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_MAX 14 87 88 /* Default trace flags */ 89 #define L2TP_DEFAULT_DEBUG_FLAGS 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 struct workqueue_struct *l2tp_wq; 103 104 /* per-net private data for this module */ 105 static unsigned int l2tp_net_id; 106 struct l2tp_net { 107 struct list_head l2tp_tunnel_list; 108 spinlock_t l2tp_tunnel_list_lock; 109 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; 110 spinlock_t l2tp_session_hlist_lock; 111 }; 112 113 #if IS_ENABLED(CONFIG_IPV6) 114 static bool l2tp_sk_is_v6(struct sock *sk) 115 { 116 return sk->sk_family == PF_INET6 && 117 !ipv6_addr_v4mapped(&sk->sk_v6_daddr); 118 } 119 #endif 120 121 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk) 122 { 123 return sk->sk_user_data; 124 } 125 126 static inline struct l2tp_net *l2tp_pernet(const struct net *net) 127 { 128 BUG_ON(!net); 129 130 return net_generic(net, l2tp_net_id); 131 } 132 133 /* Session hash global list for L2TPv3. 134 * The session_id SHOULD be random according to RFC3931, but several 135 * L2TP implementations use incrementing session_ids. So we do a real 136 * hash on the session_id, rather than a simple bitmask. 137 */ 138 static inline struct hlist_head * 139 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id) 140 { 141 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)]; 142 143 } 144 145 /* Session hash list. 146 * The session_id SHOULD be random according to RFC2661, but several 147 * L2TP implementations (Cisco and Microsoft) use incrementing 148 * session_ids. So we do a real hash on the session_id, rather than a 149 * simple bitmask. 150 */ 151 static inline struct hlist_head * 152 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id) 153 { 154 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)]; 155 } 156 157 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) 158 { 159 sock_put(tunnel->sock); 160 /* the tunnel is freed in the socket destructor */ 161 } 162 EXPORT_SYMBOL(l2tp_tunnel_free); 163 164 /* Lookup a tunnel. A new reference is held on the returned tunnel. */ 165 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) 166 { 167 const struct l2tp_net *pn = l2tp_pernet(net); 168 struct l2tp_tunnel *tunnel; 169 170 rcu_read_lock_bh(); 171 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 172 if (tunnel->tunnel_id == tunnel_id) { 173 l2tp_tunnel_inc_refcount(tunnel); 174 rcu_read_unlock_bh(); 175 176 return tunnel; 177 } 178 } 179 rcu_read_unlock_bh(); 180 181 return NULL; 182 } 183 EXPORT_SYMBOL_GPL(l2tp_tunnel_get); 184 185 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) 186 { 187 const struct l2tp_net *pn = l2tp_pernet(net); 188 struct l2tp_tunnel *tunnel; 189 int count = 0; 190 191 rcu_read_lock_bh(); 192 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 193 if (++count > nth) { 194 l2tp_tunnel_inc_refcount(tunnel); 195 rcu_read_unlock_bh(); 196 return tunnel; 197 } 198 } 199 rcu_read_unlock_bh(); 200 201 return NULL; 202 } 203 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth); 204 205 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel, 206 u32 session_id) 207 { 208 struct hlist_head *session_list; 209 struct l2tp_session *session; 210 211 session_list = l2tp_session_id_hash(tunnel, session_id); 212 213 read_lock_bh(&tunnel->hlist_lock); 214 hlist_for_each_entry(session, session_list, hlist) 215 if (session->session_id == session_id) { 216 l2tp_session_inc_refcount(session); 217 read_unlock_bh(&tunnel->hlist_lock); 218 219 return session; 220 } 221 read_unlock_bh(&tunnel->hlist_lock); 222 223 return NULL; 224 } 225 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_session); 226 227 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id) 228 { 229 struct hlist_head *session_list; 230 struct l2tp_session *session; 231 232 session_list = l2tp_session_id_hash_2(l2tp_pernet(net), session_id); 233 234 rcu_read_lock_bh(); 235 hlist_for_each_entry_rcu(session, session_list, global_hlist) 236 if (session->session_id == session_id) { 237 l2tp_session_inc_refcount(session); 238 rcu_read_unlock_bh(); 239 240 return session; 241 } 242 rcu_read_unlock_bh(); 243 244 return NULL; 245 } 246 EXPORT_SYMBOL_GPL(l2tp_session_get); 247 248 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth) 249 { 250 int hash; 251 struct l2tp_session *session; 252 int count = 0; 253 254 read_lock_bh(&tunnel->hlist_lock); 255 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 256 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) { 257 if (++count > nth) { 258 l2tp_session_inc_refcount(session); 259 read_unlock_bh(&tunnel->hlist_lock); 260 return session; 261 } 262 } 263 } 264 265 read_unlock_bh(&tunnel->hlist_lock); 266 267 return NULL; 268 } 269 EXPORT_SYMBOL_GPL(l2tp_session_get_nth); 270 271 /* Lookup a session by interface name. 272 * This is very inefficient but is only used by management interfaces. 273 */ 274 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 275 const char *ifname) 276 { 277 struct l2tp_net *pn = l2tp_pernet(net); 278 int hash; 279 struct l2tp_session *session; 280 281 rcu_read_lock_bh(); 282 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { 283 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) { 284 if (!strcmp(session->ifname, ifname)) { 285 l2tp_session_inc_refcount(session); 286 rcu_read_unlock_bh(); 287 288 return session; 289 } 290 } 291 } 292 293 rcu_read_unlock_bh(); 294 295 return NULL; 296 } 297 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); 298 299 int l2tp_session_register(struct l2tp_session *session, 300 struct l2tp_tunnel *tunnel) 301 { 302 struct l2tp_session *session_walk; 303 struct hlist_head *g_head; 304 struct hlist_head *head; 305 struct l2tp_net *pn; 306 int err; 307 308 head = l2tp_session_id_hash(tunnel, session->session_id); 309 310 write_lock_bh(&tunnel->hlist_lock); 311 if (!tunnel->acpt_newsess) { 312 err = -ENODEV; 313 goto err_tlock; 314 } 315 316 hlist_for_each_entry(session_walk, head, hlist) 317 if (session_walk->session_id == session->session_id) { 318 err = -EEXIST; 319 goto err_tlock; 320 } 321 322 if (tunnel->version == L2TP_HDR_VER_3) { 