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 return net_generic(net, l2tp_net_id); 126 } 127 128 /* Session hash global list for L2TPv3. 129 * The session_id SHOULD be random according to RFC3931, but several 130 * L2TP implementations use incrementing session_ids. So we do a real 131 * hash on the session_id, rather than a simple bitmask. 132 */ 133 static inline struct hlist_head * 134 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id) 135 { 136 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)]; 137 138 } 139 140 /* Session hash list. 141 * The session_id SHOULD be random according to RFC2661, but several 142 * L2TP implementations (Cisco and Microsoft) use incrementing 143 * session_ids. So we do a real hash on the session_id, rather than a 144 * simple bitmask. 145 */ 146 static inline struct hlist_head * 147 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id) 148 { 149 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)]; 150 } 151 152 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) 153 { 154 sock_put(tunnel->sock); 155 /* the tunnel is freed in the socket destructor */ 156 } 157 EXPORT_SYMBOL(l2tp_tunnel_free); 158 159 /* Lookup a tunnel. A new reference is held on the returned tunnel. */ 160 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) 161 { 162 const struct l2tp_net *pn = l2tp_pernet(net); 163 struct l2tp_tunnel *tunnel; 164 165 rcu_read_lock_bh(); 166 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 167 if (tunnel->tunnel_id == tunnel_id && 168 refcount_inc_not_zero(&tunnel->ref_count)) { 169 rcu_read_unlock_bh(); 170 171 return tunnel; 172 } 173 } 174 rcu_read_unlock_bh(); 175 176 return NULL; 177 } 178 EXPORT_SYMBOL_GPL(l2tp_tunnel_get); 179 180 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) 181 { 182 const struct l2tp_net *pn = l2tp_pernet(net); 183 struct l2tp_tunnel *tunnel; 184 int count = 0; 185 186 rcu_read_lock_bh(); 187 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 188 if (++count > nth && 189 refcount_inc_not_zero(&tunnel->ref_count)) { 190 rcu_read_unlock_bh(); 191 return tunnel; 192 } 193 } 194 rcu_read_unlock_bh(); 195 196 return NULL; 197 } 198 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth); 199 200 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel, 201 u32 session_id) 202 { 203 struct hlist_head *session_list; 204 struct l2tp_session *session; 205 206 session_list = l2tp_session_id_hash(tunnel, session_id); 207 208 read_lock_bh(&tunnel->hlist_lock); 209 hlist_for_each_entry(session, session_list, hlist) 210 if (session->session_id == session_id) { 211 l2tp_session_inc_refcount(session); 212 read_unlock_bh(&tunnel->hlist_lock); 213 214 return session; 215 } 216 read_unlock_bh(&tunnel->hlist_lock); 217 218 return NULL; 219 } 220 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_session); 221 222 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id) 223 { 224 struct hlist_head *session_list; 225 struct l2tp_session *session; 226 227 session_list = l2tp_session_id_hash_2(l2tp_pernet(net), session_id); 228 229 rcu_read_lock_bh(); 230 hlist_for_each_entry_rcu(session, session_list, global_hlist) 231 if (session->session_id == session_id) { 232 l2tp_session_inc_refcount(session); 233 rcu_read_unlock_bh(); 234 235 return session; 236 } 237 rcu_read_unlock_bh(); 238 239 return NULL; 240 } 241 EXPORT_SYMBOL_GPL(l2tp_session_get); 242 243 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth) 244 { 245 int hash; 246 struct l2tp_session *session; 247 int count = 0; 248 249 read_lock_bh(&tunnel->hlist_lock); 250 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 251 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) { 252 if (++count > nth) { 253 l2tp_session_inc_refcount(session); 254 read_unlock_bh(&tunnel->hlist_lock); 255 return session; 256 } 257 } 258 } 259 260 read_unlock_bh(&tunnel->hlist_lock); 261 262 return NULL; 263 } 264 EXPORT_SYMBOL_GPL(l2tp_session_get_nth); 265 266 /* Lookup a session by interface name. 267 * This is very inefficient but is only used by management interfaces. 268 */ 269 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 270 const char *ifname) 271 { 272 struct l2tp_net *pn = l2tp_pernet(net); 273 int hash; 274 struct l2tp_session *session; 275 276 rcu_read_lock_bh(); 277 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { 278 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) { 279 if (!strcmp(session->ifname, ifname)) { 280 l2tp_session_inc_refcount(session); 281 rcu_read_unlock_bh(); 282 283 return session; 284 } 285 } 286 } 287 288 rcu_read_unlock_bh(); 289 290 return NULL; 291 } 292 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); 293 294 int l2tp_session_register(struct l2tp_session *session, 295 struct l2tp_tunnel *tunnel) 296 { 297 struct l2tp_session *session_walk; 298 struct hlist_head *g_head; 299 struct hlist_head *head; 300 struct l2tp_net *pn; 301 int err; 302 303 head = l2tp_session_id_hash(tunnel, session->session_id); 304 305 write_lock_bh(&tunnel->hlist_lock); 306 if (!tunnel->acpt_newsess) { 307 err = -ENODEV; 308 goto err_tlock; 309 } 310 311 hlist_for_each_entry(session_walk, head, hlist) 312 if (session_walk->session_id == session->session_id) { 313 err = -EEXIST; 314 goto err_tlock; 315 } 316 317 if (tunnel->version == L2TP_HDR_VER_3) { 318 pn = l2tp_pernet(tunnel->l2tp_net); 319 g_head = l2tp_session_id_hash_2(pn, session->session_id); 320 321 spin_lock_bh(&pn->l2tp_session_hlist_lock); 322 323 /* IP encap expects session IDs to be globally unique, while 324 * UDP encap doesn't. 325 */ 326 hlist_for_each_entry(session_walk, g_head, global_hlist) 327 if (session_walk->session_id == session->session_id && 328 (session_walk->tunnel->encap == L2TP_ENCAPTYPE_IP || 329 tunnel->encap == L2TP_ENCAPTYPE_IP)) { 330 err = -EEXIST; 331 goto err_tlock_pnlock; 332 } 333 334 l2tp_tunnel_inc_refcount(tunnel); 335 hlist_add_head_rcu(&session->global_hlist, g_head); 336 337 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 338 } else { 339 l2tp_tunnel_inc_refcount(tunnel); 340 } 341 342 hlist_add_head(&session->hlist, head); 343 write_unlock_bh(&tunnel->hlist_lock); 344 345 return 0; 346 347 err_tlock_pnlock: 348 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 349 err_tlock: 350 write_unlock_bh(&tunnel->hlist_lock); 351 352 return err; 353 } 354 EXPORT_SYMBOL_GPL(l2tp_session_register); 355 356 /***************************************************************************** 357 * Receive data handling 358 *****************************************************************************/ 359 360 /* Queue a skb in order. We come here only if the skb has an L2TP sequence 361 * number. 362 */ 363 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb) 364 { 365 struct sk_buff *skbp; 366 struct sk_buff *tmp; 367 u32 ns = L2TP_SKB_CB(skb)->ns; 368 369 spin_lock_bh(&session->reorder_q.lock); 370 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) { 371 if (L2TP_SKB_CB(skbp)->ns > ns) { 372 __skb_queue_before(&session->reorder_q, skbp, skb); 373 l2tp_dbg(session, L2TP_MSG_SEQ, 374 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n", 375 session->name, ns, L2TP_SKB_CB(skbp)->ns, 376 skb_queue_len(&session->reorder_q)); 377 atomic_long_inc(&session->stats.rx_oos_packets); 378 goto out; 379 } 380 } 381 382 __skb_queue_tail(&session->reorder_q, skb); 383 384 out: 385 spin_unlock_bh(&session->reorder_q.lock); 386 } 387 388 /* Dequeue a single skb. 389 */ 390 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb) 391 { 392 struct l2tp_tunnel *tunnel = session->tunnel; 393 int length = L2TP_SKB_CB(skb)->length; 394 395 /* We're about to requeue the skb, so return resources 396 * to its current owner (a socket receive buffer). 397 */ 398 skb_orphan(skb); 399 400 atomic_long_inc(&tunnel->stats.rx_packets); 401 atomic_long_add(length, &tunnel->stats.rx_bytes); 402 atomic_long_inc(&session->stats.rx_packets); 403 atomic_long_add(length, &session->stats.rx_bytes); 404 405 if (L2TP_SKB_CB(skb)->has_seq) { 406 /* Bump our Nr */ 407 session->nr++; 408 session->nr &= session->nr_max; 409 410 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n", 411 session->name, session->nr); 412 } 413 414 /* call private receive handler */ 415 if (session->recv_skb != NULL) 416 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); 417 else 418 kfree_skb(skb); 419 } 420 421 /* Dequeue skbs from the session's reorder_q, subject to packet order. 422 * Skbs that have been in the queue for too long are simply discarded. 423 */ 424 static void l2tp_recv_dequeue(struct l2tp_session *session) 425 { 426 struct sk_buff *skb; 427 struct sk_buff *tmp; 428 429 /* If the pkt at the head of the queue has the nr that we 430 * expect to send up next, dequeue it and any other 431 * in-sequence packets behind it. 432 */ 433 start: 434 spin_lock_bh(&session->reorder_q.lock); 435 skb_queue_walk_safe(&session->reorder_q, skb, tmp) { 436 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) { 437 atomic_long_inc(&session->stats.rx_seq_discards); 438 atomic_long_inc(&session->stats.rx_errors); 439 l2tp_dbg(session, L2TP_MSG_SEQ, 440 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n", 441 session->name, L2TP_SKB_CB(skb)->ns, 442 L2TP_SKB_CB(skb)->length, session->nr, 443 skb_queue_len(&session->reorder_q)); 444 session->reorder_skip = 1; 445 __skb_unlink(skb, &session->reorder_q); 446 kfree_skb(skb); 447 continue; 448 } 449 450 if (L2TP_SKB_CB(skb)->has_seq) { 451 if (session->reorder_skip) { 452 l2tp_dbg(session, L2TP_MSG_SEQ, 453 "%s: advancing nr to next pkt: %u -> %u", 454 session->name, session->nr, 455 L2TP_SKB_CB(skb)->ns); 456 session->reorder_skip = 0; 457 session->nr = L2TP_SKB_CB(skb)->ns; 458 } 459 if (L2TP_SKB_CB(skb)->ns != session->nr) { 460 l2tp_dbg(session, L2TP_MSG_SEQ, 461 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n", 462 session->name, L2TP_SKB_CB(skb)->ns, 463 L2TP_SKB_CB(skb)->length, session->nr, 464 skb_queue_len(&session->reorder_q)); 465 goto out; 466 } 467 } 468 __skb_unlink(skb, &session->reorder_q); 469 470 /* Process the skb. We release the queue lock while we 471 * do so to let other contexts process the queue. 