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 sockaddr_tipc *saddr = con->server->saddr;
  94         struct socket *sock = con->sock;
  95         struct sock *sk;
  96
  97         if (sock) {
  98                 sk = sock->sk;
  99                 if (test_bit(CF_SERVER, &con->flags)) {
 100                         __module_get(sock->ops->owner);
 101                         __module_get(sk->sk_prot_creator->owner);
 102                 }
 103                 saddr->scope = -TIPC_NODE_SCOPE;
 104                 kernel_bind(sock, (struct sockaddr *)saddr, sizeof(*saddr));
 105                 sock_release(sock);
 106                 con->sock = NULL;
 107         }
 108
 109         tipc_clean_outqueues(con);
 110         kfree(con);
 111 }
 112
 113 static void conn_put(struct tipc_conn *con)
 114 {
 115         kref_put(&con->kref, tipc_conn_kref_release);
 116 }
 117
 118 static void conn_get(struct tipc_conn *con)
 119 {
 120         kref_get(&con->kref);
 121 }
 122
 123 static struct tipc_conn *tipc_conn_lookup(struct tipc_server *s, int conid)
 124 {
 125         struct tipc_conn *con;
 126
 127         spin_lock_bh(&s->idr_lock);
 128         con = idr_find(&s->conn_idr, conid);
 129         if (con)
 130                 conn_get(con);
 131         spin_unlock_bh(&s->idr_lock);
 132         return con;
 133 }
 134
 135 static void sock_data_ready(struct sock *sk)
 136 {
 137         struct tipc_conn *con;
 138
 139         read_lock(&sk->sk_callback_lock);
 140         con = sock2con(sk);
 141         if (con && test_bit(CF_CONNECTED, &con->flags)) {
 142                 conn_get(con);
 143                 if (!queue_work(con->server->rcv_wq, &con->rwork))
 144                         conn_put(con);
 145         }
 146         read_unlock(&sk->sk_callback_lock);
 147 }
 148
 149 static void sock_write_space(struct sock *sk)
 150 {
 151         struct tipc_conn *con;
 152
 153         read_lock(&sk->sk_callback_lock);
 154         con = sock2con(sk);
 155         if (con && test_bit(CF_CONNECTED, &con->flags)) {
 156                 conn_get(con);
 157                 if (!queue_work(con->server->send_wq, &con->swork))
 158                         conn_put(con);
 159         }
 160         read_unlock(&sk->sk_callback_lock);
 161 }
 162
 163 static void tipc_register_callbacks(struct socket *sock, struct tipc_conn *con)
 164 {
 165         struct sock *sk = sock->sk;
 166
 167         write_lock_bh(&sk->sk_callback_lock);
 168
 169         sk->sk_data_ready = sock_data_ready;
 170         sk->sk_write_space = sock_write_space;
 171         sk->sk_user_data = con;
 172
 173         con->sock = sock;
 174
 175         write_unlock_bh(&sk->sk_callback_lock);
 176 }
 177
 178 static void tipc_unregister_callbacks(struct tipc_conn *con)
 179 {
 180         struct sock *sk = con->sock->sk;
 181
 182         write_lock_bh(&sk->sk_callback_lock);
 183         sk->sk_user_data = NULL;
 184         write_unlock_bh(&sk->sk_callback_lock);
 185 }
 186
 187 static void tipc_close_conn(struct tipc_conn *con)
 188 {
 189         struct tipc_server *s = con->server;
 190
 191         if (test_and_clear_bit(CF_CONNECTED, &con->flags)) {
 192                 if (con->conid)
 193                         s->tipc_conn_shutdown(con->conid, con->usr_data);
 194
 195                 spin_lock_bh(&s->idr_lock);
 196                 idr_remove(&s->conn_idr, con->conid);
 197                 s->idr_in_use--;
 198                 spin_unlock_bh(&s->idr_lock);
 199
 200                 tipc_unregister_callbacks(con);
 201
 202                 /* We shouldn't flush pending works as we may be in the
 203                  * thread. In fact the races with pending rx/tx work structs
 204                  * are harmless for us here as we have already deleted this
 205                  * connection from server connection list and set
 206                  * sk->sk_user_data to 0 before releasing connection object.
