Commit | Line | Data |
---|---|---|
2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
1da177e4 LT |
2 | /* |
3 | * Syncookies implementation for the Linux kernel | |
4 | * | |
5 | * Copyright (C) 1997 Andi Kleen | |
e905a9ed | 6 | * Based on ideas by D.J.Bernstein and Eric Schenk. |
1da177e4 LT |
7 | */ |
8 | ||
9 | #include <linux/tcp.h> | |
10 | #include <linux/slab.h> | |
11 | #include <linux/random.h> | |
fe62d05b | 12 | #include <linux/siphash.h> |
1da177e4 | 13 | #include <linux/kernel.h> |
bc3b2d7f | 14 | #include <linux/export.h> |
84b114b9 | 15 | #include <net/secure_seq.h> |
1da177e4 | 16 | #include <net/tcp.h> |
86b08d86 | 17 | #include <net/route.h> |
1da177e4 | 18 | |
fe62d05b | 19 | static siphash_key_t syncookie_secret[2] __read_mostly; |
1da177e4 LT |
20 | |
21 | #define COOKIEBITS 24 /* Upper bits store count */ | |
22 | #define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1) | |
23 | ||
274e2da0 FW |
24 | /* TCP Timestamp: 6 lowest bits of timestamp sent in the cookie SYN-ACK |
25 | * stores TCP options: | |
26 | * | |
27 | * MSB LSB | |
28 | * | 31 ... 6 | 5 | 4 | 3 2 1 0 | | |
29 | * | Timestamp | ECN | SACK | WScale | | |
30 | * | |
31 | * When we receive a valid cookie-ACK, we look at the echoed tsval (if | |
32 | * any) to figure out which TCP options we should use for the rebuilt | |
33 | * connection. | |
34 | * | |
35 | * A WScale setting of '0xf' (which is an invalid scaling value) | |
36 | * means that original syn did not include the TCP window scaling option. | |
37 | */ | |
38 | #define TS_OPT_WSCALE_MASK 0xf | |
39 | #define TS_OPT_SACK BIT(4) | |
40 | #define TS_OPT_ECN BIT(5) | |
41 | /* There is no TS_OPT_TIMESTAMP: | |
42 | * if ACK contains timestamp option, we already know it was | |
43 | * requested/supported by the syn/synack exchange. | |
44 | */ | |
45 | #define TSBITS 6 | |
46 | #define TSMASK (((__u32)1 << TSBITS) - 1) | |
47 | ||
714e85be | 48 | static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport, |
1da177e4 LT |
49 | u32 count, int c) |
50 | { | |
b23a002f | 51 | net_get_random_once(syncookie_secret, sizeof(syncookie_secret)); |
fe62d05b JD |
52 | return siphash_4u32((__force u32)saddr, (__force u32)daddr, |
53 | (__force u32)sport << 16 | (__force u32)dport, | |
54 | count, &syncookie_secret[c]); | |
1da177e4 LT |
55 | } |
56 | ||
4dfc2817 FW |
57 | |
58 | /* | |
59 | * when syncookies are in effect and tcp timestamps are enabled we encode | |
734f614b | 60 | * tcp options in the lower bits of the timestamp value that will be |
4dfc2817 FW |
61 | * sent in the syn-ack. |
62 | * Since subsequent timestamps use the normal tcp_time_stamp value, we | |
63 | * must make sure that the resulting initial timestamp is <= tcp_time_stamp. | |
64 | */ | |
200ecef6 | 65 | u64 cookie_init_timestamp(struct request_sock *req, u64 now) |
4dfc2817 FW |
66 | { |
67 | struct inet_request_sock *ireq; | |
200ecef6 | 68 | u32 ts, ts_now = tcp_ns_to_ts(now); |
4dfc2817 FW |
69 | u32 options = 0; |
70 | ||
71 | ireq = inet_rsk(req); | |
734f614b | 72 | |
274e2da0 FW |
73 | options = ireq->wscale_ok ? ireq->snd_wscale : TS_OPT_WSCALE_MASK; |
