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457c8996 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * INET An implementation of the TCP/IP protocol suite for the LINUX | |
4 | * operating system. INET is implemented using the BSD Socket | |
5 | * interface as the means of communication with the user level. | |
6 | * | |
7 | * Implementation of the Transmission Control Protocol(TCP). | |
8 | * | |
02c30a84 | 9 | * Authors: Ross Biro |
1da177e4 LT |
10 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
11 | * Mark Evans, <evansmp@uhura.aston.ac.uk> | |
12 | * Corey Minyard <wf-rch!minyard@relay.EU.net> | |
13 | * Florian La Roche, <flla@stud.uni-sb.de> | |
14 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> | |
15 | * Linus Torvalds, <torvalds@cs.helsinki.fi> | |
16 | * Alan Cox, <gw4pts@gw4pts.ampr.org> | |
17 | * Matthew Dillon, <dillon@apollo.west.oic.com> | |
18 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> | |
19 | * Jorge Cwik, <jorge@laser.satlink.net> | |
20 | */ | |
21 | ||
1da177e4 | 22 | #include <net/tcp.h> |
1da177e4 | 23 | #include <net/xfrm.h> |
e5907459 | 24 | #include <net/busy_poll.h> |
1da177e4 | 25 | |
a2a385d6 | 26 | static bool tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win) |
1da177e4 LT |
27 | { |
28 | if (seq == s_win) | |
a2a385d6 | 29 | return true; |
1da177e4 | 30 | if (after(end_seq, s_win) && before(seq, e_win)) |
a2a385d6 | 31 | return true; |
a02cec21 | 32 | return seq == e_win && seq == end_seq; |
1da177e4 LT |
33 | } |
34 | ||
4fb17a60 NC |
35 | static enum tcp_tw_status |
36 | tcp_timewait_check_oow_rate_limit(struct inet_timewait_sock *tw, | |
37 | const struct sk_buff *skb, int mib_idx) | |
38 | { | |
39 | struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); | |
40 | ||
41 | if (!tcp_oow_rate_limited(twsk_net(tw), skb, mib_idx, | |
42 | &tcptw->tw_last_oow_ack_time)) { | |
43 | /* Send ACK. Note, we do not put the bucket, | |
44 | * it will be released by caller. | |
45 | */ | |
46 | return TCP_TW_ACK; | |
47 | } | |
48 | ||
49 | /* We are rate-limiting, so just release the tw sock and drop skb. */ | |
50 | inet_twsk_put(tw); | |
51 | return TCP_TW_SUCCESS; | |
52 | } | |
53 | ||
64382c71 DS |
54 | static void twsk_rcv_nxt_update(struct tcp_timewait_sock *tcptw, u32 seq) |
55 | { | |
56 | #ifdef CONFIG_TCP_AO | |
57 | struct tcp_ao_info *ao; | |
58 | ||
59 | ao = rcu_dereference(tcptw->ao_info); | |
60 | if (unlikely(ao && seq < tcptw->tw_rcv_nxt)) | |
61 | WRITE_ONCE(ao->rcv_sne, ao->rcv_sne + 1); | |
62 | #endif | |
63 | tcptw->tw_rcv_nxt = seq; | |
64 | } | |
65 | ||
e905a9ed | 66 | /* |
1da177e4 LT |
67 | * * Main purpose of TIME-WAIT state is to close connection gracefully, |
68 | * when one of ends sits in LAST-ACK or CLOSING retransmitting FIN | |
69 | * (and, probably, tail of data) and one or more our ACKs are lost. | |
70 | * * What is TIME-WAIT timeout? It is associated with maximal packet | |
71 | * lifetime in the internet, which results in wrong conclusion, that | |
72 | * it is set to catch "old duplicate segments" wandering out of their path. | |
73 | * It is not quite correct. This timeout is calculated so that it exceeds | |
74 | * maximal retransmission timeout enough to allow to lose one (or more) | |
75 | * segments sent by peer and our ACKs. This time may be calculated from RTO. | |
76 | * * When TIME-WAIT socket receives RST, it means that another end | |
77 | * finally closed and we are allowed to kill TIME-WAIT too. | |
78 | * * Second purpose of TIME-WAIT is catching old duplicate segments. | |
79 | * Well, certainly it is pure paranoia, but if we load TIME-WAIT | |
80 | * with this semantics, we MUST NOT kill TIME-WAIT state with RSTs. | |
81 | * * If we invented some more clever way to catch duplicates | |
82 | * (f.e. based on PAWS), we could truncate TIME-WAIT to several RTOs. | |
83 | * | |
84 | * The algorithm below is based on FORMAL INTERPRETATION of RFCs. | |
85 | * When you compare it to RFCs, please, read section SEGMENT ARRIVES | |
86 | * from the very beginning. | |
87 | * | |
88 | * NOTE. With recycling (and later with fin-wait-2) TW bucket | |
89 | * is _not_ stateless. It means, that strictly speaking we must | |
90 | * spinlock it. I do not want! Well, probability of misbehaviour | |
91 | * is ridiculously low and, seems, we could use some mb() tricks | |
92 | * to avoid misread sequence numbers, states etc. --ANK | |
4308fc58 AC |
93 | * |
94 | * We don't need to initialize tmp_out.sack_ok as we don't use the results | |
1da177e4 LT |
95 | */ |
96 | enum tcp_tw_status | |
8feaf0c0 ACM |
97 | tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, |
98 | const struct tcphdr *th) | |
1da177e4 LT |
99 | { |
100 | struct tcp_options_received tmp_opt; | |
4957faad | 101 | struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); |
a2a385d6 | 102 | bool paws_reject = false; |
1da177e4 | 103 | |
bb5b7c11 | 104 | tmp_opt.saw_tstamp = 0; |
8feaf0c0 | 105 | if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) { |
eed29f17 | 106 | tcp_parse_options(twsk_net(tw), skb, &tmp_opt, 0, NULL); |
1da177e4 LT |
