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 #if IS_ENABLED(CONFIG_IPV6) 115 static bool l2tp_sk_is_v6(struct sock *sk) 116 { 117 return sk->sk_family == PF_INET6 && 118 !ipv6_addr_v4mapped(&sk->sk_v6_daddr); 119 } 120 #endif 121 122 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk) 123 { 124 return sk->sk_user_data; 125 } 126 127 static inline struct l2tp_net *l2tp_pernet(const struct net *net) 128 { 129 BUG_ON(!net); 130 131 return net_generic(net, l2tp_net_id); 132 } 133 134 /* Session hash global list for L2TPv3. 135 * The session_id SHOULD be random according to RFC3931, but several 136 * L2TP implementations use incrementing session_ids. So we do a real 137 * hash on the session_id, rather than a simple bitmask. 138 */ 139 static inline struct hlist_head * 140 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id) 141 { 142 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)]; 143 144 } 145 146 /* Session hash list. 147 * The session_id SHOULD be random according to RFC2661, but several 148 * L2TP implementations (Cisco and Microsoft) use incrementing 149 * session_ids. So we do a real hash on the session_id, rather than a 150 * simple bitmask. 151 */ 152 static inline struct hlist_head * 153 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id) 154 { 155 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)]; 156 } 157 158 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) 159 { 160 sock_put(tunnel->sock); 161 /* the tunnel is freed in the socket destructor */ 162 } 163 EXPORT_SYMBOL(l2tp_tunnel_free); 164 165 /* Lookup a tunnel. A new reference is held on the returned tunnel. */ 166 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) 167 { 168 const struct l2tp_net *pn = l2tp_pernet(net); 169 struct l2tp_tunnel *tunnel; 170 171 rcu_read_lock_bh(); 172 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 173 if (tunnel->tunnel_id == tunnel_id) { 174 l2tp_tunnel_inc_refcount(tunnel); 175 rcu_read_unlock_bh(); 176 177 return tunnel; 178 } 179 } 180 rcu_read_unlock_bh(); 181 182 return NULL; 183 } 184 EXPORT_SYMBOL_GPL(l2tp_tunnel_get); 185 186 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) 187 { 188 const struct l2tp_net *pn = l2tp_pernet(net); 189 struct l2tp_tunnel *tunnel; 190 int count = 0; 191 192 rcu_read_lock_bh(); 193 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 194 if (++count > nth) { 195 l2tp_tunnel_inc_refcount(tunnel); 196 rcu_read_unlock_bh(); 197 return tunnel; 198 } 199 } 200 rcu_read_unlock_bh(); 201 202 return NULL; 203 } 204 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth); 205 206 /* Lookup a session. A new reference is held on the returned session. */ 207 struct l2tp_session *l2tp_session_get(const struct net *net, 208 struct l2tp_tunnel *tunnel, 209 u32 session_id) 210 { 211 struct hlist_head *session_list; 212 struct l2tp_session *session; 213 214 if (!tunnel) { 215 struct l2tp_net *pn = l2tp_pernet(net); 216 217 session_list = l2tp_session_id_hash_2(pn, session_id); 218 219 rcu_read_lock_bh(); 220 hlist_for_each_entry_rcu(session, session_list, global_hlist) { 221 if (session->session_id == session_id) { 222 l2tp_session_inc_refcount(session); 223 rcu_read_unlock_bh(); 224 225 return session; 226 } 227 } 228 rcu_read_unlock_bh(); 229 230 return NULL; 231 } 232 233 session_list = l2tp_session_id_hash(tunnel, session_id); 234 read_lock_bh(&tunnel->hlist_lock); 235 hlist_for_each_entry(session, session_list, hlist) { 236 if (session->session_id == session_id) { 237 l2tp_session_inc_refcount(session); 238 read_unlock_bh(&tunnel->hlist_lock); 239 240 return session; 241 } 242 } 243 read_unlock_bh(&tunnel->hlist_lock); 244 245 return NULL; 246 } 247 EXPORT_SYMBOL_GPL(l2tp_session_get); 248 249 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth) 250 { 251 int hash; 252 struct l2tp_session *session; 253 int count = 0; 254 255 read_lock_bh(&tunnel->hlist_lock); 256 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 257 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) { 258 if (++count > nth) { 259 l2tp_session_inc_refcount(session); 260 read_unlock_bh(&tunnel->hlist_lock); 261 return session; 262 } 263 } 264 } 265 266 read_unlock_bh(&tunnel->hlist_lock); 267 268 return NULL; 269 } 270 EXPORT_SYMBOL_GPL(l2tp_session_get_nth); 271 272 /* Lookup a session by interface name. 273 * This is very inefficient but is only used by management interfaces. 274 */ 275 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 276 const char *ifname) 277 { 278 struct l2tp_net *pn = l2tp_pernet(net); 279 int hash; 280 struct l2tp_session *session; 281 282 rcu_read_lock_bh(); 283 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { 284 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) { 285 if (!strcmp(session->ifname, ifname)) { 286 l2tp_session_inc_refcount(session); 287 rcu_read_unlock_bh(); 288 289 return session; 290 } 291 } 292 } 293 294 rcu_read_unlock_bh(); 295 296 return NULL; 297 } 298 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); 299 300 int l2tp_session_register(struct l2tp_session *session, 301 struct l2tp_tunnel *tunnel) 302 { 303 struct l2tp_session *session_walk; 304 struct hlist_head *g_head; 305 struct hlist_head *head; 306 struct l2tp_net *pn; 307 int err; 308 309 head = l2tp_session_id_hash(tunnel, session->session_id); 310 311 write_lock_bh(&tunnel->hlist_lock); 312 if (!tunnel->acpt_newsess) { 313 err = -ENODEV; 314 goto err_tlock; 315 } 316 317 hlist_for_each_entry(session_walk, head, hlist) 318 if (session_walk->session_id == session->session_id) { 319 err = -EEXIST; 320 goto err_tlock; 321 } 322 323 if (tunnel->version == L2TP_HDR_VER_3) { 324 pn = l2tp_pernet(tunnel->l2tp_net); 325 g_head = l2tp_session_id_hash_2(pn, session->session_id); 326 327 spin_lock_bh(&pn->l2tp_session_hlist_lock); 328 329 hlist_for_each_entry(session_walk, g_head, global_hlist) 330 if (session_walk->session_id == session->session_id) { 331 err = -EEXIST; 332 goto err_tlock_pnlock; 333 } 334 335 l2tp_tunnel_inc_refcount(tunnel); 336 hlist_add_head_rcu(&session->global_hlist, g_head); 337 338 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 339 } else { 340 l2tp_tunnel_inc_refcount(tunnel); 341 } 342 343 hlist_add_head(&session->hlist, head); 344 write_unlock_bh(&tunnel->hlist_lock); 345 346 return 0; 347 348 err_tlock_pnlock: 349 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 350 err_tlock: 351 write_unlock_bh(&tunnel->hlist_lock); 352 353 return err; 354 } 355 EXPORT_SYMBOL_GPL(l2tp_session_register); 356 357 /***************************************************************************** 358 * Receive data handling 359 *****************************************************************************/ 360 361 /* Queue a skb in order. We come here only if the skb has an L2TP sequence 362 * number. 