net/l2tp/l2tp

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This source file includes following definitions.
l2tp_sk_is_v6
l2tp_pernet
l2tp_session_id_hash_2
l2tp_session_id_hash
l2tp_tunnel_free
l2tp_tunnel_get
l2tp_tunnel_get_nth
l2tp_tunnel_get_session
l2tp_session_get
l2tp_session_get_nth
l2tp_session_get_by_ifname
l2tp_session_register
l2tp_recv_queue_skb
l2tp_recv_dequeue_skb
l2tp_recv_dequeue
l2tp_seq_check_rx_window
l2tp_recv_data_seq
l2tp_recv_common
l2tp_session_queue_purge
l2tp_udp_recv_core
l2tp_udp_encap_recv
l2tp_build_l2tpv2_header
l2tp_build_l2tpv3_header
l2tp_xmit_core
l2tp_xmit_skb
l2tp_tunnel_destruct
l2tp_tunnel_closeall
l2tp_udp_encap_destroy
l2tp_tunnel_del_work
l2tp_tunnel_sock_create
l2tp_tunnel_create
l2tp_validate_socket
l2tp_tunnel_register
l2tp_tunnel_delete
l2tp_session_free
__l2tp_session_unhash
l2tp_session_delete
l2tp_session_set_header_len
l2tp_session_create
l2tp_init_net
l2tp_exit_net
l2tp_init
l2tp_exit
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * L2TP core.
   4  *
   5  * Copyright (c) 2008,2009,2010 Katalix Systems Ltd
   6  *
   7  * This file contains some code of the original L2TPv2 pppol2tp
   8  * driver, which has the following copyright:
   9  *
  10  * Authors:     Martijn van Oosterhout <kleptog@svana.org>
  11  *              James Chapman (jchapman@katalix.com)
  12  * Contributors:
  13  *              Michal Ostrowski <mostrows@speakeasy.net>
  14  *              Arnaldo Carvalho de Melo <acme@xconectiva.com.br>
  15  *              David S. Miller (davem@redhat.com)
  16  */
  17 
  18 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  19 
  20 #include <linux/module.h>
  21 #include <linux/string.h>
  22 #include <linux/list.h>
  23 #include <linux/rculist.h>
  24 #include <linux/uaccess.h>
  25 
  26 #include <linux/kernel.h>
  27 #include <linux/spinlock.h>
  28 #include <linux/kthread.h>
  29 #include <linux/sched.h>
  30 #include <linux/slab.h>
  31 #include <linux/errno.h>
  32 #include <linux/jiffies.h>
  33 
  34 #include <linux/netdevice.h>
  35 #include <linux/net.h>
  36 #include <linux/inetdevice.h>
  37 #include <linux/skbuff.h>
  38 #include <linux/init.h>
  39 #include <linux/in.h>
  40 #include <linux/ip.h>
  41 #include <linux/udp.h>
  42 #include <linux/l2tp.h>
  43 #include <linux/hash.h>
  44 #include <linux/sort.h>
  45 #include <linux/file.h>
  46 #include <linux/nsproxy.h>
  47 #include <net/net_namespace.h>
  48 #include <net/netns/generic.h>
  49 #include <net/dst.h>
  50 #include <net/ip.h>
  51 #include <net/udp.h>
  52 #include <net/udp_tunnel.h>
  53 #include <net/inet_common.h>
  54 #include <net/xfrm.h>
  55 #include <net/protocol.h>
  56 #include <net/inet6_connection_sock.h>
  57 #include <net/inet_ecn.h>
  58 #include <net/ip6_route.h>
  59 #include <net/ip6_checksum.h>
  60 
  61 #include <asm/byteorder.h>
  62 #include <linux/atomic.h>
  63 
  64 #include "l2tp_core.h"
  65 
  66 #define L2TP_DRV_VERSION        "V2.0"
  67 
  68 /* L2TP header constants */
  69 #define L2TP_HDRFLAG_T     0x8000
  70 #define L2TP_HDRFLAG_L     0x4000
  71 #define L2TP_HDRFLAG_S     0x0800
  72 #define L2TP_HDRFLAG_O     0x0200
  73 #define L2TP_HDRFLAG_P     0x0100
  74 
  75 #define L2TP_HDR_VER_MASK  0x000F
  76 #define L2TP_HDR_VER_2     0x0002
  77 #define L2TP_HDR_VER_3     0x0003
  78 
  79 /* L2TPv3 default L2-specific sublayer */
  80 #define L2TP_SLFLAG_S      0x40000000
  81 #define L2TP_SL_SEQ_MASK   0x00ffffff
  82 
  83 #define L2TP_HDR_SIZE_MAX               14
  84 
  85 /* Default trace flags */
  86 #define L2TP_DEFAULT_DEBUG_FLAGS        0
  87 
  88 /* Private data stored for received packets in the skb.
  89  */
  90 struct l2tp_skb_cb {
  91         u32                     ns;
  92         u16                     has_seq;
  93         u16                     length;
  94         unsigned long           expires;
  95 };
  96 
  97 #define L2TP_SKB_CB(skb)        ((struct l2tp_skb_cb *) &skb->cb[sizeof(struct inet_skb_parm)])
  98 
  99 static struct workqueue_struct *l2tp_wq;
 100 
 101 /* per-net private data for this module */
 102 static unsigned int l2tp_net_id;
 103 struct l2tp_net {
 104         struct list_head l2tp_tunnel_list;
 105         spinlock_t l2tp_tunnel_list_lock;
 106         struct hlist_head l2tp_session_hlist[L2TP_HASH_SIZE_2];
 107         spinlock_t l2tp_session_hlist_lock;
 108 };
 109 
 110 #if IS_ENABLED(CONFIG_IPV6)
 111 static bool l2tp_sk_is_v6(struct sock *sk)
 112 {
 113         return sk->sk_family == PF_INET6 &&
 114                !ipv6_addr_v4mapped(&sk->sk_v6_daddr);
 115 }
 116 #endif
 117 
 118 static inline struct l2tp_tunnel *l2tp_tunnel(struct sock *sk)
 119 {
 120         return sk->sk_user_data;
 121 }
 122 
 123 static inline struct l2tp_net *l2tp_pernet(const struct net *net)
 124 {
 125         BUG_ON(!net);
 126 
 127         return net_generic(net, l2tp_net_id);
 128 }
 129 
 130 /* Session hash global list for L2TPv3.
 131  * The session_id SHOULD be random according to RFC3931, but several
 132  * L2TP implementations use incrementing session_ids.  So we do a real
 133  * hash on the session_id, rather than a simple bitmask.
 134  */
 135 static inline struct hlist_head *
 136 l2tp_session_id_hash_2(struct l2tp_net *pn, u32 session_id)
 137 {
 138         return &pn->l2tp_session_hlist[hash_32(session_id, L2TP_HASH_BITS_2)];
 139 
 140 }
 141 
 142 /* Session hash list.
 143  * The session_id SHOULD be random according to RFC2661, but several
 144  * L2TP implementations (Cisco and Microsoft) use incrementing
 145  * session_ids.  So we do a real hash on the session_id, rather than a
 146  * simple bitmask.