323 pn = l2tp_pernet(tunnel->l2tp_net); 324 g_head = l2tp_session_id_hash_2(pn, session->session_id); 325 326 spin_lock_bh(&pn->l2tp_session_hlist_lock); 327 328 hlist_for_each_entry(session_walk, g_head, global_hlist) 329 if (session_walk->session_id == session->session_id) { 330 err = -EEXIST; 331 goto err_tlock_pnlock; 332 } 333 334 l2tp_tunnel_inc_refcount(tunnel); 335 hlist_add_head_rcu(&session->global_hlist, g_head); 336 337 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 338 } else { 339 l2tp_tunnel_inc_refcount(tunnel); 340 } 341 342 hlist_add_head(&session->hlist, head); 343 write_unlock_bh(&tunnel->hlist_lock); 344 345 return 0; 346 347 err_tlock_pnlock: 348 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 349 err_tlock: 350 write_unlock_bh(&tunnel->hlist_lock); 351 352 return err; 353 } 354 EXPORT_SYMBOL_GPL(l2tp_session_register); 355 356 /***************************************************************************** 357 * Receive data handling 358 *****************************************************************************/ 359 360 /* Queue a skb in order. We come here only if the skb has an L2TP sequence 361 * number. 362 */ 363 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb) 364 { 365 struct sk_buff *skbp; 366 struct sk_buff *tmp; 367 u32 ns = L2TP_SKB_CB(skb)->ns; 368 369 spin_lock_bh(&session->reorder_q.lock); 370 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) { 371 if (L2TP_SKB_CB(skbp)->ns > ns) { 372 __skb_queue_before(&session->reorder_q, skbp, skb); 373 l2tp_dbg(session, L2TP_MSG_SEQ, 374 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n", 375 session->name, ns, L2TP_SKB_CB(skbp)->ns, 376 skb_queue_len(&session->reorder_q)); 377 atomic_long_inc(&session->stats.rx_oos_packets); 378 goto out; 379 } 380 } 381 382 __skb_queue_tail(&session->reorder_q, skb); 383 384 out: 385 spin_unlock_bh(&session->reorder_q.lock); 386 } 387 388 /* Dequeue a single skb. 389 */ 390 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb) 391 { 392 struct l2tp_tunnel *tunnel = session->tunnel; 393 int length = L2TP_SKB_CB(skb)->length; 394 395 /* We're about to requeue the skb, so return resources 396 * to its current owner (a socket receive buffer). 397 */ 398 skb_orphan(skb); 399 400 atomic_long_inc(&tunnel->stats.rx_packets); 401 atomic_long_add(length, &tunnel->stats.rx_bytes); 402 atomic_long_inc(&session->stats.rx_packets); 403 atomic_long_add(length, &session->stats.rx_bytes); 404 405 if (L2TP_SKB_CB(skb)->has_seq) { 406 /* Bump our Nr */ 407 session->nr++; 408 session->nr &= session->nr_max; 409 410 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n", 411 session->name, session->nr); 412 } 413 414 /* call private receive handler */ 415 if (session->recv_skb != NULL) 416 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); 417 else 418 kfree_skb(skb); 419 } 420 421 /* Dequeue skbs from the session's reorder_q, subject to packet order. 422 * Skbs that have been in the queue for too long are simply discarded. 423 */ 424 static void l2tp_recv_dequeue(struct l2tp_session *session) 425 { 426 struct sk_buff *skb; 427 struct sk_buff *tmp; 428 429 /* If the pkt at the head of the queue has the nr that we 430 * expect to send up next, dequeue it and any other 431 * in-sequence packets behind it. 432 */ 433 start: 434 spin_lock_bh(&session->reorder_q.lock); 435 skb_queue_walk_safe(&session->reorder_q, skb, tmp) { 436 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) { 437 atomic_long_inc(&session->stats.rx_seq_discards); 438 atomic_long_inc(&session->stats.rx_errors); 439 l2tp_dbg(session, L2TP_MSG_SEQ, 440 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n", 441 session->name, L2TP_SKB_CB(skb)->ns, 442 L2TP_SKB_CB(skb)->length, session->nr, 443 skb_queue_len(&session->reorder_q)); 444 session->reorder_skip = 1; 445 __skb_unlink(skb, &session->reorder_q); 446 kfree_skb(skb); 447 continue; 448 } 449 450 if (L2TP_SKB_CB(skb)->has_seq) { 451 if (session->reorder_skip) { 452 l2tp_dbg(session, L2TP_MSG_SEQ, 453 "%s: advancing nr to next pkt: %u -> %u", 454 session->name, session->nr, 455 L2TP_SKB_CB(skb)->ns); 456 session->reorder_skip = 0; 457 session->nr = L2TP_SKB_CB(skb)->ns; 458 } 459 if (L2TP_SKB_CB(skb)->ns != session->nr) { 460 l2tp_dbg(session, L2TP_MSG_SEQ, 461 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n", 462 session->name, L2TP_SKB_CB(skb)->ns, 463 L2TP_SKB_CB(skb)->length, session->nr, 464 skb_queue_len(&session->reorder_q)); 465 goto out; 466 } 467 } 468 __skb_unlink(skb, &session->reorder_q); 469 470 /* Process the skb. We release the queue lock while we 471 * do so to let other contexts process the queue. 472 */ 473 spin_unlock_bh(&session->reorder_q.lock); 474 l2tp_recv_dequeue_skb(session, skb); 475 goto start; 476 } 477 478 out: 479 spin_unlock_bh(&session->reorder_q.lock); 480 } 481 482 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr) 483 { 484 u32 nws; 485 486 if (nr >= session->nr) 487 nws = nr - session->nr; 488 else 489 nws = (session->nr_max + 1) - (session->nr - nr); 490 491 return nws < session->nr_window_size; 492 } 493 494 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if 495 * acceptable, else non-zero. 496 */ 497 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb) 498 { 499 if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) { 500 /* Packet sequence number is outside allowed window. 501 * Discard it. 502 */ 503 l2tp_dbg(session, L2TP_MSG_SEQ, 504 "%s: pkt %u len %d discarded, outside window, nr=%u\n", 505 session->name, L2TP_SKB_CB(skb)->ns, 506 L2TP_SKB_CB(skb)->length, session->nr); 507 goto discard; 508 } 509 510 if (session->reorder_timeout != 0) { 511 /* Packet reordering enabled. Add skb to session's 512 * reorder queue, in order of ns. 513 */ 514 l2tp_recv_queue_skb(session, skb); 515 goto out; 516 } 517 518 /* Packet reordering disabled. Discard out-of-sequence packets, while 519 * tracking the number if in-sequence packets after the first OOS packet 520 * is seen. After nr_oos_count_max in-sequence packets, reset the 521 * sequence number to re-enable packet reception. 