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, |
| 37 | .period = TCP_TIMEWAIT_LEN / INET_TWDR_TWKILL_SLOTS, |
Ingo Molnar | e4d9191 | 2006-07-03 00:24:34 -0700 | [diff] [blame] | 38 | .death_lock = __SPIN_LOCK_UNLOCKED(tcp_death_row.death_lock), |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 39 | .hashinfo = &tcp_hashinfo, |
| 40 | .tw_timer = TIMER_INITIALIZER(inet_twdr_hangman, 0, |
| 41 | (unsigned long)&tcp_death_row), |
| 42 | .twkill_work = __WORK_INITIALIZER(tcp_death_row.twkill_work, |
David Howells | 65f27f3 | 2006-11-22 14:55:48 +0000 | [diff] [blame] | 43 | inet_twdr_twkill_work), |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 44 | /* Short-time timewait calendar */ |
| 45 | |
| 46 | .twcal_hand = -1, |
| 47 | .twcal_timer = TIMER_INITIALIZER(inet_twdr_twcal_tick, 0, |
| 48 | (unsigned long)&tcp_death_row), |
| 49 | }; |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 50 | EXPORT_SYMBOL_GPL(tcp_death_row); |
| 51 | |
David S. Miller | 3f419d2 | 2010-11-29 13:37:14 -0800 | [diff] [blame] | 52 | /* VJ's idea. Save last timestamp seen from this destination |
| 53 | * and hold it at least for normal timewait interval to use for duplicate |
| 54 | * segment detection in subsequent connections, before they enter synchronized |
| 55 | * state. |
| 56 | */ |
| 57 | |
| 58 | static int tcp_remember_stamp(struct sock *sk) |
| 59 | { |
| 60 | const struct inet_connection_sock *icsk = inet_csk(sk); |
| 61 | struct tcp_sock *tp = tcp_sk(sk); |
| 62 | struct inet_peer *peer; |
| 63 | bool release_it; |
| 64 | |
| 65 | peer = icsk->icsk_af_ops->get_peer(sk, &release_it); |
| 66 | if (peer) { |
| 67 | if ((s32)(peer->tcp_ts - tp->rx_opt.ts_recent) <= 0 || |
| 68 | ((u32)get_seconds() - peer->tcp_ts_stamp > TCP_PAWS_MSL && |
| 69 | peer->tcp_ts_stamp <= (u32)tp->rx_opt.ts_recent_stamp)) { |
| 70 | peer->tcp_ts_stamp = (u32)tp->rx_opt.ts_recent_stamp; |
| 71 | peer->tcp_ts = tp->rx_opt.ts_recent; |
| 72 | } |
| 73 | if (release_it) |
| 74 | inet_putpeer(peer); |
| 75 | return 1; |
| 76 | } |
| 77 | |
| 78 | return 0; |
| 79 | } |
| 80 | |
David S. Miller | ccb7c41 | 2010-12-01 18:09:13 -0800 | [diff] [blame] | 81 | static int tcp_tw_remember_stamp(struct inet_timewait_sock *tw) |
| 82 | { |
| 83 | struct sock *sk = (struct sock *) tw; |
| 84 | struct inet_peer *peer; |
| 85 | |
| 86 | peer = twsk_getpeer(sk); |
| 87 | if (peer) { |
| 88 | const struct tcp_timewait_sock *tcptw = tcp_twsk(sk); |
| 89 | |
| 90 | if ((s32)(peer->tcp_ts - tcptw->tw_ts_recent) <= 0 || |
| 91 | ((u32)get_seconds() - peer->tcp_ts_stamp > TCP_PAWS_MSL && |
| 92 | peer->tcp_ts_stamp <= (u32)tcptw->tw_ts_recent_stamp)) { |
| 93 | peer->tcp_ts_stamp = (u32)tcptw->tw_ts_recent_stamp; |
| 94 | peer->tcp_ts = tcptw->tw_ts_recent; |
| 95 | } |
| 96 | inet_putpeer(peer); |
| 97 | return 1; |
| 98 | } |
| 99 | return 0; |
| 100 | } |
| 101 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 102 | static __inline__ int tcp_in_window(u32 seq, u32 end_seq, u32 s_win, u32 e_win) |
| 103 | { |
| 104 | if (seq == s_win) |
| 105 | return 1; |
| 106 | if (after(end_seq, s_win) && before(seq, e_win)) |
| 107 | return 1; |
Eric Dumazet | a02cec2 | 2010-09-22 20:43:57 +0000 | [diff] [blame] | 108 | return seq == e_win && seq == end_seq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 109 | } |
| 110 | |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 111 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 112 | * * Main purpose of TIME-WAIT state is to close connection gracefully, |
| 113 | * when one of ends sits in LAST-ACK or CLOSING retransmitting FIN |
| 114 | * (and, probably, tail of data) and one or more our ACKs are lost. |
| 115 | * * What is TIME-WAIT timeout? It is associated with maximal packet |
| 116 | * lifetime in the internet, which results in wrong conclusion, that |
| 117 | * it is set to catch "old duplicate segments" wandering out of their path. |
| 118 | * It is not quite correct. This timeout is calculated so that it exceeds |
| 119 | * maximal retransmission timeout enough to allow to lose one (or more) |
| 120 | * segments sent by peer and our ACKs. This time may be calculated from RTO. |
| 121 | * * When TIME-WAIT socket receives RST, it means that another end |
| 122 | * finally closed and we are allowed to kill TIME-WAIT too. |
| 123 | * * Second purpose of TIME-WAIT is catching old duplicate segments. |
| 124 | * Well, certainly it is pure paranoia, but if we load TIME-WAIT |
| 125 | * with this semantics, we MUST NOT kill TIME-WAIT state with RSTs. |
| 126 | * * If we invented some more clever way to catch duplicates |
| 127 | * (f.e. based on PAWS), we could truncate TIME-WAIT to several RTOs. |
| 128 | * |
| 129 | * The algorithm below is based on FORMAL INTERPRETATION of RFCs. |
| 130 | * When you compare it to RFCs, please, read section SEGMENT ARRIVES |
| 131 | * from the very beginning. |
| 132 | * |
| 133 | * NOTE. With recycling (and later with fin-wait-2) TW bucket |
| 134 | * is _not_ stateless. It means, that strictly speaking we must |
| 135 | * spinlock it. I do not want! Well, probability of misbehaviour |
| 136 | * is ridiculously low and, seems, we could use some mb() tricks |
| 137 | * to avoid misread sequence numbers, states etc. --ANK |
| 138 | */ |
| 139 | enum tcp_tw_status |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 140 | tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, |