 147  */
 148 static inline struct hlist_head *
 149 l2tp_session_id_hash(struct l2tp_tunnel *tunnel, u32 session_id)
 150 {
 151         return &tunnel->session_hlist[hash_32(session_id, L2TP_HASH_BITS)];
 152 }
 153 
 154 void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
 155 {
 156         sock_put(tunnel->sock);
 157         /* the tunnel is freed in the socket destructor */
 158 }
 159 EXPORT_SYMBOL(l2tp_tunnel_free);
 160 
 161 /* Lookup a tunnel. A new reference is held on the returned tunnel. */
 162 struct l2tp_tunnel *l2tp_tunnel_get(const struct net *net, u32 tunnel_id)
 163 {
 164         const struct l2tp_net *pn = l2tp_pernet(net);
 165         struct l2tp_tunnel *tunnel;
 166 
 167         rcu_read_lock_bh();
 168         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 169                 if (tunnel->tunnel_id == tunnel_id &&
 170                     refcount_inc_not_zero(&tunnel->ref_count)) {
 171                         rcu_read_unlock_bh();
 172 
 173                         return tunnel;
 174                 }
 175         }
 176         rcu_read_unlock_bh();
 177 
 178         return NULL;
 179 }
 180 EXPORT_SYMBOL_GPL(l2tp_tunnel_get);
 181 
 182 struct l2tp_tunnel *l2tp_tunnel_get_nth(const struct net *net, int nth)
 183 {
 184         const struct l2tp_net *pn = l2tp_pernet(net);
 185         struct l2tp_tunnel *tunnel;
 186         int count = 0;
 187 
 188         rcu_read_lock_bh();
 189         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
 190                 if (++count > nth &&
 191                     refcount_inc_not_zero(&tunnel->ref_count)) {
 192                         rcu_read_unlock_bh();
 193                         return tunnel;
 194                 }
 195         }
 196         rcu_read_unlock_bh();
 197 
 198         return NULL;
 199 }
 200 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_nth);
 201 
 202 struct l2tp_session *l2tp_tunnel_get_session(struct l2tp_tunnel *tunnel,
 203                                              u32 session_id)
 204 {
 205         struct hlist_head *session_list;
 206         struct l2tp_session *session;
 207 
 208         session_list = l2tp_session_id_hash(tunnel, session_id);
 209 
 210         read_lock_bh(&tunnel->hlist_lock);
 211         hlist_for_each_entry(session, session_list, hlist)
 212                 if (session->session_id == session_id) {
 213                         l2tp_session_inc_refcount(session);
 214                         read_unlock_bh(&tunnel->hlist_lock);
 215 
 216                         return session;
 217                 }
 218         read_unlock_bh(&tunnel->hlist_lock);
 219 
 220         return NULL;
 221 }
 222 EXPORT_SYMBOL_GPL(l2tp_tunnel_get_session);
 223 
 224 struct l2tp_session *l2tp_session_get(const struct net *net, u32 session_id)
 225 {
 226         struct hlist_head *session_list;
 227         struct l2tp_session *session;
 228 
 229         session_list = l2tp_session_id_hash_2(l2tp_pernet(net), session_id);
 230 
 231         rcu_read_lock_bh();
 232         hlist_for_each_entry_rcu(session, session_list, global_hlist)
 233                 if (session->session_id == session_id) {
 234                         l2tp_session_inc_refcount(session);
 235                         rcu_read_unlock_bh();
 236 
 237                         return session;
 238                 }
 239         rcu_read_unlock_bh();
 240 
 241         return NULL;
 242 }
 243 EXPORT_SYMBOL_GPL(l2tp_session_get);
 244 
 245 struct l2tp_session *l2tp_session_get_nth(struct l2tp_tunnel *tunnel, int nth)
 246 {
 247         int hash;
 248         struct l2tp_session *session;
 249         int count = 0;
 250 
 251         read_lock_bh(&tunnel->hlist_lock);
 252         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
 253                 hlist_for_each_entry(session, &tunnel->session_hlist[hash], hlist) {
 254                         if (++count > nth) {
 255                                 l2tp_session_inc_refcount(session);
 256                                 read_unlock_bh(&tunnel->hlist_lock);
 257                                 return session;
 258                         }
 259                 }
 260         }
 261 
 262         read_unlock_bh(&tunnel->hlist_lock);
 263 
 264         return NULL;
 265 }
 266 EXPORT_SYMBOL_GPL(l2tp_session_get_nth);
 267 
 268 /* Lookup a session by interface name.
 269  * This is very inefficient but is only used by management interfaces.
 270  */
 271 struct l2tp_session *l2tp_session_get_by_ifname(const struct net *net,
 272                                                 const char *ifname)
 273 {
 274         struct l2tp_net *pn = l2tp_pernet(net);
 275         int hash;
 276         struct l2tp_session *session;
 277 
 278         rcu_read_lock_bh();
 279         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++) {
 280                 hlist_for_each_entry_rcu(session, &pn->l2tp_session_hlist[hash], global_hlist) {
 281                         if (!strcmp(session->ifname, ifname)) {
 282                                 l2tp_session_inc_refcount(session);
 283                                 rcu_read_unlock_bh();
 284 
 285                                 return session;
 286                         }
 287                 }
 288         }
 289 
 290         rcu_read_unlock_bh();
 291 
 292         return NULL;
 293 }
 294 EXPORT_SYMBOL_GPL(l2tp_session_get_by_ifname);
 295 
 296 int l2tp_session_register(struct l2tp_session *session,
 297                           struct l2tp_tunnel *tunnel)
 298 {
 299         struct l2tp_session *session_walk;
 300         struct hlist_head *g_head;
 301         struct hlist_head *head;
 302         struct l2tp_net *pn;
 303         int err;
 304 
 305         head = l2tp_session_id_hash(tunnel, session->session_id);
 306 
 307         write_lock_bh(&tunnel->hlist_lock);
 308         if (!tunnel->acpt_newsess) {
 309                 err = -ENODEV;
 310                 goto err_tlock;
 311         }
 312 
 313         hlist_for_each_entry(session_walk, head, hlist)
 314                 if (session_walk->session_id == session->session_id) {
 315                         err = -EEXIST;
 316                         goto err_tlock;
 317                 }
 318 
 319         if (tunnel->version == L2TP_HDR_VER_3) {
 320                 pn = l2tp_pernet(tunnel->l2tp_net);
 321                 g_head = l2tp_session_id_hash_2(pn, session->session_id);
 322 
 323                 spin_lock_bh(&pn->l2tp_session_hlist_lock);
 324 
 325                 /* IP encap expects session IDs to be globally unique, while
 326                  * UDP encap doesn't.
 327                  */
 328                 hlist_for_each_entry(session_walk, g_head, global_hlist)
 329                         if (session_walk->session_id == session->session_id &&
 330                             (session_walk->tunnel->encap == L2TP_ENCAPTYPE_IP ||
 331                              tunnel->encap == L2TP_ENCAPTYPE_IP)) {
 332                                 err = -EEXIST;
 333                                 goto err_tlock_pnlock;
 334                         }
 335 
 336                 l2tp_tunnel_inc_refcount(tunnel);
 337                 hlist_add_head_rcu(&session->global_hlist, g_head);
 338 
 339                 spin_unlock_bh(&pn->l2tp_session_hlist_lock);
 340         } else {
 341                 l2tp_tunnel_inc_refcount(tunnel);
 342         }
 343 
 344         hlist_add_head(&session->hlist, head);
 345         write_unlock_bh(&tunnel->hlist_lock);
 346 
 347         return 0;
 348 
 349 err_tlock_pnlock:
 350         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
 351 err_tlock:
 352         write_unlock_bh(&tunnel->hlist_lock);
 353 
 354         return err;
 355 }
 356 EXPORT_SYMBOL_GPL(l2tp_session_register);
 357 
 358 /*****************************************************************************
 359  * Receive data handling
 360  *****************************************************************************/
 361 
 362 /* Queue a skb in order. We come here only if the skb has an L2TP sequence
 363  * number.
 364  */
 365 static void l2tp_recv_queue_skb(struct l2tp_session *session, struct sk_buff *skb)
 366 {
 367         struct sk_buff *skbp;
 368         struct sk_buff *tmp;
 369         u32 ns = L2TP_SKB_CB(skb)->ns;
 370 
 371         spin_lock_bh(&session->reorder_q.lock);
 372         skb_queue_walk_safe(&session->reorder_q, skbp, tmp) {
 373                 if (L2TP_SKB_CB(skbp)->ns > ns) {
 374                         __skb_queue_before(&session->reorder_q, skbp, skb);
 375                         l2tp_dbg(session, L2TP_MSG_SEQ,
 376                                  "%s: pkt %hu, inserted before %hu, reorder_q len=%d\n",
 377                                  session->name, ns, L2TP_SKB_CB(skbp)->ns,
 378                                  skb_queue_len(&session->reorder_q));
 379                         atomic_long_inc(&session->stats.rx_oos_packets);
 380                         goto out;
 381                 }
 382         }
 383 
 384         __skb_queue_tail(&session->reorder_q, skb);
 385 
 386 out:
 387         spin_unlock_bh(&session->reorder_q.lock);
 388 }
 389 
 390 /* Dequeue a single skb.
 391  */
 392 static void l2tp_recv_dequeue_skb(struct l2tp_session *session, struct sk_buff *skb)
 393 {
 394         struct l2tp_tunnel *tunnel = session->tunnel;
 395         int length = L2TP_SKB_CB(skb)->length;
 396 
 397         /* We're about to requeue the skb, so return resources
 398          * to its current owner (a socket receive buffer).
 399          */
 400         skb_orphan(skb);
 401 
 402         atomic_long_inc(&tunnel->stats.rx_packets);
 403         atomic_long_add(length, &tunnel->stats.rx_bytes);
 404         atomic_long_inc(&session->stats.rx_packets);
 405         atomic_long_add(length, &session->stats.rx_bytes);
 406 
 407         if (L2TP_SKB_CB(skb)->has_seq) {
 408                 /* Bump our Nr */
 409                 session->nr++;
 410                 session->nr &= session->nr_max;
 411 
 412                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated nr to %hu\n",
 413                          session->name, session->nr);
 414         }
 415 
 416         /* call private receive handler */
 417         if (session->recv_skb != NULL)
 418                 (*session->recv_skb)(session, skb, L2TP_SKB_CB(skb)->length);
 419         else
 420                 kfree_skb(skb);
 421 }
 422 
 423 /* Dequeue skbs from the session's reorder_q, subject to packet order.
 424  * Skbs that have been in the queue for too long are simply discarded.
 425  */
 426 static void l2tp_recv_dequeue(struct l2tp_session *session)
 427 {
 428         struct sk_buff *skb;
 429         struct sk_buff *tmp;
 430 
 431         /* If the pkt at the head of the queue has the nr that we
 432          * expect to send up next, dequeue it and any other
 433          * in-sequence packets behind it.
