1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * L2TP core. 4 * 5 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd 6 * 7 * This file contains some code of the original L2TPv2 pppol2tp 8 * driver, which has the following copyright: 9 * 10 * Authors: Martijn van Oosterhout <kleptog@svana.org> 11 * James Chapman (jchapman@katalix.com) 12 * Contributors: 13 * Michal Ostrowski <mostrows@speakeasy.net> 14 * Arnaldo Carvalho de Melo <acme@xconectiva.com.br> 15 * David S. Miller (davem@redhat.com) 16 */ 17 18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 19 20 #include <linux/module.h> 21 #include <linux/string.h> 22 #include <linux/list.h> 23 #include <linux/rculist.h> 24 #include <linux/uaccess.h> 25 26 #include <linux/kernel.h> 27 #include <linux/spinlock.h> 28 #include <linux/kthread.h> 29 #include <linux/sched.h> 30 #include <linux/slab.h> 31 #include <linux/errno.h> 32 #include <linux/jiffies.h> 33 34 #include <linux/netdevice.h> 35 #include <linux/net.h> 36 #include <linux/inetdevice.h> 37 #include <linux/skbuff.h> 38 #include <linux/init.h> 39 #include <linux/in.h> 40 #include <linux/ip.h> 41 #include <linux/udp.h> 42 #include <linux/l2tp.h> 43 #include <linux/hash.h> 44 #include <linux/sort.h> 45 #include <linux/file.h> 46 #include <linux/nsproxy.h> 47 #include <net/net_namespace.h> 48 #include <net/netns/generic.h> 49 #include <net/dst.h> 50 #include <net/ip.h> 51 #include <net/udp.h> 52 #include <net/udp_tunnel.h> 53 #include <net/inet_common.h> 54 #include <net/xfrm.h> 55 #include <net/protocol.h> 56 #include <net/inet6_connection_sock.h> 57 #include <net/inet_ecn.h> 58 #include <net/ip6_route.h> 59 #include <net/ip6_checksum.h> 60 61 #include <asm/byteorder.h> 62 #include <linux/atomic.h> 63 64 #include "l2tp_core.h" 65 66 #define L2TP_DRV_VERSION "V2.0" 67 68 /* L2TP header constants */ 69 #define L2TP_HDRFLAG_T 0x8000 70 #define L2TP_HDRFLAG_L 0x4000 71 #define L2TP_HDRFLAG_S 0x0800 72 #define L2TP_HDRFLAG_O 0x0200 73 #define L2TP_HDRFLAG_P 0x0100 74 75 #define L2TP_HDR_VER_MASK 0x000F 76 #define L2TP_HDR_VER_2 0x0002 77 #define L2TP_HDR_VER_3 0x0003 78 79 /* L2TPv3 default L2-specific sublayer */ 80 #define L2TP_SLFLAG_S 0x40000000 81 #define L2TP_SL_SEQ_MASK 0x00ffffff 82 83 #define L2TP_HDR_SIZE_MAX 14 84 85 /* Default trace flags */ 86 #define L2TP_DEFAULT_DEBUG_FLAGS 0 87 88 /* Private data stored for received packets in the skb. 89 */ 90 struct l2tp_skb_cb { 91 u32 ns; 92 u16 has_seq; 93 u16 length; 94 unsigned long expires; 95 }; 96 97 #define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)]) 98 99 static struct workqueue_struct *l2tp_wq; 100 101 /* per-net private data for this module */ 102 static unsigned int l2tp_net_id; 103 struct l2tp_net { 104 struct list_head l2tp_tunnel_list; 105 spinlock_t l2tp_tunnel_list_lock; 106 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; 107 spinlock_t l2tp_session_hlist_lock; 108 }; 109 110 #if IS_ENABLED(CONFIG_IPV6) 111 static bool l2tp_sk_is_v6(struct sock *sk) 112 { 113 return sk->sk_family == PF_INET6 && 114 !ipv6_addr_v4mapped(&sk->sk_v6_daddr); 115 } 116 #endif 117 118 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk) 119 { 120 return sk->sk_user_data; 121 } 122 123 static inline struct l2tp_net *l2tp_pernet(const struct net *net) 124 { 125 BUG_ON(!net); 126 127 return net_generic(net, l2tp_net_id); 128 } 129 130 /* Session hash global list for L2TPv3. 131 * The session_id SHOULD be random according to RFC3931, but several 132 * L2TP implementations use incrementing session_ids. So we do a real 133 * hash on the session_id, rather than a simple bitmask. 134 */ 135 static inline struct hlist_head * 136 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id) 137 { 138 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)]; 139 140 } 141 142 /* Session hash list. 143 * The session_id SHOULD be random according to RFC2661, but several 144 * L2TP implementations (Cisco and Microsoft) use incrementing 145 * session_ids. So we do a real hash on the session_id, rather than a 146 * simple bitmask. 147 */ 148 static inline struct hlist_head * 149 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id) 150 { 151 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)]; 152 } 153 154 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) 155 { 156 sock_put(tunnel->sock); 157 /* the tunnel is freed in the socket destructor */ 158 } 159 EXPORT_SYMBOL(l2tp_tunnel_free); 160 161 /* Lookup a tunnel. A new reference is held on the returned tunnel. */ 162 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) 163 { 164 const struct l2tp_net *pn = l2tp_pernet(net); 165 struct l2tp_tunnel *tunnel; 166 167 rcu_read_lock_bh(); 168 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 169 if (tunnel->tunnel_id == tunnel_id && 170 refcount_inc_not_zero(&tunnel->ref_count)) { 171 rcu_read_unlock_bh(); 172 173 return tunnel; 174 } 175 } 176 rcu_read_unlock_bh(); 177 178 return NULL; 179 } 180 EXPORT_SYMBOL_GPL(l2tp_tunnel_get); 181 182 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) 183 { 184 const struct l2tp_net *pn = l2tp_pernet(net); 185 struct l2tp_tunnel *tunnel; 186 int count = 0; 187 188 rcu_read_lock_bh(); 189 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 190 if (++count > nth && 191 refcount_inc_not_zero(&tunnel->ref_count)) { 192 rcu_read_unlock_bh(); 193 return tunnel; 194 } 195 } 196 rcu_read_unlock_bh(); 197 198 return NULL; 199 } 200 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth); 201 202 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel, 203 u32 session_id) 204 { 205 struct hlist_head *session_list; 206 struct l2tp_session *session; 207 208 session_list = l2tp_session_id_hash(tunnel, session_id); 209 210 read_lock_bh(&tunnel->hlist_lock); 211 hlist_for_each_entry(session, session_list, hlist) 212 if (session->session_id == session_id) { 213 l2tp_session_inc_refcount(session); 214 read_unlock_bh(&tunnel->hlist_lock); 215 216 return session; 217 } 218 read_unlock_bh(&tunnel->hlist_lock); 219 220 return NULL; 221 } 222 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_session); 223 224 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id) 225 { 226 struct hlist_head *session_list; 227 struct l2tp_session *session; 228 229 session_list = l2tp_session_id_hash_2(l2tp_pernet(net), session_id); 230 231 rcu_read_lock_bh(); 232 hlist_for_each_entry_rcu(session, session_list, global_hlist) 233 if (session->session_id == session_id) { 234 l2tp_session_inc_refcount(session); 235 rcu_read_unlock_bh(); 236 237 return session; 238 } 239 rcu_read_unlock_bh(); 240 241 return NULL; 242 } 243 EXPORT_SYMBOL_GPL(l2tp_session_get); 244 245 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth) 246 { 247 int hash; 248 struct l2tp_session *session; 249 int count = 0; 250 251 read_lock_bh(&tunnel->hlist_lock); 252 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 253 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) { 254 if (++count > nth) { 255 l2tp_session_inc_refcount(session); 256 read_unlock_bh(&tunnel->hlist_lock); 257 return session; 258 } 259 } 260 } 261 262 read_unlock_bh(&tunnel->hlist_lock); 263 264 return NULL; 265 } 266 EXPORT_SYMBOL_GPL(l2tp_session_get_nth); 267 268 /* Lookup a session by interface name. 269 * This is very inefficient but is only used by management interfaces. 