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
 100         msg_sect.iov_base = (void *)&sub->evt;
 101         msg_sect.iov_len = sizeof(struct tipc_event);
 102         sub->evt.event = htohl(event, sub->swap);
 103         sub->evt.found_lower = htohl(found_lower, sub->swap);
 104         sub->evt.found_upper = htohl(found_upper, sub->swap);
 105         sub->evt.port.ref = htohl(port_ref, sub->swap);
 106         sub->evt.port.node = htohl(node, sub->swap);
 107         tipc_conn_sendmsg(&topsrv, subscriber->conid, NULL, msg_sect.iov_base,
 108                           msg_sect.iov_len);
 109 }
 110
 111 /**
 112  * tipc_subscr_overlap - test for subscription overlap with the given values
 113  *
 114  * Returns 1 if there is overlap, otherwise 0.
 115  */
 116 int tipc_subscr_overlap(struct tipc_subscription *sub, u32 found_lower,
 117                         u32 found_upper)
 118 {
 119         if (found_lower < sub->seq.lower)
 120                 found_lower = sub->seq.lower;
 121         if (found_upper > sub->seq.upper)
 122                 found_upper = sub->seq.upper;
 123         if (found_lower > found_upper)
 124                 return 0;
 125         return 1;
 126 }
 127
 128 /**
 129  * tipc_subscr_report_overlap - issue event if there is subscription overlap
 130  *
 131  * Protected by nameseq.lock in name_table.c
 132  */
 133 void tipc_subscr_report_overlap(struct tipc_subscription *sub, u32 found_lower,
 134                                 u32 found_upper, u32 event, u32 port_ref,
 135                                 u32 node, int must)
 136 {
 137         if (!tipc_subscr_overlap(sub, found_lower, found_upper))
 138                 return;
 139         if (!must && !(sub->filter & TIPC_SUB_PORTS))
 140                 return;
 141
 142         subscr_send_event(sub, found_lower, found_upper, event, port_ref, node);
 143 }
 144
 145 static void subscr_timeout(struct tipc_subscription *sub)
 146 {
 147         struct tipc_subscriber *subscriber = sub->subscriber;
 148
 149         /* The spin lock per subscriber is used to protect its members */
 150         spin_lock_bh(&subscriber->lock);
 151
 152         /* Validate if the connection related to the subscriber is
 153          * closed (in case subscriber is terminating)
 154          */
 155         if (subscriber->conid == 0) {
 156                 spin_unlock_bh(&subscriber->lock);
 157                 return;
 158         }
 159
 160         /* Validate timeout (in case subscription is being cancelled) */
 161         if (sub->timeout == TIPC_WAIT_FOREVER) {
 162                 spin_unlock_bh(&subscriber->lock);
 163                 return;
 164         }
 165
 166         /* Unlink subscription from name table */
 167         tipc_nametbl_unsubscribe(sub);
 168
 169         /* Unlink subscription from subscriber */
 170         list_del(&sub->subscription_list);
 171
 172         spin_unlock_bh(&subscriber->lock);
 173
 174         /* Notify subscriber of timeout */
 175         subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
 176                           TIPC_SUBSCR_TIMEOUT, 0, 0);
 177
 178         /* Now destroy subscription */
 179         k_term_timer(&sub->timer);
 180         kfree(sub);
 181         atomic_dec(&subscription_count);
 182 }
 183
 184 /**
 185  * subscr_del - delete a subscription within a subscription list
 186  *
 187  * Called with subscriber lock held.
 188  */
 189 static void subscr_del(struct tipc_subscription *sub)
 190 {
 191         tipc_nametbl_unsubscribe(sub);
 192         list_del(&sub->subscription_list);
 193         kfree(sub);
 194         atomic_dec(&subscription_count);
 195 }
 196
 197 /**
 198  * subscr_terminate - terminate communication with a subscriber
 199  *
 200  * Note: Must call it in process context since it might sleep.
 201  */
 202 static void subscr_terminate(struct tipc_subscriber *subscriber)
 203 {
 204         tipc_conn_terminate(&topsrv, subscriber->conid);
 205 }
 206
 207 static void subscr_release(struct tipc_subscriber *subscriber)
 208 {
 209         struct tipc_subscription *sub;
 210         struct tipc_subscription *sub_temp;
 211
 212         spin_lock_bh(&subscriber->lock);
 213
 214         /* Invalidate subscriber reference */
 215         subscriber->conid = 0;
 216
 217         /* Destroy any existing subscriptions for subscriber */
 218         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 219                                  subscription_list) {
 220                 if (sub->timeout != TIPC_WAIT_FOREVER) {
 221                         spin_unlock_bh(&subscriber->lock);
 222                         k_cancel_timer(&sub->timer);
 223                         k_term_timer(&sub->timer);
 224                         spin_lock_bh(&subscriber->lock);
 225                 }
 226                 subscr_del(sub);
 227         }
 228         spin_unlock_bh(&subscriber->lock);
 229
 230         /* Now destroy subscriber */
 231         kfree(subscriber);
 232 }
 233
 234 /**
 235  * subscr_cancel - handle subscription cancellation request
 236  *
 237  * Called with subscriber lock held. Routine must temporarily release lock
 238  * to enable the subscription timeout routine to finish without deadlocking;
 239  * the lock is then reclaimed to allow caller to release it upon return.
 240  *
 241  * Note that fields of 's' use subscriber's endianness!