107 | |
108 | if (tmp_opt.saw_tstamp) { | |
eee2faab AK |
109 | if (tmp_opt.rcv_tsecr) |
110 | tmp_opt.rcv_tsecr -= tcptw->tw_ts_offset; | |
8feaf0c0 ACM |
111 | tmp_opt.ts_recent = tcptw->tw_ts_recent; |
112 | tmp_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; | |
c887e6d2 | 113 | paws_reject = tcp_paws_reject(&tmp_opt, th->rst); |
1da177e4 LT |
114 | } |
115 | } | |
116 | ||
117 | if (tw->tw_substate == TCP_FIN_WAIT2) { | |
118 | /* Just repeat all the checks of tcp_rcv_state_process() */ | |
119 | ||
120 | /* Out of window, send ACK */ | |
121 | if (paws_reject || | |
122 | !tcp_in_window(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq, | |
8feaf0c0 ACM |
123 | tcptw->tw_rcv_nxt, |
124 | tcptw->tw_rcv_nxt + tcptw->tw_rcv_wnd)) | |
4fb17a60 NC |
125 | return tcp_timewait_check_oow_rate_limit( |
126 | tw, skb, LINUX_MIB_TCPACKSKIPPEDFINWAIT2); | |
1da177e4 LT |
127 | |
128 | if (th->rst) | |
129 | goto kill; | |
130 | ||
8feaf0c0 | 131 | if (th->syn && !before(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt)) |
271c3b9b | 132 | return TCP_TW_RST; |
1da177e4 LT |
133 | |
134 | /* Dup ACK? */ | |
1ac530b3 WY |
135 | if (!th->ack || |
136 | !after(TCP_SKB_CB(skb)->end_seq, tcptw->tw_rcv_nxt) || | |
1da177e4 | 137 | TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) { |
8feaf0c0 | 138 | inet_twsk_put(tw); |
1da177e4 LT |
139 | return TCP_TW_SUCCESS; |
140 | } | |
141 | ||
142 | /* New data or FIN. If new data arrive after half-duplex close, | |
143 | * reset. | |
144 | */ | |
145 | if (!th->fin || | |
271c3b9b | 146 | TCP_SKB_CB(skb)->end_seq != tcptw->tw_rcv_nxt + 1) |
1da177e4 | 147 | return TCP_TW_RST; |
1da177e4 LT |
148 | |
149 | /* FIN arrived, enter true time-wait state. */ | |
8feaf0c0 | 150 | tw->tw_substate = TCP_TIME_WAIT; |
64382c71 DS |
151 | twsk_rcv_nxt_update(tcptw, TCP_SKB_CB(skb)->end_seq); |
152 | ||
1da177e4 | 153 | if (tmp_opt.saw_tstamp) { |
cca9bab1 | 154 | tcptw->tw_ts_recent_stamp = ktime_get_seconds(); |
8feaf0c0 | 155 | tcptw->tw_ts_recent = tmp_opt.rcv_tsval; |
1da177e4 LT |
156 | } |
157 | ||
d82bae12 | 158 | inet_twsk_reschedule(tw, TCP_TIMEWAIT_LEN); |
1da177e4 LT |
159 | return TCP_TW_ACK; |
160 | } | |
161 | ||
162 | /* | |
163 | * Now real TIME-WAIT state. | |
164 | * | |
165 | * RFC 1122: | |
166 | * "When a connection is [...] on TIME-WAIT state [...] | |
167 | * [a TCP] MAY accept a new SYN from the remote TCP to | |
168 | * reopen the connection directly, if it: | |
e905a9ed | 169 | * |
1da177e4 LT |
170 | * (1) assigns its initial sequence number for the new |
171 | * connection to be larger than the largest sequence | |
172 | * number it used on the previous connection incarnation, | |
173 | * and | |
174 | * | |
e905a9ed | 175 | * (2) returns to TIME-WAIT state if the SYN turns out |
1da177e4 LT |
176 | * to be an old duplicate". |
177 | */ | |
178 | ||
179 | if (!paws_reject && | |
8feaf0c0 | 180 | (TCP_SKB_CB(skb)->seq == tcptw->tw_rcv_nxt && |
1da177e4 LT |
181 | (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq || th->rst))) { |
182 | /* In window segment, it may be only reset or bare ack. */ | |
183 | ||
184 | if (th->rst) { | |
caa20d9a | 185 | /* This is TIME_WAIT assassination, in two flavors. |
1da177e4 LT |
186 | * Oh well... nobody has a sufficient solution to this |
187 | * protocol bug yet. | |
188 | */ | |
0b484c91 | 189 | if (!READ_ONCE(twsk_net(tw)->ipv4.sysctl_tcp_rfc1337)) { |
1da177e4 | 190 | kill: |
dbe7faa4 | 191 | inet_twsk_deschedule_put(tw); |
1da177e4 LT |
192 | return TCP_TW_SUCCESS; |
193 | } | |
63cc357f FW |
194 | } else { |
195 | inet_twsk_reschedule(tw, TCP_TIMEWAIT_LEN); | |
1da177e4 | 196 | } |
1da177e4 LT |
197 | |
198 | if (tmp_opt.saw_tstamp) { | |
8feaf0c0 | 199 | tcptw->tw_ts_recent = tmp_opt.rcv_tsval; |
cca9bab1 | 200 | tcptw->tw_ts_recent_stamp = ktime_get_seconds(); |
1da177e4 LT |
201 | } |
202 | ||
8feaf0c0 | 203 | inet_twsk_put(tw); |
1da177e4 LT |
204 | return TCP_TW_SUCCESS; |
205 | } | |
206 | ||
207 | /* Out of window segment. | |
208 | ||
209 | All the segments are ACKed immediately. | |
210 | ||
211 | The only exception is new SYN. We accept it, if it is | |
212 | not old duplicate and we are not in danger to be killed | |
213 | by delayed old duplicates. RFC check is that it has | |
214 | newer sequence number works at rates <40Mbit/sec. | |
215 | However, if paws works, it is reliable AND even more, | |
216 | we even may relax silly seq space cutoff. | |
217 | ||
218 | RED-PEN: we violate main RFC requirement, if this SYN will appear | |
219 | old duplicate (i.e. we receive RST in reply to SYN-ACK), | |
220 | we must return socket to time-wait state. It is not good, | |
221 | but not fatal yet. | |
222 | */ | |
223 | ||
224 | if (th->syn && !th->rst && !th->ack && !paws_reject && | |
8feaf0c0 ACM |
225 | (after(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt) || |
226 | (tmp_opt.saw_tstamp && | |
227 | (s32)(tcptw->tw_ts_recent - tmp_opt.rcv_tsval) < 0))) { | |
228 | u32 isn = tcptw->tw_snd_nxt + 65535 + 2; | |
1da177e4 LT |
229 | if (isn == 0) |
230 | isn++; | |
04317daf | 231 | TCP_SKB_CB(skb)->tcp_tw_isn = isn; |
