1 /* 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 * This program is free software; you can redistribute it and/or modify 17 * it under the terms of the GNU General Public License version 2 as 18 * published by the Free Software Foundation. 19 */ 20 21 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 22 23 #include <linux/module.h> 24 #include <linux/string.h> 25 #include <linux/list.h> 26 #include <linux/rculist.h> 27 #include <linux/uaccess.h> 28 29 #include <linux/kernel.h> 30 #include <linux/spinlock.h> 31 #include <linux/kthread.h> 32 #include <linux/sched.h> 33 #include <linux/slab.h> 34 #include <linux/errno.h> 35 #include <linux/jiffies.h> 36 37 #include <linux/netdevice.h> 38 #include <linux/net.h> 39 #include <linux/inetdevice.h> 40 #include <linux/skbuff.h> 41 #include <linux/init.h> 42 #include <linux/in.h> 43 #include <linux/ip.h> 44 #include <linux/udp.h> 45 #include <linux/l2tp.h> 46 #include <linux/hash.h> 47 #include <linux/sort.h> 48 #include <linux/file.h> 49 #include <linux/nsproxy.h> 50 #include <net/net_namespace.h> 51 #include <net/netns/generic.h> 52 #include <net/dst.h> 53 #include <net/ip.h> 54 #include <net/udp.h> 55 #include <net/inet_common.h> 56 #include <net/xfrm.h> 57 #include <net/protocol.h> 58 #include <net/inet6_connection_sock.h> 59 #include <net/inet_ecn.h> 60 #include <net/ip6_route.h> 61 #include <net/ip6_checksum.h> 62 63 #include <asm/byteorder.h> 64 #include <linux/atomic.h> 65 66 #include "l2tp_core.h" 67 68 #define L2TP_DRV_VERSION "V2.0" 69 70 /* L2TP header constants */ 71 #define L2TP_HDRFLAG_T 0x8000 72 #define L2TP_HDRFLAG_L 0x4000 73 #define L2TP_HDRFLAG_S 0x0800 74 #define L2TP_HDRFLAG_O 0x0200 75 #define L2TP_HDRFLAG_P 0x0100 76 77 #define L2TP_HDR_VER_MASK 0x000F 78 #define L2TP_HDR_VER_2 0x0002 79 #define L2TP_HDR_VER_3 0x0003 80 81 /* L2TPv3 default L2-specific sublayer */ 82 #define L2TP_SLFLAG_S 0x40000000 83 #define L2TP_SL_SEQ_MASK 0x00ffffff 84 85 #define L2TP_HDR_SIZE_SEQ 10 86 #define L2TP_HDR_SIZE_NOSEQ 6 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 atomic_t l2tp_tunnel_count; 103 static atomic_t l2tp_session_count; 104 static struct workqueue_struct *l2tp_wq; 105 106 /* per-net private data for this module */ 107 static unsigned int l2tp_net_id; 108 struct l2tp_net { 109 struct list_head l2tp_tunnel_list; 110 spinlock_t l2tp_tunnel_list_lock; 111 struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2]; 112 spinlock_t l2tp_session_hlist_lock; 113 }; 114 115 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel); 116 117 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk) 118 { 119 return sk->sk_user_data; 120 } 121 122 static inline struct l2tp_net *l2tp_pernet(struct net *net) 123 { 124 BUG_ON(!net); 125 126 return net_generic(net, l2tp_net_id); 127 } 128 129 /* Tunnel reference counts. Incremented per session that is added to 130 * the tunnel. 131 */ 132 static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel) 133 { 134 atomic_inc(&tunnel->ref_count); 135 } 136 137 static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel) 138 { 139 if (atomic_dec_and_test(&tunnel->ref_count)) 140 l2tp_tunnel_free(tunnel); 141 } 142 #ifdef L2TP_REFCNT_DEBUG 143 #define l2tp_tunnel_inc_refcount(_t) \ 144 do { \ 145 pr_debug("l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n", \ 146 __func__, __LINE__, (_t)->name, \ 147 atomic_read(&_t->ref_count)); \ 148 l2tp_tunnel_inc_refcount_1(_t); \ 149 } while (0) 150 #define l2tp_tunnel_dec_refcount(_t) 151 do { \ 152 pr_debug("l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n", \ 153 __func__, __LINE__, (_t)->name, \ 154 atomic_read(&_t->ref_count)); \ 155 l2tp_tunnel_dec_refcount_1(_t); \ 156 } while (0) 157 #else 158 #define l2tp_tunnel_inc_refcount(t) l2tp_tunnel_inc_refcount_1(t) 159 #define l2tp_tunnel_dec_refcount(t) l2tp_tunnel_dec_refcount_1(t) 160 #endif 161 162 /* Session hash global list for L2TPv3. 163 * The session_id SHOULD be random according to RFC3931, but several 164 * L2TP implementations use incrementing session_ids. So we do a real 165 * hash on the session_id, rather than a simple bitmask. 166 */ 167 static inline struct hlist_head * 168 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id) 169 { 170 return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)]; 171 172 } 173 174 /* Lookup the tunnel socket, possibly involving the fs code if the socket is 175 * owned by userspace. A struct sock returned from this function must be 176 * released using l2tp_tunnel_sock_put once you're done with it. 177 */ 178 static struct sock *l2tp_tunnel_sock_lookup(struct l2tp_tunnel *tunnel) 179 { 180 int err = 0; 181 struct socket *sock = NULL; 182 struct sock *sk = NULL; 183 184 if (!tunnel) 185 goto out; 186 187 if (tunnel->fd >= 0) { 188 /* Socket is owned by userspace, who might be in the process 189 * of closing it. Look the socket up using the fd to ensure 190 * consistency. 191 */ 192 sock = sockfd_lookup(tunnel->fd, &err); 193 if (sock) 194 sk = sock->sk; 195 } else { 196 /* Socket is owned by kernelspace */ 197 sk = tunnel->sock; 198 sock_hold(sk); 199 } 200 201 out: 202 return sk; 203 } 204 205 /* Drop a reference to a tunnel socket obtained via. l2tp_tunnel_sock_put */ 206 static void l2tp_tunnel_sock_put(struct sock *sk) 207 { 208 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk); 209 if (tunnel) { 210 if (tunnel->fd >= 0) { 211 /* Socket is owned by userspace */ 212 sockfd_put(sk->sk_socket); 213 } 214 sock_put(sk); 215 } 216 sock_put(sk); 217 } 218 219 /* Lookup a session by id in the global session list 220 */ 221 static struct l2tp_session *l2tp_session_find_2(struct net *net, u32 session_id) 222 { 223 struct l2tp_net *pn = l2tp_pernet(net); 224 struct hlist_head *session_list = 225 l2tp_session_id_hash_2(pn, session_id); 226 struct l2tp_session *session; 227 228 rcu_read_lock_bh(); 229 hlist_for_each_entry_rcu(session, session_list, global_hlist) { 230 if (session->session_id == session_id) { 231 rcu_read_unlock_bh(); 232 return session; 233 } 234 } 235 rcu_read_unlock_bh(); 236 237 return NULL; 238 } 239 240 /* Session hash list. 241 * The session_id SHOULD be random according to RFC2661, but several 242 * L2TP implementations (Cisco and Microsoft) use incrementing 243 * session_ids. So we do a real hash on the session_id, rather than a 244 * simple bitmask. 245 */ 246 static inline struct hlist_head * 247 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id) 248 { 249 return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)]; 250 } 251 252 /* Lookup a session by id 253 */ 254 struct l2tp_session *l2tp_session_find(struct net *net, struct l2tp_tunnel *tunnel, u32 session_id) 255 { 256 struct hlist_head *session_list; 257 struct l2tp_session *session; 258 259 /* In L2TPv3, session_ids are unique over all tunnels and we 260 * sometimes need to look them up before we know the 261 * tunnel. 262 */ 263 if (tunnel == NULL) 264 return l2tp_session_find_2(net, session_id); 265 266 session_list = l2tp_session_id_hash(tunnel, session_id); 267 read_lock_bh(&tunnel->hlist_lock); 268 hlist_for_each_entry(session, session_list, hlist) { 269 if (session->session_id == session_id) { 270 read_unlock_bh(&tunnel->hlist_lock); 271 return session; 272 } 273 } 274 read_unlock_bh(&tunnel->hlist_lock); 275 276 return NULL; 277 } 278 EXPORT_SYMBOL_GPL(l2tp_session_find); 279 280 struct l2tp_session *l2tp_session_find_nth(struct l2tp_tunnel *tunnel, int nth) 281 { 282 int hash; 283 struct l2tp_session *session; 284 int count = 0; 285 286 read_lock_bh(&tunnel->hlist_lock); 287 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 288 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) { 289 if (++count > nth) { 290 read_unlock_bh(&tunnel->hlist_lock); 291 return session; 292 } 293 } 294 } 295 296 read_unlock_bh(&tunnel->hlist_lock); 297 298 return NULL; 299 } 300 EXPORT_SYMBOL_GPL(l2tp_session_find_nth); 301 302 /* Lookup a session by interface name. 303 * This is very inefficient but is only used by management interfaces. 