358 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 359 if (++count > nth) { 360 rcu_read_unlock_bh(); 361 return tunnel; 362 } 363 } 364 365 rcu_read_unlock_bh(); 366 367 return NULL; 368 } 369 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth); 370 371 /***************************************************************************** 372 * Receive data handling 373 *****************************************************************************/ 374 375 /* Queue a skb in order. We come here only if the skb has an L2TP sequence 376 * number. 377 */ 378 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb) 379 { 380 struct sk_buff *skbp; 381 struct sk_buff *tmp; 382 u32 ns = L2TP_SKB_CB(skb)->ns; 383 384 spin_lock_bh(&session->reorder_q.lock); 385 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) { 386 if (L2TP_SKB_CB(skbp)->ns > ns) { 387 __skb_queue_before(&session->reorder_q, skbp, skb); 388 l2tp_dbg(session, L2TP_MSG_SEQ, 389 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n", 390 session->name, ns, L2TP_SKB_CB(skbp)->ns, 391 skb_queue_len(&session->reorder_q)); 392 atomic_long_inc(&session->stats.rx_oos_packets); 393 goto out; 394 } 395 } 396 397 __skb_queue_tail(&session->reorder_q, skb); 398 399 out: 400 spin_unlock_bh(&session->reorder_q.lock); 401 } 402 403 /* Dequeue a single skb. 404 */ 405 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb) 406 { 407 struct l2tp_tunnel *tunnel = session->tunnel; 408 int length = L2TP_SKB_CB(skb)->length; 409 410 /* We're about to requeue the skb, so return resources 411 * to its current owner (a socket receive buffer). 412 */ 413 skb_orphan(skb); 414 415 atomic_long_inc(&tunnel->stats.rx_packets); 416 atomic_long_add(length, &tunnel->stats.rx_bytes); 417 atomic_long_inc(&session->stats.rx_packets); 418 atomic_long_add(length, &session->stats.rx_bytes); 419 420 if (L2TP_SKB_CB(skb)->has_seq) { 421 /* Bump our Nr */ 422 session->nr++; 423 session->nr &= session->nr_max; 424 425 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n", 426 session->name, session->nr); 427 } 428 429 /* call private receive handler */ 430 if (session->recv_skb != NULL) 431 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); 432 else 433 kfree_skb(skb); 434 } 435 436 /* Dequeue skbs from the session's reorder_q, subject to packet order. 437 * Skbs that have been in the queue for too long are simply discarded. 438 */ 439 static void l2tp_recv_dequeue(struct l2tp_session *session) 440 { 441 struct sk_buff *skb; 442 struct sk_buff *tmp; 443 444 /* If the pkt at the head of the queue has the nr that we 445 * expect to send up next, dequeue it and any other 446 * in-sequence packets behind it. 447 */ 448 start: 449 spin_lock_bh(&session->reorder_q.lock); 450 skb_queue_walk_safe(&session->reorder_q, skb, tmp) { 451 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) { 452 atomic_long_inc(&session->stats.rx_seq_discards); 453 atomic_long_inc(&session->stats.rx_errors); 454 l2tp_dbg(session, L2TP_MSG_SEQ, 455 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n", 456 session->name, L2TP_SKB_CB(skb)->ns, 457 L2TP_SKB_CB(skb)->length, session->nr, 458 skb_queue_len(&session->reorder_q)); 459 session->reorder_skip = 1; 460 __skb_unlink(skb, &session->reorder_q); 461 kfree_skb(skb); 462 continue; 463 } 464 465 if (L2TP_SKB_CB(skb)->has_seq) { 466 if (session->reorder_skip) { 467 l2tp_dbg(session, L2TP_MSG_SEQ, 468 "%s: advancing nr to next pkt: %u -> %u", 469 session->name, session->nr, 470 L2TP_SKB_CB(skb)->ns); 471 session->reorder_skip = 0; 472 session->nr = L2TP_SKB_CB(skb)->ns; 473 } 474 if (L2TP_SKB_CB(skb)->ns != session->nr) { 475 l2tp_dbg(session, L2TP_MSG_SEQ, 476 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n", 477 session->name, L2TP_SKB_CB(skb)->ns, 478 L2TP_SKB_CB(skb)->length, session->nr, 479 skb_queue_len(&session->reorder_q)); 480 goto out; 481 } 482 } 483 __skb_unlink(skb, &session->reorder_q); 484 485 /* Process the skb. We release the queue lock while we 486 * do so to let other contexts process the queue. 487 */ 488 spin_unlock_bh(&session->reorder_q.lock); 489 l2tp_recv_dequeue_skb(session, skb); 490 goto start; 491 } 492 493 out: 494 spin_unlock_bh(&session->reorder_q.lock); 495 } 496 497 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr) 498 { 499 u32 nws; 500 501 if (nr >= session->nr) 502 nws = nr - session->nr; 503 else 504 nws = (session->nr_max + 1) - (session->nr - nr); 505 506 return nws < session->nr_window_size; 507 } 508 509 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if 510 * acceptable, else non-zero. 511 */ 512 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb) 513 { 514 if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) { 515 /* Packet sequence number is outside allowed window. 516 * Discard it. 517 */ 518 l2tp_dbg(session, L2TP_MSG_SEQ, 519 "%s: pkt %u len %d discarded, outside window, nr=%u\n", 520 session->name, L2TP_SKB_CB(skb)->ns, 521 L2TP_SKB_CB(skb)->length, session->nr); 522 goto discard; 523 } 524 525 if (session->reorder_timeout != 0) { 526 /* Packet reordering enabled. Add skb to session's 527 * reorder queue, in order of ns. 528 */ 529 l2tp_recv_queue_skb(session, skb); 530 goto out; 531 } 532 533 /* Packet reordering disabled. Discard out-of-sequence packets, while 534 * tracking the number if in-sequence packets after the first OOS packet 535 * is seen. After nr_oos_count_max in-sequence packets, reset the 536 * sequence number to re-enable packet reception. 