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
28struct inet_timewait_death_row dccp_death_row = {
29	.sysctl_max_tw_buckets = NR_FILE * 2,
30	.period		= DCCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS,
31	.death_lock	= __SPIN_LOCK_UNLOCKED(dccp_death_row.death_lock),
32	.hashinfo	= &dccp_hashinfo,
33	.tw_timer	= TIMER_INITIALIZER(inet_twdr_hangman, 0,
34					    (unsigned long)&dccp_death_row),
35	.twkill_work	= __WORK_INITIALIZER(dccp_death_row.twkill_work,
36					     inet_twdr_twkill_work),
37/* Short-time timewait calendar */
38
39	.twcal_hand	= -1,
40	.twcal_timer	= TIMER_INITIALIZER(inet_twdr_twcal_tick, 0,
41					    (unsigned long)&dccp_death_row),
42};
43
44EXPORT_SYMBOL_GPL(dccp_death_row);
45
46void dccp_time_wait(struct sock *sk, int state, int timeo)
47{
48	struct inet_timewait_sock *tw = NULL;
49
50	if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
51		tw = inet_twsk_alloc(sk, state);
52
53	if (tw != NULL) {
54		const struct inet_connection_sock *icsk = inet_csk(sk);
55		const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
56#if IS_ENABLED(CONFIG_IPV6)
57		if (tw->tw_family == PF_INET6) {
58			tw->tw_v6_daddr = sk->sk_v6_daddr;
59			tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
60			tw->tw_ipv6only = sk->sk_ipv6only;
61		}
62#endif
63		/* Linkage updates. */
64		__inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
65
66		/* Get the TIME_WAIT timeout firing. */
67		if (timeo < rto)
68			timeo = rto;
69
70		tw->tw_timeout = DCCP_TIMEWAIT_LEN;
71		if (state == DCCP_TIME_WAIT)
72			timeo = DCCP_TIMEWAIT_LEN;
73
74		inet_twsk_schedule(tw, &dccp_death_row, timeo,
75				   DCCP_TIMEWAIT_LEN);
76		inet_twsk_put(tw);
77	} else {
78		/* Sorry, if we're out of memory, just CLOSE this
79		 * socket up.  We've got bigger problems than
80		 * non-graceful socket closings.
81		 */
82		DCCP_WARN("time wait bucket table overflow\n");
83	}
84
85	dccp_done(sk);
86}
87
88struct sock *dccp_create_openreq_child(struct sock *sk,
89				       const struct request_sock *req,
90				       const struct sk_buff *skb)
91{
92	/*
93	 * Step 3: Process LISTEN state
94	 *
95	 *   (* Generate a new socket and switch to that socket *)
96	 *   Set S := new socket for this port pair
97	 */
98	struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
99
100	if (newsk != NULL) {
101		struct dccp_request_sock *dreq = dccp_rsk(req);
102		struct inet_connection_sock *newicsk = inet_csk(newsk);
103		struct dccp_sock *newdp = dccp_sk(newsk);
104
105		newdp->dccps_role	    = DCCP_ROLE_SERVER;
106		newdp->dccps_hc_rx_ackvec   = NULL;
107		newdp->dccps_service_list   = NULL;
108		newdp->dccps_service	    = dreq->dreq_service;
109		newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
110		newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
111		newicsk->icsk_rto	    = DCCP_TIMEOUT_INIT;
112
113		INIT_LIST_HEAD(&newdp->dccps_featneg);
114		/*
115		 * Step 3: Process LISTEN state
116		 *
117		 *    Choose S.ISS (initial seqno) or set from Init Cookies
118		 *    Initialize S.GAR := S.ISS
119		 *    Set S.ISR, S.GSR from packet (or Init Cookies)
120		 *
121		 *    Setting AWL/AWH and SWL/SWH happens as part of the feature
122		 *    activation below, as these windows all depend on the local
123		 *    and remote Sequence Window feature values (7.5.2).
124		 */
125		newdp->dccps_iss = dreq->dreq_iss;
126		newdp->dccps_gss = dreq->dreq_gss;
127		newdp->dccps_gar = newdp->dccps_iss;
128		newdp->dccps_isr = dreq->dreq_isr;
129		newdp->dccps_gsr = dreq->dreq_gsr;
130
131		/*
132		 * Activate features: initialise CCIDs, sequence windows etc.