270 */ 271 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 272 const char *ifname) 273 { 274 struct l2tp_net *pn = l2tp_pernet(net); 275 int hash; 276 struct l2tp_session *session; 277 278 rcu_read_lock_bh(); 279 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { 280 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) { 281 if (!strcmp(session->ifname, ifname)) { 282 l2tp_session_inc_refcount(session); 283 rcu_read_unlock_bh(); 284 285 return session; 286 } 287 } 288 } 289 290 rcu_read_unlock_bh(); 291 292 return NULL; 293 } 294 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); 295 296 int l2tp_session_register(struct l2tp_session *session, 297 struct l2tp_tunnel *tunnel) 298 { 299 struct l2tp_session *session_walk; 300 struct hlist_head *g_head; 301 struct hlist_head *head; 302 struct l2tp_net *pn; 303 int err; 304 305 head = l2tp_session_id_hash(tunnel, session->session_id); 306 307 write_lock_bh(&tunnel->hlist_lock); 308 if (!tunnel->acpt_newsess) { 309 err = -ENODEV; 310 goto err_tlock; 311 } 312 313 hlist_for_each_entry(session_walk, head, hlist) 314 if (session_walk->session_id == session->session_id) { 315 err = -EEXIST; 316 goto err_tlock; 317 } 318 319 if (tunnel->version == L2TP_HDR_VER_3) { 320 pn = l2tp_pernet(tunnel->l2tp_net); 321 g_head = l2tp_session_id_hash_2(pn, session->session_id); 322 323 spin_lock_bh(&pn->l2tp_session_hlist_lock); 324 325 hlist_for_each_entry(session_walk, g_head, global_hlist) 326 if (session_walk->session_id == session->session_id) { 327 err = -EEXIST; 328 goto err_tlock_pnlock; 329 } 330 331 l2tp_tunnel_inc_refcount(tunnel); 332 hlist_add_head_rcu(&session->global_hlist, g_head); 333 334 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 335 } else { 336 l2tp_tunnel_inc_refcount(tunnel); 337 } 338 339 hlist_add_head(&session->hlist, head); 340 write_unlock_bh(&tunnel->hlist_lock); 341 342 return 0; 343 344 err_tlock_pnlock: 345 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 346 err_tlock: 347 write_unlock_bh(&tunnel->hlist_lock); 348 349 return err; 350 } 351 EXPORT_SYMBOL_GPL(l2tp_session_register); 352 353 /***************************************************************************** 354 * Receive data handling 355 *****************************************************************************/ 356 357 /* Queue a skb in order. We come here only if the skb has an L2TP sequence 358 * number. 359 */ 360 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb) 361 { 362 struct sk_buff *skbp; 363 struct sk_buff *tmp; 364 u32 ns = L2TP_SKB_CB(skb)->ns; 365 366 spin_lock_bh(&session->reorder_q.lock); 367 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) { 368 if (L2TP_SKB_CB(skbp)->ns > ns) { 369 __skb_queue_before(&session->reorder_q, skbp, skb); 370 l2tp_dbg(session, L2TP_MSG_SEQ, 371 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n", 372 session->name, ns, L2TP_SKB_CB(skbp)->ns, 373 skb_queue_len(&session->reorder_q)); 374 atomic_long_inc(&session->stats.rx_oos_packets); 375 goto out; 376 } 377 } 378 379 __skb_queue_tail(&session->reorder_q, skb); 380 381 out: 382 spin_unlock_bh(&session->reorder_q.lock); 383 } 384 385 /* Dequeue a single skb. 386 */ 387 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb) 388 { 389 struct l2tp_tunnel *tunnel = session->tunnel; 390 int length = L2TP_SKB_CB(skb)->length; 391 392 /* We're about to requeue the skb, so return resources 393 * to its current owner (a socket receive buffer). 394 */ 395 skb_orphan(skb); 396 397 atomic_long_inc(&tunnel->stats.rx_packets); 398 atomic_long_add(length, &tunnel->stats.rx_bytes); 399 atomic_long_inc(&session->stats.rx_packets); 400 atomic_long_add(length, &session->stats.rx_bytes); 401 402 if (L2TP_SKB_CB(skb)->has_seq) { 403 /* Bump our Nr */ 404 session->nr++; 405 session->nr &= session->nr_max; 406 407 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n", 408 session->name, session->nr); 409 } 410 411 /* call private receive handler */ 412 if (session->recv_skb != NULL) 413 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); 414 else 415 kfree_skb(skb); 416 } 417 418 /* Dequeue skbs from the session's reorder_q, subject to packet order. 419 * Skbs that have been in the queue for too long are simply discarded. 420 */ 421 static void l2tp_recv_dequeue(struct l2tp_session *session) 422 { 423 struct sk_buff *skb; 424 struct sk_buff *tmp; 425 426 /* If the pkt at the head of the queue has the nr that we 427 * expect to send up next, dequeue it and any other 428 * in-sequence packets behind it. 429 */ 430 start: 431 spin_lock_bh(&session->reorder_q.lock); 432 skb_queue_walk_safe(&session->reorder_q, skb, tmp) { 433 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) { 434 atomic_long_inc(&session->stats.rx_seq_discards); 435 atomic_long_inc(&session->stats.rx_errors); 436 l2tp_dbg(session, L2TP_MSG_SEQ, 437 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n", 438 session->name, L2TP_SKB_CB(skb)->ns, 439 L2TP_SKB_CB(skb)->length, session->nr, 440 skb_queue_len(&session->reorder_q)); 441 session->reorder_skip = 1; 442 __skb_unlink(skb, &session->reorder_q); 443 kfree_skb(skb); 444 continue; 445 } 446 447 if (L2TP_SKB_CB(skb)->has_seq) { 448 if (session->reorder_skip) { 449 l2tp_dbg(session, L2TP_MSG_SEQ, 450 "%s: advancing nr to next pkt: %u -> %u", 451 session->name, session->nr, 452 L2TP_SKB_CB(skb)->ns); 453 session->reorder_skip = 0; 454 session->nr = L2TP_SKB_CB(skb)->ns; 455 } 456 if (L2TP_SKB_CB(skb)->ns != session->nr) { 457 l2tp_dbg(session, L2TP_MSG_SEQ, 458 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n", 459 session->name, L2TP_SKB_CB(skb)->ns, 460 L2TP_SKB_CB(skb)->length, session->nr, 461 skb_queue_len(&session->reorder_q)); 462 goto out; 463 } 464 } 465 __skb_unlink(skb, &session->reorder_q); 466 467 /* Process the skb. We release the queue lock while we 468 * do so to let other contexts process the queue. 