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         .hashinfo       = &dccp_hashinfo,
  31 };
  32
  33 EXPORT_SYMBOL_GPL(dccp_death_row);
  34
  35 void dccp_time_wait(struct sock *sk, int state, int timeo)
  36 {
  37         struct inet_timewait_sock *tw;
  38
  39         tw = inet_twsk_alloc(sk, &dccp_death_row, state);
  40
  41         if (tw != NULL) {
  42                 const struct inet_connection_sock *icsk = inet_csk(sk);
  43                 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  44 #if IS_ENABLED(CONFIG_IPV6)
  45                 if (tw->tw_family == PF_INET6) {
  46                         tw->tw_v6_daddr = sk->sk_v6_daddr;
  47                         tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
  48                         tw->tw_ipv6only = sk->sk_ipv6only;
  49                 }
  50 #endif
  51
  52                 /* Get the TIME_WAIT timeout firing. */
  53                 if (timeo < rto)
  54                         timeo = rto;
  55
  56                 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
  57                 if (state == DCCP_TIME_WAIT)
  58                         timeo = DCCP_TIMEWAIT_LEN;
  59
  60                 /* tw_timer is pinned, so we need to make sure BH are disabled
  61                  * in following section, otherwise timer handler could run before
  62                  * we complete the initialization.
  63                  */
  64                 local_bh_disable();
  65                 inet_twsk_schedule(tw, timeo);
  66                 /* Linkage updates.
  67                  * Note that access to tw after this point is illegal.
  68                  */
  69                 inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  70                 local_bh_enable();
  71         } else {
  72                 /* Sorry, if we're out of memory, just CLOSE this
  73                  * socket up.  We've got bigger problems than
  74                  * non-graceful socket closings.
  75                  */
  76                 DCCP_WARN("time wait bucket table overflow\n");
  77         }
  78
  79         dccp_done(sk);
  80 }
  81
  82 struct sock *dccp_create_openreq_child(const struct sock *sk,
  83                                        const struct request_sock *req,
  84                                        const struct sk_buff *skb)
  85 {
  86         /*
  87          * Step 3: Process LISTEN state
  88          *
  89          *   (* Generate a new socket and switch to that socket *)
  90          *   Set S := new socket for this port pair
  91          */
  92         struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
  93
  94         if (newsk != NULL) {
  95                 struct dccp_request_sock *dreq = dccp_rsk(req);
  96                 struct inet_connection_sock *newicsk = inet_csk(newsk);
  97                 struct dccp_sock *newdp = dccp_sk(newsk);
  98
  99                 newdp->dccps_role           = DCCP_ROLE_SERVER;
 100                 newdp->dccps_hc_rx_ackvec   = NULL;
 101                 newdp->dccps_service_list   = NULL;
 102                 newdp->dccps_service        = dreq->dreq_service;
 103                 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
 104                 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
 105                 newicsk->icsk_rto           = DCCP_TIMEOUT_INIT;
 106
 107                 INIT_LIST_HEAD(&newdp->dccps_featneg);
 108                 /*
 109                  * Step 3: Process LISTEN state
 110                  *
 111                  *    Choose S.ISS (initial seqno) or set from Init Cookies
 112                  *    Initialize S.GAR := S.ISS
 113                  *    Set S.ISR, S.GSR from packet (or Init Cookies)
 114                  *
 115                  *    Setting AWL/AWH and SWL/SWH happens as part of the feature
 116                  *    activation below, as these windows all depend on the local
 117                  *    and remote Sequence Window feature values (7.5.2).
 118                  */
 119                 newdp->dccps_iss = dreq->dreq_iss;
 120                 newdp->dccps_gss = dreq->dreq_gss;
 121                 newdp->dccps_gar = newdp->dccps_iss;
 122                 newdp->dccps_isr = dreq->dreq_isr;
 123                 newdp->dccps_gsr = dreq->dreq_gsr;
 124
 125                 /*
 126                  * Activate features: initialise CCIDs, sequence windows etc.
 127                  */
 128                 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
 129                         sk_free_unlock_clone(newsk);
 130                         return NULL;
 131                 }
 132                 dccp_init_xmit_timers(newsk);
 133
 134                 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
 135         }
 136         return newsk;
 137 }
 138
 139 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 140
 141 /*
 142  * Process an incoming packet for RESPOND sockets represented
 143  * as an request_sock.
