1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * net/dccp/minisocks.c
4 *
5 * An implementation of the DCCP protocol
6 * Arnaldo Carvalho de Melo <acme@conectiva.com.br>
7 */
8
9 #include <linux/dccp.h>
10 #include <linux/gfp.h>
11 #include <linux/kernel.h>
12 #include <linux/skbuff.h>
13 #include <linux/timer.h>
14
15 #include <net/sock.h>
16 #include <net/xfrm.h>
17 #include <net/inet_timewait_sock.h>
18
19 #include "ackvec.h"
20 #include "ccid.h"
21 #include "dccp.h"
22 #include "feat.h"
23
24 struct inet_timewait_death_row dccp_death_row = {
25 .sysctl_max_tw_buckets = NR_FILE * 2,
26 .hashinfo = &dccp_hashinfo,
27 };
28
29 EXPORT_SYMBOL_GPL(dccp_death_row);
30
dccp_time_wait(struct sock * sk,int state,int timeo)31 void dccp_time_wait(struct sock *sk, int state, int timeo)
32 {
33 struct inet_timewait_sock *tw;
34
35 tw = inet_twsk_alloc(sk, &dccp_death_row, state);
36
37 if (tw != NULL) {
38 const struct inet_connection_sock *icsk = inet_csk(sk);
39 const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1);
40 #if IS_ENABLED(CONFIG_IPV6)
41 if (tw->tw_family == PF_INET6) {
42 tw->tw_v6_daddr = sk->sk_v6_daddr;
43 tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr;
44 tw->tw_ipv6only = sk->sk_ipv6only;
45 }
46 #endif
47
48 /* Get the TIME_WAIT timeout firing. */
49 if (timeo < rto)
50 timeo = rto;
51
52 if (state == DCCP_TIME_WAIT)
53 timeo = DCCP_TIMEWAIT_LEN;
54
55 /* tw_timer is pinned, so we need to make sure BH are disabled
56 * in following section, otherwise timer handler could run before
57 * we complete the initialization.
58 */
59 local_bh_disable();
60 inet_twsk_schedule(tw, timeo);
61 /* Linkage updates.
62 * Note that access to tw after this point is illegal.
63 */
64 inet_twsk_hashdance(tw, sk, &dccp_hashinfo);
65 local_bh_enable();
66 } else {
67 /* Sorry, if we're out of memory, just CLOSE this
68 * socket up. We've got bigger problems than
69 * non-graceful socket closings.
70 */
71 DCCP_WARN("time wait bucket table overflow\n");
72 }
73
74 dccp_done(sk);
75 }
76
dccp_create_openreq_child(const struct sock * sk,const struct request_sock * req,const struct sk_buff * skb)77 struct sock *dccp_create_openreq_child(const struct sock *sk,
78 const struct request_sock *req,
79 const struct sk_buff *skb)
80 {
81 /*
82 * Step 3: Process LISTEN state
83 *
84 * (* Generate a new socket and switch to that socket *)
85 * Set S := new socket for this port pair
86 */
87 struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
88
89 if (newsk != NULL) {
90 struct dccp_request_sock *dreq = dccp_rsk(req);
91 struct inet_connection_sock *newicsk = inet_csk(newsk);
92 struct dccp_sock *newdp = dccp_sk(newsk);
93
94 newdp->dccps_role = DCCP_ROLE_SERVER;
95 newdp->dccps_hc_rx_ackvec = NULL;
96 newdp->dccps_service_list = NULL;
97 newdp->dccps_service = dreq->dreq_service;
98 newdp->dccps_timestamp_echo = dreq->dreq_timestamp_echo;
99 newdp->dccps_timestamp_time = dreq->dreq_timestamp_time;
100 newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
101
102 INIT_LIST_HEAD(&newdp->dccps_featneg);
103 /*
104 * Step 3: Process LISTEN state
105 *
106 * Choose S.ISS (initial seqno) or set from Init Cookies
107 * Initialize S.GAR := S.ISS
108 * Set S.ISR, S.GSR from packet (or Init Cookies)
109 *
110 * Setting AWL/AWH and SWL/SWH happens as part of the feature
111 * activation below, as these windows all depend on the local
112 * and remote Sequence Window feature values (7.5.2).
113 */
114 newdp->dccps_iss = dreq->dreq_iss;
115 newdp->dccps_gss = dreq->dreq_gss;
116 newdp->dccps_gar = newdp->dccps_iss;
117 newdp->dccps_isr = dreq->dreq_isr;
118 newdp->dccps_gsr = dreq->dreq_gsr;
119
120 /*
121 * Activate features: initialise CCIDs, sequence windows etc.
