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
28 struct inet_timewait_death_row dccp_death_row = {
29 .sysctl_max_tw_buckets = NR_FILE * 2,
30 .hashinfo = &dccp_hashinfo,
31 };
32
33 EXPORT_SYMBOL_GPL(dccp_death_row);
34
dccp_time_wait(struct sock * sk,int state,int timeo)35 void 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 if (state == DCCP_TIME_WAIT)
57 timeo = DCCP_TIMEWAIT_LEN;
58
59 /* tw_timer is pinned, so we need to make sure BH are disabled
60 * in following section, otherwise timer handler could run before
61 * we complete the initialization.
62 */
63 local_bh_disable();
64 inet_twsk_schedule(tw, timeo);
65 /* Linkage updates.
66 * Note that access to tw after this point is illegal.
67 */
68 inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
69 local_bh_enable();
70 } else {
71 /* Sorry, if we're out of memory, just CLOSE this
72 * socket up. We've got bigger problems than
73 * non-graceful socket closings.
74 */
75 DCCP_WARN("time wait bucket table overflow\n");
76 }
77
78 dccp_done(sk);
79 }
80
dccp_create_openreq_child(const struct sock * sk,const struct request_sock * req,const struct sk_buff * skb)81 struct sock *dccp_create_openreq_child(const struct sock *sk,
82 const struct request_sock *req,
83 const struct sk_buff *skb)
84 {
85 /*
86 * Step 3: Process LISTEN state
87 *
88 * (* Generate a new socket and switch to that socket *)
89 * Set S := new socket for this port pair
90 */
91 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
92
93 if (newsk != NULL) {
94 struct dccp_request_sock *dreq = dccp_rsk(req);
95 struct inet_connection_sock *newicsk = inet_csk(newsk);
96 struct dccp_sock *newdp = dccp_sk(newsk);
97
98 newdp->dccps_role = DCCP_ROLE_SERVER;
99 newdp->dccps_hc_rx_ackvec = NULL;
100 newdp->dccps_service_list = NULL;
101 newdp->dccps_hc_rx_ccid = NULL;
102 newdp->dccps_hc_tx_ccid = NULL;
103 newdp->dccps_service = dreq->dreq_service;
104 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
105 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
106 newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
107
108 INIT_LIST_HEAD(&newdp->dccps_featneg);
109 /*
110 * Step 3: Process LISTEN state
111 *
112 * Choose S.ISS (initial seqno) or set from Init Cookies
113 * Initialize S.GAR := S.ISS
114 * Set S.ISR, S.GSR from packet (or Init Cookies)
115 *
116 * Setting AWL/AWH and SWL/SWH happens as part of the feature
117 * activation below, as these windows all depend on the local
118 * and remote Sequence Window feature values (7.5.2).
119 */
120 newdp->dccps_iss = dreq->dreq_iss;
121 newdp->dccps_gss = dreq->dreq_gss;
122 newdp->dccps_gar = newdp->dccps_iss;
123 newdp->dccps_isr = dreq->dreq_isr;
124 newdp->dccps_gsr = dreq->dreq_gsr;
125
126 /*
127 * Activate features: initialise CCIDs, sequence windows etc.
128 */
129 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
130 sk_free_unlock_clone(newsk);
131 return NULL;
132 }
133 dccp_init_xmit_timers(newsk);
134
135 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
136 }
137 return newsk;
138 }
139
140 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
141
142 /*
143 * Process an incoming packet for RESPOND sockets represented
144 * as an request_sock.
145 */
dccp_check_req(struct sock * sk,struct sk_buff * skb,struct request_sock * req)146 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
147 struct request_sock *req)
148 {
149 struct sock *child = NULL;
150 struct dccp_request_sock *dreq = dccp_rsk(req);
151 bool own_req;
152
153 /* TCP/DCCP listeners became lockless.
154 * DCCP stores complex state in its request_sock, so we need
155 * a protection for them, now this code runs without being protected
156 * by the parent (listener) lock.
157 */
158 spin_lock_bh(&dreq->dreq_lock);
159
160 /* Check for retransmitted REQUEST */
161 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
162
163 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
164 dccp_pr_debug("Retransmitted REQUEST\n");
165 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
166 /*
167 * Send another RESPONSE packet
168 * To protect against Request floods, increment retrans
169 * counter (backoff, monitored by dccp_response_timer).
170 */
171 inet_rtx_syn_ack(sk, req);
172 }
173 /* Network Duplicate, discard packet */
174 goto out;
175 }
176
177 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
178
179 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
180 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
181 goto drop;
182
183 /* Invalid ACK */
184 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
185 dreq->dreq_iss, dreq->dreq_gss)) {
186 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
187 "dreq_iss=%llu, dreq_gss=%llu\n",
188 (unsigned long long)
189 DCCP_SKB_CB(skb)->dccpd_ack_seq,
190 (unsigned long long) dreq->dreq_iss,
191 (unsigned long long) dreq->dreq_gss);
192 goto drop;
193 }
194
195 if (dccp_parse_options(sk, dreq, skb))
196 goto drop;
197
198 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
199 req, &own_req);
200 if (child) {
201 child = inet_csk_complete_hashdance(sk, child, req, own_req);
202 goto out;
203 }
204
205 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
206 drop:
207 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
208 req->rsk_ops->send_reset(sk, skb);
209
210 inet_csk_reqsk_queue_drop(sk, req);
211 out:
212 spin_unlock_bh(&dreq->dreq_lock);
213 return child;
214 }
215
216 EXPORT_SYMBOL_GPL(dccp_check_req);
217
218 /*
219 * Queue segment on the new socket if the new socket is active,
220 * otherwise we just shortcircuit this and continue with
221 * the new socket.
222 */
dccp_child_process(struct sock * parent,struct sock * child,struct sk_buff * skb)223 int dccp_child_process(struct sock *parent, struct sock *child,
224 struct sk_buff *skb)
225 {
226 int ret = 0;
227 const int state = child->sk_state;
228
229 if (!sock_owned_by_user(child)) {
230 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
231 skb->len);
232
233 /* Wakeup parent, send SIGIO */
234 if (state == DCCP_RESPOND && child->sk_state != state)
235 parent->sk_data_ready(parent);
236 } else {
237 /* Alas, it is possible again, because we do lookup
238 * in main socket hash table and lock on listening
239 * socket does not protect us more.
240 */
241 __sk_add_backlog(child, skb);
242 }
243
244 bh_unlock_sock(child);
245 sock_put(child);
246 return ret;
247 }
248
249 EXPORT_SYMBOL_GPL(dccp_child_process);
250
dccp_reqsk_send_ack(const struct sock * sk,struct sk_buff * skb,struct request_sock * rsk)251 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
252 struct request_sock *rsk)
253 {
254 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
255 }
256
257 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
258
dccp_reqsk_init(struct request_sock * req,struct dccp_sock const * dp,struct sk_buff const * skb)259 int dccp_reqsk_init(struct request_sock *req,
260 struct dccp_sock const *dp, struct sk_buff const *skb)
261 {
262 struct dccp_request_sock *dreq = dccp_rsk(req);
263
264 spin_lock_init(&dreq->dreq_lock);
265 inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
266 inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport);
267 inet_rsk(req)->acked = 0;
268 dreq->dreq_timestamp_echo = 0;
269
270 /* inherit feature negotiation options from listening socket */
271 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
272 }
273
274 EXPORT_SYMBOL_GPL(dccp_reqsk_init);
275