net/tipc/discover.c

   1 /*
   2  * net/tipc/discover.c
   3  *
   4  * Copyright (c) 2003-2006, 2014, Ericsson AB
   5  * Copyright (c) 2005-2006, 2010-2011, 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 "link.h"
  39 #include "discover.h"
  40
  41 /* min delay during bearer start up */
  42 #define TIPC_LINK_REQ_INIT      msecs_to_jiffies(125)
  43 /* max delay if bearer has no links */
  44 #define TIPC_LINK_REQ_FAST      msecs_to_jiffies(1000)
  45 /* max delay if bearer has links */
  46 #define TIPC_LINK_REQ_SLOW      msecs_to_jiffies(60000)
  47 /* indicates no timer in use */
  48 #define TIPC_LINK_REQ_INACTIVE  0xffffffff
  49
  50
  51 /**
  52  * struct tipc_link_req - information about an ongoing link setup request
  53  * @bearer_id: identity of bearer issuing requests
  54  * @net: network namespace instance
  55  * @dest: destination address for request messages
  56  * @domain: network domain to which links can be established
  57  * @num_nodes: number of nodes currently discovered (i.e. with an active link)
  58  * @lock: spinlock for controlling access to requests
  59  * @buf: request message to be (repeatedly) sent
  60  * @timer: timer governing period between requests
  61  * @timer_intv: current interval between requests (in ms)
  62  */
  63 struct tipc_link_req {
  64         u32 bearer_id;
  65         struct tipc_media_addr dest;
  66         struct net *net;
  67         u32 domain;
  68         int num_nodes;
  69         spinlock_t lock;
  70         struct sk_buff *buf;
  71         struct timer_list timer;
  72         unsigned long timer_intv;
  73 };
  74
  75 /**
  76  * tipc_disc_init_msg - initialize a link setup message
  77  * @net: the applicable net namespace
  78  * @type: message type (request or response)
  79  * @b_ptr: ptr to bearer issuing message
  80  */
  81 static void tipc_disc_init_msg(struct net *net, struct sk_buff *buf, u32 type,
  82                                struct tipc_bearer *b_ptr)
  83 {
  84         struct tipc_net *tn = net_generic(net, tipc_net_id);
  85         struct tipc_msg *msg;
  86         u32 dest_domain = b_ptr->domain;
  87
  88         msg = buf_msg(buf);
  89         tipc_msg_init(msg, LINK_CONFIG, type, INT_H_SIZE, dest_domain);
  90         msg_set_non_seq(msg, 1);
  91         msg_set_node_sig(msg, tipc_random);
  92         msg_set_dest_domain(msg, dest_domain);
  93         msg_set_bc_netid(msg, tn->net_id);
  94         b_ptr->media->addr2msg(msg_media_addr(msg), &b_ptr->addr);
  95 }
  96
  97 /**
  98  * disc_dupl_alert - issue node address duplication alert
  99  * @b_ptr: pointer to bearer detecting duplication
 100  * @node_addr: duplicated node address
 101  * @media_addr: media address advertised by duplicated node
 102  */
 103 static void disc_dupl_alert(struct tipc_bearer *b_ptr, u32 node_addr,
 104                             struct tipc_media_addr *media_addr)
 105 {
 106         char node_addr_str[16];
 107         char media_addr_str[64];
 108
 109         tipc_addr_string_fill(node_addr_str, node_addr);
 110         tipc_media_addr_printf(media_addr_str, sizeof(media_addr_str),
 111                                media_addr);
 112         pr_warn("Duplicate %s using %s seen on <%s>\n", node_addr_str,
 113                 media_addr_str, b_ptr->name);
 114 }
 115
 116 /**
 117  * tipc_disc_rcv - handle incoming discovery message (request or response)
 118  * @net: the applicable net namespace
 119  * @buf: buffer containing message
 120  * @bearer: bearer that message arrived on
 121  */
 122 void tipc_disc_rcv(struct net *net, struct sk_buff *buf,
 123                    struct tipc_bearer *bearer)
 124 {
 125         struct tipc_net *tn = net_generic(net, tipc_net_id);
 126         struct tipc_node *node;
 127         struct tipc_link *link;
 128         struct tipc_media_addr maddr;
 129         struct sk_buff *rbuf;
 130         struct tipc_msg *msg = buf_msg(buf);
 131         u32 ddom = msg_dest_domain(msg);
 132         u32 onode = msg_prevnode(msg);
