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 struct list_head l2tp_tunnel_list; 108 /* Lock for write access to l2tp_tunnel_list */ 109 spinlock_t l2tp_tunnel_list_lock; 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_tunnel *l2tp_tunnel(struct sock *sk) 124 { 125 return sk->sk_user_data; 126 } 127 128 static inline struct l2tp_net *l2tp_pernet(const struct net *net) 129 { 130 return net_generic(net, l2tp_net_id); 131 } 132 133 /* Session hash global list for L2TPv3. 134 * The session_id SHOULD be random according to RFC3931, but several 135 * L2TP implementations use incrementing session_ids. So we do a real 136 * hash on the session_id, rather than a simple bitmask. 137 */ 138 static inline struct hlist_head * 139 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id) 140 { 141 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)]; 142 } 143 144 /* Session hash list. 145 * The session_id SHOULD be random according to RFC2661, but several 146 * L2TP implementations (Cisco and Microsoft) use incrementing 147 * session_ids. So we do a real hash on the session_id, rather than a 148 * simple bitmask. 149 */ 150 static inline struct hlist_head * 151 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id) 152 { 153 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)]; 154 } 155 156 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) 157 { 158 trace_free_tunnel(tunnel); 159 sock_put(tunnel->sock); 160 /* the tunnel is freed in the socket destructor */ 161 } 162 163 static void l2tp_session_free(struct l2tp_session *session) 164 { 165 struct l2tp_tunnel *tunnel = session->tunnel; 166 167 trace_free_session(session); 168 169 if (tunnel) { 170 if (WARN_ON(tunnel->magic != L2TP_TUNNEL_MAGIC)) 171 goto out; 172 l2tp_tunnel_dec_refcount(tunnel); 173 } 174 175 out: 176 kfree(session); 177 } 178 179 void l2tp_tunnel_inc_refcount(struct l2tp_tunnel *tunnel) 180 { 181 refcount_inc(&tunnel->ref_count); 182 } 183 EXPORT_SYMBOL_GPL(l2tp_tunnel_inc_refcount); 184 185 void l2tp_tunnel_dec_refcount(struct l2tp_tunnel *tunnel) 186 { 187 if (refcount_dec_and_test(&tunnel->ref_count)) 188 l2tp_tunnel_free(tunnel); 189 } 190 EXPORT_SYMBOL_GPL(l2tp_tunnel_dec_refcount); 191 192 void l2tp_session_inc_refcount(struct l2tp_session *session) 193 { 194 refcount_inc(&session->ref_count); 195 } 196 EXPORT_SYMBOL_GPL(l2tp_session_inc_refcount); 197 198 void l2tp_session_dec_refcount(struct l2tp_session *session) 199 { 200 if (refcount_dec_and_test(&session->ref_count)) 201 l2tp_session_free(session); 202 } 203 EXPORT_SYMBOL_GPL(l2tp_session_dec_refcount); 204 205 /* Lookup a tunnel. A new reference is held on the returned tunnel. */ 206 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id) 207 { 208 const struct l2tp_net *pn = l2tp_pernet(net); 209 struct l2tp_tunnel *tunnel; 210 211 rcu_read_lock_bh(); 212 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 213 if (tunnel->tunnel_id == tunnel_id && 214 refcount_inc_not_zero(&tunnel->ref_count)) { 215 rcu_read_unlock_bh(); 216 217 return tunnel; 218 } 219 } 220 rcu_read_unlock_bh(); 221 222 return NULL; 223 } 224 EXPORT_SYMBOL_GPL(l2tp_tunnel_get); 225 226 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth) 227 { 228 const struct l2tp_net *pn = l2tp_pernet(net); 229 struct l2tp_tunnel *tunnel; 230 int count = 0; 231 232 rcu_read_lock_bh(); 233 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 234 if (++count > nth && 235 refcount_inc_not_zero(&tunnel->ref_count)) { 236 rcu_read_unlock_bh(); 237 return tunnel; 238 } 239 } 240 rcu_read_unlock_bh(); 241 242 return NULL; 243 } 244 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth); 245 246 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel, 247 u32 session_id) 248 { 249 struct hlist_head *session_list; 250 struct l2tp_session *session; 251 252 session_list = l2tp_session_id_hash(tunnel, session_id); 253 254 read_lock_bh(&tunnel->hlist_lock); 255 hlist_for_each_entry(session, session_list, hlist) 256 if (session->session_id == session_id) { 257 l2tp_session_inc_refcount(session); 258 read_unlock_bh(&tunnel->hlist_lock); 259 260 return session; 261 } 262 read_unlock_bh(&tunnel->hlist_lock); 263 264 return NULL; 265 } 266 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_session); 267 268 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id) 269 { 270 struct hlist_head *session_list; 271 struct l2tp_session *session; 272 273 session_list = l2tp_session_id_hash_2(l2tp_pernet(net), session_id); 274 275 rcu_read_lock_bh(); 276 hlist_for_each_entry_rcu(session, session_list, global_hlist) 277 if (session->session_id == session_id) { 278 l2tp_session_inc_refcount(session); 279 rcu_read_unlock_bh(); 280 281 return session; 282 } 283 rcu_read_unlock_bh(); 284 285 return NULL; 286 } 287 EXPORT_SYMBOL_GPL(l2tp_session_get); 288 289 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth) 290 { 291 int hash; 292 struct l2tp_session *session; 293 int count = 0; 294 295 read_lock_bh(&tunnel->hlist_lock); 296 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 297 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) { 298 if (++count > nth) { 299 l2tp_session_inc_refcount(session); 300 read_unlock_bh(&tunnel->hlist_lock); 301 return session; 302 } 303 } 304 } 305 306 read_unlock_bh(&tunnel->hlist_lock); 307 308 return NULL; 309 } 310 EXPORT_SYMBOL_GPL(l2tp_session_get_nth); 311 312 /* Lookup a session by interface name. 313 * This is very inefficient but is only used by management interfaces. 