net/tipc/server.c

   1 /*
   2  * net/tipc/server.c: TIPC server infrastructure
   3  *
   4  * Copyright (c) 2012-2013, Wind River Systems
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  * 2. Redistributions in binary form must reproduce the above copyright
  13  *    notice, this list of conditions and the following disclaimer in the
  14  *    documentation and/or other materials provided with the distribution.
  15  * 3. Neither the names of the copyright holders nor the names of its
  16  *    contributors may be used to endorse or promote products derived from
  17  *    this software without specific prior written permission.
  18  *
  19  * Alternatively, this software may be distributed under the terms of the
  20  * GNU General Public License ("GPL") version 2 as published by the Free
  21  * Software Foundation.
  22  *
  23  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  24  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  25  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  26  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  27  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  28  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  29  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  30  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  31  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  32  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  33  * POSSIBILITY OF SUCH DAMAGE.
  34  */
  35
  36 #include "server.h"
  37 #include "core.h"
  38 #include "socket.h"
  39 #include <net/sock.h>
  40 #include <linux/module.h>
  41
  42 /* Number of messages to send before rescheduling */
  43 #define MAX_SEND_MSG_COUNT      25
  44 #define MAX_RECV_MSG_COUNT      25
  45 #define CF_CONNECTED            1
  46 #define CF_SERVER               2
  47
  48 #define sock2con(x) ((struct tipc_conn *)(x)->sk_user_data)
  49
  50 /**
  51  * struct tipc_conn - TIPC connection structure
  52  * @kref: reference counter to connection object
  53  * @conid: connection identifier
  54  * @sock: socket handler associated with connection
  55  * @flags: indicates connection state
  56  * @server: pointer to connected server
  57  * @rwork: receive work item
  58  * @usr_data: user-specified field
  59  * @rx_action: what to do when connection socket is active
  60  * @outqueue: pointer to first outbound message in queue
  61  * @outqueue_lock: control access to the outqueue
  62  * @outqueue: list of connection objects for its server
  63  * @swork: send work item
  64  */
  65 struct tipc_conn {
  66         struct kref kref;
  67         int conid;
  68         struct socket *sock;
  69         unsigned long flags;
  70         struct tipc_server *server;
  71         struct work_struct rwork;
  72         int (*rx_action) (struct tipc_conn *con);
  73         void *usr_data;
  74         struct list_head outqueue;
  75         spinlock_t outqueue_lock;
  76         struct work_struct swork;
  77 };
  78
  79 /* An entry waiting to be sent */
  80 struct outqueue_entry {
  81         struct list_head list;
  82         struct kvec iov;
  83         struct sockaddr_tipc dest;
  84 };
  85
  86 static void tipc_recv_work(struct work_struct *work);
  87 static void tipc_send_work(struct work_struct *work);
  88 static void tipc_clean_outqueues(struct tipc_conn *con);
  89
  90 static void tipc_conn_kref_release(struct kref *kref)
  91 {
  92         struct tipc_conn *con = container_of(kref, struct tipc_conn, kref);
  93         struct tipc_server *s = con->server;
  94         struct sockaddr_tipc *saddr = s->saddr;
  95         struct socket *sock = con->sock;
  96         struct sock *sk;
  97
  98         if (sock) {
  99                 sk = sock->sk;
 100                 if (test_bit(CF_SERVER, &con->flags)) {
 101                         __module_get(sock->ops->owner);
 102                         __module_get(sk->sk_prot_creator->owner);
 103                 }
 104                 saddr->scope = -TIPC_NODE_SCOPE;
 105                 kernel_bind(sock, (struct sockaddr *)saddr, sizeof(*saddr));
 106                 sock_release(sock);
 107                 con->sock = NULL;
 108
 109                 spin_lock_bh(&s->idr_lock);
 110                 idr_remove(&s->conn_idr, con->conid);
 111                 s->idr_in_use--;
 112                 spin_unlock_bh(&s->idr_lock);
 113         }
 114
 115         tipc_clean_outqueues(con);
 116         kfree(con);
 117 }
 118
