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 | * |
| 8 | * Version: $Id: tcp_minisocks.c,v 1.15 2002/02/01 22:01:04 davem Exp $ |
| 9 | * |
Jesper Juhl | 02c30a8 | 2005-05-05 16:16:16 -0700 | [diff] [blame] | 10 | * Authors: Ross Biro |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 11 | * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG> |
| 12 | * Mark Evans, <evansmp@uhura.aston.ac.uk> |
| 13 | * Corey Minyard <wf-rch!minyard@relay.EU.net> |
| 14 | * Florian La Roche, <flla@stud.uni-sb.de> |
| 15 | * Charles Hedrick, <hedrick@klinzhai.rutgers.edu> |
| 16 | * Linus Torvalds, <torvalds@cs.helsinki.fi> |
| 17 | * Alan Cox, <gw4pts@gw4pts.ampr.org> |
| 18 | * Matthew Dillon, <dillon@apollo.west.oic.com> |
| 19 | * Arnt Gulbrandsen, <agulbra@nvg.unit.no> |
| 20 | * Jorge Cwik, <jorge@laser.satlink.net> |
| 21 | */ |
| 22 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 23 | #include <linux/mm.h> |
| 24 | #include <linux/module.h> |
| 25 | #include <linux/sysctl.h> |
| 26 | #include <linux/workqueue.h> |
| 27 | #include <net/tcp.h> |
| 28 | #include <net/inet_common.h> |
| 29 | #include <net/xfrm.h> |
| 30 | |
| 31 | #ifdef CONFIG_SYSCTL |
| 32 | #define SYNC_INIT 0 /* let the user enable it */ |
| 33 | #else |
| 34 | #define SYNC_INIT 1 |
| 35 | #endif |
| 36 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 37 | int sysctl_tcp_syncookies = SYNC_INIT; |
| 38 | int sysctl_tcp_abort_on_overflow; |
| 39 | |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 40 | struct inet_timewait_death_row tcp_death_row = { |
| 41 | .sysctl_max_tw_buckets = NR_FILE * 2, |
| 42 | .period = TCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS, |
Ingo Molnar | e4d9191 | 2006-07-03 00:24:34 -0700 | [diff] [blame] | 43 | .death_lock = __SPIN_LOCK_UNLOCKED(tcp_death_row.death_lock), |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 44 | .hashinfo = &tcp_hashinfo, |
| 45 | .tw_timer = TIMER_INITIALIZER(inet_twdr_hangman, 0, |
| 46 | (unsigned long)&tcp_death_row), |
| 47 | .twkill_work = __WORK_INITIALIZER(tcp_death_row.twkill_work, |
| 48 | inet_twdr_twkill_work, |
| 49 | &tcp_death_row), |
| 50 | /* Short-time timewait calendar */ |
| 51 | |
| 52 | .twcal_hand = -1, |
| 53 | .twcal_timer = TIMER_INITIALIZER(inet_twdr_twcal_tick, 0, |
| 54 | (unsigned long)&tcp_death_row), |
| 55 | }; |
| 56 | |
| 57 | EXPORT_SYMBOL_GPL(tcp_death_row); |
| 58 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 59 | static __inline__ int tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win) |
| 60 | { |
| 61 | if (seq == s_win) |
| 62 | return 1; |
| 63 | if (after(end_seq, s_win) && before(seq, e_win)) |
| 64 | return 1; |
| 65 | return (seq == e_win && seq == end_seq); |
| 66 | } |
| 67 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 68 | /* |
| 69 | * * Main purpose of TIME-WAIT state is to close connection gracefully, |
| 70 | * when one of ends sits in LAST-ACK or CLOSING retransmitting FIN |
| 71 | * (and, probably, tail of data) and one or more our ACKs are lost. |
| 72 | * * What is TIME-WAIT timeout? It is associated with maximal packet |
| 73 | * lifetime in the internet, which results in wrong conclusion, that |
| 74 | * it is set to catch "old duplicate segments" wandering out of their path. |
| 75 | * It is not quite correct. This timeout is calculated so that it exceeds |
| 76 | * maximal retransmission timeout enough to allow to lose one (or more) |
| 77 | * segments sent by peer and our ACKs. This time may be calculated from RTO. |
| 78 | * * When TIME-WAIT socket receives RST, it means that another end |
| 79 | * finally closed and we are allowed to kill TIME-WAIT too. |
| 80 | * * Second purpose of TIME-WAIT is catching old duplicate segments. |
| 81 | * Well, certainly it is pure paranoia, but if we load TIME-WAIT |
| 82 | * with this semantics, we MUST NOT kill TIME-WAIT state with RSTs. |
| 83 | * * If we invented some more clever way to catch duplicates |
| 84 | * (f.e. based on PAWS), we could truncate TIME-WAIT to several RTOs. |
| 85 | * |
| 86 | * The algorithm below is based on FORMAL INTERPRETATION of RFCs. |
| 87 | * When you compare it to RFCs, please, read section SEGMENT ARRIVES |
| 88 | * from the very beginning. |
| 89 | * |
| 90 | * NOTE. With recycling (and later with fin-wait-2) TW bucket |
| 91 | * is _not_ stateless. It means, that strictly speaking we must |