133		 */
134		if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
135			/* It is still raw copy of parent, so invalidate
136			 * destructor and make plain sk_free() */
137			newsk->sk_destruct = NULL;
138			sk_free(newsk);
139			return NULL;
140		}
141		dccp_init_xmit_timers(newsk);
142
143		DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
144	}
145	return newsk;
146}
147
148EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
149
150/*
151 * Process an incoming packet for RESPOND sockets represented
152 * as an request_sock.
153 */
154struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
155			    struct request_sock *req,
156			    struct request_sock **prev)
157{
158	struct sock *child = NULL;
159	struct dccp_request_sock *dreq = dccp_rsk(req);
160
161	/* Check for retransmitted REQUEST */
162	if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
163
164		if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
165			dccp_pr_debug("Retransmitted REQUEST\n");
166			dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
167			/*
168			 * Send another RESPONSE packet
169			 * To protect against Request floods, increment retrans
170			 * counter (backoff, monitored by dccp_response_timer).
171			 */
172			inet_rtx_syn_ack(sk, req);
173		}
174		/* Network Duplicate, discard packet */
175		return NULL;
176	}
177
178	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
179
180	if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
181	    dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
182		goto drop;
183
184	/* Invalid ACK */
185	if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
186				dreq->dreq_iss, dreq->dreq_gss)) {
187		dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
188			      "dreq_iss=%llu, dreq_gss=%llu\n",
189			      (unsigned long long)
190			      DCCP_SKB_CB(skb)->dccpd_ack_seq,
191			      (unsigned long long) dreq->dreq_iss,
192			      (unsigned long long) dreq->dreq_gss);
193		goto drop;
194	}
195
196	if (dccp_parse_options(sk, dreq, skb))
197		 goto drop;
198
199	child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
200	if (child == NULL)
201		goto listen_overflow;
202
203	inet_csk_reqsk_queue_unlink(sk, req, prev);
204	inet_csk_reqsk_queue_removed(sk, req);
205	inet_csk_reqsk_queue_add(sk, req, child);
206out:
207	return child;
208listen_overflow:
209	dccp_pr_debug("listen_overflow!\n");
210	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
211drop:
212	if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
213		req->rsk_ops->send_reset(sk, skb);
214
215	inet_csk_reqsk_queue_drop(sk, req, prev);
216	goto out;
217}
218
219EXPORT_SYMBOL_GPL(dccp_check_req);
220
221/*
222 *  Queue segment on the new socket if the new socket is active,
223 *  otherwise we just shortcircuit this and continue with
224 *  the new socket.
225 */
226int dccp_child_process(struct sock *parent, struct sock *child,
227		       struct sk_buff *skb)
228{
229	int ret = 0;
230	const int state = child->sk_state;
231
232	if (!sock_owned_by_user(child)) {
233		ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
234					     skb->len);
235
236		/* Wakeup parent, send SIGIO */
237		if (state == DCCP_RESPOND && child->sk_state != state)
238			parent->sk_data_ready(parent);
239	} else {
240		/* Alas, it is possible again, because we do lookup
241		 * in main socket hash table and lock on listening
242		 * socket does not protect us more.
243		 */
244		__sk_add_backlog(child, skb);
245	}
246
247	bh_unlock_sock(child);
248	sock_put(child);
249	return ret;
250}
251
252EXPORT_SYMBOL_GPL(dccp_child_process);
253
254void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
255			 struct request_sock *rsk)
256{
257	DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
258}
259
260EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
261
262int dccp_reqsk_init(struct request_sock *req,
263		    struct dccp_sock const *dp, struct sk_buff const *skb)
264{
265	struct dccp_request_sock *dreq = dccp_rsk(req);
266
267	inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
268	inet_rsk(req)->ir_num	   = ntohs(dccp_hdr(skb)->dccph_dport);
269	inet_rsk(req)->acked	   = 0;
270	dreq->dreq_timestamp_echo  = 0;
271
272	/* inherit feature negotiation options from listening socket */
273	return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
274}
275
276EXPORT_SYMBOL_GPL(dccp_reqsk_init);
277