1da177e4 LT |
232 | return TCP_TW_SYN; |
233 | } | |
234 | ||
235 | if (paws_reject) | |
02a1d6e7 | 236 | __NET_INC_STATS(twsk_net(tw), LINUX_MIB_PAWSESTABREJECTED); |
1da177e4 | 237 | |
2de979bd | 238 | if (!th->rst) { |
1da177e4 LT |
239 | /* In this case we must reset the TIMEWAIT timer. |
240 | * | |
241 | * If it is ACKless SYN it may be both old duplicate | |
242 | * and new good SYN with random sequence number <rcv_nxt. | |
243 | * Do not reschedule in the last case. | |
244 | */ | |
245 | if (paws_reject || th->ack) | |
ed2e9239 | 246 | inet_twsk_reschedule(tw, TCP_TIMEWAIT_LEN); |
1da177e4 | 247 | |
4fb17a60 NC |
248 | return tcp_timewait_check_oow_rate_limit( |
249 | tw, skb, LINUX_MIB_TCPACKSKIPPEDTIMEWAIT); | |
1da177e4 | 250 | } |
8feaf0c0 | 251 | inet_twsk_put(tw); |
1da177e4 LT |
252 | return TCP_TW_SUCCESS; |
253 | } | |
4bc2f18b | 254 | EXPORT_SYMBOL(tcp_timewait_state_process); |
1da177e4 | 255 | |
c5b8b515 DS |
256 | static void tcp_time_wait_init(struct sock *sk, struct tcp_timewait_sock *tcptw) |
257 | { | |
258 | #ifdef CONFIG_TCP_MD5SIG | |
259 | const struct tcp_sock *tp = tcp_sk(sk); | |
260 | struct tcp_md5sig_key *key; | |
261 | ||
262 | /* | |
263 | * The timewait bucket does not have the key DB from the | |
264 | * sock structure. We just make a quick copy of the | |
265 | * md5 key being used (if indeed we are using one) | |
266 | * so the timewait ack generating code has the key. | |
267 | */ | |
268 | tcptw->tw_md5_key = NULL; | |
269 | if (!static_branch_unlikely(&tcp_md5_needed.key)) | |
270 | return; | |
271 | ||
272 | key = tp->af_specific->md5_lookup(sk, sk); | |
273 | if (key) { | |
274 | tcptw->tw_md5_key = kmemdup(key, sizeof(*key), GFP_ATOMIC); | |
275 | if (!tcptw->tw_md5_key) | |
276 | return; | |
c5b8b515 DS |
277 | if (!static_key_fast_inc_not_disabled(&tcp_md5_needed.key.key)) |
278 | goto out_free; | |
8c73b263 | 279 | tcp_md5_add_sigpool(); |
c5b8b515 DS |
280 | } |
281 | return; | |
282 | out_free: | |
283 | WARN_ON_ONCE(1); | |
284 | kfree(tcptw->tw_md5_key); | |
285 | tcptw->tw_md5_key = NULL; | |
286 | #endif | |
287 | } | |
288 | ||
e905a9ed | 289 | /* |
1da177e4 | 290 | * Move a socket to time-wait or dead fin-wait-2 state. |
e905a9ed | 291 | */ |
1da177e4 LT |
292 | void tcp_time_wait(struct sock *sk, int state, int timeo) |
293 | { | |
8292a17a | 294 | const struct inet_connection_sock *icsk = inet_csk(sk); |
decde258 | 295 | struct tcp_sock *tp = tcp_sk(sk); |
08eaef90 | 296 | struct net *net = sock_net(sk); |
789f558c | 297 | struct inet_timewait_sock *tw; |
1da177e4 | 298 | |
e9bd0cca | 299 | tw = inet_twsk_alloc(sk, &net->ipv4.tcp_death_row, state); |
1da177e4 | 300 | |
00db4124 | 301 | if (tw) { |
8feaf0c0 | 302 | struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); |
463c84b9 | 303 | const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1); |
8feaf0c0 | 304 | |
4bd0623f | 305 | tw->tw_transparent = inet_test_bit(TRANSPARENT, sk); |
00483690 | 306 | tw->tw_mark = sk->sk_mark; |
10bbf165 | 307 | tw->tw_priority = READ_ONCE(sk->sk_priority); |
1da177e4 | 308 | tw->tw_rcv_wscale = tp->rx_opt.rcv_wscale; |
8feaf0c0 ACM |
309 | tcptw->tw_rcv_nxt = tp->rcv_nxt; |
310 | tcptw->tw_snd_nxt = tp->snd_nxt; | |
311 | tcptw->tw_rcv_wnd = tcp_receive_window(tp); | |
312 | tcptw->tw_ts_recent = tp->rx_opt.ts_recent; | |
313 | tcptw->tw_ts_recent_stamp = tp->rx_opt.ts_recent_stamp; | |
ceaa1fef | 314 | tcptw->tw_ts_offset = tp->tsoffset; |
614e8316 | 315 | tw->tw_usec_ts = tp->tcp_usec_ts; |
4fb17a60 | 316 | tcptw->tw_last_oow_ack_time = 0; |
a842fe14 | 317 | tcptw->tw_tx_delay = tp->tcp_tx_delay; |
4fbfde4e | 318 | tw->tw_txhash = sk->sk_txhash; |
dfd56b8b | 319 | #if IS_ENABLED(CONFIG_IPV6) |
1da177e4 LT |
320 | if (tw->tw_family == PF_INET6) { |
321 | struct ipv6_pinfo *np = inet6_sk(sk); | |
322 | ||
efe4208f ED |
323 | tw->tw_v6_daddr = sk->sk_v6_daddr; |
324 | tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr; | |
b903d324 | 325 | tw->tw_tclass = np->tclass; |
21858cd0 | 326 | tw->tw_flowlabel = be32_to_cpu(np->flow_label & IPV6_FLOWLABEL_MASK); |
9fe516ba | 327 | tw->tw_ipv6only = sk->sk_ipv6only; |
c676270b | 328 | } |
1da177e4 | 329 | #endif |
cfb6eeb4 | 330 | |
c5b8b515 | 331 | tcp_time_wait_init(sk, tcptw); |
decde258 | 332 | tcp_ao_time_wait(tcptw, tp); |
cfb6eeb4 | 333 | |
1da177e4 LT |
334 | /* Get the TIME_WAIT timeout firing. */ |
335 | if (timeo < rto) | |
336 | timeo = rto; | |
337 | ||
d82bae12 SHY |
338 | if (state == TCP_TIME_WAIT) |
339 | timeo = TCP_TIMEWAIT_LEN; | |
1da177e4 | 340 | |
cfac7f83 ED |
341 | /* tw_timer is pinned, so we need to make sure BH are disabled |
342 | * in following section, otherwise timer handler could run before | |
343 | * we complete the initialization. | |
344 | */ | |
345 | local_bh_disable(); | |
789f558c | 346 | inet_twsk_schedule(tw, timeo); |
ec94c269 ED |
347 | /* Linkage updates. |
348 | * Note that access to tw after this point is illegal. | |
349 | */ | |
4461568a | 350 | inet_twsk_hashdance(tw, sk, net->ipv4.tcp_death_row.hashinfo); |
cfac7f83 | 351 | local_bh_enable(); |