537 */ 538 if (L2TP_SKB_CB(skb)->ns == session->nr) { 539 skb_queue_tail(&session->reorder_q, skb); 540 } else { 541 u32 nr_oos = L2TP_SKB_CB(skb)->ns; 542 u32 nr_next = (session->nr_oos + 1) & session->nr_max; 543 544 if (nr_oos == nr_next) 545 session->nr_oos_count++; 546 else 547 session->nr_oos_count = 0; 548 549 session->nr_oos = nr_oos; 550 if (session->nr_oos_count > session->nr_oos_count_max) { 551 session->reorder_skip = 1; 552 l2tp_dbg(session, L2TP_MSG_SEQ, 553 "%s: %d oos packets received. Resetting sequence numbers\n", 554 session->name, session->nr_oos_count); 555 } 556 if (!session->reorder_skip) { 557 atomic_long_inc(&session->stats.rx_seq_discards); 558 l2tp_dbg(session, L2TP_MSG_SEQ, 559 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n", 560 session->name, L2TP_SKB_CB(skb)->ns, 561 L2TP_SKB_CB(skb)->length, session->nr, 562 skb_queue_len(&session->reorder_q)); 563 goto discard; 564 } 565 skb_queue_tail(&session->reorder_q, skb); 566 } 567 568 out: 569 return 0; 570 571 discard: 572 return 1; 573 } 574 575 /* Do receive processing of L2TP data frames. We handle both L2TPv2 576 * and L2TPv3 data frames here. 577 * 578 * L2TPv2 Data Message Header 579 * 580 * 0 1 2 3 581 * 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 1 582 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 583 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) | 584 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 585 * | Tunnel ID | Session ID | 586 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 587 * | Ns (opt) | Nr (opt) | 588 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 589 * | Offset Size (opt) | Offset pad... (opt) 590 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 591 * 592 * Data frames are marked by T=0. All other fields are the same as 593 * those in L2TP control frames. 594 * 595 * L2TPv3 Data Message Header 596 * 597 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 598 * | L2TP Session Header | 599 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 600 * | L2-Specific Sublayer | 601 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 602 * | Tunnel Payload ... 603 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 604 * 605 * L2TPv3 Session Header Over IP 606 * 607 * 0 1 2 3 608 * 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 1 609 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 610 * | Session ID | 611 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 612 * | Cookie (optional, maximum 64 bits)... 613 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 614 * | 615 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 616 * 617 * L2TPv3 L2-Specific Sublayer Format 618 * 619 * 0 1 2 3 620 * 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 1 621 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 622 * |x|S|x|x|x|x|x|x| Sequence Number | 623 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 624 * 625 * Cookie value and sublayer format are negotiated with the peer when 626 * the session is set up. Unlike L2TPv2, we do not need to parse the 627 * packet header to determine if optional fields are present. 628 * 629 * Caller must already have parsed the frame and determined that it is 630 * a data (not control) frame before coming here. Fields up to the 631 * session-id have already been parsed and ptr points to the data 632 * after the session-id. 633 */ 634 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 635 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 636 int length, int (*payload_hook)(struct sk_buff *skb)) 637 { 638 struct l2tp_tunnel *tunnel = session->tunnel; 639 int offset; 640 u32 ns, nr; 641 642 /* Parse and check optional cookie */ 643 if (session->peer_cookie_len > 0) { 644 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { 645 l2tp_info(tunnel, L2TP_MSG_DATA, 646 "%s: cookie mismatch (%u/%u). Discarding.\n", 647 tunnel->name, tunnel->tunnel_id, 648 session->session_id); 649 atomic_long_inc(&session->stats.rx_cookie_discards); 650 goto discard; 651 } 652 ptr += session->peer_cookie_len; 653 } 654 655 /* Handle the optional sequence numbers. Sequence numbers are 656 * in different places for L2TPv2 and L2TPv3. 657 * 658 * If we are the LAC, enable/disable sequence numbers under 659 * the control of the LNS. If no sequence numbers present but 660 * we were expecting them, discard frame. 661 */ 662 ns = nr = 0; 663 L2TP_SKB_CB(skb)->has_seq = 0; 664 if (tunnel->version == L2TP_HDR_VER_2) { 665 if (hdrflags & L2TP_HDRFLAG_S) { 666 ns = ntohs(*(__be16 *) ptr); 667 ptr += 2; 668 nr = ntohs(*(__be16 *) ptr); 669 ptr += 2; 670 671 /* Store L2TP info in the skb */ 672 L2TP_SKB_CB(skb)->ns = ns; 673 L2TP_SKB_CB(skb)->has_seq = 1; 674 675 l2tp_dbg(session, L2TP_MSG_SEQ, 676 "%s: recv data ns=%u, nr=%u, session nr=%u\n", 677 session->name, ns, nr, session->nr); 678 } 679 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 680 u32 l2h = ntohl(*(__be32 *) ptr); 681 682 if (l2h & 0x40000000) { 683 ns = l2h & 0x00ffffff; 684 685 /* Store L2TP info in the skb */ 686 L2TP_SKB_CB(skb)->ns = ns; 687 L2TP_SKB_CB(skb)->has_seq = 1; 688 689 l2tp_dbg(session, L2TP_MSG_SEQ, 690 "%s: recv data ns=%u, session nr=%u\n", 691 session->name, ns, session->nr); 692 } 693 ptr += 4; 694 } 695 696 if (L2TP_SKB_CB(skb)->has_seq) { 697 /* Received a packet with sequence numbers. If we're the LNS, 698 * check if we sre sending sequence numbers and if not, 699 * configure it so. 700 */ 701 if ((!session->lns_mode) && (!session->send_seq)) { 702 l2tp_info(session, L2TP_MSG_SEQ, 703 "%s: requested to enable seq numbers by LNS\n", 704 session->name); 705 session->send_seq = 1; 706 l2tp_session_set_header_len(session, tunnel->version); 707 } 708 } else { 709 /* No sequence numbers. 