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/kernel.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 #include "feat.h"
26
27 struct inet_timewait_death_row dccp_death_row = {
28 .sysctl_max_tw_buckets = NR_FILE * 2,
29 .period = DCCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS,
30 .death_lock = __SPIN_LOCK_UNLOCKED(dccp_death_row.death_lock),
31 .hashinfo = &dccp_hashinfo,
32 .tw_timer = TIMER_INITIALIZER(inet_twdr_hangman, 0,
33 (unsigned long)&dccp_death_row),
34 .twkill_work = __WORK_INITIALIZER(dccp_death_row.twkill_work,
35 inet_twdr_twkill_work),
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 EXPORT_SYMBOL_GPL(dccp_death_row);
44
dccp_minisock_init(struct dccp_minisock * dmsk)45 void dccp_minisock_init(struct dccp_minisock *dmsk)
46 {
47 dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
48 }
49
dccp_time_wait(struct sock * sk,int state,int timeo)50 void dccp_time_wait(struct sock *sk, int state, int timeo)
51 {
52 struct inet_timewait_sock *tw = NULL;
53
54 if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
55 tw = inet_twsk_alloc(sk, state);
56
57 if (tw != NULL) {
58 const struct inet_connection_sock *icsk = inet_csk(sk);
59 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
60 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
61 if (tw->tw_family == PF_INET6) {
62 const struct ipv6_pinfo *np = inet6_sk(sk);
63 struct inet6_timewait_sock *tw6;
64
65 tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot);
66 tw6 = inet6_twsk((struct sock *)tw);
67 ipv6_addr_copy(&tw6->tw_v6_daddr, &np->daddr);
68 ipv6_addr_copy(&tw6->tw_v6_rcv_saddr, &np->rcv_saddr);
69 tw->tw_ipv6only = np->ipv6only;
70 }
71 #endif
72 /* Linkage updates. */
73 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
74
75 /* Get the TIME_WAIT timeout firing. */
76 if (timeo < rto)
77 timeo = rto;
78
79 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
80 if (state == DCCP_TIME_WAIT)
81 timeo = DCCP_TIMEWAIT_LEN;
82
83 inet_twsk_schedule(tw, &dccp_death_row, timeo,
84 DCCP_TIMEWAIT_LEN);
85 inet_twsk_put(tw);
86 } else {
87 /* Sorry, if we're out of memory, just CLOSE this
88 * socket up. We've got bigger problems than
89 * non-graceful socket closings.
90 */
91 DCCP_WARN("time wait bucket table overflow\n");
92 }
93
94 dccp_done(sk);
95 }
96
dccp_create_openreq_child(struct sock * sk,const struct request_sock * req,const struct sk_buff * skb)97 struct sock *dccp_create_openreq_child(struct sock *sk,
98 const struct request_sock *req,
99 const struct sk_buff *skb)
100 {
101 /*
102 * Step 3: Process LISTEN state
103 *
104 * (* Generate a new socket and switch to that socket *)
105 * Set S := new socket for this port pair
106 */
107 struct sock *newsk = inet_csk_clone(sk, req, GFP_ATOMIC);
108
109 if (newsk != NULL) {
110 struct dccp_request_sock *dreq = dccp_rsk(req);
111 struct inet_connection_sock *newicsk = inet_csk(newsk);
112 struct dccp_sock *newdp = dccp_sk(newsk);
113 struct dccp_minisock *newdmsk = dccp_msk(newsk);
114
115 newdp->dccps_role = DCCP_ROLE_SERVER;
116 newdp->dccps_hc_rx_ackvec = NULL;
117 newdp->dccps_service_list = NULL;
118 newdp->dccps_service = dreq->dreq_service;
119 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
120 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
121 newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
122
123 INIT_LIST_HEAD(&newdp->dccps_featneg);
124 /*
125 * Step 3: Process LISTEN state
126 *
127 * Choose S.ISS (initial seqno) or set from Init Cookies
128 * Initialize S.GAR := S.ISS
129 * Set S.ISR, S.GSR, S.SWL, S.SWH from packet or Init Cookies
130 */
131
132 /* See dccp_v4_conn_request */
133 newdmsk->dccpms_sequence_window = req->rcv_wnd;
134
135 newdp->dccps_gar = newdp->dccps_iss = dreq->dreq_iss;
136 dccp_update_gss(newsk, dreq->dreq_iss);
137
138 newdp->dccps_isr = dreq->dreq_isr;
139 dccp_update_gsr(newsk, dreq->dreq_isr);
140
141 /*
142 * SWL and AWL are initially adjusted so that they are not less than
143 * the initial Sequence Numbers received and sent, respectively:
144 * SWL := max(GSR + 1 - floor(W/4), ISR),
145 * AWL := max(GSS - W' + 1, ISS).
146 * These adjustments MUST be applied only at the beginning of the
147 * connection.
