net/dccp/minisocks.c

   1 /*
   2  *  net/dccp/minisocks.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/config.h>
  14 #include <linux/dccp.h>
  15 #include <linux/skbuff.h>
  16 #include <linux/timer.h>
  17
  18 #include <net/sock.h>
  19 #include <net/xfrm.h>
  20 #include <net/inet_timewait_sock.h>
  21
  22 #include "ackvec.h"
  23 #include "ccid.h"
  24 #include "dccp.h"
  25
  26 struct inet_timewait_death_row dccp_death_row = {
  27         .sysctl_max_tw_buckets = NR_FILE * 2,
  28         .period         = DCCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS,
  29         .death_lock     = SPIN_LOCK_UNLOCKED,
  30         .hashinfo       = &dccp_hashinfo,
  31         .tw_timer       = TIMER_INITIALIZER(inet_twdr_hangman, 0,
  32                                             (unsigned long)&dccp_death_row),
  33         .twkill_work    = __WORK_INITIALIZER(dccp_death_row.twkill_work,
  34                                              inet_twdr_twkill_work,
  35                                              &dccp_death_row),
  36 /* Short-time timewait calendar */
  37
  38         .twcal_hand     = -1,
  39         .twcal_timer    = TIMER_INITIALIZER(inet_twdr_twcal_tick, 0,
  40                                             (unsigned long)&dccp_death_row),
  41 };
  42
  43 void dccp_time_wait(struct sock *sk, int state, int timeo)
  44 {
  45         struct inet_timewait_sock *tw = NULL;
  46
  47         if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
  48                 tw = inet_twsk_alloc(sk, state);
  49
  50         if (tw != NULL) {
  51                 const struct inet_connection_sock *icsk = inet_csk(sk);
  52                 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  53
  54                 /* Linkage updates. */
  55                 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  56
  57                 /* Get the TIME_WAIT timeout firing. */
  58                 if (timeo < rto)
  59                         timeo = rto;
  60
  61                 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
  62                 if (state == DCCP_TIME_WAIT)
  63                         timeo = DCCP_TIMEWAIT_LEN;
  64
  65                 inet_twsk_schedule(tw, &dccp_death_row, timeo,
  66                                    DCCP_TIMEWAIT_LEN);
  67                 inet_twsk_put(tw);
  68         } else {
  69                 /* Sorry, if we're out of memory, just CLOSE this
  70                  * socket up.  We've got bigger problems than
  71                  * non-graceful socket closings.
  72                  */
  73                 LIMIT_NETDEBUG(KERN_INFO "DCCP: time wait bucket "
  74                                          "table overflow\n");
  75         }
  76
  77         dccp_done(sk);
  78 }
  79
  80 struct sock *dccp_create_openreq_child(struct sock *sk,
  81                                        const struct request_sock *req,
  82                                        const struct sk_buff *skb)
  83 {
  84         /*
  85          * Step 3: Process LISTEN state
  86          *
  87          * // Generate a new socket and switch to that socket
  88          * Set S := new socket for this port pair
  89          */
  90         struct sock *newsk = inet_csk_clone(sk, req, GFP_ATOMIC);
  91
  92         if (newsk != NULL) {
  93                 const struct dccp_request_sock *dreq = dccp_rsk(req);
  94                 struct inet_connection_sock *newicsk = inet_csk(sk);
  95                 struct dccp_sock *newdp = dccp_sk(newsk);
  96
  97                 newdp->dccps_role          = DCCP_ROLE_SERVER;
  98                 newdp->dccps_hc_rx_ackvec  = NULL;
  99                 newdp->dccps_service_list  = NULL;
 100                 newdp->dccps_service       = dreq->dreq_service;
 101                 newicsk->icsk_rto          = DCCP_TIMEOUT_INIT;
 102                 do_gettimeofday(&newdp->dccps_epoch);
 103
 104                 if (newdp->dccps_options.dccpo_send_ack_vector) {
 105                         newdp->dccps_hc_rx_ackvec =
 106                                 dccp_ackvec_alloc(DCCP_MAX_ACKVEC_LEN,
 107                                                   GFP_ATOMIC);
 108                         /*
 109                          * XXX: We're using the same CCIDs set on the parent,
 110                          * i.e. sk_clone copied the master sock and left the
 111                          * CCID pointers for this child, that is why we do the
 112                          * __ccid_get calls.
