Linux Kernel  3.7.1
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minisocks.c
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1 /*
2  * net/dccp/minisocks.c
3  *
4  * An implementation of the DCCP protocol
5  * Arnaldo Carvalho de Melo <[email protected]>
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 
29  .sysctl_max_tw_buckets = NR_FILE * 2,
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,
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 
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  const struct ipv6_pinfo *np = inet6_sk(sk);
59  struct inet6_timewait_sock *tw6;
60 
61  tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot);
62  tw6 = inet6_twsk((struct sock *)tw);
63  tw6->tw_v6_daddr = np->daddr;
64  tw6->tw_v6_rcv_saddr = np->rcv_saddr;
65  tw->tw_ipv6only = np->ipv6only;
66  }
67 #endif
68  /* Linkage updates. */
70 
71  /* Get the TIME_WAIT timeout firing. */
72  if (timeo < rto)
73  timeo = rto;
74 
76  if (state == DCCP_TIME_WAIT)
77  timeo = DCCP_TIMEWAIT_LEN;
78 
79  inet_twsk_schedule(tw, &dccp_death_row, timeo,
81  inet_twsk_put(tw);
82  } else {
83  /* Sorry, if we're out of memory, just CLOSE this
84  * socket up. We've got bigger problems than
85  * non-graceful socket closings.
86  */
87  DCCP_WARN("time wait bucket table overflow\n");
88  }
89 
90  dccp_done(sk);
91 }
92 
94  const struct request_sock *req,
95  const struct sk_buff *skb)
96 {
97  /*
98  * Step 3: Process LISTEN state
99  *
100  * (* Generate a new socket and switch to that socket *)
101  * Set S := new socket for this port pair
102  */
103  struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC);
104 
105  if (newsk != NULL) {
106  struct dccp_request_sock *dreq = dccp_rsk(req);
107  struct inet_connection_sock *newicsk = inet_csk(newsk);
108  struct dccp_sock *newdp = dccp_sk(newsk);
109 
110  newdp->dccps_role = DCCP_ROLE_SERVER;
111  newdp->dccps_hc_rx_ackvec = NULL;
112  newdp->dccps_service_list = NULL;
113  newdp->dccps_service = dreq->dreq_service;
116  newicsk->icsk_rto = DCCP_TIMEOUT_INIT;
117 
118  INIT_LIST_HEAD(&newdp->dccps_featneg);
119  /*
120  * Step 3: Process LISTEN state
121  *
122  * Choose S.ISS (initial seqno) or set from Init Cookies
123  * Initialize S.GAR := S.ISS
124  * Set S.ISR, S.GSR from packet (or Init Cookies)
125  *
126  * Setting AWL/AWH and SWL/SWH happens as part of the feature
127  * activation below, as these windows all depend on the local
128  * and remote Sequence Window feature values (7.5.2).
129  */
130  newdp->dccps_iss = dreq->dreq_iss;
131  newdp->dccps_gss = dreq->dreq_gss;
132  newdp->dccps_gar = newdp->dccps_iss;
133  newdp->dccps_isr = dreq->dreq_isr;
134  newdp->dccps_gsr = dreq->dreq_gsr;
135 
136  /*
137  * Activate features: initialise CCIDs, sequence windows etc.
138  */
139  if (dccp_feat_activate_values(newsk, &dreq->dreq_featneg)) {
140  /* It is still raw copy of parent, so invalidate
141  * destructor and make plain sk_free() */
142  newsk->sk_destruct = NULL;
143  sk_free(newsk);
144  return NULL;
145  }
146  dccp_init_xmit_timers(newsk);
147 
149  }
150  return newsk;
151 }
152 
154 
155 /*
156  * Process an incoming packet for RESPOND sockets represented
157  * as an request_sock.
