summaryrefslogtreecommitdiff
path: root/net/dccp/minisocks.c
blob: 64d805b27addea27b3fb0b93fb27514a5ec0ae64 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *  net/dccp/minisocks.c
 *
 *  An implementation of the DCCP protocol
 *  Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 */

#include <linux/dccp.h>
#include <linux/gfp.h>
#include <linux/kernel.h>
#include <linux/skbuff.h>
#include <linux/timer.h>

#include <net/sock.h>
#include <net/xfrm.h>
#include <net/inet_timewait_sock.h>

#include "ackvec.h"
#include "ccid.h"
#include "dccp.h"
#include "feat.h"

struct inet_timewait_death_row dccp_death_row = {
	.tw_refcount = REFCOUNT_INIT(1),
	.sysctl_max_tw_buckets = NR_FILE * 2,
	.hashinfo	= &dccp_hashinfo,
};

EXPORT_SYMBOL_GPL(dccp_death_row);

void dccp_time_wait(struct sock *sk, int state, int timeo)
{
	struct inet_timewait_sock *tw;

	tw = inet_twsk_alloc(sk, &dccp_death_row, state);

	if (tw != NULL) {
		const struct inet_connection_sock *icsk = inet_csk(sk);
		const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
#if IS_ENABLED(CONFIG_IPV6)
		if (tw->tw_family == PF_INET6) {
			tw->tw_v6_daddr = sk->sk_v6_daddr;
			tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
			tw->tw_ipv6only = sk->sk_ipv6only;
		}
#endif

		/* Get the TIME_WAIT timeout firing. */
		if (timeo < rto)
			timeo = rto;

		if (state == DCCP_TIME_WAIT)
			timeo = DCCP_TIMEWAIT_LEN;

		/* tw_timer is pinned, so we need to make sure BH are disabled
		 * in following section, otherwise timer handler could run before
		 * we complete the initialization.
		 */
		local_bh_disable();
		inet_twsk_schedule(tw, timeo);
		/* Linkage updates.
		 * Note that access to tw after this point is illegal.
		 */
		inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
		local_bh_enable();
	} else {
		/* Sorry, if we're out of memory, just CLOSE this
		 * socket up.  We've got bigger problems than
		 * non-graceful socket closings.
		 */
		DCCP_WARN("time wait bucket table overflow\n");
	}

	dccp_done(sk);
}

struct sock *dccp_create_openreq_child(const struct sock *sk,
				       const struct request_sock *req,
				       const struct sk_buff *skb)
{
	/*
	 * Step 3: Process LISTEN state
	 *
	 *   (* Generate a new socket and switch to that socket *)
	 *   Set S := new socket for this port pair
	 */
	struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);

	if (newsk != NULL) {
		struct dccp_request_sock *dreq = dccp_rsk(req);
		struct inet_connection_sock *newicsk = inet_csk(newsk);
		struct dccp_sock *newdp = dccp_sk(newsk);

		newdp->dccps_role	    = DCCP_ROLE_SERVER;
		newdp->dccps_hc_rx_ackvec   = NULL;
		newdp->dccps_service_list   = NULL;
		newdp->dccps_hc_rx_ccid     = NULL;
		newdp->dccps_hc_tx_ccid     = NULL;
		newdp->dccps_service	    = dreq->dreq_service;
		newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
		newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
		newicsk->icsk_rto	    = DCCP_TIMEOUT_INIT;

		INIT_LIST_HEAD(&newdp->dccps_featneg);
		/*
		 * Step 3: Process LISTEN state
		 *
		 *    Choose S.ISS (initial seqno) or set from Init Cookies
		 *    Initialize S.GAR := S.ISS
		 *    Set S.ISR, S.GSR from packet (or Init Cookies)
		 *
		 *    Setting AWL/AWH and SWL/SWH happens as part of the feature
		 *    activation below, as these windows all depend on the local
		 *    and remote Sequence Window feature values (7.5.2).
		 */
		newdp->dccps_iss = dreq->dreq_iss;
		newdp->dccps_gss = dreq->dreq_gss;
		newdp->dccps_gar = newdp->dccps_iss;
		newdp->dccps_isr = dreq->dreq_isr;
		newdp->dccps_gsr = dreq->dreq_gsr;

