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   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/dccp.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/timer.h>
  16
  17 #include <net/sock.h>
  18 #include <net/xfrm.h>
  19 #include <net/inet_timewait_sock.h>
  20
  21 #include "ackvec.h"
  22 #include "ccid.h"
  23 #include "dccp.h"
  24 #include "feat.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 EXPORT_SYMBOL_GPL(dccp_death_row);
  44
  45 void dccp_time_wait(struct sock *sk, int state, int timeo)
  46 {
  47         struct inet_timewait_sock *tw = NULL;
  48
  49         if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
  50                 tw = inet_twsk_alloc(sk, state);
  51
  52         if (tw != NULL) {
  53                 const struct inet_connection_sock *icsk = inet_csk(sk);
  54                 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  55 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
  56                 if (tw->tw_family == PF_INET6) {
  57                         const struct ipv6_pinfo *np = inet6_sk(sk);
  58                         struct inet6_timewait_sock *tw6;
  59
  60                         tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot);
  61                         tw6 = inet6_twsk((struct sock *)tw);
  62                         ipv6_addr_copy(&tw6->tw_v6_daddr, &np->daddr);
  63                         ipv6_addr_copy(&tw6->tw_v6_rcv_saddr, &np->rcv_saddr);
  64                         tw->tw_ipv6only = np->ipv6only;
  65                 }
  66 #endif
  67                 /* Linkage updates. */
  68                 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  69
  70                 /* Get the TIME_WAIT timeout firing. */
  71                 if (timeo < rto)
  72                         timeo = rto;
  73
  74                 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
  75                 if (state == DCCP_TIME_WAIT)
  76                         timeo = DCCP_TIMEWAIT_LEN;
  77
  78                 inet_twsk_schedule(tw, &dccp_death_row, timeo,
  79                                    DCCP_TIMEWAIT_LEN);
  80                 inet_twsk_put(tw);
  81         } else {
  82                 /* Sorry, if we're out of memory, just CLOSE this
  83                  * socket up.  We've got bigger problems than
  84                  * non-graceful socket closings.
  85                  */
  86                 LIMIT_NETDEBUG(KERN_INFO "DCCP: time wait bucket "
  87                                          "table overflow\n");
  88         }
  89
  90         dccp_done(sk);
  91 }
  92
  93 struct sock *dccp_create_openreq_child(struct sock *sk,
  94                                        const struct request_sock *req,
  95                                        const struct sk_buff *skb)
  96 {
  97         /*
  98          * Step 3: Process LISTEN state
  99          *
 100          * // Generate a new socket and switch to that socket
 101          * Set S := new socket for this port pair
 102          */
 103         struct sock *newsk = inet_csk_clone(sk, req, GFP_ATOMIC);
 104
 105         if (newsk != NULL) {
 106                 const struct dccp_request_sock *dreq = dccp_rsk(req);
 107                 struct inet_connection_sock *newicsk = inet_csk(sk);
 108                 struct dccp_sock *newdp = dccp_sk(newsk);
 109                 struct dccp_minisock *newdmsk = dccp_msk(newsk);
 110
 111                 newdp->dccps_role          = DCCP_ROLE_SERVER;
 112                 newdp->dccps_hc_rx_ackvec  = NULL;
 113                 newdp->dccps_service_list  = NULL;
 114                 newdp->dccps_service       = dreq->dreq_service;
 115                 newicsk->icsk_rto          = DCCP_TIMEOUT_INIT;
 116                 do_gettimeofday(&newdp->dccps_epoch);
 117
 118                 if (dccp_feat_clone(sk, newsk))
 119                         goto out_free;
 120
 121                 if (newdmsk->dccpms_send_ack_vector) {
 122                         newdp->dccps_hc_rx_ackvec =
 123                                                 dccp_ackvec_alloc(GFP_ATOMIC);
 124                         if (unlikely(newdp->dccps_hc_rx_ackvec == NULL))
 125                                 goto out_free;
 126                 }
 127
 128                 newdp->dccps_hc_rx_ccid =
 129                             ccid_hc_rx_new(newdmsk->dccpms_rx_ccid,
 130                                            newsk, GFP_ATOMIC);
 131                 newdp->dccps_hc_tx_ccid =
 132                             ccid_hc_tx_new(newdmsk->dccpms_tx_ccid,
 133                                            newsk, GFP_ATOMIC);
 134                 if (unlikely(newdp->dccps_hc_rx_ccid == NULL ||
 135                              newdp->dccps_hc_tx_ccid == NULL)) {
 136                         dccp_ackvec_free(newdp->dccps_hc_rx_ackvec);
 137                         ccid_hc_rx_delete(newdp->dccps_hc_rx_ccid, newsk);
 138                         ccid_hc_tx_delete(newdp->dccps_hc_tx_ccid, newsk);
 139 out_free:
 140                         /* It is still raw copy of parent, so invalidate
 141                          * destructor and make plain sk_free() */
 142                         newsk->sk_destruct = NULL;
 143                         sk_free(newsk);
 144                         return NULL;
 145                 }
 146
 147                 /*
 148                  * Step 3: Process LISTEN state
 149                  *
 150                  *      Choose S.ISS (initial seqno) or set from Init Cookie
 151                  *      Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
 152                  *      Cookie
 153                  */
 154
 155                 /* See dccp_v4_conn_request */
 156                 newdmsk->dccpms_sequence_window = req->rcv_wnd;
 157
 158                 newdp->dccps_gar = newdp->dccps_isr = dreq->dreq_isr;
 159                 dccp_update_gsr(newsk, dreq->dreq_isr);
 160
 161                 newdp->dccps_iss = dreq->dreq_iss;
 162                 dccp_update_gss(newsk, dreq->dreq_iss);
 163
 164                 /*
 165                  * SWL and AWL are initially adjusted so that they are not less than
 166                  * the initial Sequence Numbers received and sent, respectively:
 167                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
 168                  *      AWL := max(GSS - W' + 1, ISS).