 113                          */
 114                         if (unlikely(newdp->dccps_hc_rx_ackvec == NULL))
 115                                 goto out_free;
 116                 }
 117
 118                 if (unlikely(ccid_hc_rx_init(newdp->dccps_hc_rx_ccid,
 119                                              newsk) != 0 ||
 120                              ccid_hc_tx_init(newdp->dccps_hc_tx_ccid,
 121                                              newsk) != 0)) {
 122                         dccp_ackvec_free(newdp->dccps_hc_rx_ackvec);
 123                         ccid_hc_rx_exit(newdp->dccps_hc_rx_ccid, newsk);
 124                         ccid_hc_tx_exit(newdp->dccps_hc_tx_ccid, newsk);
 125 out_free:
 126                         /* It is still raw copy of parent, so invalidate
 127                          * destructor and make plain sk_free() */
 128                         newsk->sk_destruct = NULL;
 129                         sk_free(newsk);
 130                         return NULL;
 131                 }
 132
 133                 __ccid_get(newdp->dccps_hc_rx_ccid);
 134                 __ccid_get(newdp->dccps_hc_tx_ccid);
 135
 136                 /*
 137                  * Step 3: Process LISTEN state
 138                  *
 139                  *      Choose S.ISS (initial seqno) or set from Init Cookie
 140                  *      Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
 141                  *      Cookie
 142                  */
 143
 144                 /* See dccp_v4_conn_request */
 145                 newdp->dccps_options.dccpo_sequence_window = req->rcv_wnd;
 146
 147                 newdp->dccps_gar = newdp->dccps_isr = dreq->dreq_isr;
 148                 dccp_update_gsr(newsk, dreq->dreq_isr);
 149
 150                 newdp->dccps_iss = dreq->dreq_iss;
 151                 dccp_update_gss(newsk, dreq->dreq_iss);
 152
 153                 /*
 154                  * SWL and AWL are initially adjusted so that they are not less than
 155                  * the initial Sequence Numbers received and sent, respectively:
 156                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
 157                  *      AWL := max(GSS - W' + 1, ISS).
 158                  * These adjustments MUST be applied only at the beginning of the
 159                  * connection.
 160                  */
 161                 dccp_set_seqno(&newdp->dccps_swl,
 162                                max48(newdp->dccps_swl, newdp->dccps_isr));
 163                 dccp_set_seqno(&newdp->dccps_awl,
 164                                max48(newdp->dccps_awl, newdp->dccps_iss));
 165
 166                 dccp_init_xmit_timers(newsk);
 167
 168                 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
 169         }
 170         return newsk;
 171 }
 172
 173 /*
 174  * Process an incoming packet for RESPOND sockets represented
 175  * as an request_sock.
 176  */
 177 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 178                             struct request_sock *req,
 179                             struct request_sock **prev)
 180 {
 181         struct sock *child = NULL;
 182
 183         /* Check for retransmitted REQUEST */
 184         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 185                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq,
 186                             dccp_rsk(req)->dreq_isr)) {
 187                         struct dccp_request_sock *dreq = dccp_rsk(req);
 188
 189                         dccp_pr_debug("Retransmitted REQUEST\n");
 190                         /* Send another RESPONSE packet */
 191                         dccp_set_seqno(&dreq->dreq_iss, dreq->dreq_iss + 1);
 192                         dccp_set_seqno(&dreq->dreq_isr,
 193                                        DCCP_SKB_CB(skb)->dccpd_seq);
 194                         req->rsk_ops->rtx_syn_ack(sk, req, NULL);
 195                 }
 196                 /* Network Duplicate, discard packet */
 197                 return NULL;
 198         }
 199
 200         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 201
 202         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 203             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 204                 goto drop;
 205
 206         /* Invalid ACK */
 207         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dccp_rsk(req)->dreq_iss) {
 208                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 209                               "dreq_iss=%llu\n",
 210                               (unsigned long long)
 211                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 212                               (unsigned long long)
 213                               dccp_rsk(req)->dreq_iss);
 214                 goto drop;
 215         }
 216
 217         child = dccp_v4_request_recv_sock(sk, skb, req, NULL);
 218         if (child == NULL)
 219                 goto listen_overflow;
 220
 221         /* FIXME: deal with options */
 222
 223         inet_csk_reqsk_queue_unlink(sk, req, prev);
 224         inet_csk_reqsk_queue_removed(sk, req);
 225         inet_csk_reqsk_queue_add(sk, req, child);
 226 out:
 227         return child;
 228 listen_overflow:
 229         dccp_pr_debug("listen_overflow!\n");
 230         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 231 drop:
 232         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 233                 req->rsk_ops->send_reset(skb);
 234
 235         inet_csk_reqsk_queue_drop(sk, req, prev);
 236         goto out;
 237 }
 238
 239 /*
 240  *  Queue segment on the new socket if the new socket is active,
 241  *  otherwise we just shortcircuit this and continue with
 242  *  the new socket.
 243  */
 244 int dccp_child_process(struct sock *parent, struct sock *child,
 245                        struct sk_buff *skb)
 246 {
 247         int ret = 0;
 248         const int state = child->sk_state;
 249
 250         if (!sock_owned_by_user(child)) {
 251                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 252                                              skb->len);
 253
 254                 /* Wakeup parent, send SIGIO */
 255                 if (state == DCCP_RESPOND && child->sk_state != state)
 256                         parent->sk_data_ready(parent, 0);
 257         } else {
 258                 /* Alas, it is possible again, because we do lookup
 259                  * in main socket hash table and lock on listening
 260                  * socket does not protect us more.
 261                  */
 262                 sk_add_backlog(child, skb);
 263         }
 264
 265         bh_unlock_sock(child);
 266         sock_put(child);
 267         return ret;
 268 }