| 92 | * spinlock it. I do not want! Well, probability of misbehaviour |
| 93 | * is ridiculously low and, seems, we could use some mb() tricks |
| 94 | * to avoid misread sequence numbers, states etc. --ANK |
| 95 | */ |
| 96 | enum tcp_tw_status |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 97 | tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, |
| 98 | const struct tcphdr *th) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 99 | { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 100 | struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | struct tcp_options_received tmp_opt; |
| 102 | int paws_reject = 0; |
| 103 | |
| 104 | tmp_opt.saw_tstamp = 0; |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 105 | if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 106 | tcp_parse_options(skb, &tmp_opt, 0); |
| 107 | |
| 108 | if (tmp_opt.saw_tstamp) { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 109 | tmp_opt.ts_recent = tcptw->tw_ts_recent; |
| 110 | tmp_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 111 | paws_reject = tcp_paws_check(&tmp_opt, th->rst); |
| 112 | } |
| 113 | } |
| 114 | |
| 115 | if (tw->tw_substate == TCP_FIN_WAIT2) { |
| 116 | /* Just repeat all the checks of tcp_rcv_state_process() */ |
| 117 | |
| 118 | /* Out of window, send ACK */ |
| 119 | if (paws_reject || |
| 120 | !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] | 121 | tcptw->tw_rcv_nxt, |
| 122 | tcptw->tw_rcv_nxt + tcptw->tw_rcv_wnd)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 123 | return TCP_TW_ACK; |
| 124 | |
| 125 | if (th->rst) |
| 126 | goto kill; |
| 127 | |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 128 | 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] | 129 | goto kill_with_rst; |
| 130 | |
| 131 | /* Dup ACK? */ |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 132 | if (!after(TCP_SKB_CB(skb)->end_seq, tcptw->tw_rcv_nxt) || |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 133 | 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] | 134 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 135 | return TCP_TW_SUCCESS; |
| 136 | } |
| 137 | |
| 138 | /* New data or FIN. If new data arrive after half-duplex close, |
| 139 | * reset. |
| 140 | */ |
| 141 | if (!th->fin || |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 142 | TCP_SKB_CB(skb)->end_seq != tcptw->tw_rcv_nxt + 1) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 143 | kill_with_rst: |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 144 | inet_twsk_deschedule(tw, &tcp_death_row); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 145 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 146 | return TCP_TW_RST; |
| 147 | } |
| 148 | |
| 149 | /* FIN arrived, enter true time-wait state. */ |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 150 | tw->tw_substate = TCP_TIME_WAIT; |
| 151 | tcptw->tw_rcv_nxt = TCP_SKB_CB(skb)->end_seq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 152 | if (tmp_opt.saw_tstamp) { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 153 | tcptw->tw_ts_recent_stamp = xtime.tv_sec; |
| 154 | tcptw->tw_ts_recent = tmp_opt.rcv_tsval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 155 | } |
| 156 | |
| 157 | /* I am shamed, but failed to make it more elegant. |
| 158 | * Yes, it is direct reference to IP, which is impossible |
| 159 | * to generalize to IPv6. Taking into account that IPv6 |
Stephen Hemminger | caa20d9a | 2005-11-10 17:13:47 -0800 | [diff] [blame] | 160 | * do not understand recycling in any case, it not |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 161 | * a big problem in practice. --ANK */ |
| 162 | if (tw->tw_family == AF_INET && |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 163 | tcp_death_row.sysctl_tw_recycle && tcptw->tw_ts_recent_stamp && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 164 | tcp_v4_tw_remember_stamp(tw)) |
Arnaldo Carvalho de Melo | 696ab2d | 2005-08-09 20:45:03 -0700 | [diff] [blame] | 165 | inet_twsk_schedule(tw, &tcp_death_row, tw->tw_timeout, |
| 166 | TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 167 | else |
Arnaldo Carvalho de Melo | 696ab2d | 2005-08-09 20:45:03 -0700 | [diff] [blame] | 168 | inet_twsk_schedule(tw, &tcp_death_row, TCP_TIMEWAIT_LEN, |
| 169 | TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 170 | return TCP_TW_ACK; |
