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 unsigned char *ptr, *optr; 798 u16 hdrflags; 799 u32 tunnel_id, session_id; 800 u16 version; 801 int length; 802 803 /* UDP has verified checksum */ 804 805 /* UDP always verifies the packet length. */ 806 __skb_pull(skb, sizeof(struct udphdr)); 807 808 /* Short packet? */ 809 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX)) { 810 pr_debug_ratelimited("%s: recv short packet (len=%d)\n", 811 tunnel->name, skb->len); 812 goto invalid; 813 } 814 815 /* Point to L2TP header */ 816 optr = skb->data; 817 ptr = skb->data; 818 819 /* Get L2TP header flags */ 820 hdrflags = ntohs(*(__be16 *)ptr); 821 822 /* Check protocol version */ 823 version = hdrflags & L2TP_HDR_VER_MASK; 824 if (version != tunnel->version) { 825 pr_debug_ratelimited("%s: recv protocol version mismatch: got %d expected %d\n", 826 tunnel->name, version, tunnel->version); 827 goto invalid; 828 } 829 830 /* Get length of L2TP packet */ 831 length = skb->len; 832 833 /* If type is control packet, it is handled by userspace. */ 834 if (hdrflags & L2TP_HDRFLAG_T) 835 goto pass; 836 837 /* Skip flags */ 838 ptr += 2; 839 840 if (tunnel->version == L2TP_HDR_VER_2) { 841 /* If length is present, skip it */ 842 if (hdrflags & L2TP_HDRFLAG_L) 843 ptr += 2; 844 845 /* Extract tunnel and session ID */ 846 tunnel_id = ntohs(*(__be16 *)ptr); 847 ptr += 2; 848 session_id = ntohs(*(__be16 *)ptr); 849 ptr += 2; 850 } else { 851 ptr += 2; /* skip reserved bits */ 852 tunnel_id = tunnel->tunnel_id; 853 session_id = ntohl(*(__be32 *)ptr); 854 ptr += 4; 855 } 856 857 /* Find the session context */ 858 session = l2tp_tunnel_get_session(tunnel, session_id); 859 if (!session || !session->recv_skb) { 860 if (session) 861 l2tp_session_dec_refcount(session); 862 863 /* Not found? Pass to userspace to deal with */ 864 pr_debug_ratelimited("%s: no session found (%u/%u). Passing up.\n", 865 tunnel->name, tunnel_id, session_id); 866 goto pass; 867 } 868 869 if (tunnel->version == L2TP_HDR_VER_3 && 870 l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) { 871 l2tp_session_dec_refcount(session); 872 goto invalid; 873 } 874 875 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length); 876 l2tp_session_dec_refcount(session); 877 878 return 0; 879 880 invalid: 881 atomic_long_inc(&tunnel->stats.rx_invalid); 882 883 pass: 884 /* Put UDP header back */ 885 __skb_push(skb, sizeof(struct udphdr)); 886 887 return 1; 888 } 889 890 /* UDP encapsulation receive handler. See net/ipv4/udp.c. 891 * Return codes: 892 * 0 : success. 893 * <0: error 894 * >0: skb should be passed up to userspace as UDP. 895 */ 896 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 897 { 898 struct l2tp_tunnel *tunnel; 899 900 /* Note that this is called from the encap_rcv hook inside an 901 * RCU-protected region, but without the socket being locked. 902 * Hence we use rcu_dereference_sk_user_data to access the 903 * tunnel data structure rather the usual l2tp_sk_to_tunnel 904 * accessor function. 