 133         u32 net_id = msg_bc_netid(msg);
 134         u32 mtyp = msg_type(msg);
 135         u32 signature = msg_node_sig(msg);
 136         bool addr_match = false;
 137         bool sign_match = false;
 138         bool link_up = false;
 139         bool accept_addr = false;
 140         bool accept_sign = false;
 141         bool respond = false;
 142
 143         bearer->media->msg2addr(bearer, &maddr, msg_media_addr(msg));
 144         kfree_skb(buf);
 145
 146         /* Ensure message from node is valid and communication is permitted */
 147         if (net_id != tn->net_id)
 148                 return;
 149         if (maddr.broadcast)
 150                 return;
 151         if (!tipc_addr_domain_valid(ddom))
 152                 return;
 153         if (!tipc_addr_node_valid(onode))
 154                 return;
 155
 156         if (in_own_node(onode)) {
 157                 if (memcmp(&maddr, &bearer->addr, sizeof(maddr)))
 158                         disc_dupl_alert(bearer, tipc_own_addr, &maddr);
 159                 return;
 160         }
 161         if (!tipc_in_scope(ddom, tipc_own_addr))
 162                 return;
 163         if (!tipc_in_scope(bearer->domain, onode))
 164                 return;
 165
 166         /* Locate, or if necessary, create, node: */
 167         node = tipc_node_find(net, onode);
 168         if (!node)
 169                 node = tipc_node_create(net, onode);
 170         if (!node)
 171                 return;
 172
 173         tipc_node_lock(node);
 174         link = node->links[bearer->identity];
 175
 176         /* Prepare to validate requesting node's signature and media address */
 177         sign_match = (signature == node->signature);
 178         addr_match = link && !memcmp(&link->media_addr, &maddr, sizeof(maddr));
 179         link_up = link && tipc_link_is_up(link);
 180
 181
 182         /* These three flags give us eight permutations: */
 183
 184         if (sign_match && addr_match && link_up) {
 185                 /* All is fine. Do nothing. */
 186         } else if (sign_match && addr_match && !link_up) {
 187                 /* Respond. The link will come up in due time */
 188                 respond = true;
 189         } else if (sign_match && !addr_match && link_up) {
 190                 /* Peer has changed i/f address without rebooting.
 191                  * If so, the link will reset soon, and the next
 192                  * discovery will be accepted. So we can ignore it.
 193                  * It may also be an cloned or malicious peer having
 194                  * chosen the same node address and signature as an
 195                  * existing one.
 196                  * Ignore requests until the link goes down, if ever.
 197                  */
 198                 disc_dupl_alert(bearer, onode, &maddr);
 199         } else if (sign_match && !addr_match && !link_up) {
 200                 /* Peer link has changed i/f address without rebooting.
 201                  * It may also be a cloned or malicious peer; we can't
 202                  * distinguish between the two.
 203                  * The signature is correct, so we must accept.
 204                  */
 205                 accept_addr = true;
 206                 respond = true;
 207         } else if (!sign_match && addr_match && link_up) {
 208                 /* Peer node rebooted. Two possibilities:
 209                  *  - Delayed re-discovery; this link endpoint has already
 210                  *    reset and re-established contact with the peer, before
 211                  *    receiving a discovery message from that node.
 212                  *    (The peer happened to receive one from this node first).
 213                  *  - The peer came back so fast that our side has not
 214                  *    discovered it yet. Probing from this side will soon
 215                  *    reset the link, since there can be no working link
 216                  *    endpoint at the peer end, and the link will re-establish.
