1 // SPDX-License-Identifier: GPL-2.0-only 2 /* L2TP core. 3 * 4 * Copyright (c) 2008,2009,2010 Katalix Systems Ltd 5 * 6 * This file contains some code of the original L2TPv2 pppol2tp 7 * driver, which has the following copyright: 8 * 9 * Authors: Martijn van Oosterhout <kleptog@svana.org> 10 * James Chapman (jchapman@katalix.com) 11 * Contributors: 12 * Michal Ostrowski <mostrows@speakeasy.net> 13 * Arnaldo Carvalho de Melo <acme@xconectiva.com.br> 14 * David S. Miller (davem@redhat.com) 15 */ 16 17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 18 19 #include <linux/module.h> 20 #include <linux/string.h> 21 #include <linux/list.h> 22 #include <linux/rculist.h> 23 #include <linux/uaccess.h> 24 25 #include <linux/kernel.h> 26 #include <linux/spinlock.h> 27 #include <linux/kthread.h> 28 #include <linux/sched.h> 29 #include <linux/slab.h> 30 #include <linux/errno.h> 31 #include <linux/jiffies.h> 32 33 #include <linux/netdevice.h> 34 #include <linux/net.h> 35 #include <linux/inetdevice.h> 36 #include <linux/skbuff.h> 37 #include <linux/init.h> 38 #include <linux/in.h> 39 #include <linux/ip.h> 40 #include <linux/udp.h> 41 #include <linux/l2tp.h> 42 #include <linux/hash.h> 43 #include <linux/sort.h> 44 #include <linux/file.h> 45 #include <linux/nsproxy.h> 46 #include <net/net_namespace.h> 47 #include <net/netns/generic.h> 48 #include <net/dst.h> 49 #include <net/ip.h> 50 #include <net/udp.h> 51 #include <net/udp_tunnel.h> 52 #include <net/inet_common.h> 53 #include <net/xfrm.h> 54 #include <net/protocol.h> 55 #include <net/inet6_connection_sock.h> 56 #include <net/inet_ecn.h> 57 #include <net/ip6_route.h> 58 #include <net/ip6_checksum.h> 59 60 #include <asm/byteorder.h> 61 #include <linux/atomic.h> 62 63 #include "l2tp_core.h" 64 #include "trace.h" 65 66 #define CREATE_TRACE_POINTS 67 #include "trace.h" 68 69 #define L2TP_DRV_VERSION "V2.0" 70 71 /* L2TP header constants */ 72 #define L2TP_HDRFLAG_T 0x8000 73 #define L2TP_HDRFLAG_L 0x4000 74 #define L2TP_HDRFLAG_S 0x0800 75 #define L2TP_HDRFLAG_O 0x0200 76 #define L2TP_HDRFLAG_P 0x0100 77 78 #define L2TP_HDR_VER_MASK 0x000F 79 #define L2TP_HDR_VER_2 0x0002 80 #define L2TP_HDR_VER_3 0x0003 81 82 /* L2TPv3 default L2-specific sublayer */ 83 #define L2TP_SLFLAG_S 0x40000000 84 #define L2TP_SL_SEQ_MASK 0x00ffffff 85 86 #define L2TP_HDR_SIZE_MAX 14 87 88 /* Default trace flags */ 89 #define L2TP_DEFAULT_DEBUG_FLAGS 0 90 91 /* Private data stored for received packets in the skb. 92 */ 93 struct l2tp_skb_cb { 94 u32 ns; 95 u16 has_seq; 96 u16 length; 97 unsigned long expires; 98 }; 99 100 #define L2TP_SKB_CB(skb) ((struct l2tp_skb_cb *)&(skb)->cb[sizeof(struct inet_skb_parm)]) 101 102 static struct workqueue_struct *l2tp_wq; 103 104 /* per-net private data for this module */ 105 static unsigned int l2tp_net_id; 106 struct l2tp_net { 107 /* Lock for write access to l2tp_tunnel_idr */ 108 spinlock_t l2tp_tunnel_idr_lock; 109 struct idr l2tp_tunnel_idr; 110 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; 111 /* Lock for write access to l2tp_session_hlist */ 112 spinlock_t l2tp_session_hlist_lock; 113 }; 114 115 #if IS_ENABLED(CONFIG_IPV6) 116 static bool l2tp_sk_is_v6(struct sock *sk) 117 { 118 return sk->sk_family == PF_INET6 && 119 !ipv6_addr_v4mapped(&sk->sk_v6_daddr); 120 } 121 #endif 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 /* Session hash list. 140 * The session_id SHOULD be random according to RFC2661, but several 141 * L2TP implementations (Cisco and Microsoft) use incrementing 142 * session_ids. So we do a real hash on the session_id, rather than a 143 * simple bitmask. 144 */ 145 static inline struct hlist_head * 146 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id) 147 { 148 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)]; 149 } 150 151 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) 152 { 153 trace_free_tunnel(tunnel); 154 sock_put(tunnel->sock); 155 /* the tunnel is freed in the socket destructor */ 156 } 157 158 static void l2tp_session_free(struct l2tp_session *session) 159 { 160 trace_free_session(session); 161 if (session->tunnel) 162 l2tp_tunnel_dec_refcount(session->tunnel); 163 kfree(session); 164 } 165 166 struct l2tp_tunnel *l2tp_sk_to_tunnel(struct sock *sk) 167 { 168 struct l2tp_tunnel *tunnel = sk->sk_user_data; 169 170 if (tunnel) 171 if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC)) 172 return NULL; 173 174 return tunnel; 175 } 176 EXPORT_SYMBOL_GPL(l2tp_sk_to_tunnel); 177 178 void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel) 179 { 180 refcount_inc(&tunnel->ref_count); 181 } 182 EXPORT_SYMBOL_GPL(l2tp_tunnel_inc_refcount); 183 184 void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel) 185 { 186 if (refcount_dec_and_test(&tunnel->ref_count)) 187 l2tp_tunnel_free(tunnel); 188 } 189 EXPORT_SYMBOL_GPL(l2tp_tunnel_dec_refcount); 190 191 void l2tp_session_inc_refcount(struct l2tp_session *session) 192 { 193 refcount_inc(&session->ref_count); 194 } 195 EXPORT_SYMBOL_GPL(l2tp_session_inc_refcount); 196 197 void l2tp_session_dec_refcount(struct l2tp_session *session) 198 { 199 if (refcount_dec_and_test(&session->ref_count)) 200 l2tp_session_free(session); 201 } 202 EXPORT_SYMBOL_GPL(l2tp_session_dec_refcount); 203 204 /* Lookup a tunnel. A new reference is held on the returned tunnel. */ 205 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) 206 { 207 const struct l2tp_net *pn = l2tp_pernet(net); 208 struct l2tp_tunnel *tunnel; 209 210 rcu_read_lock_bh(); 211 tunnel = idr_find(&pn->l2tp_tunnel_idr, tunnel_id); 212 if (tunnel && refcount_inc_not_zero(&tunnel->ref_count)) { 213 rcu_read_unlock_bh(); 214 return tunnel; 215 } 216 rcu_read_unlock_bh(); 217 218 return NULL; 219 } 220 EXPORT_SYMBOL_GPL(l2tp_tunnel_get); 221 222 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) 223 { 224 struct l2tp_net *pn = l2tp_pernet(net); 225 unsigned long tunnel_id, tmp; 226 struct l2tp_tunnel *tunnel; 227 int count = 0; 228 229 rcu_read_lock_bh(); 230 idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) { 231 if (tunnel && ++count > nth && 232 refcount_inc_not_zero(&tunnel->ref_count)) { 233 rcu_read_unlock_bh(); 234 return tunnel; 235 } 236 } 237 rcu_read_unlock_bh(); 238 239 return NULL; 240 } 241 