710 * If user has configured mandatory sequence numbers, discard. 711 */ 712 if (session->recv_seq) { 713 l2tp_warn(session, L2TP_MSG_SEQ, 714 "%s: recv data has no seq numbers when required. Discarding.\n", 715 session->name); 716 atomic_long_inc(&session->stats.rx_seq_discards); 717 goto discard; 718 } 719 720 /* If we're the LAC and we're sending sequence numbers, the 721 * LNS has requested that we no longer send sequence numbers. 722 * If we're the LNS and we're sending sequence numbers, the 723 * LAC is broken. Discard the frame. 724 */ 725 if ((!session->lns_mode) && (session->send_seq)) { 726 l2tp_info(session, L2TP_MSG_SEQ, 727 "%s: requested to disable seq numbers by LNS\n", 728 session->name); 729 session->send_seq = 0; 730 l2tp_session_set_header_len(session, tunnel->version); 731 } else if (session->send_seq) { 732 l2tp_warn(session, L2TP_MSG_SEQ, 733 "%s: recv data has no seq numbers when required. Discarding.\n", 734 session->name); 735 atomic_long_inc(&session->stats.rx_seq_discards); 736 goto discard; 737 } 738 } 739 740 /* Session data offset is defined only for L2TPv2 and is 741 * indicated by an optional 16-bit value in the header. 742 */ 743 if (tunnel->version == L2TP_HDR_VER_2) { 744 /* If offset bit set, skip it. */ 745 if (hdrflags & L2TP_HDRFLAG_O) { 746 offset = ntohs(*(__be16 *)ptr); 747 ptr += 2 + offset; 748 } 749 } 750 751 offset = ptr - optr; 752 if (!pskb_may_pull(skb, offset)) 753 goto discard; 754 755 __skb_pull(skb, offset); 756 757 /* If caller wants to process the payload before we queue the 758 * packet, do so now. 759 */ 760 if (payload_hook) 761 if ((*payload_hook)(skb)) 762 goto discard; 763 764 /* Prepare skb for adding to the session's reorder_q. Hold 765 * packets for max reorder_timeout or 1 second if not 766 * reordering. 767 */ 768 L2TP_SKB_CB(skb)->length = length; 769 L2TP_SKB_CB(skb)->expires = jiffies + 770 (session->reorder_timeout ? session->reorder_timeout : HZ); 771 772 /* Add packet to the session's receive queue. Reordering is done here, if 773 * enabled. Saved L2TP protocol info is stored in skb->sb[]. 774 */ 775 if (L2TP_SKB_CB(skb)->has_seq) { 776 if (l2tp_recv_data_seq(session, skb)) 777 goto discard; 778 } else { 779 /* No sequence numbers. Add the skb to the tail of the 780 * reorder queue. This ensures that it will be 781 * delivered after all previous sequenced skbs. 782 */ 783 skb_queue_tail(&session->reorder_q, skb); 784 } 785 786 /* Try to dequeue as many skbs from reorder_q as we can. */ 787 l2tp_recv_dequeue(session); 788 789 return; 790 791 discard: 792 atomic_long_inc(&session->stats.rx_errors); 793 kfree_skb(skb); 794 } 795 EXPORT_SYMBOL(l2tp_recv_common); 796 797 /* Drop skbs from the session's reorder_q 798 */ 799 int l2tp_session_queue_purge(struct l2tp_session *session) 800 { 801 struct sk_buff *skb = NULL; 802 BUG_ON(!session); 803 BUG_ON(session->magic != L2TP_SESSION_MAGIC); 804 while ((skb = skb_dequeue(&session->reorder_q))) { 805 atomic_long_inc(&session->stats.rx_errors); 806 kfree_skb(skb); 807 } 808 return 0; 809 } 810 EXPORT_SYMBOL_GPL(l2tp_session_queue_purge); 811 812 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame 813 * here. The skb is not on a list when we get here. 814 * Returns 0 if the packet was a data packet and was successfully passed on. 815 * Returns 1 if the packet was not a good data packet and could not be 816 * forwarded. All such packets are passed up to userspace to deal with. 817 */ 818 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, 819 int (*payload_hook)(struct sk_buff *skb)) 820 { 821 struct l2tp_session *session = NULL; 822 unsigned char *ptr, *optr; 823 u16 hdrflags; 824 u32 tunnel_id, session_id; 825 u16 version; 826 int length; 827 828 /* UDP has verifed checksum */ 829 830 /* UDP always verifies the packet length. */ 831 __skb_pull(skb, sizeof(struct udphdr)); 832 833 /* Short packet? */ 834 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) { 835 l2tp_info(tunnel, L2TP_MSG_DATA, 836 "%s: recv short packet (len=%d)\n", 837 tunnel->name, skb->len); 838 goto error; 839 } 840 841 /* Trace packet contents, if enabled */ 842 if (tunnel->debug & L2TP_MSG_DATA) { 843 length = min(32u, skb->len); 844 if (!pskb_may_pull(skb, length)) 845 goto error; 846 847 pr_debug("%s: recv\n", tunnel->name); 848 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 849 } 850 851 /* Point to L2TP header */ 852 optr = ptr = skb->data; 853 854 /* Get L2TP header flags */ 855 hdrflags = ntohs(*(__be16 *) ptr); 856 857 /* Check protocol version */ 858 version = hdrflags & L2TP_HDR_VER_MASK; 859 if (version != tunnel->version) { 860 l2tp_info(tunnel, L2TP_MSG_DATA, 861 "%s: recv protocol version mismatch: got %d expected %d\n", 862 tunnel->name, version, tunnel->version); 863 goto error; 864 } 865 866 /* Get length of L2TP packet */ 867 length = skb->len; 868 869 /* If type is control packet, it is handled by userspace. */ 870 if (hdrflags & L2TP_HDRFLAG_T) { 871 l2tp_dbg(tunnel, L2TP_MSG_DATA, 872 "%s: recv control packet, len=%d\n", 873 tunnel->name, length); 874 goto error; 875 } 876 877 /* Skip flags */ 878 ptr += 2; 879 880 if (tunnel->version == L2TP_HDR_VER_2) { 881 /* If length is present, skip it */ 882 if (hdrflags & L2TP_HDRFLAG_L) 883 ptr += 2; 884 885 /* Extract tunnel and session ID */ 886 tunnel_id = ntohs(*(__be16 *) ptr); 887 ptr += 2; 888 session_id = ntohs(*(__be16 *) ptr); 889 ptr += 2; 890 } else { 891 ptr += 2; /* skip reserved bits */ 892 tunnel_id = tunnel->tunnel_id; 893 session_id = ntohl(*(__be32 *) ptr); 894 ptr += 4; 895 } 896 897 /* Find the session context */ 898 session = l2tp_session_get(tunnel->l2tp_net, tunnel, session_id); 899 if (!session || !session->recv_skb) { 900 if (session) 901 l2tp_session_dec_refcount(session); 902 903 /* Not found? Pass to userspace to deal with */ 904 l2tp_info(tunnel, L2TP_MSG_DATA, 905 "%s: no session found (%u/%u). Passing up.