314 */ 315 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net, 316 const char *ifname) 317 { 318 struct l2tp_net *pn = l2tp_pernet(net); 319 int hash; 320 struct l2tp_session *session; 321 322 rcu_read_lock_bh(); 323 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { 324 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) { 325 if (!strcmp(session->ifname, ifname)) { 326 l2tp_session_inc_refcount(session); 327 rcu_read_unlock_bh(); 328 329 return session; 330 } 331 } 332 } 333 334 rcu_read_unlock_bh(); 335 336 return NULL; 337 } 338 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname); 339 340 int l2tp_session_register(struct l2tp_session *session, 341 struct l2tp_tunnel *tunnel) 342 { 343 struct l2tp_session *session_walk; 344 struct hlist_head *g_head; 345 struct hlist_head *head; 346 struct l2tp_net *pn; 347 int err; 348 349 head = l2tp_session_id_hash(tunnel, session->session_id); 350 351 write_lock_bh(&tunnel->hlist_lock); 352 if (!tunnel->acpt_newsess) { 353 err = -ENODEV; 354 goto err_tlock; 355 } 356 357 hlist_for_each_entry(session_walk, head, hlist) 358 if (session_walk->session_id == session->session_id) { 359 err = -EEXIST; 360 goto err_tlock; 361 } 362 363 if (tunnel->version == L2TP_HDR_VER_3) { 364 pn = l2tp_pernet(tunnel->l2tp_net); 365 g_head = l2tp_session_id_hash_2(pn, session->session_id); 366 367 spin_lock_bh(&pn->l2tp_session_hlist_lock); 368 369 /* IP encap expects session IDs to be globally unique, while 370 * UDP encap doesn't. 371 */ 372 hlist_for_each_entry(session_walk, g_head, global_hlist) 373 if (session_walk->session_id == session->session_id && 374 (session_walk->tunnel->encap == L2TP_ENCAPTYPE_IP || 375 tunnel->encap == L2TP_ENCAPTYPE_IP)) { 376 err = -EEXIST; 377 goto err_tlock_pnlock; 378 } 379 380 l2tp_tunnel_inc_refcount(tunnel); 381 hlist_add_head_rcu(&session->global_hlist, g_head); 382 383 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 384 } else { 385 l2tp_tunnel_inc_refcount(tunnel); 386 } 387 388 hlist_add_head(&session->hlist, head); 389 write_unlock_bh(&tunnel->hlist_lock); 390 391 trace_register_session(session); 392 393 return 0; 394 395 err_tlock_pnlock: 396 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 397 err_tlock: 398 write_unlock_bh(&tunnel->hlist_lock); 399 400 return err; 401 } 402 EXPORT_SYMBOL_GPL(l2tp_session_register); 403 404 /***************************************************************************** 405 * Receive data handling 406 *****************************************************************************/ 407 408 /* Queue a skb in order. We come here only if the skb has an L2TP sequence 409 * number. 410 */ 411 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb) 412 { 413 struct sk_buff *skbp; 414 struct sk_buff *tmp; 415 u32 ns = L2TP_SKB_CB(skb)->ns; 416 417 spin_lock_bh(&session->reorder_q.lock); 418 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) { 419 if (L2TP_SKB_CB(skbp)->ns > ns) { 420 __skb_queue_before(&session->reorder_q, skbp, skb); 421 atomic_long_inc(&session->stats.rx_oos_packets); 422 goto out; 423 } 424 } 425 426 __skb_queue_tail(&session->reorder_q, skb); 427 428 out: 429 spin_unlock_bh(&session->reorder_q.lock); 430 } 431 432 /* Dequeue a single skb. 433 */ 434 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb) 435 { 436 struct l2tp_tunnel *tunnel = session->tunnel; 437 int length = L2TP_SKB_CB(skb)->length; 438 439 /* We're about to requeue the skb, so return resources 440 * to its current owner (a socket receive buffer). 441 */ 442 skb_orphan(skb); 443 444 atomic_long_inc(&tunnel->stats.rx_packets); 445 atomic_long_add(length, &tunnel->stats.rx_bytes); 446 atomic_long_inc(&session->stats.rx_packets); 447 atomic_long_add(length, &session->stats.rx_bytes); 448 449 if (L2TP_SKB_CB(skb)->has_seq) { 450 /* Bump our Nr */ 451 session->nr++; 452 session->nr &= session->nr_max; 453 trace_session_seqnum_update(session); 454 } 455 456 /* call private receive handler */ 457 if (session->recv_skb) 458 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); 459 else 460 kfree_skb(skb); 461 } 462 463 /* Dequeue skbs from the session's reorder_q, subject to packet order. 464 * Skbs that have been in the queue for too long are simply discarded. 465 */ 466 static void l2tp_recv_dequeue(struct l2tp_session *session) 467 { 468 struct sk_buff *skb; 469 struct sk_buff *tmp; 470 471 /* If the pkt at the head of the queue has the nr that we 472 * expect to send up next, dequeue it and any other 473 * in-sequence packets behind it. 474 */ 475 start: 476 spin_lock_bh(&session->reorder_q.lock); 477 skb_queue_walk_safe(&session->reorder_q, skb, tmp) { 478 struct l2tp_skb_cb *cb = L2TP_SKB_CB(skb); 479 480 /* If the packet has been pending on the queue for too long, discard it */ 481 if (time_after(jiffies, cb->expires)) { 482 atomic_long_inc(&session->stats.rx_seq_discards); 483 atomic_long_inc(&session->stats.rx_errors); 484 trace_session_pkt_expired(session, cb->ns); 485 session->reorder_skip = 1; 486 __skb_unlink(skb, &session->reorder_q); 487 kfree_skb(skb); 488 continue; 489 } 490 491 if (cb->has_seq) { 492 if (session->reorder_skip) { 493 session->reorder_skip = 0; 494 session->nr = cb->ns; 495 trace_session_seqnum_reset(session); 496 } 497 if (cb->ns != session->nr) 498 goto out; 499 } 500 __skb_unlink(skb, &session->reorder_q); 501 502 /* Process the skb. We release the queue lock while we 503 * do so to let other contexts process the queue. 504 */ 505 spin_unlock_bh(&session->reorder_q.lock); 506 l2tp_recv_dequeue_skb(session, skb); 507 goto start; 508 } 509 510 out: 511 spin_unlock_bh(&session->reorder_q.lock); 512 } 513 514 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr) 515 { 516 u32 nws; 517 518 if (nr >= session->nr) 519 nws = nr - session->nr; 520 else 521 nws = (session->nr_max + 1) - (session->nr - nr); 522 523 return nws < session->nr_window_size; 524 } 525 526 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if 527 * acceptable, else non-zero. 528 */ 529 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb) 530 { 531 struct l2tp_skb_cb *cb = L2TP_SKB_CB(skb); 532 533 if (!l2tp_seq_check_rx_window(session, cb->ns)) { 534 /* Packet sequence number is outside allowed window. 