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth); 242 243 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel, 244 u32 session_id) 245 { 246 struct hlist_head *session_list; 247 struct l2tp_session *session; 248 249 session_list = l2tp_session_id_hash(tunnel, session_id); 250 251 rcu_read_lock_bh(); 252 hlist_for_each_entry_rcu(session, session_list, hlist) 253 if (session->session_id == session_id) { 254 l2tp_session_inc_refcount(session); 255 rcu_read_unlock_bh(); 256 257 return session; 258 } 259 rcu_read_unlock_bh(); 260 261 return NULL; 262 } 263 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_session); 264 265 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id) 266 { 267 struct hlist_head *session_list; 268 struct l2tp_session *session; 269 270 session_list = l2tp_session_id_hash_2(l2tp_pernet(net), session_id); 271 272 rcu_read_lock_bh(); 273 hlist_for_each_entry_rcu(session, session_list, global_hlist) 274 if (session->session_id == session_id) { 275 l2tp_session_inc_refcount(session); 276 rcu_read_unlock_bh(); 277 278 return session; 279 } 280 rcu_read_unlock_bh(); 281 282 return NULL; 283 } 284 EXPORT_SYMBOL_GPL(l2tp_session_get); 285 286 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth) 287 { 288 int hash; 289 struct l2tp_session *session; 290 int count = 0; 291 292 rcu_read_lock_bh(); 293 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 294 hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) { 295 if (++count > nth) { 296 l2tp_session_inc_refcount(session); 297 rcu_read_unlock_bh(); 298 return session; 299 } 300 } 301 } 302 303 rcu_read_unlock_bh(); 304 305 return NULL; 306 } 307 EXPORT_SYMBOL_GPL(l2tp_session_get_nth); 308 309 /* Lookup a session by interface name. 310 * This is very inefficient but is only used by management interfaces. 311 */ 312 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 313 const char *ifname) 314 { 315 struct l2tp_net *pn = l2tp_pernet(net); 316 int hash; 317 struct l2tp_session *session; 318 319 rcu_read_lock_bh(); 320 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { 321 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) { 322 if (!strcmp(session->ifname, ifname)) { 323 l2tp_session_inc_refcount(session); 324 rcu_read_unlock_bh(); 325 326 return session; 327 } 328 } 329 } 330 331 rcu_read_unlock_bh(); 332 333 return NULL; 334 } 335 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); 336 337 int l2tp_session_register(struct l2tp_session *session, 338 struct l2tp_tunnel *tunnel) 339 { 340 struct l2tp_session *session_walk; 341 struct hlist_head *g_head; 342 struct hlist_head *head; 343 struct l2tp_net *pn; 344 int err; 345 346 head = l2tp_session_id_hash(tunnel, session->session_id); 347 348 spin_lock_bh(&tunnel->hlist_lock); 349 if (!tunnel->acpt_newsess) { 350 err = -ENODEV; 351 goto err_tlock; 352 } 353 354 hlist_for_each_entry(session_walk, head, hlist) 355 if (session_walk->session_id == session->session_id) { 356 err = -EEXIST; 357 goto err_tlock; 358 } 359 360 if (tunnel->version == L2TP_HDR_VER_3) { 361 pn = l2tp_pernet(tunnel->l2tp_net); 362 g_head = l2tp_session_id_hash_2(pn, session->session_id); 363 364 spin_lock_bh(&pn->l2tp_session_hlist_lock); 365 366 /* IP encap expects session IDs to be globally unique, while 367 * UDP encap doesn't. 368 */ 369 hlist_for_each_entry(session_walk, g_head, global_hlist) 370 if (session_walk->session_id == session->session_id && 371 (session_walk->tunnel->encap == L2TP_ENCAPTYPE_IP || 372 tunnel->encap == L2TP_ENCAPTYPE_IP)) { 373 err = -EEXIST; 374 goto err_tlock_pnlock; 375 } 376 377 l2tp_tunnel_inc_refcount(tunnel); 378 hlist_add_head_rcu(&session->global_hlist, g_head); 379 380 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 381 } else { 382 l2tp_tunnel_inc_refcount(tunnel); 383 } 384 385 hlist_add_head_rcu(&session->hlist, head); 386 spin_unlock_bh(&tunnel->hlist_lock); 387 388 trace_register_session(session); 389 390 return 0; 391 392 err_tlock_pnlock: 393 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 394 err_tlock: 395 spin_unlock_bh(&tunnel->hlist_lock); 396 397 return err; 398 } 399 EXPORT_SYMBOL_GPL(l2tp_session_register); 400 401 /***************************************************************************** 402 * Receive data handling 403 *****************************************************************************/ 404 405 /* Queue a skb in order. We come here only if the skb has an L2TP sequence 406 * number. 407 */ 408 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb) 409 { 410 struct sk_buff *skbp; 411 struct sk_buff *tmp; 412 u32 ns = L2TP_SKB_CB(skb)->ns; 413 414 spin_lock_bh(&session->reorder_q.lock); 415 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) { 416 if (L2TP_SKB_CB(skbp)->ns > ns) { 417 __skb_queue_before(&session->reorder_q, skbp, skb); 418 atomic_long_inc(&session->stats.rx_oos_packets); 419 goto out; 420 } 421 } 422 423 __skb_queue_tail(&session->reorder_q, skb); 424 425 out: 426 spin_unlock_bh(&session->reorder_q.lock); 427 } 428 429 /* Dequeue a single skb. 430 */ 431 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb) 432 { 433 struct l2tp_tunnel *tunnel = session->tunnel; 434 int length = L2TP_SKB_CB(skb)->length; 435 436 /* We're about to requeue the skb, so return resources 437 * to its current owner (a socket receive buffer). 438 */ 439 skb_orphan(skb); 440 441 atomic_long_inc(&tunnel->stats.rx_packets); 442 atomic_long_add(length, &tunnel->stats.rx_bytes); 443 atomic_long_inc(&session->stats.rx_packets); 444 atomic_long_add(length, &session->stats.rx_bytes); 445 446 if (L2TP_SKB_CB(skb)->has_seq) { 447 /* Bump our Nr */ 448 session->nr++; 449 session->nr &= session->nr_max; 450 trace_session_seqnum_update(session); 451 } 452 453 /* call private receive handler */ 454 if (session->recv_skb) 455 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); 456 else 457 kfree_skb(skb); 458 } 459 460 /* Dequeue skbs from the session's reorder_q, subject to packet order. 461 * Skbs that have been in the queue for too long are simply discarded. 