net/tipc/subscr.c

   1 /*
   2  * net/tipc/subscr.c: TIPC network topology service
   3  *
   4  * Copyright (c) 2000-2006, Ericsson AB
   5  * Copyright (c) 2005-2007, 2010-2013, Wind River Systems
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted provided that the following conditions are met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright
  12  *    notice, this list of conditions and the following disclaimer.
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  * 3. Neither the names of the copyright holders nor the names of its
  17  *    contributors may be used to endorse or promote products derived from
  18  *    this software without specific prior written permission.
  19  *
  20  * Alternatively, this software may be distributed under the terms of the
  21  * GNU General Public License ("GPL") version 2 as published by the Free
  22  * Software Foundation.
  23  *
  24  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  25  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  26  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  27  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  28  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  29  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  30  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  31  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  32  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  33  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  34  * POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "core.h"
  38 #include "name_table.h"
  39 #include "port.h"
  40 #include "subscr.h"
  41
  42 /**
  43  * struct tipc_subscriber - TIPC network topology subscriber
  44  * @conid: connection identifier to server connecting to subscriber
  45  * @lock: control access to subscriber
  46  * @subscription_list: list of subscription objects for this subscriber
  47  */
  48 struct tipc_subscriber {
  49         int conid;
  50         spinlock_t lock;
  51         struct list_head subscription_list;
  52 };
  53
  54 static void subscr_conn_msg_event(int conid, struct sockaddr_tipc *addr,
  55                                   void *usr_data, void *buf, size_t len);
  56 static void *subscr_named_msg_event(int conid);
  57 static void subscr_conn_shutdown_event(int conid, void *usr_data);
  58
  59 static atomic_t subscription_count = ATOMIC_INIT(0);
  60
  61 static struct sockaddr_tipc topsrv_addr __read_mostly = {
  62         .family                 = AF_TIPC,
  63         .addrtype               = TIPC_ADDR_NAMESEQ,
  64         .addr.nameseq.type      = TIPC_TOP_SRV,
  65         .addr.nameseq.lower     = TIPC_TOP_SRV,
  66         .addr.nameseq.upper     = TIPC_TOP_SRV,
  67         .scope                  = TIPC_NODE_SCOPE
  68 };
  69
  70 static struct tipc_server topsrv __read_mostly = {
  71         .saddr                  = &topsrv_addr,
  72         .imp                    = TIPC_CRITICAL_IMPORTANCE,
  73         .type                   = SOCK_SEQPACKET,
  74         .max_rcvbuf_size        = sizeof(struct tipc_subscr),
  75         .name                   = "topology_server",
  76         .tipc_conn_recvmsg      = subscr_conn_msg_event,
  77         .tipc_conn_new          = subscr_named_msg_event,
  78         .tipc_conn_shutdown     = subscr_conn_shutdown_event,
  79 };
  80
  81 /**
  82  * htohl - convert value to endianness used by destination
  83  * @in: value to convert
  84  * @swap: non-zero if endianness must be reversed
  85  *
  86  * Returns converted value
  87  */
  88 static u32 htohl(u32 in, int swap)
  89 {
  90         return swap ? swab32(in) : in;
  91 }
  92
  93 static void subscr_send_event(struct tipc_subscription *sub, u32 found_lower,
  94                               u32 found_upper, u32 event, u32 port_ref,
  95                               u32 node)
  96 {
  97         struct tipc_subscriber *subscriber = sub->subscriber;
  98         struct kvec msg_sect;
  99         int ret;
 100
 101         msg_sect.iov_base = (void *)&sub->evt;
 102         msg_sect.iov_len = sizeof(struct tipc_event);
 103
 104         sub->evt.event = htohl(event, sub->swap);
 105         sub->evt.found_lower = htohl(found_lower, sub->swap);
 106         sub->evt.found_upper = htohl(found_upper, sub->swap);
 107         sub->evt.port.ref = htohl(port_ref, sub->swap);
 108         sub->evt.port.node = htohl(node, sub->swap);
 109         ret = tipc_conn_sendmsg(&topsrv, subscriber->conid, NULL,
 110                                 msg_sect.iov_base, msg_sect.iov_len);
 111         if (ret < 0)
 112                 pr_err("Sending subscription event failed, no memory\n");
 113 }
 114
 115 /**
 116  * tipc_subscr_overlap - test for subscription overlap with the given values
 117  *
 118  * Returns 1 if there is overlap, otherwise 0.
