net/dccp/minisocks.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *  net/dccp/minisocks.c
   4  *
   5  *  An implementation of the DCCP protocol
   6  *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
   7  */
   8
   9 #include <linux/dccp.h>
  10 #include <linux/gfp.h>
  11 #include <linux/kernel.h>
  12 #include <linux/skbuff.h>
  13 #include <linux/timer.h>
  14
  15 #include <net/sock.h>
  16 #include <net/xfrm.h>
  17 #include <net/inet_timewait_sock.h>
  18 #include <net/rstreason.h>
  19
  20 #include "ackvec.h"
  21 #include "ccid.h"
  22 #include "dccp.h"
  23 #include "feat.h"
  24
  25 struct inet_timewait_death_row dccp_death_row = {
  26         .tw_refcount = REFCOUNT_INIT(1),
  27         .sysctl_max_tw_buckets = NR_FILE * 2,
  28         .hashinfo       = &dccp_hashinfo,
  29 };
  30
  31 EXPORT_SYMBOL_GPL(dccp_death_row);
  32
  33 void dccp_time_wait(struct sock *sk, int state, int timeo)
  34 {
  35         struct inet_timewait_sock *tw;
  36
  37         tw = inet_twsk_alloc(sk, &dccp_death_row, state);
  38
  39         if (tw != NULL) {
  40                 const struct inet_connection_sock *icsk = inet_csk(sk);
  41                 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  42 #if IS_ENABLED(CONFIG_IPV6)
  43                 if (tw->tw_family == PF_INET6) {
  44                         tw->tw_v6_daddr = sk->sk_v6_daddr;
  45                         tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
  46                         tw->tw_ipv6only = sk->sk_ipv6only;
  47                 }
  48 #endif
  49
  50                 /* Get the TIME_WAIT timeout firing. */
  51                 if (timeo < rto)
  52                         timeo = rto;
  53
  54                 if (state == DCCP_TIME_WAIT)
  55                         timeo = DCCP_TIMEWAIT_LEN;
  56
  57                 /* Linkage updates.
  58                  * Note that access to tw after this point is illegal.
  59                  */
  60                 inet_twsk_hashdance_schedule(tw, sk, &dccp_hashinfo, timeo);
  61         } else {
  62                 /* Sorry, if we're out of memory, just CLOSE this
  63                  * socket up.  We've got bigger problems than
  64                  * non-graceful socket closings.
  65                  */
  66                 DCCP_WARN("time wait bucket table overflow\n");
  67         }
  68
  69         dccp_done(sk);
  70 }
  71
  72 struct sock *dccp_create_openreq_child(const struct sock *sk,
  73                                        const struct request_sock *req,
  74                                        const struct sk_buff *skb)
  75 {
  76         /*
  77          * Step 3: Process LISTEN state
  78          *
  79          *   (* Generate a new socket and switch to that socket *)
  80          *   Set S := new socket for this port pair
  81          */
  82         struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
  83
  84         if (newsk != NULL) {
  85                 struct dccp_request_sock *dreq = dccp_rsk(req);
  86                 struct inet_connection_sock *newicsk = inet_csk(newsk);
  87                 struct dccp_sock *newdp = dccp_sk(newsk);
  88
  89                 newdp->dccps_role           = DCCP_ROLE_SERVER;
  90                 newdp->dccps_hc_rx_ackvec   = NULL;
  91                 newdp->dccps_service_list   = NULL;
  92                 newdp->dccps_hc_rx_ccid     = NULL;
  93                 newdp->dccps_hc_tx_ccid     = NULL;
  94                 newdp->dccps_service        = dreq->dreq_service;
  95                 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
  96                 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
  97                 newicsk->icsk_rto           = DCCP_TIMEOUT_INIT;
  98
  99                 INIT_LIST_HEAD(&newdp->dccps_featneg);
 100                 /*
 101                  * Step 3: Process LISTEN state
 102                  *
 103                  *    Choose S.ISS (initial seqno) or set from Init Cookies
 104                  *    Initialize S.GAR := S.ISS
 105                  *    Set S.ISR, S.GSR from packet (or Init Cookies)
 106                  *
 107                  *    Setting AWL/AWH and SWL/SWH happens as part of the feature
 108                  *    activation below, as these windows all depend on the local
 109                  *    and remote Sequence Window feature values (7.5.2).
 110                  */
 111                 newdp->dccps_iss = dreq->dreq_iss;
 112                 newdp->dccps_gss = dreq->dreq_gss;
 113                 newdp->dccps_gar = newdp->dccps_iss;
 114                 newdp->dccps_isr = dreq->dreq_isr;
 115                 newdp->dccps_gsr = dreq->dreq_gsr;
 116
 117                 /*
 118                  * Activate features: initialise CCIDs, sequence windows etc.