| 141 | const struct tcphdr *th) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 142 | { |
| 143 | struct tcp_options_received tmp_opt; |
Eric Dumazet | cf533ea | 2011-10-21 05:22:42 -0400 | [diff] [blame] | 144 | const u8 *hash_location; |
William Allen Simpson | 4957faade | 2009-12-02 18:25:27 +0000 | [diff] [blame] | 145 | struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 146 | int paws_reject = 0; |
| 147 | |
David S. Miller | bb5b7c1 | 2009-12-15 20:56:42 -0800 | [diff] [blame] | 148 | tmp_opt.saw_tstamp = 0; |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 149 | if (th->doff > (sizeof(*th) >> 2) && tcptw->tw_ts_recent_stamp) { |
David S. Miller | bb5b7c1 | 2009-12-15 20:56:42 -0800 | [diff] [blame] | 150 | tcp_parse_options(skb, &tmp_opt, &hash_location, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 151 | |
| 152 | if (tmp_opt.saw_tstamp) { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 153 | tmp_opt.ts_recent = tcptw->tw_ts_recent; |
| 154 | tmp_opt.ts_recent_stamp = tcptw->tw_ts_recent_stamp; |
Ilpo Järvinen | c887e6d | 2009-03-14 14:23:03 +0000 | [diff] [blame] | 155 | paws_reject = tcp_paws_reject(&tmp_opt, th->rst); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 156 | } |
| 157 | } |
| 158 | |
| 159 | if (tw->tw_substate == TCP_FIN_WAIT2) { |
| 160 | /* Just repeat all the checks of tcp_rcv_state_process() */ |
| 161 | |
| 162 | /* Out of window, send ACK */ |
| 163 | if (paws_reject || |
| 164 | !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] | 165 | tcptw->tw_rcv_nxt, |
| 166 | tcptw->tw_rcv_nxt + tcptw->tw_rcv_wnd)) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 167 | return TCP_TW_ACK; |
| 168 | |
| 169 | if (th->rst) |
| 170 | goto kill; |
| 171 | |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 172 | 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] | 173 | goto kill_with_rst; |
| 174 | |
| 175 | /* Dup ACK? */ |
Wei Yongjun | 1ac530b | 2009-06-24 22:29:31 +0000 | [diff] [blame] | 176 | if (!th->ack || |
| 177 | !after(TCP_SKB_CB(skb)->end_seq, tcptw->tw_rcv_nxt) || |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 178 | 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] | 179 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 180 | return TCP_TW_SUCCESS; |
| 181 | } |
| 182 | |
| 183 | /* New data or FIN. If new data arrive after half-duplex close, |
| 184 | * reset. |
| 185 | */ |
| 186 | if (!th->fin || |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 187 | TCP_SKB_CB(skb)->end_seq != tcptw->tw_rcv_nxt + 1) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 188 | kill_with_rst: |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 189 | inet_twsk_deschedule(tw, &tcp_death_row); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 190 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 191 | return TCP_TW_RST; |
| 192 | } |
| 193 | |
| 194 | /* FIN arrived, enter true time-wait state. */ |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 195 | tw->tw_substate = TCP_TIME_WAIT; |
| 196 | tcptw->tw_rcv_nxt = TCP_SKB_CB(skb)->end_seq; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 197 | if (tmp_opt.saw_tstamp) { |
James Morris | 9d729f7 | 2007-03-04 16:12:44 -0800 | [diff] [blame] | 198 | tcptw->tw_ts_recent_stamp = get_seconds(); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 199 | tcptw->tw_ts_recent = tmp_opt.rcv_tsval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 200 | } |
| 201 | |
David S. Miller | ccb7c41 | 2010-12-01 18:09:13 -0800 | [diff] [blame] | 202 | if (tcp_death_row.sysctl_tw_recycle && |
| 203 | tcptw->tw_ts_recent_stamp && |
| 204 | tcp_tw_remember_stamp(tw)) |
Arnaldo Carvalho de Melo | 696ab2d | 2005-08-09 20:45:03 -0700 | [diff] [blame] | 205 | inet_twsk_schedule(tw, &tcp_death_row, tw->tw_timeout, |
| 206 | TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 207 | else |
Arnaldo Carvalho de Melo | 696ab2d | 2005-08-09 20:45:03 -0700 | [diff] [blame] | 208 | inet_twsk_schedule(tw, &tcp_death_row, TCP_TIMEWAIT_LEN, |
| 209 | TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 210 | return TCP_TW_ACK; |
| 211 | } |
| 212 | |
| 213 | /* |
| 214 | * Now real TIME-WAIT state. |
| 215 | * |
| 216 | * RFC 1122: |
| 217 | * "When a connection is [...] on TIME-WAIT state [...] |
| 218 | * [a TCP] MAY accept a new SYN from the remote TCP to |
| 219 | * reopen the connection directly, if it: |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 220 | * |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 221 | * (1) assigns its initial sequence number for the new |
| 222 | * connection to be larger than the largest sequence |
| 223 | * number it used on the previous connection incarnation, |
| 224 | * and |
| 225 | * |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 226 | * (2) returns to TIME-WAIT state if the SYN turns out |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 227 | * to be an old duplicate". |
| 228 | */ |
| 229 | |
| 230 | if (!paws_reject && |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 231 | (TCP_SKB_CB(skb)->seq == tcptw->tw_rcv_nxt && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 232 | (TCP_SKB_CB(skb)->seq == TCP_SKB_CB(skb)->end_seq || th->rst))) { |
| 233 | /* In window segment, it may be only reset or bare ack. */ |
| 234 | |
| 235 | if (th->rst) { |
Stephen Hemminger | caa20d9a | 2005-11-10 17:13:47 -0800 | [diff] [blame] | 236 | /* This is TIME_WAIT assassination, in two flavors. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 237 | * Oh well... nobody has a sufficient solution to this |
