linux/net/dccp/minisocks.c
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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/gfp.h>
  15#include <linux/kernel.h>
  16#include <linux/skbuff.h>
  17#include <linux/timer.h>
  18
  19#include <net/sock.h>
  20#include <net/xfrm.h>
  21#include <net/inet_timewait_sock.h>
  22
  23#include "ackvec.h"
  24#include "ccid.h"
  25#include "dccp.h"
  26#include "feat.h"
  27
  28struct inet_timewait_death_row dccp_death_row = {
  29        .sysctl_max_tw_buckets = NR_FILE * 2,
  30        .period         = DCCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS,
  31        .death_lock     = __SPIN_LOCK_UNLOCKED(dccp_death_row.death_lock),
  32        .hashinfo       = &dccp_hashinfo,
  33        .tw_timer       = TIMER_INITIALIZER(inet_twdr_hangman, 0,
  34                                            (unsigned long)&dccp_death_row),
  35        .twkill_work    = __WORK_INITIALIZER(dccp_death_row.twkill_work,
  36                                             inet_twdr_twkill_work),
  37/* Short-time timewait calendar */
  38
  39        .twcal_hand     = -1,
  40        .twcal_timer    = TIMER_INITIALIZER(inet_twdr_twcal_tick, 0,
  41                                            (unsigned long)&dccp_death_row),
  42};
  43
  44EXPORT_SYMBOL_GPL(dccp_death_row);
  45
  46void dccp_time_wait(struct sock *sk, int state, int timeo)
  47{
  48        struct inet_timewait_sock *tw = NULL;
  49
  50        if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
  51                tw = inet_twsk_alloc(sk, state);
  52
  53        if (tw != NULL) {
  54                const struct inet_connection_sock *icsk = inet_csk(sk);
  55                const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  56#if IS_ENABLED(CONFIG_IPV6)
  57                if (tw->tw_family == PF_INET6) {
  58                        const struct ipv6_pinfo *np = inet6_sk(sk);
  59                        struct inet6_timewait_sock *tw6;
  60
  61                        tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot);
  62                        tw6 = inet6_twsk((struct sock *)tw);
  63                        tw6->tw_v6_daddr = np->daddr;
  64                        tw6->tw_v6_rcv_saddr = np->rcv_saddr;
  65                        tw->tw_ipv6only = np->ipv6only;
  66                }
  67#endif
  68                /* Linkage updates. */
  69                __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  70
  71                /* Get the TIME_WAIT timeout firing. */
  72                if (timeo < rto)
  73                        timeo = rto;
  74
  75                tw->tw_timeout = DCCP_TIMEWAIT_LEN;
  76                if (state == DCCP_TIME_WAIT)
  77                        timeo = DCCP_TIMEWAIT_LEN;
  78
  79                inet_twsk_schedule(tw, &dccp_death_row, timeo,
  80                                   DCCP_TIMEWAIT_LEN);
  81                inet_twsk_put(tw);
  82        } else {
  83                /* Sorry, if we're out of memory, just CLOSE this
  84                 * socket up.  We've got bigger problems than
  85                 * non-graceful socket closings.
  86                 */
  87                DCCP_WARN("time wait bucket table overflow\n");
  88        }
  89
  90        dccp_done(sk);
  91}
  92
  93struct sock *dccp_create_openreq_child(struct sock *sk,
  94                                       const struct request_sock *req,
  95                                       const struct sk_buff *skb)
  96{
  97        /*
  98         * Step 3: Process LISTEN state
  99         *
 100         *   (* Generate a new socket and switch to that socket *)
 101         *   Set S := new socket for this port pair
 102         */
 103        struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
 104
 105        if (newsk != NULL) {
 106                struct dccp_request_sock *dreq = dccp_rsk(req);
 107                struct inet_connection_sock *newicsk = inet_csk(newsk);
 108                struct dccp_sock *newdp = dccp_sk(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                newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
 115                newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
 116                newicsk->icsk_rto           = DCCP_TIMEOUT_INIT;
 117
 118                INIT_LIST_HEAD(&newdp->dccps_featneg);
 119                /*
 120                 * Step 3: Process LISTEN state
 121                 *
 122                 *    Choose S.ISS (initial seqno) or set from Init Cookies
 123                 *    Initialize S.GAR := S.ISS
 124                 *    Set S.ISR, S.GSR from packet (or Init Cookies)
 125                 *
 126                 *    Setting AWL/AWH and SWL/SWH happens as part of the feature
 127                 *    activation below, as these windows all depend on the local
 128                 *    and remote Sequence Window feature values (7.5.2).
