git.oblomov.eu Git - linux-2.6/blob - net/ipv4/inet_connection_sock.c

   1 /*
   2  * INET         An implementation of the TCP/IP protocol suite for the LINUX
   3  *              operating system.  INET is implemented using the  BSD Socket
   4  *              interface as the means of communication with the user level.
   5  *
   6  *              Support for INET connection oriented protocols.
   7  *
   8  * Authors:     See the TCP sources
   9  *
  10  *              This program is free software; you can redistribute it and/or
  11  *              modify it under the terms of the GNU General Public License
  12  *              as published by the Free Software Foundation; either version
  13  *              2 of the License, or(at your option) any later version.
  14  */
  15
  16 #include <linux/config.h>
  17 #include <linux/module.h>
  18 #include <linux/jhash.h>
  19
  20 #include <net/inet_connection_sock.h>
  21 #include <net/inet_hashtables.h>
  22 #include <net/inet_timewait_sock.h>
  23 #include <net/ip.h>
  24 #include <net/route.h>
  25 #include <net/tcp_states.h>
  26
  27 #ifdef INET_CSK_DEBUG
  28 const char inet_csk_timer_bug_msg[] = "inet_csk BUG: unknown timer value\n";
  29 EXPORT_SYMBOL(inet_csk_timer_bug_msg);
  30 #endif
  31
  32 /*
  33  * This array holds the first and last local port number.
  34  * For high-usage systems, use sysctl to change this to
  35  * 32768-61000
  36  */
  37 int sysctl_local_port_range[2] = { 1024, 4999 };
  38
  39 static inline int inet_csk_bind_conflict(struct sock *sk, struct inet_bind_bucket *tb)
  40 {
  41         const u32 sk_rcv_saddr = inet_rcv_saddr(sk);
  42         struct sock *sk2;
  43         struct hlist_node *node;
  44         int reuse = sk->sk_reuse;
  45
  46         sk_for_each_bound(sk2, node, &tb->owners) {
  47                 if (sk != sk2 &&
  48                     !inet_v6_ipv6only(sk2) &&
  49                     (!sk->sk_bound_dev_if ||
  50                      !sk2->sk_bound_dev_if ||
  51                      sk->sk_bound_dev_if == sk2->sk_bound_dev_if)) {
  52                         if (!reuse || !sk2->sk_reuse ||
  53                             sk2->sk_state == TCP_LISTEN) {
  54                                 const u32 sk2_rcv_saddr = inet_rcv_saddr(sk2);
  55                                 if (!sk2_rcv_saddr || !sk_rcv_saddr ||
  56                                     sk2_rcv_saddr == sk_rcv_saddr)
  57                                         break;
  58                         }
  59                 }
  60         }
  61         return node != NULL;
  62 }
  63
  64 /* Obtain a reference to a local port for the given sock,
  65  * if snum is zero it means select any available local port.
  66  */
  67 int inet_csk_get_port(struct inet_hashinfo *hashinfo,
  68                       struct sock *sk, unsigned short snum)
  69 {
  70         struct inet_bind_hashbucket *head;
  71         struct hlist_node *node;
  72         struct inet_bind_bucket *tb;
  73         int ret;
  74
  75         local_bh_disable();
  76         if (!snum) {
  77                 int low = sysctl_local_port_range[0];
  78                 int high = sysctl_local_port_range[1];
  79                 int remaining = (high - low) + 1;
  80                 int rover;
  81
  82                 spin_lock(&hashinfo->portalloc_lock);
  83                 if (hashinfo->port_rover < low)
  84                         rover = low;
  85                 else
  86                         rover = hashinfo->port_rover;
  87                 do {
  88                         rover++;
  89                         if (rover > high)
  90                                 rover = low;
  91                         head = &hashinfo->bhash[inet_bhashfn(rover, hashinfo->bhash_size)];
  92                         spin_lock(&head->lock);
  93                         inet_bind_bucket_for_each(tb, node, &head->chain)
  94                                 if (tb->port == rover)
  95                                         goto next;
  96                         break;
  97                 next:
  98                         spin_unlock(&head->lock);
  99                 } while (--remaining > 0);
 100                 hashinfo->port_rover = rover;
 101                 spin_unlock(&hashinfo->portalloc_lock);
 102
 103                 /* Exhausted local port range during search?  It is not
 104                  * possible for us to be holding one of the bind hash
 105                  * locks if this test triggers, because if 'remaining'
 106                  * drops to zero, we broke out of the do/while loop at
 107                  * the top level, not from the 'break;' statement.