469 */ 470 spin_unlock_bh(&session->reorder_q.lock); 471 l2tp_recv_dequeue_skb(session, skb); 472 goto start; 473 } 474 475 out: 476 spin_unlock_bh(&session->reorder_q.lock); 477 } 478 479 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr) 480 { 481 u32 nws; 482 483 if (nr >= session->nr) 484 nws = nr - session->nr; 485 else 486 nws = (session->nr_max + 1) - (session->nr - nr); 487 488 return nws < session->nr_window_size; 489 } 490 491 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if 492 * acceptable, else non-zero. 493 */ 494 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb) 495 { 496 if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) { 497 /* Packet sequence number is outside allowed window. 498 * Discard it. 499 */ 500 l2tp_dbg(session, L2TP_MSG_SEQ, 501 "%s: pkt %u len %d discarded, outside window, nr=%u\n", 502 session->name, L2TP_SKB_CB(skb)->ns, 503 L2TP_SKB_CB(skb)->length, session->nr); 504 goto discard; 505 } 506 507 if (session->reorder_timeout != 0) { 508 /* Packet reordering enabled. Add skb to session's 509 * reorder queue, in order of ns. 510 */ 511 l2tp_recv_queue_skb(session, skb); 512 goto out; 513 } 514 515 /* Packet reordering disabled. Discard out-of-sequence packets, while 516 * tracking the number if in-sequence packets after the first OOS packet 517 * is seen. After nr_oos_count_max in-sequence packets, reset the 518 * sequence number to re-enable packet reception. 519 */ 520 if (L2TP_SKB_CB(skb)->ns == session->nr) { 521 skb_queue_tail(&session->reorder_q, skb); 522 } else { 523 u32 nr_oos = L2TP_SKB_CB(skb)->ns; 524 u32 nr_next = (session->nr_oos + 1) & session->nr_max; 525 526 if (nr_oos == nr_next) 527 session->nr_oos_count++; 528 else 529 session->nr_oos_count = 0; 530 531 session->nr_oos = nr_oos; 532 if (session->nr_oos_count > session->nr_oos_count_max) { 533 session->reorder_skip = 1; 534 l2tp_dbg(session, L2TP_MSG_SEQ, 535 "%s: %d oos packets received. Resetting sequence numbers\n", 536 session->name, session->nr_oos_count); 537 } 538 if (!session->reorder_skip) { 539 atomic_long_inc(&session->stats.rx_seq_discards); 540 l2tp_dbg(session, L2TP_MSG_SEQ, 541 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n", 542 session->name, L2TP_SKB_CB(skb)->ns, 543 L2TP_SKB_CB(skb)->length, session->nr, 544 skb_queue_len(&session->reorder_q)); 545 goto discard; 546 } 547 skb_queue_tail(&session->reorder_q, skb); 548 } 549 550 out: 551 return 0; 552 553 discard: 554 return 1; 555 } 556 557 /* Do receive processing of L2TP data frames. We handle both L2TPv2 558 * and L2TPv3 data frames here. 559 * 560 * L2TPv2 Data Message Header 561 * 562 * 0 1 2 3 563 * 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 1 564 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 565 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) | 566 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 567 * | Tunnel ID | Session ID | 568 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 569 * | Ns (opt) | Nr (opt) | 570 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 571 * | Offset Size (opt) | Offset pad... (opt) 572 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 573 * 574 * Data frames are marked by T=0. All other fields are the same as 575 * those in L2TP control frames. 576 * 577 * L2TPv3 Data Message Header 578 * 579 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 580 * | L2TP Session Header | 581 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 582 * | L2-Specific Sublayer | 583 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 584 * | Tunnel Payload ... 585 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 586 * 587 * L2TPv3 Session Header Over IP 588 * 589 * 0 1 2 3 590 * 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 1 591 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 592 * | Session ID | 593 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 594 * | Cookie (optional, maximum 64 bits)... 595 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 596 * | 597 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 598 * 599 * L2TPv3 L2-Specific Sublayer Format 600 * 601 * 0 1 2 3 602 * 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 1 603 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 604 * |x|S|x|x|x|x|x|x| Sequence Number | 605 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 606 * 607 * Cookie value and sublayer format are negotiated with the peer when 608 * the session is set up. Unlike L2TPv2, we do not need to parse the 609 * packet header to determine if optional fields are present. 610 * 611 * Caller must already have parsed the frame and determined that it is 612 * a data (not control) frame before coming here. Fields up to the 613 * session-id have already been parsed and ptr points to the data 614 * after the session-id. 615 */ 616 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 617 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 618 int length) 619 { 620 struct l2tp_tunnel *tunnel = session->tunnel; 621 int offset; 622 u32 ns, nr; 623 624 /* Parse and check optional cookie */ 625 if (session->peer_cookie_len > 0) { 626 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { 627 l2tp_info(tunnel, L2TP_MSG_DATA, 628 "%s: cookie mismatch (%u/%u). Discarding.\n", 629 tunnel->name, tunnel->tunnel_id, 630 session->session_id); 631 atomic_long_inc(&session->stats.rx_cookie_discards); 632 goto discard; 633 } 634 ptr += session->peer_cookie_len; 635 } 636 637 /* Handle the optional sequence numbers. Sequence numbers are 638 * in different places for L2TPv2 and L2TPv3. 639 * 640 * If we are the LAC, enable/disable sequence numbers under 641 * the control of the LNS. If no sequence numbers present but 642 * we were expecting them, discard frame. 