net/tipc/net.c

   1 /*
   2  * net/tipc/net.c: TIPC network routing code
   3  *
   4  * Copyright (c) 1995-2006, 2014, Ericsson AB
   5  * Copyright (c) 2005, 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 "net.h"
  39 #include "name_distr.h"
  40 #include "subscr.h"
  41 #include "socket.h"
  42 #include "node.h"
  43 #include "config.h"
  44
  45 static const struct nla_policy tipc_nl_net_policy[TIPC_NLA_NET_MAX + 1] = {
  46         [TIPC_NLA_NET_UNSPEC]   = { .type = NLA_UNSPEC },
  47         [TIPC_NLA_NET_ID]       = { .type = NLA_U32 }
  48 };
  49
  50 /*
  51  * The TIPC locking policy is designed to ensure a very fine locking
  52  * granularity, permitting complete parallel access to individual
  53  * port and node/link instances. The code consists of four major
  54  * locking domains, each protected with their own disjunct set of locks.
  55  *
  56  * 1: The bearer level.
  57  *    RTNL lock is used to serialize the process of configuring bearer
  58  *    on update side, and RCU lock is applied on read side to make
  59  *    bearer instance valid on both paths of message transmission and
  60  *    reception.
  61  *
  62  * 2: The node and link level.
  63  *    All node instances are saved into two tipc_node_list and node_htable
  64  *    lists. The two lists are protected by node_list_lock on write side,
  65  *    and they are guarded with RCU lock on read side. Especially node
  66  *    instance is destroyed only when TIPC module is removed, and we can
  67  *    confirm that there has no any user who is accessing the node at the
  68  *    moment. Therefore, Except for iterating the two lists within RCU
  69  *    protection, it's no needed to hold RCU that we access node instance
  70  *    in other places.
  71  *
  72  *    In addition, all members in node structure including link instances
  73  *    are protected by node spin lock.
  74  *
  75  * 3: The transport level of the protocol.
  76  *    This consists of the structures port, (and its user level
  77  *    representations, such as user_port and tipc_sock), reference and
  78  *    tipc_user (port.c, reg.c, socket.c).
  79  *
  80  *    This layer has four different locks:
  81  *     - The tipc_port spin_lock. This is protecting each port instance
  82  *       from parallel data access and removal. Since we can not place
  83  *       this lock in the port itself, it has been placed in the
  84  *       corresponding reference table entry, which has the same life
  85  *       cycle as the module. This entry is difficult to access from
  86  *       outside the TIPC core, however, so a pointer to the lock has
  87  *       been added in the port instance, -to be used for unlocking
  88  *       only.
  89  *     - A read/write lock to protect the reference table itself (teg.c).
  90  *       (Nobody is using read-only access to this, so it can just as
  91  *       well be changed to a spin_lock)
  92  *     - A spin lock to protect the registry of kernel/driver users (reg.c)
  93  *     - A global spin_lock (tipc_port_lock), which only task is to ensure
  94  *       consistency where more than one port is involved in an operation,
  95  *       i.e., whe a port is part of a linked list of ports.
  96  *       There are two such lists; 'port_list', which is used for management,
  97  *       and 'wait_list', which is used to queue ports during congestion.
  98  *
  99  *  4: The name table (name_table.c, name_distr.c, subscription.c)
 100  *     - There is one big read/write-lock (tipc_nametbl_lock) protecting the
 101  *       overall name table structure. Nothing must be added/removed to
 102  *       this structure without holding write access to it.
 103  *     - There is one local spin_lock per sub_sequence, which can be seen
 104  *       as a sub-domain to the tipc_nametbl_lock domain. It is used only
 105  *       for translation operations, and is needed because a translation
 106  *       steps the root of the 'publication' linked list between each lookup.
 107  *       This is always used within the scope of a tipc_nametbl_lock(read).
 108  *     - A local spin_lock protecting the queue of subscriber events.