| 171 | } |
| 172 | |
| 173 | /* |
| 174 | * Now real TIME-WAIT state. |
| 175 | * |
| 176 | * RFC 1122: |
| 177 | * "When a connection is [...] on TIME-WAIT state [...] |
| 178 | * [a TCP] MAY accept a new SYN from the remote TCP to |
| 179 | * reopen the connection directly, if it: |
| 180 | * |
| 181 | * (1) assigns its initial sequence number for the new |
| 182 | * connection to be larger than the largest sequence |
| 183 | * number it used on the previous connection incarnation, |
| 184 | * and |
| 185 | * |
| 186 | * (2) returns to TIME-WAIT state if the SYN turns out |
| 187 | * to be an old duplicate". |
| 188 | */ |
| 189 | |
| 190 | if (!paws_reject && |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 191 | (TCP_SKB_CB(skb)->seq == tcptw->tw_rcv_nxt && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 192 | (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq || th->rst))) { |
| 193 | /* In window segment, it may be only reset or bare ack. */ |
| 194 | |
| 195 | if (th->rst) { |
Stephen Hemminger | caa20d9a | 2005-11-10 17:13:47 -0800 | [diff] [blame] | 196 | /* This is TIME_WAIT assassination, in two flavors. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 197 | * Oh well... nobody has a sufficient solution to this |
| 198 | * protocol bug yet. |
| 199 | */ |
| 200 | if (sysctl_tcp_rfc1337 == 0) { |
| 201 | kill: |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 202 | inet_twsk_deschedule(tw, &tcp_death_row); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 203 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 204 | return TCP_TW_SUCCESS; |
| 205 | } |
| 206 | } |
Arnaldo Carvalho de Melo | 696ab2d | 2005-08-09 20:45:03 -0700 | [diff] [blame] | 207 | inet_twsk_schedule(tw, &tcp_death_row, TCP_TIMEWAIT_LEN, |
| 208 | TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 209 | |
| 210 | if (tmp_opt.saw_tstamp) { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 211 | tcptw->tw_ts_recent = tmp_opt.rcv_tsval; |
| 212 | tcptw->tw_ts_recent_stamp = xtime.tv_sec; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 213 | } |
| 214 | |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 215 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 216 | return TCP_TW_SUCCESS; |
| 217 | } |
| 218 | |
| 219 | /* Out of window segment. |
| 220 | |
| 221 | All the segments are ACKed immediately. |
| 222 | |
| 223 | The only exception is new SYN. We accept it, if it is |
| 224 | not old duplicate and we are not in danger to be killed |
| 225 | by delayed old duplicates. RFC check is that it has |
| 226 | newer sequence number works at rates <40Mbit/sec. |
| 227 | However, if paws works, it is reliable AND even more, |
| 228 | we even may relax silly seq space cutoff. |
| 229 | |
| 230 | RED-PEN: we violate main RFC requirement, if this SYN will appear |
| 231 | old duplicate (i.e. we receive RST in reply to SYN-ACK), |
| 232 | we must return socket to time-wait state. It is not good, |
| 233 | but not fatal yet. |
| 234 | */ |
| 235 | |
| 236 | if (th->syn && !th->rst && !th->ack && !paws_reject && |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 237 | (after(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt) || |
| 238 | (tmp_opt.saw_tstamp && |
| 239 | (s32)(tcptw->tw_ts_recent - tmp_opt.rcv_tsval) < 0))) { |
| 240 | u32 isn = tcptw->tw_snd_nxt + 65535 + 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 241 | if (isn == 0) |
| 242 | isn++; |
| 243 | TCP_SKB_CB(skb)->when = isn; |
| 244 | return TCP_TW_SYN; |
| 245 | } |
| 246 | |
| 247 | if (paws_reject) |
| 248 | NET_INC_STATS_BH(LINUX_MIB_PAWSESTABREJECTED); |
| 249 | |
| 250 | if(!th->rst) { |
| 251 | /* In this case we must reset the TIMEWAIT timer. |
| 252 | * |
| 253 | * If it is ACKless SYN it may be both old duplicate |
| 254 | * and new good SYN with random sequence number <rcv_nxt. |
| 255 | * Do not reschedule in the last case. |
| 256 | */ |
| 257 | if (paws_reject || th->ack) |
Arnaldo Carvalho de Melo | 696ab2d | 2005-08-09 20:45:03 -0700 | [diff] [blame] | 258 | inet_twsk_schedule(tw, &tcp_death_row, TCP_TIMEWAIT_LEN, |
| 259 | TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 260 | |
| 261 | /* Send ACK. Note, we do not put the bucket, |
| 262 | * it will be released by caller. |
| 263 | */ |
| 264 | return TCP_TW_ACK; |
