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 */ 93struct 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 102static struct workqueue_struct *l2tp_wq; 103 104/* per-net private data for this module */ 105static unsigned int l2tp_net_id; 106struct 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) 116static 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 123static 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 */ 133static inline struct hlist_head * 134l2tp_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 */ 145static inline struct hlist_head * 146l2tp_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 151static 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 158static 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 166struct 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} 176EXPORT_SYMBOL_GPL(l2tp_sk_to_tunnel); 177 178void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel) 179{ 180 refcount_inc(&tunnel->ref_count); 181} 182EXPORT_SYMBOL_GPL(l2tp_tunnel_inc_refcount); 183 184void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel) 185{ 186 if (refcount_dec_and_test(&tunnel->ref_count)) 187 l2tp_tunnel_free(tunnel); 188} 189EXPORT_SYMBOL_GPL(l2tp_tunnel_dec_refcount); 190 191void l2tp_session_inc_refcount(struct l2tp_session *session) 192{ 193 refcount_inc(&session->ref_count); 194} 195EXPORT_SYMBOL_GPL(l2tp_session_inc_refcount); 196 197void l2tp_session_dec_refcount(struct l2tp_session *session) 198{ 199 if (refcount_dec_and_test(&session->ref_count)) 200 l2tp_session_free(session); 201} 202EXPORT_SYMBOL_GPL(l2tp_session_dec_refcount); 203 204/* Lookup a tunnel. A new reference is held on the returned tunnel. */ 205struct 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} 220EXPORT_SYMBOL_GPL(l2tp_tunnel_get); 221 222struct 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} 241EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth); 242 243struct 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} 263EXPORT_SYMBOL_GPL(l2tp_tunnel_get_session); 264 265struct 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} 284EXPORT_SYMBOL_GPL(l2tp_session_get); 285 286struct 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} 307EXPORT_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 */ 312struct 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} 335EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); 336 337int 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 392err_tlock_pnlock: 393 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 394err_tlock: 395 spin_unlock_bh(&tunnel->hlist_lock); 396 397 return err; 398} 399EXPORT_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 */ 408static 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 425out: 426 spin_unlock_bh(&session->reorder_q.lock); 427} 428 429/* Dequeue a single skb. 430 */ 431static 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 */ 463static 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 */ 472start: 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 507out: 508 spin_unlock_bh(&session->reorder_q.lock); 509} 510 511static 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 */ 526static 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 574out: 575 return 0; 576 577discard: 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 */ 640void 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 770discard: 771 atomic_long_inc(&session->stats.rx_errors); 772 kfree_skb(skb); 773} 774EXPORT_SYMBOL_GPL(l2tp_recv_common); 775 776/* Drop skbs from the session's reorder_q 777 */ 778static 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 */ 794static 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 900invalid: 901 atomic_long_inc(&tunnel->stats.rx_invalid); 902 903pass: 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 and error receive handlers. 