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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 /* Short-time timewait calendar */
  36
  37         .twcal_hand     = -1,
  38         .twcal_timer    = TIMER_INITIALIZER(inet_twdr_twcal_tick, 0,
  39                                             (unsigned long)&dccp_death_row),
  40 };
  41
  42 EXPORT_SYMBOL_GPL(dccp_death_row);
  43
  44 void dccp_time_wait(struct sock *sk, int state, int timeo)
  45 {
  46         struct inet_timewait_sock *tw = NULL;
  47
  48         if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
  49                 tw = inet_twsk_alloc(sk, state);
  50
  51         if (tw != NULL) {
  52                 const struct inet_connection_sock *icsk = inet_csk(sk);
  53                 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  54 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
  55                 if (tw->tw_family == PF_INET6) {
  56                         const struct ipv6_pinfo *np = inet6_sk(sk);
  57                         struct inet6_timewait_sock *tw6;
  58
  59                         tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot);
  60                         tw6 = inet6_twsk((struct sock *)tw);
  61                         ipv6_addr_copy(&tw6->tw_v6_daddr, &np->daddr);
  62                         ipv6_addr_copy(&tw6->tw_v6_rcv_saddr, &np->rcv_saddr);
  63                         tw->tw_ipv6only = np->ipv6only;
  64                 }
  65 #endif
  66                 /* Linkage updates. */
  67                 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  68
  69                 /* Get the TIME_WAIT timeout firing. */
  70                 if (timeo < rto)
  71                         timeo = rto;
  72
  73                 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
  74                 if (state == DCCP_TIME_WAIT)
  75                         timeo = DCCP_TIMEWAIT_LEN;
  76
  77                 inet_twsk_schedule(tw, &dccp_death_row, timeo,
  78                                    DCCP_TIMEWAIT_LEN);
  79                 inet_twsk_put(tw);
  80         } else {
  81                 /* Sorry, if we're out of memory, just CLOSE this
  82                  * socket up.  We've got bigger problems than
  83                  * non-graceful socket closings.
  84                  */
  85                 LIMIT_NETDEBUG(KERN_INFO "DCCP: time wait bucket "
  86                                          "table overflow\n");
  87         }
  88
  89         dccp_done(sk);
  90 }
  91
  92 struct sock *dccp_create_openreq_child(struct sock *sk,
  93                                        const struct request_sock *req,
  94                                        const struct sk_buff *skb)
  95 {
  96         /*
  97          * Step 3: Process LISTEN state
  98          *
  99          * // Generate a new socket and switch to that socket
 100          * Set S := new socket for this port pair
 101          */
 102         struct sock *newsk = inet_csk_clone(sk, req, GFP_ATOMIC);
 103
 104         if (newsk != NULL) {
 105                 const struct dccp_request_sock *dreq = dccp_rsk(req);
 106                 struct inet_connection_sock *newicsk = inet_csk(sk);
 107                 struct dccp_sock *newdp = dccp_sk(newsk);
 108                 struct dccp_minisock *newdmsk = dccp_msk(newsk);
 109
 110                 newdp->dccps_role          = DCCP_ROLE_SERVER;
 111                 newdp->dccps_hc_rx_ackvec  = NULL;
 112                 newdp->dccps_service_list  = NULL;
 113                 newdp->dccps_service       = dreq->dreq_service;
 114                 newicsk->icsk_rto          = DCCP_TIMEOUT_INIT;
 115                 do_gettimeofday(&newdp->dccps_epoch);
 116
 117                 if (dccp_feat_clone(sk, newsk))
 118                         goto out_free;
 119
 120                 if (newdmsk->dccpms_send_ack_vector) {
 121                         newdp->dccps_hc_rx_ackvec =
 122                                                 dccp_ackvec_alloc(GFP_ATOMIC);
 123                         if (unlikely(newdp->dccps_hc_rx_ackvec == NULL))
 124                                 goto out_free;
 125                 }
 126
 127                 newdp->dccps_hc_rx_ccid =
 128                             ccid_hc_rx_new(newdmsk->dccpms_rx_ccid,
 129                                            newsk, GFP_ATOMIC);
 130                 newdp->dccps_hc_tx_ccid =
 131                             ccid_hc_tx_new(newdmsk->dccpms_tx_ccid,
 132                                            newsk, GFP_ATOMIC);
 133                 if (unlikely(newdp->dccps_hc_rx_ccid == NULL ||
 134                              newdp->dccps_hc_tx_ccid == NULL)) {
 135                         dccp_ackvec_free(newdp->dccps_hc_rx_ackvec);
 136                         ccid_hc_rx_delete(newdp->dccps_hc_rx_ccid, newsk);
 137                         ccid_hc_tx_delete(newdp->dccps_hc_tx_ccid, newsk);
 138 out_free:
 139                         /* It is still raw copy of parent, so invalidate
 140                          * destructor and make plain sk_free() */
 141                         newsk->sk_destruct = NULL;
 142                         sk_free(newsk);
 143                         return NULL;
 144                 }
 145
 146                 /*
 147                  * Step 3: Process LISTEN state
 148                  *
 149                  *      Choose S.ISS (initial seqno) or set from Init Cookie
 150                  *      Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
 151                  *      Cookie
 152                  */
 153
 154                 /* See dccp_v4_conn_request */
 155                 newdmsk->dccpms_sequence_window = req->rcv_wnd;
 156
 157                 newdp->dccps_gar = newdp->dccps_isr = dreq->dreq_isr;
 158                 dccp_update_gsr(newsk, dreq->dreq_isr);
 159
 160                 newdp->dccps_iss = dreq->dreq_iss;
 161                 dccp_update_gss(newsk, dreq->dreq_iss);
 162
 163                 /*
 164                  * SWL and AWL are initially adjusted so that they are not less than
 165                  * the initial Sequence Numbers received and sent, respectively:
 166                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
 167                  *      AWL := max(GSS - W' + 1, ISS).