 217                  *  Accept the signature, since it comes from a known peer.
 218                  */
 219                 accept_sign = true;
 220         } else if (!sign_match && addr_match && !link_up) {
 221                 /*  The peer node has rebooted.
 222                  *  Accept signature, since it is a known peer.
 223                  */
 224                 accept_sign = true;
 225                 respond = true;
 226         } else if (!sign_match && !addr_match && link_up) {
 227                 /* Peer rebooted with new address, or a new/duplicate peer.
 228                  * Ignore until the link goes down, if ever.
 229                  */
 230                 disc_dupl_alert(bearer, onode, &maddr);
 231         } else if (!sign_match && !addr_match && !link_up) {
 232                 /* Peer rebooted with new address, or it is a new peer.
 233                  * Accept signature and address.
 234                 */
 235                 accept_sign = true;
 236                 accept_addr = true;
 237                 respond = true;
 238         }
 239
 240         if (accept_sign)
 241                 node->signature = signature;
 242
 243         if (accept_addr) {
 244                 if (!link)
 245                         link = tipc_link_create(node, bearer, &maddr);
 246                 if (link) {
 247                         memcpy(&link->media_addr, &maddr, sizeof(maddr));
 248                         tipc_link_reset(link);
 249                 } else {
 250                         respond = false;
 251                 }
 252         }
 253
 254         /* Send response, if necessary */
 255         if (respond && (mtyp == DSC_REQ_MSG)) {
 256                 rbuf = tipc_buf_acquire(INT_H_SIZE);
 257                 if (rbuf) {
 258                         tipc_disc_init_msg(net, rbuf, DSC_RESP_MSG, bearer);
 259                         tipc_bearer_send(net, bearer->identity, rbuf, &maddr);
 260                         kfree_skb(rbuf);
 261                 }
 262         }
 263         tipc_node_unlock(node);
 264 }
 265
 266 /**
 267  * disc_update - update frequency of periodic link setup requests
 268  * @req: ptr to link request structure
 269  *
 270  * Reinitiates discovery process if discovery object has no associated nodes
 271  * and is either not currently searching or is searching at a slow rate
 272  */
 273 static void disc_update(struct tipc_link_req *req)
 274 {
 275         if (!req->num_nodes) {
 276                 if ((req->timer_intv == TIPC_LINK_REQ_INACTIVE) ||
 277                     (req->timer_intv > TIPC_LINK_REQ_FAST)) {
 278                         req->timer_intv = TIPC_LINK_REQ_INIT;
 279                         mod_timer(&req->timer, jiffies + req->timer_intv);
 280                 }
 281         }
 282 }
 283
 284 /**
 285  * tipc_disc_add_dest - increment set of discovered nodes
 286  * @req: ptr to link request structure
 287  */
 288 void tipc_disc_add_dest(struct tipc_link_req *req)
 289 {
 290         spin_lock_bh(&req->lock);
 291         req->num_nodes++;
 292         spin_unlock_bh(&req->lock);
 293 }
 294
 295 /**
 296  * tipc_disc_remove_dest - decrement set of discovered nodes
 297  * @req: ptr to link request structure
 298  */
 299 void tipc_disc_remove_dest(struct tipc_link_req *req)
 300 {
 301         spin_lock_bh(&req->lock);
 302         req->num_nodes--;
 303         disc_update(req);
 304         spin_unlock_bh(&req->lock);
 305 }
 306
 307 /**
 308  * disc_timeout - send a periodic link setup request
 309  * @data: ptr to link request structure
 310  *
 311  * Called whenever a link setup request timer associated with a bearer expires.
