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 "subscr.h"
  40
  41 /**
  42  * struct tipc_subscriber - TIPC network topology subscriber
  43  * @conid: connection identifier to server connecting to subscriber
  44  * @lock: control access to subscriber
  45  * @subscription_list: list of subscription objects for this subscriber
  46  */
  47 struct tipc_subscriber {
  48         int conid;
  49         spinlock_t lock;
  50         struct list_head subscription_list;
  51 };
  52
  53 static void subscr_conn_msg_event(int conid, struct sockaddr_tipc *addr,
  54                                   void *usr_data, void *buf, size_t len);
  55 static void *subscr_named_msg_event(int conid);
  56 static void subscr_conn_shutdown_event(int conid, void *usr_data);
  57
  58 static atomic_t subscription_count = ATOMIC_INIT(0);
  59
  60 static struct sockaddr_tipc topsrv_addr __read_mostly = {
  61         .family                 = AF_TIPC,
  62         .addrtype               = TIPC_ADDR_NAMESEQ,
  63         .addr.nameseq.type      = TIPC_TOP_SRV,
  64         .addr.nameseq.lower     = TIPC_TOP_SRV,
  65         .addr.nameseq.upper     = TIPC_TOP_SRV,
  66         .scope                  = TIPC_NODE_SCOPE
  67 };
  68
  69 static struct tipc_server topsrv __read_mostly = {
  70         .saddr                  = &topsrv_addr,
  71         .imp                    = TIPC_CRITICAL_IMPORTANCE,
  72         .type                   = SOCK_SEQPACKET,
  73         .max_rcvbuf_size        = sizeof(struct tipc_subscr),
  74         .name                   = "topology_server",
  75         .tipc_conn_recvmsg      = subscr_conn_msg_event,
  76         .tipc_conn_new          = subscr_named_msg_event,
  77         .tipc_conn_shutdown     = subscr_conn_shutdown_event,
  78 };
  79
  80 /**
  81  * htohl - convert value to endianness used by destination
  82  * @in: value to convert
  83  * @swap: non-zero if endianness must be reversed
  84  *
  85  * Returns converted value
  86  */
  87 static u32 htohl(u32 in, int swap)
  88 {
  89         return swap ? swab32(in) : in;
  90 }
  91
  92 static void subscr_send_event(struct tipc_subscription *sub, u32 found_lower,
  93                               u32 found_upper, u32 event, u32 port_ref,
  94                               u32 node)
  95 {
  96         struct tipc_subscriber *subscriber = sub->subscriber;
  97         struct kvec msg_sect;
  98
  99         msg_sect.iov_base = (void *)&sub->evt;
 100         msg_sect.iov_len = sizeof(struct tipc_event);
 101         sub->evt.event = htohl(event, sub->swap);
 102         sub->evt.found_lower = htohl(found_lower, sub->swap);
 103         sub->evt.found_upper = htohl(found_upper, sub->swap);
 104         sub->evt.port.ref = htohl(port_ref, sub->swap);
 105         sub->evt.port.node = htohl(node, sub->swap);
 106         tipc_conn_sendmsg(&topsrv, subscriber->conid, NULL, msg_sect.iov_base,
 107                           msg_sect.iov_len);
 108 }
 109
 110 /**
 111  * tipc_subscr_overlap - test for subscription overlap with the given values
 112  *
 113  * Returns 1 if there is overlap, otherwise 0.