914 * See net/ipv4/udp.c for details. 915 * 916 * Note that these functions are called from inside an 917 * RCU-protected region, but without the socket being locked. 918 * 919 * Hence we use rcu_dereference_sk_user_data to access the 920 * tunnel data structure rather the usual l2tp_sk_to_tunnel 921 * accessor function. 922 */ 923int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 924{ 925 struct l2tp_tunnel *tunnel; 926 927 tunnel = rcu_dereference_sk_user_data(sk); 928 if (!tunnel) 929 goto pass_up; 930 if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC)) 931 goto pass_up; 932 933 if (l2tp_udp_recv_core(tunnel, skb)) 934 goto pass_up; 935 936 return 0; 937 938pass_up: 939 return 1; 940} 941EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 942 943static void l2tp_udp_encap_err_recv(struct sock *sk, struct sk_buff *skb, int err, 944 __be16 port, u32 info, u8 *payload) 945{ 946 struct l2tp_tunnel *tunnel; 947 948 tunnel = rcu_dereference_sk_user_data(sk); 949 if (!tunnel || tunnel->fd < 0) 950 return; 951 952 sk->sk_err = err; 953 sk_error_report(sk); 954 955 if (ip_hdr(skb)->version == IPVERSION) { 956 if (inet_test_bit(RECVERR, sk)) 957 return ip_icmp_error(sk, skb, err, port, info, payload); 958#if IS_ENABLED(CONFIG_IPV6) 959 } else { 960 if (inet6_test_bit(RECVERR6, sk)) 961 return ipv6_icmp_error(sk, skb, err, port, info, payload); 962#endif 963 } 964} 965 966/************************************************************************ 967 * Transmit handling 968 ***********************************************************************/ 969 970/* Build an L2TP header for the session into the buffer provided. 971 */ 972static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 973{ 974 struct l2tp_tunnel *tunnel = session->tunnel; 975 __be16 *bufp = buf; 976 __be16 *optr = buf; 977 u16 flags = L2TP_HDR_VER_2; 978 u32 tunnel_id = tunnel->peer_tunnel_id; 979 u32 session_id = session->peer_session_id; 980 981 if (session->send_seq) 982 flags |= L2TP_HDRFLAG_S; 983 984 /* Setup L2TP header. */ 985 *bufp++ = htons(flags); 986 *bufp++ = htons(tunnel_id); 987 *bufp++ = htons(session_id); 988 if (session->send_seq) { 989 *bufp++ = htons(session->ns); 990 *bufp++ = 0; 991 session->ns++; 992 session->ns &= 0xffff; 993 trace_session_seqnum_update(session); 994 } 995 996 return bufp - optr; 997} 998 999static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 1000{ 1001 struct l2tp_tunnel *tunnel = session->tunnel; 1002 char *bufp = buf; 1003 char *optr = bufp; 1004 1005 /* Setup L2TP header. The header differs slightly for UDP and 1006 * IP encapsulations. For UDP, there is 4 bytes of flags. 1007 */ 1008 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1009 u16 flags = L2TP_HDR_VER_3; 1010 *((__be16 *)bufp) = htons(flags); 1011 bufp += 2; 1012 *((__be16 *)bufp) = 0; 1013 bufp += 2; 1014 } 1015 1016 *((__be32 *)bufp) = htonl(session->peer_session_id); 1017 bufp += 4; 1018 if (session->cookie_len) { 1019 memcpy(bufp, &session->cookie[0], session->cookie_len); 1020 bufp += session->cookie_len; 1021 } 1022 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 1023 u32 l2h = 0; 1024 1025 if (session->send_seq) { 1026 l2h = 0x40000000 | session->ns; 1027 session->ns++; 1028 session->ns &= 0xffffff; 1029 trace_session_seqnum_update(session); 1030 } 1031 1032 *((__be32 *)bufp) = htonl(l2h); 1033 bufp += 4; 1034 } 1035 1036 return bufp - optr; 1037} 1038 1039/* Queue the packet to IP for output: tunnel socket lock must be held */ 1040static int l2tp_xmit_queue(struct l2tp_tunnel *tunnel, struct sk_buff *skb, struct flowi *fl) 1041{ 1042 int err; 1043 1044 skb->ignore_df = 1; 1045 skb_dst_drop(skb); 1046#if IS_ENABLED(CONFIG_IPV6) 1047 if (l2tp_sk_is_v6(tunnel->sock)) 1048 err = inet6_csk_xmit(tunnel->sock, skb, NULL); 1049 else 1050#endif 1051 err = ip_queue_xmit(tunnel->sock, skb, fl); 1052 1053 return err >= 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP; 1054} 1055 1056static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, unsigned int *len) 1057{ 1058 struct l2tp_tunnel *tunnel = session->tunnel; 1059 unsigned int data_len = skb->len; 1060 struct sock *sk = tunnel->sock; 1061 int headroom, uhlen, udp_len; 1062 int ret = NET_XMIT_SUCCESS; 1063 struct inet_sock *inet; 1064 struct udphdr *uh; 1065 1066 /* Check that there's enough headroom in the skb to insert IP, 1067 * UDP and L2TP headers. If not enough, expand it to 1068 * make room. Adjust truesize. 1069 */ 1070 uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(*uh) : 0; 1071 headroom = NET_SKB_PAD + sizeof(struct iphdr) + uhlen + session->hdr_len; 1072 if (skb_cow_head(skb, headroom)) { 1073 kfree_skb(skb); 1074 return NET_XMIT_DROP; 1075 } 1076 1077 /* Setup L2TP header */ 1078 if (tunnel->version == L2TP_HDR_VER_2) 1079 l2tp_build_l2tpv2_header(session, __skb_push(skb, session->hdr_len)); 1080 else 1081 l2tp_build_l2tpv3_header(session, __skb_push(skb, session->hdr_len)); 1082 1083 /* Reset skb netfilter state */ 1084 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1085 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED); 1086 nf_reset_ct(skb); 1087 1088 bh_lock_sock_nested(sk); 1089 if (sock_owned_by_user(sk)) { 1090 kfree_skb(skb); 1091 ret = NET_XMIT_DROP; 1092 goto out_unlock; 1093 } 1094 1095 /* The user-space may change the connection status for the user-space 1096 * provided socket at run time: we must check it under the socket lock 1097 */ 1098 if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) { 1099 kfree_skb(skb); 1100 ret = NET_XMIT_DROP; 1101 goto out_unlock; 1102 } 1103 1104 /* Report transmitted length before we add encap header, which keeps 1105 * statistics consistent for both UDP and IP encap tx/rx paths. 1106 */ 1107 *len = skb->len; 1108 1109 inet = inet_sk(sk); 1110 switch (tunnel->encap) { 1111 case L2TP_ENCAPTYPE_UDP: 1112 /* Setup UDP header */ 1113 __skb_push(skb, sizeof(*uh)); 1114 skb_reset_transport_header(skb); 1115 uh = udp_hdr(skb); 1116 uh->source = inet->inet_sport; 1117 uh->dest = inet->inet_dport; 1118 udp_len = uhlen + session->hdr_len + data_len; 1119 uh->len = htons(udp_len); 1120 1121 /* Calculate UDP checksum if configured to do so */ 1122#if IS_ENABLED(CONFIG_IPV6) 1123 if (l2tp_sk_is_v6(sk)) 1124 udp6_set_csum(udp_get_no_check6_tx(sk), 1125 skb, &inet6_sk(sk)->saddr, 1126 &sk->sk_v6_daddr, udp_len); 1127 else 1128#endif 1129 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr, 1130 inet->inet_daddr, udp_len); 1131 break; 1132 1133 case L2TP_ENCAPTYPE_IP: 1134 break; 1135 } 1136 1137 ret = l2tp_xmit_queue(tunnel, skb, &inet->cork.fl); 1138 1139out_unlock: 1140 bh_unlock_sock(sk); 1141 1142 return ret; 1143} 1144 1145/* If caller requires the skb to have a ppp header, the header must be 1146 * inserted in the skb data before calling this function. 