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