 207                  */
 208                 kernel_sock_shutdown(con->sock, SHUT_RDWR);
 209
 210                 conn_put(con);
 211         }
 212 }
 213
 214 static struct tipc_conn *tipc_alloc_conn(struct tipc_server *s)
 215 {
 216         struct tipc_conn *con;
 217         int ret;
 218
 219         con = kzalloc(sizeof(struct tipc_conn), GFP_ATOMIC);
 220         if (!con)
 221                 return ERR_PTR(-ENOMEM);
 222
 223         kref_init(&con->kref);
 224         INIT_LIST_HEAD(&con->outqueue);
 225         spin_lock_init(&con->outqueue_lock);
 226         INIT_WORK(&con->swork, tipc_send_work);
 227         INIT_WORK(&con->rwork, tipc_recv_work);
 228
 229         spin_lock_bh(&s->idr_lock);
 230         ret = idr_alloc(&s->conn_idr, con, 0, 0, GFP_ATOMIC);
 231         if (ret < 0) {
 232                 kfree(con);
 233                 spin_unlock_bh(&s->idr_lock);
 234                 return ERR_PTR(-ENOMEM);
 235         }
 236         con->conid = ret;
 237         s->idr_in_use++;
 238         spin_unlock_bh(&s->idr_lock);
 239
 240         set_bit(CF_CONNECTED, &con->flags);
 241         con->server = s;
 242
 243         return con;
 244 }
 245
 246 static int tipc_receive_from_sock(struct tipc_conn *con)
 247 {
 248         struct msghdr msg = {};
 249         struct tipc_server *s = con->server;
 250         struct sockaddr_tipc addr;
 251         struct kvec iov;
 252         void *buf;
 253         int ret;
 254
 255         buf = kmem_cache_alloc(s->rcvbuf_cache, GFP_ATOMIC);
 256         if (!buf) {
 257                 ret = -ENOMEM;
 258                 goto out_close;
 259         }
 260
 261         iov.iov_base = buf;
 262         iov.iov_len = s->max_rcvbuf_size;
 263         msg.msg_name = &addr;
 264         ret = kernel_recvmsg(con->sock, &msg, &iov, 1, iov.iov_len,
 265                              MSG_DONTWAIT);
 266         if (ret <= 0) {
 267                 kmem_cache_free(s->rcvbuf_cache, buf);
 268                 goto out_close;
 269         }
 270
 271         s->tipc_conn_recvmsg(sock_net(con->sock->sk), con->conid, &addr,
 272                              con->usr_data, buf, ret);
 273
 274         kmem_cache_free(s->rcvbuf_cache, buf);
 275
 276         return 0;
 277
 278 out_close:
 279         if (ret != -EWOULDBLOCK)
 280                 tipc_close_conn(con);
 281         else if (ret == 0)
 282                 /* Don't return success if we really got EOF */
 283                 ret = -EAGAIN;
 284
 285         return ret;
 286 }
 287
 288 static int tipc_accept_from_sock(struct tipc_conn *con)
 289 {
 290         struct tipc_server *s = con->server;
 291         struct socket *sock = con->sock;
 292         struct socket *newsock;
 293         struct tipc_conn *newcon;
 294         int ret;
 295
 296         ret = kernel_accept(sock, &newsock, O_NONBLOCK);
 297         if (ret < 0)
 298                 return ret;
 299
 300         newcon = tipc_alloc_conn(con->server);
 301         if (IS_ERR(newcon)) {
 302                 ret = PTR_ERR(newcon);
 303                 sock_release(newsock);
 304                 return ret;
 305         }
 306
 307         newcon->rx_action = tipc_receive_from_sock;
 308         tipc_register_callbacks(newsock, newcon);
 309
 310         /* Notify that new connection is incoming */
 311         newcon->usr_data = s->tipc_conn_new(newcon->conid);
 312         if (!newcon->usr_data) {
 313                 sock_release(newsock);
 314                 conn_put(newcon);
 315                 return -ENOMEM;
 316         }
 317
 318         /* Wake up receive process in case of 'SYN+' message */