| 238 | * protocol bug yet. |
| 239 | */ |
| 240 | if (sysctl_tcp_rfc1337 == 0) { |
| 241 | kill: |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 242 | inet_twsk_deschedule(tw, &tcp_death_row); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 243 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 244 | return TCP_TW_SUCCESS; |
| 245 | } |
| 246 | } |
Arnaldo Carvalho de Melo | 696ab2d | 2005-08-09 20:45:03 -0700 | [diff] [blame] | 247 | inet_twsk_schedule(tw, &tcp_death_row, TCP_TIMEWAIT_LEN, |
| 248 | TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 249 | |
| 250 | if (tmp_opt.saw_tstamp) { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 251 | tcptw->tw_ts_recent = tmp_opt.rcv_tsval; |
James Morris | 9d729f7 | 2007-03-04 16:12:44 -0800 | [diff] [blame] | 252 | tcptw->tw_ts_recent_stamp = get_seconds(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 253 | } |
| 254 | |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 255 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 256 | return TCP_TW_SUCCESS; |
| 257 | } |
| 258 | |
| 259 | /* Out of window segment. |
| 260 | |
| 261 | All the segments are ACKed immediately. |
| 262 | |
| 263 | The only exception is new SYN. We accept it, if it is |
| 264 | not old duplicate and we are not in danger to be killed |
| 265 | by delayed old duplicates. RFC check is that it has |
| 266 | newer sequence number works at rates <40Mbit/sec. |
| 267 | However, if paws works, it is reliable AND even more, |
| 268 | we even may relax silly seq space cutoff. |
| 269 | |
| 270 | RED-PEN: we violate main RFC requirement, if this SYN will appear |
| 271 | old duplicate (i.e. we receive RST in reply to SYN-ACK), |
| 272 | we must return socket to time-wait state. It is not good, |
| 273 | but not fatal yet. |
| 274 | */ |
| 275 | |
| 276 | if (th->syn && !th->rst && !th->ack && !paws_reject && |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 277 | (after(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt) || |
| 278 | (tmp_opt.saw_tstamp && |
| 279 | (s32)(tcptw->tw_ts_recent - tmp_opt.rcv_tsval) < 0))) { |
| 280 | u32 isn = tcptw->tw_snd_nxt + 65535 + 2; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 281 | if (isn == 0) |
| 282 | isn++; |
| 283 | TCP_SKB_CB(skb)->when = isn; |
| 284 | return TCP_TW_SYN; |
| 285 | } |
| 286 | |
| 287 | if (paws_reject) |
Pavel Emelyanov | de0744a | 2008-07-16 20:31:16 -0700 | [diff] [blame] | 288 | NET_INC_STATS_BH(twsk_net(tw), LINUX_MIB_PAWSESTABREJECTED); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 289 | |
Stephen Hemminger | 2de979b | 2007-03-08 20:45:19 -0800 | [diff] [blame] | 290 | if (!th->rst) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 291 | /* In this case we must reset the TIMEWAIT timer. |
| 292 | * |
| 293 | * If it is ACKless SYN it may be both old duplicate |
| 294 | * and new good SYN with random sequence number <rcv_nxt. |
| 295 | * Do not reschedule in the last case. |
| 296 | */ |
| 297 | if (paws_reject || th->ack) |
Arnaldo Carvalho de Melo | 696ab2d | 2005-08-09 20:45:03 -0700 | [diff] [blame] | 298 | inet_twsk_schedule(tw, &tcp_death_row, TCP_TIMEWAIT_LEN, |
| 299 | TCP_TIMEWAIT_LEN); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 300 | |
| 301 | /* Send ACK. Note, we do not put the bucket, |
| 302 | * it will be released by caller. |
| 303 | */ |
| 304 | return TCP_TW_ACK; |
| 305 | } |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 306 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 307 | return TCP_TW_SUCCESS; |
| 308 | } |
Eric Dumazet | 4bc2f18 | 2010-07-09 21:22:10 +0000 | [diff] [blame] | 309 | EXPORT_SYMBOL(tcp_timewait_state_process); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 310 | |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 311 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 312 | * Move a socket to time-wait or dead fin-wait-2 state. |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 313 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 314 | void tcp_time_wait(struct sock *sk, int state, int timeo) |
| 315 | { |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 316 | struct inet_timewait_sock *tw = NULL; |
Arnaldo Carvalho de Melo | 8292a17 | 2005-12-13 23:15:52 -0800 | [diff] [blame] | 317 | const struct inet_connection_sock *icsk = inet_csk(sk); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 318 | const struct tcp_sock *tp = tcp_sk(sk); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 319 | int recycle_ok = 0; |
| 320 | |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 321 | 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] | 322 | recycle_ok = tcp_remember_stamp(sk); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 323 | |
Arnaldo Carvalho de Melo | 295ff7e | 2005-08-09 20:44:40 -0700 | [diff] [blame] | 324 | 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] | 325 | tw = inet_twsk_alloc(sk, state); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 326 | |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 327 | if (tw != NULL) { |
| 328 | struct tcp_timewait_sock *tcptw = tcp_twsk((struct sock *)tw); |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 329 | 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] | 330 | |