472 */ 473 spin_unlock_bh(&session->reorder_q.lock); 474 l2tp_recv_dequeue_skb(session, skb); 475 goto start; 476 } 477 478 out: 479 spin_unlock_bh(&session->reorder_q.lock); 480 } 481 482 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr) 483 { 484 u32 nws; 485 486 if (nr >= session->nr) 487 nws = nr - session->nr; 488 else 489 nws = (session->nr_max + 1) - (session->nr - nr); 490 491 return nws < session->nr_window_size; 492 } 493 494 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if 495 * acceptable, else non-zero. 496 */ 497 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb) 498 { 499 if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) { 500 /* Packet sequence number is outside allowed window. 501 * Discard it. 502 */ 503 l2tp_dbg(session, L2TP_MSG_SEQ, 504 "%s: pkt %u len %d discarded, outside window, nr=%u\n", 505 session->name, L2TP_SKB_CB(skb)->ns, 506 L2TP_SKB_CB(skb)->length, session->nr); 507 goto discard; 508 } 509 510 if (session->reorder_timeout != 0) { 511 /* Packet reordering enabled. Add skb to session's 512 * reorder queue, in order of ns. 513 */ 514 l2tp_recv_queue_skb(session, skb); 515 goto out; 516 } 517 518 /* Packet reordering disabled. Discard out-of-sequence packets, while 519 * tracking the number if in-sequence packets after the first OOS packet 520 * is seen. After nr_oos_count_max in-sequence packets, reset the 521 * sequence number to re-enable packet reception. 522 */ 523 if (L2TP_SKB_CB(skb)->ns == session->nr) { 524 skb_queue_tail(&session->reorder_q, skb); 525 } else { 526 u32 nr_oos = L2TP_SKB_CB(skb)->ns; 527 u32 nr_next = (session->nr_oos + 1) & session->nr_max; 528 529 if (nr_oos == nr_next) 530 session->nr_oos_count++; 531 else 532 session->nr_oos_count = 0; 533 534 session->nr_oos = nr_oos; 535 if (session->nr_oos_count > session->nr_oos_count_max) { 536 session->reorder_skip = 1; 537 l2tp_dbg(session, L2TP_MSG_SEQ, 538 "%s: %d oos packets received. Resetting sequence numbers\n", 539 session->name, session->nr_oos_count); 540 } 541 if (!session->reorder_skip) { 542 atomic_long_inc(&session->stats.rx_seq_discards); 543 l2tp_dbg(session, L2TP_MSG_SEQ, 544 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n", 545 session->name, L2TP_SKB_CB(skb)->ns, 546 L2TP_SKB_CB(skb)->length, session->nr, 547 skb_queue_len(&session->reorder_q)); 548 goto discard; 549 } 550 skb_queue_tail(&session->reorder_q, skb); 551 } 552 553 out: 554 return 0; 555 556 discard: 557 return 1; 558 } 559 560 /* Do receive processing of L2TP data frames. We handle both L2TPv2 561 * and L2TPv3 data frames here. 562 * 563 * L2TPv2 Data Message Header 564 * 565 * 0 1 2 3 566 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 567 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 568 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) | 569 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 570 * | Tunnel ID | Session ID | 571 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 572 * | Ns (opt) | Nr (opt) | 573 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 574 * | Offset Size (opt) | Offset pad... (opt) 575 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 576 * 577 * Data frames are marked by T=0. All other fields are the same as 578 * those in L2TP control frames. 579 * 580 * L2TPv3 Data Message Header 581 * 582 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 583 * | L2TP Session Header | 584 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 585 * | L2-Specific Sublayer | 586 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 587 * | Tunnel Payload ... 588 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 589 * 590 * L2TPv3 Session Header Over IP 591 * 592 * 0 1 2 3 593 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 594 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 595 * | Session ID | 596 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 597 * | Cookie (optional, maximum 64 bits)... 598 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 599 * | 600 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 601 * 602 * L2TPv3 L2-Specific Sublayer Format 603 * 604 * 0 1 2 3 605 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 606 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 607 * |x|S|x|x|x|x|x|x| Sequence Number | 608 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 609 * 610 * Cookie value and sublayer format are negotiated with the peer when 611 * the session is set up. Unlike L2TPv2, we do not need to parse the 612 * packet header to determine if optional fields are present. 