522 */ 523 if (L2TP_SKB_CB(skb)->ns == session->nr) { 524 skb_queue_tail(&session->reorder_q, skb); 525 } else { 526 u32 nr_oos = L2TP_SKB_CB(skb)->ns; 527 u32 nr_next = (session->nr_oos + 1) & session->nr_max; 528 529 if (nr_oos == nr_next) 530 session->nr_oos_count++; 531 else 532 session->nr_oos_count = 0; 533 534 session->nr_oos = nr_oos; 535 if (session->nr_oos_count > session->nr_oos_count_max) { 536 session->reorder_skip = 1; 537 l2tp_dbg(session, L2TP_MSG_SEQ, 538 "%s: %d oos packets received. Resetting sequence numbers\n", 539 session->name, session->nr_oos_count); 540 } 541 if (!session->reorder_skip) { 542 atomic_long_inc(&session->stats.rx_seq_discards); 543 l2tp_dbg(session, L2TP_MSG_SEQ, 544 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n", 545 session->name, L2TP_SKB_CB(skb)->ns, 546 L2TP_SKB_CB(skb)->length, session->nr, 547 skb_queue_len(&session->reorder_q)); 548 goto discard; 549 } 550 skb_queue_tail(&session->reorder_q, skb); 551 } 552 553 out: 554 return 0; 555 556 discard: 557 return 1; 558 } 559 560 /* Do receive processing of L2TP data frames. We handle both L2TPv2 561 * and L2TPv3 data frames here. 562 * 563 * L2TPv2 Data Message Header 564 * 565 * 0 1 2 3 566 * 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 1 567 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 568 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) | 569 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 570 * | Tunnel ID | Session ID | 571 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 572 * | Ns (opt) | Nr (opt) | 573 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 574 * | Offset Size (opt) | Offset pad... (opt) 575 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 576 * 577 * Data frames are marked by T=0. All other fields are the same as 578 * those in L2TP control frames. 579 * 580 * L2TPv3 Data Message Header 581 * 582 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 583 * | L2TP Session Header | 584 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 585 * | L2-Specific Sublayer | 586 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 587 * | Tunnel Payload ... 588 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 589 * 590 * L2TPv3 Session Header Over IP 591 * 592 * 0 1 2 3 593 * 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 1 594 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 595 * | Session ID | 596 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 597 * | Cookie (optional, maximum 64 bits)... 598 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 599 * | 600 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 601 * 602 * L2TPv3 L2-Specific Sublayer Format 603 * 604 * 0 1 2 3 605 * 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 1 606 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 607 * |x|S|x|x|x|x|x|x| Sequence Number | 608 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 609 * 610 * Cookie value and sublayer format are negotiated with the peer when 611 * the session is set up. Unlike L2TPv2, we do not need to parse the 612 * packet header to determine if optional fields are present. 613 * 614 * Caller must already have parsed the frame and determined that it is 615 * a data (not control) frame before coming here. Fields up to the 616 * session-id have already been parsed and ptr points to the data 617 * after the session-id. 618 */ 619 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 620 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 621 int length) 622 { 623 struct l2tp_tunnel *tunnel = session->tunnel; 624 int offset; 625 u32 ns, nr; 626 627 /* Parse and check optional cookie */ 628 if (session->peer_cookie_len > 0) { 629 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { 630 l2tp_info(tunnel, L2TP_MSG_DATA, 631 "%s: cookie mismatch (%u/%u). Discarding.\n", 632 tunnel->name, tunnel->tunnel_id, 633 session->session_id); 634 atomic_long_inc(&session->stats.rx_cookie_discards); 635 goto discard; 636 } 637 ptr += session->peer_cookie_len; 638 } 639 640 /* Handle the optional sequence numbers. Sequence numbers are 641 * in different places for L2TPv2 and L2TPv3. 642 * 643 * If we are the LAC, enable/disable sequence numbers under 644 * the control of the LNS. If no sequence numbers present but 645 * we were expecting them, discard frame. 646 */ 647 ns = nr = 0; 648 L2TP_SKB_CB(skb)->has_seq = 0; 649 if (tunnel->version == L2TP_HDR_VER_2) { 650 if (hdrflags & L2TP_HDRFLAG_S) { 651 ns = ntohs(*(__be16 *) ptr); 652 ptr += 2; 653 nr = ntohs(*(__be16 *) ptr); 654 ptr += 2; 655 656 /* Store L2TP info in the skb */ 657 L2TP_SKB_CB(skb)->ns = ns; 658 L2TP_SKB_CB(skb)->has_seq = 1; 659 660 l2tp_dbg(session, L2TP_MSG_SEQ, 661 "%s: recv data ns=%u, nr=%u, session nr=%u\n", 662 session->name, ns, nr, session->nr); 663 } 664 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 665 u32 l2h = ntohl(*(__be32 *) ptr); 666 667 if (l2h & 0x40000000) { 668 ns = l2h & 0x00ffffff; 669 670 /* Store L2TP info in the skb */ 671 L2TP_SKB_CB(skb)->ns = ns; 672 L2TP_SKB_CB(skb)->has_seq = 1; 673 674 l2tp_dbg(session, L2TP_MSG_SEQ, 675 "%s: recv data ns=%u, session nr=%u\n", 676 session->name, ns, session->nr); 677 } 678 ptr += 4; 679 } 680 681 if (L2TP_SKB_CB(skb)->has_seq) { 682 /* Received a packet with sequence numbers. If we're the LNS, 683 * check if we sre sending sequence numbers and if not, 684 * configure it so. 685 */ 686 if ((!session->lns_mode) && (!session->send_seq)) { 687 l2tp_info(session, L2TP_MSG_SEQ, 688 "%s: requested to enable seq numbers by LNS\n", 689 session->name); 690 session->send_seq = 1; 691 l2tp_session_set_header_len(session, tunnel->version); 692 } 693 } else { 694 /* No sequence numbers. 695 * If user has configured mandatory sequence numbers, discard. 696 */ 697 if (session->recv_seq) { 698 l2tp_warn(session, L2TP_MSG_SEQ, 699 "%s: recv data has no seq numbers when required. Discarding.\n", 700 session->name); 701 atomic_long_inc(&session->stats.rx_seq_discards); 702 goto discard; 703 } 704 705 /* If we're the LAC and we're sending sequence numbers, the 706 * LNS has requested that we no longer send sequence numbers. 