 169                  * These adjustments MUST be applied only at the beginning of the
 170                  * connection.
 171                  */
 172                 dccp_set_seqno(&newdp->dccps_swl,
 173                                max48(newdp->dccps_swl, newdp->dccps_isr));
 174                 dccp_set_seqno(&newdp->dccps_awl,
 175                                max48(newdp->dccps_awl, newdp->dccps_iss));
 176
 177                 dccp_init_xmit_timers(newsk);
 178
 179                 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
 180         }
 181         return newsk;
 182 }
 183
 184 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 185
 186 /*
 187  * Process an incoming packet for RESPOND sockets represented
 188  * as an request_sock.
 189  */
 190 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 191                             struct request_sock *req,
 192                             struct request_sock **prev)
 193 {
 194         struct sock *child = NULL;
 195
 196         /* Check for retransmitted REQUEST */
 197         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 198                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq,
 199                             dccp_rsk(req)->dreq_isr)) {
 200                         struct dccp_request_sock *dreq = dccp_rsk(req);
 201
 202                         dccp_pr_debug("Retransmitted REQUEST\n");
 203                         /* Send another RESPONSE packet */
 204                         dccp_set_seqno(&dreq->dreq_iss, dreq->dreq_iss + 1);
 205                         dccp_set_seqno(&dreq->dreq_isr,
 206                                        DCCP_SKB_CB(skb)->dccpd_seq);
 207                         req->rsk_ops->rtx_syn_ack(sk, req, NULL);
 208                 }
 209                 /* Network Duplicate, discard packet */
 210                 return NULL;
 211         }
 212
 213         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 214
 215         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 216             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 217                 goto drop;
 218
 219         /* Invalid ACK */
 220         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dccp_rsk(req)->dreq_iss) {
 221                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 222                               "dreq_iss=%llu\n",
 223                               (unsigned long long)
 224                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 225                               (unsigned long long)
 226                               dccp_rsk(req)->dreq_iss);
 227                 goto drop;
 228         }
 229
 230         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 231         if (child == NULL)
 232                 goto listen_overflow;
 233
 234         /* FIXME: deal with options */
 235
 236         inet_csk_reqsk_queue_unlink(sk, req, prev);
 237         inet_csk_reqsk_queue_removed(sk, req);
 238         inet_csk_reqsk_queue_add(sk, req, child);
 239 out:
 240         return child;
 241 listen_overflow:
 242         dccp_pr_debug("listen_overflow!\n");
 243         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 244 drop:
 245         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 246                 req->rsk_ops->send_reset(skb);
 247
 248         inet_csk_reqsk_queue_drop(sk, req, prev);
 249         goto out;
 250 }
 251
 252 EXPORT_SYMBOL_GPL(dccp_check_req);
 253
 254 /*
 255  *  Queue segment on the new socket if the new socket is active,
 256  *  otherwise we just shortcircuit this and continue with
 257  *  the new socket.
 258  */
 259 int dccp_child_process(struct sock *parent, struct sock *child,
 260                        struct sk_buff *skb)
 261 {
 262         int ret = 0;
 263         const int state = child->sk_state;
 264
 265         if (!sock_owned_by_user(child)) {
 266                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 267                                              skb->len);
 268
 269                 /* Wakeup parent, send SIGIO */
 270                 if (state == DCCP_RESPOND && child->sk_state != state)
 271                         parent->sk_data_ready(parent, 0);
 272         } else {
 273                 /* Alas, it is possible again, because we do lookup
 274                  * in main socket hash table and lock on listening
 275                  * socket does not protect us more.
 276                  */
 277                 sk_add_backlog(child, skb);
 278         }
 279
 280         bh_unlock_sock(child);
 281         sock_put(child);
 282         return ret;
 283 }
 284
 285 EXPORT_SYMBOL_GPL(dccp_child_process);