304 */ 305 struct l2tp_session *l2tp_session_find_by_ifname(struct net *net, char *ifname) 306 { 307 struct l2tp_net *pn = l2tp_pernet(net); 308 int hash; 309 struct l2tp_session *session; 310 311 rcu_read_lock_bh(); 312 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) { 313 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) { 314 if (!strcmp(session->ifname, ifname)) { 315 rcu_read_unlock_bh(); 316 return session; 317 } 318 } 319 } 320 321 rcu_read_unlock_bh(); 322 323 return NULL; 324 } 325 EXPORT_SYMBOL_GPL(l2tp_session_find_by_ifname); 326 327 /* Lookup a tunnel by id 328 */ 329 struct l2tp_tunnel *l2tp_tunnel_find(struct net *net, u32 tunnel_id) 330 { 331 struct l2tp_tunnel *tunnel; 332 struct l2tp_net *pn = l2tp_pernet(net); 333 334 rcu_read_lock_bh(); 335 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 336 if (tunnel->tunnel_id == tunnel_id) { 337 rcu_read_unlock_bh(); 338 return tunnel; 339 } 340 } 341 rcu_read_unlock_bh(); 342 343 return NULL; 344 } 345 EXPORT_SYMBOL_GPL(l2tp_tunnel_find); 346 347 struct l2tp_tunnel *l2tp_tunnel_find_nth(struct net *net, int nth) 348 { 349 struct l2tp_net *pn = l2tp_pernet(net); 350 struct l2tp_tunnel *tunnel; 351 int count = 0; 352 353 rcu_read_lock_bh(); 354 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 355 if (++count > nth) { 356 rcu_read_unlock_bh(); 357 return tunnel; 358 } 359 } 360 361 rcu_read_unlock_bh(); 362 363 return NULL; 364 } 365 EXPORT_SYMBOL_GPL(l2tp_tunnel_find_nth); 366 367 /***************************************************************************** 368 * Receive data handling 369 *****************************************************************************/ 370 371 /* Queue a skb in order. We come here only if the skb has an L2TP sequence 372 * number. 373 */ 374 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb) 375 { 376 struct sk_buff *skbp; 377 struct sk_buff *tmp; 378 u32 ns = L2TP_SKB_CB(skb)->ns; 379 380 spin_lock_bh(&session->reorder_q.lock); 381 skb_queue_walk_safe(&session->reorder_q, skbp, tmp) { 382 if (L2TP_SKB_CB(skbp)->ns > ns) { 383 __skb_queue_before(&session->reorder_q, skbp, skb); 384 l2tp_dbg(session, L2TP_MSG_SEQ, 385 "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n", 386 session->name, ns, L2TP_SKB_CB(skbp)->ns, 387 skb_queue_len(&session->reorder_q)); 388 atomic_long_inc(&session->stats.rx_oos_packets); 389 goto out; 390 } 391 } 392 393 __skb_queue_tail(&session->reorder_q, skb); 394 395 out: 396 spin_unlock_bh(&session->reorder_q.lock); 397 } 398 399 /* Dequeue a single skb. 400 */ 401 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb) 402 { 403 struct l2tp_tunnel *tunnel = session->tunnel; 404 int length = L2TP_SKB_CB(skb)->length; 405 406 /* We're about to requeue the skb, so return resources 407 * to its current owner (a socket receive buffer). 408 */ 409 skb_orphan(skb); 410 411 atomic_long_inc(&tunnel->stats.rx_packets); 412 atomic_long_add(length, &tunnel->stats.rx_bytes); 413 atomic_long_inc(&session->stats.rx_packets); 414 atomic_long_add(length, &session->stats.rx_bytes); 415 416 if (L2TP_SKB_CB(skb)->has_seq) { 417 /* Bump our Nr */ 418 session->nr++; 419 session->nr &= session->nr_max; 420 421 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n", 422 session->name, session->nr); 423 } 424 425 /* call private receive handler */ 426 if (session->recv_skb != NULL) 427 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length); 428 else 429 kfree_skb(skb); 430 431 if (session->deref) 432 (*session->deref)(session); 433 } 434 435 /* Dequeue skbs from the session's reorder_q, subject to packet order. 436 * Skbs that have been in the queue for too long are simply discarded. 437 */ 438 static void l2tp_recv_dequeue(struct l2tp_session *session) 439 { 440 struct sk_buff *skb; 441 struct sk_buff *tmp; 442 443 /* If the pkt at the head of the queue has the nr that we 444 * expect to send up next, dequeue it and any other 445 * in-sequence packets behind it. 446 */ 447 start: 448 spin_lock_bh(&session->reorder_q.lock); 449 skb_queue_walk_safe(&session->reorder_q, skb, tmp) { 450 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) { 451 atomic_long_inc(&session->stats.rx_seq_discards); 452 atomic_long_inc(&session->stats.rx_errors); 453 l2tp_dbg(session, L2TP_MSG_SEQ, 454 "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n", 455 session->name, L2TP_SKB_CB(skb)->ns, 456 L2TP_SKB_CB(skb)->length, session->nr, 457 skb_queue_len(&session->reorder_q)); 458 session->reorder_skip = 1; 459 __skb_unlink(skb, &session->reorder_q); 460 kfree_skb(skb); 461 if (session->deref) 462 (*session->deref)(session); 463 continue; 464 } 465 466 if (L2TP_SKB_CB(skb)->has_seq) { 467 if (session->reorder_skip) { 468 l2tp_dbg(session, L2TP_MSG_SEQ, 469 "%s: advancing nr to next pkt: %u -> %u", 470 session->name, session->nr, 471 L2TP_SKB_CB(skb)->ns); 472 session->reorder_skip = 0; 473 session->nr = L2TP_SKB_CB(skb)->ns; 474 } 475 if (L2TP_SKB_CB(skb)->ns != session->nr) { 476 l2tp_dbg(session, L2TP_MSG_SEQ, 477 "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n", 478 session->name, L2TP_SKB_CB(skb)->ns, 479 L2TP_SKB_CB(skb)->length, session->nr, 480 skb_queue_len(&session->reorder_q)); 481 goto out; 482 } 483 } 484 __skb_unlink(skb, &session->reorder_q); 485 486 /* Process the skb. We release the queue lock while we 487 * do so to let other contexts process the queue. 488 */ 489 spin_unlock_bh(&session->reorder_q.lock); 490 l2tp_recv_dequeue_skb(session, skb); 491 goto start; 492 } 493 494 out: 495 spin_unlock_bh(&session->reorder_q.lock); 496 } 497 498 static inline int l2tp_verify_udp_checksum(struct sock *sk, 499 struct sk_buff *skb) 500 { 501 struct udphdr *uh = udp_hdr(skb); 502 u16 ulen = ntohs(uh->len); 503 __wsum psum; 504 505 if (sk->sk_no_check || skb_csum_unnecessary(skb)) 506 return 0; 507 508 #if IS_ENABLED(CONFIG_IPV6) 509 if (sk->sk_family == PF_INET6 && !l2tp_tunnel(sk)->v4mapped) { 510 if (!uh->check) { 511 LIMIT_NETDEBUG(KERN_INFO "L2TP: IPv6: checksum is 0\n"); 512 return 1; 513 } 514 if ((skb->ip_summed == CHECKSUM_COMPLETE) && 515 !csum_ipv6_magic(&ipv6_hdr(skb)->saddr, 516 &ipv6_hdr(skb)->daddr, ulen, 517 IPPROTO_UDP, skb->csum)) { 518 skb->ip_summed = CHECKSUM_UNNECESSARY; 519 return 0; 520 } 521 skb->csum = ~csum_unfold(csum_ipv6_magic(&ipv6_hdr(skb)->saddr, 522 &ipv6_hdr(skb)->daddr, 523 skb->len, IPPROTO_UDP, 524 0)); 525 } else 526 #endif 527 { 528 struct inet_sock *inet; 529 if (!uh->check) 530 return 0; 531 inet = inet_sk(sk); 532 psum = csum_tcpudp_nofold(inet->inet_saddr, inet->inet_daddr, 533 ulen, IPPROTO_UDP, 0); 534 535 if ((skb->ip_summed == CHECKSUM_COMPLETE) && 536 !csum_fold(csum_add(psum, skb->csum))) 537 return 0; 538 skb->csum = psum; 539 } 540 541 return __skb_checksum_complete(skb); 542 } 543 544 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr) 545 { 546 u32 nws; 547 548 if (nr >= session->nr) 549 nws = nr - session->nr; 550 else 551 nws = (session->nr_max + 1) - (session->nr - nr); 552 553 return nws < session->nr_window_size; 554 } 555 556 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if 557 * acceptable, else non-zero. 558 */ 559 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb) 560 { 561 if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) { 562 /* Packet sequence number is outside allowed window. 