linux/net/dccp/minisocks.c
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   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 *  net/dccp/minisocks.c
   4 *
   5 *  An implementation of the DCCP protocol
   6 *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   7 */
   8
   9#include <linux/dccp.h>
  10#include <linux/gfp.h>
  11#include <linux/kernel.h>
  12#include <linux/skbuff.h>
  13#include <linux/timer.h>
  14
  15#include <net/sock.h>
  16#include <net/xfrm.h>
  17#include <net/inet_timewait_sock.h>
  18
  19#include "ackvec.h"
  20#include "ccid.h"
  21#include "dccp.h"
  22#include "feat.h"
  23
  24struct inet_timewait_death_row dccp_death_row = {
  25        .sysctl_max_tw_buckets = NR_FILE * 2,
  26        .hashinfo       = &dccp_hashinfo,
  27};
  28
  29EXPORT_SYMBOL_GPL(dccp_death_row);
  30
  31void dccp_time_wait(struct sock *sk, int state, int timeo)
  32{
  33        struct inet_timewait_sock *tw;
  34
  35        tw = inet_twsk_alloc(sk, &dccp_death_row, state);
  36
  37        if (tw != NULL) {
  38                const struct inet_connection_sock *icsk = inet_csk(sk);
  39                const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  40#if IS_ENABLED(CONFIG_IPV6)
  41                if (tw->tw_family == PF_INET6) {
  42                        tw->tw_v6_daddr = sk->sk_v6_daddr;
  43                        tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
  44                        tw->tw_ipv6only = sk->sk_ipv6only;
  45                }
  46#endif
  47
  48                /* Get the TIME_WAIT timeout firing. */
  49                if (timeo < rto)
  50                        timeo = rto;
  51
  52                if (state == DCCP_TIME_WAIT)
  53                        timeo = DCCP_TIMEWAIT_LEN;
  54
  55                /* tw_timer is pinned, so we need to make sure BH are disabled
  56                 * in following section, otherwise timer handler could run before
  57                 * we complete the initialization.
  58                 */
  59                local_bh_disable();
  60                inet_twsk_schedule(tw, timeo);
  61                /* Linkage updates.
  62                 * Note that access to tw after this point is illegal.
  63                 */
  64                inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  65                local_bh_enable();
  66        } else {
  67                /* Sorry, if we're out of memory, just CLOSE this
  68                 * socket up.  We've got bigger problems than
  69                 * non-graceful socket closings.
  70                 */
  71                DCCP_WARN("time wait bucket table overflow\n");
  72        }
  73
  74        dccp_done(sk);
  75}
  76
  77struct sock *dccp_create_openreq_child(const struct sock *sk,
  78                                       const struct request_sock *req,
  79                                       const struct sk_buff *skb)
  80{
  81        /*
  82         * Step 3: Process LISTEN state
  83         *
  84         *   (* Generate a new socket and switch to that socket *)
  85         *   Set S := new socket for this port pair
  86         */
  87        struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
  88
  89        if (newsk != NULL) {
  90                struct dccp_request_sock *dreq = dccp_rsk(req);
  91                struct inet_connection_sock *newicsk = inet_csk(newsk);
  92                struct dccp_sock *newdp = dccp_sk(newsk);
  93
  94                newdp->dccps_role           = DCCP_ROLE_SERVER;
  95                newdp->dccps_hc_rx_ackvec   = NULL;
  96                newdp->dccps_service_list   = NULL;
  97                newdp->dccps_service        = dreq->dreq_service;
  98                newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
  99                newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
 100                newicsk->icsk_rto           = DCCP_TIMEOUT_INIT;
 101
 102                INIT_LIST_HEAD(&newdp->dccps_featneg);
 103                /*
 104                 * Step 3: Process LISTEN state
 105                 *
 106                 *    Choose S.ISS (initial seqno) or set from Init Cookies
 107                 *    Initialize S.GAR := S.ISS
 108                 *    Set S.ISR, S.GSR from packet (or Init Cookies)
 109                 *
 110                 *    Setting AWL/AWH and SWL/SWH happens as part of the feature
 111                 *    activation below, as these windows all depend on the local
 112                 *    and remote Sequence Window feature values (7.5.2).
 113                 */
 114                newdp->dccps_iss = dreq->dreq_iss;
 115                newdp->dccps_gss = dreq->dreq_gss;
 116                newdp->dccps_gar = newdp->dccps_iss;
 117                newdp->dccps_isr = dreq->dreq_isr;
 118                newdp->dccps_gsr = dreq->dreq_gsr;
 119
 120                /*
 121                 * Activate features: initialise CCIDs, sequence windows etc.