363 */ 364 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb) 365 { 366 struct sk_buff *skbp; 367 struct sk_buff *tmp; 368 u32 ns = L2TP_SKB_CB(skb)->ns; 369 370 spin_lock_bh(&session->reorder_q.lock); 371 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) { 372 if (L2TP_SKB_CB(skbp)->ns > ns) { 373 __skb_queue_before(&session->reorder_q, skbp, skb); 374 l2tp_dbg(session, L2TP_MSG_SEQ, 375 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n", 376 session->name, ns, L2TP_SKB_CB(skbp)->ns, 377 skb_queue_len(&session->reorder_q)); 378 atomic_long_inc(&session->stats.rx_oos_packets); 379 goto out; 380 } 381 } 382 383 __skb_queue_tail(&session->reorder_q, skb); 384 385 out: 386 spin_unlock_bh(&session->reorder_q.lock); 387 } 388 389 /* Dequeue a single skb. 390 */ 391 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb) 392 { 393 struct l2tp_tunnel *tunnel = session->tunnel; 394 int length = L2TP_SKB_CB(skb)->length; 395 396 /* We're about to requeue the skb, so return resources 397 * to its current owner (a socket receive buffer). 398 */ 399 skb_orphan(skb); 400 401 atomic_long_inc(&tunnel->stats.rx_packets); 402 atomic_long_add(length, &tunnel->stats.rx_bytes); 403 atomic_long_inc(&session->stats.rx_packets); 404 atomic_long_add(length, &session->stats.rx_bytes); 405 406 if (L2TP_SKB_CB(skb)->has_seq) { 407 /* Bump our Nr */ 408 session->nr++; 409 session->nr &= session->nr_max; 410 411 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n", 412 session->name, session->nr); 413 } 414 415 /* call private receive handler */ 416 if (session->recv_skb != NULL) 417 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); 418 else 419 kfree_skb(skb); 420 } 421 422 /* Dequeue skbs from the session's reorder_q, subject to packet order. 423 * Skbs that have been in the queue for too long are simply discarded. 424 */ 425 static void l2tp_recv_dequeue(struct l2tp_session *session) 426 { 427 struct sk_buff *skb; 428 struct sk_buff *tmp; 429 430 /* If the pkt at the head of the queue has the nr that we 431 * expect to send up next, dequeue it and any other 432 * in-sequence packets behind it. 433 */ 434 start: 435 spin_lock_bh(&session->reorder_q.lock); 436 skb_queue_walk_safe(&session->reorder_q, skb, tmp) { 437 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) { 438 atomic_long_inc(&session->stats.rx_seq_discards); 439 atomic_long_inc(&session->stats.rx_errors); 440 l2tp_dbg(session, L2TP_MSG_SEQ, 441 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n", 442 session->name, L2TP_SKB_CB(skb)->ns, 443 L2TP_SKB_CB(skb)->length, session->nr, 444 skb_queue_len(&session->reorder_q)); 445 session->reorder_skip = 1; 446 __skb_unlink(skb, &session->reorder_q); 447 kfree_skb(skb); 448 continue; 449 } 450 451 if (L2TP_SKB_CB(skb)->has_seq) { 452 if (session->reorder_skip) { 453 l2tp_dbg(session, L2TP_MSG_SEQ, 454 "%s: advancing nr to next pkt: %u -> %u", 455 session->name, session->nr, 456 L2TP_SKB_CB(skb)->ns); 457 session->reorder_skip = 0; 458 session->nr = L2TP_SKB_CB(skb)->ns; 459 } 460 if (L2TP_SKB_CB(skb)->ns != session->nr) { 461 l2tp_dbg(session, L2TP_MSG_SEQ, 462 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n", 463 session->name, L2TP_SKB_CB(skb)->ns, 464 L2TP_SKB_CB(skb)->length, session->nr, 465 skb_queue_len(&session->reorder_q)); 466 goto out; 467 } 468 } 469 __skb_unlink(skb, &session->reorder_q); 470 471 /* Process the skb. We release the queue lock while we 472 * do so to let other contexts process the queue. 473 */ 474 spin_unlock_bh(&session->reorder_q.lock); 475 l2tp_recv_dequeue_skb(session, skb); 476 goto start; 477 } 478 479 out: 480 spin_unlock_bh(&session->reorder_q.lock); 481 } 482 483 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr) 484 { 485 u32 nws; 486 487 if (nr >= session->nr) 488 nws = nr - session->nr; 489 else 490 nws = (session->nr_max + 1) - (session->nr - nr); 491 492 return nws < session->nr_window_size; 493 } 494 495 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if 496 * acceptable, else non-zero. 497 */ 498 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb) 499 { 500 if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) { 501 /* Packet sequence number is outside allowed window. 502 * Discard it. 503 */ 504 l2tp_dbg(session, L2TP_MSG_SEQ, 505 "%s: pkt %u len %d discarded, outside window, nr=%u\n", 506 session->name, L2TP_SKB_CB(skb)->ns, 507 L2TP_SKB_CB(skb)->length, session->nr); 508 goto discard; 509 } 510 511 if (session->reorder_timeout != 0) { 512 /* Packet reordering enabled. Add skb to session's 513 * reorder queue, in order of ns. 514 */ 515 l2tp_recv_queue_skb(session, skb); 516 goto out; 517 } 518 519 /* Packet reordering disabled. Discard out-of-sequence packets, while 520 * tracking the number if in-sequence packets after the first OOS packet 521 * is seen. After nr_oos_count_max in-sequence packets, reset the 522 * sequence number to re-enable packet reception. 