 434          */
 435 start:
 436         spin_lock_bh(&session->reorder_q.lock);
 437         skb_queue_walk_safe(&session->reorder_q, skb, tmp) {
 438                 if (time_after(jiffies, L2TP_SKB_CB(skb)->expires)) {
 439                         atomic_long_inc(&session->stats.rx_seq_discards);
 440                         atomic_long_inc(&session->stats.rx_errors);
 441                         l2tp_dbg(session, L2TP_MSG_SEQ,
 442                                  "%s: oos pkt %u len %d discarded (too old), waiting for %u, reorder_q_len=%d\n",
 443                                  session->name, L2TP_SKB_CB(skb)->ns,
 444                                  L2TP_SKB_CB(skb)->length, session->nr,
 445                                  skb_queue_len(&session->reorder_q));
 446                         session->reorder_skip = 1;
 447                         __skb_unlink(skb, &session->reorder_q);
 448                         kfree_skb(skb);
 449                         continue;
 450                 }
 451 
 452                 if (L2TP_SKB_CB(skb)->has_seq) {
 453                         if (session->reorder_skip) {
 454                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 455                                          "%s: advancing nr to next pkt: %u -> %u",
 456                                          session->name, session->nr,
 457                                          L2TP_SKB_CB(skb)->ns);
 458                                 session->reorder_skip = 0;
 459                                 session->nr = L2TP_SKB_CB(skb)->ns;
 460                         }
 461                         if (L2TP_SKB_CB(skb)->ns != session->nr) {
 462                                 l2tp_dbg(session, L2TP_MSG_SEQ,
 463                                          "%s: holding oos pkt %u len %d, waiting for %u, reorder_q_len=%d\n",
 464                                          session->name, L2TP_SKB_CB(skb)->ns,
 465                                          L2TP_SKB_CB(skb)->length, session->nr,
 466                                          skb_queue_len(&session->reorder_q));
 467                                 goto out;
 468                         }
 469                 }
 470                 __skb_unlink(skb, &session->reorder_q);
 471 
 472                 /* Process the skb. We release the queue lock while we
 473                  * do so to let other contexts process the queue.
 474                  */
 475                 spin_unlock_bh(&session->reorder_q.lock);
 476                 l2tp_recv_dequeue_skb(session, skb);
 477                 goto start;
 478         }
 479 
 480 out:
 481         spin_unlock_bh(&session->reorder_q.lock);
 482 }
 483 
 484 static int l2tp_seq_check_rx_window(struct l2tp_session *session, u32 nr)
 485 {
 486         u32 nws;
 487 
 488         if (nr >= session->nr)
 489                 nws = nr - session->nr;
 490         else
 491                 nws = (session->nr_max + 1) - (session->nr - nr);
 492 
 493         return nws < session->nr_window_size;
 494 }
 495 
 496 /* If packet has sequence numbers, queue it if acceptable. Returns 0 if
 497  * acceptable, else non-zero.
 498  */
 499 static int l2tp_recv_data_seq(struct l2tp_session *session, struct sk_buff *skb)
 500 {
 501         if (!l2tp_seq_check_rx_window(session, L2TP_SKB_CB(skb)->ns)) {
 502                 /* Packet sequence number is outside allowed window.
 503                  * Discard it.
 504                  */
 505                 l2tp_dbg(session, L2TP_MSG_SEQ,
 506                          "%s: pkt %u len %d discarded, outside window, nr=%u\n",
 507                          session->name, L2TP_SKB_CB(skb)->ns,
 508                          L2TP_SKB_CB(skb)->length, session->nr);
 509                 goto discard;
 510         }
 511 
 512         if (session->reorder_timeout != 0) {
 513                 /* Packet reordering enabled. Add skb to session's
 514                  * reorder queue, in order of ns.
 515                  */
 516                 l2tp_recv_queue_skb(session, skb);
 517                 goto out;
 518         }
 519 
 520         /* Packet reordering disabled. Discard out-of-sequence packets, while
 521          * tracking the number if in-sequence packets after the first OOS packet
 522          * is seen. After nr_oos_count_max in-sequence packets, reset the
 523          * sequence number to re-enable packet reception.
 524          */
 525         if (L2TP_SKB_CB(skb)->ns == session->nr) {
 526                 skb_queue_tail(&session->reorder_q, skb);
 527         } else {
 528                 u32 nr_oos = L2TP_SKB_CB(skb)->ns;
 529                 u32 nr_next = (session->nr_oos + 1) & session->nr_max;
 530 
 531                 if (nr_oos == nr_next)
 532                         session->nr_oos_count++;
 533                 else
 534                         session->nr_oos_count = 0;
 535 
 536                 session->nr_oos = nr_oos;
 537                 if (session->nr_oos_count > session->nr_oos_count_max) {
 538                         session->reorder_skip = 1;
 539                         l2tp_dbg(session, L2TP_MSG_SEQ,
 540                                  "%s: %d oos packets received. Resetting sequence numbers\n",
 541                                  session->name, session->nr_oos_count);
 542                 }
 543                 if (!session->reorder_skip) {
 544                         atomic_long_inc(&session->stats.rx_seq_discards);
 545                         l2tp_dbg(session, L2TP_MSG_SEQ,
 546                                  "%s: oos pkt %u len %d discarded, waiting for %u, reorder_q_len=%d\n",
 547                                  session->name, L2TP_SKB_CB(skb)->ns,
 548                                  L2TP_SKB_CB(skb)->length, session->nr,
 549                                  skb_queue_len(&session->reorder_q));
 550                         goto discard;
 551                 }
 552                 skb_queue_tail(&session->reorder_q, skb);
 553         }
 554 
 555 out:
 556         return 0;
 557 
 558 discard:
 559         return 1;
 560 }
 561 
 562 /* Do receive processing of L2TP data frames. We handle both L2TPv2
 563  * and L2TPv3 data frames here.
 564  *
 565  * L2TPv2 Data Message Header
 566  *
 567  *  0                   1                   2                   3
 568  *  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
 569  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 570  * |T|L|x|x|S|x|O|P|x|x|x|x|  Ver  |          Length (opt)         |
 571  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 572  * |           Tunnel ID           |           Session ID          |
 573  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 574  * |             Ns (opt)          |             Nr (opt)          |
 575  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 576  * |      Offset Size (opt)        |    Offset pad... (opt)
 577  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 578  *
 579  * Data frames are marked by T=0. All other fields are the same as
 580  * those in L2TP control frames.
 581  *
 582  * L2TPv3 Data Message Header
 583  *
 584  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 585  * |                      L2TP Session Header                      |
 586  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 587  * |                      L2-Specific Sublayer                     |
 588  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 589  * |                        Tunnel Payload                      ...
 590  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 591  *
 592  * L2TPv3 Session Header Over IP
 593  *
 594  *  0                   1                   2                   3
 595  *  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
 596  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 597  * |                           Session ID                          |
 598  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 599  * |               Cookie (optional, maximum 64 bits)...
 600  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 601  *                                                                 |
 602  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 603  *
 604  * L2TPv3 L2-Specific Sublayer Format
 605  *
 606  *  0                   1                   2                   3
 607  *  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
 608  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 609  * |x|S|x|x|x|x|x|x|              Sequence Number                  |
 610  * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 611  *
 612  * Cookie value and sublayer format are negotiated with the peer when
 613  * the session is set up. Unlike L2TPv2, we do not need to parse the
 614  * packet header to determine if optional fields are present.
 615  *
 616  * Caller must already have parsed the frame and determined that it is
 617  * a data (not control) frame before coming here. Fields up to the
 618  * session-id have already been parsed and ptr points to the data
 619  * after the session-id.
 620  */
 621 void l2tp_recv_common(struct l2tp_session *session, struct sk_buff *skb,
 622                       unsigned char *ptr, unsigned char *optr, u16 hdrflags,
 623                       int length)
 624 {
 625         struct l2tp_tunnel *tunnel = session->tunnel;
 626         int offset;
 627         u32 ns, nr;
 628 
 629         /* Parse and check optional cookie */
 630         if (session->peer_cookie_len > 0) {
 631                 if (memcmp(ptr, &session->peer_cookie[0], session->peer_cookie_len)) {
 632                         l2tp_info(tunnel, L2TP_MSG_DATA,
 633                                   "%s: cookie mismatch (%u/%u). Discarding.\n",
 634                                   tunnel->name, tunnel->tunnel_id,
 635                                   session->session_id);
 636                         atomic_long_inc(&session->stats.rx_cookie_discards);
 637                         goto discard;
 638                 }
 639                 ptr += session->peer_cookie_len;
 640         }
 641 
 642         /* Handle the optional sequence numbers. Sequence numbers are
 643          * in different places for L2TPv2 and L2TPv3.
 644          *
 645          * If we are the LAC, enable/disable sequence numbers under
 646          * the control of the LNS.  If no sequence numbers present but
 647          * we were expecting them, discard frame.