563 * Discard it. 564 */ 565 l2tp_dbg(session, L2TP_MSG_SEQ, 566 "%s: pkt %u len %d discarded, outside window, nr=%u\n", 567 session->name, L2TP_SKB_CB(skb)->ns, 568 L2TP_SKB_CB(skb)->length, session->nr); 569 goto discard; 570 } 571 572 if (session->reorder_timeout != 0) { 573 /* Packet reordering enabled. Add skb to session's 574 * reorder queue, in order of ns. 575 */ 576 l2tp_recv_queue_skb(session, skb); 577 goto out; 578 } 579 580 /* Packet reordering disabled. Discard out-of-sequence packets, while 581 * tracking the number if in-sequence packets after the first OOS packet 582 * is seen. After nr_oos_count_max in-sequence packets, reset the 583 * sequence number to re-enable packet reception. 584 */ 585 if (L2TP_SKB_CB(skb)->ns == session->nr) { 586 skb_queue_tail(&session->reorder_q, skb); 587 } else { 588 u32 nr_oos = L2TP_SKB_CB(skb)->ns; 589 u32 nr_next = (session->nr_oos + 1) & session->nr_max; 590 591 if (nr_oos == nr_next) 592 session->nr_oos_count++; 593 else 594 session->nr_oos_count = 0; 595 596 session->nr_oos = nr_oos; 597 if (session->nr_oos_count > session->nr_oos_count_max) { 598 session->reorder_skip = 1; 599 l2tp_dbg(session, L2TP_MSG_SEQ, 600 "%s: %d oos packets received. Resetting sequence numbers\n", 601 session->name, session->nr_oos_count); 602 } 603 if (!session->reorder_skip) { 604 atomic_long_inc(&session->stats.rx_seq_discards); 605 l2tp_dbg(session, L2TP_MSG_SEQ, 606 "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n", 607 session->name, L2TP_SKB_CB(skb)->ns, 608 L2TP_SKB_CB(skb)->length, session->nr, 609 skb_queue_len(&session->reorder_q)); 610 goto discard; 611 } 612 skb_queue_tail(&session->reorder_q, skb); 613 } 614 615 out: 616 return 0; 617 618 discard: 619 return 1; 620 } 621 622 /* Do receive processing of L2TP data frames. We handle both L2TPv2 623 * and L2TPv3 data frames here. 624 * 625 * L2TPv2 Data Message Header 626 * 627 * 0 1 2 3 628 * 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 1 629 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 630 * |T|L|x|x|S|x|O|P|x|x|x|x| Ver | Length (opt) | 631 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 632 * | Tunnel ID | Session ID | 633 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 634 * | Ns (opt) | Nr (opt) | 635 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 636 * | Offset Size (opt) | Offset pad... (opt) 637 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 638 * 639 * Data frames are marked by T=0. All other fields are the same as 640 * those in L2TP control frames. 641 * 642 * L2TPv3 Data Message Header 643 * 644 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 645 * | L2TP Session Header | 646 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 647 * | L2-Specific Sublayer | 648 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 649 * | Tunnel Payload ... 650 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 651 * 652 * L2TPv3 Session Header Over IP 653 * 654 * 0 1 2 3 655 * 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 1 656 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 657 * | Session ID | 658 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 659 * | Cookie (optional, maximum 64 bits)... 660 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 661 * | 662 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 663 * 664 * L2TPv3 L2-Specific Sublayer Format 665 * 666 * 0 1 2 3 667 * 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 1 668 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 669 * |x|S|x|x|x|x|x|x| Sequence Number | 670 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 671 * 672 * Cookie value, sublayer format and offset (pad) are negotiated with 673 * the peer when the session is set up. Unlike L2TPv2, we do not need 674 * to parse the packet header to determine if optional fields are 675 * present. 676 * 677 * Caller must already have parsed the frame and determined that it is 678 * a data (not control) frame before coming here. Fields up to the 679 * session-id have already been parsed and ptr points to the data 680 * after the session-id. 681 */ 682 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb, 683 unsigned char *ptr, unsigned char *optr, u16 hdrflags, 684 int length, int (*payload_hook)(struct sk_buff *skb)) 685 { 686 struct l2tp_tunnel *tunnel = session->tunnel; 687 int offset; 688 u32 ns, nr; 689 690 /* The ref count is increased since we now hold a pointer to 691 * the session. Take care to decrement the refcnt when exiting 692 * this function from now on... 693 */ 694 l2tp_session_inc_refcount(session); 695 if (session->ref) 696 (*session->ref)(session); 697 698 /* Parse and check optional cookie */ 699 if (session->peer_cookie_len > 0) { 700 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) { 701 l2tp_info(tunnel, L2TP_MSG_DATA, 702 "%s: cookie mismatch (%u/%u). Discarding.\n", 703 tunnel->name, tunnel->tunnel_id, 704 session->session_id); 705 atomic_long_inc(&session->stats.rx_cookie_discards); 706 goto discard; 707 } 708 ptr += session->peer_cookie_len; 709 } 710 711 /* Handle the optional sequence numbers. Sequence numbers are 712 * in different places for L2TPv2 and L2TPv3. 713 * 714 * If we are the LAC, enable/disable sequence numbers under 715 * the control of the LNS. If no sequence numbers present but 716 * we were expecting them, discard frame. 717 */ 718 ns = nr = 0; 719 L2TP_SKB_CB(skb)->has_seq = 0; 720 if (tunnel->version == L2TP_HDR_VER_2) { 721 if (hdrflags & L2TP_HDRFLAG_S) { 722 ns = ntohs(*(__be16 *) ptr); 723 ptr += 2; 724 nr = ntohs(*(__be16 *) ptr); 725 ptr += 2; 726 727 /* Store L2TP info in the skb */ 728 L2TP_SKB_CB(skb)->ns = ns; 729 L2TP_SKB_CB(skb)->has_seq = 1; 730 731 l2tp_dbg(session, L2TP_MSG_SEQ, 732 "%s: recv data ns=%u, nr=%u, session nr=%u\n", 733 session->name, ns, nr, session->nr); 734 } 735 } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 736 u32 l2h = ntohl(*(__be32 *) ptr); 737 738 if (l2h & 0x40000000) { 739 ns = l2h & 0x00ffffff; 740 741 /* Store L2TP info in the skb */ 742 L2TP_SKB_CB(skb)->ns = ns; 743 L2TP_SKB_CB(skb)->has_seq = 1; 744 745 l2tp_dbg(session, L2TP_MSG_SEQ, 746 "%s: recv data ns=%u, session nr=%u\n", 747 session->name, ns, session->nr); 748 } 749 } 750 751 /* Advance past L2-specific header, if present */ 752 ptr += session->l2specific_len; 753 754 if (L2TP_SKB_CB(skb)->has_seq) { 755 /* Received a packet with sequence numbers. If we're the LNS, 756 * check if we sre sending sequence numbers and if not, 757 * configure it so. 758 */ 759 if ((!session->lns_mode) && (!session->send_seq)) { 760 l2tp_info(session, L2TP_MSG_SEQ, 761 "%s: requested to enable seq numbers by LNS\n", 762 session->name); 763 session->send_seq = -1; 764 l2tp_session_set_header_len(session, tunnel->version); 765 } 766 } else { 767 /* No sequence numbers. 768 * If user has configured mandatory sequence numbers, discard. 769 */ 770 if (session->recv_seq) { 771 l2tp_warn(session, L2TP_MSG_SEQ, 772 "%s: recv data has no seq numbers when required. Discarding.