523 */ 524 if (L2TP_SKB_CB(skb)->ns == session->nr) { 525 skb_queue_tail(&session->reorder_q, skb); 526 } else { 527 u32 nr_oos = L2TP_SKB_CB(skb)->ns; 528 u32 nr_next = (session->nr_oos + 1) & session->nr_max; 529 530 if (nr_oos == nr_next) 531 session->nr_oos_count++; 532 else 533 session->nr_oos_count = 0; 534 535 session->nr_oos = nr_oos; 536 if (session->nr_oos_count > session->nr_oos_count_max) { 537 session->reorder_skip = 1; 538 l2tp_dbg(session, L2TP_MSG_SEQ, 539 "%s: %d oos packets received. Resetting sequence numbers\n", 540 session->name, session->nr_oos_count); 541 } 542 if (!session->reorder_skip) { 543 atomic_long_inc(&session->stats.rx_seq_discards); 544 l2tp_dbg(session, L2TP_MSG_SEQ, 545 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n", 546 session->name, L2TP_SKB_CB(skb)->ns, 547 L2TP_SKB_CB(skb)->length, session->nr, 548 skb_queue_len(&session->reorder_q)); 549 goto discard; 550 } 551 skb_queue_tail(&session->reorder_q, skb); 552 } 553 554 out: 555 return 0; 556 557 discard: 558 return 1; 559 } 560 561 /* Do receive processing of L2TP data frames. We handle both L2TPv2 562 * and L2TPv3 data frames here. 563 * 564 * L2TPv2 Data Message Header 565 * 566 * 0 1 2 3 567 * 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 1 568 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 569 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) | 570 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 571 * | Tunnel ID | Session ID | 572 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 573 * | Ns (opt) | Nr (opt) | 574 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 575 * | Offset Size (opt) | Offset pad... (opt) 576 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 577 * 578 * Data frames are marked by T=0. All other fields are the same as 579 * those in L2TP control frames. 580 * 581 * L2TPv3 Data Message Header 582 * 583 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 584 * | L2TP Session Header | 585 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 586 * | L2-Specific Sublayer | 587 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 588 * | Tunnel Payload ... 589 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 590 * 591 * L2TPv3 Session Header Over IP 592 * 593 * 0 1 2 3 594 * 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 1 595 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 596 * | Session ID | 597 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 598 * | Cookie (optional, maximum 64 bits)... 599 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 600 * | 601 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 602 * 603 * L2TPv3 L2-Specific Sublayer Format 604 * 605 * 0 1 2 3 606 * 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 1 607 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 608 * |x|S|x|x|x|x|x|x| Sequence Number | 609 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 610 * 611 * Cookie value and sublayer format are negotiated with the peer when 612 * the session is set up. Unlike L2TPv2, we do not need to parse the 613 * packet header to determine if optional fields are present. 614 * 615 * Caller must already have parsed the frame and determined that it is 616 * a data (not control) frame before coming here. Fields up to the 617 * session-id have already been parsed and ptr points to the data 618 * after the session-id. 619 */ 620 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 621 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 622 int length, int (*payload_hook)(struct sk_buff *skb)) 623 { 624 struct l2tp_tunnel *tunnel = session->tunnel; 625 int offset; 626 u32 ns, nr; 627 628 /* Parse and check optional cookie */ 629 if (session->peer_cookie_len > 0) { 630 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { 631 l2tp_info(tunnel, L2TP_MSG_DATA, 632 "%s: cookie mismatch (%u/%u). Discarding.\n", 633 tunnel->name, tunnel->tunnel_id, 634 session->session_id); 635 atomic_long_inc(&session->stats.rx_cookie_discards); 636 goto discard; 637 } 638 ptr += session->peer_cookie_len; 639 } 640 641 /* Handle the optional sequence numbers. Sequence numbers are 642 * in different places for L2TPv2 and L2TPv3. 643 * 644 * If we are the LAC, enable/disable sequence numbers under 645 * the control of the LNS. If no sequence numbers present but 646 * we were expecting them, discard frame. 647 */ 648 ns = nr = 0; 649 L2TP_SKB_CB(skb)->has_seq = 0; 650 if (tunnel->version == L2TP_HDR_VER_2) { 651 if (hdrflags & L2TP_HDRFLAG_S) { 652 ns = ntohs(*(__be16 *) ptr); 653 ptr += 2; 654 nr = ntohs(*(__be16 *) ptr); 655 ptr += 2; 656 657 /* Store L2TP info in the skb */ 658 L2TP_SKB_CB(skb)->ns = ns; 659 L2TP_SKB_CB(skb)->has_seq = 1; 660 661 l2tp_dbg(session, L2TP_MSG_SEQ, 662 "%s: recv data ns=%u, nr=%u, session nr=%u\n", 663 session->name, ns, nr, session->nr); 664 } 665 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 666 u32 l2h = ntohl(*(__be32 *) ptr); 667 668 if (l2h & 0x40000000) { 669 ns = l2h & 0x00ffffff; 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, session nr=%u\n", 677 session->name, ns, session->nr); 678 } 679 ptr += 4; 680 } 681 682 if (L2TP_SKB_CB(skb)->has_seq) { 683 /* Received a packet with sequence numbers. If we're the LNS, 684 * check if we sre sending sequence numbers and if not, 685 * configure it so. 686 */ 687 if ((!session->lns_mode) && (!session->send_seq)) { 688 l2tp_info(session, L2TP_MSG_SEQ, 689 "%s: requested to enable seq numbers by LNS\n", 690 session->name); 691 session->send_seq = 1; 692 l2tp_session_set_header_len(session, tunnel->version); 693 } 694 } else { 695 /* No sequence numbers. 696 * If user has configured mandatory sequence numbers, discard. 697 */ 698 if (session->recv_seq) { 699 l2tp_warn(session, L2TP_MSG_SEQ, 700 "%s: recv data has no seq numbers when required. Discarding.\n", 701 session->name); 702 atomic_long_inc(&session->stats.rx_seq_discards); 703 goto discard; 704 } 705 706 /* If we're the LAC and we're sending sequence numbers, the 707 * LNS has requested that we no longer send sequence numbers. 708 * If we're the LNS and we're sending sequence numbers, the 709 * LAC is broken. Discard the frame. 710 */ 711 if ((!session->lns_mode) && (session->send_seq)) { 712 l2tp_info(session, L2TP_MSG_SEQ, 713 "%s: requested to disable seq numbers by LNS\n", 714 session->name); 715 session->send_seq = 0; 716 l2tp_session_set_header_len(session, tunnel->version); 717 } else if (session->send_seq) { 718 l2tp_warn(session, L2TP_MSG_SEQ, 719 "%s: recv data has no seq numbers when required. Discarding.