643 */ 644 ns = nr = 0; 645 L2TP_SKB_CB(skb)->has_seq = 0; 646 if (tunnel->version == L2TP_HDR_VER_2) { 647 if (hdrflags & L2TP_HDRFLAG_S) { 648 ns = ntohs(*(__be16 *) ptr); 649 ptr += 2; 650 nr = ntohs(*(__be16 *) ptr); 651 ptr += 2; 652 653 /* Store L2TP info in the skb */ 654 L2TP_SKB_CB(skb)->ns = ns; 655 L2TP_SKB_CB(skb)->has_seq = 1; 656 657 l2tp_dbg(session, L2TP_MSG_SEQ, 658 "%s: recv data ns=%u, nr=%u, session nr=%u\n", 659 session->name, ns, nr, session->nr); 660 } 661 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 662 u32 l2h = ntohl(*(__be32 *) ptr); 663 664 if (l2h & 0x40000000) { 665 ns = l2h & 0x00ffffff; 666 667 /* Store L2TP info in the skb */ 668 L2TP_SKB_CB(skb)->ns = ns; 669 L2TP_SKB_CB(skb)->has_seq = 1; 670 671 l2tp_dbg(session, L2TP_MSG_SEQ, 672 "%s: recv data ns=%u, session nr=%u\n", 673 session->name, ns, session->nr); 674 } 675 ptr += 4; 676 } 677 678 if (L2TP_SKB_CB(skb)->has_seq) { 679 /* Received a packet with sequence numbers. If we're the LNS, 680 * check if we sre sending sequence numbers and if not, 681 * configure it so. 682 */ 683 if ((!session->lns_mode) && (!session->send_seq)) { 684 l2tp_info(session, L2TP_MSG_SEQ, 685 "%s: requested to enable seq numbers by LNS\n", 686 session->name); 687 session->send_seq = 1; 688 l2tp_session_set_header_len(session, tunnel->version); 689 } 690 } else { 691 /* No sequence numbers. 692 * If user has configured mandatory sequence numbers, discard. 693 */ 694 if (session->recv_seq) { 695 l2tp_warn(session, L2TP_MSG_SEQ, 696 "%s: recv data has no seq numbers when required. Discarding.\n", 697 session->name); 698 atomic_long_inc(&session->stats.rx_seq_discards); 699 goto discard; 700 } 701 702 /* If we're the LAC and we're sending sequence numbers, the 703 * LNS has requested that we no longer send sequence numbers. 704 * If we're the LNS and we're sending sequence numbers, the 705 * LAC is broken. Discard the frame. 706 */ 707 if ((!session->lns_mode) && (session->send_seq)) { 708 l2tp_info(session, L2TP_MSG_SEQ, 709 "%s: requested to disable seq numbers by LNS\n", 710 session->name); 711 session->send_seq = 0; 712 l2tp_session_set_header_len(session, tunnel->version); 713 } else if (session->send_seq) { 714 l2tp_warn(session, L2TP_MSG_SEQ, 715 "%s: recv data has no seq numbers when required. Discarding.\n", 716 session->name); 717 atomic_long_inc(&session->stats.rx_seq_discards); 718 goto discard; 719 } 720 } 721 722 /* Session data offset is defined only for L2TPv2 and is 723 * indicated by an optional 16-bit value in the header. 724 */ 725 if (tunnel->version == L2TP_HDR_VER_2) { 726 /* If offset bit set, skip it. */ 727 if (hdrflags & L2TP_HDRFLAG_O) { 728 offset = ntohs(*(__be16 *)ptr); 729 ptr += 2 + offset; 730 } 731 } 732 733 offset = ptr - optr; 734 if (!pskb_may_pull(skb, offset)) 735 goto discard; 736 737 __skb_pull(skb, offset); 738 739 /* Prepare skb for adding to the session's reorder_q. Hold 740 * packets for max reorder_timeout or 1 second if not 741 * reordering. 742 */ 743 L2TP_SKB_CB(skb)->length = length; 744 L2TP_SKB_CB(skb)->expires = jiffies + 745 (session->reorder_timeout ? session->reorder_timeout : HZ); 746 747 /* Add packet to the session's receive queue. Reordering is done here, if 748 * enabled. Saved L2TP protocol info is stored in skb->sb[]. 749 */ 750 if (L2TP_SKB_CB(skb)->has_seq) { 751 if (l2tp_recv_data_seq(session, skb)) 752 goto discard; 753 } else { 754 /* No sequence numbers. Add the skb to the tail of the 755 * reorder queue. This ensures that it will be 756 * delivered after all previous sequenced skbs. 757 */ 758 skb_queue_tail(&session->reorder_q, skb); 759 } 760 761 /* Try to dequeue as many skbs from reorder_q as we can. */ 762 l2tp_recv_dequeue(session); 763 764 return; 765 766 discard: 767 atomic_long_inc(&session->stats.rx_errors); 768 kfree_skb(skb); 769 } 770 EXPORT_SYMBOL(l2tp_recv_common); 771 772 /* Drop skbs from the session's reorder_q 773 */ 774 static int l2tp_session_queue_purge(struct l2tp_session *session) 775 { 776 struct sk_buff *skb = NULL; 777 BUG_ON(!session); 778 BUG_ON(session->magic != L2TP_SESSION_MAGIC); 779 while ((skb = skb_dequeue(&session->reorder_q))) { 780 atomic_long_inc(&session->stats.rx_errors); 781 kfree_skb(skb); 782 } 783 return 0; 784 } 785 786 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame 787 * here. The skb is not on a list when we get here. 788 * Returns 0 if the packet was a data packet and was successfully passed on. 789 * Returns 1 if the packet was not a good data packet and could not be 790 * forwarded. All such packets are passed up to userspace to deal with. 791 */ 792 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb) 793 { 794 struct l2tp_session *session = NULL; 795 unsigned char *ptr, *optr; 796 u16 hdrflags; 797 u32 tunnel_id, session_id; 798 u16 version; 799 int length; 800 801 /* UDP has verifed checksum */ 802 803 /* UDP always verifies the packet length. */ 804 __skb_pull(skb, sizeof(struct udphdr)); 805 806 /* Short packet? */ 807 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX)) { 808 l2tp_info(tunnel, L2TP_MSG_DATA, 809 "%s: recv short packet (len=%d)\n", 810 tunnel->name, skb->len); 811 goto error; 812 } 813 814 /* Trace packet contents, if enabled */ 815 if (tunnel->debug & L2TP_MSG_DATA) { 816 length = min(32u, skb->len); 817 if (!pskb_may_pull(skb, length)) 818 goto error; 819 820 pr_debug("%s: recv\n", tunnel->name); 821 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 822 } 823 824 /* Point to L2TP header */ 825 optr = ptr = skb->data; 826 827 /* Get L2TP header flags */ 828 hdrflags = ntohs(*(__be16 *) ptr); 829 830 /* Check protocol version */ 831 version = hdrflags & L2TP_HDR_VER_MASK; 832 if (version != tunnel->version) { 833 l2tp_info(tunnel, L2TP_MSG_DATA, 834 "%s: recv protocol version mismatch: got %d expected %d\n", 835 tunnel->name, version, tunnel->version); 836 goto error; 837 } 838 839 /* Get length of L2TP packet */ 840 length = skb->len; 841 842 /* If type is control packet, it is handled by userspace. */ 843 if (hdrflags & L2TP_HDRFLAG_T) { 844 l2tp_dbg(tunnel, L2TP_MSG_DATA, 845 "%s: recv control packet, len=%d\n", 846 tunnel->name, length); 847 goto error; 848 } 849 850 /* Skip flags */ 851 ptr += 2; 852 853 if (tunnel->version == L2TP_HDR_VER_2) { 854 /* If length is present, skip it */ 855 if (hdrflags & L2TP_HDRFLAG_L) 856 ptr += 2; 857 858 /* Extract tunnel and session ID */ 859 tunnel_id = ntohs(*(__be16 *) ptr); 860 ptr += 2; 861 session_id = ntohs(*(__be16 *) ptr); 862 ptr += 2; 863 } else { 864 ptr += 2; /* skip reserved bits */ 865 tunnel_id = tunnel->tunnel_id; 866 session_id = ntohl(*(__be32 *) ptr); 867 ptr += 4; 868 } 869 870 /* Find the session context */ 871 session = l2tp_tunnel_get_session(tunnel, session_id); 872 if (!session || !session->recv_skb) { 873 if (session) 874 l2tp_session_dec_refcount(session); 875 876 /* Not found? Pass to userspace to deal with */ 877 l2tp_info(tunnel, L2TP_MSG_DATA, 878 "%s: no session found (%u/%u). Passing up.