1da177e4 LT |
352 | } else { |
353 | /* Sorry, if we're out of memory, just CLOSE this | |
354 | * socket up. We've got bigger problems than | |
355 | * non-graceful socket closings. | |
356 | */ | |
08eaef90 | 357 | NET_INC_STATS(net, LINUX_MIB_TCPTIMEWAITOVERFLOW); |
1da177e4 LT |
358 | } |
359 | ||
360 | tcp_update_metrics(sk); | |
361 | tcp_done(sk); | |
362 | } | |
cc35c88a | 363 | EXPORT_SYMBOL(tcp_time_wait); |
1da177e4 | 364 | |
8c73b263 DS |
365 | #ifdef CONFIG_TCP_MD5SIG |
366 | static void tcp_md5_twsk_free_rcu(struct rcu_head *head) | |
367 | { | |
368 | struct tcp_md5sig_key *key; | |
369 | ||
370 | key = container_of(head, struct tcp_md5sig_key, rcu); | |
371 | kfree(key); | |
372 | static_branch_slow_dec_deferred(&tcp_md5_needed); | |
373 | tcp_md5_release_sigpool(); | |
374 | } | |
375 | #endif | |
376 | ||
cfb6eeb4 YH |
377 | void tcp_twsk_destructor(struct sock *sk) |
378 | { | |
b6242b9b | 379 | #ifdef CONFIG_TCP_MD5SIG |
459837b5 | 380 | if (static_branch_unlikely(&tcp_md5_needed.key)) { |
6aedbf98 | 381 | struct tcp_timewait_sock *twsk = tcp_twsk(sk); |
2397849b | 382 | |
8c73b263 DS |
383 | if (twsk->tw_md5_key) |
384 | call_rcu(&twsk->tw_md5_key->rcu, tcp_md5_twsk_free_rcu); | |
6aedbf98 | 385 | } |
cfb6eeb4 | 386 | #endif |
decde258 | 387 | tcp_ao_destroy_sock(sk, true); |
cfb6eeb4 | 388 | } |
cfb6eeb4 YH |
389 | EXPORT_SYMBOL_GPL(tcp_twsk_destructor); |
390 | ||
1eeb5043 | 391 | void tcp_twsk_purge(struct list_head *net_exit_list) |
edc12f03 | 392 | { |
d1e5e640 | 393 | bool purged_once = false; |
edc12f03 KI |
394 | struct net *net; |
395 | ||
396 | list_for_each_entry(net, net_exit_list, exit_list) { | |
d1e5e640 | 397 | if (net->ipv4.tcp_death_row.hashinfo->pernet) { |
740ea3c4 | 398 | /* Even if tw_refcount == 1, we must clean up kernel reqsk */ |
1eeb5043 | 399 | inet_twsk_purge(net->ipv4.tcp_death_row.hashinfo); |
d1e5e640 | 400 | } else if (!purged_once) { |
1eeb5043 | 401 | inet_twsk_purge(&tcp_hashinfo); |
d1e5e640 KI |
402 | purged_once = true; |
403 | } | |
edc12f03 KI |
404 | } |
405 | } | |
406 | EXPORT_SYMBOL_GPL(tcp_twsk_purge); | |
407 | ||
b1964b5f ED |
408 | /* Warning : This function is called without sk_listener being locked. |
409 | * Be sure to read socket fields once, as their value could change under us. | |
410 | */ | |
843f4a55 | 411 | void tcp_openreq_init_rwin(struct request_sock *req, |
b1964b5f ED |
412 | const struct sock *sk_listener, |
413 | const struct dst_entry *dst) | |
843f4a55 YC |
414 | { |
415 | struct inet_request_sock *ireq = inet_rsk(req); | |
b1964b5f | 416 | const struct tcp_sock *tp = tcp_sk(sk_listener); |
b1964b5f | 417 | int full_space = tcp_full_space(sk_listener); |
b1964b5f ED |
418 | u32 window_clamp; |
419 | __u8 rcv_wscale; | |
13d3b1eb | 420 | u32 rcv_wnd; |
3541f9e8 | 421 | int mss; |
843f4a55 | 422 | |
3541f9e8 | 423 | mss = tcp_mss_clamp(tp, dst_metric_advmss(dst)); |
b1964b5f | 424 | window_clamp = READ_ONCE(tp->window_clamp); |
843f4a55 | 425 | /* Set this up on the first call only */ |
ed53d0ab | 426 | req->rsk_window_clamp = window_clamp ? : dst_metric(dst, RTAX_WINDOW); |
843f4a55 YC |
427 | |
428 | /* limit the window selection if the user enforce a smaller rx buffer */ | |
b1964b5f | 429 | if (sk_listener->sk_userlocks & SOCK_RCVBUF_LOCK && |
ed53d0ab ED |
430 | (req->rsk_window_clamp > full_space || req->rsk_window_clamp == 0)) |
431 | req->rsk_window_clamp = full_space; | |
843f4a55 | 432 | |
13d3b1eb LB |
433 | rcv_wnd = tcp_rwnd_init_bpf((struct sock *)req); |
434 | if (rcv_wnd == 0) | |
435 | rcv_wnd = dst_metric(dst, RTAX_INITRWND); | |
436 | else if (full_space < rcv_wnd * mss) | |
437 | full_space = rcv_wnd * mss; | |
438 | ||
843f4a55 | 439 | /* tcp_full_space because it is guaranteed to be the first packet */ |
ceef9ab6 | 440 | tcp_select_initial_window(sk_listener, full_space, |
843f4a55 | 441 | mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), |
ed53d0ab ED |
442 | &req->rsk_rcv_wnd, |
443 | &req->rsk_window_clamp, | |
843f4a55 YC |
444 | ireq->wscale_ok, |
445 | &rcv_wscale, | |
13d3b1eb | 446 | rcv_wnd); |
843f4a55 YC |
447 | ireq->rcv_wscale = rcv_wscale; |
448 | } | |
449 | EXPORT_SYMBOL(tcp_openreq_init_rwin); | |
450 | ||
735d3831 FW |
451 | static void tcp_ecn_openreq_child(struct tcp_sock *tp, |
452 | const struct request_sock *req) | |
bdf1ee5d IJ |
453 | { |
454 | tp->ecn_flags = inet_rsk(req)->ecn_ok ? TCP_ECN_OK : 0; | |
455 | } | |
456 | ||
81164413 DB |
457 | void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst) |
458 | { | |
459 | struct inet_connection_sock *icsk = inet_csk(sk); | |
460 | u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); | |
461 | bool ca_got_dst = false; | |
462 | ||
463 | if (ca_key != TCP_CA_UNSPEC) { | |
464 | const struct tcp_congestion_ops *ca; | |
465 | ||
466 | rcu_read_lock(); | |
467 | ca = tcp_ca_find_key(ca_key); | |
0baf26b0 | 468 | if (likely(ca && bpf_try_module_get(ca, ca->owner))) { |
81164413 DB |
469 | icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); |
470 | icsk->icsk_ca_ops = ca; | |
471 | ca_got_dst = true; | |
472 | } | |
473 | rcu_read_unlock(); | |