462 */ 463 static void l2tp_recv_dequeue(struct l2tp_session *session) 464 { 465 struct sk_buff *skb; 466 struct sk_buff *tmp; 467 468 /* If the pkt at the head of the queue has the nr that we 469 * expect to send up next, dequeue it and any other 470 * in-sequence packets behind it. 471 */ 472 start: 473 spin_lock_bh(&session->reorder_q.lock); 474 skb_queue_walk_safe(&session->reorder_q, skb, tmp) { 475 struct l2tp_skb_cb *cb = L2TP_SKB_CB(skb); 476 477 /* If the packet has been pending on the queue for too long, discard it */ 478 if (time_after(jiffies, cb->expires)) { 479 atomic_long_inc(&session->stats.rx_seq_discards); 480 atomic_long_inc(&session->stats.rx_errors); 481 trace_session_pkt_expired(session, cb->ns); 482 session->reorder_skip = 1; 483 __skb_unlink(skb, &session->reorder_q); 484 kfree_skb(skb); 485 continue; 486 } 487 488 if (cb->has_seq) { 489 if (session->reorder_skip) { 490 session->reorder_skip = 0; 491 session->nr = cb->ns; 492 trace_session_seqnum_reset(session); 493 } 494 if (cb->ns != session->nr) 495 goto out; 496 } 497 __skb_unlink(skb, &session->reorder_q); 498 499 /* Process the skb. We release the queue lock while we 500 * do so to let other contexts process the queue. 501 */ 502 spin_unlock_bh(&session->reorder_q.lock); 503 l2tp_recv_dequeue_skb(session, skb); 504 goto start; 505 } 506 507 out: 508 spin_unlock_bh(&session->reorder_q.lock); 509 } 510 511 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr) 512 { 513 u32 nws; 514 515 if (nr >= session->nr) 516 nws = nr - session->nr; 517 else 518 nws = (session->nr_max + 1) - (session->nr - nr); 519 520 return nws < session->nr_window_size; 521 } 522 523 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if 524 * acceptable, else non-zero. 525 */ 526 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb) 527 { 528 struct l2tp_skb_cb *cb = L2TP_SKB_CB(skb); 529 530 if (!l2tp_seq_check_rx_window(session, cb->ns)) { 531 /* Packet sequence number is outside allowed window. 532 * Discard it. 533 */ 534 trace_session_pkt_outside_rx_window(session, cb->ns); 535 goto discard; 536 } 537 538 if (session->reorder_timeout != 0) { 539 /* Packet reordering enabled. Add skb to session's 540 * reorder queue, in order of ns. 541 */ 542 l2tp_recv_queue_skb(session, skb); 543 goto out; 544 } 545 546 /* Packet reordering disabled. Discard out-of-sequence packets, while 547 * tracking the number if in-sequence packets after the first OOS packet 548 * is seen. After nr_oos_count_max in-sequence packets, reset the 549 * sequence number to re-enable packet reception. 550 */ 551 if (cb->ns == session->nr) { 552 skb_queue_tail(&session->reorder_q, skb); 553 } else { 554 u32 nr_oos = cb->ns; 555 u32 nr_next = (session->nr_oos + 1) & session->nr_max; 556 557 if (nr_oos == nr_next) 558 session->nr_oos_count++; 559 else 560 session->nr_oos_count = 0; 561 562 session->nr_oos = nr_oos; 563 if (session->nr_oos_count > session->nr_oos_count_max) { 564 session->reorder_skip = 1; 565 } 566 if (!session->reorder_skip) { 567 atomic_long_inc(&session->stats.rx_seq_discards); 568 trace_session_pkt_oos(session, cb->ns); 569 goto discard; 570 } 571 skb_queue_tail(&session->reorder_q, skb); 572 } 573 574 out: 575 return 0; 576 577 discard: 578 return 1; 579 } 580 581 /* Do receive processing of L2TP data frames. We handle both L2TPv2 582 * and L2TPv3 data frames here. 583 * 584 * L2TPv2 Data Message Header 585 * 586 * 0 1 2 3 587 * 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 1 588 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 589 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) | 590 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 591 * | Tunnel ID | Session ID | 592 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 593 * | Ns (opt) | Nr (opt) | 594 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 595 * | Offset Size (opt) | Offset pad... (opt) 596 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 597 * 598 * Data frames are marked by T=0. All other fields are the same as 599 * those in L2TP control frames. 600 * 601 * L2TPv3 Data Message Header 602 * 603 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 604 * | L2TP Session Header | 605 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 606 * | L2-Specific Sublayer | 607 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 608 * | Tunnel Payload ... 609 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 610 * 611 * L2TPv3 Session Header Over IP 612 * 613 * 0 1 2 3 614 * 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 1 615 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 616 * | Session ID | 617 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 618 * | Cookie (optional, maximum 64 bits)... 619 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 620 * | 621 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 622 * 623 * L2TPv3 L2-Specific Sublayer Format 624 * 625 * 0 1 2 3 626 * 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 1 627 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 628 * |x|S|x|x|x|x|x|x| Sequence Number | 629 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 630 * 631 * Cookie value and sublayer format are negotiated with the peer when 632 * the session is set up. Unlike L2TPv2, we do not need to parse the 633 * packet header to determine if optional fields are present. 634 * 635 * Caller must already have parsed the frame and determined that it is 636 * a data (not control) frame before coming here. Fields up to the 637 * session-id have already been parsed and ptr points to the data 638 * after the session-id. 639 */ 640 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 641 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 642 int length) 643 { 644 struct l2tp_tunnel *tunnel = session->tunnel; 645 int offset; 646 647 /* Parse and check optional cookie */ 648 if (session->peer_cookie_len > 0) { 649 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { 650 pr_debug_ratelimited("%s: cookie mismatch (%u/%u). Discarding.\n", 651 tunnel->name, tunnel->tunnel_id, 652 session->session_id); 653 atomic_long_inc(&session->stats.rx_cookie_discards); 654 goto discard; 655 } 656 ptr += session->peer_cookie_len; 657 } 658 659 /* Handle the optional sequence numbers. Sequence numbers are 660 * in different places for L2TPv2 and L2TPv3. 