 119 static void conn_put(struct tipc_conn *con)
 120 {
 121         kref_put(&con->kref, tipc_conn_kref_release);
 122 }
 123
 124 static void conn_get(struct tipc_conn *con)
 125 {
 126         kref_get(&con->kref);
 127 }
 128
 129 static struct tipc_conn *tipc_conn_lookup(struct tipc_server *s, int conid)
 130 {
 131         struct tipc_conn *con;
 132
 133         spin_lock_bh(&s->idr_lock);
 134         con = idr_find(&s->conn_idr, conid);
 135         if (con && test_bit(CF_CONNECTED, &con->flags))
 136                 conn_get(con);
 137         else
 138                 con = NULL;
 139         spin_unlock_bh(&s->idr_lock);
 140         return con;
 141 }
 142
 143 static void sock_data_ready(struct sock *sk)
 144 {
 145         struct tipc_conn *con;
 146
 147         read_lock_bh(&sk->sk_callback_lock);
 148         con = sock2con(sk);
 149         if (con && test_bit(CF_CONNECTED, &con->flags)) {
 150                 conn_get(con);
 151                 if (!queue_work(con->server->rcv_wq, &con->rwork))
 152                         conn_put(con);
 153         }
 154         read_unlock_bh(&sk->sk_callback_lock);
 155 }
 156
 157 static void sock_write_space(struct sock *sk)
 158 {
 159         struct tipc_conn *con;
 160
 161         read_lock_bh(&sk->sk_callback_lock);
 162         con = sock2con(sk);
 163         if (con && test_bit(CF_CONNECTED, &con->flags)) {
 164                 conn_get(con);
 165                 if (!queue_work(con->server->send_wq, &con->swork))
 166                         conn_put(con);
 167         }
 168         read_unlock_bh(&sk->sk_callback_lock);
 169 }
 170
 171 static void tipc_register_callbacks(struct socket *sock, struct tipc_conn *con)
 172 {
 173         struct sock *sk = sock->sk;
 174
 175         write_lock_bh(&sk->sk_callback_lock);
 176
 177         sk->sk_data_ready = sock_data_ready;
 178         sk->sk_write_space = sock_write_space;
 179         sk->sk_user_data = con;
 180
 181         con->sock = sock;
 182
 183         write_unlock_bh(&sk->sk_callback_lock);
 184 }
 185
 186 static void tipc_unregister_callbacks(struct tipc_conn *con)
 187 {
 188         struct sock *sk = con->sock->sk;
 189
 190         write_lock_bh(&sk->sk_callback_lock);
 191         sk->sk_user_data = NULL;
 192         write_unlock_bh(&sk->sk_callback_lock);
 193 }
 194
 195 static void tipc_close_conn(struct tipc_conn *con)
 196 {
 197         struct tipc_server *s = con->server;
 198
 199         if (test_and_clear_bit(CF_CONNECTED, &con->flags)) {
 200                 tipc_unregister_callbacks(con);
 201
 202                 if (con->conid)
 203                         s->tipc_conn_release(con->conid, con->usr_data);
 204
 205                 /* We shouldn't flush pending works as we may be in the
 206                  * thread. In fact the races with pending rx/tx work structs
 207                  * are harmless for us here as we have already deleted this
 208                  * connection from server connection list.
 209                  */
 210                 kernel_sock_shutdown(con->sock, SHUT_RDWR);
 211
 212                 conn_put(con);
 213         }
 214 }
 215
 216 static struct tipc_conn *tipc_alloc_conn(struct tipc_server *s)
 217 {
 218         struct tipc_conn *con;
 219         int ret;
 220
 221         con = kzalloc(sizeof(struct tipc_conn), GFP_ATOMIC);
 222         if (!con)
 223                 return ERR_PTR(-ENOMEM);
 224
 225         kref_init(&con->kref);
 226         INIT_LIST_HEAD(&con->outqueue);
 227         spin_lock_init(&con->outqueue_lock);
 228         INIT_WORK(&con->swork, tipc_send_work);
 229         INIT_WORK(&con->rwork, tipc_recv_work);
 230
 231         spin_lock_bh(&s->idr_lock);
 232         ret = idr_alloc(&s->conn_idr, con, 0, 0, GFP_ATOMIC);
 233         if (ret < 0) {
 234                 kfree(con);
 235                 spin_unlock_bh(&s->idr_lock);
 236                 return ERR_PTR(-ENOMEM);
 237         }
 238         con->conid = ret;
 239         s->idr_in_use++;
 240         spin_unlock_bh(&s->idr_lock);
 241
 242         set_bit(CF_CONNECTED, &con->flags);
 243         con->server = s;
 244
 245         return con;
 246 }
 247
 248 static int tipc_receive_from_sock(struct tipc_conn *con)
 249 {
 250         struct msghdr msg = {};
 251         struct tipc_server *s = con->server;
 252         struct sockaddr_tipc addr;
 253         struct kvec iov;
 254         void *buf;
 255         int ret;
 256
 257         buf = kmem_cache_alloc(s->rcvbuf_cache, GFP_ATOMIC);