		/*
		 * Activate features: initialise CCIDs, sequence windows etc.
		 */
		if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
			sk_free_unlock_clone(newsk);
			return NULL;
		}
		dccp_init_xmit_timers(newsk);

		__DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
	}
	return newsk;
}

EXPORT_SYMBOL_GPL(dccp_create_openreq_child);

/*
 * Process an incoming packet for RESPOND sockets represented
 * as an request_sock.
 */
struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
			    struct request_sock *req)
{
	struct sock *child = NULL;
	struct dccp_request_sock *dreq = dccp_rsk(req);
	bool own_req;

	/* TCP/DCCP listeners became lockless.
	 * DCCP stores complex state in its request_sock, so we need
	 * a protection for them, now this code runs without being protected
	 * by the parent (listener) lock.
	 */
	spin_lock_bh(&dreq->dreq_lock);

	/* Check for retransmitted REQUEST */
	if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {

		if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
			dccp_pr_debug("Retransmitted REQUEST\n");
			dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
			/*
			 * Send another RESPONSE packet
			 * To protect against Request floods, increment retrans
			 * counter (backoff, monitored by dccp_response_timer).
			 */
			inet_rtx_syn_ack(sk, req);
		}
		/* Network Duplicate, discard packet */
		goto out;
	}

	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;

	if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
	    dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
		goto drop;

	/* Invalid ACK */
	if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
				dreq->dreq_iss, dreq->dreq_gss)) {
		dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
			      "dreq_iss=%llu, dreq_gss=%llu\n",
			      (unsigned long long)
			      DCCP_SKB_CB(skb)->dccpd_ack_seq,
			      (unsigned long long) dreq->dreq_iss,
			      (unsigned long long) dreq->dreq_gss);
		goto drop;
	}

	if (dccp_parse_options(sk, dreq, skb))
		 goto drop;

	child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
							 req, &own_req);
	if (child) {
		child = inet_csk_complete_hashdance(sk, child, req, own_req);
		goto out;
	}

	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
drop:
	if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
		req->rsk_ops->send_reset(sk, skb);

	inet_csk_reqsk_queue_drop(sk, req);
out:
	spin_unlock_bh(&dreq->dreq_lock);
	return child;
}

EXPORT_SYMBOL_GPL(dccp_check_req);

/*
 *  Queue segment on the new socket if the new socket is active,
 *  otherwise we just shortcircuit this and continue with
 *  the new socket.
 */
int dccp_child_process(struct sock *parent, struct sock *child,
		       struct sk_buff *skb)
	__releases(child)
{
	int ret = 0;
	const int state = child->sk_state;

	if (!sock_owned_by_user(child)) {
		ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
					     skb->len);

		/* Wakeup parent, send SIGIO */
		if (state == DCCP_RESPOND && child->sk_state != state)
			parent->sk_data_ready(parent);
	} else {
		/* Alas, it is possible again, because we do lookup
		 * in main socket hash table and lock on listening
		 * socket does not protect us more.
		 */
		__sk_add_backlog(child, skb);
	}

	bh_unlock_sock(child);
	sock_put(child);
	return ret;
}

EXPORT_SYMBOL_GPL(dccp_child_process);

void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
			 struct request_sock *rsk)
{
	DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
}

EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);

int dccp_reqsk_init(struct request_sock *req,
		    struct dccp_sock const *dp, struct sk_buff const *skb)
{
	struct dccp_request_sock *dreq = dccp_rsk(req);

	spin_lock_init(&dreq->dreq_lock);
	inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
	inet_rsk(req)->ir_num	   = ntohs(dccp_hdr(skb)->dccph_dport);
	inet_rsk(req)->acked	   = 0;
	dreq->dreq_timestamp_echo  = 0;

	/* inherit feature negotiation options from listening socket */
	return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
}

EXPORT_SYMBOL_GPL(dccp_reqsk_init);