613 * 614 * Caller must already have parsed the frame and determined that it is 615 * a data (not control) frame before coming here. Fields up to the 616 * session-id have already been parsed and ptr points to the data 617 * after the session-id. 618 */ 619 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 620 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 621 int length) 622 { 623 struct l2tp_tunnel *tunnel = session->tunnel; 624 int offset; 625 u32 ns, nr; 626 627 /* Parse and check optional cookie */ 628 if (session->peer_cookie_len > 0) { 629 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { 630 l2tp_info(tunnel, L2TP_MSG_DATA, 631 "%s: cookie mismatch (%u/%u). Discarding.\n", 632 tunnel->name, tunnel->tunnel_id, 633 session->session_id); 634 atomic_long_inc(&session->stats.rx_cookie_discards); 635 goto discard; 636 } 637 ptr += session->peer_cookie_len; 638 } 639 640 /* Handle the optional sequence numbers. Sequence numbers are 641 * in different places for L2TPv2 and L2TPv3. 642 * 643 * If we are the LAC, enable/disable sequence numbers under 644 * the control of the LNS. If no sequence numbers present but 645 * we were expecting them, discard frame. 646 */ 647 ns = nr = 0; 648 L2TP_SKB_CB(skb)->has_seq = 0; 649 if (tunnel->version == L2TP_HDR_VER_2) { 650 if (hdrflags & L2TP_HDRFLAG_S) { 651 ns = ntohs(*(__be16 *) ptr); 652 ptr += 2; 653 nr = ntohs(*(__be16 *) ptr); 654 ptr += 2; 655 656 /* Store L2TP info in the skb */ 657 L2TP_SKB_CB(skb)->ns = ns; 658 L2TP_SKB_CB(skb)->has_seq = 1; 659 660 l2tp_dbg(session, L2TP_MSG_SEQ, 661 "%s: recv data ns=%u, nr=%u, session nr=%u\n", 662 session->name, ns, nr, session->nr); 663 } 664 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 665 u32 l2h = ntohl(*(__be32 *) ptr); 666 667 if (l2h & 0x40000000) { 668 ns = l2h & 0x00ffffff; 669 670 /* Store L2TP info in the skb */ 671 L2TP_SKB_CB(skb)->ns = ns; 672 L2TP_SKB_CB(skb)->has_seq = 1; 673 674 l2tp_dbg(session, L2TP_MSG_SEQ, 675 "%s: recv data ns=%u, session nr=%u\n", 676 session->name, ns, session->nr); 677 } 678 ptr += 4; 679 } 680 681 if (L2TP_SKB_CB(skb)->has_seq) { 682 /* Received a packet with sequence numbers. If we're the LNS, 683 * check if we sre sending sequence numbers and if not, 684 * configure it so. 685 */ 686 if ((!session->lns_mode) && (!session->send_seq)) { 687 l2tp_info(session, L2TP_MSG_SEQ, 688 "%s: requested to enable seq numbers by LNS\n", 689 session->name); 690 session->send_seq = 1; 691 l2tp_session_set_header_len(session, tunnel->version); 692 } 693 } else { 694 /* No sequence numbers. 695 * If user has configured mandatory sequence numbers, discard. 696 */ 697 if (session->recv_seq) { 698 l2tp_warn(session, L2TP_MSG_SEQ, 699 "%s: recv data has no seq numbers when required. Discarding.\n", 700 session->name); 701 atomic_long_inc(&session->stats.rx_seq_discards); 702 goto discard; 703 } 704 705 /* If we're the LAC and we're sending sequence numbers, the 706 * LNS has requested that we no longer send sequence numbers. 707 * If we're the LNS and we're sending sequence numbers, the 708 * LAC is broken. Discard the frame. 709 */ 710 if ((!session->lns_mode) && (session->send_seq)) { 711 l2tp_info(session, L2TP_MSG_SEQ, 712 "%s: requested to disable seq numbers by LNS\n", 713 session->name); 714 session->send_seq = 0; 715 l2tp_session_set_header_len(session, tunnel->version); 716 } else if (session->send_seq) { 717 l2tp_warn(session, L2TP_MSG_SEQ, 718 "%s: recv data has no seq numbers when required. Discarding.\n", 719 session->name); 720 atomic_long_inc(&session->stats.rx_seq_discards); 721 goto discard; 722 } 723 } 724 725 /* Session data offset is defined only for L2TPv2 and is 726 * indicated by an optional 16-bit value in the header. 727 */ 728 if (tunnel->version == L2TP_HDR_VER_2) { 729 /* If offset bit set, skip it. */ 730 if (hdrflags & L2TP_HDRFLAG_O) { 731 offset = ntohs(*(__be16 *)ptr); 732 ptr += 2 + offset; 733 } 734 } 735 736 offset = ptr - optr; 737 if (!pskb_may_pull(skb, offset)) 738 goto discard; 739 740 __skb_pull(skb, offset); 741 742 /* Prepare skb for adding to the session's reorder_q. Hold 743 * packets for max reorder_timeout or 1 second if not 744 * reordering. 745 */ 746 L2TP_SKB_CB(skb)->length = length; 747 L2TP_SKB_CB(skb)->expires = jiffies + 748 (session->reorder_timeout ? session->reorder_timeout : HZ); 749 750 /* Add packet to the session's receive queue. Reordering is done here, if 751 * enabled. Saved L2TP protocol info is stored in skb->sb[]. 