KOVACS Krisztian | 58af19e | 2011-10-18 10:17:35 +0000 | [diff] [blame] | 331 | tw->tw_transparent = inet_sk(sk)->transparent; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 332 | tw->tw_rcv_wscale = tp->rx_opt.rcv_wscale; |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 333 | tcptw->tw_rcv_nxt = tp->rcv_nxt; |
| 334 | tcptw->tw_snd_nxt = tp->snd_nxt; |
| 335 | tcptw->tw_rcv_wnd = tcp_receive_window(tp); |
| 336 | tcptw->tw_ts_recent = tp->rx_opt.ts_recent; |
| 337 | tcptw->tw_ts_recent_stamp = tp->rx_opt.ts_recent_stamp; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 338 | |
Eric Dumazet | dfd56b8 | 2011-12-10 09:48:31 +0000 | [diff] [blame] | 339 | #if IS_ENABLED(CONFIG_IPV6) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 340 | if (tw->tw_family == PF_INET6) { |
| 341 | struct ipv6_pinfo *np = inet6_sk(sk); |
Arnaldo Carvalho de Melo | 0fa1a53 | 2005-12-13 23:23:09 -0800 | [diff] [blame] | 342 | struct inet6_timewait_sock *tw6; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 343 | |
Arnaldo Carvalho de Melo | 0fa1a53 | 2005-12-13 23:23:09 -0800 | [diff] [blame] | 344 | tw->tw_ipv6_offset = inet6_tw_offset(sk->sk_prot); |
| 345 | tw6 = inet6_twsk((struct sock *)tw); |
Alexey Dobriyan | 4e3fd7a | 2011-11-21 03:39:03 +0000 | [diff] [blame] | 346 | tw6->tw_v6_daddr = np->daddr; |
| 347 | tw6->tw_v6_rcv_saddr = np->rcv_saddr; |
Eric Dumazet | b903d32 | 2011-10-27 00:44:35 -0400 | [diff] [blame] | 348 | tw->tw_tclass = np->tclass; |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 349 | tw->tw_ipv6only = np->ipv6only; |
Arnaldo Carvalho de Melo | c676270 | 2005-08-09 20:09:59 -0700 | [diff] [blame] | 350 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 351 | #endif |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 352 | |
| 353 | #ifdef CONFIG_TCP_MD5SIG |
| 354 | /* |
| 355 | * The timewait bucket does not have the key DB from the |
| 356 | * sock structure. We just make a quick copy of the |
| 357 | * md5 key being used (if indeed we are using one) |
| 358 | * so the timewait ack generating code has the key. |
| 359 | */ |
| 360 | do { |
| 361 | struct tcp_md5sig_key *key; |
| 362 | memset(tcptw->tw_md5_key, 0, sizeof(tcptw->tw_md5_key)); |
| 363 | tcptw->tw_md5_keylen = 0; |
| 364 | key = tp->af_specific->md5_lookup(sk, sk); |
| 365 | if (key != NULL) { |
| 366 | memcpy(&tcptw->tw_md5_key, key->key, key->keylen); |
| 367 | tcptw->tw_md5_keylen = key->keylen; |
Wu Fengguang | aa13307 | 2009-09-02 23:45:45 -0700 | [diff] [blame] | 368 | if (tcp_alloc_md5sig_pool(sk) == NULL) |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 369 | BUG(); |
| 370 | } |
Stephen Hemminger | 2de979b | 2007-03-08 20:45:19 -0800 | [diff] [blame] | 371 | } while (0); |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 372 | #endif |
| 373 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 374 | /* Linkage updates. */ |
Arnaldo Carvalho de Melo | e48c414 | 2005-08-09 20:09:46 -0700 | [diff] [blame] | 375 | __inet_twsk_hashdance(tw, sk, &tcp_hashinfo); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 376 | |
| 377 | /* Get the TIME_WAIT timeout firing. */ |
| 378 | if (timeo < rto) |
| 379 | timeo = rto; |
| 380 | |
| 381 | if (recycle_ok) { |
| 382 | tw->tw_timeout = rto; |
| 383 | } else { |
| 384 | tw->tw_timeout = TCP_TIMEWAIT_LEN; |
| 385 | if (state == TCP_TIME_WAIT) |
| 386 | timeo = TCP_TIMEWAIT_LEN; |
| 387 | } |
| 388 | |
Arnaldo Carvalho de Melo | 696ab2d | 2005-08-09 20:45:03 -0700 | [diff] [blame] | 389 | inet_twsk_schedule(tw, &tcp_death_row, timeo, |
| 390 | TCP_TIMEWAIT_LEN); |
Arnaldo Carvalho de Melo | 8feaf0c0 | 2005-08-09 20:09:30 -0700 | [diff] [blame] | 391 | inet_twsk_put(tw); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 392 | } else { |
| 393 | /* Sorry, if we're out of memory, just CLOSE this |
| 394 | * socket up. We've got bigger problems than |
| 395 | * non-graceful socket closings. |
| 396 | */ |
Tom Herbert | 6763151 | 2010-12-08 12:16:33 -0800 | [diff] [blame] | 397 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPTIMEWAITOVERFLOW); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 398 | } |
| 399 | |
| 400 | tcp_update_metrics(sk); |
| 401 | tcp_done(sk); |
| 402 | } |
| 403 | |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 404 | void tcp_twsk_destructor(struct sock *sk) |
| 405 | { |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 406 | #ifdef CONFIG_TCP_MD5SIG |
David S. Miller | a928630 | 2006-11-14 19:53:22 -0800 | [diff] [blame] | 407 | struct tcp_timewait_sock *twsk = tcp_twsk(sk); |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 408 | if (twsk->tw_md5_keylen) |
Robert Varga | 657e964 | 2009-09-15 23:49:21 -0700 | [diff] [blame] | 409 | tcp_free_md5sig_pool(); |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 410 | #endif |
| 411 | } |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 412 | EXPORT_SYMBOL_GPL(tcp_twsk_destructor); |
| 413 | |
Ilpo Järvinen | bdf1ee5 | 2007-05-27 02:04:16 -0700 | [diff] [blame] | 414 | static inline void TCP_ECN_openreq_child(struct tcp_sock *tp, |
| 415 | struct request_sock *req) |
| 416 | { |
| 417 | tp->ecn_flags = inet_rsk(req)->ecn_ok ? TCP_ECN_OK : 0; |
| 418 | } |
| 419 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 420 | /* This is not only more efficient than what we used to do, it eliminates |
| 421 | * a lot of code duplication between IPv4/IPv6 SYN recv processing. -DaveM |
| 422 | * |
| 423 | * Actually, we could lots of memory writes here. tp of listening |
| 424 | * socket contains all necessary default parameters. |