535 * Discard it. 536 */ 537 trace_session_pkt_outside_rx_window(session, cb->ns); 538 goto discard; 539 } 540 541 if (session->reorder_timeout != 0) { 542 /* Packet reordering enabled. Add skb to session's 543 * reorder queue, in order of ns. 544 */ 545 l2tp_recv_queue_skb(session, skb); 546 goto out; 547 } 548 549 /* Packet reordering disabled. Discard out-of-sequence packets, while 550 * tracking the number if in-sequence packets after the first OOS packet 551 * is seen. After nr_oos_count_max in-sequence packets, reset the 552 * sequence number to re-enable packet reception. 553 */ 554 if (cb->ns == session->nr) { 555 skb_queue_tail(&session->reorder_q, skb); 556 } else { 557 u32 nr_oos = cb->ns; 558 u32 nr_next = (session->nr_oos + 1) & session->nr_max; 559 560 if (nr_oos == nr_next) 561 session->nr_oos_count++; 562 else 563 session->nr_oos_count = 0; 564 565 session->nr_oos = nr_oos; 566 if (session->nr_oos_count > session->nr_oos_count_max) { 567 session->reorder_skip = 1; 568 } 569 if (!session->reorder_skip) { 570 atomic_long_inc(&session->stats.rx_seq_discards); 571 trace_session_pkt_oos(session, cb->ns); 572 goto discard; 573 } 574 skb_queue_tail(&session->reorder_q, skb); 575 } 576 577 out: 578 return 0; 579 580 discard: 581 return 1; 582 } 583 584 /* Do receive processing of L2TP data frames. We handle both L2TPv2 585 * and L2TPv3 data frames here. 586 * 587 * L2TPv2 Data Message Header 588 * 589 * 0 1 2 3 590 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 591 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 592 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) | 593 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 594 * | Tunnel ID | Session ID | 595 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 596 * | Ns (opt) | Nr (opt) | 597 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 598 * | Offset Size (opt) | Offset pad... (opt) 599 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 600 * 601 * Data frames are marked by T=0. All other fields are the same as 602 * those in L2TP control frames. 603 * 604 * L2TPv3 Data Message Header 605 * 606 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 607 * | L2TP Session Header | 608 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 609 * | L2-Specific Sublayer | 610 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 611 * | Tunnel Payload ... 612 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 613 * 614 * L2TPv3 Session Header Over IP 615 * 616 * 0 1 2 3 617 * 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 1 618 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 619 * | Session ID | 620 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 621 * | Cookie (optional, maximum 64 bits)... 622 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 623 * | 624 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 625 * 626 * L2TPv3 L2-Specific Sublayer Format 627 * 628 * 0 1 2 3 629 * 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 1 630 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 631 * |x|S|x|x|x|x|x|x| Sequence Number | 632 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 633 * 634 * Cookie value and sublayer format are negotiated with the peer when 635 * the session is set up. Unlike L2TPv2, we do not need to parse the 636 * packet header to determine if optional fields are present. 637 * 638 * Caller must already have parsed the frame and determined that it is 639 * a data (not control) frame before coming here. Fields up to the 640 * session-id have already been parsed and ptr points to the data 641 * after the session-id. 642 */ 643 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 644 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 645 int length) 646 { 647 struct l2tp_tunnel *tunnel = session->tunnel; 648 int offset; 649 650 /* Parse and check optional cookie */ 651 if (session->peer_cookie_len > 0) { 652 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { 653 pr_warn_ratelimited("%s: cookie mismatch (%u/%u). Discarding.\n", 654 tunnel->name, tunnel->tunnel_id, 655 session->session_id); 656 atomic_long_inc(&session->stats.rx_cookie_discards); 657 goto discard; 658 } 659 ptr += session->peer_cookie_len; 660 } 661 662 /* Handle the optional sequence numbers. Sequence numbers are 663 * in different places for L2TPv2 and L2TPv3. 664 * 665 * If we are the LAC, enable/disable sequence numbers under 666 * the control of the LNS. If no sequence numbers present but 667 * we were expecting them, discard frame. 668 */ 669 L2TP_SKB_CB(skb)->has_seq = 0; 670 if (tunnel->version == L2TP_HDR_VER_2) { 671 if (hdrflags & L2TP_HDRFLAG_S) { 672 /* Store L2TP info in the skb */ 673 L2TP_SKB_CB(skb)->ns = ntohs(*(__be16 *)ptr); 674 L2TP_SKB_CB(skb)->has_seq = 1; 675 ptr += 2; 676 /* Skip past nr in the header */ 677 ptr += 2; 678 679 } 680 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 681 u32 l2h = ntohl(*(__be32 *)ptr); 682 683 if (l2h & 0x40000000) { 684 /* Store L2TP info in the skb */ 685 L2TP_SKB_CB(skb)->ns = l2h & 0x00ffffff; 686 L2TP_SKB_CB(skb)->has_seq = 1; 687 } 688 ptr += 4; 689 } 690 691 if (L2TP_SKB_CB(skb)->has_seq) { 692 /* Received a packet with sequence numbers. If we're the LAC, 693 * check if we sre sending sequence numbers and if not, 694 * configure it so. 695 */ 696 if (!session->lns_mode && !session->send_seq) { 697 trace_session_seqnum_lns_enable(session); 698 session->send_seq = 1; 699 l2tp_session_set_header_len(session, tunnel->version); 700 } 701 } else { 702 /* No sequence numbers. 