\n", 773 session->name); 774 atomic_long_inc(&session->stats.rx_seq_discards); 775 goto discard; 776 } 777 778 /* If we're the LAC and we're sending sequence numbers, the 779 * LNS has requested that we no longer send sequence numbers. 780 * If we're the LNS and we're sending sequence numbers, the 781 * LAC is broken. Discard the frame. 782 */ 783 if ((!session->lns_mode) && (session->send_seq)) { 784 l2tp_info(session, L2TP_MSG_SEQ, 785 "%s: requested to disable seq numbers by LNS\n", 786 session->name); 787 session->send_seq = 0; 788 l2tp_session_set_header_len(session, tunnel->version); 789 } else if (session->send_seq) { 790 l2tp_warn(session, L2TP_MSG_SEQ, 791 "%s: recv data has no seq numbers when required. Discarding.\n", 792 session->name); 793 atomic_long_inc(&session->stats.rx_seq_discards); 794 goto discard; 795 } 796 } 797 798 /* Session data offset is handled differently for L2TPv2 and 799 * L2TPv3. For L2TPv2, there is an optional 16-bit value in 800 * the header. For L2TPv3, the offset is negotiated using AVPs 801 * in the session setup control protocol. 802 */ 803 if (tunnel->version == L2TP_HDR_VER_2) { 804 /* If offset bit set, skip it. */ 805 if (hdrflags & L2TP_HDRFLAG_O) { 806 offset = ntohs(*(__be16 *)ptr); 807 ptr += 2 + offset; 808 } 809 } else 810 ptr += session->offset; 811 812 offset = ptr - optr; 813 if (!pskb_may_pull(skb, offset)) 814 goto discard; 815 816 __skb_pull(skb, offset); 817 818 /* If caller wants to process the payload before we queue the 819 * packet, do so now. 820 */ 821 if (payload_hook) 822 if ((*payload_hook)(skb)) 823 goto discard; 824 825 /* Prepare skb for adding to the session's reorder_q. Hold 826 * packets for max reorder_timeout or 1 second if not 827 * reordering. 828 */ 829 L2TP_SKB_CB(skb)->length = length; 830 L2TP_SKB_CB(skb)->expires = jiffies + 831 (session->reorder_timeout ? session->reorder_timeout : HZ); 832 833 /* Add packet to the session's receive queue. Reordering is done here, if 834 * enabled. Saved L2TP protocol info is stored in skb->sb[]. 835 */ 836 if (L2TP_SKB_CB(skb)->has_seq) { 837 if (l2tp_recv_data_seq(session, skb)) 838 goto discard; 839 } else { 840 /* No sequence numbers. Add the skb to the tail of the 841 * reorder queue. This ensures that it will be 842 * delivered after all previous sequenced skbs. 843 */ 844 skb_queue_tail(&session->reorder_q, skb); 845 } 846 847 /* Try to dequeue as many skbs from reorder_q as we can. */ 848 l2tp_recv_dequeue(session); 849 850 l2tp_session_dec_refcount(session); 851 852 return; 853 854 discard: 855 atomic_long_inc(&session->stats.rx_errors); 856 kfree_skb(skb); 857 858 if (session->deref) 859 (*session->deref)(session); 860 861 l2tp_session_dec_refcount(session); 862 } 863 EXPORT_SYMBOL(l2tp_recv_common); 864 865 /* Drop skbs from the session's reorder_q 866 */ 867 int l2tp_session_queue_purge(struct l2tp_session *session) 868 { 869 struct sk_buff *skb = NULL; 870 BUG_ON(!session); 871 BUG_ON(session->magic != L2TP_SESSION_MAGIC); 872 while ((skb = skb_dequeue(&session->reorder_q))) { 873 atomic_long_inc(&session->stats.rx_errors); 874 kfree_skb(skb); 875 if (session->deref) 876 (*session->deref)(session); 877 } 878 return 0; 879 } 880 EXPORT_SYMBOL_GPL(l2tp_session_queue_purge); 881 882 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame 883 * here. The skb is not on a list when we get here. 884 * Returns 0 if the packet was a data packet and was successfully passed on. 885 * Returns 1 if the packet was not a good data packet and could not be 886 * forwarded. All such packets are passed up to userspace to deal with. 887 */ 888 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb, 889 int (*payload_hook)(struct sk_buff *skb)) 890 { 891 struct l2tp_session *session = NULL; 892 unsigned char *ptr, *optr; 893 u16 hdrflags; 894 u32 tunnel_id, session_id; 895 u16 version; 896 int length; 897 898 if (tunnel->sock && l2tp_verify_udp_checksum(tunnel->sock, skb)) 899 goto discard_bad_csum; 900 901 /* UDP always verifies the packet length. */ 902 __skb_pull(skb, sizeof(struct udphdr)); 903 904 /* Short packet? */ 905 if (!pskb_may_pull(skb, L2TP_HDR_SIZE_SEQ)) { 906 l2tp_info(tunnel, L2TP_MSG_DATA, 907 "%s: recv short packet (len=%d)\n", 908 tunnel->name, skb->len); 909 goto error; 910 } 911 912 /* Trace packet contents, if enabled */ 913 if (tunnel->debug & L2TP_MSG_DATA) { 914 length = min(32u, skb->len); 915 if (!pskb_may_pull(skb, length)) 916 goto error; 917 918 pr_debug("%s: recv\n", tunnel->name); 919 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length); 920 } 921 922 /* Point to L2TP header */ 923 optr = ptr = skb->data; 924 925 /* Get L2TP header flags */ 926 hdrflags = ntohs(*(__be16 *) ptr); 927 928 /* Check protocol version */ 929 version = hdrflags & L2TP_HDR_VER_MASK; 930 if (version != tunnel->version) { 931 l2tp_info(tunnel, L2TP_MSG_DATA, 932 "%s: recv protocol version mismatch: got %d expected %d\n", 933 tunnel->name, version, tunnel->version); 934 goto error; 935 } 936 937 /* Get length of L2TP packet */ 938 length = skb->len; 939 940 /* If type is control packet, it is handled by userspace. */ 941 if (hdrflags & L2TP_HDRFLAG_T) { 942 l2tp_dbg(tunnel, L2TP_MSG_DATA, 943 "%s: recv control packet, len=%d\n", 944 tunnel->name, length); 945 goto error; 946 } 947 948 /* Skip flags */ 949 ptr += 2; 950 951 if (tunnel->version == L2TP_HDR_VER_2) { 952 /* If length is present, skip it */ 953 if (hdrflags & L2TP_HDRFLAG_L) 954 ptr += 2; 955 956 /* Extract tunnel and session ID */ 957 tunnel_id = ntohs(*(__be16 *) ptr); 958 ptr += 2; 959 session_id = ntohs(*(__be16 *) ptr); 960 ptr += 2; 961 } else { 962 ptr += 2; /* skip reserved bits */ 963 tunnel_id = tunnel->tunnel_id; 964 session_id = ntohl(*(__be32 *) ptr); 965 ptr += 4; 966 } 967 968 /* Find the session context */ 969 session = l2tp_session_find(tunnel->l2tp_net, tunnel, session_id); 970 if (!session || !session->recv_skb) { 971 /* Not found? Pass to userspace to deal with */ 972 l2tp_info(tunnel, L2TP_MSG_DATA, 973 "%s: no session found (%u/%u). Passing up.\n", 974 tunnel->name, tunnel_id, session_id); 975 goto error; 976 } 977 978 l2tp_recv_common(session, skb, ptr, optr, hdrflags, length, payload_hook); 979 980 return 0; 981 982 discard_bad_csum: 983 LIMIT_NETDEBUG("%s: UDP: bad checksum\n", tunnel->name); 984 UDP_INC_STATS_USER(tunnel->l2tp_net, UDP_MIB_INERRORS, 0); 985 atomic_long_inc(&tunnel->stats.rx_errors); 986 kfree_skb(skb); 987 988 return 0; 989 990 error: 991 /* Put UDP header back */ 992 __skb_push(skb, sizeof(struct udphdr)); 993 994 return 1; 995 } 996 997 /* UDP encapsulation receive handler. See net/ipv4/udp.c. 998 * Return codes: 999 * 0 : success. 1000 * <0: error 1001 * >0: skb should be passed up to userspace as UDP. 1002 */ 1003 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb) 1004 { 1005 struct l2tp_tunnel *tunnel; 1006 1007 tunnel = l2tp_sock_to_tunnel(sk); 1008 if (tunnel == NULL) 1009 goto pass_up; 1010 1011 l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n", 1012 tunnel->name, skb->len); 1013 1014 if (l2tp_udp_recv_core(tunnel, skb, tunnel->recv_payload_hook)) 1015 goto pass_up_put; 1016 1017 sock_put(sk); 1018 return 0; 1019 1020 pass_up_put: 1021 sock_put(sk); 1022 pass_up: 1023 return 1; 1024 } 1025 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv); 1026 1027 /************************************************************************ 1028 * Transmit handling 1029 ***********************************************************************/ 1030 1031 /* Build an L2TP header for the session into the buffer provided. 