752 */ 753 if (L2TP_SKB_CB(skb)->has_seq) { 754 if (l2tp_recv_data_seq(session, skb)) 755 goto discard; 756 } else { 757 /* No sequence numbers. Add the skb to the tail of the 758 * reorder queue. This ensures that it will be 759 * delivered after all previous sequenced skbs. 760 */ 761 skb_queue_tail(&session->reorder_q, skb); 762 } 763 764 /* Try to dequeue as many skbs from reorder_q as we can. */ 765 l2tp_recv_dequeue(session); 766 767 return; 768 769 discard: 770 atomic_long_inc(&session->stats.rx_errors); 771 kfree_skb(skb); 772 } 773 EXPORT_SYMBOL(l2tp_recv_common); 774 775 /* Drop skbs from the session's reorder_q 776 */ 777 static int l2tp_session_queue_purge(struct l2tp_session *session) 778 { 779 struct sk_buff *skb = NULL; 780 BUG_ON(!session); 781 BUG_ON(session->magic != L2TP_SESSION_MAGIC); 782 while ((skb = skb_dequeue(&session->reorder_q))) { 783 atomic_long_inc(&session->stats.rx_errors); 784 kfree_skb(skb); 785 } 786 return 0; 787 } 788 789 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame 790 * here. The skb is not on a list when we get here. 791 * Returns 0 if the packet was a data packet and was successfully passed on. 792 * Returns 1 if the packet was not a good data packet and could not be 793 * forwarded. All such packets are passed up to userspace to deal with. 794 */ 795 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb) 796 { 797 struct l2tp_session *session = NULL; 798 unsigned char *ptr, *optr; 799 u16 hdrflags; 800 u32 tunnel_id, session_id; 801 u16 version; 802 int length; 803 804 /* UDP has verifed checksum */ 805 806 /* UDP always verifies the packet length. */ 807 __skb_pull(skb, sizeof(struct udphdr)); 808 809 /* Short packet? */ 810 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX)) { 811 l2tp_info(tunnel, L2TP_MSG_DATA, 812 "%s: recv short packet (len=%d)\n", 813 tunnel->name, skb->len); 814 goto error; 815 } 816 817 /* Trace packet contents, if enabled */ 818 if (tunnel->debug & L2TP_MSG_DATA) { 819 length = min(32u, skb->len); 820 if (!pskb_may_pull(skb, length)) 821 goto error; 822 823 pr_debug("%s: recv\n", tunnel->name); 824 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 825 } 826 827 /* Point to L2TP header */ 828 optr = ptr = skb->data; 829 830 /* Get L2TP header flags */ 831 hdrflags = ntohs(*(__be16 *) ptr); 832 833 /* Check protocol version */ 834 version = hdrflags & L2TP_HDR_VER_MASK; 835 if (version != tunnel->version) { 836 l2tp_info(tunnel, L2TP_MSG_DATA, 837 "%s: recv protocol version mismatch: got %d expected %d\n", 838 tunnel->name, version, tunnel->version); 839 goto error; 840 } 841 842 /* Get length of L2TP packet */ 843 length = skb->len; 844 845 /* If type is control packet, it is handled by userspace. */ 846 if (hdrflags & L2TP_HDRFLAG_T) { 847 l2tp_dbg(tunnel, L2TP_MSG_DATA, 848 "%s: recv control packet, len=%d\n", 849 tunnel->name, length); 850 goto error; 851 } 852 853 /* Skip flags */ 854 ptr += 2; 855 856 if (tunnel->version == L2TP_HDR_VER_2) { 857 /* If length is present, skip it */ 858 if (hdrflags & L2TP_HDRFLAG_L) 859 ptr += 2; 860 861 /* Extract tunnel and session ID */ 862 tunnel_id = ntohs(*(__be16 *) ptr); 863 ptr += 2; 864 session_id = ntohs(*(__be16 *) ptr); 865 ptr += 2; 866 } else { 867 ptr += 2; /* skip reserved bits */ 868 tunnel_id = tunnel->tunnel_id; 869 session_id = ntohl(*(__be32 *) ptr); 870 ptr += 4; 871 } 872 873 /* Find the session context */ 874 session = l2tp_tunnel_get_session(tunnel, session_id); 875 if (!session || !session->recv_skb) { 876 if (session) 877 l2tp_session_dec_refcount(session); 878 879 /* Not found? Pass to userspace to deal with */ 880 l2tp_info(tunnel, L2TP_MSG_DATA, 881 "%s: no session found (%u/%u). Passing up.\n", 882 tunnel->name, tunnel_id, session_id); 883 goto error; 884 } 885 886 if (tunnel->version == L2TP_HDR_VER_3 && 887 l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) 888 goto error; 889 890 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length); 891 l2tp_session_dec_refcount(session); 892 893 return 0; 894 895 error: 896 /* Put UDP header back */ 897 __skb_push(skb, sizeof(struct udphdr)); 898 899 return 1; 900 } 901 902 /* UDP encapsulation receive handler. See net/ipv4/udp.c. 903 * Return codes: 904 * 0 : success. 905 * <0: error 906 * >0: skb should be passed up to userspace as UDP. 907 */ 908 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 909 { 910 struct l2tp_tunnel *tunnel; 911 912 tunnel = rcu_dereference_sk_user_data(sk); 913 if (tunnel == NULL) 914 goto pass_up; 915 916 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n", 917 tunnel->name, skb->len); 918 919 if (l2tp_udp_recv_core(tunnel, skb)) 920 goto pass_up; 921 922 return 0; 923 924 pass_up: 925 return 1; 926 } 927 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 928 929 /************************************************************************ 930 * Transmit handling 931 ***********************************************************************/ 932 933 /* Build an L2TP header for the session into the buffer provided. 