 119  */
 120 int tipc_subscr_overlap(struct tipc_subscription *sub, u32 found_lower,
 121                         u32 found_upper)
 122 {
 123         if (found_lower < sub->seq.lower)
 124                 found_lower = sub->seq.lower;
 125         if (found_upper > sub->seq.upper)
 126                 found_upper = sub->seq.upper;
 127         if (found_lower > found_upper)
 128                 return 0;
 129         return 1;
 130 }
 131
 132 /**
 133  * tipc_subscr_report_overlap - issue event if there is subscription overlap
 134  *
 135  * Protected by nameseq.lock in name_table.c
 136  */
 137 void tipc_subscr_report_overlap(struct tipc_subscription *sub, u32 found_lower,
 138                                 u32 found_upper, u32 event, u32 port_ref,
 139                                 u32 node, int must)
 140 {
 141         if (!tipc_subscr_overlap(sub, found_lower, found_upper))
 142                 return;
 143         if (!must && !(sub->filter & TIPC_SUB_PORTS))
 144                 return;
 145
 146         subscr_send_event(sub, found_lower, found_upper, event, port_ref, node);
 147 }
 148
 149 static void subscr_timeout(struct tipc_subscription *sub)
 150 {
 151         struct tipc_subscriber *subscriber = sub->subscriber;
 152
 153         /* The spin lock per subscriber is used to protect its members */
 154         spin_lock_bh(&subscriber->lock);
 155
 156         /* Validate if the connection related to the subscriber is
 157          * closed (in case subscriber is terminating)
 158          */
 159         if (subscriber->conid == 0) {
 160                 spin_unlock_bh(&subscriber->lock);
 161                 return;
 162         }
 163
 164         /* Validate timeout (in case subscription is being cancelled) */
 165         if (sub->timeout == TIPC_WAIT_FOREVER) {
 166                 spin_unlock_bh(&subscriber->lock);
 167                 return;
 168         }
 169
 170         /* Unlink subscription from name table */
 171         tipc_nametbl_unsubscribe(sub);
 172
 173         /* Unlink subscription from subscriber */
 174         list_del(&sub->subscription_list);
 175
 176         spin_unlock_bh(&subscriber->lock);
 177
 178         /* Notify subscriber of timeout */
 179         subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
 180                           TIPC_SUBSCR_TIMEOUT, 0, 0);
 181
 182         /* Now destroy subscription */
 183         k_term_timer(&sub->timer);
 184         kfree(sub);
 185         atomic_dec(&subscription_count);
 186 }
 187
 188 /**
 189  * subscr_del - delete a subscription within a subscription list
 190  *
 191  * Called with subscriber lock held.
 192  */
 193 static void subscr_del(struct tipc_subscription *sub)
 194 {
 195         tipc_nametbl_unsubscribe(sub);
 196         list_del(&sub->subscription_list);
 197         kfree(sub);
 198         atomic_dec(&subscription_count);
 199 }
 200
 201 /**
 202  * subscr_terminate - terminate communication with a subscriber
 203  *
 204  * Note: Must call it in process context since it might sleep.
 205  */
 206 static void subscr_terminate(struct tipc_subscriber *subscriber)
 207 {
 208         tipc_conn_terminate(&topsrv, subscriber->conid);
 209 }
 210
 211 static void subscr_release(struct tipc_subscriber *subscriber)
 212 {
 213         struct tipc_subscription *sub;
 214         struct tipc_subscription *sub_temp;
 215
 216         spin_lock_bh(&subscriber->lock);
 217
 218         /* Invalidate subscriber reference */
 219         subscriber->conid = 0;
 220
 221         /* Destroy any existing subscriptions for subscriber */
 222         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 223                                  subscription_list) {
 224                 if (sub->timeout != TIPC_WAIT_FOREVER) {
 225                         spin_unlock_bh(&subscriber->lock);
 226                         k_cancel_timer(&sub->timer);
 227                         k_term_timer(&sub->timer);
 228                         spin_lock_bh(&subscriber->lock);
 229                 }
 230                 subscr_del(sub);
 231         }
 232         spin_unlock_bh(&subscriber->lock);
 233
 234         /* Now destroy subscriber */
 235         kfree(subscriber);
 236 }
 237
 238 /**
 239  * subscr_cancel - handle subscription cancellation request
 240  *
 241  * Called with subscriber lock held. Routine must temporarily release lock
 242  * to enable the subscription timeout routine to finish without deadlocking;
 243  * the lock is then reclaimed to allow caller to release it upon return.
 244  *
 245  * Note that fields of 's' use subscriber's endianness!
 246  */
 247 static void subscr_cancel(struct tipc_subscr *s,
 248                           struct tipc_subscriber *subscriber)
 249 {
 250         struct tipc_subscription *sub;
 251         struct tipc_subscription *sub_temp;
 252         int found = 0;
 253
 254         /* Find first matching subscription, exit if not found */
 255         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 256                                  subscription_list) {
 257                 if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
 258                         found = 1;
 259                         break;
 260                 }
 261         }
 262         if (!found)
 263                 return;
 264
 265         /* Cancel subscription timer (if used), then delete subscription */
 266         if (sub->timeout != TIPC_WAIT_FOREVER) {
 267                 sub->timeout = TIPC_WAIT_FOREVER;
 268                 spin_unlock_bh(&subscriber->lock);
 269                 k_cancel_timer(&sub->timer);
 270                 k_term_timer(&sub->timer);
 271                 spin_lock_bh(&subscriber->lock);
 272         }
 273         subscr_del(sub);
 274 }
 275
 276 /**
 277  * subscr_subscribe - create subscription for subscriber
 278  *
 279  * Called with subscriber lock held.