 648          */
 649         ns = nr = 0;
 650         L2TP_SKB_CB(skb)->has_seq = 0;
 651         if (tunnel->version == L2TP_HDR_VER_2) {
 652                 if (hdrflags & L2TP_HDRFLAG_S) {
 653                         ns = ntohs(*(__be16 *) ptr);
 654                         ptr += 2;
 655                         nr = ntohs(*(__be16 *) ptr);
 656                         ptr += 2;
 657 
 658                         /* Store L2TP info in the skb */
 659                         L2TP_SKB_CB(skb)->ns = ns;
 660                         L2TP_SKB_CB(skb)->has_seq = 1;
 661 
 662                         l2tp_dbg(session, L2TP_MSG_SEQ,
 663                                  "%s: recv data ns=%u, nr=%u, session nr=%u\n",
 664                                  session->name, ns, nr, session->nr);
 665                 }
 666         } else if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
 667                 u32 l2h = ntohl(*(__be32 *) ptr);
 668 
 669                 if (l2h & 0x40000000) {
 670                         ns = l2h & 0x00ffffff;
 671 
 672                         /* Store L2TP info in the skb */
 673                         L2TP_SKB_CB(skb)->ns = ns;
 674                         L2TP_SKB_CB(skb)->has_seq = 1;
 675 
 676                         l2tp_dbg(session, L2TP_MSG_SEQ,
 677                                  "%s: recv data ns=%u, session nr=%u\n",
 678                                  session->name, ns, session->nr);
 679                 }
 680                 ptr += 4;
 681         }
 682 
 683         if (L2TP_SKB_CB(skb)->has_seq) {
 684                 /* Received a packet with sequence numbers. If we're the LNS,
 685                  * check if we sre sending sequence numbers and if not,
 686                  * configure it so.
 687                  */
 688                 if ((!session->lns_mode) && (!session->send_seq)) {
 689                         l2tp_info(session, L2TP_MSG_SEQ,
 690                                   "%s: requested to enable seq numbers by LNS\n",
 691                                   session->name);
 692                         session->send_seq = 1;
 693                         l2tp_session_set_header_len(session, tunnel->version);
 694                 }
 695         } else {
 696                 /* No sequence numbers.
 697                  * If user has configured mandatory sequence numbers, discard.
 698                  */
 699                 if (session->recv_seq) {
 700                         l2tp_warn(session, L2TP_MSG_SEQ,
 701                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 702                                   session->name);
 703                         atomic_long_inc(&session->stats.rx_seq_discards);
 704                         goto discard;
 705                 }
 706 
 707                 /* If we're the LAC and we're sending sequence numbers, the
 708                  * LNS has requested that we no longer send sequence numbers.
 709                  * If we're the LNS and we're sending sequence numbers, the
 710                  * LAC is broken. Discard the frame.
 711                  */
 712                 if ((!session->lns_mode) && (session->send_seq)) {
 713                         l2tp_info(session, L2TP_MSG_SEQ,
 714                                   "%s: requested to disable seq numbers by LNS\n",
 715                                   session->name);
 716                         session->send_seq = 0;
 717                         l2tp_session_set_header_len(session, tunnel->version);
 718                 } else if (session->send_seq) {
 719                         l2tp_warn(session, L2TP_MSG_SEQ,
 720                                   "%s: recv data has no seq numbers when required. Discarding.\n",
 721                                   session->name);
 722                         atomic_long_inc(&session->stats.rx_seq_discards);
 723                         goto discard;
 724                 }
 725         }
 726 
 727         /* Session data offset is defined only for L2TPv2 and is
 728          * indicated by an optional 16-bit value in the header.
 729          */
 730         if (tunnel->version == L2TP_HDR_VER_2) {
 731                 /* If offset bit set, skip it. */
 732                 if (hdrflags & L2TP_HDRFLAG_O) {
 733                         offset = ntohs(*(__be16 *)ptr);
 734                         ptr += 2 + offset;
 735                 }
 736         }
 737 
 738         offset = ptr - optr;
 739         if (!pskb_may_pull(skb, offset))
 740                 goto discard;
 741 
 742         __skb_pull(skb, offset);
 743 
 744         /* Prepare skb for adding to the session's reorder_q.  Hold
 745          * packets for max reorder_timeout or 1 second if not
 746          * reordering.
 747          */
 748         L2TP_SKB_CB(skb)->length = length;
 749         L2TP_SKB_CB(skb)->expires = jiffies +
 750                 (session->reorder_timeout ? session->reorder_timeout : HZ);
 751 
 752         /* Add packet to the session's receive queue. Reordering is done here, if
 753          * enabled. Saved L2TP protocol info is stored in skb->sb[].
 754          */
 755         if (L2TP_SKB_CB(skb)->has_seq) {
 756                 if (l2tp_recv_data_seq(session, skb))
 757                         goto discard;
 758         } else {
 759                 /* No sequence numbers. Add the skb to the tail of the
 760                  * reorder queue. This ensures that it will be
 761                  * delivered after all previous sequenced skbs.
 762                  */
 763                 skb_queue_tail(&session->reorder_q, skb);
 764         }
 765 
 766         /* Try to dequeue as many skbs from reorder_q as we can. */
 767         l2tp_recv_dequeue(session);
 768 
 769         return;
 770 
 771 discard:
 772         atomic_long_inc(&session->stats.rx_errors);
 773         kfree_skb(skb);
 774 }
 775 EXPORT_SYMBOL(l2tp_recv_common);
 776 
 777 /* Drop skbs from the session's reorder_q
 778  */
 779 static int l2tp_session_queue_purge(struct l2tp_session *session)
 780 {
 781         struct sk_buff *skb = NULL;
 782         BUG_ON(!session);
 783         BUG_ON(session->magic != L2TP_SESSION_MAGIC);
 784         while ((skb = skb_dequeue(&session->reorder_q))) {
 785                 atomic_long_inc(&session->stats.rx_errors);
 786                 kfree_skb(skb);
 787         }
 788         return 0;
 789 }
 790 
 791 /* Internal UDP receive frame. Do the real work of receiving an L2TP data frame
 792  * here. The skb is not on a list when we get here.
 793  * Returns 0 if the packet was a data packet and was successfully passed on.
 794  * Returns 1 if the packet was not a good data packet and could not be
 795  * forwarded.  All such packets are passed up to userspace to deal with.
 796  */
 797 static int l2tp_udp_recv_core(struct l2tp_tunnel *tunnel, struct sk_buff *skb)
 798 {
 799         struct l2tp_session *session = NULL;
 800         unsigned char *ptr, *optr;
 801         u16 hdrflags;
 802         u32 tunnel_id, session_id;
 803         u16 version;
 804         int length;
 805 
 806         /* UDP has verifed checksum */
 807 
 808         /* UDP always verifies the packet length. */
 809         __skb_pull(skb, sizeof(struct udphdr));
 810 
 811         /* Short packet? */
 812         if (!pskb_may_pull(skb, L2TP_HDR_SIZE_MAX)) {
 813                 l2tp_info(tunnel, L2TP_MSG_DATA,
 814                           "%s: recv short packet (len=%d)\n",
 815                           tunnel->name, skb->len);
 816                 goto error;
 817         }
 818 
 819         /* Trace packet contents, if enabled */
 820         if (tunnel->debug & L2TP_MSG_DATA) {
 821                 length = min(32u, skb->len);
 822                 if (!pskb_may_pull(skb, length))
 823                         goto error;
 824 
 825                 pr_debug("%s: recv\n", tunnel->name);
 826                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET, skb->data, length);
 827         }
 828 
 829         /* Point to L2TP header */
 830         optr = ptr = skb->data;
 831 
 832         /* Get L2TP header flags */
 833         hdrflags = ntohs(*(__be16 *) ptr);
 834 
 835         /* Check protocol version */
 836         version = hdrflags & L2TP_HDR_VER_MASK;
 837         if (version != tunnel->version) {
 838                 l2tp_info(tunnel, L2TP_MSG_DATA,
 839                           "%s: recv protocol version mismatch: got %d expected %d\n",
 840                           tunnel->name, version, tunnel->version);
 841                 goto error;
 842         }
 843 
 844         /* Get length of L2TP packet */
 845         length = skb->len;
 846 
 847         /* If type is control packet, it is handled by userspace. */
 848         if (hdrflags & L2TP_HDRFLAG_T) {
 849                 l2tp_dbg(tunnel, L2TP_MSG_DATA,
 850                          "%s: recv control packet, len=%d\n",
 851                          tunnel->name, length);
 852                 goto error;
 853         }
 854 
 855         /* Skip flags */
 856         ptr += 2;
 857 
 858         if (tunnel->version == L2TP_HDR_VER_2) {
 859                 /* If length is present, skip it */
 860                 if (hdrflags & L2TP_HDRFLAG_L)
 861                         ptr += 2;
 862 
 863                 /* Extract tunnel and session ID */
 864                 tunnel_id = ntohs(*(__be16 *) ptr);
 865                 ptr += 2;
 866                 session_id = ntohs(*(__be16 *) ptr);
 867                 ptr += 2;
 868         } else {
 869                 ptr += 2;       /* skip reserved bits */
 870                 tunnel_id = tunnel->tunnel_id;
 871                 session_id = ntohl(*(__be32 *) ptr);
 872                 ptr += 4;
 873         }
 874 
 875         /* Find the session context */
 876         session = l2tp_tunnel_get_session(tunnel, session_id);
 877         if (!session || !session->recv_skb) {
 878                 if (session)
 879                         l2tp_session_dec_refcount(session);
 880 
 881                 /* Not found? Pass to userspace to deal with */
 882                 l2tp_info(tunnel, L2TP_MSG_DATA,
 883                           "%s: no session found (%u/%u). Passing up.\n",
 884                           tunnel->name, tunnel_id, session_id);
 885                 goto error;
 886         }
 887 
 888         if (tunnel->version == L2TP_HDR_VER_3 &&
 889             l2tp_v3_ensure_opt_in_linear(session, skb, &ptr, &optr))
 890                 goto error;
 891 
 892         l2tp_recv_common(session, skb, ptr, optr, hdrflags, length);
 893         l2tp_session_dec_refcount(session);
 894 
 895         return 0;
 896 
 897 error:
 898         /* Put UDP header back */
 899         __skb_push(skb, sizeof(struct udphdr));
 900 
 901         return 1;
 902 }
 903 
 904 /* UDP encapsulation receive handler. See net/ipv4/udp.c.