934 */ 935 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 936 { 937 struct l2tp_tunnel *tunnel = session->tunnel; 938 __be16 *bufp = buf; 939 __be16 *optr = buf; 940 u16 flags = L2TP_HDR_VER_2; 941 u32 tunnel_id = tunnel->peer_tunnel_id; 942 u32 session_id = session->peer_session_id; 943 944 if (session->send_seq) 945 flags |= L2TP_HDRFLAG_S; 946 947 /* Setup L2TP header. */ 948 *bufp++ = htons(flags); 949 *bufp++ = htons(tunnel_id); 950 *bufp++ = htons(session_id); 951 if (session->send_seq) { 952 *bufp++ = htons(session->ns); 953 *bufp++ = 0; 954 session->ns++; 955 session->ns &= 0xffff; 956 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n", 957 session->name, session->ns); 958 } 959 960 return bufp - optr; 961 } 962 963 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 964 { 965 struct l2tp_tunnel *tunnel = session->tunnel; 966 char *bufp = buf; 967 char *optr = bufp; 968 969 /* Setup L2TP header. The header differs slightly for UDP and 970 * IP encapsulations. For UDP, there is 4 bytes of flags. 971 */ 972 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 973 u16 flags = L2TP_HDR_VER_3; 974 *((__be16 *) bufp) = htons(flags); 975 bufp += 2; 976 *((__be16 *) bufp) = 0; 977 bufp += 2; 978 } 979 980 *((__be32 *) bufp) = htonl(session->peer_session_id); 981 bufp += 4; 982 if (session->cookie_len) { 983 memcpy(bufp, &session->cookie[0], session->cookie_len); 984 bufp += session->cookie_len; 985 } 986 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 987 u32 l2h = 0; 988 989 if (session->send_seq) { 990 l2h = 0x40000000 | session->ns; 991 session->ns++; 992 session->ns &= 0xffffff; 993 l2tp_dbg(session, L2TP_MSG_SEQ, 994 "%s: updated ns to %u\n", 995 session->name, session->ns); 996 } 997 998 *((__be32 *)bufp) = htonl(l2h); 999 bufp += 4; 1000 } 1001 1002 return bufp - optr; 1003 } 1004 1005 static void l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, 1006 struct flowi *fl, size_t data_len) 1007 { 1008 struct l2tp_tunnel *tunnel = session->tunnel; 1009 unsigned int len = skb->len; 1010 int error; 1011 1012 /* Debug */ 1013 if (session->send_seq) 1014 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes, ns=%u\n", 1015 session->name, data_len, session->ns - 1); 1016 else 1017 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes\n", 1018 session->name, data_len); 1019 1020 if (session->debug & L2TP_MSG_DATA) { 1021 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1022 unsigned char *datap = skb->data + uhlen; 1023 1024 pr_debug("%s: xmit\n", session->name); 1025 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, 1026 datap, min_t(size_t, 32, len - uhlen)); 1027 } 1028 1029 /* Queue the packet to IP for output */ 1030 skb->ignore_df = 1; 1031 skb_dst_drop(skb); 1032 #if IS_ENABLED(CONFIG_IPV6) 1033 if (l2tp_sk_is_v6(tunnel->sock)) 1034 error = inet6_csk_xmit(tunnel->sock, skb, NULL); 1035 else 1036 #endif 1037 error = ip_queue_xmit(tunnel->sock, skb, fl); 1038 1039 /* Update stats */ 1040 if (error >= 0) { 1041 atomic_long_inc(&tunnel->stats.tx_packets); 1042 atomic_long_add(len, &tunnel->stats.tx_bytes); 1043 atomic_long_inc(&session->stats.tx_packets); 1044 atomic_long_add(len, &session->stats.tx_bytes); 1045 } else { 1046 atomic_long_inc(&tunnel->stats.tx_errors); 1047 atomic_long_inc(&session->stats.tx_errors); 1048 } 1049 } 1050 1051 /* If caller requires the skb to have a ppp header, the header must be 1052 * inserted in the skb data before calling this function. 1053 */ 1054 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len) 1055 { 1056 int data_len = skb->len; 1057 struct l2tp_tunnel *tunnel = session->tunnel; 1058 struct sock *sk = tunnel->sock; 1059 struct flowi *fl; 1060 struct udphdr *uh; 1061 struct inet_sock *inet; 1062 int headroom; 1063 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1064 int udp_len; 1065 int ret = NET_XMIT_SUCCESS; 1066 1067 /* Check that there's enough headroom in the skb to insert IP, 1068 * UDP and L2TP headers. If not enough, expand it to 1069 * make room. Adjust truesize. 1070 */ 1071 headroom = NET_SKB_PAD + sizeof(struct iphdr) + 1072 uhlen + hdr_len; 1073 if (skb_cow_head(skb, headroom)) { 1074 kfree_skb(skb); 1075 return NET_XMIT_DROP; 1076 } 1077 1078 /* Setup L2TP header */ 1079 session->build_header(session, __skb_push(skb, hdr_len)); 1080 1081 /* Reset skb netfilter state */ 1082 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1083 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | 1084 IPSKB_REROUTED); 1085 nf_reset_ct(skb); 1086 1087 bh_lock_sock(sk); 1088 if (sock_owned_by_user(sk)) { 1089 kfree_skb(skb); 1090 ret = NET_XMIT_DROP; 1091 goto out_unlock; 1092 } 1093 1094 /* The user-space may change the connection status for the user-space 1095 * provided socket at run time: we must check