474 | } | |
475 | ||
9f950415 NC |
476 | /* If no valid choice made yet, assign current system default ca. */ |
477 | if (!ca_got_dst && | |
478 | (!icsk->icsk_ca_setsockopt || | |
0baf26b0 | 479 | !bpf_try_module_get(icsk->icsk_ca_ops, icsk->icsk_ca_ops->owner))) |
81164413 DB |
480 | tcp_assign_congestion_control(sk); |
481 | ||
482 | tcp_set_ca_state(sk, TCP_CA_Open); | |
483 | } | |
484 | EXPORT_SYMBOL_GPL(tcp_ca_openreq_child); | |
485 | ||
e9d9da91 | 486 | static void smc_check_reset_syn_req(const struct tcp_sock *oldtp, |
60e2a778 UB |
487 | struct request_sock *req, |
488 | struct tcp_sock *newtp) | |
489 | { | |
490 | #if IS_ENABLED(CONFIG_SMC) | |
491 | struct inet_request_sock *ireq; | |
492 | ||
493 | if (static_branch_unlikely(&tcp_have_smc)) { | |
494 | ireq = inet_rsk(req); | |
495 | if (oldtp->syn_smc && !ireq->smc_ok) | |
496 | newtp->syn_smc = 0; | |
497 | } | |
498 | #endif | |
499 | } | |
500 | ||
1da177e4 LT |
501 | /* This is not only more efficient than what we used to do, it eliminates |
502 | * a lot of code duplication between IPv4/IPv6 SYN recv processing. -DaveM | |
503 | * | |
504 | * Actually, we could lots of memory writes here. tp of listening | |
505 | * socket contains all necessary default parameters. | |
506 | */ | |
c28c6f04 ED |
507 | struct sock *tcp_create_openreq_child(const struct sock *sk, |
508 | struct request_sock *req, | |
509 | struct sk_buff *skb) | |
1da177e4 | 510 | { |
e56c57d0 | 511 | struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC); |
242b1bbe ED |
512 | const struct inet_request_sock *ireq = inet_rsk(req); |
513 | struct tcp_request_sock *treq = tcp_rsk(req); | |
514 | struct inet_connection_sock *newicsk; | |
e9d9da91 ED |
515 | const struct tcp_sock *oldtp; |
516 | struct tcp_sock *newtp; | |
dba7d9b8 | 517 | u32 seq; |
06b22ef2 DS |
518 | #ifdef CONFIG_TCP_AO |
519 | struct tcp_ao_key *ao_key; | |
520 | #endif | |
242b1bbe ED |
521 | |
522 | if (!newsk) | |
523 | return NULL; | |
524 | ||
525 | newicsk = inet_csk(newsk); | |
526 | newtp = tcp_sk(newsk); | |
527 | oldtp = tcp_sk(sk); | |
528 | ||
529 | smc_check_reset_syn_req(oldtp, req, newtp); | |
530 | ||
531 | /* Now setup tcp_sock */ | |
532 | newtp->pred_flags = 0; | |
533 | ||
dba7d9b8 ED |
534 | seq = treq->rcv_isn + 1; |
535 | newtp->rcv_wup = seq; | |
7db48e98 | 536 | WRITE_ONCE(newtp->copied_seq, seq); |
dba7d9b8 | 537 | WRITE_ONCE(newtp->rcv_nxt, seq); |
242b1bbe ED |
538 | newtp->segs_in = 1; |
539 | ||
e0d694d6 ED |
540 | seq = treq->snt_isn + 1; |
541 | newtp->snd_sml = newtp->snd_una = seq; | |
542 | WRITE_ONCE(newtp->snd_nxt, seq); | |
543 | newtp->snd_up = seq; | |
242b1bbe ED |
544 | |
545 | INIT_LIST_HEAD(&newtp->tsq_node); | |
546 | INIT_LIST_HEAD(&newtp->tsorted_sent_queue); | |
547 | ||
548 | tcp_init_wl(newtp, treq->rcv_isn); | |
549 | ||
242b1bbe | 550 | minmax_reset(&newtp->rtt_min, tcp_jiffies32, ~0U); |
242b1bbe ED |
551 | newicsk->icsk_ack.lrcvtime = tcp_jiffies32; |
552 | ||
242b1bbe | 553 | newtp->lsndtime = tcp_jiffies32; |
5e526552 | 554 | newsk->sk_txhash = READ_ONCE(treq->txhash); |
242b1bbe ED |
555 | newtp->total_retrans = req->num_retrans; |
556 | ||
242b1bbe | 557 | tcp_init_xmit_timers(newsk); |
0f317464 | 558 | WRITE_ONCE(newtp->write_seq, newtp->pushed_seq = treq->snt_isn + 1); |
242b1bbe | 559 | |
242b1bbe ED |
560 | if (sock_flag(newsk, SOCK_KEEPOPEN)) |
561 | inet_csk_reset_keepalive_timer(newsk, | |
562 | keepalive_time_when(newtp)); | |
563 | ||
564 | newtp->rx_opt.tstamp_ok = ireq->tstamp_ok; | |
565 | newtp->rx_opt.sack_ok = ireq->sack_ok; | |
566 | newtp->window_clamp = req->rsk_window_clamp; | |
567 | newtp->rcv_ssthresh = req->rsk_rcv_wnd; | |
568 | newtp->rcv_wnd = req->rsk_rcv_wnd; | |
569 | newtp->rx_opt.wscale_ok = ireq->wscale_ok; | |
570 | if (newtp->rx_opt.wscale_ok) { | |
571 | newtp->rx_opt.snd_wscale = ireq->snd_wscale; | |
572 | newtp->rx_opt.rcv_wscale = ireq->rcv_wscale; | |
573 | } else { | |
574 | newtp->rx_opt.snd_wscale = newtp->rx_opt.rcv_wscale = 0; | |
575 | newtp->window_clamp = min(newtp->window_clamp, 65535U); | |
576 | } | |
577 | newtp->snd_wnd = ntohs(tcp_hdr(skb)->window) << newtp->rx_opt.snd_wscale; | |
578 | newtp->max_window = newtp->snd_wnd; | |
579 | ||
580 | if (newtp->rx_opt.tstamp_ok) { | |
614e8316 | 581 | newtp->tcp_usec_ts = treq->req_usec_ts; |
eba20811 | 582 | newtp->rx_opt.ts_recent = READ_ONCE(req->ts_recent); |
cca9bab1 | 583 | newtp->rx_opt.ts_recent_stamp = ktime_get_seconds(); |
242b1bbe ED |
584 | newtp->tcp_header_len = sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED; |
585 | } else { | |
614e8316 | 586 | newtp->tcp_usec_ts = 0; |
242b1bbe ED |
587 | newtp->rx_opt.ts_recent_stamp = 0; |
588 | newtp->tcp_header_len = sizeof(struct tcphdr); | |
589 | } | |
336c39a0 | 590 | if (req->num_timeout) { |
3868ab0f | 591 | newtp->total_rto = req->num_timeout; |
614e8316 ED |
592 | newtp->undo_marker = treq->snt_isn; |
593 | if (newtp->tcp_usec_ts) { | |
594 | newtp->retrans_stamp = treq->snt_synack; | |
595 | newtp->total_rto_time = (u32)(tcp_clock_us() - | |
596 | newtp->retrans_stamp) / USEC_PER_MSEC; | |