1032 */ 1033 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf) 1034 { 1035 struct l2tp_tunnel *tunnel = session->tunnel; 1036 __be16 *bufp = buf; 1037 __be16 *optr = buf; 1038 u16 flags = L2TP_HDR_VER_2; 1039 u32 tunnel_id = tunnel->peer_tunnel_id; 1040 u32 session_id = session->peer_session_id; 1041 1042 if (session->send_seq) 1043 flags |= L2TP_HDRFLAG_S; 1044 1045 /* Setup L2TP header. */ 1046 *bufp++ = htons(flags); 1047 *bufp++ = htons(tunnel_id); 1048 *bufp++ = htons(session_id); 1049 if (session->send_seq) { 1050 *bufp++ = htons(session->ns); 1051 *bufp++ = 0; 1052 session->ns++; 1053 session->ns &= 0xffff; 1054 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n", 1055 session->name, session->ns); 1056 } 1057 1058 return bufp - optr; 1059 } 1060 1061 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf) 1062 { 1063 struct l2tp_tunnel *tunnel = session->tunnel; 1064 char *bufp = buf; 1065 char *optr = bufp; 1066 1067 /* Setup L2TP header. The header differs slightly for UDP and 1068 * IP encapsulations. For UDP, there is 4 bytes of flags. 1069 */ 1070 if (tunnel->encap == L2TP_ENCAPTYPE_UDP) { 1071 u16 flags = L2TP_HDR_VER_3; 1072 *((__be16 *) bufp) = htons(flags); 1073 bufp += 2; 1074 *((__be16 *) bufp) = 0; 1075 bufp += 2; 1076 } 1077 1078 *((__be32 *) bufp) = htonl(session->peer_session_id); 1079 bufp += 4; 1080 if (session->cookie_len) { 1081 memcpy(bufp, &session->cookie[0], session->cookie_len); 1082 bufp += session->cookie_len; 1083 } 1084 if (session->l2specific_len) { 1085 if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) { 1086 u32 l2h = 0; 1087 if (session->send_seq) { 1088 l2h = 0x40000000 | session->ns; 1089 session->ns++; 1090 session->ns &= 0xffffff; 1091 l2tp_dbg(session, L2TP_MSG_SEQ, 1092 "%s: updated ns to %u\n", 1093 session->name, session->ns); 1094 } 1095 1096 *((__be32 *) bufp) = htonl(l2h); 1097 } 1098 bufp += session->l2specific_len; 1099 } 1100 if (session->offset) 1101 bufp += session->offset; 1102 1103 return bufp - optr; 1104 } 1105 1106 static int l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb, 1107 struct flowi *fl, size_t data_len) 1108 { 1109 struct l2tp_tunnel *tunnel = session->tunnel; 1110 unsigned int len = skb->len; 1111 int error; 1112 1113 /* Debug */ 1114 if (session->send_seq) 1115 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes, ns=%u\n", 1116 session->name, data_len, session->ns - 1); 1117 else 1118 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %Zd bytes\n", 1119 session->name, data_len); 1120 1121 if (session->debug & L2TP_MSG_DATA) { 1122 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1123 unsigned char *datap = skb->data + uhlen; 1124 1125 pr_debug("%s: xmit\n", session->name); 1126 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, 1127 datap, min_t(size_t, 32, len - uhlen)); 1128 } 1129 1130 /* Queue the packet to IP for output */ 1131 skb->local_df = 1; 1132 #if IS_ENABLED(CONFIG_IPV6) 1133 if (tunnel->sock->sk_family == PF_INET6 && !tunnel->v4mapped) 1134 error = inet6_csk_xmit(skb, NULL); 1135 else 1136 #endif 1137 error = ip_queue_xmit(skb, fl); 1138 1139 /* Update stats */ 1140 if (error >= 0) { 1141 atomic_long_inc(&tunnel->stats.tx_packets); 1142 atomic_long_add(len, &tunnel->stats.tx_bytes); 1143 atomic_long_inc(&session->stats.tx_packets); 1144 atomic_long_add(len, &session->stats.tx_bytes); 1145 } else { 1146 atomic_long_inc(&tunnel->stats.tx_errors); 1147 atomic_long_inc(&session->stats.tx_errors); 1148 } 1149 1150 return 0; 1151 } 1152 1153 #if IS_ENABLED(CONFIG_IPV6) 1154 static void l2tp_xmit_ipv6_csum(struct sock *sk, struct sk_buff *skb, 1155 int udp_len) 1156 { 1157 struct ipv6_pinfo *np = inet6_sk(sk); 1158 struct udphdr *uh = udp_hdr(skb); 1159 1160 if (!skb_dst(skb) || !skb_dst(skb)->dev || 1161 !(skb_dst(skb)->dev->features & NETIF_F_IPV6_CSUM)) { 1162 __wsum csum = skb_checksum(skb, 0, udp_len, 0); 1163 skb->ip_summed = CHECKSUM_UNNECESSARY; 1164 uh->check = csum_ipv6_magic(&np->saddr, &sk->sk_v6_daddr, udp_len, 1165 IPPROTO_UDP, csum); 1166 if (uh->check == 0) 1167 uh->check = CSUM_MANGLED_0; 1168 } else { 1169 skb->ip_summed = CHECKSUM_PARTIAL; 1170 skb->csum_start = skb_transport_header(skb) - skb->head; 1171 skb->csum_offset = offsetof(struct udphdr, check); 1172 uh->check = ~csum_ipv6_magic(&np->saddr, &sk->sk_v6_daddr, 1173 udp_len, IPPROTO_UDP, 0); 1174 } 1175 } 1176 #endif 1177 1178 /* If caller requires the skb to have a ppp header, the header must be 1179 * inserted in the skb data before calling this function. 1180 */ 1181 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len) 1182 { 1183 int data_len = skb->len; 1184 struct l2tp_tunnel *tunnel = session->tunnel; 1185 struct sock *sk = tunnel->sock; 1186 struct flowi *fl; 1187 struct udphdr *uh; 1188 struct inet_sock *inet; 1189 __wsum csum; 1190 int headroom; 1191 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0; 1192 int udp_len; 1193 int ret = NET_XMIT_SUCCESS; 1194 1195 /* Check that there's enough headroom in the skb to insert IP, 1196 * UDP and L2TP headers. If not enough, expand it to 1197 * make room. Adjust truesize. 1198 */ 1199 headroom = NET_SKB_PAD + sizeof(struct iphdr) + 1200 uhlen + hdr_len; 1201 if (skb_cow_head(skb, headroom)) { 1202 kfree_skb(skb); 1203 return NET_XMIT_DROP; 1204 } 1205 1206 /* Setup L2TP header */ 1207 session->build_header(session, __skb_push(skb, hdr_len)); 1208 1209 /* Reset skb netfilter state */ 1210 memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt)); 1211 IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED | 1212 IPSKB_REROUTED); 1213 nf_reset(skb); 1214 1215 bh_lock_sock(sk); 1216 if (sock_owned_by_user(sk)) { 1217 kfree_skb(skb); 1218 ret = NET_XMIT_DROP; 1219 goto out_unlock; 1220 } 1221 1222 /* Get routing info from the tunnel socket */ 1223 skb_dst_drop(skb); 1224 skb_dst_set(skb, dst_clone(__sk_dst_check(sk, 0))); 1225 1226 inet = inet_sk(sk); 1227 fl = &inet->cork.fl; 1228 switch (tunnel->encap) { 1229 case L2TP_ENCAPTYPE_UDP: 1230 /* Setup UDP header */ 1231 __skb_push(skb, sizeof(*uh)); 1232 skb_reset_transport_header(skb); 1233 uh = udp_hdr(skb); 1234 uh->source = inet->inet_sport; 1235 uh->dest = inet->inet_dport; 1236 udp_len = uhlen + hdr_len + data_len; 1237 uh->len = htons(udp_len); 1238 uh->check = 0; 1239 1240 /* Calculate UDP checksum if configured to do so */ 1241 #if IS_ENABLED(CONFIG_IPV6) 1242 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped) 1243 l2tp_xmit_ipv6_csum(sk, skb, udp_len); 1244 else 1245 #endif 1246 if (sk->sk_no_check == UDP_CSUM_NOXMIT) 1247 skb->ip_summed = CHECKSUM_NONE; 1248 else if ((skb_dst(skb) && skb_dst(skb)->dev) && 1249 (!(skb_dst(skb)->dev->features & NETIF_F_V4_CSUM))) { 1250 skb->ip_summed = CHECKSUM_COMPLETE; 1251 csum = skb_checksum(skb, 0, udp_len, 0); 1252 uh->check = csum_tcpudp_magic(inet->inet_saddr, 1253 inet->inet_daddr, 1254 udp_len, IPPROTO_UDP, csum); 1255 if (uh->check == 0) 1256 uh->check = CSUM_MANGLED_0; 1257 } else { 1258 skb->ip_summed = CHECKSUM_PARTIAL; 1259 skb->csum_start = skb_transport_header(skb) - skb->head; 1260 skb->csum_offset = offsetof(struct udphdr, check); 1261 uh->check = ~csum_tcpudp_magic(inet->inet_saddr, 1262 inet->inet_daddr, 1263 udp_len, IPPROTO_UDP, 0); 1264 } 1265 break; 1266 1267 case L2TP_ENCAPTYPE_IP: 1268 break; 1269 } 1270 1271 l2tp_xmit_core(session, skb, fl, data_len); 1272 out_unlock: 1273 bh_unlock_sock(sk); 1274 1275 return ret; 1276 } 1277 EXPORT_SYMBOL_GPL(l2tp_xmit_skb); 1278 1279 /***************************************************************************** 1280 * Tinnel and session create/destroy. 