661 * 662 * If we are the LAC, enable/disable sequence numbers under 663 * the control of the LNS. If no sequence numbers present but 664 * we were expecting them, discard frame. 665 */ 666 L2TP_SKB_CB(skb)->has_seq = 0; 667 if (tunnel->version == L2TP_HDR_VER_2) { 668 if (hdrflags & L2TP_HDRFLAG_S) { 669 /* Store L2TP info in the skb */ 670 L2TP_SKB_CB(skb)->ns = ntohs(*(__be16 *)ptr); 671 L2TP_SKB_CB(skb)->has_seq = 1; 672 ptr += 2; 673 /* Skip past nr in the header */ 674 ptr += 2; 675 676 } 677 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 678 u32 l2h = ntohl(*(__be32 *)ptr); 679 680 if (l2h & 0x40000000) { 681 /* Store L2TP info in the skb */ 682 L2TP_SKB_CB(skb)->ns = l2h & 0x00ffffff; 683 L2TP_SKB_CB(skb)->has_seq = 1; 684 } 685 ptr += 4; 686 } 687 688 if (L2TP_SKB_CB(skb)->has_seq) { 689 /* Received a packet with sequence numbers. If we're the LAC, 690 * check if we sre sending sequence numbers and if not, 691 * configure it so. 692 */ 693 if (!session->lns_mode && !session->send_seq) { 694 trace_session_seqnum_lns_enable(session); 695 session->send_seq = 1; 696 l2tp_session_set_header_len(session, tunnel->version); 697 } 698 } else { 699 /* No sequence numbers. 700 * If user has configured mandatory sequence numbers, discard. 701 */ 702 if (session->recv_seq) { 703 pr_debug_ratelimited("%s: recv data has no seq numbers when required. Discarding.\n", 704 session->name); 705 atomic_long_inc(&session->stats.rx_seq_discards); 706 goto discard; 707 } 708 709 /* If we're the LAC and we're sending sequence numbers, the 710 * LNS has requested that we no longer send sequence numbers. 711 * If we're the LNS and we're sending sequence numbers, the 712 * LAC is broken. Discard the frame. 713 */ 714 if (!session->lns_mode && session->send_seq) { 715 trace_session_seqnum_lns_disable(session); 716 session->send_seq = 0; 717 l2tp_session_set_header_len(session, tunnel->version); 718 } else if (session->send_seq) { 719 pr_debug_ratelimited("%s: recv data has no seq numbers when required. Discarding.\n", 720 session->name); 721 atomic_long_inc(&session->stats.rx_seq_discards); 722 goto discard; 723 } 724 } 725 726 /* Session data offset is defined only for L2TPv2 and is 727 * indicated by an optional 16-bit value in the header. 728 */ 729 if (tunnel->version == L2TP_HDR_VER_2) { 730 /* If offset bit set, skip it. */ 731 if (hdrflags & L2TP_HDRFLAG_O) { 732 offset = ntohs(*(__be16 *)ptr); 733 ptr += 2 + offset; 734 } 735 } 736 737 offset = ptr - optr; 738 if (!pskb_may_pull(skb, offset)) 739 goto discard; 740 741 __skb_pull(skb, offset); 742 743 /* Prepare skb for adding to the session's reorder_q. Hold 744 * packets for max reorder_timeout or 1 second if not 745 * reordering. 746 */ 747 L2TP_SKB_CB(skb)->length = length; 748 L2TP_SKB_CB(skb)->expires = jiffies + 749 (session->reorder_timeout ? session->reorder_timeout : HZ); 750 751 /* Add packet to the session's receive queue. Reordering is done here, if 752 * enabled. Saved L2TP protocol info is stored in skb->sb[]. 753 */ 754 if (L2TP_SKB_CB(skb)->has_seq) { 755 if (l2tp_recv_data_seq(session, skb)) 756 goto discard; 757 } else { 758 /* No sequence numbers. Add the skb to the tail of the 759 * reorder queue. This ensures that it will be 760 * delivered after all previous sequenced skbs. 761 */ 762 skb_queue_tail(&session->reorder_q, skb); 763 } 764 765 /* Try to dequeue as many skbs from reorder_q as we can. */ 766 l2tp_recv_dequeue(session); 767 768 return; 769 770 discard: 771 atomic_long_inc(&session->stats.rx_errors); 772 kfree_skb(skb); 773 } 774 EXPORT_SYMBOL_GPL(l2tp_recv_common); 775 776 /* Drop skbs from the session's reorder_q 777 */ 778 static void l2tp_session_queue_purge(struct l2tp_session *session) 779 { 780 struct sk_buff *skb = NULL; 781 782 while ((skb = skb_dequeue(&session->reorder_q))) { 783 atomic_long_inc(&session->stats.rx_errors); 784 kfree_skb(skb); 785 } 786 } 787 788 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame 789 * here. The skb is not on a list when we get here. 790 * Returns 0 if the packet was a data packet and was successfully passed on. 791 * Returns 1 if the packet was not a good data packet and could not be 792 * forwarded. All such packets are passed up to userspace to deal with. 793 */ 794 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb) 795 { 796 struct l2tp_session *session = NULL; 797 struct l2tp_tunnel *orig_tunnel = tunnel; 798 unsigned char *ptr, *optr; 799 u16 hdrflags; 800 u32 tunnel_id, session_id; 801 u16 version; 802 int length; 803 804 /* UDP has verified 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 pr_debug_ratelimited("%s: recv short packet (len=%d)\n", 812 tunnel->name, skb->len); 813 goto invalid; 814 } 815 816 /* Point to L2TP header */ 817 optr = skb->data; 818 ptr = skb->data; 819 820 /* Get L2TP header flags */ 821 hdrflags = ntohs(*(__be16 *)ptr); 822 823 /* Get protocol version */ 824 version = hdrflags & L2TP_HDR_VER_MASK; 825 826 /* Get length of L2TP packet */ 827 length = skb->len; 828 829 /* If type is control packet, it is handled by userspace. */ 830 if (hdrflags & L2TP_HDRFLAG_T) 831 goto pass; 832 833 /* Skip flags */ 834 ptr += 2; 835 836 if (version == L2TP_HDR_VER_2) { 837 /* If length is present, skip it */ 838 if (hdrflags & L2TP_HDRFLAG_L) 839 ptr += 2; 840 841 /* Extract tunnel and session ID */ 842 tunnel_id = ntohs(*(__be16 *)ptr); 843 ptr += 2; 844 845 if (tunnel_id != tunnel->tunnel_id) { 846 /* We are receiving trafic for another tunnel, probably 847 * because we have several tunnels between the same 848 * IP/port quadruple, look it up. 849 */ 850 struct l2tp_tunnel *alt_tunnel; 851 852 alt_tunnel = l2tp_tunnel_get(tunnel->l2tp_net, tunnel_id); 853 if (!alt_tunnel) 854 goto pass; 855 tunnel = alt_tunnel; 856 } 857 858 session_id = ntohs(*(__be16 *)ptr); 859 ptr += 2; 860 } else { 861 ptr += 2; /* skip reserved bits */ 862 tunnel_id = tunnel->tunnel_id; 863 session_id = ntohl(*(__be32 *)ptr); 864 ptr += 4; 865 } 866 867 /* Check protocol version */ 868 if (version != tunnel->version) { 869 pr_debug_ratelimited("%s: recv protocol version mismatch: got %d expected %d\n", 870 tunnel->name, version, tunnel->version); 871 goto invalid; 872 } 873 874 /* Find the session context */ 875 session = l2tp_tunnel_get_session(tunnel, session_id); 876 if (!session || !session->recv_skb) { 877 if (session) 878 l2tp_session_dec_refcount(session); 879 880 /* Not found? Pass to userspace to deal with */ 881 pr_debug_ratelimited("%s: no session found (%u/%u). Passing up.