 108                  */
 109                 ret = 1;
 110                 if (remaining <= 0)
 111                         goto fail;
 112
 113                 /* OK, here is the one we will use.  HEAD is
 114                  * non-NULL and we hold it's mutex.
 115                  */
 116                 snum = rover;
 117         } else {
 118                 head = &hashinfo->bhash[inet_bhashfn(snum, hashinfo->bhash_size)];
 119                 spin_lock(&head->lock);
 120                 inet_bind_bucket_for_each(tb, node, &head->chain)
 121                         if (tb->port == snum)
 122                                 goto tb_found;
 123         }
 124         tb = NULL;
 125         goto tb_not_found;
 126 tb_found:
 127         if (!hlist_empty(&tb->owners)) {
 128                 if (sk->sk_reuse > 1)
 129                         goto success;
 130                 if (tb->fastreuse > 0 &&
 131                     sk->sk_reuse && sk->sk_state != TCP_LISTEN) {
 132                         goto success;
 133                 } else {
 134                         ret = 1;
 135                         if (inet_csk_bind_conflict(sk, tb))
 136                                 goto fail_unlock;
 137                 }
 138         }
 139 tb_not_found:
 140         ret = 1;
 141         if (!tb && (tb = inet_bind_bucket_create(hashinfo->bind_bucket_cachep, head, snum)) == NULL)
 142                 goto fail_unlock;
 143         if (hlist_empty(&tb->owners)) {
 144                 if (sk->sk_reuse && sk->sk_state != TCP_LISTEN)
 145                         tb->fastreuse = 1;
 146                 else
 147                         tb->fastreuse = 0;
 148         } else if (tb->fastreuse &&
 149                    (!sk->sk_reuse || sk->sk_state == TCP_LISTEN))
 150                 tb->fastreuse = 0;
 151 success:
 152         if (!inet_csk(sk)->icsk_bind_hash)
 153                 inet_bind_hash(sk, tb, snum);
 154         BUG_TRAP(inet_csk(sk)->icsk_bind_hash == tb);
 155         ret = 0;
 156
 157 fail_unlock:
 158         spin_unlock(&head->lock);
 159 fail:
 160         local_bh_enable();
 161         return ret;
 162 }
 163
 164 EXPORT_SYMBOL_GPL(inet_csk_get_port);
 165
 166 /*
 167  * Wait for an incoming connection, avoid race conditions. This must be called
 168  * with the socket locked.
 169  */
 170 static int inet_csk_wait_for_connect(struct sock *sk, long timeo)
 171 {
 172         struct inet_connection_sock *icsk = inet_csk(sk);
 173         DEFINE_WAIT(wait);
 174         int err;
 175
 176         /*
 177          * True wake-one mechanism for incoming connections: only
 178          * one process gets woken up, not the 'whole herd'.
 179          * Since we do not 'race & poll' for established sockets
 180          * anymore, the common case will execute the loop only once.
 181          *
 182          * Subtle issue: "add_wait_queue_exclusive()" will be added
 183          * after any current non-exclusive waiters, and we know that
 184          * it will always _stay_ after any new non-exclusive waiters
 185          * because all non-exclusive waiters are added at the
 186          * beginning of the wait-queue. As such, it's ok to "drop"
 187          * our exclusiveness temporarily when we get woken up without
 188          * having to remove and re-insert us on the wait queue.