it under the socket lock 1096 */ 1097 if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) { 1098 kfree_skb(skb); 1099 ret = NET_XMIT_DROP; 1100 goto out_unlock; 1101 } 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 (sk->sk_family != PF_INET && sk->sk_family != PF_INET6) 1459 return -EPROTONOSUPPORT; 1460 1461 if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) || 1462 (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP)) 1463 return -EPROTONOSUPPORT; 1464 1465 if (sk->sk_user_data) 1466 return -EBUSY; 1467 1468 return 0; 1469 } 1470 1471 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 1472 struct l2tp_tunnel_cfg *cfg) 1473 { 1474 struct l2tp_tunnel *tunnel_walk; 1475 struct l2tp_net *pn; 1476 struct socket *sock; 1477 struct sock *sk; 1478 int ret; 1479 1480 if (tunnel->fd < 0) { 1481 ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id, 1482 tunnel->peer_tunnel_id, cfg, 1483 &sock); 1484 if (ret < 0) 1485 goto err; 1486 } else { 1487 sock = sockfd_lookup(tunnel->fd, &ret); 1488 if (!sock) 1489 goto err; 1490 1491 ret = l2tp_validate_socket(sock->sk, net, tunnel->encap); 1492 if (ret < 0) 1493 goto err_sock; 1494 } 1495 1496 tunnel->l2tp_net = net; 1497 pn = l2tp_pernet(net); 1498 1499 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1500 list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) { 1501 if (tunnel_walk->tunnel_id == tunnel->tunnel_id) { 1502 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1503 1504 ret = -EEXIST; 1505 goto err_sock; 1506 } 1507 } 1508 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); 1509 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1510 1511 sk = sock->sk; 1512 sock_hold(sk); 1513 tunnel->sock = sk; 1514 1515 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1516 struct udp_tunnel_sock_cfg udp_cfg = { 1517 .sk_user_data = tunnel, 1518 .encap_type = UDP_ENCAP_L2TPINUDP, 1519 .encap_rcv = l2tp_udp_encap_recv, 1520 .encap_destroy = l2tp_udp_encap_destroy, 1521 }; 1522 1523 setup_udp_tunnel_sock(net, sock, &udp_cfg); 1524 } else { 1525 sk->sk_user_data = tunnel; 1526 } 1527 1528 tunnel->old_sk_destruct = sk->sk_destruct; 1529 sk->sk_destruct = &l2tp_tunnel_destruct; 1530 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, 1531 "l2tp_sock"); 1532 sk->sk_allocation = GFP_ATOMIC; 1533 1534 if (tunnel->fd >= 0) 1535 sockfd_put(sock); 1536 1537 return 0; 1538 1539 err_sock: 1540 if (tunnel->fd < 0) 1541 sock_release(sock); 1542 else 1543 sockfd_put(sock); 1544 err: 1545 return ret; 1546 } 1547 EXPORT_SYMBOL_GPL(l2tp_tunnel_register); 1548 1549 /* This function is used by the netlink TUNNEL_DELETE command. 1550 */ 1551 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1552 { 1553 if (!test_and_set_bit(0, &tunnel->dead)) { 1554 l2tp_tunnel_inc_refcount(tunnel); 1555 queue_work(l2tp_wq, &tunnel->del_work); 1556 } 1557 } 1558 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1559 1560 /* Really kill the session. 1561 */ 1562 void l2tp_session_free(struct l2tp_session *session) 1563 { 1564 struct l2tp_tunnel *tunnel = session->tunnel; 1565 1566 BUG_ON(refcount_read(&session->ref_count) != 0); 1567 1568 if (tunnel) { 1569 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC); 1570 l2tp_tunnel_dec_refcount(tunnel); 1571 } 1572 1573 kfree(session); 1574 } 1575 EXPORT_SYMBOL_GPL(l2tp_session_free); 1576 1577 /* Remove an l2tp session from l2tp_core's hash lists. 1578 * Provides a tidyup interface for pseudowire code which can't just route all 1579 * shutdown via. l2tp_session_delete and a pseudowire-specific session_close 1580 * callback. 1581 */ 1582 void __l2tp_session_unhash(struct l2tp_session *session) 1583 { 1584 struct l2tp_tunnel *tunnel = session->tunnel; 1585 1586 /* Remove the session from core hashes */ 1587 if (tunnel) { 1588 /* Remove from the per-tunnel hash */ 1589 write_lock_bh(&tunnel->hlist_lock); 1590 hlist_del_init(&session->hlist); 1591 write_unlock_bh(&tunnel->hlist_lock); 1592 1593 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1594 if (tunnel->version != L2TP_HDR_VER_2) { 1595 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1596 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1597 hlist_del_init_rcu(&session->global_hlist); 1598 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1599 synchronize_rcu(); 1600 } 1601 } 1602 } 1603 EXPORT_SYMBOL_GPL(__l2tp_session_unhash); 1604 1605 /* This function is used by the netlink SESSION_DELETE command and by 1606 pseudowire modules. 