 905  * Return codes:
 906  * 0 : success.
 907  * <0: error
 908  * >0: skb should be passed up to userspace as UDP.
 909  */
 910 int l2tp_udp_encap_recv(struct sock *sk, struct sk_buff *skb)
 911 {
 912         struct l2tp_tunnel *tunnel;
 913 
 914         tunnel = rcu_dereference_sk_user_data(sk);
 915         if (tunnel == NULL)
 916                 goto pass_up;
 917 
 918         l2tp_dbg(tunnel, L2TP_MSG_DATA, "%s: received %d bytes\n",
 919                  tunnel->name, skb->len);
 920 
 921         if (l2tp_udp_recv_core(tunnel, skb))
 922                 goto pass_up;
 923 
 924         return 0;
 925 
 926 pass_up:
 927         return 1;
 928 }
 929 EXPORT_SYMBOL_GPL(l2tp_udp_encap_recv);
 930 
 931 /************************************************************************
 932  * Transmit handling
 933  ***********************************************************************/
 934 
 935 /* Build an L2TP header for the session into the buffer provided.
 936  */
 937 static int l2tp_build_l2tpv2_header(struct l2tp_session *session, void *buf)
 938 {
 939         struct l2tp_tunnel *tunnel = session->tunnel;
 940         __be16 *bufp = buf;
 941         __be16 *optr = buf;
 942         u16 flags = L2TP_HDR_VER_2;
 943         u32 tunnel_id = tunnel->peer_tunnel_id;
 944         u32 session_id = session->peer_session_id;
 945 
 946         if (session->send_seq)
 947                 flags |= L2TP_HDRFLAG_S;
 948 
 949         /* Setup L2TP header. */
 950         *bufp++ = htons(flags);
 951         *bufp++ = htons(tunnel_id);
 952         *bufp++ = htons(session_id);
 953         if (session->send_seq) {
 954                 *bufp++ = htons(session->ns);
 955                 *bufp++ = 0;
 956                 session->ns++;
 957                 session->ns &= 0xffff;
 958                 l2tp_dbg(session, L2TP_MSG_SEQ, "%s: updated ns to %u\n",
 959                          session->name, session->ns);
 960         }
 961 
 962         return bufp - optr;
 963 }
 964 
 965 static int l2tp_build_l2tpv3_header(struct l2tp_session *session, void *buf)
 966 {
 967         struct l2tp_tunnel *tunnel = session->tunnel;
 968         char *bufp = buf;
 969         char *optr = bufp;
 970 
 971         /* Setup L2TP header. The header differs slightly for UDP and
 972          * IP encapsulations. For UDP, there is 4 bytes of flags.
 973          */
 974         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
 975                 u16 flags = L2TP_HDR_VER_3;
 976                 *((__be16 *) bufp) = htons(flags);
 977                 bufp += 2;
 978                 *((__be16 *) bufp) = 0;
 979                 bufp += 2;
 980         }
 981 
 982         *((__be32 *) bufp) = htonl(session->peer_session_id);
 983         bufp += 4;
 984         if (session->cookie_len) {
 985                 memcpy(bufp, &session->cookie[0], session->cookie_len);
 986                 bufp += session->cookie_len;
 987         }
 988         if (session->l2specific_type == L2TP_L2SPECTYPE_DEFAULT) {
 989                 u32 l2h = 0;
 990 
 991                 if (session->send_seq) {
 992                         l2h = 0x40000000 | session->ns;
 993                         session->ns++;
 994                         session->ns &= 0xffffff;
 995                         l2tp_dbg(session, L2TP_MSG_SEQ,
 996                                  "%s: updated ns to %u\n",
 997                                  session->name, session->ns);
 998                 }
 999 
1000                 *((__be32 *)bufp) = htonl(l2h);
1001                 bufp += 4;
1002         }
1003 
1004         return bufp - optr;
1005 }
1006 
1007 static void l2tp_xmit_core(struct l2tp_session *session, struct sk_buff *skb,
1008                            struct flowi *fl, size_t data_len)
1009 {
1010         struct l2tp_tunnel *tunnel = session->tunnel;
1011         unsigned int len = skb->len;
1012         int error;
1013 
1014         /* Debug */
1015         if (session->send_seq)
1016                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes, ns=%u\n",
1017                          session->name, data_len, session->ns - 1);
1018         else
1019                 l2tp_dbg(session, L2TP_MSG_DATA, "%s: send %zd bytes\n",
1020                          session->name, data_len);
1021 
1022         if (session->debug & L2TP_MSG_DATA) {
1023                 int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1024                 unsigned char *datap = skb->data + uhlen;
1025 
1026                 pr_debug("%s: xmit\n", session->name);
1027                 print_hex_dump_bytes("", DUMP_PREFIX_OFFSET,
1028                                      datap, min_t(size_t, 32, len - uhlen));
1029         }
1030 
1031         /* Queue the packet to IP for output */
1032         skb->ignore_df = 1;
1033 #if IS_ENABLED(CONFIG_IPV6)
1034         if (l2tp_sk_is_v6(tunnel->sock))
1035                 error = inet6_csk_xmit(tunnel->sock, skb, NULL);
1036         else
1037 #endif
1038                 error = ip_queue_xmit(tunnel->sock, skb, fl);
1039 
1040         /* Update stats */
1041         if (error >= 0) {
1042                 atomic_long_inc(&tunnel->stats.tx_packets);
1043                 atomic_long_add(len, &tunnel->stats.tx_bytes);
1044                 atomic_long_inc(&session->stats.tx_packets);
1045                 atomic_long_add(len, &session->stats.tx_bytes);
1046         } else {
1047                 atomic_long_inc(&tunnel->stats.tx_errors);
1048                 atomic_long_inc(&session->stats.tx_errors);
1049         }
1050 }
1051 
1052 /* If caller requires the skb to have a ppp header, the header must be
1053  * inserted in the skb data before calling this function.
1054  */
1055 int l2tp_xmit_skb(struct l2tp_session *session, struct sk_buff *skb, int hdr_len)
1056 {
1057         int data_len = skb->len;
1058         struct l2tp_tunnel *tunnel = session->tunnel;
1059         struct sock *sk = tunnel->sock;
1060         struct flowi *fl;
1061         struct udphdr *uh;
1062         struct inet_sock *inet;
1063         int headroom;
1064         int uhlen = (tunnel->encap == L2TP_ENCAPTYPE_UDP) ? sizeof(struct udphdr) : 0;
1065         int udp_len;
1066         int ret = NET_XMIT_SUCCESS;
1067 
1068         /* Check that there's enough headroom in the skb to insert IP,
1069          * UDP and L2TP headers. If not enough, expand it to
1070          * make room. Adjust truesize.