 189          */
 190         for (;;) {
 191                 prepare_to_wait_exclusive(sk->sk_sleep, &wait,
 192                                           TASK_INTERRUPTIBLE);
 193                 release_sock(sk);
 194                 if (reqsk_queue_empty(&icsk->icsk_accept_queue))
 195                         timeo = schedule_timeout(timeo);
 196                 lock_sock(sk);
 197                 err = 0;
 198                 if (!reqsk_queue_empty(&icsk->icsk_accept_queue))
 199                         break;
 200                 err = -EINVAL;
 201                 if (sk->sk_state != TCP_LISTEN)
 202                         break;
 203                 err = sock_intr_errno(timeo);
 204                 if (signal_pending(current))
 205                         break;
 206                 err = -EAGAIN;
 207                 if (!timeo)
 208                         break;
 209         }
 210         finish_wait(sk->sk_sleep, &wait);
 211         return err;
 212 }
 213
 214 /*
 215  * This will accept the next outstanding connection.
 216  */
 217 struct sock *inet_csk_accept(struct sock *sk, int flags, int *err)
 218 {
 219         struct inet_connection_sock *icsk = inet_csk(sk);
 220         struct sock *newsk;
 221         int error;
 222
 223         lock_sock(sk);
 224
 225         /* We need to make sure that this socket is listening,
 226          * and that it has something pending.
 227          */
 228         error = -EINVAL;
 229         if (sk->sk_state != TCP_LISTEN)
 230                 goto out_err;
 231
 232         /* Find already established connection */
 233         if (reqsk_queue_empty(&icsk->icsk_accept_queue)) {
 234                 long timeo = sock_rcvtimeo(sk, flags & O_NONBLOCK);
 235
 236                 /* If this is a non blocking socket don't sleep */
 237                 error = -EAGAIN;
 238                 if (!timeo)
 239                         goto out_err;
 240
 241                 error = inet_csk_wait_for_connect(sk, timeo);
 242                 if (error)
 243                         goto out_err;
 244         }
 245
 246         newsk = reqsk_queue_get_child(&icsk->icsk_accept_queue, sk);
 247         BUG_TRAP(newsk->sk_state != TCP_SYN_RECV);
 248 out:
 249         release_sock(sk);
 250         return newsk;
 251 out_err:
 252         newsk = NULL;
 253         *err = error;
 254         goto out;
 255 }
 256
 257 EXPORT_SYMBOL(inet_csk_accept);
 258
 259 /*
 260  * Using different timers for retransmit, delayed acks and probes
 261  * We may wish use just one timer maintaining a list of expire jiffies
 262  * to optimize.
 263  */
 264 void inet_csk_init_xmit_timers(struct sock *sk,
 265                                void (*retransmit_handler)(unsigned long),
 266                                void (*delack_handler)(unsigned long),
 267                                void (*keepalive_handler)(unsigned long))
 268 {
 269         struct inet_connection_sock *icsk = inet_csk(sk);
 270
 271         init_timer(&icsk->icsk_retransmit_timer);
 272         init_timer(&icsk->icsk_delack_timer);
 273         init_timer(&sk->sk_timer);
 274
 275         icsk->icsk_retransmit_timer.function = retransmit_handler;
 276         icsk->icsk_delack_timer.function     = delack_handler;
 277         sk->sk_timer.function                = keepalive_handler;
 278
 279         icsk->icsk_retransmit_timer.data =
 280                 icsk->icsk_delack_timer.data =
 281                         sk->sk_timer.data  = (unsigned long)sk;
 282
 283         icsk->icsk_pending = icsk->icsk_ack.pending = 0;
 284 }
 285
 286 EXPORT_SYMBOL(inet_csk_init_xmit_timers);
 287
 288 void inet_csk_clear_xmit_timers(struct sock *sk)
 289 {
 290         struct inet_connection_sock *icsk = inet_csk(sk);
 291
 292         icsk->icsk_pending = icsk->icsk_ack.pending = icsk->icsk_ack.blocked = 0;
 293
 294         sk_stop_timer(sk, &icsk->icsk_retransmit_timer);
 295         sk_stop_timer(sk, &icsk->icsk_delack_timer);
 296         sk_stop_timer(sk, &sk->sk_timer);
 297 }
 298
 299 EXPORT_SYMBOL(inet_csk_clear_xmit_timers);
 300
 301 void inet_csk_delete_keepalive_timer(struct sock *sk)
 302 {
 303         sk_stop_timer(sk, &sk->sk_timer);
 304 }
 305
 306 EXPORT_SYMBOL(inet_csk_delete_keepalive_timer);
 307
 308 void inet_csk_reset_keepalive_timer(struct sock *sk, unsigned long len)
 309 {
 310         sk_reset_timer(sk, &sk->sk_timer, jiffies + len);
 311 }
 312
 313 EXPORT_SYMBOL(inet_csk_reset_keepalive_timer);
 314
 315 struct dst_entry* inet_csk_route_req(struct sock *sk,
 316                                      const struct request_sock *req)
 317 {
 318         struct rtable *rt;
 319         const struct inet_request_sock *ireq = inet_rsk(req);
 320         struct ip_options *opt = inet_rsk(req)->opt;
 321         struct flowi fl = { .oif = sk->sk_bound_dev_if,
 322                             .nl_u = { .ip4_u =
 323                                       { .daddr = ((opt && opt->srr) ?