 280  */
 281 static struct tipc_subscription *subscr_subscribe(struct tipc_subscr *s,
 282                                              struct tipc_subscriber *subscriber)
 283 {
 284         struct tipc_subscription *sub;
 285         int swap;
 286
 287         /* Determine subscriber's endianness */
 288         swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE));
 289
 290         /* Detect & process a subscription cancellation request */
 291         if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
 292                 s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
 293                 subscr_cancel(s, subscriber);
 294                 return NULL;
 295         }
 296
 297         /* Refuse subscription if global limit exceeded */
 298         if (atomic_read(&subscription_count) >= TIPC_MAX_SUBSCRIPTIONS) {
 299                 pr_warn("Subscription rejected, limit reached (%u)\n",
 300                         TIPC_MAX_SUBSCRIPTIONS);
 301                 subscr_terminate(subscriber);
 302                 return NULL;
 303         }
 304
 305         /* Allocate subscription object */
 306         sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
 307         if (!sub) {
 308                 pr_warn("Subscription rejected, no memory\n");
 309                 subscr_terminate(subscriber);
 310                 return NULL;
 311         }
 312
 313         /* Initialize subscription object */
 314         sub->seq.type = htohl(s->seq.type, swap);
 315         sub->seq.lower = htohl(s->seq.lower, swap);
 316         sub->seq.upper = htohl(s->seq.upper, swap);
 317         sub->timeout = htohl(s->timeout, swap);
 318         sub->filter = htohl(s->filter, swap);
 319         if ((!(sub->filter & TIPC_SUB_PORTS) ==
 320              !(sub->filter & TIPC_SUB_SERVICE)) ||
 321             (sub->seq.lower > sub->seq.upper)) {
 322                 pr_warn("Subscription rejected, illegal request\n");
 323                 kfree(sub);
 324                 subscr_terminate(subscriber);
 325                 return NULL;
 326         }
 327         INIT_LIST_HEAD(&sub->nameseq_list);
 328         list_add(&sub->subscription_list, &subscriber->subscription_list);
 329         sub->subscriber = subscriber;
 330         sub->swap = swap;
 331         memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
 332         atomic_inc(&subscription_count);
 333         if (sub->timeout != TIPC_WAIT_FOREVER) {
 334                 k_init_timer(&sub->timer,
 335                              (Handler)subscr_timeout, (unsigned long)sub);
 336                 k_start_timer(&sub->timer, sub->timeout);
 337         }
 338
 339         return sub;
 340 }
 341
 342 /* Handle one termination request for the subscriber */
 343 static void subscr_conn_shutdown_event(int conid, void *usr_data)
 344 {
 345         subscr_release((struct tipc_subscriber *)usr_data);
 346 }
 347
 348 /* Handle one request to create a new subscription for the subscriber */
 349 static void subscr_conn_msg_event(int conid, struct sockaddr_tipc *addr,
 350                                   void *usr_data, void *buf, size_t len)
 351 {
 352         struct tipc_subscriber *subscriber = usr_data;
 353         struct tipc_subscription *sub;
 354
 355         spin_lock_bh(&subscriber->lock);
 356         sub = subscr_subscribe((struct tipc_subscr *)buf, subscriber);
 357         if (sub)
 358                 tipc_nametbl_subscribe(sub);
 359         spin_unlock_bh(&subscriber->lock);
 360 }
 361
 362
 363 /* Handle one request to establish a new subscriber */
 364 static void *subscr_named_msg_event(int conid)
 365 {
 366         struct tipc_subscriber *subscriber;
 367
 368         /* Create subscriber object */
 369         subscriber = kzalloc(sizeof(struct tipc_subscriber), GFP_ATOMIC);
 370         if (subscriber == NULL) {
 371                 pr_warn("Subscriber rejected, no memory\n");
 372                 return NULL;
 373         }
 374         INIT_LIST_HEAD(&subscriber->subscription_list);
 375         subscriber->conid = conid;
 376         spin_lock_init(&subscriber->lock);
 377
 378         return (void *)subscriber;
 379 }
 380
 381 int tipc_subscr_start(void)
 382 {
 383         return tipc_server_start(&topsrv);
 384 }
 385
 386 void tipc_subscr_stop(void)
 387 {
 388         tipc_server_stop(&topsrv);
 389 }