linux/net/rds/bind.c
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   1/*
   2 * Copyright (c) 2006 Oracle.  All rights reserved.
   3 *
   4 * This software is available to you under a choice of one of two
   5 * licenses.  You may choose to be licensed under the terms of the GNU
   6 * General Public License (GPL) Version 2, available from the file
   7 * COPYING in the main directory of this source tree, or the
   8 * OpenIB.org BSD license below:
   9 *
  10 *     Redistribution and use in source and binary forms, with or
  11 *     without modification, are permitted provided that the following
  12 *     conditions are met:
  13 *
  14 *      - Redistributions of source code must retain the above
  15 *        copyright notice, this list of conditions and the following
  16 *        disclaimer.
  17 *
  18 *      - Redistributions in binary form must reproduce the above
  19 *        copyright notice, this list of conditions and the following
  20 *        disclaimer in the documentation and/or other materials
  21 *        provided with the distribution.
  22 *
  23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
  27 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
  29 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  30 * SOFTWARE.
  31 *
  32 */
  33#include <linux/kernel.h>
  34#include <net/sock.h>
  35#include <linux/in.h>
  36#include <linux/if_arp.h>
  37#include <linux/jhash.h>
  38#include <linux/ratelimit.h>
  39#include "rds.h"
  40
  41#define BIND_HASH_SIZE 1024
  42static struct hlist_head bind_hash_table[BIND_HASH_SIZE];
  43static DEFINE_SPINLOCK(rds_bind_lock);
  44
  45static struct hlist_head *hash_to_bucket(__be32 addr, __be16 port)
  46{
  47        return bind_hash_table + (jhash_2words((u32)addr, (u32)port, 0) &
  48                                  (BIND_HASH_SIZE - 1));
  49}
  50
  51static struct rds_sock *rds_bind_lookup(__be32 addr, __be16 port,
  52                                        struct rds_sock *insert)
  53{
  54        struct rds_sock *rs;
  55        struct hlist_node *node;
  56        struct hlist_head *head = hash_to_bucket(addr, port);
  57        u64 cmp;
  58        u64 needle = ((u64)be32_to_cpu(addr) << 32) | be16_to_cpu(port);
  59
  60        rcu_read_lock();
  61        hlist_for_each_entry_rcu(rs, node, head, rs_bound_node) {
  62                cmp = ((u64)be32_to_cpu(rs->rs_bound_addr) << 32) |
  63                      be16_to_cpu(rs->rs_bound_port);
  64
  65                if (cmp == needle) {
  66                        rcu_read_unlock();
  67                        return rs;
  68                }
  69        }
  70        rcu_read_unlock();
  71
  72        if (insert) {
  73                /*
  74                 * make sure our addr and port are set before
  75                 * we are added to the list, other people
  76                 * in rcu will find us as soon as the
  77                 * hlist_add_head_rcu is done
  78                 */
  79                insert->rs_bound_addr = addr;
  80                insert->rs_bound_port = port;
  81                rds_sock_addref(insert);
  82
  83                hlist_add_head_rcu(&insert->rs_bound_node, head);
  84        }
  85        return NULL;
  86}
  87
  88/*
  89 * Return the rds_sock bound at the given local address.
  90 *
  91 * The rx path can race with rds_release.  We notice if rds_release() has
  92 * marked this socket and don't return a rs ref to the rx path.
  93 */
  94struct rds_sock *rds_find_bound(__be32 addr, __be16 port)
  95{
  96        struct rds_sock *rs;
  97
  98        rs = rds_bind_lookup(addr, port, NULL);
  99
 100        if (rs && !sock_flag(rds_rs_to_sk(rs), SOCK_DEAD))
 101                rds_sock_addref(rs);
 102        else
 103                rs = NULL;
 104
 105        rdsdebug("returning rs %p for %pI4:%u\n", rs, &addr,
 106                ntohs(port));
 107        return rs;
 108}
 109
 110/* returns -ve errno or +ve port */
 111static int rds_add_bound(struct rds_sock *rs, __be32 addr, __be16 *port)
 112{
 113        unsigned long flags;
 114        int ret = -EADDRINUSE;
 115        u16 rover, last;
 116
 117        if (*port != 0) {
 118                rover = be16_to_cpu(*port);
 119                last = rover;
 120        } else {
 121                rover = max_t(u16, net_random(), 2);
 122                last = rover - 1;
 123        }
 124
 125        spin_lock_irqsave(&rds_bind_lock, flags);
 126
 127        do {
 128                if (rover == 0)
 129                        rover++;
 130                if (!rds_bind_lookup(addr, cpu_to_be16(rover), rs)) {
 131                        *port = rs->rs_bound_port;
 132                        ret = 0;
 133                        rdsdebug("rs %p binding to %pI4:%d\n",
 134                          rs, &addr, (int)ntohs(*port));
 135                        break;
 136                }
 137        } while (rover++ != last);
 138
 139        spin_unlock_irqrestore(&rds_bind_lock, flags);
 140
 141        return ret;
 142}
 143
 144void rds_remove_bound(struct rds_sock *rs)
 145{
 146        unsigned long flags;
 147
 148        spin_lock_irqsave(&rds_bind_lock, flags);
 149
 150        if (rs->rs_bound_addr) {
 151                rdsdebug("rs %p unbinding from %pI4:%d\n",
 152                  rs, &rs->rs_bound_addr,
 153                  ntohs(rs->rs_bound_port));
 154
 155                hlist_del_init_rcu(&rs->rs_bound_node);
 156                rds_sock_put(rs);
 157                rs->rs_bound_addr = 0;
 158        }
 159
 160        spin_unlock_irqrestore(&rds_bind_lock, flags);
 161}
 162
 163int rds_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len)
 164{
 165        struct sock *sk = sock->sk;
 166        struct sockaddr_in *sin = (struct sockaddr_in *)uaddr;
 167        struct rds_sock *rs = rds_sk_to_rs(sk);
 168        struct rds_transport *trans;
 169        int ret = 0;
 170
 171        lock_sock(sk);
 172
 173        if (addr_len != sizeof(struct sockaddr_in) ||
 174            sin->sin_family != AF_INET ||
 175            rs->rs_bound_addr ||
 176            sin->sin_addr.s_addr == htonl(INADDR_ANY)) {
 177                ret = -EINVAL;
 178                goto out;
 179        }
 180
 181        ret = rds_add_bound(rs, sin->sin_addr.s_addr, &sin->sin_port);
 182        if (ret)
 183                goto out;
 184
 185        trans = rds_trans_get_preferred(sin->sin_addr.s_addr);
 186        if (!trans) {
 187                ret = -EADDRNOTAVAIL;
 188                rds_remove_bound(rs);
 189                printk_ratelimited(KERN_INFO "RDS: rds_bind() could not find a transport, "
 190                                "load rds_tcp or rds_rdma?\n");
 191                goto out;
 192        }
 193
 194        rs->rs_transport = trans;
 195        ret = 0;
 196
 197out:
 198        release_sock(sk);
 199
 200        /* we might have called rds_remove_bound on error */
 201        if (ret)
 202                synchronize_rcu();
 203        return ret;
 204}
 205
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