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                         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
  93 struct 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
 153 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 154
 155 /*
 156  * Process an incoming packet for RESPOND sockets represented
 157  * as an request_sock.
 158  */
 159 struct 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                         inet_rtx_syn_ack(sk, req);
 178                 }
 179                 /* Network Duplicate, discard packet */
 180                 return NULL;
 181         }
 182
 183         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 184
 185         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 186             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 187                 goto drop;
 188
 189         /* Invalid ACK */
 190         if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 191                                 dreq->dreq_iss, dreq->dreq_gss)) {
 192                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 193                               "dreq_iss=%llu, dreq_gss=%llu\n",
 194                               (unsigned long long)
 195                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 196                               (unsigned long long) dreq->dreq_iss,
 197                               (unsigned long long) dreq->dreq_gss);
 198                 goto drop;
 199         }
 200
 201         if (dccp_parse_options(sk, dreq, skb))
 202                  goto drop;
 203
 204         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
 205         if (child == NULL)
 206                 goto listen_overflow;
 207
 208         inet_csk_reqsk_queue_unlink(sk, req, prev);
 209         inet_csk_reqsk_queue_removed(sk, req);
 210         inet_csk_reqsk_queue_add(sk, req, child);
 211 out:
 212         return child;
 213 listen_overflow:
 214         dccp_pr_debug("listen_overflow!\n");
 215         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 216 drop:
 217         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 218                 req->rsk_ops->send_reset(sk, skb);
 219
 220         inet_csk_reqsk_queue_drop(sk, req, prev);
 221         goto out;
 222 }
 223
 224 EXPORT_SYMBOL_GPL(dccp_check_req);
 225
 226 /*
 227  *  Queue segment on the new socket if the new socket is active,
 228  *  otherwise we just shortcircuit this and continue with
 229  *  the new socket.
 230  */
 231 int dccp_child_process(struct sock *parent, struct sock *child,
 232                        struct sk_buff *skb)
 233 {
 234         int ret = 0;
 235         const int state = child->sk_state;
 236
 237         if (!sock_owned_by_user(child)) {
 238                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 239                                              skb->len);
 240
 241                 /* Wakeup parent, send SIGIO */
 242                 if (state == DCCP_RESPOND && child->sk_state != state)
 243                         parent->sk_data_ready(parent, 0);
 244         } else {
 245                 /* Alas, it is possible again, because we do lookup
 246                  * in main socket hash table and lock on listening
 247                  * socket does not protect us more.
 248                  */
 249                 __sk_add_backlog(child, skb);
 250         }
 251
 252         bh_unlock_sock(child);
 253         sock_put(child);
 254         return ret;
 255 }
 256
 257 EXPORT_SYMBOL_GPL(dccp_child_process);
 258
 259 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
 260                          struct request_sock *rsk)
 261 {
 262         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 263 }
 264
 265 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 266
 267 int dccp_reqsk_init(struct request_sock *req,
 268                     struct dccp_sock const *dp, struct sk_buff const *skb)
 269 {
 270         struct dccp_request_sock *dreq = dccp_rsk(req);
 271
 272         inet_rsk(req)->rmt_port   = dccp_hdr(skb)->dccph_sport;
 273         inet_rsk(req)->loc_port   = dccp_hdr(skb)->dccph_dport;
 274         inet_rsk(req)->acked      = 0;
 275         dreq->dreq_timestamp_echo = 0;
 276
 277         /* inherit feature negotiation options from listening socket */
 278         return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 279 }
 280
 281 EXPORT_SYMBOL_GPL(dccp_reqsk_init);