74 | if (ireq->sack_ok) | |
75 | options |= TS_OPT_SACK; | |
76 | if (ireq->ecn_ok) | |
77 | options |= TS_OPT_ECN; | |
4dfc2817 FW |
78 | |
79 | ts = ts_now & ~TSMASK; | |
80 | ts |= options; | |
81 | if (ts > ts_now) { | |
82 | ts >>= TSBITS; | |
83 | ts--; | |
84 | ts <<= TSBITS; | |
85 | ts |= options; | |
86 | } | |
d3edd06e | 87 | return (u64)ts * (NSEC_PER_SEC / TCP_TS_HZ); |
4dfc2817 FW |
88 | } |
89 | ||
90 | ||
714e85be | 91 | static __u32 secure_tcp_syn_cookie(__be32 saddr, __be32 daddr, __be16 sport, |
8c27bd75 | 92 | __be16 dport, __u32 sseq, __u32 data) |
1da177e4 LT |
93 | { |
94 | /* | |
95 | * Compute the secure sequence number. | |
96 | * The output should be: | |
e905a9ed | 97 | * HASH(sec1,saddr,sport,daddr,dport,sec1) + sseq + (count * 2^24) |
1da177e4 LT |
98 | * + (HASH(sec2,saddr,sport,daddr,dport,count,sec2) % 2^24). |
99 | * Where sseq is their sequence number and count increases every | |
100 | * minute by 1. | |
101 | * As an extra hack, we add a small "data" value that encodes the | |
102 | * MSS into the second hash value. | |
103 | */ | |
8c27bd75 | 104 | u32 count = tcp_cookie_time(); |
1da177e4 LT |
105 | return (cookie_hash(saddr, daddr, sport, dport, 0, 0) + |
106 | sseq + (count << COOKIEBITS) + | |
107 | ((cookie_hash(saddr, daddr, sport, dport, count, 1) + data) | |
108 | & COOKIEMASK)); | |
109 | } | |
110 | ||
111 | /* | |
112 | * This retrieves the small "data" value from the syncookie. | |
113 | * If the syncookie is bad, the data returned will be out of | |
114 | * range. This must be checked by the caller. | |
115 | * | |
8c27bd75 FW |
116 | * The count value used to generate the cookie must be less than |
117 | * MAX_SYNCOOKIE_AGE minutes in the past. | |
118 | * The return value (__u32)-1 if this test fails. | |
1da177e4 | 119 | */ |
714e85be | 120 | static __u32 check_tcp_syn_cookie(__u32 cookie, __be32 saddr, __be32 daddr, |
8c27bd75 | 121 | __be16 sport, __be16 dport, __u32 sseq) |
1da177e4 | 122 | { |
8c27bd75 | 123 | u32 diff, count = tcp_cookie_time(); |
1da177e4 LT |
124 | |
125 | /* Strip away the layers from the cookie */ | |
126 | cookie -= cookie_hash(saddr, daddr, sport, dport, 0, 0) + sseq; | |
127 | ||
128 | /* Cookie is now reduced to (count * 2^24) ^ (hash % 2^24) */ | |
0c9a67d2 | 129 | diff = (count - (cookie >> COOKIEBITS)) & ((__u32) -1 >> COOKIEBITS); |
8c27bd75 | 130 | if (diff >= MAX_SYNCOOKIE_AGE) |
1da177e4 LT |
131 | return (__u32)-1; |
132 | ||
133 | return (cookie - | |
134 | cookie_hash(saddr, daddr, sport, dport, count - diff, 1)) | |
135 | & COOKIEMASK; /* Leaving the data behind */ | |
136 | } | |
137 | ||
e905a9ed | 138 | /* |
08629354 FW |
139 | * MSS Values are chosen based on the 2011 paper |
140 | * 'An Analysis of TCP Maximum Segement Sizes' by S. Alcock and R. Nelson. | |
141 | * Values .. | |
142 | * .. lower than 536 are rare (< 0.2%) | |
143 | * .. between 537 and 1299 account for less than < 1.5% of observed values | |
144 | * .. in the 1300-1349 range account for about 15 to 20% of observed mss values | |
145 | * .. exceeding 1460 are very rare (< 0.04%) | |
5918e2fb | 146 | * |
08629354 FW |