 319         newsock->sk->sk_data_ready(newsock->sk);
 320         return ret;
 321 }
 322
 323 static struct socket *tipc_create_listen_sock(struct tipc_conn *con)
 324 {
 325         struct tipc_server *s = con->server;
 326         struct socket *sock = NULL;
 327         int ret;
 328
 329         ret = sock_create_kern(s->net, AF_TIPC, SOCK_SEQPACKET, 0, &sock);
 330         if (ret < 0)
 331                 return NULL;
 332         ret = kernel_setsockopt(sock, SOL_TIPC, TIPC_IMPORTANCE,
 333                                 (char *)&s->imp, sizeof(s->imp));
 334         if (ret < 0)
 335                 goto create_err;
 336         ret = kernel_bind(sock, (struct sockaddr *)s->saddr, sizeof(*s->saddr));
 337         if (ret < 0)
 338                 goto create_err;
 339
 340         switch (s->type) {
 341         case SOCK_STREAM:
 342         case SOCK_SEQPACKET:
 343                 con->rx_action = tipc_accept_from_sock;
 344
 345                 ret = kernel_listen(sock, 0);
 346                 if (ret < 0)
 347                         goto create_err;
 348                 break;
 349         case SOCK_DGRAM:
 350         case SOCK_RDM:
 351                 con->rx_action = tipc_receive_from_sock;
 352                 break;
 353         default:
 354                 pr_err("Unknown socket type %d\n", s->type);
 355                 goto create_err;
 356         }
 357
 358         /* As server's listening socket owner and creator is the same module,
 359          * we have to decrease TIPC module reference count to guarantee that
 360          * it remains zero after the server socket is created, otherwise,
 361          * executing "rmmod" command is unable to make TIPC module deleted
 362          * after TIPC module is inserted successfully.
 363          *
 364          * However, the reference count is ever increased twice in
 365          * sock_create_kern(): one is to increase the reference count of owner
 366          * of TIPC socket's proto_ops struct; another is to increment the
 367          * reference count of owner of TIPC proto struct. Therefore, we must
 368          * decrement the module reference count twice to ensure that it keeps
 369          * zero after server's listening socket is created. Of course, we
 370          * must bump the module reference count twice as well before the socket
 371          * is closed.
 372          */
 373         module_put(sock->ops->owner);
 374         module_put(sock->sk->sk_prot_creator->owner);
 375         set_bit(CF_SERVER, &con->flags);
 376
 377         return sock;
 378
 379 create_err:
 380         kernel_sock_shutdown(sock, SHUT_RDWR);
 381         sock_release(sock);
 382         return NULL;
 383 }
 384
 385 static int tipc_open_listening_sock(struct tipc_server *s)
 386 {
 387         struct socket *sock;
 388         struct tipc_conn *con;
 389
 390         con = tipc_alloc_conn(s);
 391         if (IS_ERR(con))
 392                 return PTR_ERR(con);
 393
 394         sock = tipc_create_listen_sock(con);
 395         if (!sock) {
 396                 idr_remove(&s->conn_idr, con->conid);
 397                 s->idr_in_use--;
 398                 kfree(con);
 399                 return -EINVAL;
 400         }
 401
 402         tipc_register_callbacks(sock, con);
 403         return 0;
 404 }
 405
 406 static struct outqueue_entry *tipc_alloc_entry(void *data, int len)
 407 {
 408         struct outqueue_entry *entry;
 409         void *buf;
 410
 411         entry = kmalloc(sizeof(struct outqueue_entry), GFP_ATOMIC);
 412         if (!entry)
 413                 return NULL;