\n", 882 tunnel->name, tunnel_id, session_id); 883 goto pass; 884 } 885 886 if (tunnel->version == L2TP_HDR_VER_3 && 887 l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) { 888 l2tp_session_dec_refcount(session); 889 goto invalid; 890 } 891 892 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length); 893 l2tp_session_dec_refcount(session); 894 895 if (tunnel != orig_tunnel) 896 l2tp_tunnel_dec_refcount(tunnel); 897 898 return 0; 899 900 invalid: 901 atomic_long_inc(&tunnel->stats.rx_invalid); 902 903 pass: 904 /* Put UDP header back */ 905 __skb_push(skb, sizeof(struct udphdr)); 906 907 if (tunnel != orig_tunnel) 908 l2tp_tunnel_dec_refcount(tunnel); 909 910 return 1; 911 } 912 913 /* UDP encapsulation receive handler. See net/ipv4/udp.c. 914 * Return codes: 915 * 0 : success. 916 * <0: error 917 * >0: skb should be passed up to userspace as UDP. 918 */ 919 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 920 { 921 struct l2tp_tunnel *tunnel; 922 923 /* Note that this is called from the encap_rcv hook inside an 924 * RCU-protected region, but without the socket being locked. 925 * Hence we use rcu_dereference_sk_user_data to access the 926 * tunnel data structure rather the usual l2tp_sk_to_tunnel 927 * accessor function. 928 */ 929 tunnel = rcu_dereference_sk_user_data(sk); 930 if (!tunnel) 931 goto pass_up; 932 if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC)) 933 goto pass_up; 934 935 if (l2tp_udp_recv_core(tunnel, skb)) 936 goto pass_up; 937 938 return 0; 939 940 pass_up: 941 return 1; 942 } 943 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 944 945 /************************************************************************ 946 * Transmit handling 947 ***********************************************************************/ 948 949 /* Build an L2TP header for the session into the buffer provided. 950 */ 951 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 952 { 953 struct l2tp_tunnel *tunnel = session->tunnel; 954 __be16 *bufp = buf; 955 __be16 *optr = buf; 956 u16 flags = L2TP_HDR_VER_2; 957 u32 tunnel_id = tunnel->peer_tunnel_id; 958 u32 session_id = session->peer_session_id; 959 960 if (session->send_seq) 961 flags |= L2TP_HDRFLAG_S; 962 963 /* Setup L2TP header. */ 964 *bufp++ = htons(flags); 965 *bufp++ = htons(tunnel_id); 966 *bufp++ = htons(session_id); 967 if (session->send_seq) { 968 *bufp++ = htons(session->ns); 969 *bufp++ = 0; 970 session->ns++; 971 session->ns &= 0xffff; 972 trace_session_seqnum_update(session); 973 } 974 975 return bufp - optr; 976 } 977 978 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 979 { 980 struct l2tp_tunnel *tunnel = session->tunnel; 981 char *bufp = buf; 982 char *optr = bufp; 983 984 /* Setup L2TP header. The header differs slightly for UDP and 985 * IP encapsulations. For UDP, there is 4 bytes of flags. 986 */ 987 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 988 u16 flags = L2TP_HDR_VER_3; 989 *((__be16 *)bufp) = htons(flags); 990 bufp += 2; 991 *((__be16 *)bufp) = 0; 992 bufp += 2; 993 } 994 995 *((__be32 *)bufp) = htonl(session->peer_session_id); 996 bufp += 4; 997 if (session->cookie_len) { 998 memcpy(bufp, &session->cookie[0], session->cookie_len); 999 bufp += session->cookie_len; 1000 } 1001 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 1002 u32 l2h = 0; 1003 1004 if (session->send_seq) { 1005 l2h = 0x40000000 | session->ns; 1006 session->ns++; 1007 session->ns &= 0xffffff; 1008 trace_session_seqnum_update(session); 1009 } 1010 1011 *((__be32 *)bufp) = htonl(l2h); 1012 bufp += 4; 1013 } 1014 1015 return bufp - optr; 1016 } 1017 1018 /* Queue the packet to IP for output: tunnel socket lock must be held */ 1019 static int l2tp_xmit_queue(struct l2tp_tunnel *tunnel, struct sk_buff *skb, struct flowi *fl) 1020 { 1021 int err; 1022 1023 skb->ignore_df = 1; 1024 skb_dst_drop(skb); 1025 #if IS_ENABLED(CONFIG_IPV6) 1026 if (l2tp_sk_is_v6(tunnel->sock)) 1027 err = inet6_csk_xmit(tunnel->sock, skb, NULL); 1028 else 1029 #endif 1030 err = ip_queue_xmit(tunnel->sock, skb, fl); 1031 1032 return err >= 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP; 1033 } 1034 1035 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, unsigned int *len) 1036 { 1037 struct l2tp_tunnel *tunnel = session->tunnel; 1038 unsigned int data_len = skb->len; 1039 struct sock *sk = tunnel->sock; 1040 int headroom, uhlen, udp_len; 1041 int ret = NET_XMIT_SUCCESS; 1042 struct inet_sock *inet; 1043 struct udphdr *uh; 1044 1045 /* Check that there's enough headroom in the skb to insert IP, 1046 * UDP and L2TP headers. If not enough, expand it to 1047 * make room. Adjust truesize. 1048 */ 1049 uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(*uh) : 0; 1050 headroom = NET_SKB_PAD + sizeof(struct iphdr) + uhlen + session->hdr_len; 1051 if (skb_cow_head(skb, headroom)) { 1052 kfree_skb(skb); 1053 return NET_XMIT_DROP; 1054 } 1055 1056 /* Setup L2TP header */ 1057 if (tunnel->version == L2TP_HDR_VER_2) 1058 l2tp_build_l2tpv2_header(session, __skb_push(skb, session->hdr_len)); 1059 else 1060 l2tp_build_l2tpv3_header(session, __skb_push(skb, session->hdr_len)); 1061 1062 /* Reset skb netfilter state */ 1063 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1064 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED); 1065 nf_reset_ct(skb); 1066 1067 bh_lock_sock_nested(sk); 1068 if (sock_owned_by_user(sk)) { 1069 kfree_skb(skb); 1070 ret = NET_XMIT_DROP; 1071 goto out_unlock; 1072 } 1073 1074 /* The user-space may change the connection status for the user-space 1075 * provided socket at run time: we must check it under the socket lock 1076 */ 1077 if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) { 1078 kfree_skb(skb); 1079 ret = NET_XMIT_DROP; 1080 goto out_unlock; 1081 } 1082 1083 /* Report transmitted length before we add encap header, which keeps 1084 * statistics consistent for both UDP and IP encap tx/rx paths. 