Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * INET An implementation of the TCP/IP protocol suite for the LINUX |
| 3 | * operating system. INET is implemented using the BSD Socket |
| 4 | * interface as the means of communication with the user level. |
| 5 | * |
| 6 | * Implementation of the Transmission Control Protocol(TCP). |
| 7 | * |
Jesper Juhl | 02c30a8 | 2005-05-05 16:16:16 -0700 | [diff] [blame] | 8 | * Authors: Ross Biro |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 9 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
| 10 | * Mark Evans, <evansmp@uhura.aston.ac.uk> |
| 11 | * Corey Minyard <wf-rch!minyard@relay.EU.net> |
| 12 | * Florian La Roche, <flla@stud.uni-sb.de> |
| 13 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> |
| 14 | * Linus Torvalds, <torvalds@cs.helsinki.fi> |
| 15 | * Alan Cox, <gw4pts@gw4pts.ampr.org> |
| 16 | * Matthew Dillon, <dillon@apollo.west.oic.com> |
| 17 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> |
| 18 | * Jorge Cwik, <jorge@laser.satlink.net> |
| 19 | */ |
| 20 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 21 | #include <linux/mm.h> |
| 22 | #include <linux/module.h> |
Tejun Heo | 5a0e3ad | 2010-03-24 17:04:11 +0900 | [diff] [blame] | 23 | #include <linux/slab.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 24 | #include <linux/sysctl.h> |
| 25 | #include <linux/workqueue.h> |
| 26 | #include <net/tcp.h> |
| 27 | #include <net/inet_common.h> |
| 28 | #include <net/xfrm.h> |
| 29 | |
David S. Miller | e994b7c | 2009-11-21 11:22:25 -0800 | [diff] [blame] | 30 | int sysctl_tcp_syncookies __read_mostly = 1; |
Glenn Griffin | c6aefaf | 2008-02-07 21:49:26 -0800 | [diff] [blame] | 31 | EXPORT_SYMBOL(sysctl_tcp_syncookies); |
| 32 | |
Brian Haley | ab32ea5 | 2006-09-22 14:15:41 -0700 | [diff] [blame] | 33 | int sysctl_tcp_abort_on_overflow __read_mostly; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 34 | |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 35 | struct inet_timewait_death_row tcp_death_row = { |
| 36 | .sysctl_max_tw_buckets = NR_FILE * 2, |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 37 | .hashinfo = &tcp_hashinfo, |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 38 | }; |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 39 | EXPORT_SYMBOL_GPL(tcp_death_row); |
| 40 | |
Eric Dumazet | a2a385d | 2012-05-16 23:15:34 +0000 | [diff] [blame] | 41 | static bool tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 42 | { |
| 43 | if (seq == s_win) |
Eric Dumazet | a2a385d | 2012-05-16 23:15:34 +0000 | [diff] [blame] | 44 | return true; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 45 | if (after(end_seq, s_win) && before(seq, e_win)) |
Eric Dumazet | a2a385d | 2012-05-16 23:15:34 +0000 | [diff] [blame] | 46 | return true; |
Eric Dumazet | a02cec2 | 2010-09-22 20:43:57 +0000 | [diff] [blame] | 47 | return seq == e_win && seq == end_seq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 48 | } |
| 49 | |
Neal Cardwell | 4fb17a6 | 2015-02-06 16:04:41 -0500 | [diff] [blame] | 50 | static enum tcp_tw_status |
| 51 | tcp_timewait_check_oow_rate_limit(struct inet_timewait_sock *tw, |
| 52 | const struct sk_buff *skb, int mib_idx) |
| 53 | { |
| 54 | struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); |
| 55 | |
| 56 | if (!tcp_oow_rate_limited(twsk_net(tw), skb, mib_idx, |
| 57 | &tcptw->tw_last_oow_ack_time)) { |
| 58 | /* Send ACK. Note, we do not put the bucket, |
| 59 | * it will be released by caller. |
| 60 | */ |
| 61 | return TCP_TW_ACK; |
| 62 | } |
| 63 | |
| 64 | /* We are rate-limiting, so just release the tw sock and drop skb. */ |
| 65 | inet_twsk_put(tw); |
| 66 | return TCP_TW_SUCCESS; |
| 67 | } |
| 68 | |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 69 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 70 | * * Main purpose of TIME-WAIT state is to close connection gracefully, |
| 71 | * when one of ends sits in LAST-ACK or CLOSING retransmitting FIN |
| 72 | * (and, probably, tail of data) and one or more our ACKs are lost. |
| 73 | * * What is TIME-WAIT timeout? It is associated with maximal packet |
| 74 | * lifetime in the internet, which results in wrong conclusion, that |
| 75 | * it is set to catch "old duplicate segments" wandering out of their path. |
| 76 | * It is not quite correct. This timeout is calculated so that it exceeds |
| 77 | * maximal retransmission timeout enough to allow to lose one (or more) |
| 78 | * segments sent by peer and our ACKs. This time may be calculated from RTO. |
| 79 | * * When TIME-WAIT socket receives RST, it means that another end |
| 80 | * finally closed and we are allowed to kill TIME-WAIT too. |
| 81 | * * Second purpose of TIME-WAIT is catching old duplicate segments. |
| 82 | * Well, certainly it is pure paranoia, but if we load TIME-WAIT |
| 83 | * with this semantics, we MUST NOT kill TIME-WAIT state with RSTs. |
| 84 | * * If we invented some more clever way to catch duplicates |
| 85 | * (f.e. based on PAWS), we could truncate TIME-WAIT to several RTOs. |
| 86 | * |
| 87 | * The algorithm below is based on FORMAL INTERPRETATION of RFCs. |
| 88 | * When you compare it to RFCs, please, read section SEGMENT ARRIVES |
| 89 | * from the very beginning. |
| 90 | * |
| 91 | * NOTE. With recycling (and later with fin-wait-2) TW bucket |
| 92 | * is _not_ stateless. It means, that strictly speaking we must |
| 93 | * spinlock it. I do not want! Well, probability of misbehaviour |
| 94 | * is ridiculously low and, seems, we could use some mb() tricks |
| 95 | * to avoid misread sequence numbers, states etc. --ANK |
Alan Cox | 4308fc5 | 2012-09-19 15:46:06 +0100 | [diff] [blame] | 96 | * |
| 97 | * We don't need to initialize tmp_out.sack_ok as we don't use the results |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 98 | */ |
| 99 | enum tcp_tw_status |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 100 | tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, |
| 101 | const struct tcphdr *th) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 102 | { |
| 103 | struct tcp_options_received tmp_opt; |
William Allen Simpson | 4957faade | 2009-12-02 18:25:27 +0000 | [diff] [blame] | 104 | struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); |