597 | } else { | |
598 | newtp->retrans_stamp = div_u64(treq->snt_synack, | |
599 | USEC_PER_SEC / TCP_TS_HZ); | |
600 | newtp->total_rto_time = tcp_clock_ms() - | |
601 | newtp->retrans_stamp; | |
602 | } | |
3868ab0f | 603 | newtp->total_rto_recoveries = 1; |
336c39a0 | 604 | } |
242b1bbe | 605 | newtp->tsoffset = treq->ts_off; |
cfb6eeb4 | 606 | #ifdef CONFIG_TCP_MD5SIG |
242b1bbe | 607 | newtp->md5sig_info = NULL; /*XXX*/ |
cfb6eeb4 | 608 | #endif |
06b22ef2 DS |
609 | #ifdef CONFIG_TCP_AO |
610 | newtp->ao_info = NULL; | |
611 | ao_key = treq->af_specific->ao_lookup(sk, req, | |
612 | tcp_rsk(req)->ao_keyid, -1); | |
613 | if (ao_key) | |
da7dfaa6 | 614 | newtp->tcp_header_len += tcp_ao_len_aligned(ao_key); |
06b22ef2 | 615 | #endif |
242b1bbe ED |
616 | if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len) |
617 | newicsk->icsk_ack.last_seg_size = skb->len - newtp->tcp_header_len; | |
618 | newtp->rx_opt.mss_clamp = req->mss; | |
619 | tcp_ecn_openreq_child(newtp, req); | |
620 | newtp->fastopen_req = NULL; | |
d983ea6f | 621 | RCU_INIT_POINTER(newtp->fastopen_rsk, NULL); |
242b1bbe | 622 | |
061ff040 | 623 | newtp->bpf_chg_cc_inprogress = 0; |
e8025155 JS |
624 | tcp_bpf_clone(sk, newsk); |
625 | ||
242b1bbe ED |
626 | __TCP_INC_STATS(sock_net(sk), TCP_MIB_PASSIVEOPENS); |
627 | ||
1da177e4 LT |
628 | return newsk; |
629 | } | |
4bc2f18b | 630 | EXPORT_SYMBOL(tcp_create_openreq_child); |
1da177e4 | 631 | |
e905a9ed | 632 | /* |
8336886f JC |
633 | * Process an incoming packet for SYN_RECV sockets represented as a |
634 | * request_sock. Normally sk is the listener socket but for TFO it | |
635 | * points to the child socket. | |
636 | * | |
637 | * XXX (TFO) - The current impl contains a special check for ack | |
638 | * validation and inside tcp_v4_reqsk_send_ack(). Can we do better? | |
4308fc58 AC |
639 | * |
640 | * We don't need to initialize tmp_opt.sack_ok as we don't use the results | |
580f98cc ED |
641 | * |
642 | * Note: If @fastopen is true, this can be called from process context. | |
643 | * Otherwise, this is from BH context. | |
1da177e4 LT |
644 | */ |
645 | ||
5a5f3a8d | 646 | struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, |
60236fdd | 647 | struct request_sock *req, |
e0f9759f | 648 | bool fastopen, bool *req_stolen) |
1da177e4 | 649 | { |
4957faad | 650 | struct tcp_options_received tmp_opt; |
4957faad | 651 | struct sock *child; |
aa8223c7 | 652 | const struct tcphdr *th = tcp_hdr(skb); |
714e85be | 653 | __be32 flg = tcp_flag_word(th) & (TCP_FLAG_RST|TCP_FLAG_SYN|TCP_FLAG_ACK); |
a2a385d6 | 654 | bool paws_reject = false; |
5e0724d0 | 655 | bool own_req; |
1da177e4 | 656 | |
bb5b7c11 DM |
657 | tmp_opt.saw_tstamp = 0; |
658 | if (th->doff > (sizeof(struct tcphdr)>>2)) { | |
eed29f17 | 659 | tcp_parse_options(sock_net(sk), skb, &tmp_opt, 0, NULL); |
1da177e4 LT |
660 | |
661 | if (tmp_opt.saw_tstamp) { | |
eba20811 | 662 | tmp_opt.ts_recent = READ_ONCE(req->ts_recent); |
95a22cae FW |
663 | if (tmp_opt.rcv_tsecr) |
664 | tmp_opt.rcv_tsecr -= tcp_rsk(req)->ts_off; | |
1da177e4 LT |
665 | /* We do not store true stamp, but it is not required, |
666 | * it can be estimated (approximately) | |
667 | * from another data. | |
668 | */ | |
5903123f | 669 | tmp_opt.ts_recent_stamp = ktime_get_seconds() - reqsk_timeout(req, TCP_RTO_MAX) / HZ; |
c887e6d2 | 670 | paws_reject = tcp_paws_reject(&tmp_opt, th->rst); |
1da177e4 LT |
671 | } |
672 | } | |
673 | ||
674 | /* Check for pure retransmitted SYN. */ | |
2e6599cb | 675 | if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn && |
1da177e4 LT |
676 | flg == TCP_FLAG_SYN && |
677 | !paws_reject) { | |
678 | /* | |
679 | * RFC793 draws (Incorrectly! It was fixed in RFC1122) | |
680 | * this case on figure 6 and figure 8, but formal | |
681 | * protocol description says NOTHING. | |
682 | * To be more exact, it says that we should send ACK, | |
683 | * because this segment (at least, if it has no data) | |
684 | * is out of window. | |
685 | * | |
686 | * CONCLUSION: RFC793 (even with RFC1122) DOES NOT | |
687 | * describe SYN-RECV state. All the description | |
688 | * is wrong, we cannot believe to it and should | |
689 | * rely only on common sense and implementation | |
690 | * experience. | |
691 | * | |
692 | * Enforce "SYN-ACK" according to figure 8, figure 6 | |
693 | * of RFC793, fixed by RFC1122. | |
8336886f JC |
694 | * |
695 | * Note that even if there is new data in the SYN packet | |
696 | * they will be thrown away too. | |
cd75eff6 YC |
697 | * |
698 | * Reset timer after retransmitting SYNACK, similar to | |
699 | * the idea of fast retransmit in recovery. | |
1da177e4 | 700 | */ |
a9b2c06d NC |
701 | if (!tcp_oow_rate_limited(sock_net(sk), skb, |
702 | LINUX_MIB_TCPACKSKIPPEDSYNRECV, | |
703 | &tcp_rsk(req)->last_oow_ack_time) && | |
704 | ||
dd929c1b ED |
705 | !inet_rtx_syn_ack(sk, req)) { |
706 | unsigned long expires = jiffies; | |
707 | ||
5903123f | 708 | expires += reqsk_timeout(req, TCP_RTO_MAX); |
dd929c1b ED |
709 | if (!fastopen) |
710 | mod_timer_pending(&req->rsk_timer, expires); | |
711 | else | |