1085 */ 1086 *len = skb->len; 1087 1088 inet = inet_sk(sk); 1089 switch (tunnel->encap) { 1090 case L2TP_ENCAPTYPE_UDP: 1091 /* Setup UDP header */ 1092 __skb_push(skb, sizeof(*uh)); 1093 skb_reset_transport_header(skb); 1094 uh = udp_hdr(skb); 1095 uh->source = inet->inet_sport; 1096 uh->dest = inet->inet_dport; 1097 udp_len = uhlen + session->hdr_len + data_len; 1098 uh->len = htons(udp_len); 1099 1100 /* Calculate UDP checksum if configured to do so */ 1101 #if IS_ENABLED(CONFIG_IPV6) 1102 if (l2tp_sk_is_v6(sk)) 1103 udp6_set_csum(udp_get_no_check6_tx(sk), 1104 skb, &inet6_sk(sk)->saddr, 1105 &sk->sk_v6_daddr, udp_len); 1106 else 1107 #endif 1108 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr, 1109 inet->inet_daddr, udp_len); 1110 break; 1111 1112 case L2TP_ENCAPTYPE_IP: 1113 break; 1114 } 1115 1116 ret = l2tp_xmit_queue(tunnel, skb, &inet->cork.fl); 1117 1118 out_unlock: 1119 bh_unlock_sock(sk); 1120 1121 return ret; 1122 } 1123 1124 /* If caller requires the skb to have a ppp header, the header must be 1125 * inserted in the skb data before calling this function. 1126 */ 1127 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb) 1128 { 1129 unsigned int len = 0; 1130 int ret; 1131 1132 ret = l2tp_xmit_core(session, skb, &len); 1133 if (ret == NET_XMIT_SUCCESS) { 1134 atomic_long_inc(&session->tunnel->stats.tx_packets); 1135 atomic_long_add(len, &session->tunnel->stats.tx_bytes); 1136 atomic_long_inc(&session->stats.tx_packets); 1137 atomic_long_add(len, &session->stats.tx_bytes); 1138 } else { 1139 atomic_long_inc(&session->tunnel->stats.tx_errors); 1140 atomic_long_inc(&session->stats.tx_errors); 1141 } 1142 return ret; 1143 } 1144 EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1145 1146 /***************************************************************************** 1147 * Tinnel and session create/destroy. 1148 *****************************************************************************/ 1149 1150 /* Tunnel socket destruct hook. 1151 * The tunnel context is deleted only when all session sockets have been 1152 * closed. 1153 */ 1154 static void l2tp_tunnel_destruct(struct sock *sk) 1155 { 1156 struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk); 1157 1158 if (!tunnel) 1159 goto end; 1160 1161 /* Disable udp encapsulation */ 1162 switch (tunnel->encap) { 1163 case L2TP_ENCAPTYPE_UDP: 1164 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1165 WRITE_ONCE(udp_sk(sk)->encap_type, 0); 1166 udp_sk(sk)->encap_rcv = NULL; 1167 udp_sk(sk)->encap_destroy = NULL; 1168 break; 1169 case L2TP_ENCAPTYPE_IP: 1170 break; 1171 } 1172 1173 /* Remove hooks into tunnel socket */ 1174 write_lock_bh(&sk->sk_callback_lock); 1175 sk->sk_destruct = tunnel->old_sk_destruct; 1176 sk->sk_user_data = NULL; 1177 write_unlock_bh(&sk->sk_callback_lock); 1178 1179 /* Call the original destructor */ 1180 if (sk->sk_destruct) 1181 (*sk->sk_destruct)(sk); 1182 1183 kfree_rcu(tunnel, rcu); 1184 end: 1185 return; 1186 } 1187 1188 /* Remove an l2tp session from l2tp_core's hash lists. */ 1189 static void l2tp_session_unhash(struct l2tp_session *session) 1190 { 1191 struct l2tp_tunnel *tunnel = session->tunnel; 1192 1193 /* Remove the session from core hashes */ 1194 if (tunnel) { 1195 /* Remove from the per-tunnel hash */ 1196 spin_lock_bh(&tunnel->hlist_lock); 1197 hlist_del_init_rcu(&session->hlist); 1198 spin_unlock_bh(&tunnel->hlist_lock); 1199 1200 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1201 if (tunnel->version != L2TP_HDR_VER_2) { 1202 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1203 1204 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1205 hlist_del_init_rcu(&session->global_hlist); 1206 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1207 } 1208 1209 synchronize_rcu(); 1210 } 1211 } 1212 1213 /* When the tunnel is closed, all the attached sessions need to go too. 1214 */ 1215 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1216 { 1217 struct l2tp_session *session; 1218 int hash; 1219 1220 spin_lock_bh(&tunnel->hlist_lock); 1221 tunnel->acpt_newsess = false; 1222 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1223 again: 1224 hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) { 1225 hlist_del_init_rcu(&session->hlist); 1226 1227 spin_unlock_bh(&tunnel->hlist_lock); 1228 l2tp_session_delete(session); 1229 spin_lock_bh(&tunnel->hlist_lock); 1230 1231 /* Now restart from the beginning of this hash 1232 * chain. We always remove a session from the 1233 * list so we are guaranteed to make forward 1234 * progress. 1235 */ 1236 goto again; 1237 } 1238 } 1239 spin_unlock_bh(&tunnel->hlist_lock); 1240 } 1241 1242 /* Tunnel socket destroy hook for UDP encapsulation */ 1243 static void l2tp_udp_encap_destroy(struct sock *sk) 1244 { 1245 struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk); 1246 1247 if (tunnel) 1248 l2tp_tunnel_delete(tunnel); 1249 } 1250 1251 static void l2tp_tunnel_remove(struct net *net, struct l2tp_tunnel *tunnel) 1252 { 1253 struct l2tp_net *pn = l2tp_pernet(net); 1254 1255 spin_lock_bh(&pn->l2tp_tunnel_idr_lock); 1256 idr_remove(&pn->l2tp_tunnel_idr, tunnel->tunnel_id); 1257 spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); 1258 } 1259 1260 /* Workqueue tunnel deletion function */ 1261 static void l2tp_tunnel_del_work(struct work_struct *work) 1262 { 1263 struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, 1264 del_work); 1265 struct sock *sk = tunnel->sock; 1266 struct socket *sock = sk->sk_socket; 1267 1268 l2tp_tunnel_closeall(tunnel); 1269 1270 /* If the tunnel socket was created within the kernel, use 1271 * the sk API to release it here. 1272 */ 1273 if (tunnel->fd < 0) { 1274 if (sock) { 1275 kernel_sock_shutdown(sock, SHUT_RDWR); 1276 sock_release(sock); 1277 } 1278 } 1279 1280 l2tp_tunnel_remove(tunnel->l2tp_net, tunnel); 1281 /* drop initial ref */ 1282 l2tp_tunnel_dec_refcount(tunnel); 1283 1284 /* drop workqueue ref */ 1285 l2tp_tunnel_dec_refcount(tunnel); 1286 } 1287 1288 /* Create a socket for the tunnel, if one isn't set up by 1289 * userspace. This is used for static tunnels where there is no 1290 * managing L2TP daemon. 1291 * 1292 * Since we don't want these sockets to keep a namespace alive by 1293 * themselves, we drop the socket's namespace refcount after creation. 