703 * If user has configured mandatory sequence numbers, discard. 704 */ 705 if (session->recv_seq) { 706 pr_warn_ratelimited("%s: recv data has no seq numbers when required. Discarding.\n", 707 session->name); 708 atomic_long_inc(&session->stats.rx_seq_discards); 709 goto discard; 710 } 711 712 /* If we're the LAC and we're sending sequence numbers, the 713 * LNS has requested that we no longer send sequence numbers. 714 * If we're the LNS and we're sending sequence numbers, the 715 * LAC is broken. Discard the frame. 716 */ 717 if (!session->lns_mode && session->send_seq) { 718 trace_session_seqnum_lns_disable(session); 719 session->send_seq = 0; 720 l2tp_session_set_header_len(session, tunnel->version); 721 } else if (session->send_seq) { 722 pr_warn_ratelimited("%s: recv data has no seq numbers when required. Discarding.\n", 723 session->name); 724 atomic_long_inc(&session->stats.rx_seq_discards); 725 goto discard; 726 } 727 } 728 729 /* Session data offset is defined only for L2TPv2 and is 730 * indicated by an optional 16-bit value in the header. 731 */ 732 if (tunnel->version == L2TP_HDR_VER_2) { 733 /* If offset bit set, skip it. */ 734 if (hdrflags & L2TP_HDRFLAG_O) { 735 offset = ntohs(*(__be16 *)ptr); 736 ptr += 2 + offset; 737 } 738 } 739 740 offset = ptr - optr; 741 if (!pskb_may_pull(skb, offset)) 742 goto discard; 743 744 __skb_pull(skb, offset); 745 746 /* Prepare skb for adding to the session's reorder_q. Hold 747 * packets for max reorder_timeout or 1 second if not 748 * reordering. 749 */ 750 L2TP_SKB_CB(skb)->length = length; 751 L2TP_SKB_CB(skb)->expires = jiffies + 752 (session->reorder_timeout ? session->reorder_timeout : HZ); 753 754 /* Add packet to the session's receive queue. Reordering is done here, if 755 * enabled. Saved L2TP protocol info is stored in skb->sb[]. 756 */ 757 if (L2TP_SKB_CB(skb)->has_seq) { 758 if (l2tp_recv_data_seq(session, skb)) 759 goto discard; 760 } else { 761 /* No sequence numbers. Add the skb to the tail of the 762 * reorder queue. This ensures that it will be 763 * delivered after all previous sequenced skbs. 764 */ 765 skb_queue_tail(&session->reorder_q, skb); 766 } 767 768 /* Try to dequeue as many skbs from reorder_q as we can. */ 769 l2tp_recv_dequeue(session); 770 771 return; 772 773 discard: 774 atomic_long_inc(&session->stats.rx_errors); 775 kfree_skb(skb); 776 } 777 EXPORT_SYMBOL_GPL(l2tp_recv_common); 778 779 /* Drop skbs from the session's reorder_q 780 */ 781 static void l2tp_session_queue_purge(struct l2tp_session *session) 782 { 783 struct sk_buff *skb = NULL; 784 785 if (WARN_ON(session->magic != L2TP_SESSION_MAGIC)) 786 return; 787 788 while ((skb = skb_dequeue(&session->reorder_q))) { 789 atomic_long_inc(&session->stats.rx_errors); 790 kfree_skb(skb); 791 } 792 } 793 794 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame 795 * here. The skb is not on a list when we get here. 796 * Returns 0 if the packet was a data packet and was successfully passed on. 797 * Returns 1 if the packet was not a good data packet and could not be 798 * forwarded. All such packets are passed up to userspace to deal with. 799 */ 800 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb) 801 { 802 struct l2tp_session *session = NULL; 803 unsigned char *ptr, *optr; 804 u16 hdrflags; 805 u32 tunnel_id, session_id; 806 u16 version; 807 int length; 808 809 /* UDP has verifed checksum */ 810 811 /* UDP always verifies the packet length. */ 812 __skb_pull(skb, sizeof(struct udphdr)); 813 814 /* Short packet? */ 815 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX)) { 816 pr_warn_ratelimited("%s: recv short packet (len=%d)\n", 817 tunnel->name, skb->len); 818 goto error; 819 } 820 821 /* Point to L2TP header */ 822 optr = skb->data; 823 ptr = skb->data; 824 825 /* Get L2TP header flags */ 826 hdrflags = ntohs(*(__be16 *)ptr); 827 828 /* Check protocol version */ 829 version = hdrflags & L2TP_HDR_VER_MASK; 830 if (version != tunnel->version) { 831 pr_warn_ratelimited("%s: recv protocol version mismatch: got %d expected %d\n", 832 tunnel->name, version, tunnel->version); 833 goto error; 834 } 835 836 /* Get length of L2TP packet */ 837 length = skb->len; 838 839 /* If type is control packet, it is handled by userspace. */ 840 if (hdrflags & L2TP_HDRFLAG_T) 841 goto error; 842 843 /* Skip flags */ 844 ptr += 2; 845 846 if (tunnel->version == L2TP_HDR_VER_2) { 847 /* If length is present, skip it */ 848 if (hdrflags & L2TP_HDRFLAG_L) 849 ptr += 2; 850 851 /* Extract tunnel and session ID */ 852 tunnel_id = ntohs(*(__be16 *)ptr); 853 ptr += 2; 854 session_id = ntohs(*(__be16 *)ptr); 855 ptr += 2; 856 } else { 857 ptr += 2; /* skip reserved bits */ 858 tunnel_id = tunnel->tunnel_id; 859 session_id = ntohl(*(__be32 *)ptr); 860 ptr += 4; 861 } 862 863 /* Find the session context */ 864 session = l2tp_tunnel_get_session(tunnel, session_id); 865 if (!session || !session->recv_skb) { 866 if (session) 867 l2tp_session_dec_refcount(session); 868 869 /* Not found? Pass to userspace to deal with */ 870 pr_warn_ratelimited("%s: no session found (%u/%u). Passing up.\n", 871 tunnel->name, tunnel_id, session_id); 872 goto error; 873 } 874 875 if (tunnel->version == L2TP_HDR_VER_3 && 876 l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr)) 877 goto error; 878 879 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length); 880 l2tp_session_dec_refcount(session); 881 882 return 0; 883 884 error: 885 /* Put UDP header back */ 886 __skb_push(skb, sizeof(struct udphdr)); 887 888 return 1; 889 } 890 891 /* UDP encapsulation receive handler. See net/ipv4/udp.c. 892 * Return codes: 893 * 0 : success. 