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                         bh_unlock_sock(newsk);
 126                         sk_free(newsk);
 127                         return NULL;
 128                 }
 129                 dccp_init_xmit_timers(newsk);
 130
 131                 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
 132         }
 133         return newsk;
 134 }
 135
 136 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 137
 138 /*
 139  * Process an incoming packet for RESPOND sockets represented
 140  * as an request_sock.
 141  */
 142 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 143                             struct request_sock *req)
 144 {
 145         struct sock *child = NULL;
 146         struct dccp_request_sock *dreq = dccp_rsk(req);
 147         bool own_req;
 148
 149         /* Check for retransmitted REQUEST */
 150         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 151
 152                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
 153                         dccp_pr_debug("Retransmitted REQUEST\n");
 154                         dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
 155                         /*
 156                          * Send another RESPONSE packet
 157                          * To protect against Request floods, increment retrans
 158                          * counter (backoff, monitored by dccp_response_timer).
 159                          */
 160                         inet_rtx_syn_ack(sk, req);
 161                 }
 162                 /* Network Duplicate, discard packet */
 163                 return NULL;
 164         }
 165
 166         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 167
 168         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 169             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 170                 goto drop;
 171
 172         /* Invalid ACK */
 173         if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 174                                 dreq->dreq_iss, dreq->dreq_gss)) {
 175                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 176                               "dreq_iss=%llu, dreq_gss=%llu\n",
 177                               (unsigned long long)
 178                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 179                               (unsigned long long) dreq->dreq_iss,
 180                               (unsigned long long) dreq->dreq_gss);
 181                 goto drop;
 182         }
 183
 184         if (dccp_parse_options(sk, dreq, skb))
 185                  goto drop;
 186
 187         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
 188                                                          req, &own_req);
 189         if (!child)
 190                 goto listen_overflow;
 191
 192         return inet_csk_complete_hashdance(sk, child, req, own_req);
 193
 194 listen_overflow:
 195         dccp_pr_debug("listen_overflow!\n");
 196         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 197 drop:
 198         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 199                 req->rsk_ops->send_reset(sk, skb);
 200
 201         inet_csk_reqsk_queue_drop(sk, req);
 202         return NULL;
 203 }
 204
 205 EXPORT_SYMBOL_GPL(dccp_check_req);
 206
 207 /*
 208  *  Queue segment on the new socket if the new socket is active,
 209  *  otherwise we just shortcircuit this and continue with
 210  *  the new socket.
 211  */
 212 int dccp_child_process(struct sock *parent, struct sock *child,
 213                        struct sk_buff *skb)
 214 {
 215         int ret = 0;
 216         const int state = child->sk_state;
 217
 218         if (!sock_owned_by_user(child)) {
 219                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 220                                              skb->len);
 221
 222                 /* Wakeup parent, send SIGIO */
 223                 if (state == DCCP_RESPOND && child->sk_state != state)
 224                         parent->sk_data_ready(parent);
 225         } else {
 226                 /* Alas, it is possible again, because we do lookup
 227                  * in main socket hash table and lock on listening
 228                  * socket does not protect us more.
 229                  */
 230                 __sk_add_backlog(child, skb);
 231         }
 232
 233         bh_unlock_sock(child);
 234         sock_put(child);
 235         return ret;
 236 }
 237
 238 EXPORT_SYMBOL_GPL(dccp_child_process);
 239
 240 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 241                          struct request_sock *rsk)
 242 {
 243         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 244 }
 245
 246 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 247
 248 int dccp_reqsk_init(struct request_sock *req,
 249                     struct dccp_sock const *dp, struct sk_buff const *skb)
 250 {
 251         struct dccp_request_sock *dreq = dccp_rsk(req);
 252
 253         inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
 254         inet_rsk(req)->ir_num      = ntohs(dccp_hdr(skb)->dccph_dport);
 255         inet_rsk(req)->acked       = 0;
 256         dreq->dreq_timestamp_echo  = 0;
 257
 258         /* inherit feature negotiation options from listening socket */
 259         return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 260 }
 261
 262 EXPORT_SYMBOL_GPL(dccp_reqsk_init);