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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_minisock_init(struct dccp_minisock *dmsk)
  46 {
  47         dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
  48         dmsk->dccpms_send_ack_vector = sysctl_dccp_feat_send_ack_vector;
  49 }
  50
  51 void dccp_time_wait(struct sock *sk, int state, int timeo)
  52 {
  53         struct inet_timewait_sock *tw = NULL;
  54
  55         if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
  56                 tw = inet_twsk_alloc(sk, state);
  57
  58         if (tw != NULL) {
  59                 const struct inet_connection_sock *icsk = inet_csk(sk);
  60                 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  61 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
  62                 if (tw->tw_family == PF_INET6) {
  63                         const struct ipv6_pinfo *np = inet6_sk(sk);
  64                         struct inet6_timewait_sock *tw6;
  65
  66                         tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot);
  67                         tw6 = inet6_twsk((struct sock *)tw);
  68                         ipv6_addr_copy(&tw6->tw_v6_daddr, &np->daddr);
  69                         ipv6_addr_copy(&tw6->tw_v6_rcv_saddr, &np->rcv_saddr);
  70                         tw->tw_ipv6only = np->ipv6only;
  71                 }
  72 #endif
  73                 /* Linkage updates. */
  74                 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  75
  76                 /* Get the TIME_WAIT timeout firing. */
  77                 if (timeo < rto)
  78                         timeo = rto;
  79
  80                 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
  81                 if (state == DCCP_TIME_WAIT)
  82                         timeo = DCCP_TIMEWAIT_LEN;
  83
  84                 inet_twsk_schedule(tw, &dccp_death_row, timeo,
  85                                    DCCP_TIMEWAIT_LEN);
  86                 inet_twsk_put(tw);
  87         } else {
  88                 /* Sorry, if we're out of memory, just CLOSE this
  89                  * socket up.  We've got bigger problems than
  90                  * non-graceful socket closings.
  91                  */
  92                 DCCP_WARN("time wait bucket table overflow\n");
  93         }
  94
  95         dccp_done(sk);
  96 }
  97
  98 struct sock *dccp_create_openreq_child(struct sock *sk,
  99                                        const struct request_sock *req,
 100                                        const struct sk_buff *skb)
 101 {
 102         /*
 103          * Step 3: Process LISTEN state
 104          *
 105          *   (* Generate a new socket and switch to that socket *)
 106          *   Set S := new socket for this port pair
 107          */
 108         struct sock *newsk = inet_csk_clone(sk, req, GFP_ATOMIC);
 109
 110         if (newsk != NULL) {
 111                 struct dccp_request_sock *dreq = dccp_rsk(req);
 112                 struct inet_connection_sock *newicsk = inet_csk(newsk);
 113                 struct dccp_sock *newdp = dccp_sk(newsk);
 114                 struct dccp_minisock *newdmsk = dccp_msk(newsk);
 115
 116                 newdp->dccps_role           = DCCP_ROLE_SERVER;
 117                 newdp->dccps_hc_rx_ackvec   = NULL;
 118                 newdp->dccps_service_list   = NULL;
 119                 newdp->dccps_service        = dreq->dreq_service;
 120                 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
 121                 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
 122                 newicsk->icsk_rto           = DCCP_TIMEOUT_INIT;
 123
 124                 INIT_LIST_HEAD(&newdp->dccps_featneg);
 125                 /*
 126                  * Step 3: Process LISTEN state
 127                  *
 128                  *    Choose S.ISS (initial seqno) or set from Init Cookies
 129                  *    Initialize S.GAR := S.ISS
 130                  *    Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 131                  */
 132
 133                 /* See dccp_v4_conn_request */
 134                 newdmsk->dccpms_sequence_window = req->rcv_wnd;
 135
 136                 newdp->dccps_gar = newdp->dccps_iss = dreq->dreq_iss;
 137                 dccp_update_gss(newsk, dreq->dreq_iss);
 138
 139                 newdp->dccps_isr = dreq->dreq_isr;
 140                 dccp_update_gsr(newsk, dreq->dreq_isr);
 141
 142                 /*
 143                  * SWL and AWL are initially adjusted so that they are not less than
 144                  * the initial Sequence Numbers received and sent, respectively:
 145                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
 146                  *      AWL := max(GSS - W' + 1, ISS).
 147                  * These adjustments MUST be applied only at the beginning of the
 148                  * connection.
 149                  */
 150                 dccp_set_seqno(&newdp->dccps_swl,
 151                                max48(newdp->dccps_swl, newdp->dccps_isr));
 152                 dccp_set_seqno(&newdp->dccps_awl,
 153                                max48(newdp->dccps_awl, newdp->dccps_iss));
 154
 155                 /*
 156                  * Activate features after initialising the sequence numbers,
 157                  * since CCID initialisation may depend on GSS, ISR, ISS etc.