 258         if (!buf) {
 259                 ret = -ENOMEM;
 260                 goto out_close;
 261         }
 262
 263         iov.iov_base = buf;
 264         iov.iov_len = s->max_rcvbuf_size;
 265         msg.msg_name = &addr;
 266         ret = kernel_recvmsg(con->sock, &msg, &iov, 1, iov.iov_len,
 267                              MSG_DONTWAIT);
 268         if (ret <= 0) {
 269                 kmem_cache_free(s->rcvbuf_cache, buf);
 270                 goto out_close;
 271         }
 272
 273         s->tipc_conn_recvmsg(sock_net(con->sock->sk), con->conid, &addr,
 274                              con->usr_data, buf, ret);
 275
 276         kmem_cache_free(s->rcvbuf_cache, buf);
 277
 278         return 0;
 279
 280 out_close:
 281         if (ret != -EWOULDBLOCK)
 282                 tipc_close_conn(con);
 283         else if (ret == 0)
 284                 /* Don't return success if we really got EOF */
 285                 ret = -EAGAIN;
 286
 287         return ret;
 288 }
 289
 290 static int tipc_accept_from_sock(struct tipc_conn *con)
 291 {
 292         struct tipc_server *s = con->server;
 293         struct socket *sock = con->sock;
 294         struct socket *newsock;
 295         struct tipc_conn *newcon;
 296         int ret;
 297
 298         ret = kernel_accept(sock, &newsock, O_NONBLOCK);
 299         if (ret < 0)
 300                 return ret;
 301
 302         newcon = tipc_alloc_conn(con->server);
 303         if (IS_ERR(newcon)) {
 304                 ret = PTR_ERR(newcon);
 305                 sock_release(newsock);
 306                 return ret;
 307         }
 308
 309         newcon->rx_action = tipc_receive_from_sock;
 310         tipc_register_callbacks(newsock, newcon);
 311
 312         /* Notify that new connection is incoming */
 313         newcon->usr_data = s->tipc_conn_new(newcon->conid);
 314         if (!newcon->usr_data) {
 315                 sock_release(newsock);
 316                 conn_put(newcon);
 317                 return -ENOMEM;
 318         }
 319
 320         /* Wake up receive process in case of 'SYN+' message */
 321         newsock->sk->sk_data_ready(newsock->sk);
 322         return ret;
 323 }
 324
 325 static struct socket *tipc_create_listen_sock(struct tipc_conn *con)
 326 {
 327         struct tipc_server *s = con->server;
 328         struct socket *sock = NULL;
 329         int ret;
 330
 331         ret = sock_create_kern(s->net, AF_TIPC, SOCK_SEQPACKET, 0, &sock);
 332         if (ret < 0)
 333                 return NULL;
 334         ret = kernel_setsockopt(sock, SOL_TIPC, TIPC_IMPORTANCE,
 335                                 (char *)&s->imp, sizeof(s->imp));
 336         if (ret < 0)
 337                 goto create_err;
 338         ret = kernel_bind(sock, (struct sockaddr *)s->saddr, sizeof(*s->saddr));
 339         if (ret < 0)
 340                 goto create_err;
 341
 342         switch (s->type) {
 343         case SOCK_STREAM:
 344         case SOCK_SEQPACKET:
 345                 con->rx_action = tipc_accept_from_sock;
 346
 347                 ret = kernel_listen(sock, 0);
 348                 if (ret < 0)
 349                         goto create_err;
 350                 break;
 351         case SOCK_DGRAM:
 352         case SOCK_RDM:
 353                 con->rx_action = tipc_receive_from_sock;
 354                 break;
 355         default:
 356                 pr_err("Unknown socket type %d\n", s->type);
 357                 goto create_err;
 358         }
 359
 360         /* As server's listening socket owner and creator is the same module,
 361          * we have to decrease TIPC module reference count to guarantee that
 362          * it remains zero after the server socket is created, otherwise,
 363          * executing "rmmod" command is unable to make TIPC module deleted
 364          * after TIPC module is inserted successfully.
 365          *
 366          * However, the reference count is ever increased twice in
 367          * sock_create_kern(): one is to increase the reference count of owner
 368          * of TIPC socket's proto_ops struct; another is to increment the
 369          * reference count of owner of TIPC proto struct. Therefore, we must
 370          * decrement the module reference count twice to ensure that it keeps
 371          * zero after server's listening socket is created. Of course, we
 372          * must bump the module reference count twice as well before the socket
 373          * is closed.