 109 */
 110
 111 int tipc_net_start(u32 addr)
 112 {
 113         char addr_string[16];
 114         int res;
 115
 116         tipc_own_addr = addr;
 117         tipc_named_reinit();
 118         tipc_sk_reinit();
 119         res = tipc_bclink_init();
 120         if (res)
 121                 return res;
 122
 123         tipc_nametbl_publish(TIPC_CFG_SRV, tipc_own_addr, tipc_own_addr,
 124                              TIPC_ZONE_SCOPE, 0, tipc_own_addr);
 125
 126         pr_info("Started in network mode\n");
 127         pr_info("Own node address %s, network identity %u\n",
 128                 tipc_addr_string_fill(addr_string, tipc_own_addr), tipc_net_id);
 129         return 0;
 130 }
 131
 132 void tipc_net_stop(void)
 133 {
 134         if (!tipc_own_addr)
 135                 return;
 136
 137         tipc_nametbl_withdraw(TIPC_CFG_SRV, tipc_own_addr, 0, tipc_own_addr);
 138         rtnl_lock();
 139         tipc_bearer_stop();
 140         tipc_bclink_stop();
 141         tipc_node_stop();
 142         rtnl_unlock();
 143
 144         pr_info("Left network mode\n");
 145 }
 146
 147 static int __tipc_nl_add_net(struct tipc_nl_msg *msg)
 148 {
 149         void *hdr;
 150         struct nlattr *attrs;
 151
 152         hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_v2_family,
 153                           NLM_F_MULTI, TIPC_NL_NET_GET);
 154         if (!hdr)
 155                 return -EMSGSIZE;
 156
 157         attrs = nla_nest_start(msg->skb, TIPC_NLA_NET);
 158         if (!attrs)
 159                 goto msg_full;
 160
 161         if (nla_put_u32(msg->skb, TIPC_NLA_NET_ID, tipc_net_id))
 162                 goto attr_msg_full;
 163
 164         nla_nest_end(msg->skb, attrs);
 165         genlmsg_end(msg->skb, hdr);
 166
 167         return 0;
 168
 169 attr_msg_full:
 170         nla_nest_cancel(msg->skb, attrs);
 171 msg_full:
 172         genlmsg_cancel(msg->skb, hdr);
 173
 174         return -EMSGSIZE;
 175 }
 176
 177 int tipc_nl_net_dump(struct sk_buff *skb, struct netlink_callback *cb)
 178 {
 179         int err;
 180         int done = cb->args[0];
 181         struct tipc_nl_msg msg;
 182
 183         if (done)
 184                 return 0;
 185
 186         msg.skb = skb;
 187         msg.portid = NETLINK_CB(cb->skb).portid;
 188         msg.seq = cb->nlh->nlmsg_seq;
 189
 190         err = __tipc_nl_add_net(&msg);
 191         if (err)
 192                 goto out;
 193
 194         done = 1;
 195 out:
 196         cb->args[0] = done;
 197
 198         return skb->len;
 199 }
 200
 201 int tipc_nl_net_set(struct sk_buff *skb, struct genl_info *info)
 202 {
 203         int err;
 204         struct nlattr *attrs[TIPC_NLA_NET_MAX + 1];
 205
 206         if (!info->attrs[TIPC_NLA_NET])
 207                 return -EINVAL;
 208
 209         err = nla_parse_nested(attrs, TIPC_NLA_NET_MAX,
 210                                info->attrs[TIPC_NLA_NET],
 211                                tipc_nl_net_policy);
 212         if (err)
 213                 return err;
 214
 215         if (attrs[TIPC_NLA_NET_ID]) {
 216                 u32 val;
 217
 218                 /* Can't change net id once TIPC has joined a network */
 219                 if (tipc_own_addr)
 220                         return -EPERM;
 221
 222                 val = nla_get_u32(attrs[TIPC_NLA_NET_ID]);
 223                 if (val < 1 || val > 9999)
 224                         return -EINVAL;
 225
 226                 tipc_net_id = val;
 227         }
 228
 229         if (attrs[TIPC_NLA_NET_ADDR]) {
 230                 u32 addr;
 231
 232                 /* Can't change net addr once TIPC has joined a network */
 233                 if (tipc_own_addr)
 234                         return -EPERM;
 235
 236                 addr = nla_get_u32(attrs[TIPC_NLA_NET_ADDR]);
 237                 if (!tipc_addr_node_valid(addr))
 238                         return -EINVAL;
 239
 240                 rtnl_lock();
 241                 tipc_net_start(addr);
 242                 rtnl_unlock();
 243         }
 244
 245         return 0;
 246 }