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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/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                 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
 109                 newdp->dccps_role           = DCCP_ROLE_SERVER;
 110                 newdp->dccps_hc_rx_ackvec   = NULL;
 111                 newdp->dccps_service_list   = NULL;
 112                 newdp->dccps_service        = dreq->dreq_service;
 113                 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
 114                 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
 115                 newicsk->icsk_rto           = DCCP_TIMEOUT_INIT;
 116
 117                 INIT_LIST_HEAD(&newdp->dccps_featneg);
 118                 /*
 119                  * Step 3: Process LISTEN state
 120                  *
 121                  *    Choose S.ISS (initial seqno) or set from Init Cookies
 122                  *    Initialize S.GAR := S.ISS
 123                  *    Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 124                  */
 125                 newdp->dccps_gar = newdp->dccps_iss = dreq->dreq_iss;
 126                 dccp_update_gss(newsk, dreq->dreq_iss);
 127
 128                 newdp->dccps_isr = dreq->dreq_isr;
 129                 dccp_update_gsr(newsk, dreq->dreq_isr);
 130
 131                 /*
 132                  * SWL and AWL are initially adjusted so that they are not less than
 133                  * the initial Sequence Numbers received and sent, respectively:
 134                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
 135                  *      AWL := max(GSS - W' + 1, ISS).
 136                  * These adjustments MUST be applied only at the beginning of the
 137                  * connection.
 138                  */
 139                 dccp_set_seqno(&newdp->dccps_swl,
 140                                max48(newdp->dccps_swl, newdp->dccps_isr));
 141                 dccp_set_seqno(&newdp->dccps_awl,
 142                                max48(newdp->dccps_awl, newdp->dccps_iss));
 143
 144                 /*
 145                  * Activate features after initialising the sequence numbers,
 146                  * since CCID initialisation may depend on GSS, ISR, ISS etc.
 147                  */
 148                 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
 149                         /* It is still raw copy of parent, so invalidate
 150                          * destructor and make plain sk_free() */
 151                         newsk->sk_destruct = NULL;
 152                         sk_free(newsk);
 153                         return NULL;
 154                 }
 155                 dccp_init_xmit_timers(newsk);
 156
 157                 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
 158         }
 159         return newsk;
 160 }
 161
 162 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 163
 164 /*
 165  * Process an incoming packet for RESPOND sockets represented
 166  * as an request_sock.
 167  */
 168 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 169                             struct request_sock *req,
 170                             struct request_sock **prev)
 171 {
 172         struct sock *child = NULL;
 173         struct dccp_request_sock *dreq = dccp_rsk(req);
 174
 175         /* Check for retransmitted REQUEST */
 176         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 177
 178                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_isr)) {
 179                         dccp_pr_debug("Retransmitted REQUEST\n");
 180                         dreq->dreq_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 181                         /*
 182                          * Send another RESPONSE packet
 183                          * To protect against Request floods, increment retrans
 184                          * counter (backoff, monitored by dccp_response_timer).
 185                          */
 186                         req->retrans++;
 187                         req->rsk_ops->rtx_syn_ack(sk, req, NULL);
 188                 }
 189                 /* Network Duplicate, discard packet */
 190                 return NULL;
 191         }
 192
 193         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 194
 195         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 196             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 197                 goto drop;
 198
 199         /* Invalid ACK */
 200         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dreq->dreq_iss) {
 201                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 202                               "dreq_iss=%llu\n",
 203                               (unsigned long long)
 204                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 205                               (unsigned long long) dreq->dreq_iss);
 206                 goto drop;
 207         }
 208
 209         if (dccp_parse_options(sk, dreq, skb))
 210                  goto drop;
 211
 212         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 213         if (child == NULL)
 214                 goto listen_overflow;
 215
 216         inet_csk_reqsk_queue_unlink(sk, req, prev);
 217         inet_csk_reqsk_queue_removed(sk, req);
 218         inet_csk_reqsk_queue_add(sk, req, child);
 219 out:
 220         return child;
 221 listen_overflow:
 222         dccp_pr_debug("listen_overflow!\n");
 223         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 224 drop:
 225         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 226                 req->rsk_ops->send_reset(sk, skb);
 227
 228         inet_csk_reqsk_queue_drop(sk, req, prev);
 229         goto out;
 230 }
 231
 232 EXPORT_SYMBOL_GPL(dccp_check_req);
 233
 234 /*
 235  *  Queue segment on the new socket if the new socket is active,
 236  *  otherwise we just shortcircuit this and continue with
 237  *  the new socket.
 238  */
 239 int dccp_child_process(struct sock *parent, struct sock *child,
 240                        struct sk_buff *skb)
 241 {
 242         int ret = 0;
 243         const int state = child->sk_state;
 244
 245         if (!sock_owned_by_user(child)) {
 246                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 247                                              skb->len);
 248
 249                 /* Wakeup parent, send SIGIO */
 250                 if (state == DCCP_RESPOND && child->sk_state != state)
 251                         parent->sk_data_ready(parent, 0);
 252         } else {
 253                 /* Alas, it is possible again, because we do lookup
 254                  * in main socket hash table and lock on listening
 255                  * socket does not protect us more.
 256                  */
 257                 sk_add_backlog(child, skb);
 258         }
 259
 260         bh_unlock_sock(child);
 261         sock_put(child);
 262         return ret;
 263 }
 264
 265 EXPORT_SYMBOL_GPL(dccp_child_process);
 266
 267 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 268                          struct request_sock *rsk)
 269 {
 270         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 271 }
 272
 273 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 274
 275 int dccp_reqsk_init(struct request_sock *req,
 276                     struct dccp_sock const *dp, struct sk_buff const *skb)
 277 {
 278         struct dccp_request_sock *dreq = dccp_rsk(req);
 279
 280         inet_rsk(req)->rmt_port   = dccp_hdr(skb)->dccph_sport;
 281         inet_rsk(req)->loc_port   = dccp_hdr(skb)->dccph_dport;
 282         inet_rsk(req)->acked      = 0;
 283         dreq->dreq_timestamp_echo = 0;
 284
 285         /* inherit feature negotiation options from listening socket */
 286         return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 287 }
 288
 289 EXPORT_SYMBOL_GPL(dccp_reqsk_init);