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 .tw_refcount
= REFCOUNT_INIT(1),
26 .sysctl_max_tw_buckets
= NR_FILE
* 2,
27 .hashinfo
= &dccp_hashinfo
,
30 EXPORT_SYMBOL_GPL(dccp_death_row
);
32 void dccp_time_wait(struct sock
*sk
, int state
, int timeo
)
34 struct inet_timewait_sock
*tw
;
36 tw
= inet_twsk_alloc(sk
, &dccp_death_row
, state
);
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
;
49 /* Get the TIME_WAIT timeout firing. */
53 if (state
== DCCP_TIME_WAIT
)
54 timeo
= DCCP_TIMEWAIT_LEN
;
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.
61 inet_twsk_schedule(tw
, timeo
);
63 * Note that access to tw after this point is illegal.
65 inet_twsk_hashdance(tw
, sk
, &dccp_hashinfo
);
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.
72 DCCP_WARN("time wait bucket table overflow\n");
78 struct sock
*dccp_create_openreq_child(const struct sock
*sk
,
79 const struct request_sock
*req
,
80 const struct sk_buff
*skb
)
83 * Step 3: Process LISTEN state
85 * (* Generate a new socket and switch to that socket *)
86 * Set S := new socket for this port pair
88 struct sock
*newsk
= inet_csk_clone_lock(sk
, req
, GFP_ATOMIC
);
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
);
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
;
105 INIT_LIST_HEAD(&newdp
->dccps_featneg
);
107 * Step 3: Process LISTEN state
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)
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).
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
;
124 * Activate features: initialise CCIDs, sequence windows etc.
126 if (dccp_feat_activate_values(newsk
, &dreq
->dreq_featneg
)) {
127 sk_free_unlock_clone(newsk
);
130 dccp_init_xmit_timers(newsk
);
132 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS
);
137 EXPORT_SYMBOL_GPL(dccp_create_openreq_child
);
140 * Process an incoming packet for RESPOND sockets represented
141 * as an request_sock.
143 struct sock
*dccp_check_req(struct sock
*sk
, struct sk_buff
*skb
,
144 struct request_sock
*req
)
146 struct sock
*child
= NULL
;
147 struct dccp_request_sock
*dreq
= dccp_rsk(req
);
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.
155 spin_lock_bh(&dreq
->dreq_lock
);
157 /* Check for retransmitted REQUEST */
158 if (dccp_hdr(skb
)->dccph_type
== DCCP_PKT_REQUEST
) {
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
;
164 * Send another RESPONSE packet
165 * To protect against Request floods, increment retrans
166 * counter (backoff, monitored by dccp_response_timer).
168 inet_rtx_syn_ack(sk
, req
);
170 /* Network Duplicate, discard packet */
174 DCCP_SKB_CB(skb
)->dccpd_reset_code
= DCCP_RESET_CODE_PACKET_ERROR
;
176 if (dccp_hdr(skb
)->dccph_type
!= DCCP_PKT_ACK
&&
177 dccp_hdr(skb
)->dccph_type
!= DCCP_PKT_DATAACK
)
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",
186 DCCP_SKB_CB(skb
)->dccpd_ack_seq
,
187 (unsigned long long) dreq
->dreq_iss
,
188 (unsigned long long) dreq
->dreq_gss
);
192 if (dccp_parse_options(sk
, dreq
, skb
))
195 child
= inet_csk(sk
)->icsk_af_ops
->syn_recv_sock(sk
, skb
, req
, NULL
,
198 child
= inet_csk_complete_hashdance(sk
, child
, req
, own_req
);
202 DCCP_SKB_CB(skb
)->dccpd_reset_code
= DCCP_RESET_CODE_TOO_BUSY
;
204 if (dccp_hdr(skb
)->dccph_type
!= DCCP_PKT_RESET
)
205 req
->rsk_ops
->send_reset(sk
, skb
);
207 inet_csk_reqsk_queue_drop(sk
, req
);
209 spin_unlock_bh(&dreq
->dreq_lock
);
213 EXPORT_SYMBOL_GPL(dccp_check_req
);
216 * Queue segment on the new socket if the new socket is active,
217 * otherwise we just shortcircuit this and continue with
220 int dccp_child_process(struct sock
*parent
, struct sock
*child
,
225 const int state
= child
->sk_state
;
227 if (!sock_owned_by_user(child
)) {
228 ret
= dccp_rcv_state_process(child
, skb
, dccp_hdr(skb
),
231 /* Wakeup parent, send SIGIO */
232 if (state
== DCCP_RESPOND
&& child
->sk_state
!= state
)
233 parent
->sk_data_ready(parent
);
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.
239 __sk_add_backlog(child
, skb
);
242 bh_unlock_sock(child
);
247 EXPORT_SYMBOL_GPL(dccp_child_process
);
249 void dccp_reqsk_send_ack(const struct sock
*sk
, struct sk_buff
*skb
,
250 struct request_sock
*rsk
)
252 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
255 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack
);
257 int dccp_reqsk_init(struct request_sock
*req
,
258 struct dccp_sock
const *dp
, struct sk_buff
const *skb
)
260 struct dccp_request_sock
*dreq
= dccp_rsk(req
);
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;
268 /* inherit feature negotiation options from listening socket */
269 return dccp_feat_clone_list(&dp
->dccps_featneg
, &dreq
->dreq_featneg
);
272 EXPORT_SYMBOL_GPL(dccp_reqsk_init
);