 414
 415         buf = kmalloc(len, GFP_ATOMIC);
 416         if (!buf) {
 417                 kfree(entry);
 418                 return NULL;
 419         }
 420
 421         memcpy(buf, data, len);
 422         entry->iov.iov_base = buf;
 423         entry->iov.iov_len = len;
 424
 425         return entry;
 426 }
 427
 428 static void tipc_free_entry(struct outqueue_entry *e)
 429 {
 430         kfree(e->iov.iov_base);
 431         kfree(e);
 432 }
 433
 434 static void tipc_clean_outqueues(struct tipc_conn *con)
 435 {
 436         struct outqueue_entry *e, *safe;
 437
 438         spin_lock_bh(&con->outqueue_lock);
 439         list_for_each_entry_safe(e, safe, &con->outqueue, list) {
 440                 list_del(&e->list);
 441                 tipc_free_entry(e);
 442         }
 443         spin_unlock_bh(&con->outqueue_lock);
 444 }
 445
 446 int tipc_conn_sendmsg(struct tipc_server *s, int conid,
 447                       struct sockaddr_tipc *addr, void *data, size_t len)
 448 {
 449         struct outqueue_entry *e;
 450         struct tipc_conn *con;
 451
 452         con = tipc_conn_lookup(s, conid);
 453         if (!con)
 454                 return -EINVAL;
 455
 456         if (!test_bit(CF_CONNECTED, &con->flags)) {
 457                 conn_put(con);
 458                 return 0;
 459         }
 460
 461         e = tipc_alloc_entry(data, len);
 462         if (!e) {
 463                 conn_put(con);
 464                 return -ENOMEM;
 465         }
 466
 467         if (addr)
 468                 memcpy(&e->dest, addr, sizeof(struct sockaddr_tipc));
 469
 470         spin_lock_bh(&con->outqueue_lock);
 471         list_add_tail(&e->list, &con->outqueue);
 472         spin_unlock_bh(&con->outqueue_lock);
 473
 474         if (!queue_work(s->send_wq, &con->swork))
 475                 conn_put(con);
 476         return 0;
 477 }
 478
 479 void tipc_conn_terminate(struct tipc_server *s, int conid)
 480 {
 481         struct tipc_conn *con;
 482
 483         con = tipc_conn_lookup(s, conid);
 484         if (con) {
 485                 tipc_close_conn(con);
 486                 conn_put(con);
 487         }
 488 }
 489
 490 static void tipc_send_to_sock(struct tipc_conn *con)
 491 {
 492         int count = 0;
 493         struct tipc_server *s = con->server;
 494         struct outqueue_entry *e;
 495         struct msghdr msg;
 496         int ret;
 497
 498         spin_lock_bh(&con->outqueue_lock);
 499         while (test_bit(CF_CONNECTED, &con->flags)) {
 500                 e = list_entry(con->outqueue.next, struct outqueue_entry,
 501                                list);
 502                 if ((struct list_head *) e == &con->outqueue)
 503                         break;
 504                 spin_unlock_bh(&con->outqueue_lock);
 505
 506                 memset(&msg, 0, sizeof(msg));
 507                 msg.msg_flags = MSG_DONTWAIT;
 508
 509                 if (s->type == SOCK_DGRAM || s->type == SOCK_RDM) {
 510                         msg.msg_name = &e->dest;
 511                         msg.msg_namelen = sizeof(struct sockaddr_tipc);
 512                 }
 513                 ret = kernel_sendmsg(con->sock, &msg, &e->iov, 1,
 514                                      e->iov.iov_len);
 515                 if (ret == -EWOULDBLOCK || ret == 0) {
 516                         cond_resched();
 517                         goto out;
 518                 } else if (ret < 0) {
 519                         goto send_err;
 520                 }
 521
 522                 /* Don't starve users filling buffers */
 523                 if (++count >= MAX_SEND_MSG_COUNT) {