 144  */
 145 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 146                             struct request_sock *req)
 147 {
 148         struct sock *child = NULL;
 149         struct dccp_request_sock *dreq = dccp_rsk(req);
 150         bool own_req;
 151
 152         /* TCP/DCCP listeners became lockless.
 153          * DCCP stores complex state in its request_sock, so we need
 154          * a protection for them, now this code runs without being protected
 155          * by the parent (listener) lock.
 156          */
 157         spin_lock_bh(&dreq->dreq_lock);
 158
 159         /* Check for retransmitted REQUEST */
 160         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 161
 162                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
 163                         dccp_pr_debug("Retransmitted REQUEST\n");
 164                         dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
 165                         /*
 166                          * Send another RESPONSE packet
 167                          * To protect against Request floods, increment retrans
 168                          * counter (backoff, monitored by dccp_response_timer).
 169                          */
 170                         inet_rtx_syn_ack(sk, req);
 171                 }
 172                 /* Network Duplicate, discard packet */
 173                 goto out;
 174         }
 175
 176         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 177
 178         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 179             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 180                 goto drop;
 181
 182         /* Invalid ACK */
 183         if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 184                                 dreq->dreq_iss, dreq->dreq_gss)) {
 185                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 186                               "dreq_iss=%llu, dreq_gss=%llu\n",
 187                               (unsigned long long)
 188                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 189                               (unsigned long long) dreq->dreq_iss,
 190                               (unsigned long long) dreq->dreq_gss);
 191                 goto drop;
 192         }
 193
 194         if (dccp_parse_options(sk, dreq, skb))
 195                  goto drop;
 196
 197         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
 198                                                          req, &own_req);
 199         if (child) {
 200                 child = inet_csk_complete_hashdance(sk, child, req, own_req);
 201                 goto out;
 202         }
 203
 204         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 205 drop:
 206         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 207                 req->rsk_ops->send_reset(sk, skb);
 208
 209         inet_csk_reqsk_queue_drop(sk, req);
 210 out:
 211         spin_unlock_bh(&dreq->dreq_lock);
 212         return child;
 213 }
 214
 215 EXPORT_SYMBOL_GPL(dccp_check_req);
 216
 217 /*
 218  *  Queue segment on the new socket if the new socket is active,
 219  *  otherwise we just shortcircuit this and continue with
 220  *  the new socket.
 221  */
 222 int dccp_child_process(struct sock *parent, struct sock *child,
 223                        struct sk_buff *skb)
 224 {
 225         int ret = 0;
 226         const int state = child->sk_state;
 227
 228         if (!sock_owned_by_user(child)) {
 229                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 230                                              skb->len);
 231
 232                 /* Wakeup parent, send SIGIO */
 233                 if (state == DCCP_RESPOND && child->sk_state != state)
 234                         parent->sk_data_ready(parent);
 235         } else {
 236                 /* Alas, it is possible again, because we do lookup
 237                  * in main socket hash table and lock on listening
 238                  * socket does not protect us more.
 239                  */
 240                 __sk_add_backlog(child, skb);
 241         }
 242
 243         bh_unlock_sock(child);
 244         sock_put(child);
 245         return ret;
 246 }
 247
 248 EXPORT_SYMBOL_GPL(dccp_child_process);
 249
 250 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 251                          struct request_sock *rsk)
 252 {
 253         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 254 }
 255
 256 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 257
 258 int dccp_reqsk_init(struct request_sock *req,
 259                     struct dccp_sock const *dp, struct sk_buff const *skb)
 260 {
 261         struct dccp_request_sock *dreq = dccp_rsk(req);
 262
 263         spin_lock_init(&dreq->dreq_lock);
 264         inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
 265         inet_rsk(req)->ir_num      = ntohs(dccp_hdr(skb)->dccph_dport);
 266         inet_rsk(req)->acked       = 0;
 267         dreq->dreq_timestamp_echo  = 0;
 268
 269         /* inherit feature negotiation options from listening socket */
 270         return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 271 }
 272
 273 EXPORT_SYMBOL_GPL(dccp_reqsk_init);