905 */ 906 tunnel = rcu_dereference_sk_user_data(sk); 907 if (!tunnel) 908 goto pass_up; 909 if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC)) 910 goto pass_up; 911 912 if (l2tp_udp_recv_core(tunnel, skb)) 913 goto pass_up; 914 915 return 0; 916 917 pass_up: 918 return 1; 919 } 920 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 921 922 /************************************************************************ 923 * Transmit handling 924 ***********************************************************************/ 925 926 /* Build an L2TP header for the session into the buffer provided. 927 */ 928 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 929 { 930 struct l2tp_tunnel *tunnel = session->tunnel; 931 __be16 *bufp = buf; 932 __be16 *optr = buf; 933 u16 flags = L2TP_HDR_VER_2; 934 u32 tunnel_id = tunnel->peer_tunnel_id; 935 u32 session_id = session->peer_session_id; 936 937 if (session->send_seq) 938 flags |= L2TP_HDRFLAG_S; 939 940 /* Setup L2TP header. */ 941 *bufp++ = htons(flags); 942 *bufp++ = htons(tunnel_id); 943 *bufp++ = htons(session_id); 944 if (session->send_seq) { 945 *bufp++ = htons(session->ns); 946 *bufp++ = 0; 947 session->ns++; 948 session->ns &= 0xffff; 949 trace_session_seqnum_update(session); 950 } 951 952 return bufp - optr; 953 } 954 955 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 956 { 957 struct l2tp_tunnel *tunnel = session->tunnel; 958 char *bufp = buf; 959 char *optr = bufp; 960 961 /* Setup L2TP header. The header differs slightly for UDP and 962 * IP encapsulations. For UDP, there is 4 bytes of flags. 963 */ 964 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 965 u16 flags = L2TP_HDR_VER_3; 966 *((__be16 *)bufp) = htons(flags); 967 bufp += 2; 968 *((__be16 *)bufp) = 0; 969 bufp += 2; 970 } 971 972 *((__be32 *)bufp) = htonl(session->peer_session_id); 973 bufp += 4; 974 if (session->cookie_len) { 975 memcpy(bufp, &session->cookie[0], session->cookie_len); 976 bufp += session->cookie_len; 977 } 978 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 979 u32 l2h = 0; 980 981 if (session->send_seq) { 982 l2h = 0x40000000 | session->ns; 983 session->ns++; 984 session->ns &= 0xffffff; 985 trace_session_seqnum_update(session); 986 } 987 988 *((__be32 *)bufp) = htonl(l2h); 989 bufp += 4; 990 } 991 992 return bufp - optr; 993 } 994 995 /* Queue the packet to IP for output: tunnel socket lock must be held */ 996 static int l2tp_xmit_queue(struct l2tp_tunnel *tunnel, struct sk_buff *skb, struct flowi *fl) 997 { 998 int err; 999 1000 skb->ignore_df = 1; 1001 skb_dst_drop(skb); 1002 #if IS_ENABLED(CONFIG_IPV6) 1003 if (l2tp_sk_is_v6(tunnel->sock)) 1004 err = inet6_csk_xmit(tunnel->sock, skb, NULL); 1005 else 1006 #endif 1007 err = ip_queue_xmit(tunnel->sock, skb, fl); 1008 1009 return err >= 0 ? NET_XMIT_SUCCESS : NET_XMIT_DROP; 1010 } 1011 1012 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, unsigned int *len) 1013 { 1014 struct l2tp_tunnel *tunnel = session->tunnel; 1015 unsigned int data_len = skb->len; 1016 struct sock *sk = tunnel->sock; 1017 int headroom, uhlen, udp_len; 1018 int ret = NET_XMIT_SUCCESS; 1019 struct inet_sock *inet; 1020 struct udphdr *uh; 1021 1022 /* Check that there's enough headroom in the skb to insert IP, 1023 * UDP and L2TP headers. If not enough, expand it to 1024 * make room. Adjust truesize. 