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/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
  28 struct 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
  44 EXPORT_SYMBOL_GPL(dccp_death_row);
  45
  46 void 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                         tw->tw_v6_daddr = sk->sk_v6_daddr;
  59                         tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
  60                         tw->tw_ipv6only = sk->sk_ipv6only;
  61                 }
  62 #endif
  63                 /* Linkage updates. */
  64                 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  65
  66                 /* Get the TIME_WAIT timeout firing. */
  67                 if (timeo < rto)
  68                         timeo = rto;
  69
  70                 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
  71                 if (state == DCCP_TIME_WAIT)
  72                         timeo = DCCP_TIMEWAIT_LEN;
  73
  74                 inet_twsk_schedule(tw, &dccp_death_row, timeo,
  75                                    DCCP_TIMEWAIT_LEN);
  76                 inet_twsk_put(tw);
  77         } else {
  78                 /* Sorry, if we're out of memory, just CLOSE this
  79                  * socket up.  We've got bigger problems than
  80                  * non-graceful socket closings.
  81                  */
  82                 DCCP_WARN("time wait bucket table overflow\n");
  83         }
  84
  85         dccp_done(sk);
  86 }
  87
  88 struct sock *dccp_create_openreq_child(struct sock *sk,
  89                                        const struct request_sock *req,
  90                                        const struct sk_buff *skb)
  91 {
  92         /*
  93          * Step 3: Process LISTEN state
  94          *
  95          *   (* Generate a new socket and switch to that socket *)
  96          *   Set S := new socket for this port pair
  97          */
  98         struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
  99
 100         if (newsk != NULL) {
 101                 struct dccp_request_sock *dreq = dccp_rsk(req);
 102                 struct inet_connection_sock *newicsk = inet_csk(newsk);
 103                 struct dccp_sock *newdp = dccp_sk(newsk);
 104
 105                 newdp->dccps_role           = DCCP_ROLE_SERVER;
 106                 newdp->dccps_hc_rx_ackvec   = NULL;
 107                 newdp->dccps_service_list   = NULL;
 108                 newdp->dccps_service        = dreq->dreq_service;
 109                 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
 110                 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
 111                 newicsk->icsk_rto           = DCCP_TIMEOUT_INIT;
 112
 113                 INIT_LIST_HEAD(&newdp->dccps_featneg);
 114                 /*
 115                  * Step 3: Process LISTEN state
 116                  *
 117                  *    Choose S.ISS (initial seqno) or set from Init Cookies
 118                  *    Initialize S.GAR := S.ISS
 119                  *    Set S.ISR, S.GSR from packet (or Init Cookies)
 120                  *
 121                  *    Setting AWL/AWH and SWL/SWH happens as part of the feature
 122                  *    activation below, as these windows all depend on the local
 123                  *    and remote Sequence Window feature values (7.5.2).
 124                  */
 125                 newdp->dccps_iss = dreq->dreq_iss;
 126                 newdp->dccps_gss = dreq->dreq_gss;
 127                 newdp->dccps_gar = newdp->dccps_iss;
 128                 newdp->dccps_isr = dreq->dreq_isr;
 129                 newdp->dccps_gsr = dreq->dreq_gsr;
 130
 131                 /*
 132                  * Activate features: initialise CCIDs, sequence windows etc.
 133                  */
 134                 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
 135                         /* It is still raw copy of parent, so invalidate
 136                          * destructor and make plain sk_free() */
 137                         newsk->sk_destruct = NULL;
 138                         sk_free(newsk);
 139                         return NULL;
 140                 }
 141                 dccp_init_xmit_timers(newsk);
 142
 143                 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
 144         }
 145         return newsk;
 146 }
 147
 148 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 149
 150 /*
 151  * Process an incoming packet for RESPOND sockets represented
 152  * as an request_sock.
 153  */
 154 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 155                             struct request_sock *req)
 156 {
 157         struct sock *child = NULL;
 158         struct dccp_request_sock *dreq = dccp_rsk(req);
 159
 160         /* Check for retransmitted REQUEST */
 161         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 162
 163                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
 164                         dccp_pr_debug("Retransmitted REQUEST\n");
 165                         dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
 166                         /*
 167                          * Send another RESPONSE packet
 168                          * To protect against Request floods, increment retrans
 169                          * counter (backoff, monitored by dccp_response_timer).
 170                          */
 171                         inet_rtx_syn_ack(sk, req);
 172                 }
 173                 /* Network Duplicate, discard packet */
 174                 return NULL;
 175         }
 176
 177         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 178
 179         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 180             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 181                 goto drop;
 182
 183         /* Invalid ACK */
 184         if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 185                                 dreq->dreq_iss, dreq->dreq_gss)) {
 186                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 187                               "dreq_iss=%llu, dreq_gss=%llu\n",
 188                               (unsigned long long)
 189                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 190                               (unsigned long long) dreq->dreq_iss,
 191                               (unsigned long long) dreq->dreq_gss);
 192                 goto drop;
 193         }
 194
 195         if (dccp_parse_options(sk, dreq, skb))
 196                  goto drop;
 197
 198         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 199         if (child == NULL)
 200                 goto listen_overflow;
 201
 202         inet_csk_reqsk_queue_unlink(sk, req);
 203         inet_csk_reqsk_queue_removed(sk, req);
 204         inet_csk_reqsk_queue_add(sk, req, child);
 205 out:
 206         return child;
 207 listen_overflow:
 208         dccp_pr_debug("listen_overflow!\n");
 209         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 210 drop:
 211         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 212                 req->rsk_ops->send_reset(sk, skb);
 213
 214         inet_csk_reqsk_queue_drop(sk, req);
 215         goto out;
 216 }
 217
 218 EXPORT_SYMBOL_GPL(dccp_check_req);
 219
 220 /*
 221  *  Queue segment on the new socket if the new socket is active,
 222  *  otherwise we just shortcircuit this and continue with
 223  *  the new socket.
 224  */
 225 int dccp_child_process(struct sock *parent, struct sock *child,
 226                        struct sk_buff *skb)
 227 {
 228         int ret = 0;
 229         const int state = child->sk_state;
 230
 231         if (!sock_owned_by_user(child)) {
 232                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 233                                              skb->len);
 234
 235                 /* Wakeup parent, send SIGIO */
 236                 if (state == DCCP_RESPOND && child->sk_state != state)
 237                         parent->sk_data_ready(parent);
 238         } else {
 239                 /* Alas, it is possible again, because we do lookup
 240                  * in main socket hash table and lock on listening
 241                  * socket does not protect us more.
 242                  */
 243                 __sk_add_backlog(child, skb);
 244         }
 245
 246         bh_unlock_sock(child);
 247         sock_put(child);
 248         return ret;
 249 }
 250
 251 EXPORT_SYMBOL_GPL(dccp_child_process);
 252
 253 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 254                          struct request_sock *rsk)
 255 {
 256         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 257 }
 258
 259 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 260
 261 int dccp_reqsk_init(struct request_sock *req,
 262                     struct dccp_sock const *dp, struct sk_buff const *skb)
 263 {
 264         struct dccp_request_sock *dreq = dccp_rsk(req);
 265
 266         inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
 267         inet_rsk(req)->ir_num      = ntohs(dccp_hdr(skb)->dccph_dport);
 268         inet_rsk(req)->acked       = 0;
 269         dreq->dreq_timestamp_echo  = 0;
 270
 271         /* inherit feature negotiation options from listening socket */
 272         return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 273 }
 274
 275 EXPORT_SYMBOL_GPL(dccp_reqsk_init);