| 425 | */ |
Arnaldo Carvalho de Melo | 60236fd | 2005-06-18 22:47:21 -0700 | [diff] [blame] | 426 | 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] | 427 | { |
Eric Dumazet | e56c57d | 2011-11-08 17:07:07 -0500 | [diff] [blame] | 428 | struct sock *newsk = inet_csk_clone_lock(sk, req, GFP_ATOMIC); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 429 | |
Arnaldo Carvalho de Melo | 87d11ce | 2005-08-09 20:10:12 -0700 | [diff] [blame] | 430 | if (newsk != NULL) { |
Arnaldo Carvalho de Melo | 9f1d260 | 2005-08-09 20:11:24 -0700 | [diff] [blame] | 431 | const struct inet_request_sock *ireq = inet_rsk(req); |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 432 | struct tcp_request_sock *treq = tcp_rsk(req); |
Arnaldo Carvalho de Melo | a9948a7 | 2007-02-28 11:05:56 -0800 | [diff] [blame] | 433 | struct inet_connection_sock *newicsk = inet_csk(newsk); |
William Allen Simpson | 435cf55 | 2009-12-02 18:17:05 +0000 | [diff] [blame] | 434 | struct tcp_sock *newtp = tcp_sk(newsk); |
| 435 | struct tcp_sock *oldtp = tcp_sk(sk); |
| 436 | struct tcp_cookie_values *oldcvp = oldtp->cookie_values; |
| 437 | |
| 438 | /* TCP Cookie Transactions require space for the cookie pair, |
| 439 | * as it differs for each connection. There is no need to |
| 440 | * copy any s_data_payload stored at the original socket. |
| 441 | * Failure will prevent resuming the connection. |
| 442 | * |
| 443 | * Presumed copied, in order of appearance: |
| 444 | * cookie_in_always, cookie_out_never |
| 445 | */ |
| 446 | if (oldcvp != NULL) { |
| 447 | struct tcp_cookie_values *newcvp = |
| 448 | kzalloc(sizeof(*newtp->cookie_values), |
| 449 | GFP_ATOMIC); |
| 450 | |
| 451 | if (newcvp != NULL) { |
| 452 | kref_init(&newcvp->kref); |
| 453 | newcvp->cookie_desired = |
| 454 | oldcvp->cookie_desired; |
| 455 | newtp->cookie_values = newcvp; |
| 456 | } else { |
| 457 | /* Not Yet Implemented */ |
| 458 | newtp->cookie_values = NULL; |
| 459 | } |
| 460 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 461 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 462 | /* Now setup tcp_sock */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 463 | newtp->pred_flags = 0; |
William Allen Simpson | 435cf55 | 2009-12-02 18:17:05 +0000 | [diff] [blame] | 464 | |
| 465 | newtp->rcv_wup = newtp->copied_seq = |
| 466 | newtp->rcv_nxt = treq->rcv_isn + 1; |
| 467 | |
| 468 | newtp->snd_sml = newtp->snd_una = |
| 469 | newtp->snd_nxt = newtp->snd_up = |
| 470 | treq->snt_isn + 1 + tcp_s_data_size(oldtp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 471 | |
| 472 | tcp_prequeue_init(newtp); |
| 473 | |
Hantzis Fotis | ee7537b | 2009-03-02 22:42:02 -0800 | [diff] [blame] | 474 | tcp_init_wl(newtp, treq->rcv_isn); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 475 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 476 | newtp->srtt = 0; |
| 477 | newtp->mdev = TCP_TIMEOUT_INIT; |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 478 | newicsk->icsk_rto = TCP_TIMEOUT_INIT; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 479 | |
| 480 | newtp->packets_out = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 481 | newtp->retrans_out = 0; |
| 482 | newtp->sacked_out = 0; |
| 483 | newtp->fackets_out = 0; |
Ilpo Järvinen | 0b6a05c | 2009-09-15 01:30:10 -0700 | [diff] [blame] | 484 | newtp->snd_ssthresh = TCP_INFINITE_SSTHRESH; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 485 | |
| 486 | /* So many TCP implementations out there (incorrectly) count the |
| 487 | * initial SYN frame in their delayed-ACK and congestion control |
| 488 | * algorithms that we must have the following bandaid to talk |
| 489 | * efficiently to them. -DaveM |
| 490 | */ |
Jerry Chu | 9ad7c04 | 2011-06-08 11:08:38 +0000 | [diff] [blame] | 491 | newtp->snd_cwnd = TCP_INIT_CWND; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 492 | newtp->snd_cwnd_cnt = 0; |
Stephen Hemminger | 9772efb | 2005-11-10 17:09:53 -0800 | [diff] [blame] | 493 | newtp->bytes_acked = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 494 | |
| 495 | newtp->frto_counter = 0; |
| 496 | newtp->frto_highmark = 0; |
| 497 | |
Eric Dumazet | d8a6e65 | 2011-11-30 01:02:41 +0000 | [diff] [blame] | 498 | if (newicsk->icsk_ca_ops != &tcp_init_congestion_ops && |
| 499 | !try_module_get(newicsk->icsk_ca_ops->owner)) |
| 500 | newicsk->icsk_ca_ops = &tcp_init_congestion_ops; |
Stephen Hemminger | 317a76f | 2005-06-23 12:19:55 -0700 | [diff] [blame] | 501 | |
Arnaldo Carvalho de Melo | 6687e98 | 2005-08-10 04:03:31 -0300 | [diff] [blame] | 502 | tcp_set_ca_state(newsk, TCP_CA_Open); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 503 | tcp_init_xmit_timers(newsk); |
| 504 | skb_queue_head_init(&newtp->out_of_order_queue); |
William Allen Simpson | 435cf55 | 2009-12-02 18:17:05 +0000 | [diff] [blame] | 505 | newtp->write_seq = newtp->pushed_seq = |
| 506 | treq->snt_isn + 1 + tcp_s_data_size(oldtp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 507 | |
| 508 | newtp->rx_opt.saw_tstamp = 0; |
| 509 | |
| 510 | newtp->rx_opt.dsack = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 511 | newtp->rx_opt.num_sacks = 0; |
Ilpo Järvinen | cabeccb | 2009-02-28 04:44:38 +0000 | [diff] [blame] | 512 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 513 | newtp->urg_data = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 514 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 515 | if (sock_flag(newsk, SOCK_KEEPOPEN)) |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 516 | inet_csk_reset_keepalive_timer(newsk, |