1025 */ 1026 uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(*uh) : 0; 1027 headroom = NET_SKB_PAD + sizeof(struct iphdr) + uhlen + session->hdr_len; 1028 if (skb_cow_head(skb, headroom)) { 1029 kfree_skb(skb); 1030 return NET_XMIT_DROP; 1031 } 1032 1033 /* Setup L2TP header */ 1034 if (tunnel->version == L2TP_HDR_VER_2) 1035 l2tp_build_l2tpv2_header(session, __skb_push(skb, session->hdr_len)); 1036 else 1037 l2tp_build_l2tpv3_header(session, __skb_push(skb, session->hdr_len)); 1038 1039 /* Reset skb netfilter state */ 1040 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1041 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | IPSKB_REROUTED); 1042 nf_reset_ct(skb); 1043 1044 bh_lock_sock_nested(sk); 1045 if (sock_owned_by_user(sk)) { 1046 kfree_skb(skb); 1047 ret = NET_XMIT_DROP; 1048 goto out_unlock; 1049 } 1050 1051 /* The user-space may change the connection status for the user-space 1052 * provided socket at run time: we must check it under the socket lock 1053 */ 1054 if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) { 1055 kfree_skb(skb); 1056 ret = NET_XMIT_DROP; 1057 goto out_unlock; 1058 } 1059 1060 /* Report transmitted length before we add encap header, which keeps 1061 * statistics consistent for both UDP and IP encap tx/rx paths. 1062 */ 1063 *len = skb->len; 1064 1065 inet = inet_sk(sk); 1066 switch (tunnel->encap) { 1067 case L2TP_ENCAPTYPE_UDP: 1068 /* Setup UDP header */ 1069 __skb_push(skb, sizeof(*uh)); 1070 skb_reset_transport_header(skb); 1071 uh = udp_hdr(skb); 1072 uh->source = inet->inet_sport; 1073 uh->dest = inet->inet_dport; 1074 udp_len = uhlen + session->hdr_len + data_len; 1075 uh->len = htons(udp_len); 1076 1077 /* Calculate UDP checksum if configured to do so */ 1078 #if IS_ENABLED(CONFIG_IPV6) 1079 if (l2tp_sk_is_v6(sk)) 1080 udp6_set_csum(udp_get_no_check6_tx(sk), 1081 skb, &inet6_sk(sk)->saddr, 1082 &sk->sk_v6_daddr, udp_len); 1083 else 1084 #endif 1085 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr, 1086 inet->inet_daddr, udp_len); 1087 break; 1088 1089 case L2TP_ENCAPTYPE_IP: 1090 break; 1091 } 1092 1093 ret = l2tp_xmit_queue(tunnel, skb, &inet->cork.fl); 1094 1095 out_unlock: 1096 bh_unlock_sock(sk); 1097 1098 return ret; 1099 } 1100 1101 /* If caller requires the skb to have a ppp header, the header must be 1102 * inserted in the skb data before calling this function. 1103 */ 1104 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb) 1105 { 1106 unsigned int len = 0; 1107 int ret; 1108 1109 ret = l2tp_xmit_core(session, skb, &len); 1110 if (ret == NET_XMIT_SUCCESS) { 1111 atomic_long_inc(&session->tunnel->stats.tx_packets); 1112 atomic_long_add(len, &session->tunnel->stats.tx_bytes); 1113 atomic_long_inc(&session->stats.tx_packets); 1114 atomic_long_add(len, &session->stats.tx_bytes); 1115 } else { 1116 atomic_long_inc(&session->tunnel->stats.tx_errors); 1117 atomic_long_inc(&session->stats.tx_errors); 1118 } 1119 return ret; 1120 } 1121 EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1122 1123 /***************************************************************************** 1124 * Tinnel and session create/destroy. 1125 *****************************************************************************/ 1126 1127 /* Tunnel socket destruct hook. 1128 * The tunnel context is deleted only when all session sockets have been 1129 * closed. 