1281 *****************************************************************************/ 1282 1283 /* Tunnel socket destruct hook. 1284 * The tunnel context is deleted only when all session sockets have been 1285 * closed. 1286 */ 1287 static void l2tp_tunnel_destruct(struct sock *sk) 1288 { 1289 struct l2tp_tunnel *tunnel = l2tp_tunnel(sk); 1290 struct l2tp_net *pn; 1291 1292 if (tunnel == NULL) 1293 goto end; 1294 1295 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name); 1296 1297 1298 /* Disable udp encapsulation */ 1299 switch (tunnel->encap) { 1300 case L2TP_ENCAPTYPE_UDP: 1301 /* No longer an encapsulation socket. See net/ipv4/udp.c */ 1302 (udp_sk(sk))->encap_type = 0; 1303 (udp_sk(sk))->encap_rcv = NULL; 1304 (udp_sk(sk))->encap_destroy = NULL; 1305 break; 1306 case L2TP_ENCAPTYPE_IP: 1307 break; 1308 } 1309 1310 /* Remove hooks into tunnel socket */ 1311 sk->sk_destruct = tunnel->old_sk_destruct; 1312 sk->sk_user_data = NULL; 1313 tunnel->sock = NULL; 1314 1315 /* Remove the tunnel struct from the tunnel list */ 1316 pn = l2tp_pernet(tunnel->l2tp_net); 1317 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1318 list_del_rcu(&tunnel->list); 1319 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1320 atomic_dec(&l2tp_tunnel_count); 1321 1322 l2tp_tunnel_closeall(tunnel); 1323 l2tp_tunnel_dec_refcount(tunnel); 1324 1325 /* Call the original destructor */ 1326 if (sk->sk_destruct) 1327 (*sk->sk_destruct)(sk); 1328 end: 1329 return; 1330 } 1331 1332 /* When the tunnel is closed, all the attached sessions need to go too. 1333 */ 1334 void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel) 1335 { 1336 int hash; 1337 struct hlist_node *walk; 1338 struct hlist_node *tmp; 1339 struct l2tp_session *session; 1340 1341 BUG_ON(tunnel == NULL); 1342 1343 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n", 1344 tunnel->name); 1345 1346 write_lock_bh(&tunnel->hlist_lock); 1347 for (hash = 0; hash < L2TP_HASH_SIZE; hash++) { 1348 again: 1349 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) { 1350 session = hlist_entry(walk, struct l2tp_session, hlist); 1351 1352 l2tp_info(session, L2TP_MSG_CONTROL, 1353 "%s: closing session\n", session->name); 1354 1355 hlist_del_init(&session->hlist); 1356 1357 if (session->ref != NULL) 1358 (*session->ref)(session); 1359 1360 write_unlock_bh(&tunnel->hlist_lock); 1361 1362 __l2tp_session_unhash(session); 1363 l2tp_session_queue_purge(session); 1364 1365 if (session->session_close != NULL) 1366 (*session->session_close)(session); 1367 1368 if (session->deref != NULL) 1369 (*session->deref)(session); 1370 1371 l2tp_session_dec_refcount(session); 1372 1373 write_lock_bh(&tunnel->hlist_lock); 1374 1375 /* Now restart from the beginning of this hash 1376 * chain. We always remove a session from the 1377 * list so we are guaranteed to make forward 1378 * progress. 1379 */ 1380 goto again; 1381 } 1382 } 1383 write_unlock_bh(&tunnel->hlist_lock); 1384 } 1385 EXPORT_SYMBOL_GPL(l2tp_tunnel_closeall); 1386 1387 /* Tunnel socket destroy hook for UDP encapsulation */ 1388 static void l2tp_udp_encap_destroy(struct sock *sk) 1389 { 1390 struct l2tp_tunnel *tunnel = l2tp_sock_to_tunnel(sk); 1391 if (tunnel) { 1392 l2tp_tunnel_closeall(tunnel); 1393 sock_put(sk); 1394 } 1395 } 1396 1397 /* Really kill the tunnel. 1398 * Come here only when all sessions have been cleared from the tunnel. 1399 */ 1400 static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel) 1401 { 1402 BUG_ON(atomic_read(&tunnel->ref_count) != 0); 1403 BUG_ON(tunnel->sock != NULL); 1404 l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name); 1405 kfree_rcu(tunnel, rcu); 1406 } 1407 1408 /* Workqueue tunnel deletion function */ 1409 static void l2tp_tunnel_del_work(struct work_struct *work) 1410 { 1411 struct l2tp_tunnel *tunnel = NULL; 1412 struct socket *sock = NULL; 1413 struct sock *sk = NULL; 1414 1415 tunnel = container_of(work, struct l2tp_tunnel, del_work); 1416 sk = l2tp_tunnel_sock_lookup(tunnel); 1417 if (!sk) 1418 return; 1419 1420 sock = sk->sk_socket; 1421 1422 /* If the tunnel socket was created by userspace, then go through the 1423 * inet layer to shut the socket down, and let userspace close it. 1424 * Otherwise, if we created the socket directly within the kernel, use 1425 * the sk API to release it here. 1426 * In either case the tunnel resources are freed in the socket 1427 * destructor when the tunnel socket goes away. 1428 */ 1429 if (tunnel->fd >= 0) { 1430 if (sock) 1431 inet_shutdown(sock, 2); 1432 } else { 1433 if (sock) 1434 kernel_sock_shutdown(sock, SHUT_RDWR); 1435 sk_release_kernel(sk); 1436 } 1437 1438 l2tp_tunnel_sock_put(sk); 1439 } 1440 1441 /* Create a socket for the tunnel, if one isn't set up by 1442 * userspace. This is used for static tunnels where there is no 1443 * managing L2TP daemon. 1444 * 1445 * Since we don't want these sockets to keep a namespace alive by 1446 * themselves, we drop the socket's namespace refcount after creation. 1447 * These sockets are freed when the namespace exits using the pernet 1448 * exit hook. 1449 */ 1450 static int l2tp_tunnel_sock_create(struct net *net, 1451 u32 tunnel_id, 1452 u32 peer_tunnel_id, 1453 struct l2tp_tunnel_cfg *cfg, 1454 struct socket **sockp) 1455 { 1456 int err = -EINVAL; 1457 struct socket *sock = NULL; 1458 struct sockaddr_in udp_addr = {0}; 1459 struct sockaddr_l2tpip ip_addr = {0}; 1460 #if IS_ENABLED(CONFIG_IPV6) 1461 struct sockaddr_in6 udp6_addr = {0}; 1462 struct sockaddr_l2tpip6 ip6_addr = {0}; 1463 #endif 1464 1465 switch (cfg->encap) { 1466 case L2TP_ENCAPTYPE_UDP: 1467 #if IS_ENABLED(CONFIG_IPV6) 1468 if (cfg->local_ip6 && cfg->peer_ip6) { 1469 err = sock_create_kern(AF_INET6, SOCK_DGRAM, 0, &sock); 1470 if (err < 0) 1471 goto out; 1472 1473 sk_change_net(sock->sk, net); 1474 1475 udp6_addr.sin6_family = AF_INET6; 1476 memcpy(&udp6_addr.sin6_addr, cfg->local_ip6, 1477 sizeof(udp6_addr.sin6_addr)); 1478 udp6_addr.sin6_port = htons(cfg->local_udp_port); 1479 err = kernel_bind(sock, (struct sockaddr *) &udp6_addr, 1480 sizeof(udp6_addr)); 1481 if (err < 0) 1482 goto out; 1483 1484 udp6_addr.sin6_family = AF_INET6; 1485 memcpy(&udp6_addr.sin6_addr, cfg->peer_ip6, 1486 sizeof(udp6_addr.sin6_addr)); 1487 udp6_addr.sin6_port = htons(cfg->peer_udp_port); 1488 err = kernel_connect(sock, 1489 (struct sockaddr *) &udp6_addr, 1490 sizeof(udp6_addr), 0); 1491 if (err < 0) 1492 goto out; 1493 } else 1494 #endif 1495 { 1496 err = sock_create_kern(AF_INET, SOCK_DGRAM, 0, &sock); 1497 if (err < 0) 1498 goto out; 1499 1500 sk_change_net(sock->sk, net); 1501 1502 udp_addr.sin_family = AF_INET; 1503 udp_addr.sin_addr = cfg->local_ip; 1504 udp_addr.sin_port = htons(cfg->local_udp_port); 1505 err = kernel_bind(sock, (struct sockaddr *) &udp_addr, 1506 sizeof(udp_addr)); 1507 if (err < 0) 1508 goto out; 1509 1510 udp_addr.sin_family = AF_INET; 1511 udp_addr.sin_addr = cfg->peer_ip; 1512 udp_addr.sin_port = htons(cfg->peer_udp_port); 1513 err = kernel_connect(sock, 1514 (struct sockaddr *) &udp_addr, 1515 sizeof(udp_addr), 0); 1516 if (err < 0) 1517 goto out; 1518 } 1519 1520 if (!cfg->use_udp_checksums) 1521 sock->sk->sk_no_check = UDP_CSUM_NOXMIT; 1522 1523 break; 1524 1525 case