1 // SPDX-License-Identifier: GPL-2.0-or-later
5 * An implementation of the DCCP protocol
6 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
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>
17 #include <net/inet_timewait_sock.h>
24 struct inet_timewait_death_row dccp_death_row = {
25 .sysctl_max_tw_buckets = NR_FILE * 2,
26 .hashinfo = &dccp_hashinfo,
29 EXPORT_SYMBOL_GPL(dccp_death_row);
31 void dccp_time_wait(struct sock *sk, int state, int timeo)
33 struct inet_timewait_sock *tw;
35 tw = inet_twsk_alloc(sk, &dccp_death_row, state);
38 const struct inet_connection_sock *icsk = inet_csk(sk);
39 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
40 #if IS_ENABLED(CONFIG_IPV6)
41 if (tw->tw_family == PF_INET6) {
42 tw->tw_v6_daddr = sk->sk_v6_daddr;
43 tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
44 tw->tw_ipv6only = sk->sk_ipv6only;
48 /* Get the TIME_WAIT timeout firing. */
52 if (state == DCCP_TIME_WAIT)
53 timeo = DCCP_TIMEWAIT_LEN;
55 /* tw_timer is pinned, so we need to make sure BH are disabled
56 * in following section, otherwise timer handler could run before
57 * we complete the initialization.
60 inet_twsk_schedule(tw, timeo);
62 * Note that access to tw after this point is illegal.
64 inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
67 /* Sorry, if we're out of memory, just CLOSE this
68 * socket up. We've got bigger problems than
69 * non-graceful socket closings.
71 DCCP_WARN("time wait bucket table overflow\n");
77 struct sock *dccp_create_openreq_child(const struct sock *sk,
78 const struct request_sock *req,
79 const struct sk_buff *skb)
82 * Step 3: Process LISTEN state
84 * (* Generate a new socket and switch to that socket *)
85 * Set S := new socket for this port pair
87 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
90 struct dccp_request_sock *dreq = dccp_rsk(req);
91 struct inet_connection_sock *newicsk = inet_csk(newsk);
92 struct dccp_sock *newdp = dccp_sk(newsk);
94 newdp->dccps_role = DCCP_ROLE_SERVER;
95 newdp->dccps_hc_rx_ackvec = NULL;
96 newdp->dccps_service_list = NULL;
97 newdp->dccps_hc_rx_ccid = NULL;
98 newdp->dccps_hc_tx_ccid = NULL;
99 newdp->dccps_service = dreq->dreq_service;
100 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
101 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
102 newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
104 INIT_LIST_HEAD(&newdp->dccps_featneg);
106 * Step 3: Process LISTEN state
108 * Choose S.ISS (initial seqno) or set from Init Cookies
109 * Initialize S.GAR := S.ISS
110 * Set S.ISR, S.GSR from packet (or Init Cookies)
112 * Setting AWL/AWH and SWL/SWH happens as part of the feature
113 * activation below, as these windows all depend on the local
114 * and remote Sequence Window feature values (7.5.2).
116 newdp->dccps_iss = dreq->dreq_iss;
117 newdp->dccps_gss = dreq->dreq_gss;
118 newdp->dccps_gar = newdp->dccps_iss;
119 newdp->dccps_isr = dreq->dreq_isr;
120 newdp->dccps_gsr = dreq->dreq_gsr;
123 * Activate features: initialise CCIDs, sequence windows etc.
125 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
126 sk_free_unlock_clone(newsk);
129 dccp_init_xmit_timers(newsk);
131 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
136 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
139 * Process an incoming packet for RESPOND sockets represented
140 * as an request_sock.
142 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
143 struct request_sock *req)
145 struct sock *child = NULL;
146 struct dccp_request_sock *dreq = dccp_rsk(req);
149 /* TCP/DCCP listeners became lockless.
150 * DCCP stores complex state in its request_sock, so we need
151 * a protection for them, now this code runs without being protected
152 * by the parent (listener) lock.
154 spin_lock_bh(&dreq->dreq_lock);
156 /* Check for retransmitted REQUEST */
157 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
159 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
160 dccp_pr_debug("Retransmitted REQUEST\n");
161 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
163 * Send another RESPONSE packet
164 * To protect against Request floods, increment retrans
165 * counter (backoff, monitored by dccp_response_timer).
167 inet_rtx_syn_ack(sk, req);
169 /* Network Duplicate, discard packet */
173 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
175 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
176 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
180 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
181 dreq->dreq_iss, dreq->dreq_gss)) {
182 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
183 "dreq_iss=%llu, dreq_gss=%llu\n",
185 DCCP_SKB_CB(skb)->dccpd_ack_seq,
186 (unsigned long long) dreq->dreq_iss,
187 (unsigned long long) dreq->dreq_gss);
191 if (dccp_parse_options(sk, dreq, skb))
194 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
197 child = inet_csk_complete_hashdance(sk, child, req, own_req);
201 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
203 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
204 req->rsk_ops->send_reset(sk, skb);
206 inet_csk_reqsk_queue_drop(sk, req);
208 spin_unlock_bh(&dreq->dreq_lock);
212 EXPORT_SYMBOL_GPL(dccp_check_req);
215 * Queue segment on the new socket if the new socket is active,
216 * otherwise we just shortcircuit this and continue with
219 int dccp_child_process(struct sock *parent, struct sock *child,
224 const int state = child->sk_state;
226 if (!sock_owned_by_user(child)) {
227 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
230 /* Wakeup parent, send SIGIO */
231 if (state == DCCP_RESPOND && child->sk_state != state)
232 parent->sk_data_ready(parent);
234 /* Alas, it is possible again, because we do lookup
235 * in main socket hash table and lock on listening
236 * socket does not protect us more.
238 __sk_add_backlog(child, skb);
241 bh_unlock_sock(child);
246 EXPORT_SYMBOL_GPL(dccp_child_process);
248 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
249 struct request_sock *rsk)
251 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
254 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
256 int dccp_reqsk_init(struct request_sock *req,
257 struct dccp_sock const *dp, struct sk_buff const *skb)
259 struct dccp_request_sock *dreq = dccp_rsk(req);
261 spin_lock_init(&dreq->dreq_lock);
262 inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
263 inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport);
264 inet_rsk(req)->acked = 0;
265 dreq->dreq_timestamp_echo = 0;
267 /* inherit feature negotiation options from listening socket */
268 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
271 EXPORT_SYMBOL_GPL(dccp_reqsk_init);