1130 */ 1131 static void l2tp_tunnel_destruct(struct sock *sk) 1132 { 1133 struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk); 1134 1135 if (!tunnel) 1136 goto end; 1137 1138 /* Disable udp encapsulation */ 1139 switch (tunnel->encap) { 1140 case L2TP_ENCAPTYPE_UDP: 1141 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1142 (udp_sk(sk))->encap_type = 0; 1143 (udp_sk(sk))->encap_rcv = NULL; 1144 (udp_sk(sk))->encap_destroy = NULL; 1145 break; 1146 case L2TP_ENCAPTYPE_IP: 1147 break; 1148 } 1149 1150 /* Remove hooks into tunnel socket */ 1151 write_lock_bh(&sk->sk_callback_lock); 1152 sk->sk_destruct = tunnel->old_sk_destruct; 1153 sk->sk_user_data = NULL; 1154 write_unlock_bh(&sk->sk_callback_lock); 1155 1156 /* Call the original destructor */ 1157 if (sk->sk_destruct) 1158 (*sk->sk_destruct)(sk); 1159 1160 kfree_rcu(tunnel, rcu); 1161 end: 1162 return; 1163 } 1164 1165 /* Remove an l2tp session from l2tp_core's hash lists. */ 1166 static void l2tp_session_unhash(struct l2tp_session *session) 1167 { 1168 struct l2tp_tunnel *tunnel = session->tunnel; 1169 1170 /* Remove the session from core hashes */ 1171 if (tunnel) { 1172 /* Remove from the per-tunnel hash */ 1173 spin_lock_bh(&tunnel->hlist_lock); 1174 hlist_del_init_rcu(&session->hlist); 1175 spin_unlock_bh(&tunnel->hlist_lock); 1176 1177 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1178 if (tunnel->version != L2TP_HDR_VER_2) { 1179 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1180 1181 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1182 hlist_del_init_rcu(&session->global_hlist); 1183 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1184 } 1185 1186 synchronize_rcu(); 1187 } 1188 } 1189 1190 /* When the tunnel is closed, all the attached sessions need to go too. 1191 */ 1192 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1193 { 1194 struct l2tp_session *session; 1195 int hash; 1196 1197 spin_lock_bh(&tunnel->hlist_lock); 1198 tunnel->acpt_newsess = false; 1199 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1200 again: 1201 hlist_for_each_entry_rcu(session, &tunnel->session_hlist[hash], hlist) { 1202 hlist_del_init_rcu(&session->hlist); 1203 1204 spin_unlock_bh(&tunnel->hlist_lock); 1205 l2tp_session_delete(session); 1206 spin_lock_bh(&tunnel->hlist_lock); 1207 1208 /* Now restart from the beginning of this hash 1209 * chain. We always remove a session from the 1210 * list so we are guaranteed to make forward 1211 * progress. 1212 */ 1213 goto again; 1214 } 1215 } 1216 spin_unlock_bh(&tunnel->hlist_lock); 1217 } 1218 1219 /* Tunnel socket destroy hook for UDP encapsulation */ 1220 static void l2tp_udp_encap_destroy(struct sock *sk) 1221 { 1222 struct l2tp_tunnel *tunnel = l2tp_sk_to_tunnel(sk); 1223 1224 if (tunnel) 1225 l2tp_tunnel_delete(tunnel); 1226 } 1227 1228 static void l2tp_tunnel_remove(struct net *net, struct l2tp_tunnel *tunnel) 1229 { 1230 struct l2tp_net *pn = l2tp_pernet(net); 1231 1232 spin_lock_bh(&pn->l2tp_tunnel_idr_lock); 1233 idr_remove(&pn->l2tp_tunnel_idr, tunnel->tunnel_id); 1234 spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); 1235 } 1236 1237 /* Workqueue tunnel deletion function */ 1238 static void l2tp_tunnel_del_work(struct work_struct *work) 1239 { 1240 struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, 1241 del_work); 1242 struct sock *sk = tunnel->sock; 1243 struct socket *sock = sk->sk_socket; 1244 1245 l2tp_tunnel_closeall(tunnel); 1246 1247 /* If the tunnel socket was created within the kernel, use 