712 | req->rsk_timer.expires = expires; | |
713 | } | |
1da177e4 LT |
714 | return NULL; |
715 | } | |
716 | ||
717 | /* Further reproduces section "SEGMENT ARRIVES" | |
718 | for state SYN-RECEIVED of RFC793. | |
719 | It is broken, however, it does not work only | |
720 | when SYNs are crossed. | |
721 | ||
722 | You would think that SYN crossing is impossible here, since | |
723 | we should have a SYN_SENT socket (from connect()) on our end, | |
724 | but this is not true if the crossed SYNs were sent to both | |
725 | ends by a malicious third party. We must defend against this, | |
726 | and to do that we first verify the ACK (as per RFC793, page | |
727 | 36) and reset if it is invalid. Is this a true full defense? | |
728 | To convince ourselves, let us consider a way in which the ACK | |
729 | test can still pass in this 'malicious crossed SYNs' case. | |
730 | Malicious sender sends identical SYNs (and thus identical sequence | |
731 | numbers) to both A and B: | |
732 | ||
733 | A: gets SYN, seq=7 | |
734 | B: gets SYN, seq=7 | |
735 | ||
736 | By our good fortune, both A and B select the same initial | |
737 | send sequence number of seven :-) | |
738 | ||
739 | A: sends SYN|ACK, seq=7, ack_seq=8 | |
740 | B: sends SYN|ACK, seq=7, ack_seq=8 | |
741 | ||
742 | So we are now A eating this SYN|ACK, ACK test passes. So | |
743 | does sequence test, SYN is truncated, and thus we consider | |
744 | it a bare ACK. | |
745 | ||
ec0a1966 DM |
746 | If icsk->icsk_accept_queue.rskq_defer_accept, we silently drop this |
747 | bare ACK. Otherwise, we create an established connection. Both | |
748 | ends (listening sockets) accept the new incoming connection and try | |
749 | to talk to each other. 8-) | |
1da177e4 LT |
750 | |
751 | Note: This case is both harmless, and rare. Possibility is about the | |
752 | same as us discovering intelligent life on another plant tomorrow. | |
753 | ||
754 | But generally, we should (RFC lies!) to accept ACK | |
755 | from SYNACK both here and in tcp_rcv_state_process(). | |
756 | tcp_rcv_state_process() does not, hence, we do not too. | |
757 | ||
758 | Note that the case is absolutely generic: | |
759 | we cannot optimize anything here without | |
760 | violating protocol. All the checks must be made | |
761 | before attempt to create socket. | |
762 | */ | |
763 | ||
764 | /* RFC793 page 36: "If the connection is in any non-synchronized state ... | |
765 | * and the incoming segment acknowledges something not yet | |
caa20d9a | 766 | * sent (the segment carries an unacceptable ACK) ... |
1da177e4 LT |
767 | * a reset is sent." |
768 | * | |
8336886f JC |
769 | * Invalid ACK: reset will be sent by listening socket. |
770 | * Note that the ACK validity check for a Fast Open socket is done | |
771 | * elsewhere and is checked directly against the child socket rather | |
772 | * than req because user data may have been sent out. | |
1da177e4 | 773 | */ |
8336886f | 774 | if ((flg & TCP_FLAG_ACK) && !fastopen && |
435cf559 | 775 | (TCP_SKB_CB(skb)->ack_seq != |
1a2c6181 | 776 | tcp_rsk(req)->snt_isn + 1)) |
1da177e4 LT |
777 | return sk; |
778 | ||
779 | /* Also, it would be not so bad idea to check rcv_tsecr, which | |
780 | * is essentially ACK extension and too early or too late values | |
781 | * should cause reset in unsynchronized states. | |
782 | */ | |
783 | ||
784 | /* RFC793: "first check sequence number". */ | |
785 | ||
786 | if (paws_reject || !tcp_in_window(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq, | |
ed53d0ab | 787 | tcp_rsk(req)->rcv_nxt, tcp_rsk(req)->rcv_nxt + req->rsk_rcv_wnd)) { |
1da177e4 | 788 | /* Out of window: send ACK and drop. */ |
4ce7e93c ED |
789 | if (!(flg & TCP_FLAG_RST) && |
790 | !tcp_oow_rate_limited(sock_net(sk), skb, | |
791 | LINUX_MIB_TCPACKSKIPPEDSYNRECV, | |
792 | &tcp_rsk(req)->last_oow_ack_time)) | |
6edafaaf | 793 | req->rsk_ops->send_ack(sk, skb, req); |
1da177e4 | 794 | if (paws_reject) |
580f98cc | 795 | NET_INC_STATS(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED); |
1da177e4 LT |
796 | return NULL; |
797 | } | |
798 | ||
799 | /* In sequence, PAWS is OK. */ | |
800 | ||
eba20811 ED |
801 | /* TODO: We probably should defer ts_recent change once |
802 | * we take ownership of @req. | |
803 | */ | |
8336886f | 804 | if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_nxt)) |
eba20811 | 805 | WRITE_ONCE(req->ts_recent, tmp_opt.rcv_tsval); |
1da177e4 | 806 | |
2aaab9a0 AL |
807 | if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) { |
808 | /* Truncate SYN, it is out of window starting | |
809 | at tcp_rsk(req)->rcv_isn + 1. */ | |
810 | flg &= ~TCP_FLAG_SYN; | |
811 | } | |
1da177e4 | 812 | |
2aaab9a0 AL |
813 | /* RFC793: "second check the RST bit" and |
814 | * "fourth, check the SYN bit" | |
815 | */ | |
816 | if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN)) { | |
580f98cc | 817 | TCP_INC_STATS(sock_net(sk), TCP_MIB_ATTEMPTFAILS); |
2aaab9a0 AL |
818 | goto embryonic_reset; |
819 | } | |
1da177e4 | 820 | |
2aaab9a0 AL |
821 | /* ACK sequence verified above, just make sure ACK is |