 168                  * These adjustments MUST be applied only at the beginning of the
 169                  * connection.
 170                  */
 171                 dccp_set_seqno(&newdp->dccps_swl,
 172                                max48(newdp->dccps_swl, newdp->dccps_isr));
 173                 dccp_set_seqno(&newdp->dccps_awl,
 174                                max48(newdp->dccps_awl, newdp->dccps_iss));
 175
 176                 dccp_init_xmit_timers(newsk);
 177
 178                 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
 179         }
 180         return newsk;
 181 }
 182
 183 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 184
 185 /*
 186  * Process an incoming packet for RESPOND sockets represented
 187  * as an request_sock.
 188  */
 189 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 190                             struct request_sock *req,
 191                             struct request_sock **prev)
 192 {
 193         struct sock *child = NULL;
 194
 195         /* Check for retransmitted REQUEST */
 196         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 197                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq,
 198                             dccp_rsk(req)->dreq_isr)) {
 199                         struct dccp_request_sock *dreq = dccp_rsk(req);
 200
 201                         dccp_pr_debug("Retransmitted REQUEST\n");
 202                         /* Send another RESPONSE packet */
 203                         dccp_set_seqno(&dreq->dreq_iss, dreq->dreq_iss + 1);
 204                         dccp_set_seqno(&dreq->dreq_isr,
 205                                        DCCP_SKB_CB(skb)->dccpd_seq);
 206                         req->rsk_ops->rtx_syn_ack(sk, req, NULL);
 207                 }
 208                 /* Network Duplicate, discard packet */
 209                 return NULL;
 210         }
 211
 212         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 213
 214         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 215             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 216                 goto drop;
 217
 218         /* Invalid ACK */
 219         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dccp_rsk(req)->dreq_iss) {
 220                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 221                               "dreq_iss=%llu\n",
 222                               (unsigned long long)
 223                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 224                               (unsigned long long)
 225                               dccp_rsk(req)->dreq_iss);
 226                 goto drop;
 227         }
 228
 229         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 230         if (child == NULL)
 231                 goto listen_overflow;
 232
 233         /* FIXME: deal with options */
 234
 235         inet_csk_reqsk_queue_unlink(sk, req, prev);
 236         inet_csk_reqsk_queue_removed(sk, req);
 237         inet_csk_reqsk_queue_add(sk, req, child);
 238 out:
 239         return child;
 240 listen_overflow:
 241         dccp_pr_debug("listen_overflow!\n");
 242         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 243 drop:
 244         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 245                 req->rsk_ops->send_reset(skb);
 246
 247         inet_csk_reqsk_queue_drop(sk, req, prev);
 248         goto out;
 249 }
 250
 251 EXPORT_SYMBOL_GPL(dccp_check_req);
 252
 253 /*
 254  *  Queue segment on the new socket if the new socket is active,
 255  *  otherwise we just shortcircuit this and continue with
 256  *  the new socket.
 257  */
 258 int dccp_child_process(struct sock *parent, struct sock *child,
 259                        struct sk_buff *skb)
 260 {
 261         int ret = 0;
 262         const int state = child->sk_state;
 263
 264         if (!sock_owned_by_user(child)) {
 265                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 266                                              skb->len);
 267
 268                 /* Wakeup parent, send SIGIO */
 269                 if (state == DCCP_RESPOND && child->sk_state != state)
 270                         parent->sk_data_ready(parent, 0);
 271         } else {
 272                 /* Alas, it is possible again, because we do lookup
 273                  * in main socket hash table and lock on listening
 274                  * socket does not protect us more.
 275                  */
 276                 sk_add_backlog(child, skb);
 277         }
 278
 279         bh_unlock_sock(child);
 280         sock_put(child);
 281         return ret;
 282 }
 283
 284 EXPORT_SYMBOL_GPL(dccp_child_process);