1248 * the sk API to release it here. 1249 */ 1250 if (tunnel->fd < 0) { 1251 if (sock) { 1252 kernel_sock_shutdown(sock, SHUT_RDWR); 1253 sock_release(sock); 1254 } 1255 } 1256 1257 l2tp_tunnel_remove(tunnel->l2tp_net, tunnel); 1258 /* drop initial ref */ 1259 l2tp_tunnel_dec_refcount(tunnel); 1260 1261 /* drop workqueue ref */ 1262 l2tp_tunnel_dec_refcount(tunnel); 1263 } 1264 1265 /* Create a socket for the tunnel, if one isn't set up by 1266 * userspace. This is used for static tunnels where there is no 1267 * managing L2TP daemon. 1268 * 1269 * Since we don't want these sockets to keep a namespace alive by 1270 * themselves, we drop the socket's namespace refcount after creation. 1271 * These sockets are freed when the namespace exits using the pernet 1272 * exit hook. 1273 */ 1274 static int l2tp_tunnel_sock_create(struct net *net, 1275 u32 tunnel_id, 1276 u32 peer_tunnel_id, 1277 struct l2tp_tunnel_cfg *cfg, 1278 struct socket **sockp) 1279 { 1280 int err = -EINVAL; 1281 struct socket *sock = NULL; 1282 struct udp_port_cfg udp_conf; 1283 1284 switch (cfg->encap) { 1285 case L2TP_ENCAPTYPE_UDP: 1286 memset(&udp_conf, 0, sizeof(udp_conf)); 1287 1288 #if IS_ENABLED(CONFIG_IPV6) 1289 if (cfg->local_ip6 && cfg->peer_ip6) { 1290 udp_conf.family = AF_INET6; 1291 memcpy(&udp_conf.local_ip6, cfg->local_ip6, 1292 sizeof(udp_conf.local_ip6)); 1293 memcpy(&udp_conf.peer_ip6, cfg->peer_ip6, 1294 sizeof(udp_conf.peer_ip6)); 1295 udp_conf.use_udp6_tx_checksums = 1296 !cfg->udp6_zero_tx_checksums; 1297 udp_conf.use_udp6_rx_checksums = 1298 !cfg->udp6_zero_rx_checksums; 1299 } else 1300 #endif 1301 { 1302 udp_conf.family = AF_INET; 1303 udp_conf.local_ip = cfg->local_ip; 1304 udp_conf.peer_ip = cfg->peer_ip; 1305 udp_conf.use_udp_checksums = cfg->use_udp_checksums; 1306 } 1307 1308 udp_conf.local_udp_port = htons(cfg->local_udp_port); 1309 udp_conf.peer_udp_port = htons(cfg->peer_udp_port); 1310 1311 err = udp_sock_create(net, &udp_conf, &sock); 1312 if (err < 0) 1313 goto out; 1314 1315 break; 1316 1317 case L2TP_ENCAPTYPE_IP: 1318 #if IS_ENABLED(CONFIG_IPV6) 1319 if (cfg->local_ip6 && cfg->peer_ip6) { 1320 struct sockaddr_l2tpip6 ip6_addr = {0}; 1321 1322 err = sock_create_kern(net, AF_INET6, SOCK_DGRAM, 1323 IPPROTO_L2TP, &sock); 1324 if (err < 0) 1325 goto out; 1326 1327 ip6_addr.l2tp_family = AF_INET6; 1328 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6, 1329 sizeof(ip6_addr.l2tp_addr)); 1330 ip6_addr.l2tp_conn_id = tunnel_id; 1331 err = kernel_bind(sock, (struct sockaddr *)&ip6_addr, 1332 sizeof(ip6_addr)); 1333 if (err < 0) 1334 goto out; 1335 1336 ip6_addr.l2tp_family = AF_INET6; 1337 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6, 1338 sizeof(ip6_addr.l2tp_addr)); 1339 ip6_addr.l2tp_conn_id = peer_tunnel_id; 1340 err = kernel_connect(sock, 1341 (struct sockaddr *)&ip6_addr, 1342 sizeof(ip6_addr), 0); 1343 if (err < 0) 1344 goto out; 1345 } else 1346 #endif 1347 { 1348 struct sockaddr_l2tpip ip_addr = {0}; 1349 1350 err = sock_create_kern(net, AF_INET, SOCK_DGRAM, 1351 IPPROTO_L2TP, &sock); 1352 if (err < 0) 1353 goto out; 1354 1355 ip_addr.l2tp_family = AF_INET; 1356 ip_addr.l2tp_addr = cfg->local_ip; 1357 ip_addr.l2tp_conn_id = tunnel_id; 1358 err = kernel_bind(sock, (struct sockaddr *)&ip_addr, 1359 sizeof(ip_addr)); 1360 if (err < 0) 1361 goto out; 1362 1363 ip_addr.l2tp_family = AF_INET; 1364 ip_addr.l2tp_addr = cfg->peer_ip; 1365 ip_addr.l2tp_conn_id = peer_tunnel_id; 1366 err = kernel_connect(sock, (struct sockaddr *)&ip_addr, 1367 sizeof(ip_addr), 0); 1368 if (err < 0) 1369 goto out; 1370 } 1371 break; 1372 1373 default: 1374 goto out; 1375 } 1376 1377 out: 1378 *sockp = sock; 1379 if (err < 0 && sock) { 1380 kernel_sock_shutdown(sock, SHUT_RDWR); 1381 sock_release(sock); 1382 *sockp = NULL; 1383 } 1384 1385 return err; 1386 } 1387 1388 int l2tp_tunnel_create(int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, 1389 struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp) 1390 { 1391 struct l2tp_tunnel *tunnel = NULL; 1392 int err; 1393 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1394 1395 if (cfg) 1396 encap = cfg->encap; 1397 1398 tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL); 1399 if (!tunnel) { 1400 err = -ENOMEM; 1401 goto err; 1402 } 1403 1404 tunnel->version = version; 1405 tunnel->tunnel_id = tunnel_id; 1406 tunnel->peer_tunnel_id = peer_tunnel_id; 1407 1408 tunnel->magic = L2TP_TUNNEL_MAGIC; 1409 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1410 spin_lock_init(&tunnel->hlist_lock); 1411 tunnel->acpt_newsess = true; 1412 1413 tunnel->encap = encap; 1414 1415 refcount_set(&tunnel->ref_count, 1); 1416 tunnel->fd = fd; 1417 1418 /* Init delete workqueue struct */ 1419 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); 1420 1421 INIT_LIST_HEAD(&tunnel->list); 1422 1423 err = 0; 1424 err: 1425 if (tunnelp) 1426 *tunnelp = tunnel; 1427 1428 return err; 1429 } 1430 EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1431 1432 static int l2tp_validate_socket(const struct sock *sk, const struct net *net, 1433 enum l2tp_encap_type encap) 1434 { 1435 if (!net_eq(sock_net(sk), net)) 1436 return -EINVAL; 1437 1438 if (sk->sk_type != SOCK_DGRAM) 1439 return -EPROTONOSUPPORT; 1440 1441 if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6) 1442 return -EPROTONOSUPPORT; 1443 1444 if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) || 1445 (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP)) 1446 return -EPROTONOSUPPORT; 1447 1448 if (sk->sk_user_data) 1449 return -EBUSY; 1450 1451 return 0; 1452 } 1453 1454 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 1455 struct l2tp_tunnel_cfg *cfg) 1456 { 1457 struct l2tp_net *pn = l2tp_pernet(net); 1458 u32 tunnel_id = tunnel->tunnel_id; 1459 struct socket *sock; 1460 struct sock *sk; 1461 int ret; 1462 1463 spin_lock_bh(&pn->l2tp_tunnel_idr_lock); 1464 ret = idr_alloc_u32(&pn->l2tp_tunnel_idr, NULL, &tunnel_id, tunnel_id, 1465 GFP_ATOMIC); 1466 spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); 1467 if (ret) 1468 return ret == -ENOSPC ? -EEXIST : ret; 1469 1470 if (tunnel->fd < 0) { 1471 ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id, 1472 tunnel->peer_tunnel_id, cfg, 1473 &sock); 1474 if (ret < 0) 1475 goto err; 1476 } else { 1477 sock = sockfd_lookup(tunnel->fd, &ret); 1478 if (!sock) 1479 goto err; 1480 } 1481 1482 sk = sock->sk; 1483 lock_sock(sk); 1484 write_lock_bh(&sk->sk_callback_lock); 1485 ret = l2tp_validate_socket(sk, net, tunnel->encap); 1486 if (ret < 0) 1487 goto err_inval_sock; 1488 rcu_assign_sk_user_data(sk, tunnel); 1489 write_unlock_bh(&sk->sk_callback_lock); 