| 517 | keepalive_time_when(newtp)); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 518 | |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 519 | newtp->rx_opt.tstamp_ok = ireq->tstamp_ok; |
Stephen Hemminger | 2de979b | 2007-03-08 20:45:19 -0800 | [diff] [blame] | 520 | if ((newtp->rx_opt.sack_ok = ireq->sack_ok) != 0) { |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 521 | if (sysctl_tcp_fack) |
Ilpo Järvinen | e60402d | 2007-08-09 15:14:46 +0300 | [diff] [blame] | 522 | tcp_enable_fack(newtp); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 523 | } |
| 524 | newtp->window_clamp = req->window_clamp; |
| 525 | newtp->rcv_ssthresh = req->rcv_wnd; |
| 526 | newtp->rcv_wnd = req->rcv_wnd; |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 527 | newtp->rx_opt.wscale_ok = ireq->wscale_ok; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 528 | if (newtp->rx_opt.wscale_ok) { |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 529 | newtp->rx_opt.snd_wscale = ireq->snd_wscale; |
| 530 | newtp->rx_opt.rcv_wscale = ireq->rcv_wscale; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 531 | } else { |
| 532 | newtp->rx_opt.snd_wscale = newtp->rx_opt.rcv_wscale = 0; |
| 533 | newtp->window_clamp = min(newtp->window_clamp, 65535U); |
| 534 | } |
Arnaldo Carvalho de Melo | aa8223c | 2007-04-10 21:04:22 -0700 | [diff] [blame] | 535 | newtp->snd_wnd = (ntohs(tcp_hdr(skb)->window) << |
| 536 | newtp->rx_opt.snd_wscale); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 537 | newtp->max_window = newtp->snd_wnd; |
| 538 | |
| 539 | if (newtp->rx_opt.tstamp_ok) { |
| 540 | newtp->rx_opt.ts_recent = req->ts_recent; |
James Morris | 9d729f7 | 2007-03-04 16:12:44 -0800 | [diff] [blame] | 541 | newtp->rx_opt.ts_recent_stamp = get_seconds(); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 542 | newtp->tcp_header_len = sizeof(struct tcphdr) + TCPOLEN_TSTAMP_ALIGNED; |
| 543 | } else { |
| 544 | newtp->rx_opt.ts_recent_stamp = 0; |
| 545 | newtp->tcp_header_len = sizeof(struct tcphdr); |
| 546 | } |
YOSHIFUJI Hideaki | cfb6eeb | 2006-11-14 19:07:45 -0800 | [diff] [blame] | 547 | #ifdef CONFIG_TCP_MD5SIG |
| 548 | newtp->md5sig_info = NULL; /*XXX*/ |
| 549 | if (newtp->af_specific->md5_lookup(sk, newsk)) |
| 550 | newtp->tcp_header_len += TCPOLEN_MD5SIG_ALIGNED; |
| 551 | #endif |
William Allen Simpson | bee7ca9 | 2009-11-10 09:51:18 +0000 | [diff] [blame] | 552 | if (skb->len >= TCP_MSS_DEFAULT + newtp->tcp_header_len) |
Arnaldo Carvalho de Melo | 463c84b | 2005-08-09 20:10:42 -0700 | [diff] [blame] | 553 | newicsk->icsk_ack.last_seg_size = skb->len - newtp->tcp_header_len; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 554 | newtp->rx_opt.mss_clamp = req->mss; |
| 555 | TCP_ECN_openreq_child(newtp, req); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 556 | |
Pavel Emelyanov | 63231bd | 2008-07-16 20:22:25 -0700 | [diff] [blame] | 557 | TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_PASSIVEOPENS); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 558 | } |
| 559 | return newsk; |
| 560 | } |
Eric Dumazet | 4bc2f18 | 2010-07-09 21:22:10 +0000 | [diff] [blame] | 561 | EXPORT_SYMBOL(tcp_create_openreq_child); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 562 | |
YOSHIFUJI Hideaki | e905a9e | 2007-02-09 23:24:47 +0900 | [diff] [blame] | 563 | /* |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 564 | * Process an incoming packet for SYN_RECV sockets represented |
Arnaldo Carvalho de Melo | 60236fd | 2005-06-18 22:47:21 -0700 | [diff] [blame] | 565 | * as a request_sock. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 566 | */ |
| 567 | |
Jianjun Kong | 5a5f3a8 | 2008-11-03 00:24:34 -0800 | [diff] [blame] | 568 | 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] | 569 | struct request_sock *req, |
| 570 | struct request_sock **prev) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 571 | { |
William Allen Simpson | 4957faade | 2009-12-02 18:25:27 +0000 | [diff] [blame] | 572 | struct tcp_options_received tmp_opt; |
Eric Dumazet | cf533ea | 2011-10-21 05:22:42 -0400 | [diff] [blame] | 573 | const u8 *hash_location; |
William Allen Simpson | 4957faade | 2009-12-02 18:25:27 +0000 | [diff] [blame] | 574 | struct sock *child; |
Arnaldo Carvalho de Melo | aa8223c | 2007-04-10 21:04:22 -0700 | [diff] [blame] | 575 | const struct tcphdr *th = tcp_hdr(skb); |
Al Viro | 714e85b | 2006-11-14 20:51:49 -0800 | [diff] [blame] | 576 | __be32 flg = tcp_flag_word(th) & (TCP_FLAG_RST|TCP_FLAG_SYN|TCP_FLAG_ACK); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 577 | int paws_reject = 0; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 578 | |
David S. Miller | bb5b7c1 | 2009-12-15 20:56:42 -0800 | [diff] [blame] | 579 | tmp_opt.saw_tstamp = 0; |
| 580 | if (th->doff > (sizeof(struct tcphdr)>>2)) { |
| 581 | tcp_parse_options(skb, &tmp_opt, &hash_location, 0); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 582 | |
| 583 | if (tmp_opt.saw_tstamp) { |
| 584 | tmp_opt.ts_recent = req->ts_recent; |
| 585 | /* We do not store true stamp, but it is not required, |
| 586 | * it can be estimated (approximately) |
| 587 | * from another data. |
| 588 | */ |
James Morris | 9d729f7 | 2007-03-04 16:12:44 -0800 | [diff] [blame] | 589 | tmp_opt.ts_recent_stamp = get_seconds() - ((TCP_TIMEOUT_INIT/HZ)<<req->retrans); |
