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