707 * If we're the LNS and we're sending sequence numbers, the 708 * LAC is broken. Discard the frame. 709 */ 710 if ((!session->lns_mode) && (session->send_seq)) { 711 l2tp_info(session, L2TP_MSG_SEQ, 712 "%s: requested to disable seq numbers by LNS\n", 713 session->name); 714 session->send_seq = 0; 715 l2tp_session_set_header_len(session, tunnel->version); 716 } else if (session->send_seq) { 717 l2tp_warn(session, L2TP_MSG_SEQ, 718 "%s: recv data has no seq numbers when required. Discarding.\n", 719 session->name); 720 atomic_long_inc(&session->stats.rx_seq_discards); 721 goto discard; 722 } 723 } 724 725 /* Session data offset is defined only for L2TPv2 and is 726 * indicated by an optional 16-bit value in the header. 727 */ 728 if (tunnel->version == L2TP_HDR_VER_2) { 729 /* If offset bit set, skip it. */ 730 if (hdrflags & L2TP_HDRFLAG_O) { 731 offset = ntohs(*(__be16 *)ptr); 732 ptr += 2 + offset; 733 } 734 } 735 736 offset = ptr - optr; 737 if (!pskb_may_pull(skb, offset)) 738 goto discard; 739 740 __skb_pull(skb, offset); 741 742 /* Prepare skb for adding to the session's reorder_q. Hold 743 * packets for max reorder_timeout or 1 second if not 744 * reordering. 745 */ 746 L2TP_SKB_CB(skb)->length = length; 747 L2TP_SKB_CB(skb)->expires = jiffies + 748 (session->reorder_timeout ? session->reorder_timeout : HZ); 749 750 /* Add packet to the session's receive queue. Reordering is done here, if 751 * enabled. Saved L2TP protocol info is stored in skb->sb[]. 752 */ 753 if (L2TP_SKB_CB(skb)->has_seq) { 754 if (l2tp_recv_data_seq(session, skb)) 755 goto discard; 756 } else { 757 /* No sequence numbers. Add the skb to the tail of the 758 * reorder queue. This ensures that it will be 759 * delivered after all previous sequenced skbs. 760 */ 761 skb_queue_tail(&session->reorder_q, skb); 762 } 763 764 /* Try to dequeue as many skbs from reorder_q as we can. */ 765 l2tp_recv_dequeue(session); 766 767 return; 768 769 discard: 770 atomic_long_inc(&session->stats.rx_errors); 771 kfree_skb(skb); 772 } 773 EXPORT_SYMBOL(l2tp_recv_common); 774 775 /* Drop skbs from the session's reorder_q 776 */ 777 static int l2tp_session_queue_purge(struct l2tp_session *session) 778 { 779 struct sk_buff *skb = NULL; 780 BUG_ON(!session); 781 BUG_ON(session->magic != L2TP_SESSION_MAGIC); 782 while ((skb = skb_dequeue(&session->reorder_q))) { 783 atomic_long_inc(&session->stats.rx_errors); 784 kfree_skb(skb); 785 } 786 return 0; 787 } 788 789 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame 790 * here. The skb is not on a list when we get here. 791 * Returns 0 if the packet was a data packet and was successfully passed on. 792 * Returns 1 if the packet was not a good data packet and could not be 793 * forwarded. All such packets are passed up to userspace to deal with. 794 */ 795 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb) 796 { 797 struct l2tp_session *session = NULL; 798 unsigned char *ptr, *optr; 799 u16 hdrflags; 800 u32 tunnel_id, session_id; 801 u16 version; 802 int length; 803 804 /* UDP has verifed checksum */ 805 806 /* UDP always verifies the packet length. */ 807 __skb_pull(skb, sizeof(struct udphdr)); 808 809 /* Short packet? */ 810 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX)) { 811 l2tp_info(tunnel, L2TP_MSG_DATA, 812 "%s: recv short packet (len=%d)\n", 813 tunnel->name, skb->len); 814 goto error; 815 } 816 817 /* Trace packet contents, if enabled */ 818 if (tunnel->debug & L2TP_MSG_DATA) { 819 length = min(32u, skb->len); 820 if (!pskb_may_pull(skb, length)) 821 goto error; 822 823 pr_debug("%s: recv\n", tunnel->name); 824 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 825 } 826 827 /* Point to L2TP header */ 828 optr = ptr = skb->data; 829 830 /* Get L2TP header flags */ 831 hdrflags = ntohs(*(__be16 *) ptr); 832 833 /* Check protocol version */ 834 version = hdrflags & L2TP_HDR_VER_MASK; 835 if (version != tunnel->version) { 836 l2tp_info(tunnel, L2TP_MSG_DATA, 837 "%s: recv protocol version mismatch: got %d expected %d\n", 838 tunnel->name, version, tunnel->version); 839 goto error; 840 } 841 842 /* Get length of L2TP packet */ 843 length = skb->len; 844 845 /* If type is control packet, it is handled by userspace. */ 846 if (hdrflags & L2TP_HDRFLAG_T) { 847 l2tp_dbg(tunnel, L2TP_MSG_DATA, 848 "%s: recv control packet, len=%d\n", 849 tunnel->name, length); 850 goto error; 851 } 852 853 /* Skip flags */ 854 ptr += 2; 855 856 if (tunnel->version == L2TP_HDR_VER_2) { 857 /* If length is present, skip it */ 858 if (hdrflags & L2TP_HDRFLAG_L) 859 ptr += 2; 860 861 /* Extract tunnel and session ID */ 862 tunnel_id = ntohs(*(__be16 *) ptr); 863 ptr += 2; 864 session_id = ntohs(*(__be16 *) ptr); 865 ptr += 2; 866 } else { 867 ptr += 2; /* skip reserved bits */ 868 tunnel_id = tunnel->tunnel_id; 869 session_id = ntohl(*(__be32 *) ptr); 870 ptr += 4; 871 } 872 873 /* Find the session context */ 874 session = l2tp_tunnel_get_session(tunnel, session_id); 875 if (!session || !session->recv_skb) { 876 if (session) 877 l2tp_session_dec_refcount(session); 878 879 /* Not found? Pass to userspace to deal with */ 880 l2tp_info(tunnel, L2TP_MSG_DATA, 881 "%s: no session found (%u/%u). Passing up.\n", 882 tunnel->name, tunnel_id, session_id); 883 goto error; 884 } 885 886 if (tunnel->version == L2TP_HDR_VER_3 && 887 l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) 888 goto error; 889 890 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length); 891 l2tp_session_dec_refcount(session); 892 893 return 0; 894 895 error: 896 /* Put UDP header back */ 897 __skb_push(skb, sizeof(struct udphdr)); 898 899 return 1; 900 } 901 902 /* UDP encapsulation receive handler. See net/ipv4/udp.c. 903 * Return codes: 904 * 0 : success. 905 * <0: error 906 * >0: skb should be passed up to userspace as UDP. 907 */ 908 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 909 { 910 struct l2tp_tunnel *tunnel; 911 912 tunnel = l2tp_tunnel(sk); 913 if (tunnel == NULL) 914 goto pass_up; 915 916 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n", 917 tunnel->name, skb->len); 918 919 if (l2tp_udp_recv_core(tunnel, skb)) 920 goto pass_up; 921 922 return 0; 923 924 pass_up: 925 return 1; 926 } 927 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 928 929 /************************************************************************ 930 * Transmit handling 931 ***********************************************************************/ 932 933 /* Build an L2TP header for the session into the buffer provided. 