\n", 906 tunnel->name, tunnel_id, session_id); 907 goto error; 908 } 909 910 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook); 911 l2tp_session_dec_refcount(session); 912 913 return 0; 914 915 error: 916 /* Put UDP header back */ 917 __skb_push(skb, sizeof(struct udphdr)); 918 919 return 1; 920 } 921 922 /* UDP encapsulation receive handler. See net/ipv4/udp.c. 923 * Return codes: 924 * 0 : success. 925 * <0: error 926 * >0: skb should be passed up to userspace as UDP. 927 */ 928 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 929 { 930 struct l2tp_tunnel *tunnel; 931 932 tunnel = l2tp_tunnel(sk); 933 if (tunnel == NULL) 934 goto pass_up; 935 936 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n", 937 tunnel->name, skb->len); 938 939 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook)) 940 goto pass_up; 941 942 return 0; 943 944 pass_up: 945 return 1; 946 } 947 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 948 949 /************************************************************************ 950 * Transmit handling 951 ***********************************************************************/ 952 953 /* Build an L2TP header for the session into the buffer provided. 954 */ 955 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 956 { 957 struct l2tp_tunnel *tunnel = session->tunnel; 958 __be16 *bufp = buf; 959 __be16 *optr = buf; 960 u16 flags = L2TP_HDR_VER_2; 961 u32 tunnel_id = tunnel->peer_tunnel_id; 962 u32 session_id = session->peer_session_id; 963 964 if (session->send_seq) 965 flags |= L2TP_HDRFLAG_S; 966 967 /* Setup L2TP header. */ 968 *bufp++ = htons(flags); 969 *bufp++ = htons(tunnel_id); 970 *bufp++ = htons(session_id); 971 if (session->send_seq) { 972 *bufp++ = htons(session->ns); 973 *bufp++ = 0; 974 session->ns++; 975 session->ns &= 0xffff; 976 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n", 977 session->name, session->ns); 978 } 979 980 return bufp - optr; 981 } 982 983 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 984 { 985 struct l2tp_tunnel *tunnel = session->tunnel; 986 char *bufp = buf; 987 char *optr = bufp; 988 989 /* Setup L2TP header. The header differs slightly for UDP and 990 * IP encapsulations. For UDP, there is 4 bytes of flags. 991 */ 992 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 993 u16 flags = L2TP_HDR_VER_3; 994 *((__be16 *) bufp) = htons(flags); 995 bufp += 2; 996 *((__be16 *) bufp) = 0; 997 bufp += 2; 998 } 999 1000 *((__be32 *) bufp) = htonl(session->peer_session_id); 1001 bufp += 4; 1002 if (session->cookie_len) { 1003 memcpy(bufp, &session->cookie[0], session->cookie_len); 1004 bufp += session->cookie_len; 1005 } 1006 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 1007 u32 l2h = 0; 1008 1009 if (session->send_seq) { 1010 l2h = 0x40000000 | session->ns; 1011 session->ns++; 1012 session->ns &= 0xffffff; 1013 l2tp_dbg(session, L2TP_MSG_SEQ, 1014 "%s: updated ns to %u\n", 1015 session->name, session->ns); 1016 } 1017 1018 *((__be32 *)bufp) = htonl(l2h); 1019 bufp += 4; 1020 } 1021 1022 return bufp - optr; 1023 } 1024 1025 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, 1026 struct flowi *fl, size_t data_len) 1027 { 1028 struct l2tp_tunnel *tunnel = session->tunnel; 1029 unsigned int len = skb->len; 1030 int error; 1031 1032 /* Debug */ 1033 if (session->send_seq) 1034 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes, ns=%u\n", 1035 session->name, data_len, session->ns - 1); 1036 else 1037 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes\n", 1038 session->name, data_len); 1039 1040 if (session->debug & L2TP_MSG_DATA) { 1041 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1042 unsigned char *datap = skb->data + uhlen; 1043 1044 pr_debug("%s: xmit\n", session->name); 1045 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, 1046 datap, min_t(size_t, 32, len - uhlen)); 1047 } 1048 1049 /* Queue the packet to IP for output */ 1050 skb->ignore_df = 1; 1051 #if IS_ENABLED(CONFIG_IPV6) 1052 if (tunnel->sock->sk_family == PF_INET6 && !tunnel->v4mapped) 1053 error = inet6_csk_xmit(tunnel->sock, skb, NULL); 1054 else 1055 #endif 1056 error = ip_queue_xmit(tunnel->sock, skb, fl); 1057 1058 /* Update stats */ 1059 if (error >= 0) { 1060 atomic_long_inc(&tunnel->stats.tx_packets); 1061 atomic_long_add(len, &tunnel->stats.tx_bytes); 1062 atomic_long_inc(&session->stats.tx_packets); 1063 atomic_long_add(len, &session->stats.tx_bytes); 1064 } else { 1065 atomic_long_inc(&tunnel->stats.tx_errors); 1066 atomic_long_inc(&session->stats.tx_errors); 1067 } 1068 1069 return 0; 1070 } 1071 1072 /* If caller requires the skb to have a ppp header, the header must be 1073 * inserted in the skb data before calling this function. 