| 265 | } |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 266 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 267 | return TCP_TW_SUCCESS; |
| 268 | } |
| 269 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 270 | /* |
| 271 | * Move a socket to time-wait or dead fin-wait-2 state. |
| 272 | */ |
| 273 | void tcp_time_wait(struct sock *sk, int state, int timeo) |
| 274 | { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 275 | struct inet_timewait_sock *tw = NULL; |
Arnaldo Carvalho de Melo | 8292a17 | 2005-12-13 23:15:52 -0800 | [diff] [blame] | 276 | const struct inet_connection_sock *icsk = inet_csk(sk); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 277 | const struct tcp_sock *tp = tcp_sk(sk); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 278 | int recycle_ok = 0; |
| 279 | |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 280 | if (tcp_death_row.sysctl_tw_recycle && tp->rx_opt.ts_recent_stamp) |
Arnaldo Carvalho de Melo | 8292a17 | 2005-12-13 23:15:52 -0800 | [diff] [blame] | 281 | recycle_ok = icsk->icsk_af_ops->remember_stamp(sk); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 282 | |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 283 | if (tcp_death_row.tw_count < tcp_death_row.sysctl_max_tw_buckets) |
Arnaldo Carvalho de Melo | c676270 | 2005-08-09 20:09:59 -0700 | [diff] [blame] | 284 | tw = inet_twsk_alloc(sk, state); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 285 | |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 286 | if (tw != NULL) { |
| 287 | struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 288 | const int rto = (icsk->icsk_rto << 2) - (icsk->icsk_rto >> 1); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 289 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 290 | tw->tw_rcv_wscale = tp->rx_opt.rcv_wscale; |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 291 | tcptw->tw_rcv_nxt = tp->rcv_nxt; |
| 292 | tcptw->tw_snd_nxt = tp->snd_nxt; |
| 293 | tcptw->tw_rcv_wnd = tcp_receive_window(tp); |
| 294 | tcptw->tw_ts_recent = tp->rx_opt.ts_recent; |
| 295 | tcptw->tw_ts_recent_stamp = tp->rx_opt.ts_recent_stamp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 296 | |
| 297 | #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE) |
| 298 | if (tw->tw_family == PF_INET6) { |
| 299 | struct ipv6_pinfo *np = inet6_sk(sk); |
Arnaldo Carvalho de Melo | 0fa1a53 | 2005-12-13 23:23:09 -0800 | [diff] [blame] | 300 | struct inet6_timewait_sock *tw6; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 301 | |
Arnaldo Carvalho de Melo | 0fa1a53 | 2005-12-13 23:23:09 -0800 | [diff] [blame] | 302 | tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot); |
| 303 | tw6 = inet6_twsk((struct sock *)tw); |
| 304 | ipv6_addr_copy(&tw6->tw_v6_daddr, &np->daddr); |
| 305 | ipv6_addr_copy(&tw6->tw_v6_rcv_saddr, &np->rcv_saddr); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 306 | tw->tw_ipv6only = np->ipv6only; |
Arnaldo Carvalho de Melo | c676270 | 2005-08-09 20:09:59 -0700 | [diff] [blame] | 307 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 308 | #endif |
| 309 | /* Linkage updates. */ |
Arnaldo Carvalho de Melo | e48c414 | 2005-08-09 20:09:46 -0700 | [diff] [blame] | 310 | __inet_twsk_hashdance(tw, sk, &tcp_hashinfo); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 311 | |
| 312 | /* Get the TIME_WAIT timeout firing. */ |
| 313 | if (timeo < rto) |
| 314 | timeo = rto; |
| 315 | |
| 316 | if (recycle_ok) { |
| 317 | tw->tw_timeout = rto; |
| 318 | } else { |
| 319 | tw->tw_timeout = TCP_TIMEWAIT_LEN; |
| 320 | if (state == TCP_TIME_WAIT) |
| 321 | timeo = TCP_TIMEWAIT_LEN; |
| 322 | } |
| 323 | |
Arnaldo Carvalho de Melo | 696ab2d | 2005-08-09 20:45:03 -0700 | [diff] [blame] | 324 | inet_twsk_schedule(tw, &tcp_death_row, timeo, |
| 325 | TCP_TIMEWAIT_LEN); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 326 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 327 | } else { |
| 328 | /* Sorry, if we're out of memory, just CLOSE this |
| 329 | * socket up. We've got bigger problems than |
| 330 | * non-graceful socket closings. |
| 331 | */ |
| 332 | if (net_ratelimit()) |
| 333 | printk(KERN_INFO "TCP: time wait bucket table overflow\n"); |
| 334 | } |
| 335 | |
| 336 | tcp_update_metrics(sk); |
| 337 | tcp_done(sk); |
| 338 | } |
| 339 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 340 | /* This is not only more efficient than what we used to do, it eliminates |