 242  */
 243 static void subscr_cancel(struct tipc_subscr *s,
 244                           struct tipc_subscriber *subscriber)
 245 {
 246         struct tipc_subscription *sub;
 247         struct tipc_subscription *sub_temp;
 248         int found = 0;
 249
 250         /* Find first matching subscription, exit if not found */
 251         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 252                                  subscription_list) {
 253                 if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
 254                         found = 1;
 255                         break;
 256                 }
 257         }
 258         if (!found)
 259                 return;
 260
 261         /* Cancel subscription timer (if used), then delete subscription */
 262         if (sub->timeout != TIPC_WAIT_FOREVER) {
 263                 sub->timeout = TIPC_WAIT_FOREVER;
 264                 spin_unlock_bh(&subscriber->lock);
 265                 k_cancel_timer(&sub->timer);
 266                 k_term_timer(&sub->timer);
 267                 spin_lock_bh(&subscriber->lock);
 268         }
 269         subscr_del(sub);
 270 }
 271
 272 /**
 273  * subscr_subscribe - create subscription for subscriber
 274  *
 275  * Called with subscriber lock held.
 276  */
 277 static struct tipc_subscription *subscr_subscribe(struct tipc_subscr *s,
 278                                              struct tipc_subscriber *subscriber)
 279 {
 280         struct tipc_subscription *sub;
 281         int swap;
 282
 283         /* Determine subscriber's endianness */
 284         swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE));
 285
 286         /* Detect & process a subscription cancellation request */
 287         if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
 288                 s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
 289                 subscr_cancel(s, subscriber);
 290                 return NULL;
 291         }
 292
 293         /* Refuse subscription if global limit exceeded */
 294         if (atomic_read(&subscription_count) >= TIPC_MAX_SUBSCRIPTIONS) {
 295                 pr_warn("Subscription rejected, limit reached (%u)\n",
 296                         TIPC_MAX_SUBSCRIPTIONS);
 297                 subscr_terminate(subscriber);
 298                 return NULL;
 299         }
 300
 301         /* Allocate subscription object */
 302         sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
 303         if (!sub) {
 304                 pr_warn("Subscription rejected, no memory\n");
 305                 subscr_terminate(subscriber);
 306                 return NULL;
 307         }
 308
 309         /* Initialize subscription object */
 310         sub->seq.type = htohl(s->seq.type, swap);
 311         sub->seq.lower = htohl(s->seq.lower, swap);
 312         sub->seq.upper = htohl(s->seq.upper, swap);
 313         sub->timeout = htohl(s->timeout, swap);
 314         sub->filter = htohl(s->filter, swap);
 315         if ((!(sub->filter & TIPC_SUB_PORTS) ==
 316              !(sub->filter & TIPC_SUB_SERVICE)) ||
 317             (sub->seq.lower > sub->seq.upper)) {
 318                 pr_warn("Subscription rejected, illegal request\n");
 319                 kfree(sub);
 320                 subscr_terminate(subscriber);
 321                 return NULL;
 322         }
 323         INIT_LIST_HEAD(&sub->nameseq_list);
 324         list_add(&sub->subscription_list, &subscriber->subscription_list);
 325         sub->subscriber = subscriber;
 326         sub->swap = swap;
 327         memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
 328         atomic_inc(&subscription_count);
 329         if (sub->timeout != TIPC_WAIT_FOREVER) {
 330                 k_init_timer(&sub->timer,
 331                              (Handler)subscr_timeout, (unsigned long)sub);
 332                 k_start_timer(&sub->timer, sub->timeout);
 333         }
 334
 335         return sub;
 336 }
 337
 338 /* Handle one termination request for the subscriber */
 339 static void subscr_conn_shutdown_event(int conid, void *usr_data)
 340 {
 341         subscr_release((struct tipc_subscriber *)usr_data);
 342 }
 343
 344 /* Handle one request to create a new subscription for the subscriber */
 345 static void subscr_conn_msg_event(int conid, struct sockaddr_tipc *addr,
 346                                   void *usr_data, void *buf, size_t len)
 347 {
 348         struct tipc_subscriber *subscriber = usr_data;
 349         struct tipc_subscription *sub;
 350
 351         spin_lock_bh(&subscriber->lock);
 352         sub = subscr_subscribe((struct tipc_subscr *)buf, subscriber);
 353         if (sub)
 354                 tipc_nametbl_subscribe(sub);
 355         spin_unlock_bh(&subscriber->lock);
 356 }
 357
 358
 359 /* Handle one request to establish a new subscriber */
 360 static void *subscr_named_msg_event(int conid)
 361 {
 362         struct tipc_subscriber *subscriber;
 363
 364         /* Create subscriber object */
 365         subscriber = kzalloc(sizeof(struct tipc_subscriber), GFP_ATOMIC);
 366         if (subscriber == NULL) {
 367                 pr_warn("Subscriber rejected, no memory\n");
 368                 return NULL;
 369         }
 370         INIT_LIST_HEAD(&subscriber->subscription_list);
 371         subscriber->conid = conid;
 372         spin_lock_init(&subscriber->lock);
 373
 374         return (void *)subscriber;
 375 }
 376
 377 int tipc_subscr_start(void)
 378 {
 379         return tipc_server_start(&topsrv);
 380 }
 381
 382 void tipc_subscr_stop(void)
 383 {
 384         tipc_server_stop(&topsrv);
 385 }