\n", 720 session->name); 721 atomic_long_inc(&session->stats.rx_seq_discards); 722 goto discard; 723 } 724 } 725 726 /* Session data offset is defined only for L2TPv2 and is 727 * indicated by an optional 16-bit value in the header. 728 */ 729 if (tunnel->version == L2TP_HDR_VER_2) { 730 /* If offset bit set, skip it. */ 731 if (hdrflags & L2TP_HDRFLAG_O) { 732 offset = ntohs(*(__be16 *)ptr); 733 ptr += 2 + offset; 734 } 735 } 736 737 offset = ptr - optr; 738 if (!pskb_may_pull(skb, offset)) 739 goto discard; 740 741 __skb_pull(skb, offset); 742 743 /* If caller wants to process the payload before we queue the 744 * packet, do so now. 745 */ 746 if (payload_hook) 747 if ((*payload_hook)(skb)) 748 goto discard; 749 750 /* Prepare skb for adding to the session's reorder_q. Hold 751 * packets for max reorder_timeout or 1 second if not 752 * reordering. 753 */ 754 L2TP_SKB_CB(skb)->length = length; 755 L2TP_SKB_CB(skb)->expires = jiffies + 756 (session->reorder_timeout ? session->reorder_timeout : HZ); 757 758 /* Add packet to the session's receive queue. Reordering is done here, if 759 * enabled. Saved L2TP protocol info is stored in skb->sb[]. 760 */ 761 if (L2TP_SKB_CB(skb)->has_seq) { 762 if (l2tp_recv_data_seq(session, skb)) 763 goto discard; 764 } else { 765 /* No sequence numbers. Add the skb to the tail of the 766 * reorder queue. This ensures that it will be 767 * delivered after all previous sequenced skbs. 768 */ 769 skb_queue_tail(&session->reorder_q, skb); 770 } 771 772 /* Try to dequeue as many skbs from reorder_q as we can. */ 773 l2tp_recv_dequeue(session); 774 775 return; 776 777 discard: 778 atomic_long_inc(&session->stats.rx_errors); 779 kfree_skb(skb); 780 } 781 EXPORT_SYMBOL(l2tp_recv_common); 782 783 /* Drop skbs from the session's reorder_q 784 */ 785 static int l2tp_session_queue_purge(struct l2tp_session *session) 786 { 787 struct sk_buff *skb = NULL; 788 BUG_ON(!session); 789 BUG_ON(session->magic != L2TP_SESSION_MAGIC); 790 while ((skb = skb_dequeue(&session->reorder_q))) { 791 atomic_long_inc(&session->stats.rx_errors); 792 kfree_skb(skb); 793 } 794 return 0; 795 } 796 797 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame 798 * here. The skb is not on a list when we get here. 799 * Returns 0 if the packet was a data packet and was successfully passed on. 800 * Returns 1 if the packet was not a good data packet and could not be 801 * forwarded. All such packets are passed up to userspace to deal with. 802 */ 803 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, 804 int (*payload_hook)(struct sk_buff *skb)) 805 { 806 struct l2tp_session *session = NULL; 807 unsigned char *ptr, *optr; 808 u16 hdrflags; 809 u32 tunnel_id, session_id; 810 u16 version; 811 int length; 812 813 /* UDP has verifed checksum */ 814 815 /* UDP always verifies the packet length. */ 816 __skb_pull(skb, sizeof(struct udphdr)); 817 818 /* Short packet? */ 819 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) { 820 l2tp_info(tunnel, L2TP_MSG_DATA, 821 "%s: recv short packet (len=%d)\n", 822 tunnel->name, skb->len); 823 goto error; 824 } 825 826 /* Trace packet contents, if enabled */ 827 if (tunnel->debug & L2TP_MSG_DATA) { 828 length = min(32u, skb->len); 829 if (!pskb_may_pull(skb, length)) 830 goto error; 831 832 pr_debug("%s: recv\n", tunnel->name); 833 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 834 } 835 836 /* Point to L2TP header */ 837 optr = ptr = skb->data; 838 839 /* Get L2TP header flags */ 840 hdrflags = ntohs(*(__be16 *) ptr); 841 842 /* Check protocol version */ 843 version = hdrflags & L2TP_HDR_VER_MASK; 844 if (version != tunnel->version) { 845 l2tp_info(tunnel, L2TP_MSG_DATA, 846 "%s: recv protocol version mismatch: got %d expected %d\n", 847 tunnel->name, version, tunnel->version); 848 goto error; 849 } 850 851 /* Get length of L2TP packet */ 852 length = skb->len; 853 854 /* If type is control packet, it is handled by userspace. */ 855 if (hdrflags & L2TP_HDRFLAG_T) { 856 l2tp_dbg(tunnel, L2TP_MSG_DATA, 857 "%s: recv control packet, len=%d\n", 858 tunnel->name, length); 859 goto error; 860 } 861 862 /* Skip flags */ 863 ptr += 2; 864 865 if (tunnel->version == L2TP_HDR_VER_2) { 866 /* If length is present, skip it */ 867 if (hdrflags & L2TP_HDRFLAG_L) 868 ptr += 2; 869 870 /* Extract tunnel and session ID */ 871 tunnel_id = ntohs(*(__be16 *) ptr); 872 ptr += 2; 873 session_id = ntohs(*(__be16 *) ptr); 874 ptr += 2; 875 } else { 876 ptr += 2; /* skip reserved bits */ 877 tunnel_id = tunnel->tunnel_id; 878 session_id = ntohl(*(__be32 *) ptr); 879 ptr += 4; 880 } 881 882 /* Find the session context */ 883 session = l2tp_session_get(tunnel->l2tp_net, tunnel, session_id); 884 if (!session || !session->recv_skb) { 885 if (session) 886 l2tp_session_dec_refcount(session); 887 888 /* Not found? Pass to userspace to deal with */ 889 l2tp_info(tunnel, L2TP_MSG_DATA, 890 "%s: no session found (%u/%u). Passing up.\n", 891 tunnel->name, tunnel_id, session_id); 892 goto error; 893 } 894 895 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook); 896 l2tp_session_dec_refcount(session); 897 898 return 0; 899 900 error: 901 /* Put UDP header back */ 902 __skb_push(skb, sizeof(struct udphdr)); 903 904 return 1; 905 } 906 907 /* UDP encapsulation receive handler. See net/ipv4/udp.c. 908 * Return codes: 909 * 0 : success. 910 * <0: error 911 * >0: skb should be passed up to userspace as UDP. 912 */ 913 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 914 { 915 struct l2tp_tunnel *tunnel; 916 917 tunnel = l2tp_tunnel(sk); 918 if (tunnel == NULL) 919 goto pass_up; 920 921 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n", 922 tunnel->name, skb->len); 923 924 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook)) 925 goto pass_up; 926 927 return 0; 928 929 pass_up: 930 return 1; 931 } 932 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 933 934 /************************************************************************ 935 * Transmit handling 936 ***********************************************************************/ 937 938 /* Build an L2TP header for the session into the buffer provided. 