 114  */
 115 int tipc_subscr_overlap(struct tipc_subscription *sub, u32 found_lower,
 116                         u32 found_upper)
 117 {
 118         if (found_lower < sub->seq.lower)
 119                 found_lower = sub->seq.lower;
 120         if (found_upper > sub->seq.upper)
 121                 found_upper = sub->seq.upper;
 122         if (found_lower > found_upper)
 123                 return 0;
 124         return 1;
 125 }
 126
 127 /**
 128  * tipc_subscr_report_overlap - issue event if there is subscription overlap
 129  *
 130  * Protected by nameseq.lock in name_table.c
 131  */
 132 void tipc_subscr_report_overlap(struct tipc_subscription *sub, u32 found_lower,
 133                                 u32 found_upper, u32 event, u32 port_ref,
 134                                 u32 node, int must)
 135 {
 136         if (!tipc_subscr_overlap(sub, found_lower, found_upper))
 137                 return;
 138         if (!must && !(sub->filter & TIPC_SUB_PORTS))
 139                 return;
 140
 141         subscr_send_event(sub, found_lower, found_upper, event, port_ref, node);
 142 }
 143
 144 static void subscr_timeout(struct tipc_subscription *sub)
 145 {
 146         struct tipc_subscriber *subscriber = sub->subscriber;
 147
 148         /* The spin lock per subscriber is used to protect its members */
 149         spin_lock_bh(&subscriber->lock);
 150
 151         /* Validate timeout (in case subscription is being cancelled) */
 152         if (sub->timeout == TIPC_WAIT_FOREVER) {
 153                 spin_unlock_bh(&subscriber->lock);
 154                 return;
 155         }
 156
 157         /* Unlink subscription from name table */
 158         tipc_nametbl_unsubscribe(sub);
 159
 160         /* Unlink subscription from subscriber */
 161         list_del(&sub->subscription_list);
 162
 163         spin_unlock_bh(&subscriber->lock);
 164
 165         /* Notify subscriber of timeout */
 166         subscr_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper,
 167                           TIPC_SUBSCR_TIMEOUT, 0, 0);
 168
 169         /* Now destroy subscription */
 170         k_term_timer(&sub->timer);
 171         kfree(sub);
 172         atomic_dec(&subscription_count);
 173 }
 174
 175 /**
 176  * subscr_del - delete a subscription within a subscription list
 177  *
 178  * Called with subscriber lock held.
 179  */
 180 static void subscr_del(struct tipc_subscription *sub)
 181 {
 182         tipc_nametbl_unsubscribe(sub);
 183         list_del(&sub->subscription_list);
 184         kfree(sub);
 185         atomic_dec(&subscription_count);
 186 }
 187
 188 /**
 189  * subscr_terminate - terminate communication with a subscriber
 190  *
 191  * Note: Must call it in process context since it might sleep.
 192  */
 193 static void subscr_terminate(struct tipc_subscriber *subscriber)
 194 {
 195         tipc_conn_terminate(&topsrv, subscriber->conid);
 196 }
 197
 198 static void subscr_release(struct tipc_subscriber *subscriber)
 199 {
 200         struct tipc_subscription *sub;
 201         struct tipc_subscription *sub_temp;
 202
 203         spin_lock_bh(&subscriber->lock);
 204
 205         /* Destroy any existing subscriptions for subscriber */
 206         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 207                                  subscription_list) {
 208                 if (sub->timeout != TIPC_WAIT_FOREVER) {
 209                         spin_unlock_bh(&subscriber->lock);
 210                         k_cancel_timer(&sub->timer);
 211                         k_term_timer(&sub->timer);
 212                         spin_lock_bh(&subscriber->lock);
 213                 }
 214                 subscr_del(sub);
 215         }
 216         spin_unlock_bh(&subscriber->lock);
 217
 218         /* Now destroy subscriber */
 219         kfree(subscriber);
 220 }
 221
 222 /**
 223  * subscr_cancel - handle subscription cancellation request
 224  *
 225  * Called with subscriber lock held. Routine must temporarily release lock
 226  * to enable the subscription timeout routine to finish without deadlocking;
 227  * the lock is then reclaimed to allow caller to release it upon return.
 228  *
 229  * Note that fields of 's' use subscriber's endianness!
 230  */
 231 static void subscr_cancel(struct tipc_subscr *s,
 232                           struct tipc_subscriber *subscriber)
 233 {
 234         struct tipc_subscription *sub;
 235         struct tipc_subscription *sub_temp;
 236         int found = 0;
 237
 238         /* Find first matching subscription, exit if not found */
 239         list_for_each_entry_safe(sub, sub_temp, &subscriber->subscription_list,
 240                                  subscription_list) {
 241                 if (!memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) {
 242                         found = 1;
 243                         break;
 244                 }
 245         }
 246         if (!found)
 247                 return;
 248
 249         /* Cancel subscription timer (if used), then delete subscription */
 250         if (sub->timeout != TIPC_WAIT_FOREVER) {
 251                 sub->timeout = TIPC_WAIT_FOREVER;
 252                 spin_unlock_bh(&subscriber->lock);
 253                 k_cancel_timer(&sub->timer);
 254                 k_term_timer(&sub->timer);
 255                 spin_lock_bh(&subscriber->lock);
 256         }
 257         subscr_del(sub);
 258 }
 259
 260 /**
 261  * subscr_subscribe - create subscription for subscriber
 262  *
 263  * Called with subscriber lock held.
