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
  19 #include "ackvec.h"
  20 #include "ccid.h"
  21 #include "dccp.h"
  22 #include "feat.h"
  23
  24 struct inet_timewait_death_row dccp_death_row = {
  25         .tw_refcount = REFCOUNT_INIT(1),
  26         .sysctl_max_tw_buckets = NR_FILE * 2,
  27         .hashinfo       = &dccp_hashinfo,
  28 };
  29
  30 EXPORT_SYMBOL_GPL(dccp_death_row);
  31
  32 void dccp_time_wait(struct sock *sk, int state, int timeo)
  33 {
  34         struct inet_timewait_sock *tw;
  35
  36         tw = inet_twsk_alloc(sk, &dccp_death_row, state);
  37
  38         if (tw != NULL) {
  39                 const struct inet_connection_sock *icsk = inet_csk(sk);
  40                 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
  41 #if IS_ENABLED(CONFIG_IPV6)
  42                 if (tw->tw_family == PF_INET6) {
  43                         tw->tw_v6_daddr = sk->sk_v6_daddr;
  44                         tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
  45                         tw->tw_ipv6only = sk->sk_ipv6only;
  46                 }
  47 #endif
  48
  49                 /* Get the TIME_WAIT timeout firing. */
  50                 if (timeo < rto)
  51                         timeo = rto;
  52
  53                 if (state == DCCP_TIME_WAIT)
  54                         timeo = DCCP_TIMEWAIT_LEN;
  55
  56                 /* tw_timer is pinned, so we need to make sure BH are disabled
  57                  * in following section, otherwise timer handler could run before
  58                  * we complete the initialization.
  59                  */
  60                 local_bh_disable();
  61                 inet_twsk_schedule(tw, timeo);
  62                 /* Linkage updates.
  63                  * Note that access to tw after this point is illegal.
  64                  */
  65                 inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
  66                 local_bh_enable();
  67         } else {
  68                 /* Sorry, if we're out of memory, just CLOSE this
  69                  * socket up.  We've got bigger problems than
  70                  * non-graceful socket closings.
  71                  */
  72                 DCCP_WARN("time wait bucket table overflow\n");
  73         }
  74
  75         dccp_done(sk);
  76 }
  77
  78 struct sock *dccp_create_openreq_child(const struct sock *sk,
  79                                        const struct request_sock *req,
  80                                        const struct sk_buff *skb)
  81 {
  82         /*
  83          * Step 3: Process LISTEN state
  84          *
  85          *   (* Generate a new socket and switch to that socket *)
  86          *   Set S := new socket for this port pair
  87          */
  88         struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
  89
  90         if (newsk != NULL) {
  91                 struct dccp_request_sock *dreq = dccp_rsk(req);
  92                 struct inet_connection_sock *newicsk = inet_csk(newsk);
  93                 struct dccp_sock *newdp = dccp_sk(newsk);
  94
  95                 newdp->dccps_role           = DCCP_ROLE_SERVER;
  96                 newdp->dccps_hc_rx_ackvec   = NULL;
  97                 newdp->dccps_service_list   = NULL;
  98                 newdp->dccps_hc_rx_ccid     = NULL;
  99                 newdp->dccps_hc_tx_ccid     = NULL;
 100                 newdp->dccps_service        = dreq->dreq_service;
 101                 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
 102                 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
 103                 newicsk->icsk_rto           = DCCP_TIMEOUT_INIT;
 104
 105                 INIT_LIST_HEAD(&newdp->dccps_featneg);
 106                 /*
 107                  * Step 3: Process LISTEN state
 108                  *
 109                  *    Choose S.ISS (initial seqno) or set from Init Cookies
 110                  *    Initialize S.GAR := S.ISS
 111                  *    Set S.ISR, S.GSR from packet (or Init Cookies)
 112                  *
 113                  *    Setting AWL/AWH and SWL/SWH happens as part of the feature
 114                  *    activation below, as these windows all depend on the local
 115                  *    and remote Sequence Window feature values (7.5.2).
 116                  */
 117                 newdp->dccps_iss = dreq->dreq_iss;
 118                 newdp->dccps_gss = dreq->dreq_gss;
 119                 newdp->dccps_gar = newdp->dccps_iss;
 120                 newdp->dccps_isr = dreq->dreq_isr;
 121                 newdp->dccps_gsr = dreq->dreq_gsr;
 122
 123                 /*
 124                  * Activate features: initialise CCIDs, sequence windows etc.