934 */ 935 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 936 { 937 struct l2tp_tunnel *tunnel = session->tunnel; 938 __be16 *bufp = buf; 939 __be16 *optr = buf; 940 u16 flags = L2TP_HDR_VER_2; 941 u32 tunnel_id = tunnel->peer_tunnel_id; 942 u32 session_id = session->peer_session_id; 943 944 if (session->send_seq) 945 flags |= L2TP_HDRFLAG_S; 946 947 /* Setup L2TP header. */ 948 *bufp++ = htons(flags); 949 *bufp++ = htons(tunnel_id); 950 *bufp++ = htons(session_id); 951 if (session->send_seq) { 952 *bufp++ = htons(session->ns); 953 *bufp++ = 0; 954 session->ns++; 955 session->ns &= 0xffff; 956 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n", 957 session->name, session->ns); 958 } 959 960 return bufp - optr; 961 } 962 963 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 964 { 965 struct l2tp_tunnel *tunnel = session->tunnel; 966 char *bufp = buf; 967 char *optr = bufp; 968 969 /* Setup L2TP header. The header differs slightly for UDP and 970 * IP encapsulations. For UDP, there is 4 bytes of flags. 971 */ 972 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 973 u16 flags = L2TP_HDR_VER_3; 974 *((__be16 *) bufp) = htons(flags); 975 bufp += 2; 976 *((__be16 *) bufp) = 0; 977 bufp += 2; 978 } 979 980 *((__be32 *) bufp) = htonl(session->peer_session_id); 981 bufp += 4; 982 if (session->cookie_len) { 983 memcpy(bufp, &session->cookie[0], session->cookie_len); 984 bufp += session->cookie_len; 985 } 986 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 987 u32 l2h = 0; 988 989 if (session->send_seq) { 990 l2h = 0x40000000 | session->ns; 991 session->ns++; 992 session->ns &= 0xffffff; 993 l2tp_dbg(session, L2TP_MSG_SEQ, 994 "%s: updated ns to %u\n", 995 session->name, session->ns); 996 } 997 998 *((__be32 *)bufp) = htonl(l2h); 999 bufp += 4; 1000 } 1001 1002 return bufp - optr; 1003 } 1004 1005 static void l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, 1006 struct flowi *fl, size_t data_len) 1007 { 1008 struct l2tp_tunnel *tunnel = session->tunnel; 1009 unsigned int len = skb->len; 1010 int error; 1011 1012 /* Debug */ 1013 if (session->send_seq) 1014 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes, ns=%u\n", 1015 session->name, data_len, session->ns - 1); 1016 else 1017 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes\n", 1018 session->name, data_len); 1019 1020 if (session->debug & L2TP_MSG_DATA) { 1021 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1022 unsigned char *datap = skb->data + uhlen; 1023 1024 pr_debug("%s: xmit\n", session->name); 1025 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, 1026 datap, min_t(size_t, 32, len - uhlen)); 1027 } 1028 1029 /* Queue the packet to IP for output */ 1030 skb->ignore_df = 1; 1031 #if IS_ENABLED(CONFIG_IPV6) 1032 if (l2tp_sk_is_v6(tunnel->sock)) 1033 error = inet6_csk_xmit(tunnel->sock, skb, NULL); 1034 else 1035 #endif 1036 error = ip_queue_xmit(tunnel->sock, skb, fl); 1037 1038 /* Update stats */ 1039 if (error >= 0) { 1040 atomic_long_inc(&tunnel->stats.tx_packets); 1041 atomic_long_add(len, &tunnel->stats.tx_bytes); 1042 atomic_long_inc(&session->stats.tx_packets); 1043 atomic_long_add(len, &session->stats.tx_bytes); 1044 } else { 1045 atomic_long_inc(&tunnel->stats.tx_errors); 1046 atomic_long_inc(&session->stats.tx_errors); 1047 } 1048 } 1049 1050 /* If caller requires the skb to have a ppp header, the header must be 1051 * inserted in the skb data before calling this function. 1052 */ 1053 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len) 1054 { 1055 int data_len = skb->len; 1056 struct l2tp_tunnel *tunnel = session->tunnel; 1057 struct sock *sk = tunnel->sock; 1058 struct flowi *fl; 1059 struct udphdr *uh; 1060 struct inet_sock *inet; 1061 int headroom; 1062 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1063 int udp_len; 1064 int ret = NET_XMIT_SUCCESS; 1065 1066 /* Check that there's enough headroom in the skb to insert IP, 1067 * UDP and L2TP headers. If not enough, expand it to 1068 * make room. Adjust truesize. 1069 */ 1070 headroom = NET_SKB_PAD + sizeof(struct iphdr) + 1071 uhlen + hdr_len; 1072 if (skb_cow_head(skb, headroom)) { 1073 kfree_skb(skb); 1074 return NET_XMIT_DROP; 1075 } 1076 1077 /* Setup L2TP header */ 1078 session->build_header(session, __skb_push(skb, hdr_len)); 1079 1080 /* Reset skb netfilter state */ 1081 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1082 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | 1083 IPSKB_REROUTED); 1084 nf_reset(skb); 1085 1086 bh_lock_sock(sk); 1087 if (sock_owned_by_user(sk)) { 1088 kfree_skb(skb); 1089 ret = NET_XMIT_DROP; 1090 goto out_unlock; 1091 } 1092 1093 /* The user-space may change the connection status for the user-space 1094 * provided socket at run time: we must check it under the socket lock 1095 */ 1096 if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) { 1097 kfree_skb(skb); 1098 ret = NET_XMIT_DROP; 1099 goto out_unlock; 1100 } 1101 1102 /* Get routing info from the tunnel socket */ 1103 skb_dst_drop(skb); 1104 skb_dst_set(skb, sk_dst_check(sk, 0)); 1105 1106 inet = inet_sk(sk); 1107 fl = &inet->cork.fl; 1108 switch (tunnel->encap) { 1109 case L2TP_ENCAPTYPE_UDP: 1110 /* Setup UDP header */ 1111 __skb_push(skb, sizeof(*uh)); 1112 skb_reset_transport_header(skb); 1113 uh = udp_hdr(skb); 1114 uh->source = inet->inet_sport; 1115 uh->dest = inet->inet_dport; 1116 udp_len = uhlen + hdr_len + data_len; 1117 uh->len = htons(udp_len); 1118 1119 /* Calculate UDP checksum if configured to do so */ 1120 #if IS_ENABLED(CONFIG_IPV6) 1121 if (l2tp_sk_is_v6(sk)) 1122 udp6_set_csum(udp_get_no_check6_tx(sk), 1123 skb, &inet6_sk(sk)->saddr, 1124 &sk->sk_v6_daddr, udp_len); 1125 else 1126 #endif 1127 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr, 1128 inet->inet_daddr, udp_len); 1129 break; 1130 1131 case L2TP_ENCAPTYPE_IP: 1132 break; 1133 } 1134 1135 l2tp_xmit_core(session, skb, fl, data_len); 1136 out_unlock: 1137 bh_unlock_sock(sk); 1138 1139 return ret; 1140 } 1141 EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1142 1143 /***************************************************************************** 1144 * Tinnel and session create/destroy. 