939 */ 940 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 941 { 942 struct l2tp_tunnel *tunnel = session->tunnel; 943 __be16 *bufp = buf; 944 __be16 *optr = buf; 945 u16 flags = L2TP_HDR_VER_2; 946 u32 tunnel_id = tunnel->peer_tunnel_id; 947 u32 session_id = session->peer_session_id; 948 949 if (session->send_seq) 950 flags |= L2TP_HDRFLAG_S; 951 952 /* Setup L2TP header. */ 953 *bufp++ = htons(flags); 954 *bufp++ = htons(tunnel_id); 955 *bufp++ = htons(session_id); 956 if (session->send_seq) { 957 *bufp++ = htons(session->ns); 958 *bufp++ = 0; 959 session->ns++; 960 session->ns &= 0xffff; 961 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n", 962 session->name, session->ns); 963 } 964 965 return bufp - optr; 966 } 967 968 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 969 { 970 struct l2tp_tunnel *tunnel = session->tunnel; 971 char *bufp = buf; 972 char *optr = bufp; 973 974 /* Setup L2TP header. The header differs slightly for UDP and 975 * IP encapsulations. For UDP, there is 4 bytes of flags. 976 */ 977 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 978 u16 flags = L2TP_HDR_VER_3; 979 *((__be16 *) bufp) = htons(flags); 980 bufp += 2; 981 *((__be16 *) bufp) = 0; 982 bufp += 2; 983 } 984 985 *((__be32 *) bufp) = htonl(session->peer_session_id); 986 bufp += 4; 987 if (session->cookie_len) { 988 memcpy(bufp, &session->cookie[0], session->cookie_len); 989 bufp += session->cookie_len; 990 } 991 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 992 u32 l2h = 0; 993 994 if (session->send_seq) { 995 l2h = 0x40000000 | session->ns; 996 session->ns++; 997 session->ns &= 0xffffff; 998 l2tp_dbg(session, L2TP_MSG_SEQ, 999 "%s: updated ns to %u\n", 1000 session->name, session->ns); 1001 } 1002 1003 *((__be32 *)bufp) = htonl(l2h); 1004 bufp += 4; 1005 } 1006 1007 return bufp - optr; 1008 } 1009 1010 static void l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, 1011 struct flowi *fl, size_t data_len) 1012 { 1013 struct l2tp_tunnel *tunnel = session->tunnel; 1014 unsigned int len = skb->len; 1015 int error; 1016 1017 /* Debug */ 1018 if (session->send_seq) 1019 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes, ns=%u\n", 1020 session->name, data_len, session->ns - 1); 1021 else 1022 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes\n", 1023 session->name, data_len); 1024 1025 if (session->debug & L2TP_MSG_DATA) { 1026 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1027 unsigned char *datap = skb->data + uhlen; 1028 1029 pr_debug("%s: xmit\n", session->name); 1030 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, 1031 datap, min_t(size_t, 32, len - uhlen)); 1032 } 1033 1034 /* Queue the packet to IP for output */ 1035 skb->ignore_df = 1; 1036 #if IS_ENABLED(CONFIG_IPV6) 1037 if (l2tp_sk_is_v6(tunnel->sock)) 1038 error = inet6_csk_xmit(tunnel->sock, skb, NULL); 1039 else 1040 #endif 1041 error = ip_queue_xmit(tunnel->sock, skb, fl); 1042 1043 /* Update stats */ 1044 if (error >= 0) { 1045 atomic_long_inc(&tunnel->stats.tx_packets); 1046 atomic_long_add(len, &tunnel->stats.tx_bytes); 1047 atomic_long_inc(&session->stats.tx_packets); 1048 atomic_long_add(len, &session->stats.tx_bytes); 1049 } else { 1050 atomic_long_inc(&tunnel->stats.tx_errors); 1051 atomic_long_inc(&session->stats.tx_errors); 1052 } 1053 } 1054 1055 /* If caller requires the skb to have a ppp header, the header must be 1056 * inserted in the skb data before calling this function. 1057 */ 1058 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len) 1059 { 1060 int data_len = skb->len; 1061 struct l2tp_tunnel *tunnel = session->tunnel; 1062 struct sock *sk = tunnel->sock; 1063 struct flowi *fl; 1064 struct udphdr *uh; 1065 struct inet_sock *inet; 1066 int headroom; 1067 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1068 int udp_len; 1069 int ret = NET_XMIT_SUCCESS; 1070 1071 /* Check that there's enough headroom in the skb to insert IP, 1072 * UDP and L2TP headers. If not enough, expand it to 1073 * make room. Adjust truesize. 1074 */ 1075 headroom = NET_SKB_PAD + sizeof(struct iphdr) + 1076 uhlen + hdr_len; 1077 if (skb_cow_head(skb, headroom)) { 1078 kfree_skb(skb); 1079 return NET_XMIT_DROP; 1080 } 1081 1082 /* Setup L2TP header */ 1083 session->build_header(session, __skb_push(skb, hdr_len)); 1084 1085 /* Reset skb netfilter state */ 1086 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1087 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | 1088 IPSKB_REROUTED); 1089 nf_reset(skb); 1090 1091 bh_lock_sock(sk); 1092 if (sock_owned_by_user(sk)) { 1093 kfree_skb(skb); 1094 ret = NET_XMIT_DROP; 1095 goto out_unlock; 1096 } 1097 1098 /* The user-space may change the connection status for the user-space 1099 * provided socket at run time: we must check it under the socket lock 1100 */ 1101 if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) { 1102 kfree_skb(skb); 1103 ret = NET_XMIT_DROP; 1104 goto out_unlock; 1105 } 1106 1107 /* Get routing info from the tunnel socket */ 1108 skb_dst_drop(skb); 1109 skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0))); 1110 1111 inet = inet_sk(sk); 1112 fl = &inet->cork.fl; 1113 switch (tunnel->encap) { 1114 case L2TP_ENCAPTYPE_UDP: 1115 /* Setup UDP header */ 1116 __skb_push(skb, sizeof(*uh)); 1117 skb_reset_transport_header(skb); 1118 uh = udp_hdr(skb); 1119 uh->source = inet->inet_sport; 1120 uh->dest = inet->inet_dport; 1121 udp_len = uhlen + hdr_len + data_len; 1122 uh->len = htons(udp_len); 1123 1124 /* Calculate UDP checksum if configured to do so */ 1125 #if IS_ENABLED(CONFIG_IPV6) 1126 if (l2tp_sk_is_v6(sk)) 1127 udp6_set_csum(udp_get_no_check6_tx(sk), 1128 skb, &inet6_sk(sk)->saddr, 1129 &sk->sk_v6_daddr, udp_len); 1130 else 1131 #endif 1132 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr, 1133 inet->inet_daddr, udp_len); 1134 break; 1135 1136 case L2TP_ENCAPTYPE_IP: 1137 break; 1138 } 1139 1140 l2tp_xmit_core(session, skb, fl, data_len); 1141 out_unlock: 1142 bh_unlock_sock(sk); 1143 1144 return ret; 1145 } 1146 EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1147 1148 /***************************************************************************** 1149 * Tinnel and session create/destroy. 