Eric Dumazet | a2a385d | 2012-05-16 23:15:34 +0000 | [diff] [blame] | 105 | bool paws_reject = false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 106 | |
David S. Miller | bb5b7c1 | 2009-12-15 20:56:42 -0800 | [diff] [blame] | 107 | tmp_opt.saw_tstamp = 0; |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 108 | if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) { |
Christoph Paasch | 1a2c618 | 2013-03-17 08:23:34 +0000 | [diff] [blame] | 109 | tcp_parse_options(skb, &tmp_opt, 0, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 110 | |
| 111 | if (tmp_opt.saw_tstamp) { |
Andrey Vagin | ee684b6 | 2013-02-11 05:50:19 +0000 | [diff] [blame] | 112 | tmp_opt.rcv_tsecr -= tcptw->tw_ts_offset; |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 113 | tmp_opt.ts_recent = tcptw->tw_ts_recent; |
| 114 | tmp_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; |
Ilpo Järvinen | c887e6d | 2009-03-14 14:23:03 +0000 | [diff] [blame] | 115 | paws_reject = tcp_paws_reject(&tmp_opt, th->rst); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 116 | } |
| 117 | } |
| 118 | |
| 119 | if (tw->tw_substate == TCP_FIN_WAIT2) { |
| 120 | /* Just repeat all the checks of tcp_rcv_state_process() */ |
| 121 | |
| 122 | /* Out of window, send ACK */ |
| 123 | if (paws_reject || |
| 124 | !tcp_in_window(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq, |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 125 | tcptw->tw_rcv_nxt, |
| 126 | tcptw->tw_rcv_nxt + tcptw->tw_rcv_wnd)) |
Neal Cardwell | 4fb17a6 | 2015-02-06 16:04:41 -0500 | [diff] [blame] | 127 | return tcp_timewait_check_oow_rate_limit( |
| 128 | tw, skb, LINUX_MIB_TCPACKSKIPPEDFINWAIT2); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 129 | |
| 130 | if (th->rst) |
| 131 | goto kill; |
| 132 | |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 133 | if (th->syn && !before(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | goto kill_with_rst; |
| 135 | |
| 136 | /* Dup ACK? */ |
Wei Yongjun | 1ac530b | 2009-06-24 22:29:31 +0000 | [diff] [blame] | 137 | if (!th->ack || |
| 138 | !after(TCP_SKB_CB(skb)->end_seq, tcptw->tw_rcv_nxt) || |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 139 | TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 140 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 141 | return TCP_TW_SUCCESS; |
| 142 | } |
| 143 | |
| 144 | /* New data or FIN. If new data arrive after half-duplex close, |
| 145 | * reset. |
| 146 | */ |
| 147 | if (!th->fin || |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 148 | TCP_SKB_CB(skb)->end_seq != tcptw->tw_rcv_nxt + 1) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 149 | kill_with_rst: |
Eric Dumazet | 789f558 | 2015-04-12 18:51:09 -0700 | [diff] [blame] | 150 | inet_twsk_deschedule(tw); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 151 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 152 | return TCP_TW_RST; |
| 153 | } |
| 154 | |
| 155 | /* FIN arrived, enter true time-wait state. */ |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 156 | tw->tw_substate = TCP_TIME_WAIT; |
| 157 | tcptw->tw_rcv_nxt = TCP_SKB_CB(skb)->end_seq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 158 | if (tmp_opt.saw_tstamp) { |
James Morris | 9d729f7 | 2007-03-04 16:12:44 -0800 | [diff] [blame] | 159 | tcptw->tw_ts_recent_stamp = get_seconds(); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 160 | tcptw->tw_ts_recent = tmp_opt.rcv_tsval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 161 | } |
| 162 | |
David S. Miller | ccb7c41 | 2010-12-01 18:09:13 -0800 | [diff] [blame] | 163 | if (tcp_death_row.sysctl_tw_recycle && |
| 164 | tcptw->tw_ts_recent_stamp && |
| 165 | tcp_tw_remember_stamp(tw)) |
Eric Dumazet | 789f558 | 2015-04-12 18:51:09 -0700 | [diff] [blame] | 166 | inet_twsk_schedule(tw, tw->tw_timeout); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 167 | else |
Eric Dumazet | 789f558 | 2015-04-12 18:51:09 -0700 | [diff] [blame] | 168 | inet_twsk_schedule(tw, TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 169 | return TCP_TW_ACK; |
| 170 | } |
| 171 | |
| 172 | /* |
| 173 | * Now real TIME-WAIT state. |
| 174 | * |
| 175 | * RFC 1122: |
| 176 | * "When a connection is [...] on TIME-WAIT state [...] |
| 177 | * [a TCP] MAY accept a new SYN from the remote TCP to |
| 178 | * reopen the connection directly, if it: |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 179 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 180 | * (1) assigns its initial sequence number for the new |
| 181 | * connection to be larger than the largest sequence |
| 182 | * number it used on the previous connection incarnation, |
| 183 | * and |
| 184 | * |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 185 | * (2) returns to TIME-WAIT state if the SYN turns out |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 186 | * to be an old duplicate". |
| 187 | */ |
| 188 | |
| 189 | if (!paws_reject && |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 190 | (TCP_SKB_CB(skb)->seq == tcptw->tw_rcv_nxt && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 191 | (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq || th->rst))) { |
| 192 | /* In window segment, it may be only reset or bare ack. */ |
| 193 | |
| 194 | if (th->rst) { |
Stephen Hemminger | caa20d9a | 2005-11-10 17:13:47 -0800 | [diff] [blame] | 195 | /* This is TIME_WAIT assassination, in two flavors. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 196 | * Oh well... nobody has a sufficient solution to this |
| 197 | * protocol bug yet. |
| 198 | */ |
| 199 | if (sysctl_tcp_rfc1337 == 0) { |
| 200 | kill: |
Eric Dumazet | 789f558 | 2015-04-12 18:51:09 -0700 | [diff] [blame] | 201 | inet_twsk_deschedule(tw); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 202 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 203 | return TCP_TW_SUCCESS; |
| 204 | } |
| 205 | } |
Eric Dumazet | 789f558 | 2015-04-12 18:51:09 -0700 | [diff] [blame] | 206 | inet_twsk_schedule(tw, TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 207 | |
| 208 | if (tmp_opt.saw_tstamp) { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 209 | tcptw->tw_ts_recent = tmp_opt.rcv_tsval; |
James Morris | 9d729f7 | 2007-03-04 16:12:44 -0800 | [diff] [blame] | 210 | tcptw->tw_ts_recent_stamp = get_seconds(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 211 | } |