1607 */ 1608 int l2tp_session_delete(struct l2tp_session *session) 1609 { 1610 if (test_and_set_bit(0, &session->dead)) 1611 return 0; 1612 1613 __l2tp_session_unhash(session); 1614 l2tp_session_queue_purge(session); 1615 if (session->session_close != NULL) 1616 (*session->session_close)(session); 1617 1618 l2tp_session_dec_refcount(session); 1619 1620 return 0; 1621 } 1622 EXPORT_SYMBOL_GPL(l2tp_session_delete); 1623 1624 /* We come here whenever a session's send_seq, cookie_len or 1625 * l2specific_type parameters are set. 1626 */ 1627 void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1628 { 1629 if (version == L2TP_HDR_VER_2) { 1630 session->hdr_len = 6; 1631 if (session->send_seq) 1632 session->hdr_len += 4; 1633 } else { 1634 session->hdr_len = 4 + session->cookie_len; 1635 session->hdr_len += l2tp_get_l2specific_len(session); 1636 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1637 session->hdr_len += 4; 1638 } 1639 1640 } 1641 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1642 1643 struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg) 1644 { 1645 struct l2tp_session *session; 1646 1647 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL); 1648 if (session != NULL) { 1649 session->magic = L2TP_SESSION_MAGIC; 1650 session->tunnel = tunnel; 1651 1652 session->session_id = session_id; 1653 session->peer_session_id = peer_session_id; 1654 session->nr = 0; 1655 if (tunnel->version == L2TP_HDR_VER_2) 1656 session->nr_max = 0xffff; 1657 else 1658 session->nr_max = 0xffffff; 1659 session->nr_window_size = session->nr_max / 2; 1660 session->nr_oos_count_max = 4; 1661 1662 /* Use NR of first received packet */ 1663 session->reorder_skip = 1; 1664 1665 sprintf(&session->name[0], "sess %u/%u", 1666 tunnel->tunnel_id, session->session_id); 1667 1668 skb_queue_head_init(&session->reorder_q); 1669 1670 INIT_HLIST_NODE(&session->hlist); 1671 INIT_HLIST_NODE(&session->global_hlist); 1672 1673 /* Inherit debug options from tunnel */ 1674 session->debug = tunnel->debug; 1675 1676 if (cfg) { 1677 session->pwtype = cfg->pw_type; 1678 session->debug = cfg->debug; 1679 session->send_seq = cfg->send_seq; 1680 session->recv_seq = cfg->recv_seq; 1681 session->lns_mode = cfg->lns_mode; 1682 session->reorder_timeout = cfg->reorder_timeout; 1683 session->l2specific_type = cfg->l2specific_type; 1684 session->cookie_len = cfg->cookie_len; 1685 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1686 session->peer_cookie_len = cfg->peer_cookie_len; 1687 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1688 } 1689 1690 if (tunnel->version == L2TP_HDR_VER_2) 1691 session->build_header = l2tp_build_l2tpv2_header; 1692 else 1693 session->build_header = l2tp_build_l2tpv3_header; 1694 1695 l2tp_session_set_header_len(session, tunnel->version); 1696 1697 refcount_set(&session->ref_count, 1); 1698 1699 return session; 1700 } 1701 1702 return ERR_PTR(-ENOMEM); 1703 } 1704 EXPORT_SYMBOL_GPL(l2tp_session_create); 1705 1706 /***************************************************************************** 1707 * Init and cleanup 1708 *****************************************************************************/ 1709 1710 static __net_init int l2tp_init_net(struct net *net) 1711 { 1712 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1713 int hash; 1714 1715 INIT_LIST_HEAD(&pn->l2tp_tunnel_list); 1716 spin_lock_init(&pn->l2tp_tunnel_list_lock); 1717 1718 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1719 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1720 1721 spin_lock_init(&pn->l2tp_session_hlist_lock); 1722 1723 return 0; 1724 } 1725 1726 static __net_exit void l2tp_exit_net(struct net *net) 1727 { 1728 struct l2tp_net *pn = l2tp_pernet(net); 1729 struct l2tp_tunnel *tunnel = NULL; 1730 int hash; 1731 1732 rcu_read_lock_bh(); 1733 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 1734 l2tp_tunnel_delete(tunnel); 1735 } 1736 rcu_read_unlock_bh(); 1737 1738 if (l2tp_wq) 1739 flush_workqueue(l2tp_wq); 1740 rcu_barrier(); 1741 1742 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1743 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); 1744 } 1745 1746 static struct pernet_operations l2tp_net_ops = { 1747 .init = l2tp_init_net, 1748 .exit = l2tp_exit_net, 1749 .id = &l2tp_net_id, 1750 .size = sizeof(struct l2tp_net), 1751 }; 1752 1753 static int __init l2tp_init(void) 1754 { 1755 int rc = 0; 1756 1757 rc = register_pernet_device(&l2tp_net_ops); 1758 if (rc) 1759 goto out; 1760 1761 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1762 if (!l2tp_wq) { 1763 pr_err("alloc_workqueue failed\n"); 1764 unregister_pernet_device(&l2tp_net_ops); 1765 rc = -ENOMEM; 1766 goto out; 1767 } 1768 1769 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 1770 1771 out: 1772 return rc; 1773 } 1774 1775 static void __exit l2tp_exit(void) 1776 { 1777 unregister_pernet_device(&l2tp_net_ops); 1778 if (l2tp_wq) { 1779 destroy_workqueue(l2tp_wq); 1780 l2tp_wq = NULL; 1781 } 1782 } 1783 1784 module_init(l2tp_init); 1785 module_exit(l2tp_exit); 1786 1787 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1788 MODULE_DESCRIPTION("L2TP core"); 1789 MODULE_LICENSE("GPL"); 1790 MODULE_VERSION(L2TP_DRV_VERSION); 1791