1147 */ 1148int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb) 1149{ 1150 unsigned int len = 0; 1151 int ret; 1152 1153 ret = l2tp_xmit_core(session, skb, &len); 1154 if (ret == NET_XMIT_SUCCESS) { 1155 atomic_long_inc(&session->tunnel->stats.tx_packets); 1156 atomic_long_add(len, &session->tunnel->stats.tx_bytes); 1157 atomic_long_inc(&session->stats.tx_packets); 1158 atomic_long_add(len, &session->stats.tx_bytes); 1159 } else { 1160 atomic_long_inc(&session->tunnel->stats.tx_errors); 1161 atomic_long_inc(&session->stats.tx_errors); 1162 } 1163 return ret; 1164} 1165EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1166 1167/***************************************************************************** 1168 * Tinnel and session create/destroy. 1169 *****************************************************************************/ 1170 1171/* Tunnel socket destruct hook. 1172 * The tunnel context is deleted only when all session sockets have been 1173 * closed. 1174 */ 1175static void l2tp_tunnel_destruct(struct sock *sk) 1176{ 1177 struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk); 1178 1179 if (!tunnel) 1180 goto end; 1181 1182 /* Disable udp encapsulation */ 1183 switch (tunnel->encap) { 1184 case L2TP_ENCAPTYPE_UDP: 1185 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1186 WRITE_ONCE(udp_sk(sk)->encap_type, 0); 1187 udp_sk(sk)->encap_rcv = NULL; 1188 udp_sk(sk)->encap_destroy = NULL; 1189 break; 1190 case L2TP_ENCAPTYPE_IP: 1191 break; 1192 } 1193 1194 /* Remove hooks into tunnel socket */ 1195 write_lock_bh(&sk->sk_callback_lock); 1196 sk->sk_destruct = tunnel->old_sk_destruct; 1197 sk->sk_user_data = NULL; 1198 write_unlock_bh(&sk->sk_callback_lock); 1199 1200 /* Call the original destructor */ 1201 if (sk->sk_destruct) 1202 (*sk->sk_destruct)(sk); 1203 1204 kfree_rcu(tunnel, rcu); 1205end: 1206 return; 1207} 1208 1209/* Remove an l2tp session from l2tp_core's hash lists. */ 1210static void l2tp_session_unhash(struct l2tp_session *session) 1211{ 1212 struct l2tp_tunnel *tunnel = session->tunnel; 1213 1214 /* Remove the session from core hashes */ 1215 if (tunnel) { 1216 /* Remove from the per-tunnel hash */ 1217 spin_lock_bh(&tunnel->hlist_lock); 1218 hlist_del_init_rcu(&session->hlist); 1219 spin_unlock_bh(&tunnel->hlist_lock); 1220 1221 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1222 if (tunnel->version != L2TP_HDR_VER_2) { 1223 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1224 1225 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1226 hlist_del_init_rcu(&session->global_hlist); 1227 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1228 } 1229 1230 synchronize_rcu(); 1231 } 1232} 1233 1234/* When the tunnel is closed, all the attached sessions need to go too. 1235 */ 1236static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1237{ 1238 struct l2tp_session *session; 1239 int hash; 1240 1241 spin_lock_bh(&tunnel->hlist_lock); 1242 tunnel->acpt_newsess = false; 1243 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1244again: 1245 hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) { 1246 hlist_del_init_rcu(&session->hlist); 1247 1248 spin_unlock_bh(&tunnel->hlist_lock); 1249 l2tp_session_delete(session); 1250 spin_lock_bh(&tunnel->hlist_lock); 1251 1252 /* Now restart from the beginning of this hash 1253 * chain. We always remove a session from the 1254 * list so we are guaranteed to make forward 1255 * progress. 