| 212 | |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 213 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 214 | return TCP_TW_SUCCESS; |
| 215 | } |
| 216 | |
| 217 | /* Out of window segment. |
| 218 | |
| 219 | All the segments are ACKed immediately. |
| 220 | |
| 221 | The only exception is new SYN. We accept it, if it is |
| 222 | not old duplicate and we are not in danger to be killed |
| 223 | by delayed old duplicates. RFC check is that it has |
| 224 | newer sequence number works at rates <40Mbit/sec. |
| 225 | However, if paws works, it is reliable AND even more, |
| 226 | we even may relax silly seq space cutoff. |
| 227 | |
| 228 | RED-PEN: we violate main RFC requirement, if this SYN will appear |
| 229 | old duplicate (i.e. we receive RST in reply to SYN-ACK), |
| 230 | we must return socket to time-wait state. It is not good, |
| 231 | but not fatal yet. |
| 232 | */ |
| 233 | |
| 234 | if (th->syn && !th->rst && !th->ack && !paws_reject && |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 235 | (after(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt) || |
| 236 | (tmp_opt.saw_tstamp && |
| 237 | (s32)(tcptw->tw_ts_recent - tmp_opt.rcv_tsval) < 0))) { |
| 238 | u32 isn = tcptw->tw_snd_nxt + 65535 + 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 239 | if (isn == 0) |
| 240 | isn++; |
Eric Dumazet | 04317da | 2014-09-05 15:33:32 -0700 | [diff] [blame] | 241 | TCP_SKB_CB(skb)->tcp_tw_isn = isn; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 242 | return TCP_TW_SYN; |
| 243 | } |
| 244 | |
| 245 | if (paws_reject) |
Pavel Emelyanov | de0744a | 2008-07-16 20:31:16 -0700 | [diff] [blame] | 246 | NET_INC_STATS_BH(twsk_net(tw), LINUX_MIB_PAWSESTABREJECTED); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 247 | |
Stephen Hemminger | 2de979b | 2007-03-08 20:45:19 -0800 | [diff] [blame] | 248 | if (!th->rst) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 249 | /* In this case we must reset the TIMEWAIT timer. |
| 250 | * |
| 251 | * If it is ACKless SYN it may be both old duplicate |
| 252 | * and new good SYN with random sequence number <rcv_nxt. |
| 253 | * Do not reschedule in the last case. |
| 254 | */ |
| 255 | if (paws_reject || th->ack) |
Eric Dumazet | 789f558 | 2015-04-12 18:51:09 -0700 | [diff] [blame] | 256 | inet_twsk_schedule(tw, TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 257 | |
Neal Cardwell | 4fb17a6 | 2015-02-06 16:04:41 -0500 | [diff] [blame] | 258 | return tcp_timewait_check_oow_rate_limit( |
| 259 | tw, skb, LINUX_MIB_TCPACKSKIPPEDTIMEWAIT); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 260 | } |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 261 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 262 | return TCP_TW_SUCCESS; |
| 263 | } |
Eric Dumazet | 4bc2f18 | 2010-07-09 21:22:10 +0000 | [diff] [blame] | 264 | EXPORT_SYMBOL(tcp_timewait_state_process); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 265 | |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 266 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 267 | * Move a socket to time-wait or dead fin-wait-2 state. |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 268 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 269 | void tcp_time_wait(struct sock *sk, int state, int timeo) |
| 270 | { |
Arnaldo Carvalho de Melo | 8292a17 | 2005-12-13 23:15:52 -0800 | [diff] [blame] | 271 | const struct inet_connection_sock *icsk = inet_csk(sk); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 272 | const struct tcp_sock *tp = tcp_sk(sk); |
Eric Dumazet | 789f558 | 2015-04-12 18:51:09 -0700 | [diff] [blame] | 273 | struct inet_timewait_sock *tw; |
Eric Dumazet | a2a385d | 2012-05-16 23:15:34 +0000 | [diff] [blame] | 274 | bool recycle_ok = false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 275 | |
David S. Miller | b6242b9 | 2012-07-10 03:27:56 -0700 | [diff] [blame] | 276 | if (tcp_death_row.sysctl_tw_recycle && tp->rx_opt.ts_recent_stamp) |
David S. Miller | 3f419d2 | 2010-11-29 13:37:14 -0800 | [diff] [blame] | 277 | recycle_ok = tcp_remember_stamp(sk); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 278 | |
Eric Dumazet | 789f558 | 2015-04-12 18:51:09 -0700 | [diff] [blame] | 279 | tw = inet_twsk_alloc(sk, &tcp_death_row, state); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 280 | |
Ian Morris | 00db412 | 2015-04-03 09:17:27 +0100 | [diff] [blame] | 281 | if (tw) { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 282 | struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 283 | const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1); |
David S. Miller | 2397849 | 2012-06-09 14:56:12 -0700 | [diff] [blame] | 284 | struct inet_sock *inet = inet_sk(sk); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 285 | |
David S. Miller | 2397849 | 2012-06-09 14:56:12 -0700 | [diff] [blame] | 286 | tw->tw_transparent = inet->transparent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 287 | tw->tw_rcv_wscale = tp->rx_opt.rcv_wscale; |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 288 | tcptw->tw_rcv_nxt = tp->rcv_nxt; |
| 289 | tcptw->tw_snd_nxt = tp->snd_nxt; |
| 290 | tcptw->tw_rcv_wnd = tcp_receive_window(tp); |
| 291 | tcptw->tw_ts_recent = tp->rx_opt.ts_recent; |
| 292 | tcptw->tw_ts_recent_stamp = tp->rx_opt.ts_recent_stamp; |
Andrey Vagin | ceaa1fe | 2013-02-11 05:50:17 +0000 | [diff] [blame] | 293 | tcptw->tw_ts_offset = tp->tsoffset; |
Neal Cardwell | 4fb17a6 | 2015-02-06 16:04:41 -0500 | [diff] [blame] | 294 | tcptw->tw_last_oow_ack_time = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 295 | |
Eric Dumazet | dfd56b8 | 2011-12-10 09:48:31 +0000 | [diff] [blame] | 296 | #if IS_ENABLED(CONFIG_IPV6) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 297 | if (tw->tw_family == PF_INET6) { |
| 298 | struct ipv6_pinfo *np = inet6_sk(sk); |
| 299 | |
Eric Dumazet | efe4208 | 2013-10-03 15:42:29 -0700 | [diff] [blame] | 300 | tw->tw_v6_daddr = sk->sk_v6_daddr; |
| 301 | tw->tw_v6_rcv_saddr = sk->sk_v6_rcv_saddr; |
Eric Dumazet | b903d32 | 2011-10-27 00:44:35 -0400 | [diff] [blame] | 302 | tw->tw_tclass = np->tclass; |
Florent Fourcot | 1d13a96 | 2014-01-16 17:21:22 +0100 | [diff] [blame] | 303 | tw->tw_flowlabel = np->flow_label >> 12; |
