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