| 341 | * a lot of code duplication between IPv4/IPv6 SYN recv processing. -DaveM |
| 342 | * |
| 343 | * Actually, we could lots of memory writes here. tp of listening |
| 344 | * socket contains all necessary default parameters. |
| 345 | */ |
Arnaldo Carvalho de Melo | 60236fd | 2005-06-18 22:47:21 -0700 | [diff] [blame] | 346 | 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] | 347 | { |
Arnaldo Carvalho de Melo | 9f1d260 | 2005-08-09 20:11:24 -0700 | [diff] [blame] | 348 | struct sock *newsk = inet_csk_clone(sk, req, GFP_ATOMIC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 349 | |
Arnaldo Carvalho de Melo | 87d11ce | 2005-08-09 20:10:12 -0700 | [diff] [blame] | 350 | if (newsk != NULL) { |
Arnaldo Carvalho de Melo | 9f1d260 | 2005-08-09 20:11:24 -0700 | [diff] [blame] | 351 | const struct inet_request_sock *ireq = inet_rsk(req); |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 352 | struct tcp_request_sock *treq = tcp_rsk(req); |
Arnaldo Carvalho de Melo | 9f1d260 | 2005-08-09 20:11:24 -0700 | [diff] [blame] | 353 | struct inet_connection_sock *newicsk = inet_csk(sk); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 354 | struct tcp_sock *newtp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 355 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 356 | /* Now setup tcp_sock */ |
| 357 | newtp = tcp_sk(newsk); |
| 358 | newtp->pred_flags = 0; |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 359 | newtp->rcv_nxt = treq->rcv_isn + 1; |
Arnaldo Carvalho de Melo | 87d11ce | 2005-08-09 20:10:12 -0700 | [diff] [blame] | 360 | newtp->snd_nxt = newtp->snd_una = newtp->snd_sml = treq->snt_isn + 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 361 | |
| 362 | tcp_prequeue_init(newtp); |
| 363 | |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 364 | tcp_init_wl(newtp, treq->snt_isn, treq->rcv_isn); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 365 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 366 | newtp->srtt = 0; |
| 367 | newtp->mdev = TCP_TIMEOUT_INIT; |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 368 | newicsk->icsk_rto = TCP_TIMEOUT_INIT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 369 | |
| 370 | newtp->packets_out = 0; |
| 371 | newtp->left_out = 0; |
| 372 | newtp->retrans_out = 0; |
| 373 | newtp->sacked_out = 0; |
| 374 | newtp->fackets_out = 0; |
| 375 | newtp->snd_ssthresh = 0x7fffffff; |
| 376 | |
| 377 | /* So many TCP implementations out there (incorrectly) count the |
| 378 | * initial SYN frame in their delayed-ACK and congestion control |
| 379 | * algorithms that we must have the following bandaid to talk |
| 380 | * efficiently to them. -DaveM |
| 381 | */ |
| 382 | newtp->snd_cwnd = 2; |
| 383 | newtp->snd_cwnd_cnt = 0; |
Stephen Hemminger | 9772efb | 2005-11-10 17:09:53 -0800 | [diff] [blame] | 384 | newtp->bytes_acked = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 385 | |
| 386 | newtp->frto_counter = 0; |
| 387 | newtp->frto_highmark = 0; |
| 388 | |
Stephen Hemminger | 7957aed | 2005-09-21 00:19:46 -0700 | [diff] [blame] | 389 | newicsk->icsk_ca_ops = &tcp_init_congestion_ops; |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 390 | |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 391 | tcp_set_ca_state(newsk, TCP_CA_Open); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 392 | tcp_init_xmit_timers(newsk); |
| 393 | skb_queue_head_init(&newtp->out_of_order_queue); |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 394 | newtp->rcv_wup = treq->rcv_isn + 1; |
| 395 | newtp->write_seq = treq->snt_isn + 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 396 | newtp->pushed_seq = newtp->write_seq; |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 397 | newtp->copied_seq = treq->rcv_isn + 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 398 | |
| 399 | newtp->rx_opt.saw_tstamp = 0; |
| 400 | |
| 401 | newtp->rx_opt.dsack = 0; |
| 402 | newtp->rx_opt.eff_sacks = 0; |
| 403 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 404 | newtp->rx_opt.num_sacks = 0; |
| 405 | newtp->urg_data = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 406 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 407 | if (sock_flag(newsk, SOCK_KEEPOPEN)) |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 408 | inet_csk_reset_keepalive_timer(newsk, |