 264  */
 265 static int subscr_subscribe(struct tipc_subscr *s,
 266                             struct tipc_subscriber *subscriber,
 267                             struct tipc_subscription **sub_p) {
 268         struct tipc_subscription *sub;
 269         int swap;
 270
 271         /* Determine subscriber's endianness */
 272         swap = !(s->filter & (TIPC_SUB_PORTS | TIPC_SUB_SERVICE));
 273
 274         /* Detect & process a subscription cancellation request */
 275         if (s->filter & htohl(TIPC_SUB_CANCEL, swap)) {
 276                 s->filter &= ~htohl(TIPC_SUB_CANCEL, swap);
 277                 subscr_cancel(s, subscriber);
 278                 return 0;
 279         }
 280
 281         /* Refuse subscription if global limit exceeded */
 282         if (atomic_read(&subscription_count) >= TIPC_MAX_SUBSCRIPTIONS) {
 283                 pr_warn("Subscription rejected, limit reached (%u)\n",
 284                         TIPC_MAX_SUBSCRIPTIONS);
 285                 return -EINVAL;
 286         }
 287
 288         /* Allocate subscription object */
 289         sub = kmalloc(sizeof(*sub), GFP_ATOMIC);
 290         if (!sub) {
 291                 pr_warn("Subscription rejected, no memory\n");
 292                 return -ENOMEM;
 293         }
 294
 295         /* Initialize subscription object */
 296         sub->seq.type = htohl(s->seq.type, swap);
 297         sub->seq.lower = htohl(s->seq.lower, swap);
 298         sub->seq.upper = htohl(s->seq.upper, swap);
 299         sub->timeout = htohl(s->timeout, swap);
 300         sub->filter = htohl(s->filter, swap);
 301         if ((!(sub->filter & TIPC_SUB_PORTS) ==
 302              !(sub->filter & TIPC_SUB_SERVICE)) ||
 303             (sub->seq.lower > sub->seq.upper)) {
 304                 pr_warn("Subscription rejected, illegal request\n");
 305                 kfree(sub);
 306                 return -EINVAL;
 307         }
 308         list_add(&sub->subscription_list, &subscriber->subscription_list);
 309         sub->subscriber = subscriber;
 310         sub->swap = swap;
 311         memcpy(&sub->evt.s, s, sizeof(struct tipc_subscr));
 312         atomic_inc(&subscription_count);
 313         if (sub->timeout != TIPC_WAIT_FOREVER) {
 314                 k_init_timer(&sub->timer,
 315                              (Handler)subscr_timeout, (unsigned long)sub);
 316                 k_start_timer(&sub->timer, sub->timeout);
 317         }
 318         *sub_p = sub;
 319         return 0;
 320 }
 321
 322 /* Handle one termination request for the subscriber */
 323 static void subscr_conn_shutdown_event(int conid, void *usr_data)
 324 {
 325         subscr_release((struct tipc_subscriber *)usr_data);
 326 }
 327
 328 /* Handle one request to create a new subscription for the subscriber */
 329 static void subscr_conn_msg_event(int conid, struct sockaddr_tipc *addr,
 330                                   void *usr_data, void *buf, size_t len)
 331 {
 332         struct tipc_subscriber *subscriber = usr_data;
 333         struct tipc_subscription *sub = NULL;
 334
 335         spin_lock_bh(&subscriber->lock);
 336         if (subscr_subscribe((struct tipc_subscr *)buf, subscriber, &sub) < 0) {
 337                 spin_unlock_bh(&subscriber->lock);
 338                 subscr_terminate(subscriber);
 339                 return;
 340         }
 341         if (sub)
 342                 tipc_nametbl_subscribe(sub);
 343         spin_unlock_bh(&subscriber->lock);
 344 }
 345
 346
 347 /* Handle one request to establish a new subscriber */
 348 static void *subscr_named_msg_event(int conid)
 349 {
 350         struct tipc_subscriber *subscriber;
 351
 352         /* Create subscriber object */
 353         subscriber = kzalloc(sizeof(struct tipc_subscriber), GFP_ATOMIC);
 354         if (subscriber == NULL) {
 355                 pr_warn("Subscriber rejected, no memory\n");
 356                 return NULL;
 357         }
 358         INIT_LIST_HEAD(&subscriber->subscription_list);
 359         subscriber->conid = conid;
 360         spin_lock_init(&subscriber->lock);
 361
 362         return (void *)subscriber;
 363 }
 364
 365 int tipc_subscr_start(void)
 366 {
 367         return tipc_server_start(&topsrv);
 368 }
 369
 370 void tipc_subscr_stop(void)
 371 {
 372         tipc_server_stop(&topsrv);
 373 }