894 * <0: error 895 * >0: skb should be passed up to userspace as UDP. 896 */ 897 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 898 { 899 struct l2tp_tunnel *tunnel; 900 901 tunnel = rcu_dereference_sk_user_data(sk); 902 if (!tunnel) 903 goto pass_up; 904 905 if (l2tp_udp_recv_core(tunnel, skb)) 906 goto pass_up; 907 908 return 0; 909 910 pass_up: 911 return 1; 912 } 913 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 914 915 /************************************************************************ 916 * Transmit handling 917 ***********************************************************************/ 918 919 /* Build an L2TP header for the session into the buffer provided. 920 */ 921 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 922 { 923 struct l2tp_tunnel *tunnel = session->tunnel; 924 __be16 *bufp = buf; 925 __be16 *optr = buf; 926 u16 flags = L2TP_HDR_VER_2; 927 u32 tunnel_id = tunnel->peer_tunnel_id; 928 u32 session_id = session->peer_session_id; 929 930 if (session->send_seq) 931 flags |= L2TP_HDRFLAG_S; 932 933 /* Setup L2TP header. */ 934 *bufp++ = htons(flags); 935 *bufp++ = htons(tunnel_id); 936 *bufp++ = htons(session_id); 937 if (session->send_seq) { 938 *bufp++ = htons(session->ns); 939 *bufp++ = 0; 940 session->ns++; 941 session->ns &= 0xffff; 942 trace_session_seqnum_update(session); 943 } 944 945 return bufp - optr; 946 } 947 948 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 949 { 950 struct l2tp_tunnel *tunnel = session->tunnel; 951 char *bufp = buf; 952 char *optr = bufp; 953 954 /* Setup L2TP header. The header differs slightly for UDP and 955 * IP encapsulations. For UDP, there is 4 bytes of flags. 956 */ 957 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 958 u16 flags = L2TP_HDR_VER_3; 959 *((__be16 *)bufp) = htons(flags); 960 bufp += 2; 961 *((__be16 *)bufp) = 0; 962 bufp += 2; 963 } 964 965 *((__be32 *)bufp) = htonl(session->peer_session_id); 966 bufp += 4; 967 if (session->cookie_len) { 968 memcpy(bufp, &session->cookie[0], session->cookie_len); 969 bufp += session->cookie_len; 970 } 971 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 972 u32 l2h = 0; 973 974 if (session->send_seq) { 975 l2h = 0x40000000 | session->ns; 976 session->ns++; 977 session->ns &= 0xffffff; 978 trace_session_seqnum_update(session); 979 } 980 981 *((__be32 *)bufp) = htonl(l2h); 982 bufp += 4; 983 } 984 985 return bufp - optr; 986 } 987 988 static void l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, 989 struct flowi *fl, size_t data_len) 990 { 991 struct l2tp_tunnel *tunnel = session->tunnel; 992 unsigned int len = skb->len; 993 int error; 994 995 /* Queue the packet to IP for output */ 996 skb->ignore_df = 1; 997 skb_dst_drop(skb); 998 #if IS_ENABLED(CONFIG_IPV6) 999 if (l2tp_sk_is_v6(tunnel->sock)) 1000 error = inet6_csk_xmit(tunnel->sock, skb, NULL); 1001 else 1002 #endif 1003 error = ip_queue_xmit(tunnel->sock, skb, fl); 1004 1005 /* Update stats */ 1006 if (error >= 0) { 1007 atomic_long_inc(&tunnel->stats.tx_packets); 1008 atomic_long_add(len, &tunnel->stats.tx_bytes); 1009 atomic_long_inc(&session->stats.tx_packets); 1010 atomic_long_add(len, &session->stats.tx_bytes); 1011 } else { 1012 atomic_long_inc(&tunnel->stats.tx_errors); 1013 atomic_long_inc(&session->stats.tx_errors); 1014 } 1015 } 1016 1017 /* If caller requires the skb to have a ppp header, the header must be 1018 * inserted in the skb data before calling this function. 1019 */ 1020 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len) 1021 { 1022 int data_len = skb->len; 1023 struct l2tp_tunnel *tunnel = session->tunnel; 1024 struct sock *sk = tunnel->sock; 1025 struct flowi *fl; 1026 struct udphdr *uh; 1027 struct inet_sock *inet; 1028 int headroom; 1029 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1030 int udp_len; 1031 int ret = NET_XMIT_SUCCESS; 1032 1033 /* Check that there's enough headroom in the skb to insert IP, 1034 * UDP and L2TP headers. If not enough, expand it to 1035 * make room. Adjust truesize. 1036 */ 1037 headroom = NET_SKB_PAD + sizeof(struct iphdr) + 1038 uhlen + hdr_len; 1039 if (skb_cow_head(skb, headroom)) { 1040 kfree_skb(skb); 1041 return NET_XMIT_DROP; 1042 } 1043 1044 /* Setup L2TP header */ 1045 if (tunnel->version == L2TP_HDR_VER_2) 1046 l2tp_build_l2tpv2_header(session, __skb_push(skb, hdr_len)); 1047 else 1048 l2tp_build_l2tpv3_header(session, __skb_push(skb, hdr_len)); 1049 1050 /* Reset skb netfilter state */ 1051 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1052 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | 1053 IPSKB_REROUTED); 1054 nf_reset_ct(skb); 1055 1056 bh_lock_sock(sk); 1057 if (sock_owned_by_user(sk)) { 1058 kfree_skb(skb); 1059 ret = NET_XMIT_DROP; 1060 goto out_unlock; 1061 } 1062 1063 /* The user-space may change the connection status for the user-space 1064 * provided socket at run time: we must check it under the socket lock 1065 */ 1066 if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) { 1067 kfree_skb(skb); 1068 ret = NET_XMIT_DROP; 1069 goto out_unlock; 1070 } 1071 1072 inet = inet_sk(sk); 1073 fl = &inet->cork.fl; 1074 switch (tunnel->encap) { 1075 case L2TP_ENCAPTYPE_UDP: 1076 /* Setup UDP header */ 1077 __skb_push(skb, sizeof(*uh)); 1078 skb_reset_transport_header(skb); 1079 uh = udp_hdr(skb); 1080 uh->source = inet->inet_sport; 1081 uh->dest = inet->inet_dport; 1082 udp_len = uhlen + hdr_len + data_len; 1083 uh->len = htons(udp_len); 1084 1085 /* Calculate UDP checksum if configured to do so */ 1086 #if IS_ENABLED(CONFIG_IPV6) 1087 if (l2tp_sk_is_v6(sk)) 1088 udp6_set_csum(udp_get_no_check6_tx(sk), 1089 skb, &inet6_sk(sk)->saddr, 1090 &sk->sk_v6_daddr, udp_len); 1091 else 1092 #endif 1093 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr, 1094 inet->inet_daddr, udp_len); 1095 break; 1096 1097 case L2TP_ENCAPTYPE_IP: 1098 break; 1099 } 1100 1101 l2tp_xmit_core(session, skb, fl, data_len); 1102 out_unlock: 1103 bh_unlock_sock(sk); 1104 1105 return ret; 1106 } 1107 EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1108 1109 /***************************************************************************** 1110 * Tinnel and session create/destroy. 