822 | * set. If ACK not set, just silently drop the packet. | |
8336886f JC |
823 | * |
824 | * XXX (TFO) - if we ever allow "data after SYN", the | |
825 | * following check needs to be removed. | |
2aaab9a0 AL |
826 | */ |
827 | if (!(flg & TCP_FLAG_ACK)) | |
828 | return NULL; | |
ec0a1966 | 829 | |
8336886f JC |
830 | /* For Fast Open no more processing is needed (sk is the |
831 | * child socket). | |
832 | */ | |
833 | if (fastopen) | |
834 | return sk; | |
835 | ||
d1b99ba4 | 836 | /* While TCP_DEFER_ACCEPT is active, drop bare ACK. */ |
6e97ba55 | 837 | if (req->num_timeout < READ_ONCE(inet_csk(sk)->icsk_accept_queue.rskq_defer_accept) && |
2aaab9a0 AL |
838 | TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) { |
839 | inet_rsk(req)->acked = 1; | |
02a1d6e7 | 840 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPDEFERACCEPTDROP); |
2aaab9a0 AL |
841 | return NULL; |
842 | } | |
843 | ||
844 | /* OK, ACK is valid, create big socket and | |
845 | * feed this segment to it. It will repeat all | |
846 | * the tests. THIS SEGMENT MUST MOVE SOCKET TO | |
847 | * ESTABLISHED STATE. If it will be dropped after | |
848 | * socket is created, wait for troubles. | |
849 | */ | |
5e0724d0 ED |
850 | child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL, |
851 | req, &own_req); | |
51456b29 | 852 | if (!child) |
2aaab9a0 | 853 | goto listen_overflow; |
1da177e4 | 854 | |
90bf4513 | 855 | if (own_req && rsk_drop_req(req)) { |
d4f2c86b KI |
856 | reqsk_queue_removed(&inet_csk(req->rsk_listener)->icsk_accept_queue, req); |
857 | inet_csk_reqsk_queue_drop_and_put(req->rsk_listener, req); | |
f296234c PK |
858 | return child; |
859 | } | |
860 | ||
6bcfd7f8 | 861 | sock_rps_save_rxhash(child, skb); |
0f1c28ae | 862 | tcp_synack_rtt_meas(child, req); |
e0f9759f | 863 | *req_stolen = !own_req; |
5e0724d0 | 864 | return inet_csk_complete_hashdance(sk, child, req, own_req); |
1da177e4 | 865 | |
2aaab9a0 | 866 | listen_overflow: |
55d444b3 KI |
867 | if (sk != req->rsk_listener) |
868 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPMIGRATEREQFAILURE); | |
869 | ||
2d17d9c7 | 870 | if (!READ_ONCE(sock_net(sk)->ipv4.sysctl_tcp_abort_on_overflow)) { |
2aaab9a0 AL |
871 | inet_rsk(req)->acked = 1; |
872 | return NULL; | |
873 | } | |
1da177e4 | 874 | |
2aaab9a0 | 875 | embryonic_reset: |
8336886f JC |
876 | if (!(flg & TCP_FLAG_RST)) { |
877 | /* Received a bad SYN pkt - for TFO We try not to reset | |
878 | * the local connection unless it's really necessary to | |
879 | * avoid becoming vulnerable to outside attack aiming at | |
880 | * resetting legit local connections. | |
881 | */ | |
2aaab9a0 | 882 | req->rsk_ops->send_reset(sk, skb); |
8336886f JC |
883 | } else if (fastopen) { /* received a valid RST pkt */ |
884 | reqsk_fastopen_remove(sk, req, true); | |
049fe386 | 885 | tcp_reset(sk, skb); |
8336886f JC |
886 | } |
887 | if (!fastopen) { | |
7233da86 AO |
888 | bool unlinked = inet_csk_reqsk_queue_drop(sk, req); |
889 | ||
890 | if (unlinked) | |
891 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_EMBRYONICRSTS); | |
892 | *req_stolen = !unlinked; | |
8336886f | 893 | } |
2aaab9a0 | 894 | return NULL; |
1da177e4 | 895 | } |
4bc2f18b | 896 | EXPORT_SYMBOL(tcp_check_req); |
1da177e4 LT |
897 | |
898 | /* | |
899 | * Queue segment on the new socket if the new socket is active, | |
900 | * otherwise we just shortcircuit this and continue with | |
901 | * the new socket. | |
8336886f JC |
902 | * |
903 | * For the vast majority of cases child->sk_state will be TCP_SYN_RECV | |
904 | * when entering. But other states are possible due to a race condition | |
905 | * where after __inet_lookup_established() fails but before the listener | |
906 | * locked is obtained, other packets cause the same connection to | |
907 | * be created. | |
1da177e4 LT |
908 | */ |
909 | ||
b9825695 JX |
910 | enum skb_drop_reason tcp_child_process(struct sock *parent, struct sock *child, |
911 | struct sk_buff *skb) | |
734c8f75 | 912 | __releases(&((child)->sk_lock.slock)) |
1da177e4 | 913 | { |
b9825695 | 914 | enum skb_drop_reason reason = SKB_NOT_DROPPED_YET; |
1da177e4 LT |
915 | int state = child->sk_state; |
916 | ||
03cfda4f ED |
917 | /* record sk_napi_id and sk_rx_queue_mapping of child. */ |
918 | sk_mark_napi_id_set(child, skb); | |
e5907459 | 919 | |
a44d6eac | 920 | tcp_segs_in(tcp_sk(child), skb); |
1da177e4 | 921 | if (!sock_owned_by_user(child)) { |
b9825695 | 922 | reason = tcp_rcv_state_process(child, skb); |
1da177e4 LT |
923 | /* Wakeup parent, send SIGIO */ |
924 | if (state == TCP_SYN_RECV && child->sk_state != state) | |
676d2369 | 925 | parent->sk_data_ready(parent); |
1da177e4 LT |
926 | } else { |
927 | /* Alas, it is possible again, because we do lookup | |
928 | * in main socket hash table and lock on listening | |
929 | * socket does not protect us more. | |
930 | */ | |
a3a858ff | 931 | __sk_add_backlog(child, skb); |
1da177e4 LT |
932 | } |
933 | ||
934 | bh_unlock_sock(child); | |
935 | sock_put(child); | |
b9825695 | 936 | return reason; |
1da177e4 | 937 | } |
1da177e4 | 938 | EXPORT_SYMBOL(tcp_child_process); |