1294 * These sockets are freed when the namespace exits using the pernet 1295 * exit hook. 1296 */ 1297 static int l2tp_tunnel_sock_create(struct net *net, 1298 u32 tunnel_id, 1299 u32 peer_tunnel_id, 1300 struct l2tp_tunnel_cfg *cfg, 1301 struct socket **sockp) 1302 { 1303 int err = -EINVAL; 1304 struct socket *sock = NULL; 1305 struct udp_port_cfg udp_conf; 1306 1307 switch (cfg->encap) { 1308 case L2TP_ENCAPTYPE_UDP: 1309 memset(&udp_conf, 0, sizeof(udp_conf)); 1310 1311 #if IS_ENABLED(CONFIG_IPV6) 1312 if (cfg->local_ip6 && cfg->peer_ip6) { 1313 udp_conf.family = AF_INET6; 1314 memcpy(&udp_conf.local_ip6, cfg->local_ip6, 1315 sizeof(udp_conf.local_ip6)); 1316 memcpy(&udp_conf.peer_ip6, cfg->peer_ip6, 1317 sizeof(udp_conf.peer_ip6)); 1318 udp_conf.use_udp6_tx_checksums = 1319 !cfg->udp6_zero_tx_checksums; 1320 udp_conf.use_udp6_rx_checksums = 1321 !cfg->udp6_zero_rx_checksums; 1322 } else 1323 #endif 1324 { 1325 udp_conf.family = AF_INET; 1326 udp_conf.local_ip = cfg->local_ip; 1327 udp_conf.peer_ip = cfg->peer_ip; 1328 udp_conf.use_udp_checksums = cfg->use_udp_checksums; 1329 } 1330 1331 udp_conf.local_udp_port = htons(cfg->local_udp_port); 1332 udp_conf.peer_udp_port = htons(cfg->peer_udp_port); 1333 1334 err = udp_sock_create(net, &udp_conf, &sock); 1335 if (err < 0) 1336 goto out; 1337 1338 break; 1339 1340 case L2TP_ENCAPTYPE_IP: 1341 #if IS_ENABLED(CONFIG_IPV6) 1342 if (cfg->local_ip6 && cfg->peer_ip6) { 1343 struct sockaddr_l2tpip6 ip6_addr = {0}; 1344 1345 err = sock_create_kern(net, AF_INET6, SOCK_DGRAM, 1346 IPPROTO_L2TP, &sock); 1347 if (err < 0) 1348 goto out; 1349 1350 ip6_addr.l2tp_family = AF_INET6; 1351 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6, 1352 sizeof(ip6_addr.l2tp_addr)); 1353 ip6_addr.l2tp_conn_id = tunnel_id; 1354 err = kernel_bind(sock, (struct sockaddr *)&ip6_addr, 1355 sizeof(ip6_addr)); 1356 if (err < 0) 1357 goto out; 1358 1359 ip6_addr.l2tp_family = AF_INET6; 1360 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6, 1361 sizeof(ip6_addr.l2tp_addr)); 1362 ip6_addr.l2tp_conn_id = peer_tunnel_id; 1363 err = kernel_connect(sock, 1364 (struct sockaddr *)&ip6_addr, 1365 sizeof(ip6_addr), 0); 1366 if (err < 0) 1367 goto out; 1368 } else 1369 #endif 1370 { 1371 struct sockaddr_l2tpip ip_addr = {0}; 1372 1373 err = sock_create_kern(net, AF_INET, SOCK_DGRAM, 1374 IPPROTO_L2TP, &sock); 1375 if (err < 0) 1376 goto out; 1377 1378 ip_addr.l2tp_family = AF_INET; 1379 ip_addr.l2tp_addr = cfg->local_ip; 1380 ip_addr.l2tp_conn_id = tunnel_id; 1381 err = kernel_bind(sock, (struct sockaddr *)&ip_addr, 1382 sizeof(ip_addr)); 1383 if (err < 0) 1384 goto out; 1385 1386 ip_addr.l2tp_family = AF_INET; 1387 ip_addr.l2tp_addr = cfg->peer_ip; 1388 ip_addr.l2tp_conn_id = peer_tunnel_id; 1389 err = kernel_connect(sock, (struct sockaddr *)&ip_addr, 1390 sizeof(ip_addr), 0); 1391 if (err < 0) 1392 goto out; 1393 } 1394 break; 1395 1396 default: 1397 goto out; 1398 } 1399 1400 out: 1401 *sockp = sock; 1402 if (err < 0 && sock) { 1403 kernel_sock_shutdown(sock, SHUT_RDWR); 1404 sock_release(sock); 1405 *sockp = NULL; 1406 } 1407 1408 return err; 1409 } 1410 1411 int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, 1412 struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp) 1413 { 1414 struct l2tp_tunnel *tunnel = NULL; 1415 int err; 1416 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1417 1418 if (cfg) 1419 encap = cfg->encap; 1420 1421 tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL); 1422 if (!tunnel) { 1423 err = -ENOMEM; 1424 goto err; 1425 } 1426 1427 tunnel->version = version; 1428 tunnel->tunnel_id = tunnel_id; 1429 tunnel->peer_tunnel_id = peer_tunnel_id; 1430 1431 tunnel->magic = L2TP_TUNNEL_MAGIC; 1432 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1433 spin_lock_init(&tunnel->hlist_lock); 1434 tunnel->acpt_newsess = true; 1435 1436 tunnel->encap = encap; 1437 1438 refcount_set(&tunnel->ref_count, 1); 1439 tunnel->fd = fd; 1440 1441 /* Init delete workqueue struct */ 1442 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); 1443 1444 INIT_LIST_HEAD(&tunnel->list); 1445 1446 err = 0; 1447 err: 1448 if (tunnelp) 1449 *tunnelp = tunnel; 1450 1451 return err; 1452 } 1453 EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1454 1455 static int l2tp_validate_socket(const struct sock *sk, const struct net *net, 1456 enum l2tp_encap_type encap) 1457 { 1458 if (!net_eq(sock_net(sk), net)) 1459 return -EINVAL; 1460 1461 if (sk->sk_type != SOCK_DGRAM) 1462 return -EPROTONOSUPPORT; 1463 1464 if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6) 1465 return -EPROTONOSUPPORT; 1466 1467 if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) || 1468 (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP)) 1469 return -EPROTONOSUPPORT; 1470 1471 if (sk->sk_user_data) 1472 return -EBUSY; 1473 1474 return 0; 1475 } 1476 1477 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 1478 struct l2tp_tunnel_cfg *cfg) 1479 { 1480 struct l2tp_net *pn = l2tp_pernet(net); 1481 u32 tunnel_id = tunnel->tunnel_id; 1482 struct socket *sock; 1483 struct sock *sk; 1484 int ret; 1485 1486 spin_lock_bh(&pn->l2tp_tunnel_idr_lock); 1487 ret = idr_alloc_u32(&pn->l2tp_tunnel_idr, NULL, &tunnel_id, tunnel_id, 1488 GFP_ATOMIC); 1489 spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); 1490 if (ret) 1491 return ret == -ENOSPC ? -EEXIST : ret; 1492 1493 if (tunnel->fd < 0) { 1494 ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id, 1495 tunnel->peer_tunnel_id, cfg, 1496 &sock); 1497 if (ret < 0) 1498 goto err; 1499 } else { 1500 sock = sockfd_lookup(tunnel->fd, &ret); 1501 if (!sock) 1502 goto err; 1503 } 1504 1505 sk = sock->sk; 1506 lock_sock(sk); 1507 write_lock_bh(&sk->sk_callback_lock); 1508 ret = l2tp_validate_socket(sk, net, tunnel->encap); 1509 if (ret < 0) 1510 goto err_inval_sock; 1511 rcu_assign_sk_user_data(sk, tunnel); 1512 write_unlock_bh(&sk->sk_callback_lock); 1513 1514 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1515 struct udp_tunnel_sock_cfg udp_cfg = { 1516 .sk_user_data = tunnel, 1517 .encap_type = UDP_ENCAP_L2TPINUDP, 1518 .encap_rcv = l2tp_udp_encap_recv, 1519 .encap_destroy = l2tp_udp_encap_destroy, 1520 }; 1521 1522 setup_udp_tunnel_sock(net, sock, &udp_cfg); 1523 } 1524 1525 tunnel->old_sk_destruct = sk->sk_destruct; 1526 sk->sk_destruct = &l2tp_tunnel_destruct; 1527 sk->sk_allocation = GFP_ATOMIC; 1528 release_sock(sk); 1529 1530 sock_hold(sk); 1531 tunnel->sock = sk; 1532 tunnel->l2tp_net = net; 1533 1534 spin_lock_bh(&pn->l2tp_tunnel_idr_lock); 1535 idr_replace(&pn->l2tp_tunnel_idr, tunnel, tunnel->tunnel_id); 1536 spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); 1537 1538 trace_register_tunnel(tunnel); 1539 1540 if (tunnel->fd >= 0) 1541 sockfd_put(sock); 1542 1543 return 0; 1544 1545 err_inval_sock: 1546 write_unlock_bh(&sk->sk_callback_lock); 1547 release_sock(sk); 1548 1549 if (tunnel->fd < 0) 1550 sock_release(sock); 1551 else 1552 sockfd_put(sock); 1553 err: 1554 l2tp_tunnel_remove(net, tunnel); 1555 return ret; 1556 } 1557 EXPORT_SYMBOL_GPL(l2tp_tunnel_register); 1558 1559 /* This function is used by the netlink TUNNEL_DELETE command. 