1111 *****************************************************************************/ 1112 1113 /* Tunnel socket destruct hook. 1114 * The tunnel context is deleted only when all session sockets have been 1115 * closed. 1116 */ 1117 static void l2tp_tunnel_destruct(struct sock *sk) 1118 { 1119 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1120 1121 if (!tunnel) 1122 goto end; 1123 1124 /* Disable udp encapsulation */ 1125 switch (tunnel->encap) { 1126 case L2TP_ENCAPTYPE_UDP: 1127 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1128 (udp_sk(sk))->encap_type = 0; 1129 (udp_sk(sk))->encap_rcv = NULL; 1130 (udp_sk(sk))->encap_destroy = NULL; 1131 break; 1132 case L2TP_ENCAPTYPE_IP: 1133 break; 1134 } 1135 1136 /* Remove hooks into tunnel socket */ 1137 sk->sk_destruct = tunnel->old_sk_destruct; 1138 sk->sk_user_data = NULL; 1139 1140 /* Call the original destructor */ 1141 if (sk->sk_destruct) 1142 (*sk->sk_destruct)(sk); 1143 1144 kfree_rcu(tunnel, rcu); 1145 end: 1146 return; 1147 } 1148 1149 /* Remove an l2tp session from l2tp_core's hash lists. */ 1150 static void l2tp_session_unhash(struct l2tp_session *session) 1151 { 1152 struct l2tp_tunnel *tunnel = session->tunnel; 1153 1154 /* Remove the session from core hashes */ 1155 if (tunnel) { 1156 /* Remove from the per-tunnel hash */ 1157 write_lock_bh(&tunnel->hlist_lock); 1158 hlist_del_init(&session->hlist); 1159 write_unlock_bh(&tunnel->hlist_lock); 1160 1161 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1162 if (tunnel->version != L2TP_HDR_VER_2) { 1163 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1164 1165 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1166 hlist_del_init_rcu(&session->global_hlist); 1167 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1168 synchronize_rcu(); 1169 } 1170 } 1171 } 1172 1173 /* When the tunnel is closed, all the attached sessions need to go too. 1174 */ 1175 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1176 { 1177 int hash; 1178 struct hlist_node *walk; 1179 struct hlist_node *tmp; 1180 struct l2tp_session *session; 1181 1182 write_lock_bh(&tunnel->hlist_lock); 1183 tunnel->acpt_newsess = false; 1184 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1185 again: 1186 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) { 1187 session = hlist_entry(walk, struct l2tp_session, hlist); 1188 1189 hlist_del_init(&session->hlist); 1190 1191 if (test_and_set_bit(0, &session->dead)) 1192 goto again; 1193 1194 write_unlock_bh(&tunnel->hlist_lock); 1195 1196 l2tp_session_unhash(session); 1197 l2tp_session_queue_purge(session); 1198 1199 if (session->session_close) 1200 (*session->session_close)(session); 1201 1202 l2tp_session_dec_refcount(session); 1203 1204 write_lock_bh(&tunnel->hlist_lock); 1205 1206 /* Now restart from the beginning of this hash 1207 * chain. We always remove a session from the 1208 * list so we are guaranteed to make forward 1209 * progress. 1210 */ 1211 goto again; 1212 } 1213 } 1214 write_unlock_bh(&tunnel->hlist_lock); 1215 } 1216 1217 /* Tunnel socket destroy hook for UDP encapsulation */ 1218 static void l2tp_udp_encap_destroy(struct sock *sk) 1219 { 1220 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1221 1222 if (tunnel) 1223 l2tp_tunnel_delete(tunnel); 1224 } 1225 1226 /* Workqueue tunnel deletion function */ 1227 static void l2tp_tunnel_del_work(struct work_struct *work) 1228 { 1229 struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel, 1230 del_work); 1231 struct sock *sk = tunnel->sock; 1232 struct socket *sock = sk->sk_socket; 1233 struct l2tp_net *pn; 1234 1235 l2tp_tunnel_closeall(tunnel); 1236 1237 /* If the tunnel socket was created within the kernel, use 1238 * the sk API to release it here. 1239 */ 1240 if (tunnel->fd < 0) { 1241 if (sock) { 1242 kernel_sock_shutdown(sock, SHUT_RDWR); 1243 sock_release(sock); 1244 } 1245 } 1246 1247 /* Remove the tunnel struct from the tunnel list */ 1248 pn = l2tp_pernet(tunnel->l2tp_net); 1249 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1250 list_del_rcu(&tunnel->list); 1251 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1252 1253 /* drop initial ref */ 1254 l2tp_tunnel_dec_refcount(tunnel); 1255 1256 /* drop workqueue ref */ 1257 l2tp_tunnel_dec_refcount(tunnel); 1258 } 1259 1260 /* Create a socket for the tunnel, if one isn't set up by 1261 * userspace. This is used for static tunnels where there is no 1262 * managing L2TP daemon. 1263 * 1264 * Since we don't want these sockets to keep a namespace alive by 1265 * themselves, we drop the socket's namespace refcount after creation. 