1071          */
1072         headroom = NET_SKB_PAD + sizeof(struct iphdr) +
1073                 uhlen + hdr_len;
1074         if (skb_cow_head(skb, headroom)) {
1075                 kfree_skb(skb);
1076                 return NET_XMIT_DROP;
1077         }
1078 
1079         /* Setup L2TP header */
1080         session->build_header(session, __skb_push(skb, hdr_len));
1081 
1082         /* Reset skb netfilter state */
1083         memset(&(IPCB(skb)->opt), 0, sizeof(IPCB(skb)->opt));
1084         IPCB(skb)->flags &= ~(IPSKB_XFRM_TUNNEL_SIZE | IPSKB_XFRM_TRANSFORMED |
1085                               IPSKB_REROUTED);
1086         nf_reset_ct(skb);
1087 
1088         bh_lock_sock(sk);
1089         if (sock_owned_by_user(sk)) {
1090                 kfree_skb(skb);
1091                 ret = NET_XMIT_DROP;
1092                 goto out_unlock;
1093         }
1094 
1095         /* The user-space may change the connection status for the user-space
1096          * provided socket at run time: we must check it under the socket lock
1097          */
1098         if (tunnel->fd >= 0 && sk->sk_state != TCP_ESTABLISHED) {
1099                 kfree_skb(skb);
1100                 ret = NET_XMIT_DROP;
1101                 goto out_unlock;
1102         }
1103 
1104         /* Get routing info from the tunnel socket */
1105         skb_dst_drop(skb);
1106         skb_dst_set(skb, sk_dst_check(sk, 0));
1107 
1108         inet = inet_sk(sk);
1109         fl = &inet->cork.fl;
1110         switch (tunnel->encap) {
1111         case L2TP_ENCAPTYPE_UDP:
1112                 /* Setup UDP header */
1113                 __skb_push(skb, sizeof(*uh));
1114                 skb_reset_transport_header(skb);
1115                 uh = udp_hdr(skb);
1116                 uh->source = inet->inet_sport;
1117                 uh->dest = inet->inet_dport;
1118                 udp_len = uhlen + hdr_len + data_len;
1119                 uh->len = htons(udp_len);
1120 
1121                 /* Calculate UDP checksum if configured to do so */
1122 #if IS_ENABLED(CONFIG_IPV6)
1123                 if (l2tp_sk_is_v6(sk))
1124                         udp6_set_csum(udp_get_no_check6_tx(sk),
1125                                       skb, &inet6_sk(sk)->saddr,
1126                                       &sk->sk_v6_daddr, udp_len);
1127                 else
1128 #endif
1129                 udp_set_csum(sk->sk_no_check_tx, skb, inet->inet_saddr,
1130                              inet->inet_daddr, udp_len);
1131                 break;
1132 
1133         case L2TP_ENCAPTYPE_IP:
1134                 break;
1135         }
1136 
1137         l2tp_xmit_core(session, skb, fl, data_len);
1138 out_unlock:
1139         bh_unlock_sock(sk);
1140 
1141         return ret;
1142 }
1143 EXPORT_SYMBOL_GPL(l2tp_xmit_skb);
1144 
1145 /*****************************************************************************
1146  * Tinnel and session create/destroy.
1147  *****************************************************************************/
1148 
1149 /* Tunnel socket destruct hook.
1150  * The tunnel context is deleted only when all session sockets have been
1151  * closed.
1152  */
1153 static void l2tp_tunnel_destruct(struct sock *sk)
1154 {
1155         struct l2tp_tunnel *tunnel = l2tp_tunnel(sk);
1156 
1157         if (tunnel == NULL)
1158                 goto end;
1159 
1160         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing...\n", tunnel->name);
1161 
1162         /* Disable udp encapsulation */
1163         switch (tunnel->encap) {
1164         case L2TP_ENCAPTYPE_UDP:
1165                 /* No longer an encapsulation socket. See net/ipv4/udp.c */
1166                 (udp_sk(sk))->encap_type = 0;
1167                 (udp_sk(sk))->encap_rcv = NULL;
1168                 (udp_sk(sk))->encap_destroy = NULL;
1169                 break;
1170         case L2TP_ENCAPTYPE_IP:
1171                 break;
1172         }
1173 
1174         /* Remove hooks into tunnel socket */
1175         sk->sk_destruct = tunnel->old_sk_destruct;
1176         sk->sk_user_data = NULL;
1177 
1178         /* Call the original destructor */
1179         if (sk->sk_destruct)
1180                 (*sk->sk_destruct)(sk);
1181 
1182         kfree_rcu(tunnel, rcu);
1183 end:
1184         return;
1185 }
1186 
1187 /* When the tunnel is closed, all the attached sessions need to go too.
1188  */
1189 static void l2tp_tunnel_closeall(struct l2tp_tunnel *tunnel)
1190 {
1191         int hash;
1192         struct hlist_node *walk;
1193         struct hlist_node *tmp;
1194         struct l2tp_session *session;
1195 
1196         BUG_ON(tunnel == NULL);
1197 
1198         l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: closing all sessions...\n",
1199                   tunnel->name);
1200 
1201         write_lock_bh(&tunnel->hlist_lock);
1202         tunnel->acpt_newsess = false;
1203         for (hash = 0; hash < L2TP_HASH_SIZE; hash++) {
1204 again:
1205                 hlist_for_each_safe(walk, tmp, &tunnel->session_hlist[hash]) {
1206                         session = hlist_entry(walk, struct l2tp_session, hlist);
1207 
1208                         l2tp_info(session, L2TP_MSG_CONTROL,
1209                                   "%s: closing session\n", session->name);
1210 
1211                         hlist_del_init(&session->hlist);
1212 
1213                         if (test_and_set_bit(0, &session->dead))
1214                                 goto again;
1215 
1216                         write_unlock_bh(&tunnel->hlist_lock);
1217 
1218                         __l2tp_session_unhash(session);
1219                         l2tp_session_queue_purge(session);
1220 
1221                         if (session->session_close != NULL)
1222                                 (*session->session_close)(session);
1223 
1224                         l2tp_session_dec_refcount(session);
1225 
1226                         write_lock_bh(&tunnel->hlist_lock);
1227 
1228                         /* Now restart from the beginning of this hash
1229                          * chain.  We always remove a session from the
1230                          * list so we are guaranteed to make forward
1231                          * progress.
1232                          */
1233                         goto again;
1234                 }
1235         }
1236         write_unlock_bh(&tunnel->hlist_lock);
1237 }
1238 
1239 /* Tunnel socket destroy hook for UDP encapsulation */
1240 static void l2tp_udp_encap_destroy(struct sock *sk)
1241 {
1242         struct l2tp_tunnel *tunnel = l2tp_tunnel(sk);
1243 
1244         if (tunnel)
1245                 l2tp_tunnel_delete(tunnel);
1246 }
1247 
1248 /* Workqueue tunnel deletion function */
1249 static void l2tp_tunnel_del_work(struct work_struct *work)
1250 {
1251         struct l2tp_tunnel *tunnel = container_of(work, struct l2tp_tunnel,
1252                                                   del_work);
1253         struct sock *sk = tunnel->sock;
1254         struct socket *sock = sk->sk_socket;
1255         struct l2tp_net *pn;
1256 
1257         l2tp_tunnel_closeall(tunnel);
1258 
1259         /* If the tunnel socket was created within the kernel, use
1260          * the sk API to release it here.
1261          */
1262         if (tunnel->fd < 0) {
1263                 if (sock) {
1264                         kernel_sock_shutdown(sock, SHUT_RDWR);
1265                         sock_release(sock);
1266                 }
1267         }
1268 
1269         /* Remove the tunnel struct from the tunnel list */
1270         pn = l2tp_pernet(tunnel->l2tp_net);
1271         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1272         list_del_rcu(&tunnel->list);
1273         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1274 
1275         /* drop initial ref */
1276         l2tp_tunnel_dec_refcount(tunnel);
1277 
1278         /* drop workqueue ref */
1279         l2tp_tunnel_dec_refcount(tunnel);
1280 }
1281 
1282 /* Create a socket for the tunnel, if one isn't set up by
1283  * userspace. This is used for static tunnels where there is no
1284  * managing L2TP daemon.
1285  *
1286  * Since we don't want these sockets to keep a namespace alive by
1287  * themselves, we drop the socket's namespace refcount after creation.
1288  * These sockets are freed when the namespace exits using the pernet
1289  * exit hook.