148 */
149 dccp_set_seqno(&newdp->dccps_swl,
150 max48(newdp->dccps_swl, newdp->dccps_isr));
151 dccp_set_seqno(&newdp->dccps_awl,
152 max48(newdp->dccps_awl, newdp->dccps_iss));
153
154 /*
155 * Activate features after initialising the sequence numbers,
156 * since CCID initialisation may depend on GSS, ISR, ISS etc.
157 */
158 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
159 /* It is still raw copy of parent, so invalidate
160 * destructor and make plain sk_free() */
161 newsk->sk_destruct = NULL;
162 sk_free(newsk);
163 return NULL;
164 }
165 dccp_init_xmit_timers(newsk);
166
167 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
168 }
169 return newsk;
170 }
171
172 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
173
174 /*
175 * Process an incoming packet for RESPOND sockets represented
176 * as an request_sock.
177 */
dccp_check_req(struct sock * sk,struct sk_buff * skb,struct request_sock * req,struct request_sock ** prev)178 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
179 struct request_sock *req,
180 struct request_sock **prev)
181 {
182 struct sock *child = NULL;
183 struct dccp_request_sock *dreq = dccp_rsk(req);
184
185 /* Check for retransmitted REQUEST */
186 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
187
188 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_isr)) {
189 dccp_pr_debug("Retransmitted REQUEST\n");
190 dreq->dreq_isr = DCCP_SKB_CB(skb)->dccpd_seq;
191 /*
192 * Send another RESPONSE packet
193 * To protect against Request floods, increment retrans
194 * counter (backoff, monitored by dccp_response_timer).
195 */
196 req->retrans++;
197 req->rsk_ops->rtx_syn_ack(sk, req);
198 }
199 /* Network Duplicate, discard packet */
200 return NULL;
201 }
202
203 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
204
205 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
206 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
207 goto drop;
208
209 /* Invalid ACK */
210 if (DCCP_SKB_CB(skb)->dccpd_ack_seq != dreq->dreq_iss) {
211 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
212 "dreq_iss=%llu\n",
213 (unsigned long long)
214 DCCP_SKB_CB(skb)->dccpd_ack_seq,
215 (unsigned long long) dreq->dreq_iss);
216 goto drop;
217 }
218
219 if (dccp_parse_options(sk, dreq, skb))
220 goto drop;
221
222 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
223 if (child == NULL)
224 goto listen_overflow;
225
226 inet_csk_reqsk_queue_unlink(sk, req, prev);
227 inet_csk_reqsk_queue_removed(sk, req);
228 inet_csk_reqsk_queue_add(sk, req, child);
229 out:
230 return child;
231 listen_overflow:
232 dccp_pr_debug("listen_overflow!\n");
233 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
234 drop:
235 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
236 req->rsk_ops->send_reset(sk, skb);
237
238 inet_csk_reqsk_queue_drop(sk, req, prev);
239 goto out;
240 }
241
242 EXPORT_SYMBOL_GPL(dccp_check_req);
243
244 /*
245 * Queue segment on the new socket if the new socket is active,
246 * otherwise we just shortcircuit this and continue with
247 * the new socket.
248 */
dccp_child_process(struct sock * parent,struct sock * child,struct sk_buff * skb)249 int dccp_child_process(struct sock *parent, struct sock *child,
250 struct sk_buff *skb)
251 {
252 int ret = 0;
253 const int state = child->sk_state;
254
255 if (!sock_owned_by_user(child)) {
256 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
257 skb->len);
258
259 /* Wakeup parent, send SIGIO */
260 if (state == DCCP_RESPOND && child->sk_state != state)
261 parent->sk_data_ready(parent, 0);
262 } else {
263 /* Alas, it is possible again, because we do lookup
264 * in main socket hash table and lock on listening
265 * socket does not protect us more.
266 */
267 sk_add_backlog(child, skb);
268 }
269
270 bh_unlock_sock(child);
271 sock_put(child);
272 return ret;
273 }
274
275 EXPORT_SYMBOL_GPL(dccp_child_process);
276
dccp_reqsk_send_ack(struct sock * sk,struct sk_buff * skb,struct request_sock * rsk)277 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
278 struct request_sock *rsk)
279 {
280 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
281 }
282
283 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
284
dccp_reqsk_init(struct request_sock * req,struct dccp_sock const * dp,struct sk_buff const * skb)285 int dccp_reqsk_init(struct request_sock *req,
286 struct dccp_sock const *dp, struct sk_buff const *skb)
287 {
288 struct dccp_request_sock *dreq = dccp_rsk(req);
289
290 inet_rsk(req)->rmt_port = dccp_hdr(skb)->dccph_sport;
291 inet_rsk(req)->loc_port = dccp_hdr(skb)->dccph_dport;
292 inet_rsk(req)->acked = 0;
293 req->rcv_wnd = sysctl_dccp_feat_sequence_window;
294 dreq->dreq_timestamp_echo = 0;
295
296 /* inherit feature negotiation options from listening socket */
297 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
298 }
299
300 EXPORT_SYMBOL_GPL(dccp_reqsk_init);
301