147 | * 1460 is the single most frequently announced mss value (30 to 46% depending |
148 | * on monitor location). Table must be sorted. | |
1da177e4 LT |
149 | */ |
150 | static __u16 const msstab[] = { | |
5918e2fb | 151 | 536, |
08629354 FW |
152 | 1300, |
153 | 1440, /* 1440, 1452: PPPoE */ | |
5918e2fb | 154 | 1460, |
1da177e4 | 155 | }; |
1da177e4 LT |
156 | |
157 | /* | |
158 | * Generate a syncookie. mssp points to the mss, which is returned | |
159 | * rounded down to the value encoded in the cookie. | |
160 | */ | |
0198230b PM |
161 | u32 __cookie_v4_init_sequence(const struct iphdr *iph, const struct tcphdr *th, |
162 | u16 *mssp) | |
1da177e4 | 163 | { |
1da177e4 LT |
164 | int mssind; |
165 | const __u16 mss = *mssp; | |
166 | ||
5918e2fb FW |
167 | for (mssind = ARRAY_SIZE(msstab) - 1; mssind ; mssind--) |
168 | if (mss >= msstab[mssind]) | |
169 | break; | |
170 | *mssp = msstab[mssind]; | |
1da177e4 | 171 | |
aa8223c7 ACM |
172 | return secure_tcp_syn_cookie(iph->saddr, iph->daddr, |
173 | th->source, th->dest, ntohl(th->seq), | |
8c27bd75 | 174 | mssind); |
1da177e4 | 175 | } |
0198230b PM |
176 | EXPORT_SYMBOL_GPL(__cookie_v4_init_sequence); |
177 | ||
3f684b4b | 178 | __u32 cookie_v4_init_sequence(const struct sk_buff *skb, __u16 *mssp) |
0198230b PM |
179 | { |
180 | const struct iphdr *iph = ip_hdr(skb); | |
181 | const struct tcphdr *th = tcp_hdr(skb); | |
182 | ||
0198230b PM |
183 | return __cookie_v4_init_sequence(iph, th, mssp); |
184 | } | |
1da177e4 | 185 | |
e905a9ed YH |
186 | /* |
187 | * Check if a ack sequence number is a valid syncookie. | |
1da177e4 LT |
188 | * Return the decoded mss if it is, or 0 if not. |
189 | */ | |
0198230b PM |
190 | int __cookie_v4_check(const struct iphdr *iph, const struct tcphdr *th, |
191 | u32 cookie) | |
1da177e4 | 192 | { |
aa8223c7 ACM |
193 | __u32 seq = ntohl(th->seq) - 1; |
194 | __u32 mssind = check_tcp_syn_cookie(cookie, iph->saddr, iph->daddr, | |
8c27bd75 | 195 | th->source, th->dest, seq); |
1da177e4 | 196 | |
5918e2fb | 197 | return mssind < ARRAY_SIZE(msstab) ? msstab[mssind] : 0; |
1da177e4 | 198 | } |
0198230b | 199 | EXPORT_SYMBOL_GPL(__cookie_v4_check); |
1da177e4 | 200 | |
b80c0e78 ED |
201 | struct sock *tcp_get_cookie_sock(struct sock *sk, struct sk_buff *skb, |
202 | struct request_sock *req, | |
84b114b9 | 203 | struct dst_entry *dst, u32 tsoff) |
1da177e4 | 204 | { |
8292a17a | 205 | struct inet_connection_sock *icsk = inet_csk(sk); |
1da177e4 | 206 | struct sock *child; |
5e0724d0 | 207 | bool own_req; |
1da177e4 | 208 | |
5e0724d0 ED |
209 | child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst, |
210 | NULL, &own_req); | |
0470c8ca | 211 | if (child) { |
41c6d650 | 212 | refcount_set(&req->rsk_refcnt, 1); |
84b114b9 | 213 | tcp_sk(child)->tsoffset = tsoff; |
6bcfd7f8 | 214 | sock_rps_save_rxhash(child, skb); |
9466a1cc | 215 | |
0e8642cf | 216 | if (rsk_drop_req(req)) { |
9d8c05ad | 217 | reqsk_put(req); |
9466a1cc FW |
218 | return child; |
219 | } | |
220 | ||
9403cf23 GN |
221 | if (inet_csk_reqsk_queue_add(sk, req, child)) |
222 | return child; | |
223 | ||
224 | bh_unlock_sock(child); | |