\n", 879 tunnel->name, tunnel_id, session_id); 880 goto error; 881 } 882 883 if (tunnel->version == L2TP_HDR_VER_3 && 884 l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) 885 goto error; 886 887 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length); 888 l2tp_session_dec_refcount(session); 889 890 return 0; 891 892 error: 893 /* Put UDP header back */ 894 __skb_push(skb, sizeof(struct udphdr)); 895 896 return 1; 897 } 898 899 /* UDP encapsulation receive handler. See net/ipv4/udp.c. 900 * Return codes: 901 * 0 : success. 902 * <0: error 903 * >0: skb should be passed up to userspace as UDP. 904 */ 905 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 906 { 907 struct l2tp_tunnel *tunnel; 908 909 tunnel = rcu_dereference_sk_user_data(sk); 910 if (tunnel == NULL) 911 goto pass_up; 912 913 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n", 914 tunnel->name, skb->len); 915 916 if (l2tp_udp_recv_core(tunnel, skb)) 917 goto pass_up; 918 919 return 0; 920 921 pass_up: 922 return 1; 923 } 924 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 925 926 /************************************************************************ 927 * Transmit handling 928 ***********************************************************************/ 929 930 /* Build an L2TP header for the session into the buffer provided. 931 */ 932 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 933 { 934 struct l2tp_tunnel *tunnel = session->tunnel; 935 __be16 *bufp = buf; 936 __be16 *optr = buf; 937 u16 flags = L2TP_HDR_VER_2; 938 u32 tunnel_id = tunnel->peer_tunnel_id; 939 u32 session_id = session->peer_session_id; 940 941 if (session->send_seq) 942 flags |= L2TP_HDRFLAG_S; 943 944 /* Setup L2TP header. */ 945 *bufp++ = htons(flags); 946 *bufp++ = htons(tunnel_id); 947 *bufp++ = htons(session_id); 948 if (session->send_seq) { 949 *bufp++ = htons(session->ns); 950 *bufp++ = 0; 951 session->ns++; 952 session->ns &= 0xffff; 953 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n", 954 session->name, session->ns); 955 } 956 957 return bufp - optr; 958 } 959 960 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 961 { 962 struct l2tp_tunnel *tunnel = session->tunnel; 963 char *bufp = buf; 964 char *optr = bufp; 965 966 /* Setup L2TP header. The header differs slightly for UDP and 967 * IP encapsulations. For UDP, there is 4 bytes of flags. 968 */ 969 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 970 u16 flags = L2TP_HDR_VER_3; 971 *((__be16 *) bufp) = htons(flags); 972 bufp += 2; 973 *((__be16 *) bufp) = 0; 974 bufp += 2; 975 } 976 977 *((__be32 *) bufp) = htonl(session->peer_session_id); 978 bufp += 4; 979 if (session->cookie_len) { 980 memcpy(bufp, &session->cookie[0], session->cookie_len); 981 bufp += session->cookie_len; 982 } 983 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 984 u32 l2h = 0; 985 986 if (session->send_seq) { 987 l2h = 0x40000000 | session->ns; 988 session->ns++; 989 session->ns &= 0xffffff; 990 l2tp_dbg(session, L2TP_MSG_SEQ, 991 "%s: updated ns to %u\n", 992 session->name, session->ns); 993 } 994 995 *((__be32 *)bufp) = htonl(l2h); 996 bufp += 4; 997 } 998 999 return bufp - optr; 1000 } 1001 1002 static void l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, 1003 struct flowi *fl, size_t data_len) 1004 { 1005 struct l2tp_tunnel *tunnel = session->tunnel; 1006 unsigned int len = skb->len; 1007 int error; 1008 1009 /* Debug */ 1010 if (session->send_seq) 1011 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes, ns=%u\n", 1012 session->name, data_len, session->ns - 1); 1013 else 1014 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes\n", 1015 session->name, data_len); 1016 1017 if (session->debug & L2TP_MSG_DATA) { 1018 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1019 unsigned char *datap = skb->data + uhlen; 1020 1021 pr_debug("%s: xmit\n", session->name); 1022 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, 1023 datap, min_t(size_t, 32, len - uhlen)); 1024 } 1025 1026 /* Queue the packet to IP for output */ 1027 skb->ignore_df = 1; 1028 #if IS_ENABLED(CONFIG_IPV6) 1029 if (l2tp_sk_is_v6(tunnel->sock)) 1030 error = inet6_csk_xmit(tunnel->sock, skb, NULL); 1031 else 1032 #endif 1033 error = ip_queue_xmit(tunnel->sock, skb, fl); 1034 1035 /* Update stats */ 1036 if (error >= 0) { 1037 atomic_long_inc(&tunnel->stats.tx_packets); 1038 atomic_long_add(len, &tunnel->stats.tx_bytes); 1039 atomic_long_inc(&session->stats.tx_packets); 1040 atomic_long_add(len, &session->stats.tx_bytes); 1041 } else { 1042 atomic_long_inc(&tunnel->stats.tx_errors); 1043 atomic_long_inc(&session->stats.tx_errors); 1044 } 1045 } 1046 1047 /* If caller requires the skb to have a ppp header, the header must be 1048 * inserted in the skb data before calling this function. 1049 */ 1050 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len) 1051 { 1052 int data_len = skb->len; 1053 struct l2tp_tunnel *tunnel = session->tunnel; 1054 struct sock *sk = tunnel->sock; 1055 struct flowi *fl; 1056 struct udphdr *uh; 1057 struct inet_sock *inet; 1058 int headroom; 1059 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1060 int udp_len; 1061 int ret = NET_XMIT_SUCCESS; 1062 1063 /* Check that there's enough headroom in the skb to insert IP, 1064 * UDP and L2TP headers. If not enough, expand it to 1065 * make room. Adjust truesize. 