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_minisock_init(struct dccp_minisock *dmsk)
  46 {
  47         dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
  48         dmsk->dccpms_rx_ccid         = sysctl_dccp_feat_rx_ccid;
  49         dmsk->dccpms_tx_ccid         = sysctl_dccp_feat_tx_ccid;
  50         dmsk->dccpms_ack_ratio       = sysctl_dccp_feat_ack_ratio;
  51         dmsk->dccpms_send_ack_vector = sysctl_dccp_feat_send_ack_vector;
  52         dmsk->dccpms_send_ndp_count  = sysctl_dccp_feat_send_ndp_count;
  53 }
  54
  55 void dccp_time_wait(struct sock *sk, int state, int timeo)
  56 {
  57         struct inet_timewait_sock *tw = NULL;
  58
  59         if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
  60                 tw = inet_twsk_alloc(sk, state);
  61
  62         if (tw != NULL) {
  63                 const struct inet_connection_sock *icsk = inet_csk(sk);
  64                 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  65 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
  66                 if (tw->tw_family == PF_INET6) {
  67                         const struct ipv6_pinfo *np = inet6_sk(sk);
  68                         struct inet6_timewait_sock *tw6;
  69
  70                         tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot);
  71                         tw6 = inet6_twsk((struct sock *)tw);
  72                         ipv6_addr_copy(&tw6->tw_v6_daddr, &np->daddr);
  73                         ipv6_addr_copy(&tw6->tw_v6_rcv_saddr, &np->rcv_saddr);
  74                         tw->tw_ipv6only = np->ipv6only;
  75                 }
  76 #endif
  77                 /* Linkage updates. */
  78                 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  79
  80                 /* Get the TIME_WAIT timeout firing. */
  81                 if (timeo < rto)
  82                         timeo = rto;
  83
  84                 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
  85                 if (state == DCCP_TIME_WAIT)
  86                         timeo = DCCP_TIMEWAIT_LEN;
  87
  88                 inet_twsk_schedule(tw, &dccp_death_row, timeo,
  89                                    DCCP_TIMEWAIT_LEN);
  90                 inet_twsk_put(tw);
  91         } else {
  92                 /* Sorry, if we're out of memory, just CLOSE this
  93                  * socket up.  We've got bigger problems than
  94                  * non-graceful socket closings.
  95                  */
  96                 DCCP_WARN("time wait bucket table overflow\n");
  97         }
  98
  99         dccp_done(sk);
 100 }
 101
 102 struct sock *dccp_create_openreq_child(struct sock *sk,
 103                                        const struct request_sock *req,
 104                                        const struct sk_buff *skb)
 105 {
 106         /*
 107          * Step 3: Process LISTEN state
 108          *
 109          *   (* Generate a new socket and switch to that socket *)
 110          *   Set S := new socket for this port pair
 111          */
 112         struct sock *newsk = inet_csk_clone(sk, req, GFP_ATOMIC);
 113
 114         if (newsk != NULL) {
 115                 const struct dccp_request_sock *dreq = dccp_rsk(req);
 116                 struct inet_connection_sock *newicsk = inet_csk(newsk);
 117                 struct dccp_sock *newdp = dccp_sk(newsk);
 118                 struct dccp_minisock *newdmsk = dccp_msk(newsk);
 119
 120                 newdp->dccps_role           = DCCP_ROLE_SERVER;
 121                 newdp->dccps_hc_rx_ackvec   = NULL;
 122                 newdp->dccps_service_list   = NULL;
 123                 newdp->dccps_service        = dreq->dreq_service;
 124                 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
 125                 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
 126                 newicsk->icsk_rto           = DCCP_TIMEOUT_INIT;
 127
 128                 if (dccp_feat_clone(sk, newsk))
 129                         goto out_free;
 130
 131                 if (newdmsk->dccpms_send_ack_vector) {
 132                         newdp->dccps_hc_rx_ackvec =
 133                                                 dccp_ackvec_alloc(GFP_ATOMIC);
 134                         if (unlikely(newdp->dccps_hc_rx_ackvec == NULL))
 135                                 goto out_free;
 136                 }
 137
 138                 newdp->dccps_hc_rx_ccid =
 139                             ccid_hc_rx_new(newdmsk->dccpms_rx_ccid,
 140                                            newsk, GFP_ATOMIC);
 141                 newdp->dccps_hc_tx_ccid =
 142                             ccid_hc_tx_new(newdmsk->dccpms_tx_ccid,
 143                                            newsk, GFP_ATOMIC);
 144                 if (unlikely(newdp->dccps_hc_rx_ccid == NULL ||
 145                              newdp->dccps_hc_tx_ccid == NULL)) {
 146                         dccp_ackvec_free(newdp->dccps_hc_rx_ackvec);
 147                         ccid_hc_rx_delete(newdp->dccps_hc_rx_ccid, newsk);
 148                         ccid_hc_tx_delete(newdp->dccps_hc_tx_ccid, newsk);
 149 out_free:
 150                         /* It is still raw copy of parent, so invalidate
 151                          * destructor and make plain sk_free() */
 152                         newsk->sk_destruct = NULL;
 153                         sk_free(newsk);
 154                         return NULL;
 155                 }
 156
 157                 /*
 158                  * Step 3: Process LISTEN state
 159                  *
 160                  *    Choose S.ISS (initial seqno) or set from Init Cookies
 161                  *    Initialize S.GAR := S.ISS
 162                  *    Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
 163                  */
 164
 165                 /* See dccp_v4_conn_request */
 166                 newdmsk->dccpms_sequence_window = req->rcv_wnd;
 167
 168                 newdp->dccps_gar = newdp->dccps_iss = dreq->dreq_iss;
 169                 dccp_update_gss(newsk, dreq->dreq_iss);
 170
 171                 newdp->dccps_isr = dreq->dreq_isr;
 172                 dccp_update_gsr(newsk, dreq->dreq_isr);
 173
 174                 /*
 175                  * SWL and AWL are initially adjusted so that they are not less than
 176                  * the initial Sequence Numbers received and sent, respectively:
 177                  *      SWL := max(GSR + 1 - floor(W/4), ISR),
 178                  *      AWL := max(GSS - W' + 1, ISS).