1490 1491 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1492 struct udp_tunnel_sock_cfg udp_cfg = { 1493 .sk_user_data = tunnel, 1494 .encap_type = UDP_ENCAP_L2TPINUDP, 1495 .encap_rcv = l2tp_udp_encap_recv, 1496 .encap_destroy = l2tp_udp_encap_destroy, 1497 }; 1498 1499 setup_udp_tunnel_sock(net, sock, &udp_cfg); 1500 } 1501 1502 tunnel->old_sk_destruct = sk->sk_destruct; 1503 sk->sk_destruct = &l2tp_tunnel_destruct; 1504 sk->sk_allocation = GFP_ATOMIC; 1505 release_sock(sk); 1506 1507 sock_hold(sk); 1508 tunnel->sock = sk; 1509 tunnel->l2tp_net = net; 1510 1511 spin_lock_bh(&pn->l2tp_tunnel_idr_lock); 1512 idr_replace(&pn->l2tp_tunnel_idr, tunnel, tunnel->tunnel_id); 1513 spin_unlock_bh(&pn->l2tp_tunnel_idr_lock); 1514 1515 trace_register_tunnel(tunnel); 1516 1517 if (tunnel->fd >= 0) 1518 sockfd_put(sock); 1519 1520 return 0; 1521 1522 err_inval_sock: 1523 write_unlock_bh(&sk->sk_callback_lock); 1524 release_sock(sk); 1525 1526 if (tunnel->fd < 0) 1527 sock_release(sock); 1528 else 1529 sockfd_put(sock); 1530 err: 1531 l2tp_tunnel_remove(net, tunnel); 1532 return ret; 1533 } 1534 EXPORT_SYMBOL_GPL(l2tp_tunnel_register); 1535 1536 /* This function is used by the netlink TUNNEL_DELETE command. 1537 */ 1538 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1539 { 1540 if (!test_and_set_bit(0, &tunnel->dead)) { 1541 trace_delete_tunnel(tunnel); 1542 l2tp_tunnel_inc_refcount(tunnel); 1543 queue_work(l2tp_wq, &tunnel->del_work); 1544 } 1545 } 1546 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1547 1548 void l2tp_session_delete(struct l2tp_session *session) 1549 { 1550 if (test_and_set_bit(0, &session->dead)) 1551 return; 1552 1553 trace_delete_session(session); 1554 l2tp_session_unhash(session); 1555 l2tp_session_queue_purge(session); 1556 if (session->session_close) 1557 (*session->session_close)(session); 1558 1559 l2tp_session_dec_refcount(session); 1560 } 1561 EXPORT_SYMBOL_GPL(l2tp_session_delete); 1562 1563 /* We come here whenever a session's send_seq, cookie_len or 1564 * l2specific_type parameters are set. 1565 */ 1566 void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1567 { 1568 if (version == L2TP_HDR_VER_2) { 1569 session->hdr_len = 6; 1570 if (session->send_seq) 1571 session->hdr_len += 4; 1572 } else { 1573 session->hdr_len = 4 + session->cookie_len; 1574 session->hdr_len += l2tp_get_l2specific_len(session); 1575 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1576 session->hdr_len += 4; 1577 } 1578 } 1579 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1580 1581 struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, 1582 u32 peer_session_id, struct l2tp_session_cfg *cfg) 1583 { 1584 struct l2tp_session *session; 1585 1586 session = kzalloc(sizeof(*session) + priv_size, GFP_KERNEL); 1587 if (session) { 1588 session->magic = L2TP_SESSION_MAGIC; 1589 session->tunnel = tunnel; 1590 1591 session->session_id = session_id; 1592 session->peer_session_id = peer_session_id; 1593 session->nr = 0; 1594 if (tunnel->version == L2TP_HDR_VER_2) 1595 session->nr_max = 0xffff; 1596 else 1597 session->nr_max = 0xffffff; 1598 session->nr_window_size = session->nr_max / 2; 1599 session->nr_oos_count_max = 4; 1600 1601 /* Use NR of first received packet */ 1602 session->reorder_skip = 1; 1603 1604 