 119                  */
 120                 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
 121                         sk_free_unlock_clone(newsk);
 122                         return NULL;
 123                 }
 124                 dccp_init_xmit_timers(newsk);
 125
 126                 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
 127         }
 128         return newsk;
 129 }
 130
 131 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 132
 133 /*
 134  * Process an incoming packet for RESPOND sockets represented
 135  * as an request_sock.
 136  */
 137 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 138                             struct request_sock *req)
 139 {
 140         struct sock *child = NULL;
 141         struct dccp_request_sock *dreq = dccp_rsk(req);
 142         bool own_req;
 143
 144         /* TCP/DCCP listeners became lockless.
 145          * DCCP stores complex state in its request_sock, so we need
 146          * a protection for them, now this code runs without being protected
 147          * by the parent (listener) lock.
 148          */
 149         spin_lock_bh(&dreq->dreq_lock);
 150
 151         /* Check for retransmitted REQUEST */
 152         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 153
 154                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
 155                         dccp_pr_debug("Retransmitted REQUEST\n");
 156                         dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
 157                         /*
 158                          * Send another RESPONSE packet
 159                          * To protect against Request floods, increment retrans
 160                          * counter (backoff, monitored by dccp_response_timer).
 161                          */
 162                         inet_rtx_syn_ack(sk, req);
 163                 }
 164                 /* Network Duplicate, discard packet */
 165                 goto out;
 166         }
 167
 168         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 169
 170         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 171             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 172                 goto drop;
 173
 174         /* Invalid ACK */
 175         if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 176                                 dreq->dreq_iss, dreq->dreq_gss)) {
 177                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 178                               "dreq_iss=%llu, dreq_gss=%llu\n",
 179                               (unsigned long long)
 180                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 181                               (unsigned long long) dreq->dreq_iss,
 182                               (unsigned long long) dreq->dreq_gss);
 183                 goto drop;
 184         }
 185
 186         if (dccp_parse_options(sk, dreq, skb))
 187                  goto drop;
 188
 189         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
 190                                                          req, &own_req);
 191         if (child) {
 192                 child = inet_csk_complete_hashdance(sk, child, req, own_req);
 193                 goto out;
 194         }
 195
 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, SK_RST_REASON_NOT_SPECIFIED);
 200
 201         inet_csk_reqsk_queue_drop(sk, req);
 202 out:
 203         spin_unlock_bh(&dreq->dreq_lock);
 204         return child;
 205 }
 206
 207 EXPORT_SYMBOL_GPL(dccp_check_req);
 208
 209 /*
 210  *  Queue segment on the new socket if the new socket is active,
 211  *  otherwise we just shortcircuit this and continue with
 212  *  the new socket.
 213  */
 214 int dccp_child_process(struct sock *parent, struct sock *child,
 215                        struct sk_buff *skb)
 216         __releases(child)
 217 {
 218         int ret = 0;
 219         const int state = child->sk_state;
 220
 221         if (!sock_owned_by_user(child)) {
 222                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 223                                              skb->len);
 224
 225                 /* Wakeup parent, send SIGIO */
 226                 if (state == DCCP_RESPOND && child->sk_state != state)
 227                         parent->sk_data_ready(parent);
 228         } else {
 229                 /* Alas, it is possible again, because we do lookup
 230                  * in main socket hash table and lock on listening
 231                  * socket does not protect us more.
 232                  */
 233                 __sk_add_backlog(child, skb);
 234         }
 235
 236         bh_unlock_sock(child);
 237         sock_put(child);
 238         return ret;
 239 }
 240
 241 EXPORT_SYMBOL_GPL(dccp_child_process);
 242
 243 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 244                          struct request_sock *rsk)
 245 {
 246         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 247 }
 248
 249 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 250
 251 int dccp_reqsk_init(struct request_sock *req,
 252                     struct dccp_sock const *dp, struct sk_buff const *skb)
 253 {
 254         struct dccp_request_sock *dreq = dccp_rsk(req);
 255
 256         spin_lock_init(&dreq->dreq_lock);
 257         inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
 258         inet_rsk(req)->ir_num      = ntohs(dccp_hdr(skb)->dccph_dport);
 259         inet_rsk(req)->acked       = 0;
 260         dreq->dreq_timestamp_echo  = 0;
 261
 262         /* inherit feature negotiation options from listening socket */
 263         return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 264 }
 265
 266 EXPORT_SYMBOL_GPL(dccp_reqsk_init);