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 .period = DCCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS,
31 .death_lock = __SPIN_LOCK_UNLOCKED(dccp_death_row.death_lock),
32 .hashinfo = &dccp_hashinfo,
33 .tw_timer = TIMER_INITIALIZER(inet_twdr_hangman, 0,
34 (unsigned long)&dccp_death_row),
35 .twkill_work = __WORK_INITIALIZER(dccp_death_row.twkill_work,
36 inet_twdr_twkill_work),
37 /* Short-time timewait calendar */
38
39 .twcal_hand = -1,
40 .twcal_timer = TIMER_INITIALIZER(inet_twdr_twcal_tick, 0,
41 (unsigned long)&dccp_death_row),
42 };
43
44 EXPORT_SYMBOL_GPL(dccp_death_row);
45
dccp_time_wait(struct sock * sk,int state,int timeo)46 void dccp_time_wait(struct sock *sk, int state, int timeo)
47 {
48 struct inet_timewait_sock *tw = NULL;
49
50 if (dccp_death_row.tw_count < dccp_death_row.sysctl_max_tw_buckets)
51 tw = inet_twsk_alloc(sk, state);
52
53 if (tw != NULL) {
54 const struct inet_connection_sock *icsk = inet_csk(sk);
55 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
56 #if IS_ENABLED(CONFIG_IPV6)
57 if (tw->tw_family == PF_INET6) {
58 tw->tw_v6_daddr = sk->sk_v6_daddr;
59 tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
60 tw->tw_ipv6only = sk->sk_ipv6only;
61 }
62 #endif
63 /* Linkage updates. */
64 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
65
66 /* Get the TIME_WAIT timeout firing. */
67 if (timeo < rto)
68 timeo = rto;
69
70 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
71 if (state == DCCP_TIME_WAIT)
72 timeo = DCCP_TIMEWAIT_LEN;
73
74 inet_twsk_schedule(tw, &dccp_death_row, timeo,
75 DCCP_TIMEWAIT_LEN);
76 inet_twsk_put(tw);
77 } else {
78 /* Sorry, if we're out of memory, just CLOSE this
79 * socket up. We've got bigger problems than
80 * non-graceful socket closings.
81 */
82 DCCP_WARN("time wait bucket table overflow\n");
83 }
84
85 dccp_done(sk);
86 }
87
dccp_create_openreq_child(struct sock * sk,const struct request_sock * req,const struct sk_buff * skb)88 struct sock *dccp_create_openreq_child(struct sock *sk,
89 const struct request_sock *req,
90 const struct sk_buff *skb)
91 {
92 /*
93 * Step 3: Process LISTEN state
94 *
95 * (* Generate a new socket and switch to that socket *)
96 * Set S := new socket for this port pair
97 */
98 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
99
100 if (newsk != NULL) {
101 struct dccp_request_sock *dreq = dccp_rsk(req);
102 struct inet_connection_sock *newicsk = inet_csk(newsk);
103 struct dccp_sock *newdp = dccp_sk(newsk);
104
105 newdp->dccps_role = DCCP_ROLE_SERVER;
106 newdp->dccps_hc_rx_ackvec = NULL;
107 newdp->dccps_service_list = NULL;
108 newdp->dccps_service = dreq->dreq_service;
109 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
110 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
111 newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
112
113 INIT_LIST_HEAD(&newdp->dccps_featneg);
114 /*
115 * Step 3: Process LISTEN state
116 *
117 * Choose S.ISS (initial seqno) or set from Init Cookies
118 * Initialize S.GAR := S.ISS
119 * Set S.ISR, S.GSR from packet (or Init Cookies)
120 *
121 * Setting AWL/AWH and SWL/SWH happens as part of the feature
122 * activation below, as these windows all depend on the local
123 * and remote Sequence Window feature values (7.5.2).
124 */
125 newdp->dccps_iss = dreq->dreq_iss;
126 newdp->dccps_gss = dreq->dreq_gss;
127 newdp->dccps_gar = newdp->dccps_iss;
128 newdp->dccps_isr = dreq->dreq_isr;
129 newdp->dccps_gsr = dreq->dreq_gsr;
130
131 /*
132 * Activate features: initialise CCIDs, sequence windows etc.