1145 *****************************************************************************/ 1146 1147 /* Tunnel socket destruct hook. 1148 * The tunnel context is deleted only when all session sockets have been 1149 * closed. 1150 */ 1151 static void l2tp_tunnel_destruct(struct sock *sk) 1152 { 1153 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1154 1155 if (tunnel == NULL) 1156 goto end; 1157 1158 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name); 1159 1160 /* Disable udp encapsulation */ 1161 switch (tunnel->encap) { 1162 case L2TP_ENCAPTYPE_UDP: 1163 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1164 (udp_sk(sk))->encap_type = 0; 1165 (udp_sk(sk))->encap_rcv = NULL; 1166 (udp_sk(sk))->encap_destroy = NULL; 1167 break; 1168 case L2TP_ENCAPTYPE_IP: 1169 break; 1170 } 1171 1172 /* Remove hooks into tunnel socket */ 1173 sk->sk_destruct = tunnel->old_sk_destruct; 1174 sk->sk_user_data = NULL; 1175 1176 /* Call the original destructor */ 1177 if (sk->sk_destruct) 1178 (*sk->sk_destruct)(sk); 1179 1180 kfree_rcu(tunnel, rcu); 1181 end: 1182 return; 1183 } 1184 1185 /* When the tunnel is closed, all the attached sessions need to go too. 1186 */ 1187 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1188 { 1189 int hash; 1190 struct hlist_node *walk; 1191 struct hlist_node *tmp; 1192 struct l2tp_session *session; 1193 1194 BUG_ON(tunnel == NULL); 1195 1196 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n", 1197 tunnel->name); 1198 1199 write_lock_bh(&tunnel->hlist_lock); 1200 tunnel->acpt_newsess = false; 1201 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1202 again: 1203 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) { 1204 session = hlist_entry(walk, struct l2tp_session, hlist); 1205 1206 l2tp_info(session, L2TP_MSG_CONTROL, 1207 "%s: closing session\n", session->name); 1208 1209 hlist_del_init(&session->hlist); 1210 1211 if (test_and_set_bit(0, &session->dead)) 1212 goto again; 1213 1214 write_unlock_bh(&tunnel->hlist_lock); 1215 1216 __l2tp_session_unhash(session); 1217 l2tp_session_queue_purge(session); 1218 1219 if (session->session_close != NULL) 1220 (*session->session_close)(session); 1221 1222 l2tp_session_dec_refcount(session); 1223 1224 write_lock_bh(&tunnel->hlist_lock); 1225 1226 /* Now restart from the beginning of this hash 1227 * chain. We always remove a session from the 1228 * list so we are guaranteed to make forward 1229 * progress. 1230 */ 1231 goto again; 1232 } 1233 } 1234 write_unlock_bh(&tunnel->hlist_lock); 1235 } 1236 1237 /* Tunnel socket destroy hook for UDP encapsulation */ 1238 static void l2tp_udp_encap_destroy(struct sock *sk) 1239 { 1240 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1241 1242 if (tunnel) 1243 l2tp_tunnel_delete(tunnel); 1244 } 1245 1246 /* Workqueue tunnel deletion function */ 1247 static void l2tp_tunnel_del_work(struct work_struct *work) 1248 { 1249 struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, 1250 del_work); 1251 struct sock *sk = tunnel->sock; 1252 struct socket *sock = sk->sk_socket; 1253 struct l2tp_net *pn; 1254 1255 l2tp_tunnel_closeall(tunnel); 1256 1257 /* If the tunnel socket was created within the kernel, use 1258 * the sk API to release it here. 1259 */ 1260 if (tunnel->fd < 0) { 1261 if (sock) { 1262 kernel_sock_shutdown(sock, SHUT_RDWR); 1263 sock_release(sock); 1264 } 1265 } 1266 1267 /* Remove the tunnel struct from the tunnel list */ 1268 pn = l2tp_pernet(tunnel->l2tp_net); 1269 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1270 list_del_rcu(&tunnel->list); 1271 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1272 1273 /* drop initial ref */ 1274 l2tp_tunnel_dec_refcount(tunnel); 1275 1276 /* drop workqueue ref */ 1277 l2tp_tunnel_dec_refcount(tunnel); 1278 } 1279 1280 /* Create a socket for the tunnel, if one isn't set up by 1281 * userspace. This is used for static tunnels where there is no 1282 * managing L2TP daemon. 1283 * 1284 * Since we don't want these sockets to keep a namespace alive by 1285 * themselves, we drop the socket's namespace refcount after creation. 1286 * These sockets are freed when the namespace exits using the pernet 1287 * exit hook. 1288 */ 1289 static int l2tp_tunnel_sock_create(struct net *net, 1290 u32 tunnel_id, 1291 u32 peer_tunnel_id, 1292 struct l2tp_tunnel_cfg *cfg, 1293 struct socket **sockp) 1294 { 1295 int err = -EINVAL; 1296 struct socket *sock = NULL; 1297 struct udp_port_cfg udp_conf; 1298 1299 switch (cfg->encap) { 1300 case L2TP_ENCAPTYPE_UDP: 1301 memset(&udp_conf, 0, sizeof(udp_conf)); 1302 1303 #if IS_ENABLED(CONFIG_IPV6) 1304 if (cfg->local_ip6 && cfg->peer_ip6) { 1305 udp_conf.family = AF_INET6; 1306 memcpy(&udp_conf.local_ip6, cfg->local_ip6, 1307 sizeof(udp_conf.local_ip6)); 1308 memcpy(&udp_conf.peer_ip6, cfg->peer_ip6, 1309 sizeof(udp_conf.peer_ip6)); 1310 udp_conf.use_udp6_tx_checksums = 1311 ! cfg->udp6_zero_tx_checksums; 1312 udp_conf.use_udp6_rx_checksums = 1313 ! cfg->udp6_zero_rx_checksums; 1314 } else 1315 #endif 1316 { 1317 udp_conf.family = AF_INET; 1318 udp_conf.local_ip = cfg->local_ip; 1319 udp_conf.peer_ip = cfg->peer_ip; 1320 udp_conf.use_udp_checksums = cfg->use_udp_checksums; 1321 } 1322 1323 udp_conf.local_udp_port = htons(cfg->local_udp_port); 1324 udp_conf.peer_udp_port = htons(cfg->peer_udp_port); 1325 1326 err = udp_sock_create(net, &udp_conf, &sock); 1327 if (err < 0) 1328 goto out; 1329 1330 break; 1331 1332 case L2TP_ENCAPTYPE_IP: 1333 #if IS_ENABLED(CONFIG_IPV6) 1334 if (cfg->local_ip6 && cfg->peer_ip6) { 1335 struct sockaddr_l2tpip6 ip6_addr = {0}; 1336 1337 err = sock_create_kern(net, AF_INET6, SOCK_DGRAM, 1338 IPPROTO_L2TP, &sock); 1339 if (err < 0) 1340 goto out; 1341 1342 ip6_addr.l2tp_family = AF_INET6; 1343 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6, 