 524                         cond_resched();
 525                         count = 0;
 526                 }
 527
 528                 spin_lock_bh(&con->outqueue_lock);
 529                 list_del(&e->list);
 530                 tipc_free_entry(e);
 531         }
 532         spin_unlock_bh(&con->outqueue_lock);
 533 out:
 534         return;
 535
 536 send_err:
 537         tipc_close_conn(con);
 538 }
 539
 540 static void tipc_recv_work(struct work_struct *work)
 541 {
 542         struct tipc_conn *con = container_of(work, struct tipc_conn, rwork);
 543         int count = 0;
 544
 545         while (test_bit(CF_CONNECTED, &con->flags)) {
 546                 if (con->rx_action(con))
 547                         break;
 548
 549                 /* Don't flood Rx machine */
 550                 if (++count >= MAX_RECV_MSG_COUNT) {
 551                         cond_resched();
 552                         count = 0;
 553                 }
 554         }
 555         conn_put(con);
 556 }
 557
 558 static void tipc_send_work(struct work_struct *work)
 559 {
 560         struct tipc_conn *con = container_of(work, struct tipc_conn, swork);
 561
 562         if (test_bit(CF_CONNECTED, &con->flags))
 563                 tipc_send_to_sock(con);
 564
 565         conn_put(con);
 566 }
 567
 568 static void tipc_work_stop(struct tipc_server *s)
 569 {
 570         destroy_workqueue(s->rcv_wq);
 571         destroy_workqueue(s->send_wq);
 572 }
 573
 574 static int tipc_work_start(struct tipc_server *s)
 575 {
 576         s->rcv_wq = alloc_workqueue("tipc_rcv", WQ_UNBOUND, 1);
 577         if (!s->rcv_wq) {
 578                 pr_err("can't start tipc receive workqueue\n");
 579                 return -ENOMEM;
 580         }
 581
 582         s->send_wq = alloc_workqueue("tipc_send", WQ_UNBOUND, 1);
 583         if (!s->send_wq) {
 584                 pr_err("can't start tipc send workqueue\n");
 585                 destroy_workqueue(s->rcv_wq);
 586                 return -ENOMEM;
 587         }
 588
 589         return 0;
 590 }
 591
 592 int tipc_server_start(struct tipc_server *s)
 593 {
 594         int ret;
 595
 596         spin_lock_init(&s->idr_lock);
 597         idr_init(&s->conn_idr);
 598         s->idr_in_use = 0;
 599
 600         s->rcvbuf_cache = kmem_cache_create(s->name, s->max_rcvbuf_size,
 601                                             0, SLAB_HWCACHE_ALIGN, NULL);
 602         if (!s->rcvbuf_cache)
 603                 return -ENOMEM;
 604
 605         ret = tipc_work_start(s);
 606         if (ret < 0) {
 607                 kmem_cache_destroy(s->rcvbuf_cache);
 608                 return ret;
 609         }
 610         ret = tipc_open_listening_sock(s);
 611         if (ret < 0) {
 612                 tipc_work_stop(s);
 613                 kmem_cache_destroy(s->rcvbuf_cache);
 614                 return ret;
 615         }
 616         return ret;
 617 }
 618
 619 void tipc_server_stop(struct tipc_server *s)
 620 {
 621         struct tipc_conn *con;
 622         int id;
 623
 624         spin_lock_bh(&s->idr_lock);
 625         for (id = 0; s->idr_in_use; id++) {
 626                 con = idr_find(&s->conn_idr, id);
 627                 if (con) {
 628                         spin_unlock_bh(&s->idr_lock);
 629                         tipc_close_conn(con);
 630                         spin_lock_bh(&s->idr_lock);
 631                 }
 632         }
 633         spin_unlock_bh(&s->idr_lock);
 634
 635         tipc_work_stop(s);
 636         kmem_cache_destroy(s->rcvbuf_cache);
 637         idr_destroy(&s->conn_idr);
 638 }