1290  */
1291 static int l2tp_tunnel_sock_create(struct net *net,
1292                                 u32 tunnel_id,
1293                                 u32 peer_tunnel_id,
1294                                 struct l2tp_tunnel_cfg *cfg,
1295                                 struct socket **sockp)
1296 {
1297         int err = -EINVAL;
1298         struct socket *sock = NULL;
1299         struct udp_port_cfg udp_conf;
1300 
1301         switch (cfg->encap) {
1302         case L2TP_ENCAPTYPE_UDP:
1303                 memset(&udp_conf, 0, sizeof(udp_conf));
1304 
1305 #if IS_ENABLED(CONFIG_IPV6)
1306                 if (cfg->local_ip6 && cfg->peer_ip6) {
1307                         udp_conf.family = AF_INET6;
1308                         memcpy(&udp_conf.local_ip6, cfg->local_ip6,
1309                                sizeof(udp_conf.local_ip6));
1310                         memcpy(&udp_conf.peer_ip6, cfg->peer_ip6,
1311                                sizeof(udp_conf.peer_ip6));
1312                         udp_conf.use_udp6_tx_checksums =
1313                           ! cfg->udp6_zero_tx_checksums;
1314                         udp_conf.use_udp6_rx_checksums =
1315                           ! cfg->udp6_zero_rx_checksums;
1316                 } else
1317 #endif
1318                 {
1319                         udp_conf.family = AF_INET;
1320                         udp_conf.local_ip = cfg->local_ip;
1321                         udp_conf.peer_ip = cfg->peer_ip;
1322                         udp_conf.use_udp_checksums = cfg->use_udp_checksums;
1323                 }
1324 
1325                 udp_conf.local_udp_port = htons(cfg->local_udp_port);
1326                 udp_conf.peer_udp_port = htons(cfg->peer_udp_port);
1327 
1328                 err = udp_sock_create(net, &udp_conf, &sock);
1329                 if (err < 0)
1330                         goto out;
1331 
1332                 break;
1333 
1334         case L2TP_ENCAPTYPE_IP:
1335 #if IS_ENABLED(CONFIG_IPV6)
1336                 if (cfg->local_ip6 && cfg->peer_ip6) {
1337                         struct sockaddr_l2tpip6 ip6_addr = {0};
1338 
1339                         err = sock_create_kern(net, AF_INET6, SOCK_DGRAM,
1340                                           IPPROTO_L2TP, &sock);
1341                         if (err < 0)
1342                                 goto out;
1343 
1344                         ip6_addr.l2tp_family = AF_INET6;
1345                         memcpy(&ip6_addr.l2tp_addr, cfg->local_ip6,
1346                                sizeof(ip6_addr.l2tp_addr));
1347                         ip6_addr.l2tp_conn_id = tunnel_id;
1348                         err = kernel_bind(sock, (struct sockaddr *) &ip6_addr,
1349                                           sizeof(ip6_addr));
1350                         if (err < 0)
1351                                 goto out;
1352 
1353                         ip6_addr.l2tp_family = AF_INET6;
1354                         memcpy(&ip6_addr.l2tp_addr, cfg->peer_ip6,
1355                                sizeof(ip6_addr.l2tp_addr));
1356                         ip6_addr.l2tp_conn_id = peer_tunnel_id;
1357                         err = kernel_connect(sock,
1358                                              (struct sockaddr *) &ip6_addr,
1359                                              sizeof(ip6_addr), 0);
1360                         if (err < 0)
1361                                 goto out;
1362                 } else
1363 #endif
1364                 {
1365                         struct sockaddr_l2tpip ip_addr = {0};
1366 
1367                         err = sock_create_kern(net, AF_INET, SOCK_DGRAM,
1368                                           IPPROTO_L2TP, &sock);
1369                         if (err < 0)
1370                                 goto out;
1371 
1372                         ip_addr.l2tp_family = AF_INET;
1373                         ip_addr.l2tp_addr = cfg->local_ip;
1374                         ip_addr.l2tp_conn_id = tunnel_id;
1375                         err = kernel_bind(sock, (struct sockaddr *) &ip_addr,
1376                                           sizeof(ip_addr));
1377                         if (err < 0)
1378                                 goto out;
1379 
1380                         ip_addr.l2tp_family = AF_INET;
1381                         ip_addr.l2tp_addr = cfg->peer_ip;
1382                         ip_addr.l2tp_conn_id = peer_tunnel_id;
1383                         err = kernel_connect(sock, (struct sockaddr *) &ip_addr,
1384                                              sizeof(ip_addr), 0);
1385                         if (err < 0)
1386                                 goto out;
1387                 }
1388                 break;
1389 
1390         default:
1391                 goto out;
1392         }
1393 
1394 out:
1395         *sockp = sock;
1396         if ((err < 0) && sock) {
1397                 kernel_sock_shutdown(sock, SHUT_RDWR);
1398                 sock_release(sock);
1399                 *sockp = NULL;
1400         }
1401 
1402         return err;
1403 }
1404 
1405 static struct lock_class_key l2tp_socket_class;
1406 
1407 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)
1408 {
1409         struct l2tp_tunnel *tunnel = NULL;
1410         int err;
1411         enum l2tp_encap_type encap = L2TP_ENCAPTYPE_UDP;
1412 
1413         if (cfg != NULL)
1414                 encap = cfg->encap;
1415 
1416         tunnel = kzalloc(sizeof(struct l2tp_tunnel), GFP_KERNEL);
1417         if (tunnel == NULL) {
1418                 err = -ENOMEM;
1419                 goto err;
1420         }
1421 
1422         tunnel->version = version;
1423         tunnel->tunnel_id = tunnel_id;
1424         tunnel->peer_tunnel_id = peer_tunnel_id;
1425         tunnel->debug = L2TP_DEFAULT_DEBUG_FLAGS;
1426 
1427         tunnel->magic = L2TP_TUNNEL_MAGIC;
1428         sprintf(&tunnel->name[0], "tunl %u", tunnel_id);
1429         rwlock_init(&tunnel->hlist_lock);
1430         tunnel->acpt_newsess = true;
1431 
1432         if (cfg != NULL)
1433                 tunnel->debug = cfg->debug;
1434 
1435         tunnel->encap = encap;
1436 
1437         refcount_set(&tunnel->ref_count, 1);
1438         tunnel->fd = fd;
1439 
1440         /* Init delete workqueue struct */
1441         INIT_WORK(&tunnel->del_work, l2tp_tunnel_del_work);
1442 
1443         INIT_LIST_HEAD(&tunnel->list);
1444 
1445         err = 0;
1446 err:
1447         if (tunnelp)
1448                 *tunnelp = tunnel;
1449 
1450         return err;
1451 }
1452 EXPORT_SYMBOL_GPL(l2tp_tunnel_create);
1453 
1454 static int l2tp_validate_socket(const struct sock *sk, const struct net *net,
1455                                 enum l2tp_encap_type encap)
1456 {
1457         if (!net_eq(sock_net(sk), net))
1458                 return -EINVAL;
1459 
1460         if (sk->sk_type != SOCK_DGRAM)
1461                 return -EPROTONOSUPPORT;
1462 
1463         if (sk->sk_family != PF_INET && sk->sk_family != PF_INET6)
1464                 return -EPROTONOSUPPORT;
1465 
1466         if ((encap == L2TP_ENCAPTYPE_UDP && sk->sk_protocol != IPPROTO_UDP) ||
1467             (encap == L2TP_ENCAPTYPE_IP && sk->sk_protocol != IPPROTO_L2TP))
1468                 return -EPROTONOSUPPORT;
1469 
1470         if (sk->sk_user_data)
1471                 return -EBUSY;
1472 
1473         return 0;
1474 }
1475 
1476 int l2tp_tunnel_register(struct l2tp_tunnel *tunnel, struct net *net,
1477                          struct l2tp_tunnel_cfg *cfg)
1478 {
1479         struct l2tp_tunnel *tunnel_walk;
1480         struct l2tp_net *pn;
1481         struct socket *sock;
1482         struct sock *sk;
1483         int ret;
1484 
1485         if (tunnel->fd < 0) {
1486                 ret = l2tp_tunnel_sock_create(net, tunnel->tunnel_id,
1487                                               tunnel->peer_tunnel_id, cfg,
1488                                               &sock);
1489                 if (ret < 0)
1490                         goto err;
1491         } else {
1492                 sock = sockfd_lookup(tunnel->fd, &ret);
1493                 if (!sock)
1494                         goto err;
1495 
1496                 ret = l2tp_validate_socket(sock->sk, net, tunnel->encap);
1497                 if (ret < 0)
1498                         goto err_sock;
1499         }
1500 
1501         tunnel->l2tp_net = net;
1502         pn = l2tp_pernet(net);
1503 
1504         spin_lock_bh(&pn->l2tp_tunnel_list_lock);
1505         list_for_each_entry(tunnel_walk, &pn->l2tp_tunnel_list, list) {
1506                 if (tunnel_walk->tunnel_id == tunnel->tunnel_id) {
1507                         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1508 
1509                         ret = -EEXIST;
1510                         goto err_sock;
1511                 }
1512         }
1513         list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
1514         spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
1515 
1516         sk = sock->sk;
1517         sock_hold(sk);
1518         tunnel->sock = sk;
1519 
1520         if (tunnel->encap == L2TP_ENCAPTYPE_UDP) {
1521                 struct udp_tunnel_sock_cfg udp_cfg = {
1522                         .sk_user_data = tunnel,
1523                         .encap_type = UDP_ENCAP_L2TPINUDP,
1524                         .encap_rcv = l2tp_udp_encap_recv,
1525                         .encap_destroy = l2tp_udp_encap_destroy,
1526                 };
1527 
1528                 setup_udp_tunnel_sock(net, sock, &udp_cfg);
1529         } else {
1530                 sk->sk_user_data = tunnel;
1531         }
1532 
1533         tunnel->old_sk_destruct = sk->sk_destruct;
1534         sk->sk_destruct = &l2tp_tunnel_destruct;
1535         lockdep_set_class_and_name(&sk->sk_lock.slock, &l2tp_socket_class,
1536                                    "l2tp_sock");
1537         sk->sk_allocation = GFP_ATOMIC;
1538 
1539         if (tunnel->fd >= 0)
1540                 sockfd_put(sock);
1541 
1542         return 0;
1543 
1544 err_sock:
1545         if (tunnel->fd < 0)
1546                 sock_release(sock);
1547         else
1548                 sockfd_put(sock);
1549 err:
1550         return ret;
1551 }
1552 EXPORT_SYMBOL_GPL(l2tp_tunnel_register);
1553 
1554 /* This function is used by the netlink TUNNEL_DELETE command.
1555  */
1556 void l2tp_tunnel_delete(struct l2tp_tunnel *tunnel)
1557 {
1558         if (!test_and_set_bit(0, &tunnel->dead)) {
1559                 l2tp_tunnel_inc_refcount(tunnel);
1560                 queue_work(l2tp_wq, &tunnel->del_work);
1561         }
1562 }
1563 EXPORT_SYMBOL_GPL(l2tp_tunnel_delete);
1564 
1565 /* Really kill the session.