 312  */
 313 static void disc_timeout(unsigned long data)
 314 {
 315         struct tipc_link_req *req = (struct tipc_link_req *)data;
 316         int max_delay;
 317
 318         spin_lock_bh(&req->lock);
 319
 320         /* Stop searching if only desired node has been found */
 321         if (tipc_node(req->domain) && req->num_nodes) {
 322                 req->timer_intv = TIPC_LINK_REQ_INACTIVE;
 323                 goto exit;
 324         }
 325
 326         /*
 327          * Send discovery message, then update discovery timer
 328          *
 329          * Keep doubling time between requests until limit is reached;
 330          * hold at fast polling rate if don't have any associated nodes,
 331          * otherwise hold at slow polling rate
 332          */
 333         tipc_bearer_send(req->net, req->bearer_id, req->buf, &req->dest);
 334
 335
 336         req->timer_intv *= 2;
 337         if (req->num_nodes)
 338                 max_delay = TIPC_LINK_REQ_SLOW;
 339         else
 340                 max_delay = TIPC_LINK_REQ_FAST;
 341         if (req->timer_intv > max_delay)
 342                 req->timer_intv = max_delay;
 343
 344         mod_timer(&req->timer, jiffies + req->timer_intv);
 345 exit:
 346         spin_unlock_bh(&req->lock);
 347 }
 348
 349 /**
 350  * tipc_disc_create - create object to send periodic link setup requests
 351  * @net: the applicable net namespace
 352  * @b_ptr: ptr to bearer issuing requests
 353  * @dest: destination address for request messages
 354  * @dest_domain: network domain to which links can be established
 355  *
 356  * Returns 0 if successful, otherwise -errno.
 357  */
 358 int tipc_disc_create(struct net *net, struct tipc_bearer *b_ptr,
 359                      struct tipc_media_addr *dest)
 360 {
 361         struct tipc_link_req *req;
 362
 363         req = kmalloc(sizeof(*req), GFP_ATOMIC);
 364         if (!req)
 365                 return -ENOMEM;
 366
 367         req->buf = tipc_buf_acquire(INT_H_SIZE);
 368         if (!req->buf) {
 369                 kfree(req);
 370                 return -ENOMEM;
 371         }
 372
 373         tipc_disc_init_msg(net, req->buf, DSC_REQ_MSG, b_ptr);
 374         memcpy(&req->dest, dest, sizeof(*dest));
 375         req->net = net;
 376         req->bearer_id = b_ptr->identity;
 377         req->domain = b_ptr->domain;
 378         req->num_nodes = 0;
 379         req->timer_intv = TIPC_LINK_REQ_INIT;
 380         spin_lock_init(&req->lock);
 381         setup_timer(&req->timer, disc_timeout, (unsigned long)req);
 382         mod_timer(&req->timer, jiffies + req->timer_intv);
 383         b_ptr->link_req = req;
 384         tipc_bearer_send(net, req->bearer_id, req->buf, &req->dest);
 385         return 0;
 386 }
 387
 388 /**
 389  * tipc_disc_delete - destroy object sending periodic link setup requests
 390  * @req: ptr to link request structure
 391  */
 392 void tipc_disc_delete(struct tipc_link_req *req)
 393 {
 394         del_timer_sync(&req->timer);
 395         kfree_skb(req->buf);
 396         kfree(req);
 397 }
 398
 399 /**
 400  * tipc_disc_reset - reset object to send periodic link setup requests
 401  * @net: the applicable net namespace
 402  * @b_ptr: ptr to bearer issuing requests
 403  * @dest_domain: network domain to which links can be established
 404  */
 405 void tipc_disc_reset(struct net *net, struct tipc_bearer *b_ptr)
 406 {
 407         struct tipc_link_req *req = b_ptr->link_req;
 408
 409         spin_lock_bh(&req->lock);
 410         tipc_disc_init_msg(net, req->buf, DSC_REQ_MSG, b_ptr);
 411         req->net = net;
 412         req->bearer_id = b_ptr->identity;
 413         req->domain = b_ptr->domain;
 414         req->num_nodes = 0;
 415         req->timer_intv = TIPC_LINK_REQ_INIT;
 416         mod_timer(&req->timer, jiffies + req->timer_intv);
 417         tipc_bearer_send(net, req->bearer_id, req->buf, &req->dest);
 418         spin_unlock_bh(&req->lock);
 419 }