133 */
134 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
135 /* It is still raw copy of parent, so invalidate
136 * destructor and make plain sk_free() */
137 newsk->sk_destruct = NULL;
138 bh_unlock_sock(newsk);
139 sk_free(newsk);
140 return NULL;
141 }
142 dccp_init_xmit_timers(newsk);
143
144 DCCP_INC_STATS_BH(DCCP_MIB_PASSIVEOPENS);
145 }
146 return newsk;
147 }
148
149 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
150
151 /*
152 * Process an incoming packet for RESPOND sockets represented
153 * as an request_sock.
154 */
dccp_check_req(struct sock * sk,struct sk_buff * skb,struct request_sock * req,struct request_sock ** prev)155 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
156 struct request_sock *req,
157 struct request_sock **prev)
158 {
159 struct sock *child = NULL;
160 struct dccp_request_sock *dreq = dccp_rsk(req);
161
162 /* Check for retransmitted REQUEST */
163 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
164
165 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
166 dccp_pr_debug("Retransmitted REQUEST\n");
167 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
168 /*
169 * Send another RESPONSE packet
170 * To protect against Request floods, increment retrans
171 * counter (backoff, monitored by dccp_response_timer).
172 */
173 inet_rtx_syn_ack(sk, req);
174 }
175 /* Network Duplicate, discard packet */
176 return NULL;
177 }
178
179 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
180
181 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
182 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
183 goto drop;
184
185 /* Invalid ACK */
186 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
187 dreq->dreq_iss, dreq->dreq_gss)) {
188 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
189 "dreq_iss=%llu, dreq_gss=%llu\n",
190 (unsigned long long)
191 DCCP_SKB_CB(skb)->dccpd_ack_seq,
192 (unsigned long long) dreq->dreq_iss,
193 (unsigned long long) dreq->dreq_gss);
194 goto drop;
195 }
196
197 if (dccp_parse_options(sk, dreq, skb))
198 goto drop;
199
200 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
201 if (child == NULL)
202 goto listen_overflow;
203
204 inet_csk_reqsk_queue_unlink(sk, req, prev);
205 inet_csk_reqsk_queue_removed(sk, req);
206 inet_csk_reqsk_queue_add(sk, req, child);
207 out:
208 return child;
209 listen_overflow:
210 dccp_pr_debug("listen_overflow!\n");
211 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
212 drop:
213 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
214 req->rsk_ops->send_reset(sk, skb);
215
216 inet_csk_reqsk_queue_drop(sk, req, prev);
217 goto out;
218 }
219
220 EXPORT_SYMBOL_GPL(dccp_check_req);
221
222 /*
223 * Queue segment on the new socket if the new socket is active,
224 * otherwise we just shortcircuit this and continue with
225 * the new socket.
226 */
dccp_child_process(struct sock * parent,struct sock * child,struct sk_buff * skb)227 int dccp_child_process(struct sock *parent, struct sock *child,
228 struct sk_buff *skb)
229 {
230 int ret = 0;
231 const int state = child->sk_state;
232
233 if (!sock_owned_by_user(child)) {
234 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
235 skb->len);
236
237 /* Wakeup parent, send SIGIO */
238 if (state == DCCP_RESPOND && child->sk_state != state)
239 parent->sk_data_ready(parent);
240 } else {
241 /* Alas, it is possible again, because we do lookup
242 * in main socket hash table and lock on listening
243 * socket does not protect us more.
244 */
245 __sk_add_backlog(child, skb);
246 }
247
248 bh_unlock_sock(child);
249 sock_put(child);
250 return ret;
251 }
252
253 EXPORT_SYMBOL_GPL(dccp_child_process);
254
dccp_reqsk_send_ack(struct sock * sk,struct sk_buff * skb,struct request_sock * rsk)255 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
256 struct request_sock *rsk)
257 {
258 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
259 }
260
261 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
262
dccp_reqsk_init(struct request_sock * req,struct dccp_sock const * dp,struct sk_buff const * skb)263 int dccp_reqsk_init(struct request_sock *req,
264 struct dccp_sock const *dp, struct sk_buff const *skb)
265 {
266 struct dccp_request_sock *dreq = dccp_rsk(req);
267
268 inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
269 inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport);
270 inet_rsk(req)->acked = 0;
271 dreq->dreq_timestamp_echo = 0;
272
273 /* inherit feature negotiation options from listening socket */
274 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
275 }
276
277 EXPORT_SYMBOL_GPL(dccp_reqsk_init);
278