1344 sizeof(ip6_addr.l2tp_addr)); 1345 ip6_addr.l2tp_conn_id = tunnel_id; 1346 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr, 1347 sizeof(ip6_addr)); 1348 if (err < 0) 1349 goto out; 1350 1351 ip6_addr.l2tp_family = AF_INET6; 1352 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6, 1353 sizeof(ip6_addr.l2tp_addr)); 1354 ip6_addr.l2tp_conn_id = peer_tunnel_id; 1355 err = kernel_connect(sock, 1356 (struct sockaddr *) &ip6_addr, 1357 sizeof(ip6_addr), 0); 1358 if (err < 0) 1359 goto out; 1360 } else 1361 #endif 1362 { 1363 struct sockaddr_l2tpip ip_addr = {0}; 1364 1365 err = sock_create_kern(net, AF_INET, SOCK_DGRAM, 1366 IPPROTO_L2TP, &sock); 1367 if (err < 0) 1368 goto out; 1369 1370 ip_addr.l2tp_family = AF_INET; 1371 ip_addr.l2tp_addr = cfg->local_ip; 1372 ip_addr.l2tp_conn_id = tunnel_id; 1373 err = kernel_bind(sock, (struct sockaddr *) &ip_addr, 1374 sizeof(ip_addr)); 1375 if (err < 0) 1376 goto out; 1377 1378 ip_addr.l2tp_family = AF_INET; 1379 ip_addr.l2tp_addr = cfg->peer_ip; 1380 ip_addr.l2tp_conn_id = peer_tunnel_id; 1381 err = kernel_connect(sock, (struct sockaddr *) &ip_addr, 1382 sizeof(ip_addr), 0); 1383 if (err < 0) 1384 goto out; 1385 } 1386 break; 1387 1388 default: 1389 goto out; 1390 } 1391 1392 out: 1393 *sockp = sock; 1394 if ((err < 0) && sock) { 1395 kernel_sock_shutdown(sock, SHUT_RDWR); 1396 sock_release(sock); 1397 *sockp = NULL; 1398 } 1399 1400 return err; 1401 } 1402 1403 static struct lock_class_key l2tp_socket_class; 1404 1405 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) 1406 { 1407 struct l2tp_tunnel *tunnel = NULL; 1408 int err; 1409 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1410 1411 if (cfg != NULL) 1412 encap = cfg->encap; 1413 1414 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL); 1415 if (tunnel == NULL) { 1416 err = -ENOMEM; 1417 goto err; 1418 } 1419 1420 tunnel->version = version; 1421 tunnel->tunnel_id = tunnel_id; 1422 tunnel->peer_tunnel_id = peer_tunnel_id; 1423 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS; 1424 1425 tunnel->magic = L2TP_TUNNEL_MAGIC; 1426 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1427 rwlock_init(&tunnel->hlist_lock); 1428 tunnel->acpt_newsess = true; 1429 1430 if (cfg != NULL) 1431 tunnel->debug = cfg->debug; 1432 1433 tunnel->encap = encap; 1434 1435 refcount_set(&tunnel->ref_count, 1); 1436 tunnel->fd = fd; 1437 1438 /* Init delete workqueue struct */ 1439 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); 1440 1441 INIT_LIST_HEAD(&tunnel->list); 1442 1443 err = 0; 1444 err: 1445 if (tunnelp) 1446 *tunnelp = tunnel; 1447 1448 return err; 1449 } 1450 EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1451 1452 static int l2tp_validate_socket(const struct sock *sk, const struct net *net, 1453 enum l2tp_encap_type encap) 1454 { 1455 if (!net_eq(sock_net(sk), net)) 1456 return -EINVAL; 1457 1458 if (sk->sk_type != SOCK_DGRAM) 1459 return -EPROTONOSUPPORT; 1460 1461 if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) || 1462 (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP)) 1463 return -EPROTONOSUPPORT; 1464 1465 if (sk->sk_user_data) 1466 return -EBUSY; 1467 1468 return 0; 1469 } 1470 1471 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 1472 struct l2tp_tunnel_cfg *cfg) 1473 { 1474 struct l2tp_tunnel *tunnel_walk; 1475 struct l2tp_net *pn; 1476 struct socket *sock; 1477 struct sock *sk; 1478 int ret; 1479 1480 if (tunnel->fd < 0) { 1481 ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id, 1482 tunnel->peer_tunnel_id, cfg, 1483 &sock); 1484 if (ret < 0) 1485 goto err; 1486 } else { 1487 sock = sockfd_lookup(tunnel->fd, &ret); 1488 if (!sock) 1489 goto err; 1490 1491 ret = l2tp_validate_socket(sock->sk, net, tunnel->encap); 1492 if (ret < 0) 1493 goto err_sock; 1494 } 1495 1496 tunnel->l2tp_net = net; 1497 pn = l2tp_pernet(net); 1498 1499 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1500 list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) { 1501 if (tunnel_walk->tunnel_id == tunnel->tunnel_id) { 1502 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1503 1504 ret = -EEXIST; 1505 goto err_sock; 1506 } 1507 } 1508 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); 1509 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1510 1511 sk = sock->sk; 1512 sock_hold(sk); 1513 tunnel->sock = sk; 1514 1515 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1516 struct udp_tunnel_sock_cfg udp_cfg = { 1517 .sk_user_data = tunnel, 1518 .encap_type = UDP_ENCAP_L2TPINUDP, 1519 .encap_rcv = l2tp_udp_encap_recv, 1520 .encap_destroy = l2tp_udp_encap_destroy, 1521 }; 1522 1523 setup_udp_tunnel_sock(net, sock, &udp_cfg); 1524 } else { 1525 sk->sk_user_data = tunnel; 1526 } 1527 1528 tunnel->old_sk_destruct = sk->sk_destruct; 1529 sk->sk_destruct = &l2tp_tunnel_destruct; 1530 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, 1531 "l2tp_sock"); 1532 sk->sk_allocation = GFP_ATOMIC; 1533 1534 if (tunnel->fd >= 0) 1535 sockfd_put(sock); 1536 1537 return 0; 1538 1539 err_sock: 1540 if (tunnel->fd < 0) 1541 sock_release(sock); 1542 else 1543 sockfd_put(sock); 1544 err: 1545 return ret; 1546 } 1547 EXPORT_SYMBOL_GPL(l2tp_tunnel_register); 1548 1549 /* This function is used by the netlink TUNNEL_DELETE command. 1550 */ 1551 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1552 { 1553 if (!test_and_set_bit(0, &tunnel->dead)) { 1554 l2tp_tunnel_inc_refcount(tunnel); 1555 queue_work(l2tp_wq, &tunnel->del_work); 1556 } 1557 } 1558 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1559 1560 /* Really kill the session. 1561 */ 1562 void l2tp_session_free(struct l2tp_session *session) 1563 { 1564 struct l2tp_tunnel *tunnel = session->tunnel; 1565 1566 BUG_ON(refcount_read(&session->ref_count) != 0); 1567 1568 if (tunnel) { 1569 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC); 1570 l2tp_tunnel_dec_refcount(tunnel); 1571 } 1572 1573 kfree(session); 1574 } 1575 EXPORT_SYMBOL_GPL(l2tp_session_free); 1576 1577 /* Remove an l2tp session from l2tp_core's hash lists. 1578 * Provides a tidyup interface for pseudowire code which can't just route all 1579 * shutdown via. l2tp_session_delete and a pseudowire-specific session_close 1580 * callback. 