1074 */ 1075 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len) 1076 { 1077 int data_len = skb->len; 1078 struct l2tp_tunnel *tunnel = session->tunnel; 1079 struct sock *sk = tunnel->sock; 1080 struct flowi *fl; 1081 struct udphdr *uh; 1082 struct inet_sock *inet; 1083 int headroom; 1084 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1085 int udp_len; 1086 int ret = NET_XMIT_SUCCESS; 1087 1088 /* Check that there's enough headroom in the skb to insert IP, 1089 * UDP and L2TP headers. If not enough, expand it to 1090 * make room. Adjust truesize. 1091 */ 1092 headroom = NET_SKB_PAD + sizeof(struct iphdr) + 1093 uhlen + hdr_len; 1094 if (skb_cow_head(skb, headroom)) { 1095 kfree_skb(skb); 1096 return NET_XMIT_DROP; 1097 } 1098 1099 /* Setup L2TP header */ 1100 session->build_header(session, __skb_push(skb, hdr_len)); 1101 1102 /* Reset skb netfilter state */ 1103 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1104 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | 1105 IPSKB_REROUTED); 1106 nf_reset(skb); 1107 1108 bh_lock_sock(sk); 1109 if (sock_owned_by_user(sk)) { 1110 kfree_skb(skb); 1111 ret = NET_XMIT_DROP; 1112 goto out_unlock; 1113 } 1114 1115 /* Get routing info from the tunnel socket */ 1116 skb_dst_drop(skb); 1117 skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0))); 1118 1119 inet = inet_sk(sk); 1120 fl = &inet->cork.fl; 1121 switch (tunnel->encap) { 1122 case L2TP_ENCAPTYPE_UDP: 1123 /* Setup UDP header */ 1124 __skb_push(skb, sizeof(*uh)); 1125 skb_reset_transport_header(skb); 1126 uh = udp_hdr(skb); 1127 uh->source = inet->inet_sport; 1128 uh->dest = inet->inet_dport; 1129 udp_len = uhlen + hdr_len + data_len; 1130 uh->len = htons(udp_len); 1131 1132 /* Calculate UDP checksum if configured to do so */ 1133 #if IS_ENABLED(CONFIG_IPV6) 1134 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped) 1135 udp6_set_csum(udp_get_no_check6_tx(sk), 1136 skb, &inet6_sk(sk)->saddr, 1137 &sk->sk_v6_daddr, udp_len); 1138 else 1139 #endif 1140 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr, 1141 inet->inet_daddr, udp_len); 1142 break; 1143 1144 case L2TP_ENCAPTYPE_IP: 1145 break; 1146 } 1147 1148 l2tp_xmit_core(session, skb, fl, data_len); 1149 out_unlock: 1150 bh_unlock_sock(sk); 1151 1152 return ret; 1153 } 1154 EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1155 1156 /***************************************************************************** 1157 * Tinnel and session create/destroy. 1158 *****************************************************************************/ 1159 1160 /* Tunnel socket destruct hook. 1161 * The tunnel context is deleted only when all session sockets have been 1162 * closed. 1163 */ 1164 static void l2tp_tunnel_destruct(struct sock *sk) 1165 { 1166 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1167 1168 if (tunnel == NULL) 1169 goto end; 1170 1171 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name); 1172 1173 /* Disable udp encapsulation */ 1174 switch (tunnel->encap) { 1175 case L2TP_ENCAPTYPE_UDP: 1176 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1177 (udp_sk(sk))->encap_type = 0; 1178 (udp_sk(sk))->encap_rcv = NULL; 1179 (udp_sk(sk))->encap_destroy = NULL; 1180 break; 1181 case L2TP_ENCAPTYPE_IP: 1182 break; 1183 } 1184 1185 /* Remove hooks into tunnel socket */ 1186 sk->sk_destruct = tunnel->old_sk_destruct; 1187 sk->sk_user_data = NULL; 1188 1189 /* Call the original destructor */ 1190 if (sk->sk_destruct) 1191 (*sk->sk_destruct)(sk); 1192 1193 kfree_rcu(tunnel, rcu); 1194 end: 1195 return; 1196 } 1197 1198 /* When the tunnel is closed, all the attached sessions need to go too. 1199 */ 1200 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1201 { 1202 int hash; 1203 struct hlist_node *walk; 1204 struct hlist_node *tmp; 1205 struct l2tp_session *session; 1206 1207 BUG_ON(tunnel == NULL); 1208 1209 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n", 1210 tunnel->name); 1211 1212 write_lock_bh(&tunnel->hlist_lock); 1213 tunnel->acpt_newsess = false; 1214 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1215 again: 1216 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) { 1217 session = hlist_entry(walk, struct l2tp_session, hlist); 1218 1219 l2tp_info(session, L2TP_MSG_CONTROL, 1220 "%s: closing session\n", session->name); 1221 1222 hlist_del_init(&session->hlist); 1223 1224 if (test_and_set_bit(0, &session->dead)) 1225 goto again; 1226 1227 write_unlock_bh(&tunnel->hlist_lock); 1228 1229 __l2tp_session_unhash(session); 1230 l2tp_session_queue_purge(session); 1231 1232 if (session->session_close != NULL) 1233 (*session->session_close)(session); 1234 1235 l2tp_session_dec_refcount(session); 1236 1237 write_lock_bh(&tunnel->hlist_lock); 1238 1239 /* Now restart from the beginning of this hash 1240 * chain. We always remove a session from the 1241 * list so we are guaranteed to make forward 1242 * progress. 