 125                  */
 126                 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
 127                         sk_free_unlock_clone(newsk);
 128                         return NULL;
 129                 }
 130                 dccp_init_xmit_timers(newsk);
 131
 132                 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
 133         }
 134         return newsk;
 135 }
 136
 137 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
 138
 139 /*
 140  * Process an incoming packet for RESPOND sockets represented
 141  * as an request_sock.
 142  */
 143 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
 144                             struct request_sock *req)
 145 {
 146         struct sock *child = NULL;
 147         struct dccp_request_sock *dreq = dccp_rsk(req);
 148         bool own_req;
 149
 150         /* TCP/DCCP listeners became lockless.
 151          * DCCP stores complex state in its request_sock, so we need
 152          * a protection for them, now this code runs without being protected
 153          * by the parent (listener) lock.
 154          */
 155         spin_lock_bh(&dreq->dreq_lock);
 156
 157         /* Check for retransmitted REQUEST */
 158         if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
 159
 160                 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
 161                         dccp_pr_debug("Retransmitted REQUEST\n");
 162                         dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
 163                         /*
 164                          * Send another RESPONSE packet
 165                          * To protect against Request floods, increment retrans
 166                          * counter (backoff, monitored by dccp_response_timer).
 167                          */
 168                         inet_rtx_syn_ack(sk, req);
 169                 }
 170                 /* Network Duplicate, discard packet */
 171                 goto out;
 172         }
 173
 174         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
 175
 176         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
 177             dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
 178                 goto drop;
 179
 180         /* Invalid ACK */
 181         if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
 182                                 dreq->dreq_iss, dreq->dreq_gss)) {
 183                 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
 184                               "dreq_iss=%llu, dreq_gss=%llu\n",
 185                               (unsigned long long)
 186                               DCCP_SKB_CB(skb)->dccpd_ack_seq,
 187                               (unsigned long long) dreq->dreq_iss,
 188                               (unsigned long long) dreq->dreq_gss);
 189                 goto drop;
 190         }
 191
 192         if (dccp_parse_options(sk, dreq, skb))
 193                  goto drop;
 194
 195         child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
 196                                                          req, &own_req);
 197         if (child) {
 198                 child = inet_csk_complete_hashdance(sk, child, req, own_req);
 199                 goto out;
 200         }
 201
 202         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
 203 drop:
 204         if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
 205                 req->rsk_ops->send_reset(sk, skb);
 206
 207         inet_csk_reqsk_queue_drop(sk, req);
 208 out:
 209         spin_unlock_bh(&dreq->dreq_lock);
 210         return child;
 211 }
 212
 213 EXPORT_SYMBOL_GPL(dccp_check_req);
 214
 215 /*
 216  *  Queue segment on the new socket if the new socket is active,
 217  *  otherwise we just shortcircuit this and continue with
 218  *  the new socket.
 219  */
 220 int dccp_child_process(struct sock *parent, struct sock *child,
 221                        struct sk_buff *skb)
 222         __releases(child)
 223 {
 224         int ret = 0;
 225         const int state = child->sk_state;
 226
 227         if (!sock_owned_by_user(child)) {
 228                 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
 229                                              skb->len);
 230
 231                 /* Wakeup parent, send SIGIO */
 232                 if (state == DCCP_RESPOND && child->sk_state != state)
 233                         parent->sk_data_ready(parent);
 234         } else {
 235                 /* Alas, it is possible again, because we do lookup
 236                  * in main socket hash table and lock on listening
 237                  * socket does not protect us more.
 238                  */
 239                 __sk_add_backlog(child, skb);
 240         }
 241
 242         bh_unlock_sock(child);
 243         sock_put(child);
 244         return ret;
 245 }
 246
 247 EXPORT_SYMBOL_GPL(dccp_child_process);
 248
 249 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
 250                          struct request_sock *rsk)
 251 {
 252         DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
 253 }
 254
 255 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
 256
 257 int dccp_reqsk_init(struct request_sock *req,
 258                     struct dccp_sock const *dp, struct sk_buff const *skb)
 259 {
 260         struct dccp_request_sock *dreq = dccp_rsk(req);
 261
 262         spin_lock_init(&dreq->dreq_lock);
 263         inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
 264         inet_rsk(req)->ir_num      = ntohs(dccp_hdr(skb)->dccph_dport);
 265         inet_rsk(req)->acked       = 0;
 266         dreq->dreq_timestamp_echo  = 0;
 267
 268         /* inherit feature negotiation options from listening socket */
 269         return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
 270 }
 271
 272 EXPORT_SYMBOL_GPL(dccp_reqsk_init);