Eric Dumazet | 9fe516b | 2014-06-27 08:36:16 -0700 | [diff] [blame] | 304 | tw->tw_ipv6only = sk->sk_ipv6only; |
Arnaldo Carvalho de Melo | c676270 | 2005-08-09 20:09:59 -0700 | [diff] [blame] | 305 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 306 | #endif |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 307 | |
| 308 | #ifdef CONFIG_TCP_MD5SIG |
| 309 | /* |
| 310 | * The timewait bucket does not have the key DB from the |
| 311 | * sock structure. We just make a quick copy of the |
| 312 | * md5 key being used (if indeed we are using one) |
| 313 | * so the timewait ack generating code has the key. |
| 314 | */ |
| 315 | do { |
| 316 | struct tcp_md5sig_key *key; |
Eric Dumazet | a915da9b | 2012-01-31 05:18:33 +0000 | [diff] [blame] | 317 | tcptw->tw_md5_key = NULL; |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 318 | key = tp->af_specific->md5_lookup(sk, sk); |
Ian Morris | 00db412 | 2015-04-03 09:17:27 +0100 | [diff] [blame] | 319 | if (key) { |
Eric Dumazet | a915da9b | 2012-01-31 05:18:33 +0000 | [diff] [blame] | 320 | tcptw->tw_md5_key = kmemdup(key, sizeof(*key), GFP_ATOMIC); |
Eric Dumazet | 71cea17 | 2013-05-20 06:52:26 +0000 | [diff] [blame] | 321 | if (tcptw->tw_md5_key && !tcp_alloc_md5sig_pool()) |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 322 | BUG(); |
| 323 | } |
Stephen Hemminger | 2de979b | 2007-03-08 20:45:19 -0800 | [diff] [blame] | 324 | } while (0); |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 325 | #endif |
| 326 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 327 | /* Linkage updates. */ |
Arnaldo Carvalho de Melo | e48c414 | 2005-08-09 20:09:46 -0700 | [diff] [blame] | 328 | __inet_twsk_hashdance(tw, sk, &tcp_hashinfo); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 329 | |
| 330 | /* Get the TIME_WAIT timeout firing. */ |
| 331 | if (timeo < rto) |
| 332 | timeo = rto; |
| 333 | |
| 334 | if (recycle_ok) { |
| 335 | tw->tw_timeout = rto; |
| 336 | } else { |
| 337 | tw->tw_timeout = TCP_TIMEWAIT_LEN; |
| 338 | if (state == TCP_TIME_WAIT) |
| 339 | timeo = TCP_TIMEWAIT_LEN; |
| 340 | } |
| 341 | |
Eric Dumazet | 789f558 | 2015-04-12 18:51:09 -0700 | [diff] [blame] | 342 | inet_twsk_schedule(tw, timeo); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 343 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 344 | } else { |
| 345 | /* Sorry, if we're out of memory, just CLOSE this |
| 346 | * socket up. We've got bigger problems than |
| 347 | * non-graceful socket closings. |
| 348 | */ |
Tom Herbert | 6763151 | 2010-12-08 12:16:33 -0800 | [diff] [blame] | 349 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPTIMEWAITOVERFLOW); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 350 | } |
| 351 | |
| 352 | tcp_update_metrics(sk); |
| 353 | tcp_done(sk); |
| 354 | } |
| 355 | |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 356 | void tcp_twsk_destructor(struct sock *sk) |
| 357 | { |
David S. Miller | b6242b9 | 2012-07-10 03:27:56 -0700 | [diff] [blame] | 358 | #ifdef CONFIG_TCP_MD5SIG |
David S. Miller | a928630 | 2006-11-14 19:53:22 -0800 | [diff] [blame] | 359 | struct tcp_timewait_sock *twsk = tcp_twsk(sk); |
David S. Miller | 2397849 | 2012-06-09 14:56:12 -0700 | [diff] [blame] | 360 | |
Eric Dumazet | 71cea17 | 2013-05-20 06:52:26 +0000 | [diff] [blame] | 361 | if (twsk->tw_md5_key) |
Eric Dumazet | a915da9b | 2012-01-31 05:18:33 +0000 | [diff] [blame] | 362 | kfree_rcu(twsk->tw_md5_key, rcu); |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 363 | #endif |
| 364 | } |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 365 | EXPORT_SYMBOL_GPL(tcp_twsk_destructor); |
| 366 | |
Yuchung Cheng | 843f4a5 | 2014-05-11 20:22:11 -0700 | [diff] [blame] | 367 | void tcp_openreq_init_rwin(struct request_sock *req, |
| 368 | struct sock *sk, struct dst_entry *dst) |
| 369 | { |
| 370 | struct inet_request_sock *ireq = inet_rsk(req); |
| 371 | struct tcp_sock *tp = tcp_sk(sk); |
| 372 | __u8 rcv_wscale; |
| 373 | int mss = dst_metric_advmss(dst); |
| 374 | |
| 375 | if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss) |
| 376 | mss = tp->rx_opt.user_mss; |
| 377 | |
| 378 | /* Set this up on the first call only */ |
| 379 | req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW); |
| 380 | |
| 381 | /* limit the window selection if the user enforce a smaller rx buffer */ |
| 382 | if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && |
| 383 | (req->window_clamp > tcp_full_space(sk) || req->window_clamp == 0)) |
| 384 | req->window_clamp = tcp_full_space(sk); |
| 385 | |
| 386 | /* tcp_full_space because it is guaranteed to be the first packet */ |
| 387 | tcp_select_initial_window(tcp_full_space(sk), |
| 388 | mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0), |
| 389 | &req->rcv_wnd, |
| 390 | &req->window_clamp, |
| 391 | ireq->wscale_ok, |
| 392 | &rcv_wscale, |
| 393 | dst_metric(dst, RTAX_INITRWND)); |
| 394 | ireq->rcv_wscale = rcv_wscale; |
| 395 | } |
| 396 | EXPORT_SYMBOL(tcp_openreq_init_rwin); |
| 397 | |
Florian Westphal | 735d383 | 2014-09-29 13:08:30 +0200 | [diff] [blame] | 398 | static void tcp_ecn_openreq_child(struct tcp_sock *tp, |
| 399 | const struct request_sock *req) |
Ilpo Järvinen | bdf1ee5 | 2007-05-27 02:04:16 -0700 | [diff] [blame] | 400 | { |
| 401 | tp->ecn_flags = inet_rsk(req)->ecn_ok ? TCP_ECN_OK : 0; |
| 402 | } |
| 403 | |
Daniel Borkmann | 8116441 | 2015-01-05 23:57:48 +0100 | [diff] [blame] | 404 | void tcp_ca_openreq_child(struct sock *sk, const struct dst_entry *dst) |
| 405 | { |
| 406 | struct inet_connection_sock *icsk = inet_csk(sk); |
| 407 | u32 ca_key = dst_metric(dst, RTAX_CC_ALGO); |
| 408 | bool ca_got_dst = false; |
| 409 | |
| 410 | if (ca_key != TCP_CA_UNSPEC) { |
| 411 | const struct tcp_congestion_ops *ca; |
| 412 | |
| 413 | rcu_read_lock(); |
| 414 | ca = tcp_ca_find_key(ca_key); |
| 415 | if (likely(ca && try_module_get(ca->owner))) { |
| 416 | icsk->icsk_ca_dst_locked = tcp_ca_dst_locked(dst); |
| 417 | icsk->icsk_ca_ops = ca; |
| 418 | ca_got_dst = true; |
| 419 | } |
| 420 | rcu_read_unlock(); |
| 421 | } |
| 422 | |
| 423 | if (!ca_got_dst && !try_module_get(icsk->icsk_ca_ops->owner)) |
| 424 | tcp_assign_congestion_control(sk); |
| 425 | |
| 426 | tcp_set_ca_state(sk, TCP_CA_Open); |
| 427 | } |
| 428 | EXPORT_SYMBOL_GPL(tcp_ca_openreq_child); |