 129                 */
 130                newdp->dccps_iss = dreq->dreq_iss;
 131                newdp->dccps_gss = dreq->dreq_gss;
 132                newdp->dccps_gar = newdp->dccps_iss;
 133                newdp->dccps_isr = dreq->dreq_isr;
 134                newdp->dccps_gsr = dreq->dreq_gsr;
 135
 136                /*
 137                 * Activate features: initialise CCIDs, sequence windows etc.
 138                 */
 139                if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
 140                        /* It is still raw copy of parent, so invalidate
 141                         * destructor and make plain sk_free() */
 142                        newsk->sk_destruct = NULL;
 143                        sk_free(newsk);
 144                        return NULL;
 145                }
 146                dccp_init_xmit_timers(newsk);
 147
 148                DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
 149        }
 150        return newsk;
 151}
 152
 153EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 154
 155/*
 156 * Process an incoming packet for RESPOND sockets represented
 157 * as an request_sock.
 158 */
 159struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 160                            struct request_sock *req,
 161                            struct request_sock **prev)
 162{
 163        struct sock *child = NULL;
 164        struct dccp_request_sock *dreq = dccp_rsk(req);
 165
 166        /* Check for retransmitted REQUEST */
 167        if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 168
 169                if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
 170                        dccp_pr_debug("Retransmitted REQUEST\n");
 171                        dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
 172                        /*
 173                         * Send another RESPONSE packet
 174                         * To protect against Request floods, increment retrans
 175                         * counter (backoff, monitored by dccp_response_timer).
 176                         */
 177                        req->retrans++;
 178                        req->rsk_ops->rtx_syn_ack(sk, req, NULL);
 179                }
 180                /* Network Duplicate, discard packet */
 181                return NULL;
 182        }
 183
 184        DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 185
 186        if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 187            dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 188                goto drop;
 189
 190        /* Invalid ACK */
 191        if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 192                                dreq->dreq_iss, dreq->dreq_gss)) {
 193                dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 194                              "dreq_iss=%llu, dreq_gss=%llu\n",
 195                              (unsigned long long)
 196                              DCCP_SKB_CB(skb)->dccpd_ack_seq,
 197                              (unsigned long long) dreq->dreq_iss,
 198                              (unsigned long long) dreq->dreq_gss);
 199                goto drop;
 200        }
 201
 202        if (dccp_parse_options(sk, dreq, skb))
 203                 goto drop;
 204
 205        child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 206        if (child == NULL)
 207                goto listen_overflow;
 208
 209        inet_csk_reqsk_queue_unlink(sk, req, prev);
 210        inet_csk_reqsk_queue_removed(sk, req);
 211        inet_csk_reqsk_queue_add(sk, req, child);
 212out:
 213        return child;
 214listen_overflow:
 215        dccp_pr_debug("listen_overflow!\n");
 216        DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 217drop:
 218        if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 219                req->rsk_ops->send_reset(sk, skb);
 220
 221        inet_csk_reqsk_queue_drop(sk, req, prev);
 222        goto out;
 223}
 224
 225EXPORT_SYMBOL_GPL(dccp_check_req);
 226
 227/*
 228 *  Queue segment on the new socket if the new socket is active,
 229 *  otherwise we just shortcircuit this and continue with
 230 *  the new socket.
 231 */
 232int dccp_child_process(struct sock *parent, struct sock *child,
 233                       struct sk_buff *skb)
 234{
 235        int ret = 0;
 236        const int state = child->sk_state;
 237
 238        if (!sock_owned_by_user(child)) {
 239                ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 240                                             skb->len);
 241
 242                /* Wakeup parent, send SIGIO */
 243                if (state == DCCP_RESPOND && child->sk_state != state)
 244                        parent->sk_data_ready(parent, 0);
 245        } else {
 246                /* Alas, it is possible again, because we do lookup
 247                 * in main socket hash table and lock on listening
 248                 * socket does not protect us more.
 249                 */
 250                __sk_add_backlog(child, skb);
 251        }
 252
 253        bh_unlock_sock(child);
 254        sock_put(child);
 255        return ret;
 256}
 257
 258EXPORT_SYMBOL_GPL(dccp_child_process);
 259
 260void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 261                         struct request_sock *rsk)
 262{
 263        DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 264}
 265
 266EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 267
 268int dccp_reqsk_init(struct request_sock *req,
 269                    struct dccp_sock const *dp, struct sk_buff const *skb)
 270{
 271        struct dccp_request_sock *dreq = dccp_rsk(req);
 272
 273        inet_rsk(req)->rmt_port   = dccp_hdr(skb)->dccph_sport;
 274        inet_rsk(req)->loc_port   = dccp_hdr(skb)->dccph_dport;
 275        inet_rsk(req)->acked      = 0;
 276        dreq->dreq_timestamp_echo = 0;
 277
 278        /* inherit feature negotiation options from listening socket */
 279        return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 280}
 281
 282EXPORT_SYMBOL_GPL(dccp_reqsk_init);
 283
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