1256 */ 1257 goto again; 1258 } 1259 } 1260 spin_unlock_bh(&tunnel->hlist_lock); 1261} 1262 1263/* Tunnel socket destroy hook for UDP encapsulation */ 1264static void l2tp_udp_encap_destroy(struct sock *sk) 1265{ 1266 struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk); 1267 1268 if (tunnel) 1269 l2tp_tunnel_delete(tunnel); 1270} 1271 1272static void l2tp_tunnel_remove(struct net *net, struct l2tp_tunnel *tunnel) 1273{ 1274 struct l2tp_net *pn = l2tp_pernet(net); 1275 1276 spin_lock_bh(&pn->l2tp_tunnel_idr_lock); 1277 idr_remove(&pn->l2tp_tunnel_idr, tunnel->tunnel_id); 1278 spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); 1279} 1280 1281/* Workqueue tunnel deletion function */ 1282static void l2tp_tunnel_del_work(struct work_struct *work) 1283{ 1284 struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, 1285 del_work); 1286 struct sock *sk = tunnel->sock; 1287 struct socket *sock = sk->sk_socket; 1288 1289 l2tp_tunnel_closeall(tunnel); 1290 1291 /* If the tunnel socket was created within the kernel, use 1292 * the sk API to release it here. 1293 */ 1294 if (tunnel->fd < 0) { 1295 if (sock) { 1296 kernel_sock_shutdown(sock, SHUT_RDWR); 1297 sock_release(sock); 1298 } 1299 } 1300 1301 l2tp_tunnel_remove(tunnel->l2tp_net, tunnel); 1302 /* drop initial ref */ 1303 l2tp_tunnel_dec_refcount(tunnel); 1304 1305 /* drop workqueue ref */ 1306 l2tp_tunnel_dec_refcount(tunnel); 1307} 1308 1309/* Create a socket for the tunnel, if one isn't set up by 1310 * userspace. This is used for static tunnels where there is no 1311 * managing L2TP daemon. 1312 * 1313 * Since we don't want these sockets to keep a namespace alive by 1314 * themselves, we drop the socket's namespace refcount after creation. 1315 * These sockets are freed when the namespace exits using the pernet 1316 * exit hook. 1317 */ 1318static int l2tp_tunnel_sock_create(struct net *net, 1319 u32 tunnel_id, 1320 u32 peer_tunnel_id, 1321 struct l2tp_tunnel_cfg *cfg, 1322 struct socket **sockp) 1323{ 1324 int err = -EINVAL; 1325 struct socket *sock = NULL; 1326 struct udp_port_cfg udp_conf; 1327 1328 switch (cfg->encap) { 1329 case L2TP_ENCAPTYPE_UDP: 1330 memset(&udp_conf, 0, sizeof(udp_conf)); 1331 1332#if IS_ENABLED(CONFIG_IPV6) 1333 if (cfg->local_ip6 && cfg->peer_ip6) { 1334 udp_conf.family = AF_INET6; 1335 memcpy(&udp_conf.local_ip6, cfg->local_ip6, 1336 sizeof(udp_conf.local_ip6)); 1337 memcpy(&udp_conf.peer_ip6, cfg->peer_ip6, 1338 sizeof(udp_conf.peer_ip6)); 1339 udp_conf.use_udp6_tx_checksums = 1340 !cfg->udp6_zero_tx_checksums; 1341 udp_conf.use_udp6_rx_checksums = 1342 !cfg->udp6_zero_rx_checksums; 1343 } else 1344#endif 1345 { 1346 udp_conf.family = AF_INET; 1347 udp_conf.local_ip = cfg->local_ip; 1348 udp_conf.peer_ip = cfg->peer_ip; 1349 udp_conf.use_udp_checksums = cfg->use_udp_checksums; 1350 } 1351 1352 udp_conf.local_udp_port = htons(cfg->local_udp_port); 1353 udp_conf.peer_udp_port = htons(cfg->peer_udp_port); 1354 1355 err = udp_sock_create(net, &udp_conf, &sock); 1356 if (err < 0) 1357 goto out; 1358 1359 break; 1360 1361 case L2TP_ENCAPTYPE_IP: 1362#if IS_ENABLED(CONFIG_IPV6) 1363 if (cfg->local_ip6 && cfg->peer_ip6) { 1364 struct sockaddr_l2tpip6 ip6_addr = {0}; 1365 1366 err = sock_create_kern(net, AF_INET6, SOCK_DGRAM, 1367 IPPROTO_L2TP, &sock); 1368 if (err < 0) 1369 goto out; 1370 1371 ip6_addr.l2tp_family = AF_INET6; 1372 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6, 1373 sizeof(ip6_addr.l2tp_addr)); 1374 ip6_addr.l2tp_conn_id = tunnel_id; 1375 err = kernel_bind(sock, (struct sockaddr *)&ip6_addr, 1376 sizeof(ip6_addr)); 1377 if (err < 0) 1378 goto out; 1379 1380 ip6_addr.l2tp_family = AF_INET6; 1381 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6, 1382 sizeof(ip6_addr.l2tp_addr)); 1383 ip6_addr.l2tp_conn_id = peer_tunnel_id; 1384 err = kernel_connect(sock, 1385 (struct sockaddr *)&ip6_addr, 1386 sizeof(ip6_addr), 0); 1387 if (err < 0) 1388 goto out; 1389 } else 1390#endif 1391 { 1392 struct sockaddr_l2tpip ip_addr = {0}; 1393 1394 err = sock_create_kern(net, AF_INET, SOCK_DGRAM, 1395 IPPROTO_L2TP, &sock); 1396 if (err < 0) 1397 goto out; 1398 1399 ip_addr.l2tp_family = AF_INET; 1400 ip_addr.l2tp_addr = cfg->local_ip; 1401 ip_addr.l2tp_conn_id = tunnel_id; 1402 err = kernel_bind(sock, (struct sockaddr *)&ip_addr, 1403 sizeof(ip_addr)); 1404 if (err < 0) 1405 goto out; 1406 1407 ip_addr.l2tp_family = AF_INET; 1408 ip_addr.l2tp_addr = cfg->peer_ip; 1409 ip_addr.l2tp_conn_id = peer_tunnel_id; 1410 err = kernel_connect(sock, (struct sockaddr *)&ip_addr, 1411 sizeof(ip_addr), 0); 1412 if (err < 0) 1413 goto out; 1414 } 1415 break; 1416 1417 default: 1418 goto out; 1419 } 1420 1421out: 1422 *sockp = sock; 1423 if (err < 0 && sock) { 1424 kernel_sock_shutdown(sock, SHUT_RDWR); 1425 sock_release(sock); 1426 *sockp = NULL; 1427 } 1428 1429 return err; 1430} 1431 1432int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, 1433 struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp) 1434{ 1435 struct l2tp_tunnel *tunnel = NULL; 1436 int err; 1437 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1438 1439 if (cfg) 1440 encap = cfg->encap; 1441 1442 tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL); 1443 if (!tunnel) { 1444 err = -ENOMEM; 1445 goto err; 1446 } 1447 1448 tunnel->version = version; 1449 tunnel->tunnel_id = tunnel_id; 1450 tunnel->peer_tunnel_id = peer_tunnel_id; 1451 1452 tunnel->magic = L2TP_TUNNEL_MAGIC; 1453 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1454 spin_lock_init(&tunnel->hlist_lock); 1455 tunnel->acpt_newsess = true; 1456 1457 tunnel->encap = encap; 1458 1459 refcount_set(&tunnel->ref_count, 1); 1460 tunnel->fd = fd; 1461 1462 /* Init delete workqueue struct */ 1463 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); 1464 1465 INIT_LIST_HEAD(&tunnel->list); 1466 1467 err = 0; 1468err: 1469 if (tunnelp) 1470 *tunnelp = tunnel; 1471 1472 return err; 1473} 1474EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1475 1476static int l2tp_validate_socket(const struct sock *sk, const struct net *net, 1477 enum l2tp_encap_type encap) 1478{ 1479 if (!net_eq(sock_net(sk), net)) 1480 return -EINVAL; 1481 1482 if (sk->sk_type != SOCK_DGRAM) 1483 return -EPROTONOSUPPORT; 1484 1485 if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6) 1486 return -EPROTONOSUPPORT; 1487 1488 if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) || 1489 (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP)) 1490 return -EPROTONOSUPPORT; 1491 1492 if (sk->sk_user_data) 1493 return -EBUSY; 1494 1495 return 0; 1496} 1497 1498int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 1499 struct l2tp_tunnel_cfg *cfg) 1500{ 1501 struct l2tp_net *pn = l2tp_pernet(net); 1502 u32 tunnel_id = tunnel->tunnel_id; 1503 struct socket *sock; 1504 struct sock *sk; 1505 int ret; 1506 1507 spin_lock_bh(&pn->l2tp_tunnel_idr_lock); 1508 ret = idr_alloc_u32(&pn->l2tp_tunnel_idr, NULL, &tunnel_id, tunnel_id, 1509 GFP_ATOMIC); 1510 spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); 1511 if (ret) 1512 return ret == -ENOSPC ? -EEXIST : ret; 1513 1514 if (tunnel->fd < 0) { 1515 ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id, 1516 tunnel->peer_tunnel_id, cfg, 1517 &sock); 1518 if (ret < 0) 1519 goto err; 1520 } else { 1521 sock = sockfd_lookup(tunnel->fd, &ret); 1522 if (!sock) 1523 goto err; 1524 } 1525 1526 sk = sock->sk; 1527 lock_sock(sk); 1528 write_lock_bh(&sk->sk_callback_lock); 1529 ret = l2tp_validate_socket(sk, net, tunnel->encap); 1530 if (ret < 0) 1531 goto err_inval_sock; 1532 rcu_assign_sk_user_data(sk, tunnel); 1533 write_unlock_bh(&sk->sk_callback_lock); 1534 1535 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1536 struct udp_tunnel_sock_cfg udp_cfg = { 1537 .sk_user_data = tunnel, 1538 .encap_type = UDP_ENCAP_L2TPINUDP, 1539 .encap_rcv = l2tp_udp_encap_recv, 1540 .encap_err_rcv = l2tp_udp_encap_err_recv, 1541 .encap_destroy = l2tp_udp_encap_destroy, 1542 }; 1543 1544 setup_udp_tunnel_sock(net, sock, &udp_cfg); 1545 } 1546 1547 tunnel->old_sk_destruct = sk->sk_destruct; 1548 sk->sk_destruct = &l2tp_tunnel_destruct; 1549 sk->sk_allocation = GFP_ATOMIC; 1550 release_sock(sk); 1551 1552 sock_hold(sk); 1553 tunnel->sock = sk; 1554 tunnel->l2tp_net = net; 1555 1556 spin_lock_bh(&pn->l2tp_tunnel_idr_lock); 1557 idr_replace(&pn->l2tp_tunnel_idr, tunnel, tunnel->tunnel_id); 1558 spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); 1559 1560 trace_register_tunnel(tunnel); 1561 1562 if (tunnel->fd >= 0) 1563 sockfd_put(sock); 1564 1565 return 0; 1566 1567err_inval_sock: 1568 write_unlock_bh(&sk->sk_callback_lock); 1569 release_sock(sk); 1570 1571 if (tunnel->fd < 0) 1572 sock_release(sock); 1573 else 1574 sockfd_put(sock); 1575err: 1576 l2tp_tunnel_remove(net, tunnel); 1577 return ret; 1578} 1579EXPORT_SYMBOL_GPL(l2tp_tunnel_register); 1580 1581/* This function is used by the netlink TUNNEL_DELETE command. 1582 */ 1583void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1584{ 1585 if (!test_and_set_bit(0, &tunnel->dead)) { 1586 trace_delete_tunnel(tunnel); 1587 l2tp_tunnel_inc_refcount(tunnel); 1588 queue_work(l2tp_wq, &tunnel->del_work); 1589 } 1590} 1591EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1592 1593void l2tp_session_delete(struct l2tp_session *session) 1594{ 1595 if (test_and_set_bit(0, &session->dead)) 1596 return; 1597 1598 trace_delete_session(session); 1599 l2tp_session_unhash(session); 1600 l2tp_session_queue_purge(session); 1601 if (session->session_close) 1602 (*session->session_close)(session); 1603 1604 l2tp_session_dec_refcount(session); 1605} 1606EXPORT_SYMBOL_GPL(l2tp_session_delete); 1607 1608/* We come here whenever a session's send_seq, cookie_len or 1609 * l2specific_type parameters are set. 1610 */ 1611void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1612{ 1613 if (version == L2TP_HDR_VER_2) { 1614 session->hdr_len = 6; 1615 if (session->send_seq) 1616 session->hdr_len += 4; 1617 } else { 1618 session->hdr_len = 4 + session->cookie_len; 1619 session->hdr_len += l2tp_get_l2specific_len(session); 1620 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1621 session->hdr_len += 4; 1622 } 1623} 1624EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1625 1626struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, 1627 u32 peer_session_id, struct l2tp_session_cfg *cfg) 1628{ 1629 struct l2tp_session *session; 1630 1631 session = kzalloc(sizeof(*session) + priv_size, GFP_KERNEL); 1632 if (session) { 1633 session->magic = L2TP_SESSION_MAGIC; 1634 session->tunnel = tunnel; 1635 1636 session->session_id = session_id; 1637 session->peer_session_id = peer_session_id; 1638 session->nr = 0; 1639 if (tunnel->version == L2TP_HDR_VER_2) 1640 session->nr_max = 0xffff; 1641 else 1642 session->nr_max = 0xffffff; 1643 session->nr_window_size = session->nr_max / 2; 1644 session->nr_oos_count_max = 4; 1645 1646 /* Use NR of first received packet */ 1647 session->reorder_skip = 1; 1648 1649 sprintf(&session->name[0], "sess %u/%u", 1650 tunnel->tunnel_id, session->session_id); 1651 1652 skb_queue_head_init(&session->reorder_q); 1653 1654 INIT_HLIST_NODE(&session->hlist); 1655 INIT_HLIST_NODE(&session->global_hlist); 1656 1657 if (cfg) { 1658 session->pwtype = cfg->pw_type; 1659 session->send_seq = cfg->send_seq; 1660 session->recv_seq = cfg->recv_seq; 1661 session->lns_mode = cfg->lns_mode; 1662 session->reorder_timeout = cfg->reorder_timeout; 1663 session->l2specific_type = cfg->l2specific_type; 1664 session->cookie_len = cfg->cookie_len; 1665 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1666 session->peer_cookie_len = cfg->peer_cookie_len; 1667 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1668 } 1669 1670 l2tp_session_set_header_len(session, tunnel->version); 1671 1672 refcount_set(&session->ref_count, 1); 1673 1674 return session; 1675 } 1676 1677 return ERR_PTR(-ENOMEM); 1678} 1679EXPORT_SYMBOL_GPL(l2tp_session_create); 1680 1681/***************************************************************************** 1682 * Init and cleanup 1683 *****************************************************************************/ 1684 1685static __net_init int l2tp_init_net(struct net *net) 1686{ 1687 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1688 int hash; 1689 1690 idr_init(&pn->l2tp_tunnel_idr); 1691 spin_lock_init(&pn->l2tp_tunnel_idr_lock); 1692 1693 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1694 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1695 1696 spin_lock_init(&pn->l2tp_session_hlist_lock); 1697 1698 return 0; 1699} 1700 1701static __net_exit void l2tp_exit_net(struct net *net) 1702{ 1703 struct l2tp_net *pn = l2tp_pernet(net); 1704 struct l2tp_tunnel *tunnel = NULL; 1705 unsigned long tunnel_id, tmp; 1706 int hash; 1707 1708 rcu_read_lock_bh(); 1709 idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) { 1710 if (tunnel) 1711 l2tp_tunnel_delete(tunnel); 1712 } 1713 rcu_read_unlock_bh(); 1714 1715 if (l2tp_wq) 1716 flush_workqueue(l2tp_wq); 1717 rcu_barrier(); 1718 1719 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1720 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); 1721 idr_destroy(&pn->l2tp_tunnel_idr); 1722} 1723 1724static struct pernet_operations l2tp_net_ops = { 1725 .init = l2tp_init_net, 1726 .exit = l2tp_exit_net, 1727 .id = &l2tp_net_id, 1728 .size = sizeof(struct l2tp_net), 1729}; 1730 1731static int __init l2tp_init(void) 1732{ 1733 int rc = 0; 1734 1735 rc = register_pernet_device(&l2tp_net_ops); 1736 if (rc) 1737 goto out; 1738 1739 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1740 if (!l2tp_wq) { 1741 pr_err("alloc_workqueue failed\n"); 1742 unregister_pernet_device(&l2tp_net_ops); 1743 rc = -ENOMEM; 1744 goto out; 1745 } 1746 1747 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 1748 1749out: 1750 return rc; 1751} 1752 1753static void __exit l2tp_exit(void) 1754{ 1755 unregister_pernet_device(&l2tp_net_ops); 1756 if (l2tp_wq) { 1757 destroy_workqueue(l2tp_wq); 1758 l2tp_wq = NULL; 1759 } 1760} 1761 1762module_init(l2tp_init); 1763module_exit(l2tp_exit); 1764 1765MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1766MODULE_DESCRIPTION("L2TP core"); 1767MODULE_LICENSE("GPL"); 1768MODULE_VERSION(L2TP_DRV_VERSION); 1769