1243 */ 1244 goto again; 1245 } 1246 } 1247 write_unlock_bh(&tunnel->hlist_lock); 1248 } 1249 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall); 1250 1251 /* Tunnel socket destroy hook for UDP encapsulation */ 1252 static void l2tp_udp_encap_destroy(struct sock *sk) 1253 { 1254 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1255 1256 if (tunnel) 1257 l2tp_tunnel_delete(tunnel); 1258 } 1259 1260 /* Workqueue tunnel deletion function */ 1261 static void l2tp_tunnel_del_work(struct work_struct *work) 1262 { 1263 struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, 1264 del_work); 1265 struct sock *sk = tunnel->sock; 1266 struct socket *sock = sk->sk_socket; 1267 struct l2tp_net *pn; 1268 1269 l2tp_tunnel_closeall(tunnel); 1270 1271 /* If the tunnel socket was created within the kernel, use 1272 * the sk API to release it here. 1273 */ 1274 if (tunnel->fd < 0) { 1275 if (sock) { 1276 kernel_sock_shutdown(sock, SHUT_RDWR); 1277 sock_release(sock); 1278 } 1279 } 1280 1281 /* Remove the tunnel struct from the tunnel list */ 1282 pn = l2tp_pernet(tunnel->l2tp_net); 1283 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1284 list_del_rcu(&tunnel->list); 1285 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1286 1287 /* drop initial ref */ 1288 l2tp_tunnel_dec_refcount(tunnel); 1289 1290 /* drop workqueue ref */ 1291 l2tp_tunnel_dec_refcount(tunnel); 1292 } 1293 1294 /* Create a socket for the tunnel, if one isn't set up by 1295 * userspace. This is used for static tunnels where there is no 1296 * managing L2TP daemon. 1297 * 1298 * Since we don't want these sockets to keep a namespace alive by 1299 * themselves, we drop the socket's namespace refcount after creation. 1300 * These sockets are freed when the namespace exits using the pernet 1301 * exit hook. 1302 */ 1303 static int l2tp_tunnel_sock_create(struct net *net, 1304 u32 tunnel_id, 1305 u32 peer_tunnel_id, 1306 struct l2tp_tunnel_cfg *cfg, 1307 struct socket **sockp) 1308 { 1309 int err = -EINVAL; 1310 struct socket *sock = NULL; 1311 struct udp_port_cfg udp_conf; 1312 1313 switch (cfg->encap) { 1314 case L2TP_ENCAPTYPE_UDP: 1315 memset(&udp_conf, 0, sizeof(udp_conf)); 1316 1317 #if IS_ENABLED(CONFIG_IPV6) 1318 if (cfg->local_ip6 && cfg->peer_ip6) { 1319 udp_conf.family = AF_INET6; 1320 memcpy(&udp_conf.local_ip6, cfg->local_ip6, 1321 sizeof(udp_conf.local_ip6)); 1322 memcpy(&udp_conf.peer_ip6, cfg->peer_ip6, 1323 sizeof(udp_conf.peer_ip6)); 1324 udp_conf.use_udp6_tx_checksums = 1325 ! cfg->udp6_zero_tx_checksums; 1326 udp_conf.use_udp6_rx_checksums = 1327 ! cfg->udp6_zero_rx_checksums; 1328 } else 1329 #endif 1330 { 1331 udp_conf.family = AF_INET; 1332 udp_conf.local_ip = cfg->local_ip; 1333 udp_conf.peer_ip = cfg->peer_ip; 1334 udp_conf.use_udp_checksums = cfg->use_udp_checksums; 1335 } 1336 1337 udp_conf.local_udp_port = htons(cfg->local_udp_port); 1338 udp_conf.peer_udp_port = htons(cfg->peer_udp_port); 1339 1340 err = udp_sock_create(net, &udp_conf, &sock); 1341 if (err < 0) 1342 goto out; 1343 1344 break; 1345 1346 case L2TP_ENCAPTYPE_IP: 1347 #if IS_ENABLED(CONFIG_IPV6) 1348 if (cfg->local_ip6 && cfg->peer_ip6) { 1349 struct sockaddr_l2tpip6 ip6_addr = {0}; 1350 1351 err = sock_create_kern(net, AF_INET6, SOCK_DGRAM, 1352 IPPROTO_L2TP, &sock); 1353 if (err < 0) 1354 goto out; 1355 1356 ip6_addr.l2tp_family = AF_INET6; 1357 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6, 1358 sizeof(ip6_addr.l2tp_addr)); 1359 ip6_addr.l2tp_conn_id = tunnel_id; 1360 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr, 1361 sizeof(ip6_addr)); 1362 if (err < 0) 1363 goto out; 1364 1365 ip6_addr.l2tp_family = AF_INET6; 1366 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6, 1367 sizeof(ip6_addr.l2tp_addr)); 1368 ip6_addr.l2tp_conn_id = peer_tunnel_id; 1369 err = kernel_connect(sock, 1370 (struct sockaddr *) &ip6_addr, 1371 sizeof(ip6_addr), 0); 1372 if (err < 0) 1373 goto out; 1374 } else 1375 #endif 1376 { 1377 struct sockaddr_l2tpip ip_addr = {0}; 1378 1379 err = sock_create_kern(net, AF_INET, SOCK_DGRAM, 1380 IPPROTO_L2TP, &sock); 1381 if (err < 0) 1382 goto out; 1383 1384 ip_addr.l2tp_family = AF_INET; 1385 ip_addr.l2tp_addr = cfg->local_ip; 1386 ip_addr.l2tp_conn_id = tunnel_id; 1387 err = kernel_bind(sock, (struct sockaddr *) &ip_addr, 1388 sizeof(ip_addr)); 1389 if (err < 0) 1390 goto out; 1391 1392 ip_addr.l2tp_family = AF_INET; 1393 ip_addr.l2tp_addr = cfg->peer_ip; 1394 ip_addr.l2tp_conn_id = peer_tunnel_id; 1395 err = kernel_connect(sock, (struct sockaddr *) &ip_addr, 1396 sizeof(ip_addr), 0); 1397 if (err < 0) 1398 goto out; 1399 } 1400 break; 1401 1402 default: 1403 goto out; 1404 } 1405 1406 out: 1407 *sockp = sock; 1408 if ((err < 0) && sock) { 1409 kernel_sock_shutdown(sock, SHUT_RDWR); 1410 sock_release(sock); 1411 *sockp = NULL; 1412 } 1413 1414 return err; 1415 } 1416 1417 static struct lock_class_key l2tp_socket_class; 1418 1419 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) 1420 { 1421 struct l2tp_tunnel *tunnel = NULL; 1422 int err; 1423 struct socket *sock = NULL; 1424 struct sock *sk = NULL; 1425 struct l2tp_net *pn; 1426 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1427 1428 /* Get the tunnel socket from the fd, which was opened by 1429 * the userspace L2TP daemon. If not specified, create a 1430 * kernel socket. 