L2TP_ENCAPTYPE_IP: 1526 #if IS_ENABLED(CONFIG_IPV6) 1527 if (cfg->local_ip6 && cfg->peer_ip6) { 1528 err = sock_create_kern(AF_INET6, SOCK_DGRAM, 1529 IPPROTO_L2TP, &sock); 1530 if (err < 0) 1531 goto out; 1532 1533 sk_change_net(sock->sk, net); 1534 1535 ip6_addr.l2tp_family = AF_INET6; 1536 memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6, 1537 sizeof(ip6_addr.l2tp_addr)); 1538 ip6_addr.l2tp_conn_id = tunnel_id; 1539 err = kernel_bind(sock, (struct sockaddr *) &ip6_addr, 1540 sizeof(ip6_addr)); 1541 if (err < 0) 1542 goto out; 1543 1544 ip6_addr.l2tp_family = AF_INET6; 1545 memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6, 1546 sizeof(ip6_addr.l2tp_addr)); 1547 ip6_addr.l2tp_conn_id = peer_tunnel_id; 1548 err = kernel_connect(sock, 1549 (struct sockaddr *) &ip6_addr, 1550 sizeof(ip6_addr), 0); 1551 if (err < 0) 1552 goto out; 1553 } else 1554 #endif 1555 { 1556 err = sock_create_kern(AF_INET, SOCK_DGRAM, 1557 IPPROTO_L2TP, &sock); 1558 if (err < 0) 1559 goto out; 1560 1561 sk_change_net(sock->sk, net); 1562 1563 ip_addr.l2tp_family = AF_INET; 1564 ip_addr.l2tp_addr = cfg->local_ip; 1565 ip_addr.l2tp_conn_id = tunnel_id; 1566 err = kernel_bind(sock, (struct sockaddr *) &ip_addr, 1567 sizeof(ip_addr)); 1568 if (err < 0) 1569 goto out; 1570 1571 ip_addr.l2tp_family = AF_INET; 1572 ip_addr.l2tp_addr = cfg->peer_ip; 1573 ip_addr.l2tp_conn_id = peer_tunnel_id; 1574 err = kernel_connect(sock, (struct sockaddr *) &ip_addr, 1575 sizeof(ip_addr), 0); 1576 if (err < 0) 1577 goto out; 1578 } 1579 break; 1580 1581 default: 1582 goto out; 1583 } 1584 1585 out: 1586 *sockp = sock; 1587 if ((err < 0) && sock) { 1588 kernel_sock_shutdown(sock, SHUT_RDWR); 1589 sk_release_kernel(sock->sk); 1590 *sockp = NULL; 1591 } 1592 1593 return err; 1594 } 1595 1596 static struct lock_class_key l2tp_socket_class; 1597 1598 int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32 peer_tunnel_id, struct l2tp_tunnel_cfg *cfg, struct l2tp_tunnel **tunnelp) 1599 { 1600 struct l2tp_tunnel *tunnel = NULL; 1601 int err; 1602 struct socket *sock = NULL; 1603 struct sock *sk = NULL; 1604 struct l2tp_net *pn; 1605 enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP; 1606 1607 /* Get the tunnel socket from the fd, which was opened by 1608 * the userspace L2TP daemon. If not specified, create a 1609 * kernel socket. 1610 */ 1611 if (fd < 0) { 1612 err = l2tp_tunnel_sock_create(net, tunnel_id, peer_tunnel_id, 1613 cfg, &sock); 1614 if (err < 0) 1615 goto err; 1616 } else { 1617 sock = sockfd_lookup(fd, &err); 1618 if (!sock) { 1619 pr_err("tunl %u: sockfd_lookup(fd=%d) returned %d\n", 1620 tunnel_id, fd, err); 1621 err = -EBADF; 1622 goto err; 1623 } 1624 1625 /* Reject namespace mismatches */ 1626 if (!net_eq(sock_net(sock->sk), net)) { 1627 pr_err("tunl %u: netns mismatch\n", tunnel_id); 1628 err = -EINVAL; 1629 goto err; 1630 } 1631 } 1632 1633 sk = sock->sk; 1634 1635 if (cfg != NULL) 1636 encap = cfg->encap; 1637 1638 /* Quick sanity checks */ 1639 switch (encap) { 1640 case L2TP_ENCAPTYPE_UDP: 1641 err = -EPROTONOSUPPORT; 1642 if (sk->sk_protocol != IPPROTO_UDP) { 1643 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n", 1644 tunnel_id, fd, sk->sk_protocol, IPPROTO_UDP); 1645 goto err; 1646 } 1647 break; 1648 case L2TP_ENCAPTYPE_IP: 1649 err = -EPROTONOSUPPORT; 1650 if (sk->sk_protocol != IPPROTO_L2TP) { 1651 pr_err("tunl %hu: fd %d wrong protocol, got %d, expected %d\n", 1652 tunnel_id, fd, sk->sk_protocol, IPPROTO_L2TP); 1653 goto err; 1654 } 1655 break; 1656 } 1657 1658 /* Check if this socket has already been prepped */ 1659 tunnel = l2tp_tunnel(sk); 1660 if (tunnel != NULL) { 1661 /* This socket has already been prepped */ 1662 err = -EBUSY; 1663 goto err; 1664 } 1665 1666 tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL); 1667 if (tunnel == NULL) { 1668 err = -ENOMEM; 1669 goto err; 1670 } 1671 1672 tunnel->version = version; 1673 tunnel->tunnel_id = tunnel_id; 1674 tunnel->peer_tunnel_id = peer_tunnel_id; 1675 tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS; 1676 1677 tunnel->magic = L2TP_TUNNEL_MAGIC; 1678 sprintf(&tunnel->name[0], "tunl %u", tunnel_id); 1679 rwlock_init(&tunnel->hlist_lock); 1680 1681 /* The net we belong to */ 1682 tunnel->l2tp_net = net; 1683 pn = l2tp_pernet(net); 1684 1685 if (cfg != NULL) 1686 tunnel->debug = cfg->debug; 1687 1688 #if IS_ENABLED(CONFIG_IPV6) 1689 if (sk->sk_family == PF_INET6) { 1690 struct ipv6_pinfo *np = inet6_sk(sk); 1691 1692 if (ipv6_addr_v4mapped(&np->saddr) && 1693 ipv6_addr_v4mapped(&sk->sk_v6_daddr)) { 1694 struct inet_sock *inet = inet_sk(sk); 1695 1696 tunnel->v4mapped = true; 1697 inet->inet_saddr = np->saddr.s6_addr32[3]; 1698 inet->inet_rcv_saddr = sk->sk_v6_rcv_saddr.s6_addr32[3]; 1699 inet->inet_daddr = sk->sk_v6_daddr.s6_addr32[3]; 1700 } else { 1701 tunnel->v4mapped = false; 1702 } 1703 } 1704 #endif 1705 1706 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */ 1707 tunnel->encap = encap; 1708 if (encap == L2TP_ENCAPTYPE_UDP) { 1709 /* Mark socket as an encapsulation socket. See net/ipv4/udp.c */ 1710 udp_sk(sk)->encap_type = UDP_ENCAP_L2TPINUDP; 1711 udp_sk(sk)->encap_rcv = l2tp_udp_encap_recv; 1712 udp_sk(sk)->encap_destroy = l2tp_udp_encap_destroy; 1713 #if IS_ENABLED(CONFIG_IPV6) 1714 if (sk->sk_family == PF_INET6 && !tunnel->v4mapped) 1715 udpv6_encap_enable(); 1716 else 1717 #endif 1718 udp_encap_enable(); 1719 } 1720 1721 sk->sk_user_data = tunnel; 1722 1723 /* Hook on the tunnel socket destructor so that we can cleanup 1724 * if the tunnel socket goes away. 1725 */ 1726 tunnel->old_sk_destruct = sk->sk_destruct; 1727 sk->sk_destruct = &l2tp_tunnel_destruct; 1728 tunnel->sock = sk; 1729 tunnel->fd = fd; 1730 lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class, "l2tp_sock"); 1731 1732 sk->sk_allocation = GFP_ATOMIC; 1733 1734 /* Init delete workqueue struct */ 1735 INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work); 1736 1737 /* Add tunnel to our list */ 1738 INIT_LIST_HEAD(&tunnel->list); 1739 atomic_inc(&l2tp_tunnel_count); 1740 1741 /* Bump the reference count. The tunnel context is deleted 1742 * only when this drops to zero. Must be done before list insertion 1743 */ 1744 l2tp_tunnel_inc_refcount(tunnel); 1745 spin_lock_bh(&pn->l2tp_tunnel_list_lock); 1746 list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list); 1747 spin_unlock_bh(&pn->l2tp_tunnel_list_lock); 1748 1749 err = 0; 1750 err: 1751 if (tunnelp) 1752 *tunnelp = tunnel; 1753 1754 /* If tunnel's socket was created by the kernel, it doesn't 1755 * have a file. 1756 */ 1757 if (sock && sock->file) 1758 sockfd_put(sock); 1759 1760 return err; 1761 } 1762 EXPORT_SYMBOL_GPL(l2tp_tunnel_create); 1763 1764 /* This function is used by the netlink TUNNEL_DELETE command. 1765 */ 1766 int l2tp_tunnel_delete(struct l2tp_tunnel *tunnel) 1767 { 1768 l2tp_tunnel_closeall(tunnel); 1769 return (false == queue_work(l2tp_wq, &tunnel->del_work)); 1770 } 1771 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete); 1772 1773 /* Really kill the session. 1774 */ 1775 void l2tp_session_free(struct l2tp_session *session) 1776 { 1777 struct l2tp_tunnel *tunnel = session->tunnel; 1778 1779 BUG_ON(atomic_read(&session->ref_count) != 0); 1780 1781 if (tunnel) { 1782 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC); 1783 if (session->session_id != 0) 1784 atomic_dec(&l2tp_session_count); 1785 sock_put(tunnel->sock); 1786 session->tunnel = NULL; 1787 l2tp_tunnel_dec_refcount(tunnel); 1788 } 1789 1790 kfree(session); 1791 } 1792 EXPORT_SYMBOL_GPL(l2tp_session_free); 1793 1794 /* Remove an l2tp session from l2tp_core's hash lists. 