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 tw->tw_timeout = DCCP_TIMEWAIT_LEN;
57 if (state == DCCP_TIME_WAIT)
58 timeo = DCCP_TIMEWAIT_LEN;
59
60 /* tw_timer is pinned, so we need to make sure BH are disabled
61 * in following section, otherwise timer handler could run before
62 * we complete the initialization.
63 */
64 local_bh_disable();
65 inet_twsk_schedule(tw, timeo);
66 /* Linkage updates. */
67 __inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
68 inet_twsk_put(tw);
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_service = dreq->dreq_service;
102 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
103 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
104 newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
105
106 INIT_LIST_HEAD(&newdp->dccps_featneg);
107 /*
108 * Step 3: Process LISTEN state
109 *
110 * Choose S.ISS (initial seqno) or set from Init Cookies
111 * Initialize S.GAR := S.ISS
112 * Set S.ISR, S.GSR from packet (or Init Cookies)
113 *
114 * Setting AWL/AWH and SWL/SWH happens as part of the feature
115 * activation below, as these windows all depend on the local
116 * and remote Sequence Window feature values (7.5.2).
117 */
118 newdp->dccps_iss = dreq->dreq_iss;
119 newdp->dccps_gss = dreq->dreq_gss;
120 newdp->dccps_gar = newdp->dccps_iss;
121 newdp->dccps_isr = dreq->dreq_isr;
122 newdp->dccps_gsr = dreq->dreq_gsr;
123
124 /*
125 * Activate features: initialise CCIDs, sequence windows etc.
126 */
127 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
128 /* It is still raw copy of parent, so invalidate
129 * destructor and make plain sk_free() */
130 newsk->sk_destruct = NULL;
131 bh_unlock_sock(newsk);
132 sk_free(newsk);
133 return NULL;
134 }
135 dccp_init_xmit_timers(newsk);
136
137 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
138 }
139 return newsk;
140 }
141
142 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
143
144 /*
145 * Process an incoming packet for RESPOND sockets represented
146 * as an request_sock.
147 */
dccp_check_req(struct sock * sk,struct sk_buff * skb,struct request_sock * req)148 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
149 struct request_sock *req)
150 {
151 struct sock *child = NULL;
152 struct dccp_request_sock *dreq = dccp_rsk(req);
153 bool own_req;
154
155 /* TCP/DCCP listeners became lockless.
156 * DCCP stores complex state in its request_sock, so we need
157 * a protection for them, now this code runs without being protected
158 * by the parent (listener) lock.
159 */
160 spin_lock_bh(&dreq->dreq_lock);
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 goto out;
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 req, &own_req);
202 if (child) {
203 child = inet_csk_complete_hashdance(sk, child, req, own_req);
204 goto out;
205 }
206
207 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
208 drop:
209 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
210 req->rsk_ops->send_reset(sk, skb);
211
212 inet_csk_reqsk_queue_drop(sk, req);
213 out:
214 spin_unlock_bh(&dreq->dreq_lock);
215 return child;
216 }
217
218 EXPORT_SYMBOL_GPL(dccp_check_req);
219
220 /*
221 * Queue segment on the new socket if the new socket is active,
222 * otherwise we just shortcircuit this and continue with
223 * the new socket.
224 */
dccp_child_process(struct sock * parent,struct sock * child,struct sk_buff * skb)225 int dccp_child_process(struct sock *parent, struct sock *child,
226 struct sk_buff *skb)
227 {
228 int ret = 0;
229 const int state = child->sk_state;
230
231 if (!sock_owned_by_user(child)) {
232 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
233 skb->len);
234
235 /* Wakeup parent, send SIGIO */
236 if (state == DCCP_RESPOND && child->sk_state != state)
237 parent->sk_data_ready(parent);
238 } else {
239 /* Alas, it is possible again, because we do lookup
240 * in main socket hash table and lock on listening
241 * socket does not protect us more.
242 */
243 __sk_add_backlog(child, skb);
244 }
245
246 bh_unlock_sock(child);
247 sock_put(child);
248 return ret;
249 }
250
251 EXPORT_SYMBOL_GPL(dccp_child_process);
252
dccp_reqsk_send_ack(const struct sock * sk,struct sk_buff * skb,struct request_sock * rsk)253 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
254 struct request_sock *rsk)
255 {
256 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
257 }
258
259 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
260
dccp_reqsk_init(struct request_sock * req,struct dccp_sock const * dp,struct sk_buff const * skb)261 int dccp_reqsk_init(struct request_sock *req,
262 struct dccp_sock const *dp, struct sk_buff const *skb)
263 {
264 struct dccp_request_sock *dreq = dccp_rsk(req);
265
266 spin_lock_init(&dreq->dreq_lock);
267 inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
268 inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport);
269 inet_rsk(req)->acked = 0;
270 dreq->dreq_timestamp_echo = 0;
271
272 /* inherit feature negotiation options from listening socket */
273 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
274 }
275
276 EXPORT_SYMBOL_GPL(dccp_reqsk_init);
277