| 429 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 430 | /* This is not only more efficient than what we used to do, it eliminates |
| 431 | * a lot of code duplication between IPv4/IPv6 SYN recv processing. -DaveM |
| 432 | * |
| 433 | * Actually, we could lots of memory writes here. tp of listening |
| 434 | * socket contains all necessary default parameters. |
| 435 | */ |
Arnaldo Carvalho de Melo | 60236fd | 2005-06-18 22:47:21 -0700 | [diff] [blame] | 436 | struct sock *tcp_create_openreq_child(struct sock *sk, struct request_sock *req, struct sk_buff *skb) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 437 | { |
Eric Dumazet | e56c57d | 2011-11-08 17:07:07 -0500 | [diff] [blame] | 438 | struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 439 | |
Ian Morris | 00db412 | 2015-04-03 09:17:27 +0100 | [diff] [blame] | 440 | if (newsk) { |
Arnaldo Carvalho de Melo | 9f1d260 | 2005-08-09 20:11:24 -0700 | [diff] [blame] | 441 | const struct inet_request_sock *ireq = inet_rsk(req); |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 442 | struct tcp_request_sock *treq = tcp_rsk(req); |
Arnaldo Carvalho de Melo | a9948a7 | 2007-02-28 11:05:56 -0800 | [diff] [blame] | 443 | struct inet_connection_sock *newicsk = inet_csk(newsk); |
William Allen Simpson | 435cf55 | 2009-12-02 18:17:05 +0000 | [diff] [blame] | 444 | struct tcp_sock *newtp = tcp_sk(newsk); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 445 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 446 | /* Now setup tcp_sock */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 447 | newtp->pred_flags = 0; |
William Allen Simpson | 435cf55 | 2009-12-02 18:17:05 +0000 | [diff] [blame] | 448 | |
| 449 | newtp->rcv_wup = newtp->copied_seq = |
| 450 | newtp->rcv_nxt = treq->rcv_isn + 1; |
| 451 | |
| 452 | newtp->snd_sml = newtp->snd_una = |
Christoph Paasch | 1a2c618 | 2013-03-17 08:23:34 +0000 | [diff] [blame] | 453 | newtp->snd_nxt = newtp->snd_up = treq->snt_isn + 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 454 | |
| 455 | tcp_prequeue_init(newtp); |
Eric Dumazet | 46d3cea | 2012-07-11 05:50:31 +0000 | [diff] [blame] | 456 | INIT_LIST_HEAD(&newtp->tsq_node); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 457 | |
Hantzis Fotis | ee7537b | 2009-03-02 22:42:02 -0800 | [diff] [blame] | 458 | tcp_init_wl(newtp, treq->rcv_isn); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 459 | |
Eric Dumazet | 740b0f1 | 2014-02-26 14:02:48 -0800 | [diff] [blame] | 460 | newtp->srtt_us = 0; |
| 461 | newtp->mdev_us = jiffies_to_usecs(TCP_TIMEOUT_INIT); |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 462 | newicsk->icsk_rto = TCP_TIMEOUT_INIT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 463 | |
| 464 | newtp->packets_out = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 465 | newtp->retrans_out = 0; |
| 466 | newtp->sacked_out = 0; |
| 467 | newtp->fackets_out = 0; |
Ilpo Järvinen | 0b6a05c | 2009-09-15 01:30:10 -0700 | [diff] [blame] | 468 | newtp->snd_ssthresh = TCP_INFINITE_SSTHRESH; |
Yuchung Cheng | eed530b | 2012-05-02 13:30:03 +0000 | [diff] [blame] | 469 | tcp_enable_early_retrans(newtp); |
Nandita Dukkipati | 9b717a8 | 2013-03-11 10:00:44 +0000 | [diff] [blame] | 470 | newtp->tlp_high_seq = 0; |
Yuchung Cheng | 375fe02 | 2013-07-22 16:20:45 -0700 | [diff] [blame] | 471 | newtp->lsndtime = treq->snt_synack; |
Neal Cardwell | f2b2c58 | 2015-02-06 16:04:40 -0500 | [diff] [blame] | 472 | newtp->last_oow_ack_time = 0; |
Yuchung Cheng | 375fe02 | 2013-07-22 16:20:45 -0700 | [diff] [blame] | 473 | newtp->total_retrans = req->num_retrans; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 474 | |
| 475 | /* So many TCP implementations out there (incorrectly) count the |
| 476 | * initial SYN frame in their delayed-ACK and congestion control |
| 477 | * algorithms that we must have the following bandaid to talk |
| 478 | * efficiently to them. -DaveM |
| 479 | */ |
Jerry Chu | 9ad7c04 | 2011-06-08 11:08:38 +0000 | [diff] [blame] | 480 | newtp->snd_cwnd = TCP_INIT_CWND; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 481 | newtp->snd_cwnd_cnt = 0; |
| 482 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 483 | tcp_init_xmit_timers(newsk); |
Eric Dumazet | 996b175 | 2014-01-06 09:36:12 -0800 | [diff] [blame] | 484 | __skb_queue_head_init(&newtp->out_of_order_queue); |
Christoph Paasch | 1a2c618 | 2013-03-17 08:23:34 +0000 | [diff] [blame] | 485 | newtp->write_seq = newtp->pushed_seq = treq->snt_isn + 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 486 | |
| 487 | newtp->rx_opt.saw_tstamp = 0; |
| 488 | |
| 489 | newtp->rx_opt.dsack = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 490 | newtp->rx_opt.num_sacks = 0; |
Ilpo Järvinen | cabeccb | 2009-02-28 04:44:38 +0000 | [diff] [blame] | 491 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 492 | newtp->urg_data = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 493 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 494 | if (sock_flag(newsk, SOCK_KEEPOPEN)) |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 495 | inet_csk_reset_keepalive_timer(newsk, |
| 496 | keepalive_time_when(newtp)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 497 | |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 498 | newtp->rx_opt.tstamp_ok = ireq->tstamp_ok; |
Stephen Hemminger | 2de979b | 2007-03-08 20:45:19 -0800 | [diff] [blame] | 499 | if ((newtp->rx_opt.sack_ok = ireq->sack_ok) != 0) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 500 | if (sysctl_tcp_fack) |
Ilpo Järvinen | e60402d | 2007-08-09 15:14:46 +0300 | [diff] [blame] | 501 | tcp_enable_fack(newtp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 502 | } |
| 503 | newtp->window_clamp = req->window_clamp; |
| 504 | newtp->rcv_ssthresh = req->rcv_wnd; |
| 505 | newtp->rcv_wnd = req->rcv_wnd; |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 506 | newtp->rx_opt.wscale_ok = ireq->wscale_ok; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 507 | if (newtp->rx_opt.wscale_ok) { |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 508 | newtp->rx_opt.snd_wscale = ireq->snd_wscale; |
| 509 | newtp->rx_opt.rcv_wscale = ireq->rcv_wscale; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 510 | } else { |
| 511 | newtp->rx_opt.snd_wscale = newtp->rx_opt.rcv_wscale = 0; |
