xref: /openbmc/linux/net/dccp/minisocks.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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/config.h>
14 #include <linux/dccp.h>
15 #include <linux/skbuff.h>
16 #include <linux/timer.h>
17 
18 #include <net/sock.h>
19 #include <net/xfrm.h>
20 #include <net/inet_timewait_sock.h>
21 
22 #include "ackvec.h"
23 #include "ccid.h"
24 #include "dccp.h"
25 
26 struct inet_timewait_death_row dccp_death_row = {
27 	.sysctl_max_tw_buckets = NR_FILE * 2,
28 	.period		= DCCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS,
29 	.death_lock	= SPIN_LOCK_UNLOCKED,
30 	.hashinfo	= &dccp_hashinfo,
31 	.tw_timer	= TIMER_INITIALIZER(inet_twdr_hangman, 0,
32 					    (unsigned long)&dccp_death_row),
33 	.twkill_work	= __WORK_INITIALIZER(dccp_death_row.twkill_work,
34 					     inet_twdr_twkill_work,
35 					     &dccp_death_row),
36 /* Short-time timewait calendar */
37 
38 	.twcal_hand	= -1,
39 	.twcal_timer	= TIMER_INITIALIZER(inet_twdr_twcal_tick, 0,
40 					    (unsigned long)&dccp_death_row),
41 };
42 
43 void dccp_time_wait(struct sock *sk, int state, int timeo)
44 {
45 	struct inet_timewait_sock *tw = NULL;
46 
47 	if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
48 		tw = inet_twsk_alloc(sk, state);
49 
50 	if (tw != NULL) {
51 		const struct inet_connection_sock *icsk = inet_csk(sk);
52 		const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
53 
54 		/* Linkage updates. */
55 		__inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
56 
57 		/* Get the TIME_WAIT timeout firing. */
58 		if (timeo < rto)
59 			timeo = rto;
60 
61 		tw->tw_timeout = DCCP_TIMEWAIT_LEN;
62 		if (state == DCCP_TIME_WAIT)
63 			timeo = DCCP_TIMEWAIT_LEN;
64 
65 		inet_twsk_schedule(tw, &dccp_death_row, timeo,
66 				   DCCP_TIMEWAIT_LEN);
67 		inet_twsk_put(tw);
68 	} else {
69 		/* Sorry, if we're out of memory, just CLOSE this
70 		 * socket up.  We've got bigger problems than
71 		 * non-graceful socket closings.
72 		 */
73 		LIMIT_NETDEBUG(KERN_INFO "DCCP: time wait bucket "
74 					 "table overflow\n");
75 	}
76 
77 	dccp_done(sk);
78 }
79 
80 struct sock *dccp_create_openreq_child(struct sock *sk,
81 				       const struct request_sock *req,
82 				       const struct sk_buff *skb)
83 {
84 	/*
85 	 * Step 3: Process LISTEN state
86 	 *
87 	 * // Generate a new socket and switch to that socket
88 	 * Set S := new socket for this port pair
89 	 */
90 	struct sock *newsk = inet_csk_clone(sk, req, GFP_ATOMIC);
91 
92 	if (newsk != NULL) {
93 		const struct dccp_request_sock *dreq = dccp_rsk(req);
94 		struct inet_connection_sock *newicsk = inet_csk(sk);
95 		struct dccp_sock *newdp = dccp_sk(newsk);
96 
97 		newdp->dccps_role	   = DCCP_ROLE_SERVER;
98 		newdp->dccps_hc_rx_ackvec  = NULL;
99 		newdp->dccps_service_list  = NULL;
100 		newdp->dccps_service	   = dreq->dreq_service;
101 		newicsk->icsk_rto	   = DCCP_TIMEOUT_INIT;
102 		do_gettimeofday(&newdp->dccps_epoch);
103 
104 		if (newdp->dccps_options.dccpo_send_ack_vector) {
105 			newdp->dccps_hc_rx_ackvec =
106 				dccp_ackvec_alloc(DCCP_MAX_ACKVEC_LEN,
107 						  GFP_ATOMIC);
108 			/*
109 			 * XXX: We're using the same CCIDs set on the parent,
110 			 * i.e. sk_clone copied the master sock and left the
111 			 * CCID pointers for this child, that is why we do the
112 			 * __ccid_get calls.