1560 */ 1561 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1562 { 1563 if (!test_and_set_bit(0, &tunnel->dead)) { 1564 trace_delete_tunnel(tunnel); 1565 l2tp_tunnel_inc_refcount(tunnel); 1566 queue_work(l2tp_wq, &tunnel->del_work); 1567 } 1568 } 1569 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1570 1571 void l2tp_session_delete(struct l2tp_session *session) 1572 { 1573 if (test_and_set_bit(0, &session->dead)) 1574 return; 1575 1576 trace_delete_session(session); 1577 l2tp_session_unhash(session); 1578 l2tp_session_queue_purge(session); 1579 if (session->session_close) 1580 (*session->session_close)(session); 1581 1582 l2tp_session_dec_refcount(session); 1583 } 1584 EXPORT_SYMBOL_GPL(l2tp_session_delete); 1585 1586 /* We come here whenever a session's send_seq, cookie_len or 1587 * l2specific_type parameters are set. 1588 */ 1589 void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1590 { 1591 if (version == L2TP_HDR_VER_2) { 1592 session->hdr_len = 6; 1593 if (session->send_seq) 1594 session->hdr_len += 4; 1595 } else { 1596 session->hdr_len = 4 + session->cookie_len; 1597 session->hdr_len += l2tp_get_l2specific_len(session); 1598 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1599 session->hdr_len += 4; 1600 } 1601 } 1602 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1603 1604 struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, 1605 u32 peer_session_id, struct l2tp_session_cfg *cfg) 1606 { 1607 struct l2tp_session *session; 1608 1609 session = kzalloc(sizeof(*session) + priv_size, GFP_KERNEL); 1610 if (session) { 1611 session->magic = L2TP_SESSION_MAGIC; 1612 session->tunnel = tunnel; 1613 1614 session->session_id = session_id; 1615 session->peer_session_id = peer_session_id; 1616 session->nr = 0; 1617 if (tunnel->version == L2TP_HDR_VER_2) 1618 session->nr_max = 0xffff; 1619 else 1620 session->nr_max = 0xffffff; 1621 session->nr_window_size = session->nr_max / 2; 1622 session->nr_oos_count_max = 4; 1623 1624 /* Use NR of first received packet */ 1625 session->reorder_skip = 1; 1626 1627 sprintf(&session->name[0], "sess %u/%u", 1628 tunnel->tunnel_id, session->session_id); 1629 1630 skb_queue_head_init(&session->reorder_q); 1631 1632 INIT_HLIST_NODE(&session->hlist); 1633 INIT_HLIST_NODE(&session->global_hlist); 1634 1635 if (cfg) { 1636 session->pwtype = cfg->pw_type; 1637 session->send_seq = cfg->send_seq; 1638 session->recv_seq = cfg->recv_seq; 1639 session->lns_mode = cfg->lns_mode; 1640 session->reorder_timeout = cfg->reorder_timeout; 1641 session->l2specific_type = cfg->l2specific_type; 1642 session->cookie_len = cfg->cookie_len; 1643 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1644 session->peer_cookie_len = cfg->peer_cookie_len; 1645 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1646 } 1647 1648 l2tp_session_set_header_len(session, tunnel->version); 1649 1650 refcount_set(&session->ref_count, 1); 1651 1652 return session; 1653 } 1654 1655 return ERR_PTR(-ENOMEM); 1656 } 1657 EXPORT_SYMBOL_GPL(l2tp_session_create); 1658 1659 /***************************************************************************** 1660 * Init and cleanup 1661 *****************************************************************************/ 1662 1663 static __net_init int l2tp_init_net(struct net *net) 1664 { 1665 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1666 int hash; 1667 1668 idr_init(&pn->l2tp_tunnel_idr); 1669 spin_lock_init(&pn->l2tp_tunnel_idr_lock); 1670 1671 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1672 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1673 1674 spin_lock_init(&pn->l2tp_session_hlist_lock); 1675 1676 return 0; 1677 } 1678 1679 static __net_exit void l2tp_exit_net(struct net *net) 1680 { 1681 struct l2tp_net *pn = l2tp_pernet(net); 1682 struct l2tp_tunnel *tunnel = NULL; 1683 unsigned long tunnel_id, tmp; 1684 int hash; 1685 1686 rcu_read_lock_bh(); 1687 idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) { 1688 if (tunnel) 1689 l2tp_tunnel_delete(tunnel); 1690 } 1691 rcu_read_unlock_bh(); 1692 1693 if (l2tp_wq) 1694 flush_workqueue(l2tp_wq); 1695 rcu_barrier(); 1696 1697 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1698 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); 1699 idr_destroy(&pn->l2tp_tunnel_idr); 1700 } 1701 1702 static struct pernet_operations l2tp_net_ops = { 1703 .init = l2tp_init_net, 1704 .exit = l2tp_exit_net, 1705 .id = &l2tp_net_id, 1706 .size = sizeof(struct l2tp_net), 1707 }; 1708 1709 static int __init l2tp_init(void) 1710 { 1711 int rc = 0; 1712 1713 rc = register_pernet_device(&l2tp_net_ops); 1714 if (rc) 1715 goto out; 1716 1717 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1718 if (!l2tp_wq) { 1719 pr_err("alloc_workqueue failed\n"); 1720 unregister_pernet_device(&l2tp_net_ops); 1721 rc = -ENOMEM; 1722 goto out; 1723 } 1724 1725 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 1726 1727 out: 1728 return rc; 1729 } 1730 1731 static void __exit l2tp_exit(void) 1732 { 1733 unregister_pernet_device(&l2tp_net_ops); 1734 if (l2tp_wq) { 1735 destroy_workqueue(l2tp_wq); 1736 l2tp_wq = NULL; 1737 } 1738 } 1739 1740 module_init(l2tp_init); 1741 module_exit(l2tp_exit); 1742 1743 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1744 MODULE_DESCRIPTION("L2TP core"); 1745 MODULE_LICENSE("GPL"); 1746 MODULE_VERSION(L2TP_DRV_VERSION); 1747