| 409 | keepalive_time_when(newtp)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 410 | |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 411 | newtp->rx_opt.tstamp_ok = ireq->tstamp_ok; |
| 412 | if((newtp->rx_opt.sack_ok = ireq->sack_ok) != 0) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 413 | if (sysctl_tcp_fack) |
| 414 | newtp->rx_opt.sack_ok |= 2; |
| 415 | } |
| 416 | newtp->window_clamp = req->window_clamp; |
| 417 | newtp->rcv_ssthresh = req->rcv_wnd; |
| 418 | newtp->rcv_wnd = req->rcv_wnd; |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 419 | newtp->rx_opt.wscale_ok = ireq->wscale_ok; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 420 | if (newtp->rx_opt.wscale_ok) { |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 421 | newtp->rx_opt.snd_wscale = ireq->snd_wscale; |
| 422 | newtp->rx_opt.rcv_wscale = ireq->rcv_wscale; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 423 | } else { |
| 424 | newtp->rx_opt.snd_wscale = newtp->rx_opt.rcv_wscale = 0; |
| 425 | newtp->window_clamp = min(newtp->window_clamp, 65535U); |
| 426 | } |
| 427 | newtp->snd_wnd = ntohs(skb->h.th->window) << newtp->rx_opt.snd_wscale; |
| 428 | newtp->max_window = newtp->snd_wnd; |
| 429 | |
| 430 | if (newtp->rx_opt.tstamp_ok) { |
| 431 | newtp->rx_opt.ts_recent = req->ts_recent; |
| 432 | newtp->rx_opt.ts_recent_stamp = xtime.tv_sec; |
| 433 | newtp->tcp_header_len = sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED; |
| 434 | } else { |
| 435 | newtp->rx_opt.ts_recent_stamp = 0; |
| 436 | newtp->tcp_header_len = sizeof(struct tcphdr); |
| 437 | } |
| 438 | if (skb->len >= TCP_MIN_RCVMSS+newtp->tcp_header_len) |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 439 | newicsk->icsk_ack.last_seg_size = skb->len - newtp->tcp_header_len; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 440 | newtp->rx_opt.mss_clamp = req->mss; |
| 441 | TCP_ECN_openreq_child(newtp, req); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 442 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 443 | TCP_INC_STATS_BH(TCP_MIB_PASSIVEOPENS); |
| 444 | } |
| 445 | return newsk; |
| 446 | } |
| 447 | |
| 448 | /* |
| 449 | * Process an incoming packet for SYN_RECV sockets represented |
Arnaldo Carvalho de Melo | 60236fd | 2005-06-18 22:47:21 -0700 | [diff] [blame] | 450 | * as a request_sock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 451 | */ |
| 452 | |
| 453 | 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] | 454 | struct request_sock *req, |
| 455 | struct request_sock **prev) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 456 | { |
| 457 | struct tcphdr *th = skb->h.th; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 458 | u32 flg = tcp_flag_word(th) & (TCP_FLAG_RST|TCP_FLAG_SYN|TCP_FLAG_ACK); |
| 459 | int paws_reject = 0; |
| 460 | struct tcp_options_received tmp_opt; |
| 461 | struct sock *child; |
| 462 | |
| 463 | tmp_opt.saw_tstamp = 0; |
| 464 | if (th->doff > (sizeof(struct tcphdr)>>2)) { |
| 465 | tcp_parse_options(skb, &tmp_opt, 0); |
| 466 | |
| 467 | if (tmp_opt.saw_tstamp) { |
| 468 | tmp_opt.ts_recent = req->ts_recent; |
| 469 | /* We do not store true stamp, but it is not required, |
| 470 | * it can be estimated (approximately) |
| 471 | * from another data. |
| 472 | */ |
| 473 | tmp_opt.ts_recent_stamp = xtime.tv_sec - ((TCP_TIMEOUT_INIT/HZ)<<req->retrans); |
| 474 | paws_reject = tcp_paws_check(&tmp_opt, th->rst); |
| 475 | } |
| 476 | } |
| 477 | |
| 478 | /* Check for pure retransmitted SYN. */ |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 479 | if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 480 | flg == TCP_FLAG_SYN && |
| 481 | !paws_reject) { |
| 482 | /* |
| 483 | * RFC793 draws (Incorrectly! It was fixed in RFC1122) |
| 484 | * this case on figure 6 and figure 8, but formal |
| 485 | * protocol description says NOTHING. |
| 486 | * To be more exact, it says that we should send ACK, |
| 487 | * because this segment (at least, if it has no data) |
| 488 | * is out of window. |
| 489 | * |
| 490 | * CONCLUSION: RFC793 (even with RFC1122) DOES NOT |
| 491 | * describe SYN-RECV state. All the description |
| 492 | * is wrong, we cannot believe to it and should |
| 493 | * rely only on common sense and implementation |
| 494 | * experience. |
| 495 | * |
| 496 | * Enforce "SYN-ACK" according to figure 8, figure 6 |
