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                 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 from packet (or Init Cookies)
 124                  *
 125                  *    Setting AWL/AWH and SWL/SWH happens as part of the feature
 126                  *    activation below, as these windows all depend on the local
 127                  *    and remote Sequence Window feature values (7.5.2).
 128                  */
 129                 newdp->dccps_gss = newdp->dccps_iss = dreq->dreq_iss;
 130                 newdp->dccps_gar = newdp->dccps_iss;
 131                 newdp->dccps_gsr = newdp->dccps_isr = dreq->dreq_isr;
 132
 133                 /*
 134                  * Activate features: initialise CCIDs, sequence windows etc.
 135                  */
 136                 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
 137                         /* It is still raw copy of parent, so invalidate
 138                          * destructor and make plain sk_free() */
 139                         newsk->sk_destruct = NULL;
 140                         sk_free(newsk);
 141                         return NULL;
 142                 }
 143                 dccp_init_xmit_timers(newsk);
 144
 145                 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
 146         }
 147         return newsk;
 148 }
 149
 150 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 151
 152 /*
 153  * Process an incoming packet for RESPOND sockets represented
 154  * as an request_sock.
 155  */
 156 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 157                             struct request_sock *req,
 158                             struct request_sock **prev)
 159 {
 160         struct sock *child = NULL;
 161         struct dccp_request_sock *dreq = dccp_rsk(req);
 162
 163         /* Check for retransmitted REQUEST */
 164         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 165
 166                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_isr)) {
 167                         dccp_pr_debug("Retransmitted REQUEST\n");
 168                         dreq->dreq_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 169                         /*
 170                          * Send another RESPONSE packet
 171                          * To protect against Request floods, increment retrans
 172                          * counter (backoff, monitored by dccp_response_timer).
 173                          */
 174                         req->retrans++;
 175                         req->rsk_ops->rtx_syn_ack(sk, req);
 176                 }
 177                 /* Network Duplicate, discard packet */
 178                 return NULL;
 179         }
 180
 181         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 182
 183         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 184             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 185                 goto drop;
 186
 187         /* Invalid ACK */
 188         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dreq->dreq_iss) {
 189                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 190                               "dreq_iss=%llu\n",
 191                               (unsigned long long)
 192                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 193                               (unsigned long long) dreq->dreq_iss);
 194                 goto drop;
 195         }
 196
 197         if (dccp_parse_options(sk, dreq, skb))
 198                  goto drop;
 199
 200         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 201         if (child == NULL)
 202                 goto listen_overflow;
 203
 204         inet_csk_reqsk_queue_unlink(sk, req, prev);
 205         inet_csk_reqsk_queue_removed(sk, req);
 206         inet_csk_reqsk_queue_add(sk, req, child);
 207 out:
 208         return child;
 209 listen_overflow:
 210         dccp_pr_debug("listen_overflow!\n");
 211         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 212 drop:
 213         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 214                 req->rsk_ops->send_reset(sk, skb);
 215
 216         inet_csk_reqsk_queue_drop(sk, req, prev);
 217         goto out;
 218 }
 219
 220 EXPORT_SYMBOL_GPL(dccp_check_req);
 221
 222 /*
 223  *  Queue segment on the new socket if the new socket is active,
 224  *  otherwise we just shortcircuit this and continue with
 225  *  the new socket.
 226  */
 227 int dccp_child_process(struct sock *parent, struct sock *child,
 228                        struct sk_buff *skb)
 229 {
 230         int ret = 0;
 231         const int state = child->sk_state;
 232
 233         if (!sock_owned_by_user(child)) {
 234                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 235                                              skb->len);
 236
 237                 /* Wakeup parent, send SIGIO */
 238                 if (state == DCCP_RESPOND && child->sk_state != state)
 239                         parent->sk_data_ready(parent, 0);
 240         } else {
 241                 /* Alas, it is possible again, because we do lookup
 242                  * in main socket hash table and lock on listening
 243                  * socket does not protect us more.
 244                  */
 245                 sk_add_backlog(child, skb);
 246         }
 247
 248         bh_unlock_sock(child);
 249         sock_put(child);
 250         return ret;
 251 }
 252
 253 EXPORT_SYMBOL_GPL(dccp_child_process);
 254
 255 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 256                          struct request_sock *rsk)
 257 {
 258         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 259 }
 260
 261 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 262
 263 int dccp_reqsk_init(struct request_sock *req,
 264                     struct dccp_sock const *dp, struct sk_buff const *skb)
 265 {
 266         struct dccp_request_sock *dreq = dccp_rsk(req);
 267
 268         inet_rsk(req)->rmt_port   = dccp_hdr(skb)->dccph_sport;
 269         inet_rsk(req)->acked      = 0;
 270         dreq->dreq_timestamp_echo = 0;
 271
 272         /* inherit feature negotiation options from listening socket */
 273         return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 274 }
 275
 276 EXPORT_SYMBOL_GPL(dccp_reqsk_init);