1795 * Provides a tidyup interface for pseudowire code which can't just route all 1796 * shutdown via. l2tp_session_delete and a pseudowire-specific session_close 1797 * callback. 1798 */ 1799 void __l2tp_session_unhash(struct l2tp_session *session) 1800 { 1801 struct l2tp_tunnel *tunnel = session->tunnel; 1802 1803 /* Remove the session from core hashes */ 1804 if (tunnel) { 1805 /* Remove from the per-tunnel hash */ 1806 write_lock_bh(&tunnel->hlist_lock); 1807 hlist_del_init(&session->hlist); 1808 write_unlock_bh(&tunnel->hlist_lock); 1809 1810 /* For L2TPv3 we have a per-net hash: remove from there, too */ 1811 if (tunnel->version != L2TP_HDR_VER_2) { 1812 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1813 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1814 hlist_del_init_rcu(&session->global_hlist); 1815 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1816 synchronize_rcu(); 1817 } 1818 } 1819 } 1820 EXPORT_SYMBOL_GPL(__l2tp_session_unhash); 1821 1822 /* This function is used by the netlink SESSION_DELETE command and by 1823 pseudowire modules. 1824 */ 1825 int l2tp_session_delete(struct l2tp_session *session) 1826 { 1827 if (session->ref) 1828 (*session->ref)(session); 1829 __l2tp_session_unhash(session); 1830 l2tp_session_queue_purge(session); 1831 if (session->session_close != NULL) 1832 (*session->session_close)(session); 1833 if (session->deref) 1834 (*session->deref)(session); 1835 l2tp_session_dec_refcount(session); 1836 return 0; 1837 } 1838 EXPORT_SYMBOL_GPL(l2tp_session_delete); 1839 1840 /* We come here whenever a session's send_seq, cookie_len or 1841 * l2specific_len parameters are set. 1842 */ 1843 void l2tp_session_set_header_len(struct l2tp_session *session, int version) 1844 { 1845 if (version == L2TP_HDR_VER_2) { 1846 session->hdr_len = 6; 1847 if (session->send_seq) 1848 session->hdr_len += 4; 1849 } else { 1850 session->hdr_len = 4 + session->cookie_len + session->l2specific_len + session->offset; 1851 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP) 1852 session->hdr_len += 4; 1853 } 1854 1855 } 1856 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len); 1857 1858 struct l2tp_session *l2tp_session_create(int priv_size, struct l2tp_tunnel *tunnel, u32 session_id, u32 peer_session_id, struct l2tp_session_cfg *cfg) 1859 { 1860 struct l2tp_session *session; 1861 1862 session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL); 1863 if (session != NULL) { 1864 session->magic = L2TP_SESSION_MAGIC; 1865 session->tunnel = tunnel; 1866 1867 session->session_id = session_id; 1868 session->peer_session_id = peer_session_id; 1869 session->nr = 0; 1870 if (tunnel->version == L2TP_HDR_VER_2) 1871 session->nr_max = 0xffff; 1872 else 1873 session->nr_max = 0xffffff; 1874 session->nr_window_size = session->nr_max / 2; 1875 session->nr_oos_count_max = 4; 1876 1877 /* Use NR of first received packet */ 1878 session->reorder_skip = 1; 1879 1880 sprintf(&session->name[0], "sess %u/%u", 1881 tunnel->tunnel_id, session->session_id); 1882 1883 skb_queue_head_init(&session->reorder_q); 1884 1885 INIT_HLIST_NODE(&session->hlist); 1886 INIT_HLIST_NODE(&session->global_hlist); 1887 1888 /* Inherit debug options from tunnel */ 1889 session->debug = tunnel->debug; 1890 1891 if (cfg) { 1892 session->pwtype = cfg->pw_type; 1893 session->debug = cfg->debug; 1894 session->mtu = cfg->mtu; 1895 session->mru = cfg->mru; 1896 session->send_seq = cfg->send_seq; 1897 session->recv_seq = cfg->recv_seq; 1898 session->lns_mode = cfg->lns_mode; 1899 session->reorder_timeout = cfg->reorder_timeout; 1900 session->offset = cfg->offset; 1901 session->l2specific_type = cfg->l2specific_type; 1902 session->l2specific_len = cfg->l2specific_len; 1903 session->cookie_len = cfg->cookie_len; 1904 memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len); 1905 session->peer_cookie_len = cfg->peer_cookie_len; 1906 memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len); 1907 } 1908 1909 if (tunnel->version == L2TP_HDR_VER_2) 1910 session->build_header = l2tp_build_l2tpv2_header; 1911 else 1912 session->build_header = l2tp_build_l2tpv3_header; 1913 1914 l2tp_session_set_header_len(session, tunnel->version); 1915 1916 /* Bump the reference count. The session context is deleted 1917 * only when this drops to zero. 1918 */ 1919 l2tp_session_inc_refcount(session); 1920 l2tp_tunnel_inc_refcount(tunnel); 1921 1922 /* Ensure tunnel socket isn't deleted */ 1923 sock_hold(tunnel->sock); 1924 1925 /* Add session to the tunnel's hash list */ 1926 write_lock_bh(&tunnel->hlist_lock); 1927 hlist_add_head(&session->hlist, 1928 l2tp_session_id_hash(tunnel, session_id)); 1929 write_unlock_bh(&tunnel->hlist_lock); 1930 1931 /* And to the global session list if L2TPv3 */ 1932 if (tunnel->version != L2TP_HDR_VER_2) { 1933 struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net); 1934 1935 spin_lock_bh(&pn->l2tp_session_hlist_lock); 1936 hlist_add_head_rcu(&session->global_hlist, 1937 l2tp_session_id_hash_2(pn, session_id)); 1938 spin_unlock_bh(&pn->l2tp_session_hlist_lock); 1939 } 1940 1941 /* Ignore management session in session count value */ 1942 if (session->session_id != 0) 1943 atomic_inc(&l2tp_session_count); 1944 } 1945 1946 return session; 1947 } 1948 EXPORT_SYMBOL_GPL(l2tp_session_create); 1949 1950 /***************************************************************************** 1951 * Init and cleanup 1952 *****************************************************************************/ 1953 1954 static __net_init int l2tp_init_net(struct net *net) 1955 { 1956 struct l2tp_net *pn = net_generic(net, l2tp_net_id); 1957 int hash; 1958 1959 INIT_LIST_HEAD(&pn->l2tp_tunnel_list); 1960 spin_lock_init(&pn->l2tp_tunnel_list_lock); 1961 1962 for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) 1963 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]); 1964 1965 spin_lock_init(&pn->l2tp_session_hlist_lock); 1966 1967 return 0; 1968 } 1969 1970 static __net_exit void l2tp_exit_net(struct net *net) 1971 { 1972 struct l2tp_net *pn = l2tp_pernet(net); 1973 struct l2tp_tunnel *tunnel = NULL; 1974 1975 rcu_read_lock_bh(); 1976 list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) { 1977 (void)l2tp_tunnel_delete(tunnel); 1978 } 1979 rcu_read_unlock_bh(); 1980 } 1981 1982 static struct pernet_operations l2tp_net_ops = { 1983 .init = l2tp_init_net, 1984 .exit = l2tp_exit_net, 1985 .id = &l2tp_net_id, 1986 .size = sizeof(struct l2tp_net), 1987 }; 1988 1989 static int __init l2tp_init(void) 1990 { 1991 int rc = 0; 1992 1993 rc = register_pernet_device(&l2tp_net_ops); 1994 if (rc) 1995 goto out; 1996 1997 l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0); 1998 if (!l2tp_wq) { 1999 pr_err("alloc_workqueue failed\n"); 2000 rc = -ENOMEM; 2001 goto out; 2002 } 2003 2004 pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION); 2005 2006 out: 2007 return rc; 2008 } 2009 2010 static void __exit l2tp_exit(void) 2011 { 2012 unregister_pernet_device(&l2tp_net_ops); 2013 if (l2tp_wq) { 2014 destroy_workqueue(l2tp_wq); 2015 l2tp_wq = NULL; 2016 } 2017 } 2018 2019 module_init(l2tp_init); 2020 module_exit(l2tp_exit); 2021 2022 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>"); 2023 MODULE_DESCRIPTION("L2TP core"); 2024 MODULE_LICENSE("GPL"); 2025 MODULE_VERSION(L2TP_DRV_VERSION); 2026 2027