1566  */
1567 void l2tp_session_free(struct l2tp_session *session)
1568 {
1569         struct l2tp_tunnel *tunnel = session->tunnel;
1570 
1571         BUG_ON(refcount_read(&session->ref_count) != 0);
1572 
1573         if (tunnel) {
1574                 BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);
1575                 l2tp_tunnel_dec_refcount(tunnel);
1576         }
1577 
1578         kfree(session);
1579 }
1580 EXPORT_SYMBOL_GPL(l2tp_session_free);
1581 
1582 /* Remove an l2tp session from l2tp_core's hash lists.
1583  * Provides a tidyup interface for pseudowire code which can't just route all
1584  * shutdown via. l2tp_session_delete and a pseudowire-specific session_close
1585  * callback.
1586  */
1587 void __l2tp_session_unhash(struct l2tp_session *session)
1588 {
1589         struct l2tp_tunnel *tunnel = session->tunnel;
1590 
1591         /* Remove the session from core hashes */
1592         if (tunnel) {
1593                 /* Remove from the per-tunnel hash */
1594                 write_lock_bh(&tunnel->hlist_lock);
1595                 hlist_del_init(&session->hlist);
1596                 write_unlock_bh(&tunnel->hlist_lock);
1597 
1598                 /* For L2TPv3 we have a per-net hash: remove from there, too */
1599                 if (tunnel->version != L2TP_HDR_VER_2) {
1600                         struct l2tp_net *pn = l2tp_pernet(tunnel->l2tp_net);
1601                         spin_lock_bh(&pn->l2tp_session_hlist_lock);
1602                         hlist_del_init_rcu(&session->global_hlist);
1603                         spin_unlock_bh(&pn->l2tp_session_hlist_lock);
1604                         synchronize_rcu();
1605                 }
1606         }
1607 }
1608 EXPORT_SYMBOL_GPL(__l2tp_session_unhash);
1609 
1610 /* This function is used by the netlink SESSION_DELETE command and by
1611    pseudowire modules.
1612  */
1613 int l2tp_session_delete(struct l2tp_session *session)
1614 {
1615         if (test_and_set_bit(0, &session->dead))
1616                 return 0;
1617 
1618         __l2tp_session_unhash(session);
1619         l2tp_session_queue_purge(session);
1620         if (session->session_close != NULL)
1621                 (*session->session_close)(session);
1622 
1623         l2tp_session_dec_refcount(session);
1624 
1625         return 0;
1626 }
1627 EXPORT_SYMBOL_GPL(l2tp_session_delete);
1628 
1629 /* We come here whenever a session's send_seq, cookie_len or
1630  * l2specific_type parameters are set.
1631  */
1632 void l2tp_session_set_header_len(struct l2tp_session *session, int version)
1633 {
1634         if (version == L2TP_HDR_VER_2) {
1635                 session->hdr_len = 6;
1636                 if (session->send_seq)
1637                         session->hdr_len += 4;
1638         } else {
1639                 session->hdr_len = 4 + session->cookie_len;
1640                 session->hdr_len += l2tp_get_l2specific_len(session);
1641                 if (session->tunnel->encap == L2TP_ENCAPTYPE_UDP)
1642                         session->hdr_len += 4;
1643         }
1644 
1645 }
1646 EXPORT_SYMBOL_GPL(l2tp_session_set_header_len);
1647 
1648 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)
1649 {
1650         struct l2tp_session *session;
1651 
1652         session = kzalloc(sizeof(struct l2tp_session) + priv_size, GFP_KERNEL);
1653         if (session != NULL) {
1654                 session->magic = L2TP_SESSION_MAGIC;
1655                 session->tunnel = tunnel;
1656 
1657                 session->session_id = session_id;
1658                 session->peer_session_id = peer_session_id;
1659                 session->nr = 0;
1660                 if (tunnel->version == L2TP_HDR_VER_2)
1661                         session->nr_max = 0xffff;
1662                 else
1663                         session->nr_max = 0xffffff;
1664                 session->nr_window_size = session->nr_max / 2;
1665                 session->nr_oos_count_max = 4;
1666 
1667                 /* Use NR of first received packet */
1668                 session->reorder_skip = 1;
1669 
1670                 sprintf(&session->name[0], "sess %u/%u",
1671                         tunnel->tunnel_id, session->session_id);
1672 
1673                 skb_queue_head_init(&session->reorder_q);
1674 
1675                 INIT_HLIST_NODE(&session->hlist);
1676                 INIT_HLIST_NODE(&session->global_hlist);
1677 
1678                 /* Inherit debug options from tunnel */
1679                 session->debug = tunnel->debug;
1680 
1681                 if (cfg) {
1682                         session->pwtype = cfg->pw_type;
1683                         session->debug = cfg->debug;
1684                         session->send_seq = cfg->send_seq;
1685                         session->recv_seq = cfg->recv_seq;
1686                         session->lns_mode = cfg->lns_mode;
1687                         session->reorder_timeout = cfg->reorder_timeout;
1688                         session->l2specific_type = cfg->l2specific_type;
1689                         session->cookie_len = cfg->cookie_len;
1690                         memcpy(&session->cookie[0], &cfg->cookie[0], cfg->cookie_len);
1691                         session->peer_cookie_len = cfg->peer_cookie_len;
1692                         memcpy(&session->peer_cookie[0], &cfg->peer_cookie[0], cfg->peer_cookie_len);
1693                 }
1694 
1695                 if (tunnel->version == L2TP_HDR_VER_2)
1696                         session->build_header = l2tp_build_l2tpv2_header;
1697                 else
1698                         session->build_header = l2tp_build_l2tpv3_header;
1699 
1700                 l2tp_session_set_header_len(session, tunnel->version);
1701 
1702                 refcount_set(&session->ref_count, 1);
1703 
1704                 return session;
1705         }
1706 
1707         return ERR_PTR(-ENOMEM);
1708 }
1709 EXPORT_SYMBOL_GPL(l2tp_session_create);
1710 
1711 /*****************************************************************************
1712  * Init and cleanup
1713  *****************************************************************************/
1714 
1715 static __net_init int l2tp_init_net(struct net *net)
1716 {
1717         struct l2tp_net *pn = net_generic(net, l2tp_net_id);
1718         int hash;
1719 
1720         INIT_LIST_HEAD(&pn->l2tp_tunnel_list);
1721         spin_lock_init(&pn->l2tp_tunnel_list_lock);
1722 
1723         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1724                 INIT_HLIST_HEAD(&pn->l2tp_session_hlist[hash]);
1725 
1726         spin_lock_init(&pn->l2tp_session_hlist_lock);
1727 
1728         return 0;
1729 }
1730 
1731 static __net_exit void l2tp_exit_net(struct net *net)
1732 {
1733         struct l2tp_net *pn = l2tp_pernet(net);
1734         struct l2tp_tunnel *tunnel = NULL;
1735         int hash;
1736 
1737         rcu_read_lock_bh();
1738         list_for_each_entry_rcu(tunnel, &pn->l2tp_tunnel_list, list) {
1739                 l2tp_tunnel_delete(tunnel);
1740         }
1741         rcu_read_unlock_bh();
1742 
1743         if (l2tp_wq)
1744                 flush_workqueue(l2tp_wq);
1745         rcu_barrier();
1746 
1747         for (hash = 0; hash < L2TP_HASH_SIZE_2; hash++)
1748                 WARN_ON_ONCE(!hlist_empty(&pn->l2tp_session_hlist[hash]));
1749 }
1750 
1751 static struct pernet_operations l2tp_net_ops = {
1752         .init = l2tp_init_net,
1753         .exit = l2tp_exit_net,
1754         .id   = &l2tp_net_id,
1755         .size = sizeof(struct l2tp_net),
1756 };
1757 
1758 static int __init l2tp_init(void)
1759 {
1760         int rc = 0;
1761 
1762         rc = register_pernet_device(&l2tp_net_ops);
1763         if (rc)
1764                 goto out;
1765 
1766         l2tp_wq = alloc_workqueue("l2tp", WQ_UNBOUND, 0);
1767         if (!l2tp_wq) {
1768                 pr_err("alloc_workqueue failed\n");
1769                 unregister_pernet_device(&l2tp_net_ops);
1770                 rc = -ENOMEM;
1771                 goto out;
1772         }
1773 
1774         pr_info("L2TP core driver, %s\n", L2TP_DRV_VERSION);
1775 
1776 out:
1777         return rc;
1778 }
1779 
1780 static void __exit l2tp_exit(void)
1781 {
1782         unregister_pernet_device(&l2tp_net_ops);
1783         if (l2tp_wq) {
1784                 destroy_workqueue(l2tp_wq);
1785                 l2tp_wq = NULL;
1786         }
1787 }
1788 
1789 module_init(l2tp_init);
1790 module_exit(l2tp_exit);
1791 
1792 MODULE_AUTHOR("James Chapman <jchapman@katalix.com>");
1793 MODULE_DESCRIPTION("L2TP core");
1794 MODULE_LICENSE("GPL");
1795 MODULE_VERSION(L2TP_DRV_VERSION);
/* [<][>][^][v][top][bottom][index][help] */
root/net/l2tp/l2tp_core.c

DEFINITIONS