113 			 */
114 			if (unlikely(newdp->dccps_hc_rx_ackvec == NULL))
115 				goto out_free;
116 		}
117 
118 		if (unlikely(ccid_hc_rx_init(newdp->dccps_hc_rx_ccid,
119 					     newsk) != 0 ||
120 			     ccid_hc_tx_init(newdp->dccps_hc_tx_ccid,
121 				     	     newsk) != 0)) {
122 			dccp_ackvec_free(newdp->dccps_hc_rx_ackvec);
123 			ccid_hc_rx_exit(newdp->dccps_hc_rx_ccid, newsk);
124 			ccid_hc_tx_exit(newdp->dccps_hc_tx_ccid, newsk);
125 out_free:
126 			/* It is still raw copy of parent, so invalidate
127 			 * destructor and make plain sk_free() */
128 			newsk->sk_destruct = NULL;
129 			sk_free(newsk);
130 			return NULL;
131 		}
132 
133 		__ccid_get(newdp->dccps_hc_rx_ccid);
134 		__ccid_get(newdp->dccps_hc_tx_ccid);
135 
136 		/*
137 		 * Step 3: Process LISTEN state
138 		 *
139 		 *	Choose S.ISS (initial seqno) or set from Init Cookie
140 		 *	Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init
141 		 *	Cookie
142 		 */
143 
144 		/* See dccp_v4_conn_request */
145 		newdp->dccps_options.dccpo_sequence_window = req->rcv_wnd;
146 
147 		newdp->dccps_gar = newdp->dccps_isr = dreq->dreq_isr;
148 		dccp_update_gsr(newsk, dreq->dreq_isr);
149 
150 		newdp->dccps_iss = dreq->dreq_iss;
151 		dccp_update_gss(newsk, dreq->dreq_iss);
152 
153 		/*
154 		 * SWL and AWL are initially adjusted so that they are not less than
155 		 * the initial Sequence Numbers received and sent, respectively:
156 		 *	SWL := max(GSR + 1 - floor(W/4), ISR),
157 		 *	AWL := max(GSS - W' + 1, ISS).
158 		 * These adjustments MUST be applied only at the beginning of the
159 		 * connection.
160 		 */
161 		dccp_set_seqno(&newdp->dccps_swl,
162 			       max48(newdp->dccps_swl, newdp->dccps_isr));
163 		dccp_set_seqno(&newdp->dccps_awl,
164 			       max48(newdp->dccps_awl, newdp->dccps_iss));
165 
166 		dccp_init_xmit_timers(newsk);
167 
168 		DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
169 	}
170 	return newsk;
171 }
172 
173 /*
174  * Process an incoming packet for RESPOND sockets represented
175  * as an request_sock.
176  */
177 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
178 			    struct request_sock *req,
179 			    struct request_sock **prev)
180 {
181 	struct sock *child = NULL;
182 
183 	/* Check for retransmitted REQUEST */
184 	if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
185 		if (after48(DCCP_SKB_CB(skb)->dccpd_seq,
186 			    dccp_rsk(req)->dreq_isr)) {
187 			struct dccp_request_sock *dreq = dccp_rsk(req);
188 
189 			dccp_pr_debug("Retransmitted REQUEST\n");
190 			/* Send another RESPONSE packet */
191 			dccp_set_seqno(&dreq->dreq_iss, dreq->dreq_iss + 1);
192 			dccp_set_seqno(&dreq->dreq_isr,
193 				       DCCP_SKB_CB(skb)->dccpd_seq);
194 			req->rsk_ops->rtx_syn_ack(sk, req, NULL);
195 		}
196 		/* Network Duplicate, discard packet */
197 		return NULL;
198 	}
199 
200 	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
201 
202 	if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
203 	    dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
204 		goto drop;
205 
206 	/* Invalid ACK */
207 	if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dccp_rsk(req)->dreq_iss) {
208 		dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
209 			      "dreq_iss=%llu\n",
210 			      (unsigned long long)
211 			      DCCP_SKB_CB(skb)->dccpd_ack_seq,
212 			      (unsigned long long)
213 			      dccp_rsk(req)->dreq_iss);
214 		goto drop;
215 	}
216 
217 	child = dccp_v4_request_recv_sock(sk, skb, req, NULL);
218 	if (child == NULL)
219 		goto listen_overflow;
220 
221 	/* FIXME: deal with options */
222 
223 	inet_csk_reqsk_queue_unlink(sk, req, prev);
224 	inet_csk_reqsk_queue_removed(sk, req);
225 	inet_csk_reqsk_queue_add(sk, req, child);
226 out:
227 	return child;
228 listen_overflow:
229 	dccp_pr_debug("listen_overflow!\n");
230 	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
231 drop:
232 	if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
233 		req->rsk_ops->send_reset(skb);
234 
235 	inet_csk_reqsk_queue_drop(sk, req, prev);
236 	goto out;
237 }
238 
239 /*
240  *  Queue segment on the new socket if the new socket is active,
241  *  otherwise we just shortcircuit this and continue with
242  *  the new socket.
243  */
244 int dccp_child_process(struct sock *parent, struct sock *child,
245 		       struct sk_buff *skb)
246 {
247 	int ret = 0;
248 	const int state = child->sk_state;
249 
250 	if (!sock_owned_by_user(child)) {
251 		ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
252 					     skb->len);
253 
254 		/* Wakeup parent, send SIGIO */
255 		if (state == DCCP_RESPOND && child->sk_state != state)
256 			parent->sk_data_ready(parent, 0);
257 	} else {
258 		/* Alas, it is possible again, because we do lookup
259 		 * in main socket hash table and lock on listening
260 		 * socket does not protect us more.
261 		 */
262 		sk_add_backlog(child, skb);
263 	}
264 
265 	bh_unlock_sock(child);
266 	sock_put(child);
267 	return ret;
268 }
269