1150 *****************************************************************************/ 1151 1152 /* Tunnel socket destruct hook. 1153 * The tunnel context is deleted only when all session sockets have been 1154 * closed. 1155 */ 1156 static void l2tp_tunnel_destruct(struct sock *sk) 1157 { 1158 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1159 1160 if (tunnel == NULL) 1161 goto end; 1162 1163 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name); 1164 1165 /* Disable udp encapsulation */ 1166 switch (tunnel->encap) { 1167 case L2TP_ENCAPTYPE_UDP: 1168 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1169 (udp_sk(sk))->encap_type = 0; 1170 (udp_sk(sk))->encap_rcv = NULL; 1171 (udp_sk(sk))->encap_destroy = NULL; 1172 break; 1173 case L2TP_ENCAPTYPE_IP: 1174 break; 1175 } 1176 1177 /* Remove hooks into tunnel socket */ 1178 sk->sk_destruct = tunnel->old_sk_destruct; 1179 sk->sk_user_data = NULL; 1180 1181 /* Call the original destructor */ 1182 if (sk->sk_destruct) 1183 (*sk->sk_destruct)(sk); 1184 1185 kfree_rcu(tunnel, rcu); 1186 end: 1187 return; 1188 } 1189 1190 /* When the tunnel is closed, all the attached sessions need to go too. 1191 */ 1192 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1193 { 1194 int hash; 1195 struct hlist_node *walk; 1196 struct hlist_node *tmp; 1197 struct l2tp_session *session; 1198 1199 BUG_ON(tunnel == NULL); 1200 1201 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n", 1202 tunnel->name); 1203 1204 write_lock_bh(&tunnel->hlist_lock); 1205 tunnel->acpt_newsess = false; 1206 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1207 again: 1208 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) { 1209 session = hlist_entry(walk, struct l2tp_session, hlist); 1210 1211 l2tp_info(session, L2TP_MSG_CONTROL, 1212 "%s: closing session\n", session->name); 1213 1214 hlist_del_init(&session->hlist); 1215 1216 if (test_and_set_bit(0, &session->dead)) 1217 goto again; 1218 1219 write_unlock_bh(&tunnel->hlist_lock); 1220 1221 __l2tp_session_unhash(session); 1222 l2tp_session_queue_purge(session); 1223 1224 if (session->session_close != NULL) 1225 (*session->session_close)(session); 1226 1227 l2tp_session_dec_refcount(session); 1228 1229 write_lock_bh(&tunnel->hlist_lock); 1230 1231 /* Now restart from the beginning of this hash 1232 * chain. We always remove a session from the 1233 * list so we are guaranteed to make forward 1234 * progress. 1235 */ 1236 goto again; 1237 } 1238 } 1239 write_unlock_bh(&tunnel->hlist_lock); 1240 } 1241 1242 /* Tunnel socket destroy hook for UDP encapsulation */ 1243 static void l2tp_udp_encap_destroy(struct sock *sk) 1244 { 1245 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1246 1247 if (tunnel) 1248 l2tp_tunnel_delete(tunnel); 1249 } 1250 1251 /* Workqueue tunnel deletion function */ 1252 static void l2tp_tunnel_del_work(struct work_struct *work) 1253 { 1254 struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, 1255 del_work); 1256 struct sock *sk = tunnel->sock; 1257 struct socket *sock = sk->sk_socket; 1258 struct l2tp_net *pn; 1259 1260 l2tp_tunnel_closeall(tunnel); 1261 1262 /* If the tunnel socket was created within the kernel, use 1263 * the sk API to release it here. 1264 */ 1265 if (tunnel->fd < 0) { 1266 if (sock) { 1267 kernel_sock_shutdown(sock, SHUT_RDWR); 1268 sock_release(sock); 1269 } 1270 } 1271 1272 /* Remove the tunnel struct from the tunnel list */ 1273 pn = l2tp_pernet(tunnel->l2tp_net); 1274 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1275 list_del_rcu(&tunnel->list); 1276 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1277 1278 /* drop initial ref */ 1279 l2tp_tunnel_dec_refcount(tunnel); 1280 1281 /* drop workqueue ref */ 1282 l2tp_tunnel_dec_refcount(tunnel); 1283 } 1284 1285 /* Create a socket for the tunnel, if one isn't set up by 1286 * userspace. This is used for static tunnels where there is no 1287 * managing L2TP daemon. 1288 * 1289 * Since we don't want these sockets to keep a namespace alive by 1290 * themselves, we drop the socket's namespace refcount after creation. 1291 * These sockets are freed when the namespace exits using the pernet 1292 * exit hook. 1293 */ 1294 static int l2tp_tunnel_sock_create(struct net *net, 1295 u32 tunnel_id, 1296 u32 peer_tunnel_id, 1297 struct l2tp_tunnel_cfg *cfg, 1298 struct socket **sockp) 1299 { 1300 int err = -EINVAL; 1301 struct socket *sock = NULL; 1302 struct udp_port_cfg udp_conf; 1303 1304 switch (cfg->encap) { 1305 case L2TP_ENCAPTYPE_UDP: 1306 memset(&udp_conf, 0, sizeof(udp_conf)); 1307 1308 #if IS_ENABLED(CONFIG_IPV6) 1309 if (cfg->local_ip6 && cfg->peer_ip6) { 1310 udp_conf.family = AF_INET6; 1311 memcpy(&udp_conf.local_ip6, cfg->local_ip6, 1312 sizeof(udp_conf.local_ip6)); 1313 memcpy(&udp_conf.peer_ip6, cfg->peer_ip6, 1314 sizeof(udp_conf.peer_ip6)); 1315 udp_conf.use_udp6_tx_checksums = 1316 ! cfg->udp6_zero_tx_checksums; 1317 udp_conf.use_udp6_rx_checksums = 1318 ! cfg->udp6_zero_rx_checksums; 1319 } else 1320 #endif 1321 { 1322 udp_conf.family = AF_INET; 1323 udp_conf.local_ip = cfg->local_ip; 1324 udp_conf.peer_ip = cfg->peer_ip; 1325 udp_conf.use_udp_checksums = cfg->use_udp_checksums; 1326 } 1327 1328 udp_conf.local_udp_port = htons(cfg->local_udp_port); 1329 udp_conf.peer_udp_port = htons(cfg->peer_udp_port); 1330 1331 err = udp_sock_create(net, &udp_conf, &sock); 1332 if (err < 0) 1333 goto out; 1334 1335 break; 1336 1337 case L2TP_ENCAPTYPE_IP: 1338 #if IS_ENABLED(CONFIG_IPV6) 1339 if (cfg->local_ip6 && cfg->peer_ip6) { 1340 struct sockaddr_l2tpip6 ip6_addr = {0}; 1341 1342 err = sock_create_kern(net, AF_INET6, SOCK_DGRAM, 1343 IPPROTO_L2TP, &sock); 1344 if (err < 0) 1345 goto out; 1346 1347 ip6_addr.l2tp_family = AF_INET6; 1348 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6, 1349 sizeof(ip6_addr.l2tp_addr)); 1350 ip6_addr.l2tp_conn_id = tunnel_id; 1351 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr, 1352 sizeof(ip6_addr)); 