1581 */ 1582 void __l2tp_session_unhash(struct l2tp_session *session) 1583 { 1584 struct l2tp_tunnel *tunnel = session->tunnel; 1585 1586 /* Remove the session from core hashes */ 1587 if (tunnel) { 1588 /* Remove from the per-tunnel hash */ 1589 write_lock_bh(&tunnel->hlist_lock); 1590 hlist_del_init(&session->hlist); 1591 write_unlock_bh(&tunnel->hlist_lock); 1592 1593 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1594 if (tunnel->version != L2TP_HDR_VER_2) { 1595 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1596 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1597 hlist_del_init_rcu(&session->global_hlist); 1598 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1599 synchronize_rcu(); 1600 } 1601 } 1602 } 1603 EXPORT_SYMBOL_GPL(__l2tp_session_unhash); 1604 1605 /* This function is used by the netlink SESSION_DELETE command and by 1606 pseudowire modules. 1607 */ 1608 int l2tp_session_delete(struct l2tp_session *session) 1609 { 1610 if (test_and_set_bit(0, &session->dead)) 1611 return 0; 1612 1613 __l2tp_session_unhash(session); 1614 l2tp_session_queue_purge(session); 1615 if (session->session_close != NULL) 1616 (*session->session_close)(session); 1617 1618 l2tp_session_dec_refcount(session); 1619 1620 return 0; 1621 } 1622 EXPORT_SYMBOL_GPL(l2tp_session_delete); 1623 1624 /* We come here whenever a session's send_seq, cookie_len or 1625 * l2specific_type parameters are set. 1626 */ 1627 void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1628 { 1629 if (version == L2TP_HDR_VER_2) { 1630 session->hdr_len = 6; 1631 if (session->send_seq) 1632 session->hdr_len += 4; 1633 } else { 1634 session->hdr_len = 4 + session->cookie_len; 1635 session->hdr_len += l2tp_get_l2specific_len(session); 1636 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1637 session->hdr_len += 4; 1638 } 1639 1640 } 1641 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1642 1643 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) 1644 { 1645 struct l2tp_session *session; 1646 1647 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL); 1648 if (session != NULL) { 1649 session->magic = L2TP_SESSION_MAGIC; 1650 session->tunnel = tunnel; 1651 1652 session->session_id = session_id; 1653 session->peer_session_id = peer_session_id; 1654 session->nr = 0; 1655 if (tunnel->version == L2TP_HDR_VER_2) 1656 session->nr_max = 0xffff; 1657 else 1658 session->nr_max = 0xffffff; 1659 session->nr_window_size = session->nr_max / 2; 1660 session->nr_oos_count_max = 4; 1661 1662 /* Use NR of first received packet */ 1663 session->reorder_skip = 1; 1664 1665 sprintf(&session->name[0], "sess %u/%u", 1666 tunnel->tunnel_id, session->session_id); 1667 1668 skb_queue_head_init(&session->reorder_q); 1669 1670 INIT_HLIST_NODE(&session->hlist); 1671 INIT_HLIST_NODE(&session->global_hlist); 1672 1673 /* Inherit debug options from tunnel */ 1674 session->debug = tunnel->debug; 1675 1676 if (cfg) { 1677 session->pwtype = cfg->pw_type; 1678 session->debug = cfg->debug; 1679 session->send_seq = cfg->send_seq; 1680 session->recv_seq = cfg->recv_seq; 1681 session->lns_mode = cfg->lns_mode; 1682 session->reorder_timeout = cfg->reorder_timeout; 1683 session->l2specific_type = cfg->l2specific_type; 1684 session->cookie_len = cfg->cookie_len; 1685 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1686 session->peer_cookie_len = cfg->peer_cookie_len; 1687 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1688 } 1689 1690 if (tunnel->version == L2TP_HDR_VER_2) 1691 session->build_header = l2tp_build_l2tpv2_header; 1692 else 1693 session->build_header = l2tp_build_l2tpv3_header; 1694 1695 l2tp_session_set_header_len(session, tunnel->version); 1696 1697 refcount_set(&session->ref_count, 1); 1698 1699 return session; 1700 } 1701 1702 return ERR_PTR(-ENOMEM); 1703 } 1704 EXPORT_SYMBOL_GPL(l2tp_session_create); 1705 1706 /***************************************************************************** 1707 * Init and cleanup 1708 *****************************************************************************/ 1709 1710 static __net_init int l2tp_init_net(struct net *net) 1711 { 1712 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1713 int hash; 1714 1715 INIT_LIST_HEAD(&pn->l2tp_tunnel_list); 1716 spin_lock_init(&pn->l2tp_tunnel_list_lock); 1717 1718 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1719 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1720 1721 spin_lock_init(&pn->l2tp_session_hlist_lock); 1722 1723 return 0; 1724 } 1725 1726 static __net_exit void l2tp_exit_net(struct net *net) 1727 { 1728 struct l2tp_net *pn = l2tp_pernet(net); 1729 struct l2tp_tunnel *tunnel = NULL; 1730 int hash; 1731 1732 rcu_read_lock_bh(); 1733 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 1734 l2tp_tunnel_delete(tunnel); 1735 } 1736 rcu_read_unlock_bh(); 1737 1738 flush_workqueue(l2tp_wq); 1739 rcu_barrier(); 1740 1741 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1742 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); 1743 } 1744 1745 static struct pernet_operations l2tp_net_ops = { 1746 .init = l2tp_init_net, 1747 .exit = l2tp_exit_net, 1748 .id = &l2tp_net_id, 1749 .size = sizeof(struct l2tp_net), 1750 }; 1751 1752 static int __init l2tp_init(void) 1753 { 1754 int rc = 0; 1755 1756 rc = register_pernet_device(&l2tp_net_ops); 1757 if (rc) 1758 goto out; 1759 1760 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1761 if (!l2tp_wq) { 1762 pr_err("alloc_workqueue failed\n"); 1763 unregister_pernet_device(&l2tp_net_ops); 1764 rc = -ENOMEM; 1765 goto out; 1766 } 1767 1768 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 1769 1770 out: 1771 return rc; 1772 } 1773 1774 static void __exit l2tp_exit(void) 1775 { 1776 unregister_pernet_device(&l2tp_net_ops); 1777 if (l2tp_wq) { 1778 destroy_workqueue(l2tp_wq); 1779 l2tp_wq = NULL; 1780 } 1781 } 1782 1783 module_init(l2tp_init); 1784 module_exit(l2tp_exit); 1785 1786 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1787 MODULE_DESCRIPTION("L2TP core"); 1788 MODULE_LICENSE("GPL"); 1789 MODULE_VERSION(L2TP_DRV_VERSION); 1790