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/dccp.h>
  14 #include <linux/kernel.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 #include "feat.h"
  26
  27 struct inet_timewait_death_row dccp_death_row = {
  28         .sysctl_max_tw_buckets = NR_FILE * 2,
  29         .period         = DCCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS,
  30         .death_lock     = __SPIN_LOCK_UNLOCKED(dccp_death_row.death_lock),
  31         .hashinfo       = &dccp_hashinfo,
  32         .tw_timer       = TIMER_INITIALIZER(inet_twdr_hangman, 0,
  33                                             (unsigned long)&dccp_death_row),
  34         .twkill_work    = __WORK_INITIALIZER(dccp_death_row.twkill_work,
  35                                              inet_twdr_twkill_work),
  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                 DCCP_WARN("time wait bucket 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(newsk);
 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 Cookies
 150                  *    Initialize S.GAR := S.ISS
 151                  *    Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 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                 struct dccp_request_sock *dreq = dccp_rsk(req);
 198
 199                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_isr)) {
 200                         dccp_pr_debug("Retransmitted REQUEST\n");
 201                         dreq->dreq_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 202                         /*
 203                          * Send another RESPONSE packet
 204                          * To protect against Request floods, increment retrans
 205                          * counter (backoff, monitored by dccp_response_timer).
 206                          */
 207                         req->retrans++;
 208                         req->rsk_ops->rtx_syn_ack(sk, req, NULL);
 209                 }
 210                 /* Network Duplicate, discard packet */
 211                 return NULL;
 212         }
 213
 214         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 215
 216         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 217             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 218                 goto drop;
 219
 220         /* Invalid ACK */
 221         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dccp_rsk(req)->dreq_iss) {
 222                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 223                               "dreq_iss=%llu\n",
 224                               (unsigned long long)
 225                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 226                               (unsigned long long)
 227                               dccp_rsk(req)->dreq_iss);
 228                 goto drop;
 229         }
 230
 231         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 232         if (child == NULL)
 233                 goto listen_overflow;
 234
 235         /* FIXME: deal with options */
 236
 237         inet_csk_reqsk_queue_unlink(sk, req, prev);
 238         inet_csk_reqsk_queue_removed(sk, req);
 239         inet_csk_reqsk_queue_add(sk, req, child);
 240 out:
 241         return child;
 242 listen_overflow:
 243         dccp_pr_debug("listen_overflow!\n");
 244         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 245 drop:
 246         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 247                 req->rsk_ops->send_reset(sk, skb);
 248
 249         inet_csk_reqsk_queue_drop(sk, req, prev);
 250         goto out;
 251 }
 252
 253 EXPORT_SYMBOL_GPL(dccp_check_req);
 254
 255 /*
 256  *  Queue segment on the new socket if the new socket is active,
 257  *  otherwise we just shortcircuit this and continue with
 258  *  the new socket.
 259  */
 260 int dccp_child_process(struct sock *parent, struct sock *child,
 261                        struct sk_buff *skb)
 262 {
 263         int ret = 0;
 264         const int state = child->sk_state;
 265
 266         if (!sock_owned_by_user(child)) {
 267                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 268                                              skb->len);
 269
 270                 /* Wakeup parent, send SIGIO */
 271                 if (state == DCCP_RESPOND && child->sk_state != state)
 272                         parent->sk_data_ready(parent, 0);
 273         } else {
 274                 /* Alas, it is possible again, because we do lookup
 275                  * in main socket hash table and lock on listening
 276                  * socket does not protect us more.
 277                  */
 278                 sk_add_backlog(child, skb);
 279         }
 280
 281         bh_unlock_sock(child);
 282         sock_put(child);
 283         return ret;
 284 }
 285
 286 EXPORT_SYMBOL_GPL(dccp_child_process);
 287
 288 void dccp_reqsk_send_ack(struct sk_buff *skb, struct request_sock *rsk)
 289 {
 290         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 291 }
 292
 293 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 294
 295 void dccp_reqsk_init(struct request_sock *req, struct sk_buff *skb)
 296 {
 297         inet_rsk(req)->rmt_port = dccp_hdr(skb)->dccph_sport;
 298         inet_rsk(req)->acked    = 0;
 299         req->rcv_wnd            = sysctl_dccp_feat_sequence_window;
 300 }
 301
 302 EXPORT_SYMBOL_GPL(dccp_reqsk_init);