Ilpo Järvinen | c887e6d | 2009-03-14 14:23:03 +0000 | [diff] [blame] | 590 | paws_reject = tcp_paws_reject(&tmp_opt, th->rst); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 591 | } |
| 592 | } |
| 593 | |
| 594 | /* Check for pure retransmitted SYN. */ |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 595 | if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn && |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 596 | flg == TCP_FLAG_SYN && |
| 597 | !paws_reject) { |
| 598 | /* |
| 599 | * RFC793 draws (Incorrectly! It was fixed in RFC1122) |
| 600 | * this case on figure 6 and figure 8, but formal |
| 601 | * protocol description says NOTHING. |
| 602 | * To be more exact, it says that we should send ACK, |
| 603 | * because this segment (at least, if it has no data) |
| 604 | * is out of window. |
| 605 | * |
| 606 | * CONCLUSION: RFC793 (even with RFC1122) DOES NOT |
| 607 | * describe SYN-RECV state. All the description |
| 608 | * is wrong, we cannot believe to it and should |
| 609 | * rely only on common sense and implementation |
| 610 | * experience. |
| 611 | * |
| 612 | * Enforce "SYN-ACK" according to figure 8, figure 6 |
| 613 | * of RFC793, fixed by RFC1122. |
| 614 | */ |
William Allen Simpson | e6b4d11 | 2009-12-02 18:07:39 +0000 | [diff] [blame] | 615 | req->rsk_ops->rtx_syn_ack(sk, req, NULL); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 616 | return NULL; |
| 617 | } |
| 618 | |
| 619 | /* Further reproduces section "SEGMENT ARRIVES" |
| 620 | for state SYN-RECEIVED of RFC793. |
| 621 | It is broken, however, it does not work only |
| 622 | when SYNs are crossed. |
| 623 | |
| 624 | You would think that SYN crossing is impossible here, since |
| 625 | we should have a SYN_SENT socket (from connect()) on our end, |
| 626 | but this is not true if the crossed SYNs were sent to both |
| 627 | ends by a malicious third party. We must defend against this, |
| 628 | and to do that we first verify the ACK (as per RFC793, page |
| 629 | 36) and reset if it is invalid. Is this a true full defense? |
| 630 | To convince ourselves, let us consider a way in which the ACK |
| 631 | test can still pass in this 'malicious crossed SYNs' case. |
| 632 | Malicious sender sends identical SYNs (and thus identical sequence |
| 633 | numbers) to both A and B: |
| 634 | |
| 635 | A: gets SYN, seq=7 |
| 636 | B: gets SYN, seq=7 |
| 637 | |
| 638 | By our good fortune, both A and B select the same initial |
| 639 | send sequence number of seven :-) |
| 640 | |
| 641 | A: sends SYN|ACK, seq=7, ack_seq=8 |
| 642 | B: sends SYN|ACK, seq=7, ack_seq=8 |
| 643 | |
| 644 | So we are now A eating this SYN|ACK, ACK test passes. So |
| 645 | does sequence test, SYN is truncated, and thus we consider |
| 646 | it a bare ACK. |
| 647 | |
David S. Miller | ec0a196 | 2008-06-12 16:31:35 -0700 | [diff] [blame] | 648 | If icsk->icsk_accept_queue.rskq_defer_accept, we silently drop this |
| 649 | bare ACK. Otherwise, we create an established connection. Both |
| 650 | ends (listening sockets) accept the new incoming connection and try |
| 651 | to talk to each other. 8-) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 652 | |
| 653 | Note: This case is both harmless, and rare. Possibility is about the |
| 654 | same as us discovering intelligent life on another plant tomorrow. |
| 655 | |
| 656 | But generally, we should (RFC lies!) to accept ACK |
| 657 | from SYNACK both here and in tcp_rcv_state_process(). |
| 658 | tcp_rcv_state_process() does not, hence, we do not too. |
| 659 | |
| 660 | Note that the case is absolutely generic: |
| 661 | we cannot optimize anything here without |
| 662 | violating protocol. All the checks must be made |
| 663 | before attempt to create socket. |
| 664 | */ |
| 665 | |
| 666 | /* RFC793 page 36: "If the connection is in any non-synchronized state ... |
| 667 | * and the incoming segment acknowledges something not yet |
Stephen Hemminger | caa20d9a | 2005-11-10 17:13:47 -0800 | [diff] [blame] | 668 | * sent (the segment carries an unacceptable ACK) ... |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 669 | * a reset is sent." |
| 670 | * |
| 671 | * Invalid ACK: reset will be sent by listening socket |
| 672 | */ |
| 673 | if ((flg & TCP_FLAG_ACK) && |
William Allen Simpson | 435cf55 | 2009-12-02 18:17:05 +0000 | [diff] [blame] | 674 | (TCP_SKB_CB(skb)->ack_seq != |
| 675 | tcp_rsk(req)->snt_isn + 1 + tcp_s_data_size(tcp_sk(sk)))) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 676 | return sk; |
| 677 | |
| 678 | /* Also, it would be not so bad idea to check rcv_tsecr, which |
| 679 | * is essentially ACK extension and too early or too late values |
| 680 | * should cause reset in unsynchronized states. |
| 681 | */ |
| 682 | |
| 683 | /* RFC793: "first check sequence number". */ |
| 684 | |
| 685 | 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] | 686 | 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] | 687 | /* Out of window: send ACK and drop. */ |
| 688 | if (!(flg & TCP_FLAG_RST)) |
Gui Jianfeng | 6edafaa | 2008-08-06 23:50:04 -0700 | [diff] [blame] | 689 | req->rsk_ops->send_ack(sk, skb, req); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 690 | if (paws_reject) |
Pavel Emelyanov | de0744a | 2008-07-16 20:31:16 -0700 | [diff] [blame] | 691 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_PAWSESTABREJECTED); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 692 | return NULL; |
| 693 | } |