1431 */ 1432 if (fd < 0) { 1433 err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id, 1434 cfg, &sock); 1435 if (err < 0) 1436 goto err; 1437 } else { 1438 sock = sockfd_lookup(fd, &err); 1439 if (!sock) { 1440 pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n", 1441 tunnel_id, fd, err); 1442 err = -EBADF; 1443 goto err; 1444 } 1445 1446 /* Reject namespace mismatches */ 1447 if (!net_eq(sock_net(sock->sk), net)) { 1448 pr_err("tunl %u: netns mismatch\n", tunnel_id); 1449 err = -EINVAL; 1450 goto err; 1451 } 1452 } 1453 1454 sk = sock->sk; 1455 1456 if (cfg != NULL) 1457 encap = cfg->encap; 1458 1459 /* Quick sanity checks */ 1460 switch (encap) { 1461 case L2TP_ENCAPTYPE_UDP: 1462 err = -EPROTONOSUPPORT; 1463 if (sk->sk_protocol != IPPROTO_UDP) { 1464 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n", 1465 tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP); 1466 goto err; 1467 } 1468 break; 1469 case L2TP_ENCAPTYPE_IP: 1470 err = -EPROTONOSUPPORT; 1471 if (sk->sk_protocol != IPPROTO_L2TP) { 1472 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n", 1473 tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP); 1474 goto err; 1475 } 1476 break; 1477 } 1478 1479 /* Check if this socket has already been prepped */ 1480 tunnel = l2tp_tunnel(sk); 1481 if (tunnel != NULL) { 1482 /* This socket has already been prepped */ 1483 err = -EBUSY; 1484 goto err; 1485 } 1486 1487 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL); 1488 if (tunnel == NULL) { 1489 err = -ENOMEM; 1490 goto err; 1491 } 1492 1493 tunnel->version = version; 1494 tunnel->tunnel_id = tunnel_id; 1495 tunnel->peer_tunnel_id = peer_tunnel_id; 1496 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS; 1497 1498 tunnel->magic = L2TP_TUNNEL_MAGIC; 1499 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1500 rwlock_init(&tunnel->hlist_lock); 1501 tunnel->acpt_newsess = true; 1502 1503 /* The net we belong to */ 1504 tunnel->l2tp_net = net; 1505 pn = l2tp_pernet(net); 1506 1507 if (cfg != NULL) 1508 tunnel->debug = cfg->debug; 1509 1510 #if IS_ENABLED(CONFIG_IPV6) 1511 if (sk->sk_family == PF_INET6) { 1512 struct ipv6_pinfo *np = inet6_sk(sk); 1513 1514 if (ipv6_addr_v4mapped(&np->saddr) && 1515 ipv6_addr_v4mapped(&sk->sk_v6_daddr)) { 1516 struct inet_sock *inet = inet_sk(sk); 1517 1518 tunnel->v4mapped = true; 1519 inet->inet_saddr = np->saddr.s6_addr32[3]; 1520 inet->inet_rcv_saddr = sk->sk_v6_rcv_saddr.s6_addr32[3]; 1521 inet->inet_daddr = sk->sk_v6_daddr.s6_addr32[3]; 1522 } else { 1523 tunnel->v4mapped = false; 1524 } 1525 } 1526 #endif 1527 1528 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */ 1529 tunnel->encap = encap; 1530 if (encap == L2TP_ENCAPTYPE_UDP) { 1531 struct udp_tunnel_sock_cfg udp_cfg = { }; 1532 1533 udp_cfg.sk_user_data = tunnel; 1534 udp_cfg.encap_type = UDP_ENCAP_L2TPINUDP; 1535 udp_cfg.encap_rcv = l2tp_udp_encap_recv; 1536 udp_cfg.encap_destroy = l2tp_udp_encap_destroy; 1537 1538 setup_udp_tunnel_sock(net, sock, &udp_cfg); 1539 } else { 1540 sk->sk_user_data = tunnel; 1541 } 1542 1543 /* Bump the reference count. The tunnel context is deleted 1544 * only when this drops to zero. A reference is also held on 1545 * the tunnel socket to ensure that it is not released while 1546 * the tunnel is extant. Must be done before sk_destruct is 1547 * set. 1548 */ 1549 refcount_set(&tunnel->ref_count, 1); 1550 sock_hold(sk); 1551 tunnel->sock = sk; 1552 tunnel->fd = fd; 1553 1554 /* Hook on the tunnel socket destructor so that we can cleanup 1555 * if the tunnel socket goes away. 1556 */ 1557 tunnel->old_sk_destruct = sk->sk_destruct; 1558 sk->sk_destruct = &l2tp_tunnel_destruct; 1559 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock"); 1560 1561 sk->sk_allocation = GFP_ATOMIC; 1562 1563 /* Init delete workqueue struct */ 1564 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); 1565 1566 /* Add tunnel to our list */ 1567 INIT_LIST_HEAD(&tunnel->list); 1568 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1569 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); 1570 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1571 1572 err = 0; 1573 err: 1574 if (tunnelp) 1575 *tunnelp = tunnel; 1576 1577 /* If tunnel's socket was created by the kernel, it doesn't 1578 * have a file. 1579 */ 1580 if (sock && sock->file) 1581 sockfd_put(sock); 1582 1583 return err; 1584 } 1585 EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1586 1587 /* This function is used by the netlink TUNNEL_DELETE command. 1588 */ 1589 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1590 { 1591 if (!test_and_set_bit(0, &tunnel->dead)) { 1592 l2tp_tunnel_inc_refcount(tunnel); 1593 queue_work(l2tp_wq, &tunnel->del_work); 1594 } 1595 } 1596 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1597 1598 /* Really kill the session. 1599 */ 1600 void l2tp_session_free(struct l2tp_session *session) 1601 { 1602 struct l2tp_tunnel *tunnel = session->tunnel; 1603 1604 BUG_ON(refcount_read(&session->ref_count) != 0); 1605 1606 if (tunnel) { 1607 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC); 1608 l2tp_tunnel_dec_refcount(tunnel); 1609 } 1610 1611 kfree(session); 1612 } 1613 EXPORT_SYMBOL_GPL(l2tp_session_free); 1614 1615 /* Remove an l2tp session from l2tp_core's hash lists. 1616 * Provides a tidyup interface for pseudowire code which can't just route all 1617 * shutdown via. l2tp_session_delete and a pseudowire-specific session_close 1618 * callback. 1619 */ 1620 void __l2tp_session_unhash(struct l2tp_session *session) 1621 { 1622 struct l2tp_tunnel *tunnel = session->tunnel; 1623 1624 /* Remove the session from core hashes */ 1625 if (tunnel) { 1626 /* Remove from the per-tunnel hash */ 1627 write_lock_bh(&tunnel->hlist_lock); 1628 hlist_del_init(&session->hlist); 1629 write_unlock_bh(&tunnel->hlist_lock); 1630 1631 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1632 if (tunnel->version != L2TP_HDR_VER_2) { 1633 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1634 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1635 hlist_del_init_rcu(&session->global_hlist); 1636 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1637 synchronize_rcu(); 1638 } 1639 } 1640 } 1641 EXPORT_SYMBOL_GPL(__l2tp_session_unhash); 1642 1643 /* This function is used by the netlink SESSION_DELETE command and by 1644 pseudowire modules. 