 122                 */
 123                if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
 124                        sk_free_unlock_clone(newsk);
 125                        return NULL;
 126                }
 127                dccp_init_xmit_timers(newsk);
 128
 129                __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
 130        }
 131        return newsk;
 132}
 133
 134EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 135
 136/*
 137 * Process an incoming packet for RESPOND sockets represented
 138 * as an request_sock.
 139 */
 140struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 141                            struct request_sock *req)
 142{
 143        struct sock *child = NULL;
 144        struct dccp_request_sock *dreq = dccp_rsk(req);
 145        bool own_req;
 146
 147        /* TCP/DCCP listeners became lockless.
 148         * DCCP stores complex state in its request_sock, so we need
 149         * a protection for them, now this code runs without being protected
 150         * by the parent (listener) lock.
 151         */
 152        spin_lock_bh(&dreq->dreq_lock);
 153
 154        /* Check for retransmitted REQUEST */
 155        if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 156
 157                if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
 158                        dccp_pr_debug("Retransmitted REQUEST\n");
 159                        dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
 160                        /*
 161                         * Send another RESPONSE packet
 162                         * To protect against Request floods, increment retrans
 163                         * counter (backoff, monitored by dccp_response_timer).
 164                         */
 165                        inet_rtx_syn_ack(sk, req);
 166                }
 167                /* Network Duplicate, discard packet */
 168                goto out;
 169        }
 170
 171        DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 172
 173        if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 174            dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 175                goto drop;
 176
 177        /* Invalid ACK */
 178        if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 179                                dreq->dreq_iss, dreq->dreq_gss)) {
 180                dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 181                              "dreq_iss=%llu, dreq_gss=%llu\n",
 182                              (unsigned long long)
 183                              DCCP_SKB_CB(skb)->dccpd_ack_seq,
 184                              (unsigned long long) dreq->dreq_iss,
 185                              (unsigned long long) dreq->dreq_gss);
 186                goto drop;
 187        }
 188
 189        if (dccp_parse_options(sk, dreq, skb))
 190                 goto drop;
 191
 192        child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
 193                                                         req, &own_req);
 194        if (child) {
 195                child = inet_csk_complete_hashdance(sk, child, req, own_req);
 196                goto out;
 197        }
 198
 199        DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 200drop:
 201        if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 202                req->rsk_ops->send_reset(sk, skb);
 203
 204        inet_csk_reqsk_queue_drop(sk, req);
 205out:
 206        spin_unlock_bh(&dreq->dreq_lock);
 207        return child;
 208}
 209
 210EXPORT_SYMBOL_GPL(dccp_check_req);
 211
 212/*
 213 *  Queue segment on the new socket if the new socket is active,
 214 *  otherwise we just shortcircuit this and continue with
 215 *  the new socket.
 216 */
 217int dccp_child_process(struct sock *parent, struct sock *child,
 218                       struct sk_buff *skb)
 219        __releases(child)
 220{
 221        int ret = 0;
 222        const int state = child->sk_state;
 223
 224        if (!sock_owned_by_user(child)) {
 225                ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 226                                             skb->len);
 227
 228                /* Wakeup parent, send SIGIO */
 229                if (state == DCCP_RESPOND && child->sk_state != state)
 230                        parent->sk_data_ready(parent);
 231        } else {
 232                /* Alas, it is possible again, because we do lookup
 233                 * in main socket hash table and lock on listening
 234                 * socket does not protect us more.
 235                 */
 236                __sk_add_backlog(child, skb);
 237        }
 238
 239        bh_unlock_sock(child);
 240        sock_put(child);
 241        return ret;
 242}
 243
 244EXPORT_SYMBOL_GPL(dccp_child_process);
 245
 246void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 247                         struct request_sock *rsk)
 248{
 249        DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 250}
 251
 252EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 253
 254int dccp_reqsk_init(struct request_sock *req,
 255                    struct dccp_sock const *dp, struct sk_buff const *skb)
 256{
 257        struct dccp_request_sock *dreq = dccp_rsk(req);
 258
 259        spin_lock_init(&dreq->dreq_lock);
 260        inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
 261        inet_rsk(req)->ir_num      = ntohs(dccp_hdr(skb)->dccph_dport);
 262        inet_rsk(req)->acked       = 0;
 263        dreq->dreq_timestamp_echo  = 0;
 264
 265        /* inherit feature negotiation options from listening socket */
 266        return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 267}
 268
 269EXPORT_SYMBOL_GPL(dccp_reqsk_init);
 270