1266 * These sockets are freed when the namespace exits using the pernet 1267 * exit hook. 1268 */ 1269 static int l2tp_tunnel_sock_create(struct net *net, 1270 u32 tunnel_id, 1271 u32 peer_tunnel_id, 1272 struct l2tp_tunnel_cfg *cfg, 1273 struct socket **sockp) 1274 { 1275 int err = -EINVAL; 1276 struct socket *sock = NULL; 1277 struct udp_port_cfg udp_conf; 1278 1279 switch (cfg->encap) { 1280 case L2TP_ENCAPTYPE_UDP: 1281 memset(&udp_conf, 0, sizeof(udp_conf)); 1282 1283 #if IS_ENABLED(CONFIG_IPV6) 1284 if (cfg->local_ip6 && cfg->peer_ip6) { 1285 udp_conf.family = AF_INET6; 1286 memcpy(&udp_conf.local_ip6, cfg->local_ip6, 1287 sizeof(udp_conf.local_ip6)); 1288 memcpy(&udp_conf.peer_ip6, cfg->peer_ip6, 1289 sizeof(udp_conf.peer_ip6)); 1290 udp_conf.use_udp6_tx_checksums = 1291 !cfg->udp6_zero_tx_checksums; 1292 udp_conf.use_udp6_rx_checksums = 1293 !cfg->udp6_zero_rx_checksums; 1294 } else 1295 #endif 1296 { 1297 udp_conf.family = AF_INET; 1298 udp_conf.local_ip = cfg->local_ip; 1299 udp_conf.peer_ip = cfg->peer_ip; 1300 udp_conf.use_udp_checksums = cfg->use_udp_checksums; 1301 } 1302 1303 udp_conf.local_udp_port = htons(cfg->local_udp_port); 1304 udp_conf.peer_udp_port = htons(cfg->peer_udp_port); 1305 1306 err = udp_sock_create(net, &udp_conf, &sock); 1307 if (err < 0) 1308 goto out; 1309 1310 break; 1311 1312 case L2TP_ENCAPTYPE_IP: 1313 #if IS_ENABLED(CONFIG_IPV6) 1314 if (cfg->local_ip6 && cfg->peer_ip6) { 1315 struct sockaddr_l2tpip6 ip6_addr = {0}; 1316 1317 err = sock_create_kern(net, AF_INET6, SOCK_DGRAM, 1318 IPPROTO_L2TP, &sock); 1319 if (err < 0) 1320 goto out; 1321 1322 ip6_addr.l2tp_family = AF_INET6; 1323 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6, 1324 sizeof(ip6_addr.l2tp_addr)); 1325 ip6_addr.l2tp_conn_id = tunnel_id; 1326 err = kernel_bind(sock, (struct sockaddr *)&ip6_addr, 1327 sizeof(ip6_addr)); 1328 if (err < 0) 1329 goto out; 1330 1331 ip6_addr.l2tp_family = AF_INET6; 1332 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6, 1333 sizeof(ip6_addr.l2tp_addr)); 1334 ip6_addr.l2tp_conn_id = peer_tunnel_id; 1335 err = kernel_connect(sock, 1336 (struct sockaddr *)&ip6_addr, 1337 sizeof(ip6_addr), 0); 1338 if (err < 0) 1339 goto out; 1340 } else 1341 #endif 1342 { 1343 struct sockaddr_l2tpip ip_addr = {0}; 1344 1345 err = sock_create_kern(net, AF_INET, SOCK_DGRAM, 1346 IPPROTO_L2TP, &sock); 1347 if (err < 0) 1348 goto out; 1349 1350 ip_addr.l2tp_family = AF_INET; 1351 ip_addr.l2tp_addr = cfg->local_ip; 1352 ip_addr.l2tp_conn_id = tunnel_id; 1353 err = kernel_bind(sock, (struct sockaddr *)&ip_addr, 1354 sizeof(ip_addr)); 1355 if (err < 0) 1356 goto out; 1357 1358 ip_addr.l2tp_family = AF_INET; 1359 ip_addr.l2tp_addr = cfg->peer_ip; 1360 ip_addr.l2tp_conn_id = peer_tunnel_id; 1361 err = kernel_connect(sock, (struct sockaddr *)&ip_addr, 1362 sizeof(ip_addr), 0); 1363 if (err < 0) 1364 goto out; 1365 } 1366 break; 1367 1368 default: 1369 goto out; 1370 } 1371 1372 out: 1373 *sockp = sock; 1374 if (err < 0 && sock) { 1375 kernel_sock_shutdown(sock, SHUT_RDWR); 1376 sock_release(sock); 1377 *sockp = NULL; 1378 } 1379 1380 return err; 1381 } 1382 1383 static struct lock_class_key l2tp_socket_class; 1384 1385 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, 1386 struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp) 1387 { 1388 struct l2tp_tunnel *tunnel = NULL; 1389 int err; 1390 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1391 1392 if (cfg) 1393 encap = cfg->encap; 1394 1395 tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL); 1396 if (!tunnel) { 1397 err = -ENOMEM; 1398 goto err; 1399 } 1400 1401 tunnel->version = version; 1402 tunnel->tunnel_id = tunnel_id; 1403 tunnel->peer_tunnel_id = peer_tunnel_id; 1404 1405 tunnel->magic = L2TP_TUNNEL_MAGIC; 1406 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1407 rwlock_init(&tunnel->hlist_lock); 1408 tunnel->acpt_newsess = true; 1409 1410 tunnel->encap = encap; 1411 1412 refcount_set(&tunnel->ref_count, 1); 1413 tunnel->fd = fd; 1414 1415 /* Init delete workqueue struct */ 1416 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); 1417 1418 INIT_LIST_HEAD(&tunnel->list); 1419 1420 err = 0; 1421 err: 1422 if (tunnelp) 1423 *tunnelp = tunnel; 1424 1425 return err; 1426 } 1427 EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1428 1429 static int l2tp_validate_socket(const struct sock *sk, const struct net *net, 1430 enum l2tp_encap_type encap) 1431 { 1432 if (!net_eq(sock_net(sk), net)) 1433 return -EINVAL; 1434 1435 if (sk->sk_type != SOCK_DGRAM) 1436 return -EPROTONOSUPPORT; 1437 1438 if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6) 1439 return -EPROTONOSUPPORT; 1440 1441 if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) || 1442 (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP)) 1443 return -EPROTONOSUPPORT; 1444 1445 if (sk->sk_user_data) 1446 return -EBUSY; 1447 1448 return 0; 1449 } 1450 1451 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net, 1452 struct l2tp_tunnel_cfg *cfg) 1453 { 1454 struct l2tp_tunnel *tunnel_walk; 1455 struct l2tp_net *pn; 1456 struct socket *sock; 1457 struct sock *sk; 1458 int ret; 1459 1460 if (tunnel->fd < 0) { 1461 ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id, 1462 tunnel->peer_tunnel_id, cfg, 1463 &sock); 1464 if (ret < 0) 1465 goto err; 1466 } else { 1467 sock = sockfd_lookup(tunnel->fd, &ret); 1468 if (!sock) 1469 goto err; 1470 1471 ret = l2tp_validate_socket(sock->sk, net, tunnel->encap); 1472 if (ret < 0) 1473 goto err_sock; 1474 } 1475 1476 tunnel->l2tp_net = net; 1477 pn = l2tp_pernet(net); 1478 1479 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1480 list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) { 1481 if (tunnel_walk->tunnel_id == tunnel->tunnel_id) { 1482 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1483 1484 ret = -EEXIST; 1485 goto err_sock; 1486 } 1487 } 1488 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); 1489 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1490 1491 sk = sock->sk; 1492 sock_hold(sk); 1493 tunnel->sock = sk; 1494 1495 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1496 struct udp_tunnel_sock_cfg udp_cfg = { 1497 .sk_user_data = tunnel, 1498 .encap_type = UDP_ENCAP_L2TPINUDP, 1499 .encap_rcv = l2tp_udp_encap_recv, 1500 .encap_destroy = l2tp_udp_encap_destroy, 1501 }; 1502 1503 setup_udp_tunnel_sock(net, sock, &udp_cfg); 1504 } else { 1505 sk->sk_user_data = tunnel; 1506 } 1507 1508 tunnel->old_sk_destruct = sk->sk_destruct; 1509 sk->sk_destruct = &l2tp_tunnel_destruct; 1510 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, 1511 "l2tp_sock"); 1512 sk->sk_allocation = GFP_ATOMIC; 1513 1514 trace_register_tunnel(tunnel); 1515 1516 if (tunnel->fd >= 0) 1517 sockfd_put(sock); 1518 1519 return 0; 1520 1521 err_sock: 1522 if (tunnel->fd < 0) 1523 sock_release(sock); 1524 else 1525 sockfd_put(sock); 1526 err: 1527 return ret; 1528 } 1529 EXPORT_SYMBOL_GPL(l2tp_tunnel_register); 1530 1531 /* This function is used by the netlink TUNNEL_DELETE command. 