1066 */ 1067 headroom = NET_SKB_PAD + sizeof(struct iphdr) + 1068 uhlen + hdr_len; 1069 if (skb_cow_head(skb, headroom)) { 1070 kfree_skb(skb); 1071 return NET_XMIT_DROP; 1072 } 1073 1074 /* Setup L2TP header */ 1075 session->build_header(session, __skb_push(skb, hdr_len)); 1076 1077 /* Reset skb netfilter state */ 1078 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1079 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | 1080 IPSKB_REROUTED); 1081 nf_reset_ct(skb); 1082 1083 bh_lock_sock(sk); 1084 if (sock_owned_by_user(sk)) { 1085 kfree_skb(skb); 1086 ret = NET_XMIT_DROP; 1087 goto out_unlock; 1088 } 1089 1090 /* The user-space may change the connection status for the user-space 1091 * provided socket at run time: we must check it under the socket lock 1092 */ 1093 if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) { 1094 kfree_skb(skb); 1095 ret = NET_XMIT_DROP; 1096 goto out_unlock; 1097 } 1098 1099 /* Get routing info from the tunnel socket */ 1100 skb_dst_drop(skb); 1101 skb_dst_set(skb, sk_dst_check(sk, 0)); 1102 1103 inet = inet_sk(sk); 1104 fl = &inet->cork.fl; 1105 switch (tunnel->encap) { 1106 case L2TP_ENCAPTYPE_UDP: 1107 /* Setup UDP header */ 1108 __skb_push(skb, sizeof(*uh)); 1109 skb_reset_transport_header(skb); 1110 uh = udp_hdr(skb); 1111 uh->source = inet->inet_sport; 1112 uh->dest = inet->inet_dport; 1113 udp_len = uhlen + hdr_len + data_len; 1114 uh->len = htons(udp_len); 1115 1116 /* Calculate UDP checksum if configured to do so */ 1117 #if IS_ENABLED(CONFIG_IPV6) 1118 if (l2tp_sk_is_v6(sk)) 1119 udp6_set_csum(udp_get_no_check6_tx(sk), 1120 skb, &inet6_sk(sk)->saddr, 1121 &sk->sk_v6_daddr, udp_len); 1122 else 1123 #endif 1124 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr, 1125 inet->inet_daddr, udp_len); 1126 break; 1127 1128 case L2TP_ENCAPTYPE_IP: 1129 break; 1130 } 1131 1132 l2tp_xmit_core(session, skb, fl, data_len); 1133 out_unlock: 1134 bh_unlock_sock(sk); 1135 1136 return ret; 1137 } 1138 EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1139 1140 /***************************************************************************** 1141 * Tinnel and session create/destroy. 1142 *****************************************************************************/ 1143 1144 /* Tunnel socket destruct hook. 1145 * The tunnel context is deleted only when all session sockets have been 1146 * closed. 1147 */ 1148 static void l2tp_tunnel_destruct(struct sock *sk) 1149 { 1150 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1151 1152 if (tunnel == NULL) 1153 goto end; 1154 1155 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name); 1156 1157 /* Disable udp encapsulation */ 1158 switch (tunnel->encap) { 1159 case L2TP_ENCAPTYPE_UDP: 1160 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1161 (udp_sk(sk))->encap_type = 0; 1162 (udp_sk(sk))->encap_rcv = NULL; 1163 (udp_sk(sk))->encap_destroy = NULL; 1164 break; 1165 case L2TP_ENCAPTYPE_IP: 1166 break; 1167 } 1168 1169 /* Remove hooks into tunnel socket */ 1170 sk->sk_destruct = tunnel->old_sk_destruct; 1171 sk->sk_user_data = NULL; 1172 1173 /* Call the original destructor */ 1174 if (sk->sk_destruct) 1175 (*sk->sk_destruct)(sk); 1176 1177 kfree_rcu(tunnel, rcu); 1178 end: 1179 return; 1180 } 1181 1182 /* When the tunnel is closed, all the attached sessions need to go too. 1183 */ 1184 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1185 { 1186 int hash; 1187 struct hlist_node *walk; 1188 struct hlist_node *tmp; 1189 struct l2tp_session *session; 1190 1191 BUG_ON(tunnel == NULL); 1192 1193 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n", 1194 tunnel->name); 1195 1196 write_lock_bh(&tunnel->hlist_lock); 1197 tunnel->acpt_newsess = false; 1198 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1199 again: 1200 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) { 1201 session = hlist_entry(walk, struct l2tp_session, hlist); 1202 1203 l2tp_info(session, L2TP_MSG_CONTROL, 1204 "%s: closing session\n", session->name); 1205 1206 hlist_del_init(&session->hlist); 1207 1208 if (test_and_set_bit(0, &session->dead)) 1209 goto again; 1210 1211 write_unlock_bh(&tunnel->hlist_lock); 1212 1213 __l2tp_session_unhash(session); 1214 l2tp_session_queue_purge(session); 1215 1216 if (session->session_close != NULL) 1217 (*session->session_close)(session); 1218 1219 l2tp_session_dec_refcount(session); 1220 1221 write_lock_bh(&tunnel->hlist_lock); 1222 1223 /* Now restart from the beginning of this hash 1224 * chain. We always remove a session from the 1225 * list so we are guaranteed to make forward 1226 * progress. 1227 */ 1228 goto again; 1229 } 1230 } 1231 write_unlock_bh(&tunnel->hlist_lock); 1232 } 1233 1234 /* Tunnel socket destroy hook for UDP encapsulation */ 1235 static void l2tp_udp_encap_destroy(struct sock *sk) 1236 { 1237 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1238 1239 if (tunnel) 1240 l2tp_tunnel_delete(tunnel); 1241 } 1242 1243 /* Workqueue tunnel deletion function */ 1244 static void l2tp_tunnel_del_work(struct work_struct *work) 1245 { 1246 struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, 1247 del_work); 1248 struct sock *sk = tunnel->sock; 1249 struct socket *sock = sk->sk_socket; 1250 struct l2tp_net *pn; 1251 1252 l2tp_tunnel_closeall(tunnel); 1253 1254 /* If the tunnel socket was created within the kernel, use 1255 * the sk API to release it here. 1256 */ 1257 if (tunnel->fd < 0) { 1258 if (sock) { 1259 kernel_sock_shutdown(sock, SHUT_RDWR); 1260 sock_release(sock); 1261 } 1262 } 1263 1264 /* Remove the tunnel struct from the tunnel list */ 1265 pn = l2tp_pernet(tunnel->l2tp_net); 1266 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1267 list_del_rcu(&tunnel->list); 1268 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1269 1270 /* drop initial ref */ 1271 l2tp_tunnel_dec_refcount(tunnel); 1272 1273 /* drop workqueue ref */ 1274 l2tp_tunnel_dec_refcount(tunnel); 1275 } 1276 1277 /* Create a socket for the tunnel, if one isn't set up by 1278 * userspace. This is used for static tunnels where there is no 1279 * managing L2TP daemon. 1280 * 1281 * Since we don't want these sockets to keep a namespace alive by 1282 * themselves, we drop the socket's namespace refcount after creation. 1283 * These sockets are freed when the namespace exits using the pernet 1284 * exit hook. 1285 */ 1286 static int l2tp_tunnel_sock_create(struct net *net, 1287 u32 tunnel_id, 1288 u32 peer_tunnel_id, 1289 struct l2tp_tunnel_cfg *cfg, 1290 struct socket **sockp) 1291 { 1292 int err = -EINVAL; 1293 struct socket *sock = NULL; 1294 struct udp_port_cfg udp_conf; 1295 1296 switch (cfg->encap) { 1297 case L2TP_ENCAPTYPE_UDP: 1298 memset(&udp_conf, 0, sizeof(udp_conf)); 1299 1300 #if IS_ENABLED(CONFIG_IPV6) 1301 if (cfg->local_ip6 && cfg->peer_ip6) { 1302 udp_conf.family = AF_INET6; 1303 memcpy(&udp_conf.local_ip6, cfg->local_ip6, 1304 sizeof(udp_conf.local_ip6)); 1305 memcpy(&udp_conf.peer_ip6, cfg->peer_ip6, 1306 sizeof(udp_conf.peer_ip6)); 1307 udp_conf.use_udp6_tx_checksums = 1308 ! cfg->udp6_zero_tx_checksums; 1309 udp_conf.use_udp6_rx_checksums = 1310 ! cfg->udp6_zero_rx_checksums; 1311 } else 1312 #endif 1313 { 1314 udp_conf.family = AF_INET; 1315 udp_conf.local_ip = cfg->local_ip; 1316 udp_conf.peer_ip = cfg->peer_ip; 1317 udp_conf.use_udp_checksums = cfg->use_udp_checksums; 1318 } 1319 