| 512 | newtp->window_clamp = min(newtp->window_clamp, 65535U); |
| 513 | } |
Arnaldo Carvalho de Melo | aa8223c | 2007-04-10 21:04:22 -0700 | [diff] [blame] | 514 | newtp->snd_wnd = (ntohs(tcp_hdr(skb)->window) << |
| 515 | newtp->rx_opt.snd_wscale); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 516 | newtp->max_window = newtp->snd_wnd; |
| 517 | |
| 518 | if (newtp->rx_opt.tstamp_ok) { |
| 519 | newtp->rx_opt.ts_recent = req->ts_recent; |
James Morris | 9d729f7 | 2007-03-04 16:12:44 -0800 | [diff] [blame] | 520 | newtp->rx_opt.ts_recent_stamp = get_seconds(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 521 | newtp->tcp_header_len = sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED; |
| 522 | } else { |
| 523 | newtp->rx_opt.ts_recent_stamp = 0; |
| 524 | newtp->tcp_header_len = sizeof(struct tcphdr); |
| 525 | } |
Andrey Vagin | ceaa1fe | 2013-02-11 05:50:17 +0000 | [diff] [blame] | 526 | newtp->tsoffset = 0; |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 527 | #ifdef CONFIG_TCP_MD5SIG |
| 528 | newtp->md5sig_info = NULL; /*XXX*/ |
| 529 | if (newtp->af_specific->md5_lookup(sk, newsk)) |
| 530 | newtp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; |
| 531 | #endif |
William Allen Simpson | bee7ca9 | 2009-11-10 09:51:18 +0000 | [diff] [blame] | 532 | if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len) |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 533 | newicsk->icsk_ack.last_seg_size = skb->len - newtp->tcp_header_len; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 534 | newtp->rx_opt.mss_clamp = req->mss; |
Florian Westphal | 735d383 | 2014-09-29 13:08:30 +0200 | [diff] [blame] | 535 | tcp_ecn_openreq_child(newtp, req); |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 536 | newtp->fastopen_rsk = NULL; |
Yuchung Cheng | 6f73601 | 2012-10-19 15:14:44 +0000 | [diff] [blame] | 537 | newtp->syn_data_acked = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 538 | |
Pavel Emelyanov | 63231bd | 2008-07-16 20:22:25 -0700 | [diff] [blame] | 539 | TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_PASSIVEOPENS); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 540 | } |
| 541 | return newsk; |
| 542 | } |
Eric Dumazet | 4bc2f18 | 2010-07-09 21:22:10 +0000 | [diff] [blame] | 543 | EXPORT_SYMBOL(tcp_create_openreq_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 544 | |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 545 | /* |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 546 | * Process an incoming packet for SYN_RECV sockets represented as a |
| 547 | * request_sock. Normally sk is the listener socket but for TFO it |
| 548 | * points to the child socket. |
| 549 | * |
| 550 | * XXX (TFO) - The current impl contains a special check for ack |
| 551 | * validation and inside tcp_v4_reqsk_send_ack(). Can we do better? |
Alan Cox | 4308fc5 | 2012-09-19 15:46:06 +0100 | [diff] [blame] | 552 | * |
| 553 | * We don't need to initialize tmp_opt.sack_ok as we don't use the results |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 554 | */ |
| 555 | |
Jianjun Kong | 5a5f3a8 | 2008-11-03 00:24:34 -0800 | [diff] [blame] | 556 | struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, |
Arnaldo Carvalho de Melo | 60236fd | 2005-06-18 22:47:21 -0700 | [diff] [blame] | 557 | struct request_sock *req, |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 558 | bool fastopen) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 559 | { |
William Allen Simpson | 4957faade | 2009-12-02 18:25:27 +0000 | [diff] [blame] | 560 | struct tcp_options_received tmp_opt; |
William Allen Simpson | 4957faade | 2009-12-02 18:25:27 +0000 | [diff] [blame] | 561 | struct sock *child; |
Arnaldo Carvalho de Melo | aa8223c | 2007-04-10 21:04:22 -0700 | [diff] [blame] | 562 | const struct tcphdr *th = tcp_hdr(skb); |
Al Viro | 714e85b | 2006-11-14 20:51:49 -0800 | [diff] [blame] | 563 | __be32 flg = tcp_flag_word(th) & (TCP_FLAG_RST|TCP_FLAG_SYN|TCP_FLAG_ACK); |
Eric Dumazet | a2a385d | 2012-05-16 23:15:34 +0000 | [diff] [blame] | 564 | bool paws_reject = false; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 565 | |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 566 | BUG_ON(fastopen == (sk->sk_state == TCP_LISTEN)); |
| 567 | |
David S. Miller | bb5b7c1 | 2009-12-15 20:56:42 -0800 | [diff] [blame] | 568 | tmp_opt.saw_tstamp = 0; |
| 569 | if (th->doff > (sizeof(struct tcphdr)>>2)) { |
Christoph Paasch | 1a2c618 | 2013-03-17 08:23:34 +0000 | [diff] [blame] | 570 | tcp_parse_options(skb, &tmp_opt, 0, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 571 | |
| 572 | if (tmp_opt.saw_tstamp) { |
| 573 | tmp_opt.ts_recent = req->ts_recent; |
| 574 | /* We do not store true stamp, but it is not required, |
| 575 | * it can be estimated (approximately) |
| 576 | * from another data. |
| 577 | */ |
Eric Dumazet | e6c022a | 2012-10-27 23:16:46 +0000 | [diff] [blame] | 578 | tmp_opt.ts_recent_stamp = get_seconds() - ((TCP_TIMEOUT_INIT/HZ)<<req->num_timeout); |
Ilpo Järvinen | c887e6d | 2009-03-14 14:23:03 +0000 | [diff] [blame] | 579 | paws_reject = tcp_paws_reject(&tmp_opt, th->rst); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 580 | } |
| 581 | } |
| 582 | |
| 583 | /* Check for pure retransmitted SYN. */ |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 584 | if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 585 | flg == TCP_FLAG_SYN && |
| 586 | !paws_reject) { |
| 587 | /* |
| 588 | * RFC793 draws (Incorrectly! It was fixed in RFC1122) |
| 589 | * this case on figure 6 and figure 8, but formal |
| 590 | * protocol description says NOTHING. |
| 591 | * To be more exact, it says that we should send ACK, |
| 592 | * because this segment (at least, if it has no data) |
| 593 | * is out of window. |
| 594 | * |
| 595 | * CONCLUSION: RFC793 (even with RFC1122) DOES NOT |
| 596 | * describe SYN-RECV state. All the description |
| 597 | * is wrong, we cannot believe to it and should |
| 598 | * rely only on common sense and implementation |
| 599 | * experience. |
| 600 | * |
| 601 | * Enforce "SYN-ACK" according to figure 8, figure 6 |
| 602 | * of RFC793, fixed by RFC1122. |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 603 | * |
| 604 | * Note that even if there is new data in the SYN packet |
| 605 | * they will be thrown away too. |