1532 */ 1533 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1534 { 1535 if (!test_and_set_bit(0, &tunnel->dead)) { 1536 trace_delete_tunnel(tunnel); 1537 l2tp_tunnel_inc_refcount(tunnel); 1538 queue_work(l2tp_wq, &tunnel->del_work); 1539 } 1540 } 1541 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1542 1543 void l2tp_session_delete(struct l2tp_session *session) 1544 { 1545 if (test_and_set_bit(0, &session->dead)) 1546 return; 1547 1548 trace_delete_session(session); 1549 l2tp_session_unhash(session); 1550 l2tp_session_queue_purge(session); 1551 if (session->session_close) 1552 (*session->session_close)(session); 1553 1554 l2tp_session_dec_refcount(session); 1555 } 1556 EXPORT_SYMBOL_GPL(l2tp_session_delete); 1557 1558 /* We come here whenever a session's send_seq, cookie_len or 1559 * l2specific_type parameters are set. 1560 */ 1561 void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1562 { 1563 if (version == L2TP_HDR_VER_2) { 1564 session->hdr_len = 6; 1565 if (session->send_seq) 1566 session->hdr_len += 4; 1567 } else { 1568 session->hdr_len = 4 + session->cookie_len; 1569 session->hdr_len += l2tp_get_l2specific_len(session); 1570 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1571 session->hdr_len += 4; 1572 } 1573 } 1574 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1575 1576 struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, 1577 u32 peer_session_id, struct l2tp_session_cfg *cfg) 1578 { 1579 struct l2tp_session *session; 1580 1581 session = kzalloc(sizeof(*session) + priv_size, GFP_KERNEL); 1582 if (session) { 1583 session->magic = L2TP_SESSION_MAGIC; 1584 session->tunnel = tunnel; 1585 1586 session->session_id = session_id; 1587 session->peer_session_id = peer_session_id; 1588 session->nr = 0; 1589 if (tunnel->version == L2TP_HDR_VER_2) 1590 session->nr_max = 0xffff; 1591 else 1592 session->nr_max = 0xffffff; 1593 session->nr_window_size = session->nr_max / 2; 1594 session->nr_oos_count_max = 4; 1595 1596 /* Use NR of first received packet */ 1597 session->reorder_skip = 1; 1598 1599 sprintf(&session->name[0], "sess %u/%u", 1600 tunnel->tunnel_id, session->session_id); 1601 1602 skb_queue_head_init(&session->reorder_q); 1603 1604 INIT_HLIST_NODE(&session->hlist); 1605 INIT_HLIST_NODE(&session->global_hlist); 1606 1607 if (cfg) { 1608 session->pwtype = cfg->pw_type; 1609 session->send_seq = cfg->send_seq; 1610 session->recv_seq = cfg->recv_seq; 1611 session->lns_mode = cfg->lns_mode; 1612 session->reorder_timeout = cfg->reorder_timeout; 1613 session->l2specific_type = cfg->l2specific_type; 1614 session->cookie_len = cfg->cookie_len; 1615 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1616 session->peer_cookie_len = cfg->peer_cookie_len; 1617 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1618 } 1619 1620 l2tp_session_set_header_len(session, tunnel->version); 1621 1622 refcount_set(&session->ref_count, 1); 1623 1624 return session; 1625 } 1626 1627 return ERR_PTR(-ENOMEM); 1628 } 1629 EXPORT_SYMBOL_GPL(l2tp_session_create); 1630 1631 /***************************************************************************** 1632 * Init and cleanup 1633 *****************************************************************************/ 1634 1635 static __net_init int l2tp_init_net(struct net *net) 1636 { 1637 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1638 int hash; 1639 1640 INIT_LIST_HEAD(&pn->l2tp_tunnel_list); 1641 spin_lock_init(&pn->l2tp_tunnel_list_lock); 1642 1643 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1644 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1645 1646 spin_lock_init(&pn->l2tp_session_hlist_lock); 1647 1648 return 0; 1649 } 1650 1651 static __net_exit void l2tp_exit_net(struct net *net) 1652 { 1653 struct l2tp_net *pn = l2tp_pernet(net); 1654 struct l2tp_tunnel *tunnel = NULL; 1655 int hash; 1656 1657 rcu_read_lock_bh(); 1658 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 1659 l2tp_tunnel_delete(tunnel); 1660 } 1661 rcu_read_unlock_bh(); 1662 1663 if (l2tp_wq) 1664 flush_workqueue(l2tp_wq); 1665 rcu_barrier(); 1666 1667 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1668 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash])); 1669 } 1670 1671 static struct pernet_operations l2tp_net_ops = { 1672 .init = l2tp_init_net, 1673 .exit = l2tp_exit_net, 1674 .id = &l2tp_net_id, 1675 .size = sizeof(struct l2tp_net), 1676 }; 1677 1678 static int __init l2tp_init(void) 1679 { 1680 int rc = 0; 1681 1682 rc = register_pernet_device(&l2tp_net_ops); 1683 if (rc) 1684 goto out; 1685 1686 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1687 if (!l2tp_wq) { 1688 pr_err("alloc_workqueue failed\n"); 1689 unregister_pernet_device(&l2tp_net_ops); 1690 rc = -ENOMEM; 1691 goto out; 1692 } 1693 1694 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 1695 1696 out: 1697 return rc; 1698 } 1699 1700 static void __exit l2tp_exit(void) 1701 { 1702 unregister_pernet_device(&l2tp_net_ops); 1703 if (l2tp_wq) { 1704 destroy_workqueue(l2tp_wq); 1705 l2tp_wq = NULL; 1706 } 1707 } 1708 1709 module_init(l2tp_init); 1710 module_exit(l2tp_exit); 1711 1712 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 1713 MODULE_DESCRIPTION("L2TP core"); 1714 MODULE_LICENSE("GPL"); 1715 MODULE_VERSION(L2TP_DRV_VERSION); 1716