 158                  */
 159                 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
 160                         /* It is still raw copy of parent, so invalidate
 161                          * destructor and make plain sk_free() */
 162                         newsk->sk_destruct = NULL;
 163                         sk_free(newsk);
 164                         return NULL;
 165                 }
 166                 dccp_init_xmit_timers(newsk);
 167
 168                 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
 169         }
 170         return newsk;
 171 }
 172
 173 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 174
 175 /*
 176  * Process an incoming packet for RESPOND sockets represented
 177  * as an request_sock.
 178  */
 179 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 180                             struct request_sock *req,
 181                             struct request_sock **prev)
 182 {
 183         struct sock *child = NULL;
 184         struct dccp_request_sock *dreq = dccp_rsk(req);
 185
 186         /* Check for retransmitted REQUEST */
 187         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 188
 189                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_isr)) {
 190                         dccp_pr_debug("Retransmitted REQUEST\n");
 191                         dreq->dreq_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 192                         /*
 193                          * Send another RESPONSE packet
 194                          * To protect against Request floods, increment retrans
 195                          * counter (backoff, monitored by dccp_response_timer).
 196                          */
 197                         req->retrans++;
 198                         req->rsk_ops->rtx_syn_ack(sk, req);
 199                 }
 200                 /* Network Duplicate, discard packet */
 201                 return NULL;
 202         }
 203
 204         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 205
 206         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 207             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 208                 goto drop;
 209
 210         /* Invalid ACK */
 211         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dreq->dreq_iss) {
 212                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 213                               "dreq_iss=%llu\n",
 214                               (unsigned long long)
 215                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 216                               (unsigned long long) dreq->dreq_iss);
 217                 goto drop;
 218         }
 219
 220         if (dccp_parse_options(sk, dreq, skb))
 221                  goto drop;
 222
 223         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 224         if (child == NULL)
 225                 goto listen_overflow;
 226
 227         inet_csk_reqsk_queue_unlink(sk, req, prev);
 228         inet_csk_reqsk_queue_removed(sk, req);
 229         inet_csk_reqsk_queue_add(sk, req, child);
 230 out:
 231         return child;
 232 listen_overflow:
 233         dccp_pr_debug("listen_overflow!\n");
 234         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 235 drop:
 236         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 237                 req->rsk_ops->send_reset(sk, skb);
 238
 239         inet_csk_reqsk_queue_drop(sk, req, prev);
 240         goto out;
 241 }
 242
 243 EXPORT_SYMBOL_GPL(dccp_check_req);
 244
 245 /*
 246  *  Queue segment on the new socket if the new socket is active,
 247  *  otherwise we just shortcircuit this and continue with
 248  *  the new socket.
 249  */
 250 int dccp_child_process(struct sock *parent, struct sock *child,
 251                        struct sk_buff *skb)
 252 {
 253         int ret = 0;
 254         const int state = child->sk_state;
 255
 256         if (!sock_owned_by_user(child)) {
 257                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 258                                              skb->len);
 259
 260                 /* Wakeup parent, send SIGIO */
 261                 if (state == DCCP_RESPOND && child->sk_state != state)
 262                         parent->sk_data_ready(parent, 0);
 263         } else {
 264                 /* Alas, it is possible again, because we do lookup
 265                  * in main socket hash table and lock on listening
 266                  * socket does not protect us more.
 267                  */
 268                 sk_add_backlog(child, skb);
 269         }
 270
 271         bh_unlock_sock(child);
 272         sock_put(child);
 273         return ret;
 274 }
 275
 276 EXPORT_SYMBOL_GPL(dccp_child_process);
 277
 278 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 279                          struct request_sock *rsk)
 280 {
 281         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 282 }
 283
 284 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 285
 286 int dccp_reqsk_init(struct request_sock *req,
 287                     struct dccp_sock const *dp, struct sk_buff const *skb)
 288 {
 289         struct dccp_request_sock *dreq = dccp_rsk(req);
 290
 291         inet_rsk(req)->rmt_port   = dccp_hdr(skb)->dccph_sport;
 292         inet_rsk(req)->loc_port   = dccp_hdr(skb)->dccph_dport;
 293         inet_rsk(req)->acked      = 0;
 294         req->rcv_wnd              = sysctl_dccp_feat_sequence_window;
 295         dreq->dreq_timestamp_echo = 0;
 296
 297         /* inherit feature negotiation options from listening socket */
 298         return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 299 }
 300
 301 EXPORT_SYMBOL_GPL(dccp_reqsk_init);