Yuchung Cheng | cd75eff | 2013-04-29 08:44:51 +0000 | [diff] [blame] | 606 | * |
| 607 | * Reset timer after retransmitting SYNACK, similar to |
| 608 | * the idea of fast retransmit in recovery. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 609 | */ |
Neal Cardwell | a9b2c06 | 2015-02-06 16:04:39 -0500 | [diff] [blame] | 610 | if (!tcp_oow_rate_limited(sock_net(sk), skb, |
| 611 | LINUX_MIB_TCPACKSKIPPEDSYNRECV, |
| 612 | &tcp_rsk(req)->last_oow_ack_time) && |
| 613 | |
Eric Dumazet | dd929c1 | 2015-04-08 15:34:04 -0700 | [diff] [blame] | 614 | !inet_rtx_syn_ack(sk, req)) { |
| 615 | unsigned long expires = jiffies; |
| 616 | |
| 617 | expires += min(TCP_TIMEOUT_INIT << req->num_timeout, |
| 618 | TCP_RTO_MAX); |
| 619 | if (!fastopen) |
| 620 | mod_timer_pending(&req->rsk_timer, expires); |
| 621 | else |
| 622 | req->rsk_timer.expires = expires; |
| 623 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 624 | return NULL; |
| 625 | } |
| 626 | |
| 627 | /* Further reproduces section "SEGMENT ARRIVES" |
| 628 | for state SYN-RECEIVED of RFC793. |
| 629 | It is broken, however, it does not work only |
| 630 | when SYNs are crossed. |
| 631 | |
| 632 | You would think that SYN crossing is impossible here, since |
| 633 | we should have a SYN_SENT socket (from connect()) on our end, |
| 634 | but this is not true if the crossed SYNs were sent to both |
| 635 | ends by a malicious third party. We must defend against this, |
| 636 | and to do that we first verify the ACK (as per RFC793, page |
| 637 | 36) and reset if it is invalid. Is this a true full defense? |
| 638 | To convince ourselves, let us consider a way in which the ACK |
| 639 | test can still pass in this 'malicious crossed SYNs' case. |
| 640 | Malicious sender sends identical SYNs (and thus identical sequence |
| 641 | numbers) to both A and B: |
| 642 | |
| 643 | A: gets SYN, seq=7 |
| 644 | B: gets SYN, seq=7 |
| 645 | |
| 646 | By our good fortune, both A and B select the same initial |
| 647 | send sequence number of seven :-) |
| 648 | |
| 649 | A: sends SYN|ACK, seq=7, ack_seq=8 |
| 650 | B: sends SYN|ACK, seq=7, ack_seq=8 |
| 651 | |
| 652 | So we are now A eating this SYN|ACK, ACK test passes. So |
| 653 | does sequence test, SYN is truncated, and thus we consider |
| 654 | it a bare ACK. |
| 655 | |
David S. Miller | ec0a196 | 2008-06-12 16:31:35 -0700 | [diff] [blame] | 656 | If icsk->icsk_accept_queue.rskq_defer_accept, we silently drop this |
| 657 | bare ACK. Otherwise, we create an established connection. Both |
| 658 | ends (listening sockets) accept the new incoming connection and try |
| 659 | to talk to each other. 8-) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 660 | |
| 661 | Note: This case is both harmless, and rare. Possibility is about the |
| 662 | same as us discovering intelligent life on another plant tomorrow. |
| 663 | |
| 664 | But generally, we should (RFC lies!) to accept ACK |
| 665 | from SYNACK both here and in tcp_rcv_state_process(). |
| 666 | tcp_rcv_state_process() does not, hence, we do not too. |
| 667 | |
| 668 | Note that the case is absolutely generic: |
| 669 | we cannot optimize anything here without |
| 670 | violating protocol. All the checks must be made |
| 671 | before attempt to create socket. |
| 672 | */ |
| 673 | |
| 674 | /* RFC793 page 36: "If the connection is in any non-synchronized state ... |
| 675 | * and the incoming segment acknowledges something not yet |
Stephen Hemminger | caa20d9a | 2005-11-10 17:13:47 -0800 | [diff] [blame] | 676 | * sent (the segment carries an unacceptable ACK) ... |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 677 | * a reset is sent." |
| 678 | * |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 679 | * Invalid ACK: reset will be sent by listening socket. |
| 680 | * Note that the ACK validity check for a Fast Open socket is done |
| 681 | * elsewhere and is checked directly against the child socket rather |
| 682 | * than req because user data may have been sent out. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 683 | */ |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 684 | if ((flg & TCP_FLAG_ACK) && !fastopen && |
William Allen Simpson | 435cf55 | 2009-12-02 18:17:05 +0000 | [diff] [blame] | 685 | (TCP_SKB_CB(skb)->ack_seq != |
Christoph Paasch | 1a2c618 | 2013-03-17 08:23:34 +0000 | [diff] [blame] | 686 | tcp_rsk(req)->snt_isn + 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 687 | return sk; |
| 688 | |
| 689 | /* Also, it would be not so bad idea to check rcv_tsecr, which |
| 690 | * is essentially ACK extension and too early or too late values |
| 691 | * should cause reset in unsynchronized states. |
| 692 | */ |
| 693 | |
| 694 | /* RFC793: "first check sequence number". */ |
| 695 | |
| 696 | if (paws_reject || !tcp_in_window(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq, |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 697 | tcp_rsk(req)->rcv_nxt, tcp_rsk(req)->rcv_nxt + req->rcv_wnd)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 698 | /* Out of window: send ACK and drop. */ |
| 699 | if (!(flg & TCP_FLAG_RST)) |
Gui Jianfeng | 6edafaa | 2008-08-06 23:50:04 -0700 | [diff] [blame] | 700 | req->rsk_ops->send_ack(sk, skb, req); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 701 | if (paws_reject) |
Pavel Emelyanov | de0744a | 2008-07-16 20:31:16 -0700 | [diff] [blame] | 702 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 703 | return NULL; |
| 704 | } |
| 705 | |
| 706 | /* In sequence, PAWS is OK. */ |
| 707 | |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 708 | if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_nxt)) |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 709 | req->ts_recent = tmp_opt.rcv_tsval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 710 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 711 | if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) { |
| 712 | /* Truncate SYN, it is out of window starting |
| 713 | at tcp_rsk(req)->rcv_isn + 1. */ |
| 714 | flg &= ~TCP_FLAG_SYN; |
| 715 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 716 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 717 | /* RFC793: "second check the RST bit" and |
| 718 | * "fourth, check the SYN bit" |
| 719 | */ |
| 720 | if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN)) { |