158  */
159 struct sock *dccp_check_req(struct sock *sk, struct sk_buff *skb,
160  struct request_sock *req,
161  struct request_sock **prev)
162 {
163  struct sock *child = NULL;
164  struct dccp_request_sock *dreq = dccp_rsk(req);
165 
166  /* Check for retransmitted REQUEST */
167  if (dccp_hdr(skb)->dccph_type == DCCP_PKT_REQUEST) {
168 
169  if (after48(DCCP_SKB_CB(skb)->dccpd_seq, dreq->dreq_gsr)) {
170  dccp_pr_debug("Retransmitted REQUEST\n");
171  dreq->dreq_gsr = DCCP_SKB_CB(skb)->dccpd_seq;
172  /*
173  * Send another RESPONSE packet
174  * To protect against Request floods, increment retrans
175  * counter (backoff, monitored by dccp_response_timer).
176  */
177  req->retrans++;
178  req->rsk_ops->rtx_syn_ack(sk, req, NULL);
179  }
180  /* Network Duplicate, discard packet */
181  return NULL;
182  }
183 
184  DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_PACKET_ERROR;
185 
186  if (dccp_hdr(skb)->dccph_type != DCCP_PKT_ACK &&
187  dccp_hdr(skb)->dccph_type != DCCP_PKT_DATAACK)
188  goto drop;
189 
190  /* Invalid ACK */
191  if (!between48(DCCP_SKB_CB(skb)->dccpd_ack_seq,
192  dreq->dreq_iss, dreq->dreq_gss)) {
193  dccp_pr_debug("Invalid ACK number: ack_seq=%llu, "
194  "dreq_iss=%llu, dreq_gss=%llu\n",
195  (unsigned long long)
196  DCCP_SKB_CB(skb)->dccpd_ack_seq,
197  (unsigned long long) dreq->dreq_iss,
198  (unsigned long long) dreq->dreq_gss);
199  goto drop;
200  }
201 
202  if (dccp_parse_options(sk, dreq, skb))
203  goto drop;
204 
205  child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL);
206  if (child == NULL)
207  goto listen_overflow;
208 
209  inet_csk_reqsk_queue_unlink(sk, req, prev);
210  inet_csk_reqsk_queue_removed(sk, req);
211  inet_csk_reqsk_queue_add(sk, req, child);
212 out:
213  return child;
214 listen_overflow:
215  dccp_pr_debug("listen_overflow!\n");
216  DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_TOO_BUSY;
217 drop:
218  if (dccp_hdr(skb)->dccph_type != DCCP_PKT_RESET)
219  req->rsk_ops->send_reset(sk, skb);
220 
221  inet_csk_reqsk_queue_drop(sk, req, prev);
222  goto out;
223 }
224 
226 
227 /*
228  * Queue segment on the new socket if the new socket is active,
229  * otherwise we just shortcircuit this and continue with
230  * the new socket.
231  */
232 int dccp_child_process(struct sock *parent, struct sock *child,
233  struct sk_buff *skb)
234 {
235  int ret = 0;
236  const int state = child->sk_state;
237 
238  if (!sock_owned_by_user(child)) {
239  ret = dccp_rcv_state_process(child, skb, dccp_hdr(skb),
240  skb->len);
241 
242  /* Wakeup parent, send SIGIO */
243  if (state == DCCP_RESPOND && child->sk_state != state)
244  parent->sk_data_ready(parent, 0);
245  } else {
246  /* Alas, it is possible again, because we do lookup
247  * in main socket hash table and lock on listening
248  * socket does not protect us more.
249  */
250  __sk_add_backlog(child, skb);
251  }
252 
253  bh_unlock_sock(child);
254  sock_put(child);
255  return ret;
256 }
257 
259 
260 void dccp_reqsk_send_ack(struct sock *sk, struct sk_buff *skb,
261  struct request_sock *rsk)
262 {
263  DCCP_BUG("DCCP-ACK packets are never sent in LISTEN/RESPOND state");
264 }
265 
267 
269  struct dccp_sock const *dp, struct sk_buff const *skb)
270 {
271  struct dccp_request_sock *dreq = dccp_rsk(req);
272 
273  inet_rsk(req)->rmt_port = dccp_hdr(skb)->dccph_sport;
274  inet_rsk(req)->loc_port = dccp_hdr(skb)->dccph_dport;
275  inet_rsk(req)->acked = 0;
276  dreq->dreq_timestamp_echo = 0;
277 
278  /* inherit feature negotiation options from listening socket */
279  return dccp_feat_clone_list(&dp->dccps_featneg, &dreq->dreq_featneg);
280 }
281