 374          */
 375         module_put(sock->ops->owner);
 376         module_put(sock->sk->sk_prot_creator->owner);
 377         set_bit(CF_SERVER, &con->flags);
 378
 379         return sock;
 380
 381 create_err:
 382         kernel_sock_shutdown(sock, SHUT_RDWR);
 383         sock_release(sock);
 384         return NULL;
 385 }
 386
 387 static int tipc_open_listening_sock(struct tipc_server *s)
 388 {
 389         struct socket *sock;
 390         struct tipc_conn *con;
 391
 392         con = tipc_alloc_conn(s);
 393         if (IS_ERR(con))
 394                 return PTR_ERR(con);
 395
 396         sock = tipc_create_listen_sock(con);
 397         if (!sock) {
 398                 idr_remove(&s->conn_idr, con->conid);
 399                 s->idr_in_use--;
 400                 kfree(con);
 401                 return -EINVAL;
 402         }
 403
 404         tipc_register_callbacks(sock, con);
 405         return 0;
 406 }
 407
 408 static struct outqueue_entry *tipc_alloc_entry(void *data, int len)
 409 {
 410         struct outqueue_entry *entry;
 411         void *buf;
 412
 413         entry = kmalloc(sizeof(struct outqueue_entry), GFP_ATOMIC);
 414         if (!entry)
 415                 return NULL;
 416
 417         buf = kmemdup(data, len, GFP_ATOMIC);
 418         if (!buf) {
 419                 kfree(entry);
 420                 return NULL;
 421         }
 422
 423         entry->iov.iov_base = buf;
 424         entry->iov.iov_len = len;
 425
 426         return entry;
 427 }
 428
 429 static void tipc_free_entry(struct outqueue_entry *e)
 430 {
 431         kfree(e->iov.iov_base);
 432         kfree(e);
 433 }
 434
 435 static void tipc_clean_outqueues(struct tipc_conn *con)
 436 {
 437         struct outqueue_entry *e, *safe;
 438
 439         spin_lock_bh(&con->outqueue_lock);
 440         list_for_each_entry_safe(e, safe, &con->outqueue, list) {
 441                 list_del(&e->list);
 442                 tipc_free_entry(e);
 443         }
 444         spin_unlock_bh(&con->outqueue_lock);
 445 }
 446
 447 int tipc_conn_sendmsg(struct tipc_server *s, int conid,
 448                       struct sockaddr_tipc *addr, void *data, size_t len)
 449 {
 450         struct outqueue_entry *e;
 451         struct tipc_conn *con;
 452
 453         con = tipc_conn_lookup(s, conid);
 454         if (!con)
 455                 return -EINVAL;
 456
 457         if (!test_bit(CF_CONNECTED, &con->flags)) {
 458                 conn_put(con);
 459                 return 0;
 460         }
 461
 462         e = tipc_alloc_entry(data, len);
 463         if (!e) {
 464                 conn_put(con);
 465                 return -ENOMEM;
 466         }
 467
 468         if (addr)
 469                 memcpy(&e->dest, addr, sizeof(struct sockaddr_tipc));
 470
 471         spin_lock_bh(&con->outqueue_lock);
 472         list_add_tail(&e->list, &con->outqueue);
 473         spin_unlock_bh(&con->outqueue_lock);
 474
 475         if (!queue_work(s->send_wq, &con->swork))
 476                 conn_put(con);
 477         return 0;
 478 }
 479
 480 void tipc_conn_terminate(struct tipc_server *s, int conid)
 481 {
 482         struct tipc_conn *con;
 483
 484         con = tipc_conn_lookup(s, conid);
 485         if (con) {
 486                 tipc_close_conn(con);
 487                 conn_put(con);
 488         }
 489 }
 490
 491 static void tipc_send_to_sock(struct tipc_conn *con)
 492 {
 493         int count = 0;
 494         struct tipc_server *s = con->server;
 495         struct outqueue_entry *e;
 496         struct msghdr msg;
 497         int ret;
 498
 499         spin_lock_bh(&con->outqueue_lock);
 500         while (test_bit(CF_CONNECTED, &con->flags)) {
 501                 e = list_entry(con->outqueue.next, struct outqueue_entry,
 502                                list);
 503                 if ((struct list_head *) e == &con->outqueue)
 504                         break;
 505                 spin_unlock_bh(&con->outqueue_lock);
 506
 507                 memset(&msg, 0, sizeof(msg));
 508                 msg.msg_flags = MSG_DONTWAIT;
 509
 510                 if (s->type == SOCK_DGRAM || s->type == SOCK_RDM) {
 511                         msg.msg_name = &e->dest;