1320 udp_conf.local_udp_port = htons(cfg->local_udp_port); 1321 udp_conf.peer_udp_port = htons(cfg->peer_udp_port); 1322 1323 err = udp_sock_create(net, &udp_conf, &sock); 1324 if (err < 0) 1325 goto out; 1326 1327 break; 1328 1329 case L2TP_ENCAPTYPE_IP: 1330 #if IS_ENABLED(CONFIG_IPV6) 1331 if (cfg->local_ip6 && cfg->peer_ip6) { 1332 struct sockaddr_l2tpip6 ip6_addr = {0}; 1333 1334 err = sock_create_kern(net, AF_INET6, SOCK_DGRAM, 1335 IPPROTO_L2TP, &sock); 1336 if (err < 0) 1337 goto out; 1338 1339 ip6_addr.l2tp_family = AF_INET6; 1340 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6, 1341 sizeof(ip6_addr.l2tp_addr)); 1342 ip6_addr.l2tp_conn_id = tunnel_id; 1343 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr, 1344 sizeof(ip6_addr)); 1345 if (err < 0) 1346 goto out; 1347 1348 ip6_addr.l2tp_family = AF_INET6; 1349 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6, 1350 sizeof(ip6_addr.l2tp_addr)); 1351 ip6_addr.l2tp_conn_id = peer_tunnel_id; 1352 err = kernel_connect(sock, 1353 (struct sockaddr *) &ip6_addr, 1354 sizeof(ip6_addr), 0); 1355 if (err < 0) 1356 goto out; 1357 } else 1358 #endif 1359 { 1360 struct sockaddr_l2tpip ip_addr = {0}; 1361 1362 err = sock_create_kern(net, AF_INET, SOCK_DGRAM, 1363 IPPROTO_L2TP, &sock); 1364 if (err < 0) 1365 goto out; 1366 1367 ip_addr.l2tp_family = AF_INET; 1368 ip_addr.l2tp_addr = cfg->local_ip; 1369 ip_addr.l2tp_conn_id = tunnel_id; 1370 err = kernel_bind(sock, (struct sockaddr *) &ip_addr, 1371 sizeof(ip_addr)); 1372 if (err < 0) 1373 goto out; 1374 1375 ip_addr.l2tp_family = AF_INET; 1376 ip_addr.l2tp_addr = cfg->peer_ip; 1377 ip_addr.l2tp_conn_id = peer_tunnel_id; 1378 err = kernel_connect(sock, (struct sockaddr *) &ip_addr, 1379 sizeof(ip_addr), 0); 1380 if (err < 0) 1381 goto out; 1382 } 1383 break; 1384 1385 default: 1386 goto out; 1387 } 1388 1389 out: 1390 *sockp = sock; 1391 if ((err < 0) && sock) { 1392 kernel_sock_shutdown(sock, SHUT_RDWR); 1393 sock_release(sock); 1394 *sockp = NULL; 1395 } 1396 1397 return err; 1398 } 1399 1400 static struct lock_class_key l2tp_socket_class; 1401 1402 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) 1403 { 1404 struct l2tp_tunnel *tunnel = NULL; 1405 int err; 1406 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1407 1408 if (cfg != NULL) 1409 encap = cfg->encap; 1410 1411 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL); 1412 if (tunnel == NULL) { 1413 err = -ENOMEM; 1414 goto err; 1415 } 1416 1417 tunnel->version = version; 1418 tunnel->tunnel_id = tunnel_id; 1419 tunnel->peer_tunnel_id = peer_tunnel_id; 1420 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS; 1421 1422 tunnel->magic = L2TP_TUNNEL_MAGIC; 1423 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1424 rwlock_init(&tunnel->hlist_lock); 1425 tunnel->acpt_newsess = true; 1426 1427 if (cfg != NULL) 1428 tunnel->debug = cfg->debug; 1429 1430 tunnel->encap = encap; 1431 1432 refcount_set(&tunnel->ref_count, 1); 1433 tunnel->fd = fd; 1434 1435 /* Init delete workqueue struct */ 1436 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); 1437 1438 INIT_LIST_HEAD(&tunnel->list); 1439 1440 err = 0; 1441 err: 1442 if (tunnelp) 1443 *tunnelp = tunnel; 1444 1445 return err; 1446 } 1447 EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1448 1449 static int l2tp_validate_socket(const struct sock *sk, const struct net *net, 1450 enum l2tp_encap_type encap) 1451 { 1452 if (!net_eq(sock_net(sk), net)) 1453 return -EINVAL; 1454 1455 if (sk->sk_type != SOCK_DGRAM) 1456 return -EPROTONOSUPPORT; 1457 1458 if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) || 1459 (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP)) 1460 return -EPROTONOSUPPORT; 1461 1462 if (sk->sk_user_data) 1463 return -EBUSY; 1464 1465 return 0; 1466 } 1467 1468 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 1469 struct l2tp_tunnel_cfg *cfg) 1470 { 1471 struct l2tp_tunnel *tunnel_walk; 1472 struct l2tp_net *pn; 1473 struct socket *sock; 1474 struct sock *sk; 1475 int ret; 1476 1477 if (tunnel->fd < 0) { 1478 ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id, 1479 tunnel->peer_tunnel_id, cfg, 1480 &sock); 1481 if (ret < 0) 1482 goto err; 1483 } else { 1484 sock = sockfd_lookup(tunnel->fd, &ret); 1485 if (!sock) 1486 goto err; 1487 1488 ret = l2tp_validate_socket(sock->sk, net, tunnel->encap); 1489 if (ret < 0) 1490 goto err_sock; 1491 } 1492 1493 tunnel->l2tp_net = net; 1494 pn = l2tp_pernet(net); 1495 1496 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1497 list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) { 1498 if (tunnel_walk->tunnel_id == tunnel->tunnel_id) { 1499 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1500 1501 ret = -EEXIST; 1502 goto err_sock; 1503 } 1504 } 1505 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); 1506 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1507 1508 sk = sock->sk; 1509 sock_hold(sk); 1510 tunnel->sock = sk; 1511 1512 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1513 struct udp_tunnel_sock_cfg udp_cfg = { 1514 .sk_user_data = tunnel, 1515 .encap_type = UDP_ENCAP_L2TPINUDP, 1516 .encap_rcv = l2tp_udp_encap_recv, 1517 .encap_destroy = l2tp_udp_encap_destroy, 1518 }; 1519 1520 setup_udp_tunnel_sock(net, sock, &udp_cfg); 1521 } else { 1522 sk->sk_user_data = tunnel; 1523 } 1524 1525 tunnel->old_sk_destruct = sk->sk_destruct; 1526 sk->sk_destruct = &l2tp_tunnel_destruct; 1527 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, 1528 "l2tp_sock"); 1529 sk->sk_allocation = GFP_ATOMIC; 1530 1531 if (tunnel->fd >= 0) 1532 sockfd_put(sock); 1533 1534 return 0; 1535 1536 err_sock: 1537 if (tunnel->fd < 0) 1538 sock_release(sock); 1539 else 1540 sockfd_put(sock); 1541 err: 1542 return ret; 1543 } 1544 EXPORT_SYMBOL_GPL(l2tp_tunnel_register); 1545 1546 /* This function is used by the netlink TUNNEL_DELETE command. 1547 */ 1548 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1549 { 1550 if (!test_and_set_bit(0, &tunnel->dead)) { 1551 l2tp_tunnel_inc_refcount(tunnel); 1552 queue_work(l2tp_wq, &tunnel->del_work); 1553 } 1554 } 1555 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1556 1557 /* Really kill the session. 1558 */ 1559 void l2tp_session_free(struct l2tp_session *session) 1560 { 1561 struct l2tp_tunnel *tunnel = session->tunnel; 1562 1563 BUG_ON(refcount_read(&session->ref_count) != 0); 1564 1565 if (tunnel) { 1566 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC); 1567 l2tp_tunnel_dec_refcount(tunnel); 1568 } 1569 1570 kfree(session); 1571 } 1572 EXPORT_SYMBOL_GPL(l2tp_session_free); 1573 1574 /* Remove an l2tp session from l2tp_core's hash lists. 