1645 */ 1646 int l2tp_session_delete(struct l2tp_session *session) 1647 { 1648 if (test_and_set_bit(0, &session->dead)) 1649 return 0; 1650 1651 __l2tp_session_unhash(session); 1652 l2tp_session_queue_purge(session); 1653 if (session->session_close != NULL) 1654 (*session->session_close)(session); 1655 1656 l2tp_session_dec_refcount(session); 1657 1658 return 0; 1659 } 1660 EXPORT_SYMBOL_GPL(l2tp_session_delete); 1661 1662 /* We come here whenever a session's send_seq, cookie_len or 1663 * l2specific_type parameters are set. 1664 */ 1665 void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1666 { 1667 if (version == L2TP_HDR_VER_2) { 1668 session->hdr_len = 6; 1669 if (session->send_seq) 1670 session->hdr_len += 4; 1671 } else { 1672 session->hdr_len = 4 + session->cookie_len; 1673 session->hdr_len += l2tp_get_l2specific_len(session); 1674 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1675 session->hdr_len += 4; 1676 } 1677 1678 } 1679 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1680 1681 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) 1682 { 1683 struct l2tp_session *session; 1684 1685 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL); 1686 if (session != NULL) { 1687 session->magic = L2TP_SESSION_MAGIC; 1688 session->tunnel = tunnel; 1689 1690 session->session_id = session_id; 1691 session->peer_session_id = peer_session_id; 1692 session->nr = 0; 1693 if (tunnel->version == L2TP_HDR_VER_2) 1694 session->nr_max = 0xffff; 1695 else 1696 session->nr_max = 0xffffff; 1697 session->nr_window_size = session->nr_max / 2; 1698 session->nr_oos_count_max = 4; 1699 1700 /* Use NR of first received packet */ 1701 session->reorder_skip = 1; 1702 1703 sprintf(&session->name[0], "sess %u/%u", 1704 tunnel->tunnel_id, session->session_id); 1705 1706 skb_queue_head_init(&session->reorder_q); 1707 1708 INIT_HLIST_NODE(&session->hlist); 1709 INIT_HLIST_NODE(&session->global_hlist); 1710 1711 /* Inherit debug options from tunnel */ 1712 session->debug = tunnel->debug; 1713 1714 if (cfg) { 1715 session->pwtype = cfg->pw_type; 1716 session->debug = cfg->debug; 1717 session->mtu = cfg->mtu; 1718 session->mru = cfg->mru; 1719 session->send_seq = cfg->send_seq; 1720 session->recv_seq = cfg->recv_seq; 1721 session->lns_mode = cfg->lns_mode; 1722 session->reorder_timeout = cfg->reorder_timeout; 1723 session->l2specific_type = cfg->l2specific_type; 1724 session->cookie_len = cfg->cookie_len; 1725 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1726 session->peer_cookie_len = cfg->peer_cookie_len; 1727 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1728 } 1729 1730 if (tunnel->version == L2TP_HDR_VER_2) 1731 session->build_header = l2tp_build_l2tpv2_header; 1732 else 1733 session->build_header = l2tp_build_l2tpv3_header; 1734 1735 l2tp_session_set_header_len(session, tunnel->version); 1736 1737 refcount_set(&session->ref_count, 1); 1738 1739 return session; 1740 } 1741 1742 return ERR_PTR(-ENOMEM); 1743 } 1744 EXPORT_SYMBOL_GPL(l2tp_session_create); 1745 1746 /***************************************************************************** 1747 * Init and cleanup 1748 *****************************************************************************/ 1749 1750 static __net_init int l2tp_init_net(struct net *net) 1751 { 1752 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1753 int hash; 1754 1755 INIT_LIST_HEAD(&pn->l2tp_tunnel_list); 1756 spin_lock_init(&pn->l2tp_tunnel_list_lock); 1757 1758 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1759 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1760 1761 spin_lock_init(&pn->l2tp_session_hlist_lock); 1762 1763 return 0; 1764 } 1765 1766 static __net_exit void l2tp_exit_net(struct net *net) 1767 { 1768 struct l2tp_net *pn = l2tp_pernet(net); 1769 struct l2tp_tunnel *tunnel = NULL; 1770 int hash; 1771 1772 rcu_read_lock_bh(); 1773 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 1774 l2tp_tunnel_delete(tunnel); 1775 } 1776 rcu_read_unlock_bh(); 1777 1778 flush_workqueue(l2tp_wq); 1779 rcu_barrier(); 1780 1781 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1782 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); 1783 } 1784 1785 static struct pernet_operations l2tp_net_ops = { 1786 .init = l2tp_init_net, 1787 .exit = l2tp_exit_net, 1788 .id = &l2tp_net_id, 1789 .size = sizeof(struct l2tp_net), 1790 }; 1791 1792 static int __init l2tp_init(void) 1793 { 1794 int rc = 0; 1795 1796 rc = register_pernet_device(&l2tp_net_ops); 1797 if (rc) 1798 goto out; 1799 1800 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1801 if (!l2tp_wq) { 1802 pr_err("alloc_workqueue failed\n"); 1803 unregister_pernet_device(&l2tp_net_ops); 1804 rc = -ENOMEM; 1805 goto out; 1806 } 1807 1808 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 1809 1810 out: 1811 return rc; 1812 } 1813 1814 static void __exit l2tp_exit(void) 1815 { 1816 unregister_pernet_device(&l2tp_net_ops); 1817 if (l2tp_wq) { 1818 destroy_workqueue(l2tp_wq); 1819 l2tp_wq = NULL; 1820 } 1821 } 1822 1823 module_init(l2tp_init); 1824 module_exit(l2tp_exit); 1825 1826 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1827 MODULE_DESCRIPTION("L2TP core"); 1828 MODULE_LICENSE("GPL"); 1829 MODULE_VERSION(L2TP_DRV_VERSION); 1830 1831