 324                                                   opt->faddr :
 325                                                   ireq->rmt_addr),
 326                                         .saddr = ireq->loc_addr,
 327                                         .tos = RT_CONN_FLAGS(sk) } },
 328                             .proto = sk->sk_protocol,
 329                             .uli_u = { .ports =
 330                                        { .sport = inet_sk(sk)->sport,
 331                                          .dport = ireq->rmt_port } } };
 332
 333         if (ip_route_output_flow(&rt, &fl, sk, 0)) {
 334                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
 335                 return NULL;
 336         }
 337         if (opt && opt->is_strictroute && rt->rt_dst != rt->rt_gateway) {
 338                 ip_rt_put(rt);
 339                 IP_INC_STATS_BH(IPSTATS_MIB_OUTNOROUTES);
 340                 return NULL;
 341         }
 342         return &rt->u.dst;
 343 }
 344
 345 EXPORT_SYMBOL_GPL(inet_csk_route_req);
 346
 347 static inline u32 inet_synq_hash(const u32 raddr, const u16 rport,
 348                                  const u32 rnd, const u16 synq_hsize)
 349 {
 350         return jhash_2words(raddr, (u32)rport, rnd) & (synq_hsize - 1);
 351 }
 352
 353 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 354 #define AF_INET_FAMILY(fam) ((fam) == AF_INET)
 355 #else
 356 #define AF_INET_FAMILY(fam) 1
 357 #endif
 358
 359 struct request_sock *inet_csk_search_req(const struct sock *sk,
 360                                          struct request_sock ***prevp,
 361                                          const __u16 rport, const __u32 raddr,
 362                                          const __u32 laddr)
 363 {
 364         const struct inet_connection_sock *icsk = inet_csk(sk);
 365         struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
 366         struct request_sock *req, **prev;
 367
 368         for (prev = &lopt->syn_table[inet_synq_hash(raddr, rport, lopt->hash_rnd,
 369                                                     lopt->nr_table_entries)];
 370              (req = *prev) != NULL;
 371              prev = &req->dl_next) {
 372                 const struct inet_request_sock *ireq = inet_rsk(req);
 373
 374                 if (ireq->rmt_port == rport &&
 375                     ireq->rmt_addr == raddr &&
 376                     ireq->loc_addr == laddr &&
 377                     AF_INET_FAMILY(req->rsk_ops->family)) {
 378                         BUG_TRAP(!req->sk);
 379                         *prevp = prev;
 380                         break;
 381                 }
 382         }
 383
 384         return req;
 385 }
 386
 387 EXPORT_SYMBOL_GPL(inet_csk_search_req);
 388
 389 void inet_csk_reqsk_queue_hash_add(struct sock *sk, struct request_sock *req,
 390                                    const unsigned timeout)
 391 {
 392         struct inet_connection_sock *icsk = inet_csk(sk);
 393         struct listen_sock *lopt = icsk->icsk_accept_queue.listen_opt;
 394         const u32 h = inet_synq_hash(inet_rsk(req)->rmt_addr, inet_rsk(req)->rmt_port,
 395                                      lopt->hash_rnd, lopt->nr_table_entries);
 396
 397         reqsk_queue_hash_req(&icsk->icsk_accept_queue, h, req, timeout);
 398         inet_csk_reqsk_queue_added(sk, timeout);
 399 }
 400
 401 EXPORT_SYMBOL_GPL(inet_csk_reqsk_queue_hash_add);