122 */
123 if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
124 sk_free_unlock_clone(newsk);
125 return NULL;
126 }
127 dccp_init_xmit_timers(newsk);
128
129 __DCCP_INC_STATS(DCCP_MIB_PASSIVEOPENS);
130 }
131 return newsk;
132 }
133
134 EXPORT_SYMBOL_GPL(dccp_create_openreq_child);
135
136 /*
137 * Process an incoming packet for RESPOND sockets represented
138 * as an request_sock.
139 */
dccp_check_req(struct sock * sk,struct sk_buff * skb,struct request_sock * req)140 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
141 struct request_sock *req)
142 {
143 struct sock *child = NULL;
144 struct dccp_request_sock *dreq = dccp_rsk(req);
145 bool own_req;
146
147 /* TCP/DCCP listeners became lockless.
148 * DCCP stores complex state in its request_sock, so we need
149 * a protection for them, now this code runs without being protected
150 * by the parent (listener) lock.
151 */
152 spin_lock_bh(&dreq->dreq_lock);
153
154 /* Check for retransmitted REQUEST */
155 if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
156
157 if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
158 dccp_pr_debug("Retransmitted REQUEST\n");
159 dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
160 /*
161 * Send another RESPONSE packet
162 * To protect against Request floods, increment retrans
163 * counter (backoff, monitored by dccp_response_timer).
164 */
165 inet_rtx_syn_ack(sk, req);
166 }
167 /* Network Duplicate, discard packet */
168 goto out;
169 }
170
171 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
172
173 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
174 dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
175 goto drop;
176
177 /* Invalid ACK */
178 if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
179 dreq->dreq_iss, dreq->dreq_gss)) {
180 dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
181 "dreq_iss=%llu, dreq_gss=%llu\n",
182 (unsigned long long)
183 DCCP_SKB_CB(skb)->dccpd_ack_seq,
184 (unsigned long long) dreq->dreq_iss,
185 (unsigned long long) dreq->dreq_gss);
186 goto drop;
187 }
188
189 if (dccp_parse_options(sk, dreq, skb))
190 goto drop;
191
192 child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL,
193 req, &own_req);
194 if (child) {
195 child = inet_csk_complete_hashdance(sk, child, req, own_req);
196 goto out;
197 }
198
199 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
200 drop:
201 if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
202 req->rsk_ops->send_reset(sk, skb);
203
204 inet_csk_reqsk_queue_drop(sk, req);
205 out:
206 spin_unlock_bh(&dreq->dreq_lock);
207 return child;
208 }
209
210 EXPORT_SYMBOL_GPL(dccp_check_req);
211
212 /*
213 * Queue segment on the new socket if the new socket is active,
214 * otherwise we just shortcircuit this and continue with
215 * the new socket.
216 */
dccp_child_process(struct sock * parent,struct sock * child,struct sk_buff * skb)217 int dccp_child_process(struct sock *parent, struct sock *child,
218 struct sk_buff *skb)
219 __releases(child)
220 {
221 int ret = 0;
222 const int state = child->sk_state;
223
224 if (!sock_owned_by_user(child)) {
225 ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
226 skb->len);
227
228 /* Wakeup parent, send SIGIO */
229 if (state == DCCP_RESPOND && child->sk_state != state)
230 parent->sk_data_ready(parent);
231 } else {
232 /* Alas, it is possible again, because we do lookup
233 * in main socket hash table and lock on listening
234 * socket does not protect us more.
235 */
236 __sk_add_backlog(child, skb);
237 }
238
239 bh_unlock_sock(child);
240 sock_put(child);
241 return ret;
242 }
243
244 EXPORT_SYMBOL_GPL(dccp_child_process);
245
dccp_reqsk_send_ack(const struct sock * sk,struct sk_buff * skb,struct request_sock * rsk)246 void dccp_reqsk_send_ack(const struct sock *sk, struct sk_buff *skb,
247 struct request_sock *rsk)
248 {
249 DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
250 }
251
252 EXPORT_SYMBOL_GPL(dccp_reqsk_send_ack);
253
dccp_reqsk_init(struct request_sock * req,struct dccp_sock const * dp,struct sk_buff const * skb)254 int dccp_reqsk_init(struct request_sock *req,
255 struct dccp_sock const *dp, struct sk_buff const *skb)
256 {
257 struct dccp_request_sock *dreq = dccp_rsk(req);
258
259 spin_lock_init(&dreq->dreq_lock);
260 inet_rsk(req)->ir_rmt_port = dccp_hdr(skb)->dccph_sport;
261 inet_rsk(req)->ir_num = ntohs(dccp_hdr(skb)->dccph_dport);
262 inet_rsk(req)->acked = 0;
263 dreq->dreq_timestamp_echo = 0;
264
265 /* inherit feature negotiation options from listening socket */
266 return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
267 }
268
269 EXPORT_SYMBOL_GPL(dccp_reqsk_init);
270