 179                  * These adjustments MUST be applied only at the beginning of the
 180                  * connection.
 181                  */
 182                 dccp_set_seqno(&newdp->dccps_swl,
 183                                max48(newdp->dccps_swl, newdp->dccps_isr));
 184                 dccp_set_seqno(&newdp->dccps_awl,
 185                                max48(newdp->dccps_awl, newdp->dccps_iss));
 186
 187                 dccp_init_xmit_timers(newsk);
 188
 189                 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
 190         }
 191         return newsk;
 192 }
 193
 194 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 195
 196 /*
 197  * Process an incoming packet for RESPOND sockets represented
 198  * as an request_sock.
 199  */
 200 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 201                             struct request_sock *req,
 202                             struct request_sock **prev)
 203 {
 204         struct sock *child = NULL;
 205         struct dccp_request_sock *dreq = dccp_rsk(req);
 206
 207         /* Check for retransmitted REQUEST */
 208         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 209
 210                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_isr)) {
 211                         dccp_pr_debug("Retransmitted REQUEST\n");
 212                         dreq->dreq_isr = DCCP_SKB_CB(skb)->dccpd_seq;
 213                         /*
 214                          * Send another RESPONSE packet
 215                          * To protect against Request floods, increment retrans
 216                          * counter (backoff, monitored by dccp_response_timer).
 217                          */
 218                         req->retrans++;
 219                         req->rsk_ops->rtx_syn_ack(sk, req);
 220                 }
 221                 /* Network Duplicate, discard packet */
 222                 return NULL;
 223         }
 224
 225         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 226
 227         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 228             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 229                 goto drop;
 230
 231         /* Invalid ACK */
 232         if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dreq->dreq_iss) {
 233                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 234                               "dreq_iss=%llu\n",
 235                               (unsigned long long)
 236                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 237                               (unsigned long long) dreq->dreq_iss);
 238                 goto drop;
 239         }
 240
 241         if (dccp_parse_options(sk, dreq, skb))
 242                  goto drop;
 243
 244         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 245         if (child == NULL)
 246                 goto listen_overflow;
 247
 248         inet_csk_reqsk_queue_unlink(sk, req, prev);
 249         inet_csk_reqsk_queue_removed(sk, req);
 250         inet_csk_reqsk_queue_add(sk, req, child);
 251 out:
 252         return child;
 253 listen_overflow:
 254         dccp_pr_debug("listen_overflow!\n");
 255         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 256 drop:
 257         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 258                 req->rsk_ops->send_reset(sk, skb);
 259
 260         inet_csk_reqsk_queue_drop(sk, req, prev);
 261         goto out;
 262 }
 263
 264 EXPORT_SYMBOL_GPL(dccp_check_req);
 265
 266 /*
 267  *  Queue segment on the new socket if the new socket is active,
 268  *  otherwise we just shortcircuit this and continue with
 269  *  the new socket.
 270  */
 271 int dccp_child_process(struct sock *parent, struct sock *child,
 272                        struct sk_buff *skb)
 273 {
 274         int ret = 0;
 275         const int state = child->sk_state;
 276
 277         if (!sock_owned_by_user(child)) {
 278                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 279                                              skb->len);
 280
 281                 /* Wakeup parent, send SIGIO */
 282                 if (state == DCCP_RESPOND && child->sk_state != state)
 283                         parent->sk_data_ready(parent, 0);
 284         } else {
 285                 /* Alas, it is possible again, because we do lookup
 286                  * in main socket hash table and lock on listening
 287                  * socket does not protect us more.
 288                  */
 289                 sk_add_backlog(child, skb);
 290         }
 291
 292         bh_unlock_sock(child);
 293         sock_put(child);
 294         return ret;
 295 }
 296
 297 EXPORT_SYMBOL_GPL(dccp_child_process);
 298
 299 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 300                          struct request_sock *rsk)
 301 {
 302         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 303 }
 304
 305 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 306
 307 void dccp_reqsk_init(struct request_sock *req, struct sk_buff *skb)
 308 {
 309         struct dccp_request_sock *dreq = dccp_rsk(req);
 310
 311         inet_rsk(req)->rmt_port   = dccp_hdr(skb)->dccph_sport;
 312         inet_rsk(req)->acked      = 0;
 313         req->rcv_wnd              = sysctl_dccp_feat_sequence_window;
 314         dreq->dreq_timestamp_echo = 0;
 315 }
 316
 317 EXPORT_SYMBOL_GPL(dccp_reqsk_init);