1575 * Provides a tidyup interface for pseudowire code which can't just route all 1576 * shutdown via. l2tp_session_delete and a pseudowire-specific session_close 1577 * callback. 1578 */ 1579 void __l2tp_session_unhash(struct l2tp_session *session) 1580 { 1581 struct l2tp_tunnel *tunnel = session->tunnel; 1582 1583 /* Remove the session from core hashes */ 1584 if (tunnel) { 1585 /* Remove from the per-tunnel hash */ 1586 write_lock_bh(&tunnel->hlist_lock); 1587 hlist_del_init(&session->hlist); 1588 write_unlock_bh(&tunnel->hlist_lock); 1589 1590 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1591 if (tunnel->version != L2TP_HDR_VER_2) { 1592 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1593 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1594 hlist_del_init_rcu(&session->global_hlist); 1595 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1596 synchronize_rcu(); 1597 } 1598 } 1599 } 1600 EXPORT_SYMBOL_GPL(__l2tp_session_unhash); 1601 1602 /* This function is used by the netlink SESSION_DELETE command and by 1603 pseudowire modules. 1604 */ 1605 int l2tp_session_delete(struct l2tp_session *session) 1606 { 1607 if (test_and_set_bit(0, &session->dead)) 1608 return 0; 1609 1610 __l2tp_session_unhash(session); 1611 l2tp_session_queue_purge(session); 1612 if (session->session_close != NULL) 1613 (*session->session_close)(session); 1614 1615 l2tp_session_dec_refcount(session); 1616 1617 return 0; 1618 } 1619 EXPORT_SYMBOL_GPL(l2tp_session_delete); 1620 1621 /* We come here whenever a session's send_seq, cookie_len or 1622 * l2specific_type parameters are set. 1623 */ 1624 void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1625 { 1626 if (version == L2TP_HDR_VER_2) { 1627 session->hdr_len = 6; 1628 if (session->send_seq) 1629 session->hdr_len += 4; 1630 } else { 1631 session->hdr_len = 4 + session->cookie_len; 1632 session->hdr_len += l2tp_get_l2specific_len(session); 1633 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1634 session->hdr_len += 4; 1635 } 1636 1637 } 1638 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1639 1640 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) 1641 { 1642 struct l2tp_session *session; 1643 1644 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL); 1645 if (session != NULL) { 1646 session->magic = L2TP_SESSION_MAGIC; 1647 session->tunnel = tunnel; 1648 1649 session->session_id = session_id; 1650 session->peer_session_id = peer_session_id; 1651 session->nr = 0; 1652 if (tunnel->version == L2TP_HDR_VER_2) 1653 session->nr_max = 0xffff; 1654 else 1655 session->nr_max = 0xffffff; 1656 session->nr_window_size = session->nr_max / 2; 1657 session->nr_oos_count_max = 4; 1658 1659 /* Use NR of first received packet */ 1660 session->reorder_skip = 1; 1661 1662 sprintf(&session->name[0], "sess %u/%u", 1663 tunnel->tunnel_id, session->session_id); 1664 1665 skb_queue_head_init(&session->reorder_q); 1666 1667 INIT_HLIST_NODE(&session->hlist); 1668 INIT_HLIST_NODE(&session->global_hlist); 1669 1670 /* Inherit debug options from tunnel */ 1671 session->debug = tunnel->debug; 1672 1673 if (cfg) { 1674 session->pwtype = cfg->pw_type; 1675 session->debug = cfg->debug; 1676 session->send_seq = cfg->send_seq; 1677 session->recv_seq = cfg->recv_seq; 1678 session->lns_mode = cfg->lns_mode; 1679 session->reorder_timeout = cfg->reorder_timeout; 1680 session->l2specific_type = cfg->l2specific_type; 1681 session->cookie_len = cfg->cookie_len; 1682 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1683 session->peer_cookie_len = cfg->peer_cookie_len; 1684 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1685 } 1686 1687 if (tunnel->version == L2TP_HDR_VER_2) 1688 session->build_header = l2tp_build_l2tpv2_header; 1689 else 1690 session->build_header = l2tp_build_l2tpv3_header; 1691 1692 l2tp_session_set_header_len(session, tunnel->version); 1693 1694 refcount_set(&session->ref_count, 1); 1695 1696 return session; 1697 } 1698 1699 return ERR_PTR(-ENOMEM); 1700 } 1701 EXPORT_SYMBOL_GPL(l2tp_session_create); 1702 1703 /***************************************************************************** 1704 * Init and cleanup 1705 *****************************************************************************/ 1706 1707 static __net_init int l2tp_init_net(struct net *net) 1708 { 1709 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1710 int hash; 1711 1712 INIT_LIST_HEAD(&pn->l2tp_tunnel_list); 1713 spin_lock_init(&pn->l2tp_tunnel_list_lock); 1714 1715 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1716 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1717 1718 spin_lock_init(&pn->l2tp_session_hlist_lock); 1719 1720 return 0; 1721 } 1722 1723 static __net_exit void l2tp_exit_net(struct net *net) 1724 { 1725 struct l2tp_net *pn = l2tp_pernet(net); 1726 struct l2tp_tunnel *tunnel = NULL; 1727 int hash; 1728 1729 rcu_read_lock_bh(); 1730 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 1731 l2tp_tunnel_delete(tunnel); 1732 } 1733 rcu_read_unlock_bh(); 1734 1735 if (l2tp_wq) 1736 flush_workqueue(l2tp_wq); 1737 rcu_barrier(); 1738 1739 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1740 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); 1741 } 1742 1743 static struct pernet_operations l2tp_net_ops = { 1744 .init = l2tp_init_net, 1745 .exit = l2tp_exit_net, 1746 .id = &l2tp_net_id, 1747 .size = sizeof(struct l2tp_net), 1748 }; 1749 1750 static int __init l2tp_init(void) 1751 { 1752 int rc = 0; 1753 1754 rc = register_pernet_device(&l2tp_net_ops); 1755 if (rc) 1756 goto out; 1757 1758 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1759 if (!l2tp_wq) { 1760 pr_err("alloc_workqueue failed\n"); 1761 unregister_pernet_device(&l2tp_net_ops); 1762 rc = -ENOMEM; 1763 goto out; 1764 } 1765 1766 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 1767 1768 out: 1769 return rc; 1770 } 1771 1772 static void __exit l2tp_exit(void) 1773 { 1774 unregister_pernet_device(&l2tp_net_ops); 1775 if (l2tp_wq) { 1776 destroy_workqueue(l2tp_wq); 1777 l2tp_wq = NULL; 1778 } 1779 } 1780 1781 module_init(l2tp_init); 1782 module_exit(l2tp_exit); 1783 1784 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1785 MODULE_DESCRIPTION("L2TP core"); 1786 MODULE_LICENSE("GPL"); 1787 MODULE_VERSION(L2TP_DRV_VERSION); 1788