1353 if (err < 0) 1354 goto out; 1355 1356 ip6_addr.l2tp_family = AF_INET6; 1357 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6, 1358 sizeof(ip6_addr.l2tp_addr)); 1359 ip6_addr.l2tp_conn_id = peer_tunnel_id; 1360 err = kernel_connect(sock, 1361 (struct sockaddr *) &ip6_addr, 1362 sizeof(ip6_addr), 0); 1363 if (err < 0) 1364 goto out; 1365 } else 1366 #endif 1367 { 1368 struct sockaddr_l2tpip ip_addr = {0}; 1369 1370 err = sock_create_kern(net, AF_INET, SOCK_DGRAM, 1371 IPPROTO_L2TP, &sock); 1372 if (err < 0) 1373 goto out; 1374 1375 ip_addr.l2tp_family = AF_INET; 1376 ip_addr.l2tp_addr = cfg->local_ip; 1377 ip_addr.l2tp_conn_id = tunnel_id; 1378 err = kernel_bind(sock, (struct sockaddr *) &ip_addr, 1379 sizeof(ip_addr)); 1380 if (err < 0) 1381 goto out; 1382 1383 ip_addr.l2tp_family = AF_INET; 1384 ip_addr.l2tp_addr = cfg->peer_ip; 1385 ip_addr.l2tp_conn_id = peer_tunnel_id; 1386 err = kernel_connect(sock, (struct sockaddr *) &ip_addr, 1387 sizeof(ip_addr), 0); 1388 if (err < 0) 1389 goto out; 1390 } 1391 break; 1392 1393 default: 1394 goto out; 1395 } 1396 1397 out: 1398 *sockp = sock; 1399 if ((err < 0) && sock) { 1400 kernel_sock_shutdown(sock, SHUT_RDWR); 1401 sock_release(sock); 1402 *sockp = NULL; 1403 } 1404 1405 return err; 1406 } 1407 1408 static struct lock_class_key l2tp_socket_class; 1409 1410 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) 1411 { 1412 struct l2tp_tunnel *tunnel = NULL; 1413 int err; 1414 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1415 1416 if (cfg != NULL) 1417 encap = cfg->encap; 1418 1419 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL); 1420 if (tunnel == NULL) { 1421 err = -ENOMEM; 1422 goto err; 1423 } 1424 1425 tunnel->version = version; 1426 tunnel->tunnel_id = tunnel_id; 1427 tunnel->peer_tunnel_id = peer_tunnel_id; 1428 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS; 1429 1430 tunnel->magic = L2TP_TUNNEL_MAGIC; 1431 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1432 rwlock_init(&tunnel->hlist_lock); 1433 tunnel->acpt_newsess = true; 1434 1435 if (cfg != NULL) 1436 tunnel->debug = cfg->debug; 1437 1438 tunnel->encap = encap; 1439 1440 refcount_set(&tunnel->ref_count, 1); 1441 tunnel->fd = fd; 1442 1443 /* Init delete workqueue struct */ 1444 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); 1445 1446 INIT_LIST_HEAD(&tunnel->list); 1447 1448 err = 0; 1449 err: 1450 if (tunnelp) 1451 *tunnelp = tunnel; 1452 1453 return err; 1454 } 1455 EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1456 1457 static int l2tp_validate_socket(const struct sock *sk, const struct net *net, 1458 enum l2tp_encap_type encap) 1459 { 1460 if (!net_eq(sock_net(sk), net)) 1461 return -EINVAL; 1462 1463 if (sk->sk_type != SOCK_DGRAM) 1464 return -EPROTONOSUPPORT; 1465 1466 if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) || 1467 (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP)) 1468 return -EPROTONOSUPPORT; 1469 1470 if (sk->sk_user_data) 1471 return -EBUSY; 1472 1473 return 0; 1474 } 1475 1476 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 1477 struct l2tp_tunnel_cfg *cfg) 1478 { 1479 struct l2tp_tunnel *tunnel_walk; 1480 struct l2tp_net *pn; 1481 struct socket *sock; 1482 struct sock *sk; 1483 int ret; 1484 1485 if (tunnel->fd < 0) { 1486 ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id, 1487 tunnel->peer_tunnel_id, cfg, 1488 &sock); 1489 if (ret < 0) 1490 goto err; 1491 } else { 1492 sock = sockfd_lookup(tunnel->fd, &ret); 1493 if (!sock) 1494 goto err; 1495 1496 ret = l2tp_validate_socket(sock->sk, net, tunnel->encap); 1497 if (ret < 0) 1498 goto err_sock; 1499 } 1500 1501 sk = sock->sk; 1502 1503 sock_hold(sk); 1504 tunnel->sock = sk; 1505 tunnel->l2tp_net = net; 1506 1507 pn = l2tp_pernet(net); 1508 1509 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1510 list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) { 1511 if (tunnel_walk->tunnel_id == tunnel->tunnel_id) { 1512 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1513 1514 ret = -EEXIST; 1515 goto err_sock; 1516 } 1517 } 1518 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); 1519 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1520 1521 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1522 struct udp_tunnel_sock_cfg udp_cfg = { 1523 .sk_user_data = tunnel, 1524 .encap_type = UDP_ENCAP_L2TPINUDP, 1525 .encap_rcv = l2tp_udp_encap_recv, 1526 .encap_destroy = l2tp_udp_encap_destroy, 1527 }; 1528 1529 setup_udp_tunnel_sock(net, sock, &udp_cfg); 1530 } else { 1531 sk->sk_user_data = tunnel; 1532 } 1533 1534 tunnel->old_sk_destruct = sk->sk_destruct; 1535 sk->sk_destruct = &l2tp_tunnel_destruct; 1536 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, 1537 "l2tp_sock"); 1538 sk->sk_allocation = GFP_ATOMIC; 1539 1540 if (tunnel->fd >= 0) 1541 sockfd_put(sock); 1542 1543 return 0; 1544 1545 err_sock: 1546 if (tunnel->fd < 0) 1547 sock_release(sock); 1548 else 1549 sockfd_put(sock); 1550 err: 1551 return ret; 1552 } 1553 EXPORT_SYMBOL_GPL(l2tp_tunnel_register); 1554 1555 /* This function is used by the netlink TUNNEL_DELETE command. 1556 */ 1557 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1558 { 1559 if (!test_and_set_bit(0, &tunnel->dead)) { 1560 l2tp_tunnel_inc_refcount(tunnel); 1561 queue_work(l2tp_wq, &tunnel->del_work); 1562 } 1563 } 1564 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1565 1566 /* Really kill the session. 1567 */ 1568 void l2tp_session_free(struct l2tp_session *session) 1569 { 1570 struct l2tp_tunnel *tunnel = session->tunnel; 1571 1572 BUG_ON(refcount_read(&session->ref_count) != 0); 1573 1574 if (tunnel) { 1575 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC); 1576 l2tp_tunnel_dec_refcount(tunnel); 1577 } 1578 1579 kfree(session); 1580 } 1581 EXPORT_SYMBOL_GPL(l2tp_session_free); 1582 1583 /* Remove an l2tp session from l2tp_core's hash lists. 1584 * Provides a tidyup interface for pseudowire code which can't just route all 1585 * shutdown via. l2tp_session_delete and a pseudowire-specific session_close 1586 * callback. 