 512                         msg.msg_namelen = sizeof(struct sockaddr_tipc);
 513                 }
 514                 ret = kernel_sendmsg(con->sock, &msg, &e->iov, 1,
 515                                      e->iov.iov_len);
 516                 if (ret == -EWOULDBLOCK || ret == 0) {
 517                         cond_resched();
 518                         goto out;
 519                 } else if (ret < 0) {
 520                         goto send_err;
 521                 }
 522
 523                 /* Don't starve users filling buffers */
 524                 if (++count >= MAX_SEND_MSG_COUNT) {
 525                         cond_resched();
 526                         count = 0;
 527                 }
 528
 529                 spin_lock_bh(&con->outqueue_lock);
 530                 list_del(&e->list);
 531                 tipc_free_entry(e);
 532         }
 533         spin_unlock_bh(&con->outqueue_lock);
 534 out:
 535         return;
 536
 537 send_err:
 538         tipc_close_conn(con);
 539 }
 540
 541 static void tipc_recv_work(struct work_struct *work)
 542 {
 543         struct tipc_conn *con = container_of(work, struct tipc_conn, rwork);
 544         int count = 0;
 545
 546         while (test_bit(CF_CONNECTED, &con->flags)) {
 547                 if (con->rx_action(con))
 548                         break;
 549
 550                 /* Don't flood Rx machine */
 551                 if (++count >= MAX_RECV_MSG_COUNT) {
 552                         cond_resched();
 553                         count = 0;
 554                 }
 555         }
 556         conn_put(con);
 557 }
 558
 559 static void tipc_send_work(struct work_struct *work)
 560 {
 561         struct tipc_conn *con = container_of(work, struct tipc_conn, swork);
 562
 563         if (test_bit(CF_CONNECTED, &con->flags))
 564                 tipc_send_to_sock(con);
 565
 566         conn_put(con);
 567 }
 568
 569 static void tipc_work_stop(struct tipc_server *s)
 570 {
 571         destroy_workqueue(s->rcv_wq);
 572         destroy_workqueue(s->send_wq);
 573 }
 574
 575 static int tipc_work_start(struct tipc_server *s)
 576 {
 577         s->rcv_wq = alloc_ordered_workqueue("tipc_rcv", 0);
 578         if (!s->rcv_wq) {
 579                 pr_err("can't start tipc receive workqueue\n");
 580                 return -ENOMEM;
 581         }
 582
 583         s->send_wq = alloc_ordered_workqueue("tipc_send", 0);
 584         if (!s->send_wq) {
 585                 pr_err("can't start tipc send workqueue\n");
 586                 destroy_workqueue(s->rcv_wq);
 587                 return -ENOMEM;
 588         }
 589
 590         return 0;
 591 }
 592
 593 int tipc_server_start(struct tipc_server *s)
 594 {
 595         int ret;
 596
 597         spin_lock_init(&s->idr_lock);
 598         idr_init(&s->conn_idr);
 599         s->idr_in_use = 0;
 600
 601         s->rcvbuf_cache = kmem_cache_create(s->name, s->max_rcvbuf_size,
 602                                             0, SLAB_HWCACHE_ALIGN, NULL);
 603         if (!s->rcvbuf_cache)
 604                 return -ENOMEM;
 605
 606         ret = tipc_work_start(s);
 607         if (ret < 0) {
 608                 kmem_cache_destroy(s->rcvbuf_cache);
 609                 return ret;
 610         }
 611         ret = tipc_open_listening_sock(s);
 612         if (ret < 0) {
 613                 tipc_work_stop(s);
 614                 kmem_cache_destroy(s->rcvbuf_cache);
 615                 return ret;
 616         }
 617         return ret;
 618 }
 619
 620 void tipc_server_stop(struct tipc_server *s)
 621 {
 622         struct tipc_conn *con;
 623         int id;
 624
 625         spin_lock_bh(&s->idr_lock);
 626         for (id = 0; s->idr_in_use; id++) {
 627                 con = idr_find(&s->conn_idr, id);
 628                 if (con) {
 629                         spin_unlock_bh(&s->idr_lock);
 630                         tipc_close_conn(con);
 631                         spin_lock_bh(&s->idr_lock);
 632                 }
 633         }
 634         spin_unlock_bh(&s->idr_lock);
 635
 636         tipc_work_stop(s);
 637         kmem_cache_destroy(s->rcvbuf_cache);
 638         idr_destroy(&s->conn_idr);
 639 }