| 497 | * of RFC793, fixed by RFC1122. |
| 498 | */ |
Arnaldo Carvalho de Melo | 60236fd | 2005-06-18 22:47:21 -0700 | [diff] [blame] | 499 | req->rsk_ops->rtx_syn_ack(sk, req, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 500 | return NULL; |
| 501 | } |
| 502 | |
| 503 | /* Further reproduces section "SEGMENT ARRIVES" |
| 504 | for state SYN-RECEIVED of RFC793. |
| 505 | It is broken, however, it does not work only |
| 506 | when SYNs are crossed. |
| 507 | |
| 508 | You would think that SYN crossing is impossible here, since |
| 509 | we should have a SYN_SENT socket (from connect()) on our end, |
| 510 | but this is not true if the crossed SYNs were sent to both |
| 511 | ends by a malicious third party. We must defend against this, |
| 512 | and to do that we first verify the ACK (as per RFC793, page |
| 513 | 36) and reset if it is invalid. Is this a true full defense? |
| 514 | To convince ourselves, let us consider a way in which the ACK |
| 515 | test can still pass in this 'malicious crossed SYNs' case. |
| 516 | Malicious sender sends identical SYNs (and thus identical sequence |
| 517 | numbers) to both A and B: |
| 518 | |
| 519 | A: gets SYN, seq=7 |
| 520 | B: gets SYN, seq=7 |
| 521 | |
| 522 | By our good fortune, both A and B select the same initial |
| 523 | send sequence number of seven :-) |
| 524 | |
| 525 | A: sends SYN|ACK, seq=7, ack_seq=8 |
| 526 | B: sends SYN|ACK, seq=7, ack_seq=8 |
| 527 | |
| 528 | So we are now A eating this SYN|ACK, ACK test passes. So |
| 529 | does sequence test, SYN is truncated, and thus we consider |
| 530 | it a bare ACK. |
| 531 | |
Arnaldo Carvalho de Melo | 295f732 | 2005-08-09 20:11:56 -0700 | [diff] [blame] | 532 | If icsk->icsk_accept_queue.rskq_defer_accept, we silently drop this |
| 533 | bare ACK. Otherwise, we create an established connection. Both |
| 534 | ends (listening sockets) accept the new incoming connection and try |
| 535 | to talk to each other. 8-) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 536 | |
| 537 | Note: This case is both harmless, and rare. Possibility is about the |
| 538 | same as us discovering intelligent life on another plant tomorrow. |
| 539 | |
| 540 | But generally, we should (RFC lies!) to accept ACK |
| 541 | from SYNACK both here and in tcp_rcv_state_process(). |
| 542 | tcp_rcv_state_process() does not, hence, we do not too. |
| 543 | |
| 544 | Note that the case is absolutely generic: |
| 545 | we cannot optimize anything here without |
| 546 | violating protocol. All the checks must be made |
| 547 | before attempt to create socket. |
| 548 | */ |
| 549 | |
| 550 | /* RFC793 page 36: "If the connection is in any non-synchronized state ... |
| 551 | * and the incoming segment acknowledges something not yet |
Stephen Hemminger | caa20d9a | 2005-11-10 17:13:47 -0800 | [diff] [blame] | 552 | * sent (the segment carries an unacceptable ACK) ... |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 553 | * a reset is sent." |
| 554 | * |
| 555 | * Invalid ACK: reset will be sent by listening socket |
| 556 | */ |
| 557 | if ((flg & TCP_FLAG_ACK) && |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 558 | (TCP_SKB_CB(skb)->ack_seq != tcp_rsk(req)->snt_isn + 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 559 | return sk; |
| 560 | |
| 561 | /* Also, it would be not so bad idea to check rcv_tsecr, which |
| 562 | * is essentially ACK extension and too early or too late values |
| 563 | * should cause reset in unsynchronized states. |
| 564 | */ |
| 565 | |
| 566 | /* RFC793: "first check sequence number". */ |
| 567 | |
| 568 | if (paws_reject || !tcp_in_window(TCP_SKB_CB(skb)->seq, TCP_SKB_CB(skb)->end_seq, |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 569 | tcp_rsk(req)->rcv_isn + 1, tcp_rsk(req)->rcv_isn + 1 + req->rcv_wnd)) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 570 | /* Out of window: send ACK and drop. */ |
| 571 | if (!(flg & TCP_FLAG_RST)) |
Arnaldo Carvalho de Melo | 60236fd | 2005-06-18 22:47:21 -0700 | [diff] [blame] | 572 | req->rsk_ops->send_ack(skb, req); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 573 | if (paws_reject) |
| 574 | NET_INC_STATS_BH(LINUX_MIB_PAWSESTABREJECTED); |
| 575 | return NULL; |
| 576 | } |
| 577 | |
| 578 | /* In sequence, PAWS is OK. */ |