1587 */ 1588 void __l2tp_session_unhash(struct l2tp_session *session) 1589 { 1590 struct l2tp_tunnel *tunnel = session->tunnel; 1591 1592 /* Remove the session from core hashes */ 1593 if (tunnel) { 1594 /* Remove from the per-tunnel hash */ 1595 write_lock_bh(&tunnel->hlist_lock); 1596 hlist_del_init(&session->hlist); 1597 write_unlock_bh(&tunnel->hlist_lock); 1598 1599 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1600 if (tunnel->version != L2TP_HDR_VER_2) { 1601 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1602 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1603 hlist_del_init_rcu(&session->global_hlist); 1604 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1605 synchronize_rcu(); 1606 } 1607 } 1608 } 1609 EXPORT_SYMBOL_GPL(__l2tp_session_unhash); 1610 1611 /* This function is used by the netlink SESSION_DELETE command and by 1612 pseudowire modules. 1613 */ 1614 int l2tp_session_delete(struct l2tp_session *session) 1615 { 1616 if (test_and_set_bit(0, &session->dead)) 1617 return 0; 1618 1619 __l2tp_session_unhash(session); 1620 l2tp_session_queue_purge(session); 1621 if (session->session_close != NULL) 1622 (*session->session_close)(session); 1623 1624 l2tp_session_dec_refcount(session); 1625 1626 return 0; 1627 } 1628 EXPORT_SYMBOL_GPL(l2tp_session_delete); 1629 1630 /* We come here whenever a session's send_seq, cookie_len or 1631 * l2specific_type parameters are set. 1632 */ 1633 void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1634 { 1635 if (version == L2TP_HDR_VER_2) { 1636 session->hdr_len = 6; 1637 if (session->send_seq) 1638 session->hdr_len += 4; 1639 } else { 1640 session->hdr_len = 4 + session->cookie_len; 1641 session->hdr_len += l2tp_get_l2specific_len(session); 1642 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1643 session->hdr_len += 4; 1644 } 1645 1646 } 1647 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1648 1649 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) 1650 { 1651 struct l2tp_session *session; 1652 1653 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL); 1654 if (session != NULL) { 1655 session->magic = L2TP_SESSION_MAGIC; 1656 session->tunnel = tunnel; 1657 1658 session->session_id = session_id; 1659 session->peer_session_id = peer_session_id; 1660 session->nr = 0; 1661 if (tunnel->version == L2TP_HDR_VER_2) 1662 session->nr_max = 0xffff; 1663 else 1664 session->nr_max = 0xffffff; 1665 session->nr_window_size = session->nr_max / 2; 1666 session->nr_oos_count_max = 4; 1667 1668 /* Use NR of first received packet */ 1669 session->reorder_skip = 1; 1670 1671 sprintf(&session->name[0], "sess %u/%u", 1672 tunnel->tunnel_id, session->session_id); 1673 1674 skb_queue_head_init(&session->reorder_q); 1675 1676 INIT_HLIST_NODE(&session->hlist); 1677 INIT_HLIST_NODE(&session->global_hlist); 1678 1679 /* Inherit debug options from tunnel */ 1680 session->debug = tunnel->debug; 1681 1682 if (cfg) { 1683 session->pwtype = cfg->pw_type; 1684 session->debug = cfg->debug; 1685 session->mtu = cfg->mtu; 1686 session->mru = cfg->mru; 1687 session->send_seq = cfg->send_seq; 1688 session->recv_seq = cfg->recv_seq; 1689 session->lns_mode = cfg->lns_mode; 1690 session->reorder_timeout = cfg->reorder_timeout; 1691 session->l2specific_type = cfg->l2specific_type; 1692 session->cookie_len = cfg->cookie_len; 1693 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1694 session->peer_cookie_len = cfg->peer_cookie_len; 1695 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1696 } 1697 1698 if (tunnel->version == L2TP_HDR_VER_2) 1699 session->build_header = l2tp_build_l2tpv2_header; 1700 else 1701 session->build_header = l2tp_build_l2tpv3_header; 1702 1703 l2tp_session_set_header_len(session, tunnel->version); 1704 1705 refcount_set(&session->ref_count, 1); 1706 1707 return session; 1708 } 1709 1710 return ERR_PTR(-ENOMEM); 1711 } 1712 EXPORT_SYMBOL_GPL(l2tp_session_create); 1713 1714 /***************************************************************************** 1715 * Init and cleanup 1716 *****************************************************************************/ 1717 1718 static __net_init int l2tp_init_net(struct net *net) 1719 { 1720 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1721 int hash; 1722 1723 INIT_LIST_HEAD(&pn->l2tp_tunnel_list); 1724 spin_lock_init(&pn->l2tp_tunnel_list_lock); 1725 1726 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1727 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1728 1729 spin_lock_init(&pn->l2tp_session_hlist_lock); 1730 1731 return 0; 1732 } 1733 1734 static __net_exit void l2tp_exit_net(struct net *net) 1735 { 1736 struct l2tp_net *pn = l2tp_pernet(net); 1737 struct l2tp_tunnel *tunnel = NULL; 1738 int hash; 1739 1740 rcu_read_lock_bh(); 1741 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 1742 l2tp_tunnel_delete(tunnel); 1743 } 1744 rcu_read_unlock_bh(); 1745 1746 flush_workqueue(l2tp_wq); 1747 rcu_barrier(); 1748 1749 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1750 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); 1751 } 1752 1753 static struct pernet_operations l2tp_net_ops = { 1754 .init = l2tp_init_net, 1755 .exit = l2tp_exit_net, 1756 .id = &l2tp_net_id, 1757 .size = sizeof(struct l2tp_net), 1758 }; 1759 1760 static int __init l2tp_init(void) 1761 { 1762 int rc = 0; 1763 1764 rc = register_pernet_device(&l2tp_net_ops); 1765 if (rc) 1766 goto out; 1767 1768 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1769 if (!l2tp_wq) { 1770 pr_err("alloc_workqueue failed\n"); 1771 unregister_pernet_device(&l2tp_net_ops); 1772 rc = -ENOMEM; 1773 goto out; 1774 } 1775 1776 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 1777 1778 out: 1779 return rc; 1780 } 1781 1782 static void __exit l2tp_exit(void) 1783 { 1784 unregister_pernet_device(&l2tp_net_ops); 1785 if (l2tp_wq) { 1786 destroy_workqueue(l2tp_wq); 1787 l2tp_wq = NULL; 1788 } 1789 } 1790 1791 module_init(l2tp_init); 1792 module_exit(l2tp_exit); 1793 1794 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1795 MODULE_DESCRIPTION("L2TP core"); 1796 MODULE_LICENSE("GPL"); 1797 MODULE_VERSION(L2TP_DRV_VERSION); 1798 1799