| 721 | TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS); |
| 722 | goto embryonic_reset; |
| 723 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 724 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 725 | /* ACK sequence verified above, just make sure ACK is |
| 726 | * set. If ACK not set, just silently drop the packet. |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 727 | * |
| 728 | * XXX (TFO) - if we ever allow "data after SYN", the |
| 729 | * following check needs to be removed. |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 730 | */ |
| 731 | if (!(flg & TCP_FLAG_ACK)) |
| 732 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 733 | |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 734 | /* For Fast Open no more processing is needed (sk is the |
| 735 | * child socket). |
| 736 | */ |
| 737 | if (fastopen) |
| 738 | return sk; |
| 739 | |
Julian Anastasov | d1b99ba | 2009-10-19 10:01:56 +0000 | [diff] [blame] | 740 | /* While TCP_DEFER_ACCEPT is active, drop bare ACK. */ |
Eric Dumazet | e6c022a | 2012-10-27 23:16:46 +0000 | [diff] [blame] | 741 | if (req->num_timeout < inet_csk(sk)->icsk_accept_queue.rskq_defer_accept && |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 742 | TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) { |
| 743 | inet_rsk(req)->acked = 1; |
Eric Dumazet | 907cdda | 2010-03-19 05:37:18 +0000 | [diff] [blame] | 744 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDEFERACCEPTDROP); |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 745 | return NULL; |
| 746 | } |
David S. Miller | ec0a196 | 2008-06-12 16:31:35 -0700 | [diff] [blame] | 747 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 748 | /* OK, ACK is valid, create big socket and |
| 749 | * feed this segment to it. It will repeat all |
| 750 | * the tests. THIS SEGMENT MUST MOVE SOCKET TO |
| 751 | * ESTABLISHED STATE. If it will be dropped after |
| 752 | * socket is created, wait for troubles. |
| 753 | */ |
| 754 | child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL); |
Ian Morris | 51456b2 | 2015-04-03 09:17:26 +0100 | [diff] [blame] | 755 | if (!child) |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 756 | goto listen_overflow; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 757 | |
Eric Dumazet | b357a36 | 2015-04-23 18:03:44 -0700 | [diff] [blame] | 758 | inet_csk_reqsk_queue_drop(sk, req); |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 759 | inet_csk_reqsk_queue_add(sk, req, child); |
Eric Dumazet | b357a36 | 2015-04-23 18:03:44 -0700 | [diff] [blame] | 760 | /* Warning: caller must not call reqsk_put(req); |
| 761 | * child stole last reference on it. |
| 762 | */ |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 763 | return child; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 764 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 765 | listen_overflow: |
| 766 | if (!sysctl_tcp_abort_on_overflow) { |
| 767 | inet_rsk(req)->acked = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 768 | return NULL; |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 769 | } |
| 770 | |
| 771 | embryonic_reset: |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 772 | if (!(flg & TCP_FLAG_RST)) { |
| 773 | /* Received a bad SYN pkt - for TFO We try not to reset |
| 774 | * the local connection unless it's really necessary to |
| 775 | * avoid becoming vulnerable to outside attack aiming at |
| 776 | * resetting legit local connections. |
| 777 | */ |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 778 | req->rsk_ops->send_reset(sk, skb); |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 779 | } else if (fastopen) { /* received a valid RST pkt */ |
| 780 | reqsk_fastopen_remove(sk, req, true); |
| 781 | tcp_reset(sk); |
| 782 | } |
| 783 | if (!fastopen) { |
Eric Dumazet | 52452c5 | 2015-03-19 19:04:19 -0700 | [diff] [blame] | 784 | inet_csk_reqsk_queue_drop(sk, req); |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 785 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_EMBRYONICRSTS); |
| 786 | } |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 787 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 788 | } |
Eric Dumazet | 4bc2f18 | 2010-07-09 21:22:10 +0000 | [diff] [blame] | 789 | EXPORT_SYMBOL(tcp_check_req); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 790 | |
| 791 | /* |
| 792 | * Queue segment on the new socket if the new socket is active, |
| 793 | * otherwise we just shortcircuit this and continue with |
| 794 | * the new socket. |
Jerry Chu | 8336886 | 2012-08-31 12:29:12 +0000 | [diff] [blame] | 795 | * |
| 796 | * For the vast majority of cases child->sk_state will be TCP_SYN_RECV |
| 797 | * when entering. But other states are possible due to a race condition |
| 798 | * where after __inet_lookup_established() fails but before the listener |
| 799 | * locked is obtained, other packets cause the same connection to |
| 800 | * be created. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 801 | */ |
| 802 | |
| 803 | int tcp_child_process(struct sock *parent, struct sock *child, |
| 804 | struct sk_buff *skb) |
| 805 | { |
| 806 | int ret = 0; |
| 807 | int state = child->sk_state; |
| 808 | |
| 809 | if (!sock_owned_by_user(child)) { |
Arnaldo Carvalho de Melo | aa8223c | 2007-04-10 21:04:22 -0700 | [diff] [blame] | 810 | ret = tcp_rcv_state_process(child, skb, tcp_hdr(skb), |
| 811 | skb->len); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 812 | /* Wakeup parent, send SIGIO */ |
| 813 | if (state == TCP_SYN_RECV && child->sk_state != state) |
David S. Miller | 676d236 | 2014-04-11 16:15:36 -0400 | [diff] [blame] | 814 | parent->sk_data_ready(parent); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 815 | } else { |
| 816 | /* Alas, it is possible again, because we do lookup |
| 817 | * in main socket hash table and lock on listening |
| 818 | * socket does not protect us more. |
| 819 | */ |
Zhu Yi | a3a858f | 2010-03-04 18:01:47 +0000 | [diff] [blame] | 820 | __sk_add_backlog(child, skb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 821 | } |
| 822 | |
| 823 | bh_unlock_sock(child); |
| 824 | sock_put(child); |
| 825 | return ret; |
| 826 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 827 | EXPORT_SYMBOL(tcp_child_process); |