sprintf(&session->name[0], "sess %u/%u", 1605 tunnel->tunnel_id, session->session_id); 1606 1607 skb_queue_head_init(&session->reorder_q); 1608 1609 INIT_HLIST_NODE(&session->hlist); 1610 INIT_HLIST_NODE(&session->global_hlist); 1611 1612 if (cfg) { 1613 session->pwtype = cfg->pw_type; 1614 session->send_seq = cfg->send_seq; 1615 session->recv_seq = cfg->recv_seq; 1616 session->lns_mode = cfg->lns_mode; 1617 session->reorder_timeout = cfg->reorder_timeout; 1618 session->l2specific_type = cfg->l2specific_type; 1619 session->cookie_len = cfg->cookie_len; 1620 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1621 session->peer_cookie_len = cfg->peer_cookie_len; 1622 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1623 } 1624 1625 l2tp_session_set_header_len(session, tunnel->version); 1626 1627 refcount_set(&session->ref_count, 1); 1628 1629 return session; 1630 } 1631 1632 return ERR_PTR(-ENOMEM); 1633 } 1634 EXPORT_SYMBOL_GPL(l2tp_session_create); 1635 1636 /***************************************************************************** 1637 * Init and cleanup 1638 *****************************************************************************/ 1639 1640 static __net_init int l2tp_init_net(struct net *net) 1641 { 1642 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1643 int hash; 1644 1645 idr_init(&pn->l2tp_tunnel_idr); 1646 spin_lock_init(&pn->l2tp_tunnel_idr_lock); 1647 1648 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1649 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1650 1651 spin_lock_init(&pn->l2tp_session_hlist_lock); 1652 1653 return 0; 1654 } 1655 1656 static __net_exit void l2tp_exit_net(struct net *net) 1657 { 1658 struct l2tp_net *pn = l2tp_pernet(net); 1659 struct l2tp_tunnel *tunnel = NULL; 1660 unsigned long tunnel_id, tmp; 1661 int hash; 1662 1663 rcu_read_lock_bh(); 1664 idr_for_each_entry_ul(&pn->l2tp_tunnel_idr, tunnel, tmp, tunnel_id) { 1665 if (tunnel) 1666 l2tp_tunnel_delete(tunnel); 1667 } 1668 rcu_read_unlock_bh(); 1669 1670 if (l2tp_wq) 1671 flush_workqueue(l2tp_wq); 1672 rcu_barrier(); 1673 1674 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1675 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); 1676 idr_destroy(&pn->l2tp_tunnel_idr); 1677 } 1678 1679 static struct pernet_operations l2tp_net_ops = { 1680 .init = l2tp_init_net, 1681 .exit = l2tp_exit_net, 1682 .id = &l2tp_net_id, 1683 .size = sizeof(struct l2tp_net), 1684 }; 1685 1686 static int __init l2tp_init(void) 1687 { 1688 int rc = 0; 1689 1690 rc = register_pernet_device(&l2tp_net_ops); 1691 if (rc) 1692 goto out; 1693 1694 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1695 if (!l2tp_wq) { 1696 pr_err("alloc_workqueue failed\n"); 1697 unregister_pernet_device(&l2tp_net_ops); 1698 rc = -ENOMEM; 1699 goto out; 1700 } 1701 1702 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 1703 1704 out: 1705 return rc; 1706 } 1707 1708 static void __exit l2tp_exit(void) 1709 { 1710 unregister_pernet_device(&l2tp_net_ops); 1711 if (l2tp_wq) { 1712 destroy_workqueue(l2tp_wq); 1713 l2tp_wq = NULL; 1714 } 1715 } 1716 1717 module_init(l2tp_init); 1718 module_exit(l2tp_exit); 1719 1720 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1721 MODULE_DESCRIPTION("L2TP core"); 1722 MODULE_LICENSE("GPL"); 1723 MODULE_VERSION(L2TP_DRV_VERSION); 1724