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