| 694 | |
| 695 | /* In sequence, PAWS is OK. */ |
| 696 | |
Arnaldo Carvalho de Melo | 2e6599c | 2005-06-18 22:46:52 -0700 | [diff] [blame] | 697 | if (tmp_opt.saw_tstamp && !after(TCP_SKB_CB(skb)->seq, tcp_rsk(req)->rcv_isn + 1)) |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 698 | req->ts_recent = tmp_opt.rcv_tsval; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 699 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 700 | if (TCP_SKB_CB(skb)->seq == tcp_rsk(req)->rcv_isn) { |
| 701 | /* Truncate SYN, it is out of window starting |
| 702 | at tcp_rsk(req)->rcv_isn + 1. */ |
| 703 | flg &= ~TCP_FLAG_SYN; |
| 704 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 705 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 706 | /* RFC793: "second check the RST bit" and |
| 707 | * "fourth, check the SYN bit" |
| 708 | */ |
| 709 | if (flg & (TCP_FLAG_RST|TCP_FLAG_SYN)) { |
| 710 | TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_ATTEMPTFAILS); |
| 711 | goto embryonic_reset; |
| 712 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 713 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 714 | /* ACK sequence verified above, just make sure ACK is |
| 715 | * set. If ACK not set, just silently drop the packet. |
| 716 | */ |
| 717 | if (!(flg & TCP_FLAG_ACK)) |
| 718 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 719 | |
Julian Anastasov | d1b99ba | 2009-10-19 10:01:56 +0000 | [diff] [blame] | 720 | /* While TCP_DEFER_ACCEPT is active, drop bare ACK. */ |
| 721 | if (req->retrans < inet_csk(sk)->icsk_accept_queue.rskq_defer_accept && |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 722 | TCP_SKB_CB(skb)->end_seq == tcp_rsk(req)->rcv_isn + 1) { |
| 723 | inet_rsk(req)->acked = 1; |
Eric Dumazet | 907cdda | 2010-03-19 05:37:18 +0000 | [diff] [blame] | 724 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPDEFERACCEPTDROP); |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 725 | return NULL; |
| 726 | } |
Jerry Chu | 9ad7c04 | 2011-06-08 11:08:38 +0000 | [diff] [blame] | 727 | if (tmp_opt.saw_tstamp && tmp_opt.rcv_tsecr) |
| 728 | tcp_rsk(req)->snt_synack = tmp_opt.rcv_tsecr; |
| 729 | else if (req->retrans) /* don't take RTT sample if retrans && ~TS */ |
| 730 | tcp_rsk(req)->snt_synack = 0; |
David S. Miller | ec0a196 | 2008-06-12 16:31:35 -0700 | [diff] [blame] | 731 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 732 | /* OK, ACK is valid, create big socket and |
| 733 | * feed this segment to it. It will repeat all |
| 734 | * the tests. THIS SEGMENT MUST MOVE SOCKET TO |
| 735 | * ESTABLISHED STATE. If it will be dropped after |
| 736 | * socket is created, wait for troubles. |
| 737 | */ |
| 738 | child = inet_csk(sk)->icsk_af_ops->syn_recv_sock(sk, skb, req, NULL); |
| 739 | if (child == NULL) |
| 740 | goto listen_overflow; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 741 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 742 | inet_csk_reqsk_queue_unlink(sk, req, prev); |
| 743 | inet_csk_reqsk_queue_removed(sk, req); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 744 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 745 | inet_csk_reqsk_queue_add(sk, req, child); |
| 746 | return child; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 747 | |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 748 | listen_overflow: |
| 749 | if (!sysctl_tcp_abort_on_overflow) { |
| 750 | inet_rsk(req)->acked = 1; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 751 | return NULL; |
Adam Langley | 2aaab9a | 2008-08-07 20:27:45 -0700 | [diff] [blame] | 752 | } |
| 753 | |
| 754 | embryonic_reset: |
| 755 | NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_EMBRYONICRSTS); |
| 756 | if (!(flg & TCP_FLAG_RST)) |
| 757 | req->rsk_ops->send_reset(sk, skb); |
| 758 | |
| 759 | inet_csk_reqsk_queue_drop(sk, req, prev); |
| 760 | return NULL; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 761 | } |
Eric Dumazet | 4bc2f18 | 2010-07-09 21:22:10 +0000 | [diff] [blame] | 762 | EXPORT_SYMBOL(tcp_check_req); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 763 | |
| 764 | /* |
| 765 | * Queue segment on the new socket if the new socket is active, |
| 766 | * otherwise we just shortcircuit this and continue with |
| 767 | * the new socket. |
| 768 | */ |
| 769 | |
| 770 | int tcp_child_process(struct sock *parent, struct sock *child, |
| 771 | struct sk_buff *skb) |
| 772 | { |
| 773 | int ret = 0; |
| 774 | int state = child->sk_state; |
| 775 | |
| 776 | if (!sock_owned_by_user(child)) { |
Arnaldo Carvalho de Melo | aa8223c | 2007-04-10 21:04:22 -0700 | [diff] [blame] | 777 | ret = tcp_rcv_state_process(child, skb, tcp_hdr(skb), |
| 778 | skb->len); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 779 | /* Wakeup parent, send SIGIO */ |
| 780 | if (state == TCP_SYN_RECV && child->sk_state != state) |
| 781 | parent->sk_data_ready(parent, 0); |
| 782 | } else { |
| 783 | /* Alas, it is possible again, because we do lookup |
| 784 | * in main socket hash table and lock on listening |
| 785 | * socket does not protect us more. |
| 786 | */ |
Zhu Yi | a3a858f | 2010-03-04 18:01:47 +0000 | [diff] [blame] | 787 | __sk_add_backlog(child, skb); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 788 | } |
| 789 | |
| 790 | bh_unlock_sock(child); |
| 791 | sock_put(child); |
| 792 | return ret; |
| 793 | } |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 794 | EXPORT_SYMBOL(tcp_child_process); |