| 579 | |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 580 | if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_isn + 1)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 581 | req->ts_recent = tmp_opt.rcv_tsval; |
| 582 | |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 583 | if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 584 | /* Truncate SYN, it is out of window starting |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 585 | at tcp_rsk(req)->rcv_isn + 1. */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 586 | flg &= ~TCP_FLAG_SYN; |
| 587 | } |
| 588 | |
| 589 | /* RFC793: "second check the RST bit" and |
| 590 | * "fourth, check the SYN bit" |
| 591 | */ |
| 592 | if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN)) |
| 593 | goto embryonic_reset; |
| 594 | |
| 595 | /* ACK sequence verified above, just make sure ACK is |
| 596 | * set. If ACK not set, just silently drop the packet. |
| 597 | */ |
| 598 | if (!(flg & TCP_FLAG_ACK)) |
| 599 | return NULL; |
| 600 | |
| 601 | /* If TCP_DEFER_ACCEPT is set, drop bare ACK. */ |
Arnaldo Carvalho de Melo | 295f732 | 2005-08-09 20:11:56 -0700 | [diff] [blame] | 602 | if (inet_csk(sk)->icsk_accept_queue.rskq_defer_accept && |
| 603 | TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) { |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 604 | inet_rsk(req)->acked = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 605 | return NULL; |
| 606 | } |
| 607 | |
| 608 | /* OK, ACK is valid, create big socket and |
| 609 | * feed this segment to it. It will repeat all |
| 610 | * the tests. THIS SEGMENT MUST MOVE SOCKET TO |
| 611 | * ESTABLISHED STATE. If it will be dropped after |
| 612 | * socket is created, wait for troubles. |
| 613 | */ |
Arnaldo Carvalho de Melo | 8292a17 | 2005-12-13 23:15:52 -0800 | [diff] [blame] | 614 | child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, |
| 615 | req, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 616 | if (child == NULL) |
| 617 | goto listen_overflow; |
| 618 | |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 619 | inet_csk_reqsk_queue_unlink(sk, req, prev); |
| 620 | inet_csk_reqsk_queue_removed(sk, req); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 621 | |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 622 | inet_csk_reqsk_queue_add(sk, req, child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 623 | return child; |
| 624 | |
| 625 | listen_overflow: |
| 626 | if (!sysctl_tcp_abort_on_overflow) { |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 627 | inet_rsk(req)->acked = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 628 | return NULL; |
| 629 | } |
| 630 | |
| 631 | embryonic_reset: |
| 632 | NET_INC_STATS_BH(LINUX_MIB_EMBRYONICRSTS); |
| 633 | if (!(flg & TCP_FLAG_RST)) |
Arnaldo Carvalho de Melo | 60236fd | 2005-06-18 22:47:21 -0700 | [diff] [blame] | 634 | req->rsk_ops->send_reset(skb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 635 | |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 636 | inet_csk_reqsk_queue_drop(sk, req, prev); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 637 | return NULL; |
| 638 | } |
| 639 | |
| 640 | /* |
| 641 | * Queue segment on the new socket if the new socket is active, |
| 642 | * otherwise we just shortcircuit this and continue with |
| 643 | * the new socket. |
| 644 | */ |
| 645 | |
| 646 | int tcp_child_process(struct sock *parent, struct sock *child, |
| 647 | struct sk_buff *skb) |
| 648 | { |
| 649 | int ret = 0; |
| 650 | int state = child->sk_state; |
| 651 | |
| 652 | if (!sock_owned_by_user(child)) { |
| 653 | ret = tcp_rcv_state_process(child, skb, skb->h.th, skb->len); |
| 654 | |
| 655 | /* Wakeup parent, send SIGIO */ |
| 656 | if (state == TCP_SYN_RECV && child->sk_state != state) |
| 657 | parent->sk_data_ready(parent, 0); |
| 658 | } else { |
| 659 | /* Alas, it is possible again, because we do lookup |
| 660 | * in main socket hash table and lock on listening |
| 661 | * socket does not protect us more. |
| 662 | */ |
| 663 | sk_add_backlog(child, skb); |
| 664 | } |
| 665 | |
| 666 | bh_unlock_sock(child); |
| 667 | sock_put(child); |
| 668 | return ret; |
| 669 | } |
| 670 | |
| 671 | EXPORT_SYMBOL(tcp_check_req); |
| 672 | EXPORT_SYMBOL(tcp_child_process); |
| 673 | EXPORT_SYMBOL(tcp_create_openreq_child); |
| 674 | EXPORT_SYMBOL(tcp_timewait_state_process); |