225 | sock_put(child); | |
0470c8ca | 226 | } |
9403cf23 GN |
227 | __reqsk_free(req); |
228 | ||
229 | return NULL; | |
1da177e4 | 230 | } |
b80c0e78 | 231 | EXPORT_SYMBOL(tcp_get_cookie_sock); |
4dfc2817 FW |
232 | |
233 | /* | |
234 | * when syncookies are in effect and tcp timestamps are enabled we stored | |
235 | * additional tcp options in the timestamp. | |
236 | * This extracts these options from the timestamp echo. | |
237 | * | |
f1673381 FW |
238 | * return false if we decode a tcp option that is disabled |
239 | * on the host. | |
4dfc2817 | 240 | */ |
f9301034 ED |
241 | bool cookie_timestamp_decode(const struct net *net, |
242 | struct tcp_options_received *tcp_opt) | |
4dfc2817 | 243 | { |
734f614b | 244 | /* echoed timestamp, lowest bits contain options */ |
274e2da0 | 245 | u32 options = tcp_opt->rcv_tsecr; |
4dfc2817 | 246 | |
8c763681 FW |
247 | if (!tcp_opt->saw_tstamp) { |
248 | tcp_clear_options(tcp_opt); | |
249 | return true; | |
250 | } | |
251 | ||
5d2ed052 | 252 | if (!net->ipv4.sysctl_tcp_timestamps) |
8c763681 FW |
253 | return false; |
254 | ||
274e2da0 | 255 | tcp_opt->sack_ok = (options & TS_OPT_SACK) ? TCP_SACK_SEEN : 0; |
4dfc2817 | 256 | |
f9301034 | 257 | if (tcp_opt->sack_ok && !net->ipv4.sysctl_tcp_sack) |
8c763681 | 258 | return false; |
4dfc2817 | 259 | |
274e2da0 | 260 | if ((options & TS_OPT_WSCALE_MASK) == TS_OPT_WSCALE_MASK) |
734f614b FW |
261 | return true; /* no window scaling */ |
262 | ||
263 | tcp_opt->wscale_ok = 1; | |
274e2da0 FW |
264 | tcp_opt->snd_wscale = options & TS_OPT_WSCALE_MASK; |
265 | ||
9bb37ef0 | 266 | return net->ipv4.sysctl_tcp_window_scaling != 0; |
4dfc2817 | 267 | } |
f1673381 FW |
268 | EXPORT_SYMBOL(cookie_timestamp_decode); |
269 | ||
270 | bool cookie_ecn_ok(const struct tcp_options_received *tcp_opt, | |
f7b3bec6 | 271 | const struct net *net, const struct dst_entry *dst) |
f1673381 FW |
272 | { |
273 | bool ecn_ok = tcp_opt->rcv_tsecr & TS_OPT_ECN; | |
274 | ||
275 | if (!ecn_ok) | |
276 | return false; | |
277 | ||
278 | if (net->ipv4.sysctl_tcp_ecn) | |
279 | return true; | |
280 | ||
f7b3bec6 | 281 | return dst_feature(dst, RTAX_FEATURE_ECN); |
f1673381 FW |
282 | } |
283 | EXPORT_SYMBOL(cookie_ecn_ok); | |
4dfc2817 | 284 | |
6fc8c827 FW |
285 | struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops, |
286 | struct sock *sk, | |
287 | struct sk_buff *skb) | |
288 | { | |
e9b12edc | 289 | struct tcp_request_sock *treq; |
6fc8c827 FW |
290 | struct request_sock *req; |
291 | ||
292 | #ifdef CONFIG_MPTCP | |
293 | if (sk_is_mptcp(sk)) | |
294 | ops = &mptcp_subflow_request_sock_ops; | |
295 | #endif | |
296 | ||
297 | req = inet_reqsk_alloc(ops, sk, false); | |
298 | if (!req) | |
299 | return NULL; | |
300 | ||
6fc8c827 | 301 | treq = tcp_rsk(req); |
e9b12edc WW |
302 | treq->syn_tos = TCP_SKB_CB(skb)->ip_dsfield; |
303 | #if IS_ENABLED(CONFIG_MPTCP) | |
6fc8c827 FW |
304 | treq->is_mptcp = sk_is_mptcp(sk); |
305 | if (treq->is_mptcp) { | |
306 | int err = mptcp_subflow_init_cookie_req(req, sk, skb); | |
307 | ||
308 | if (err) { | |
309 | reqsk_free(req); | |
310 | return NULL; | |
311 | } | |
312 | } | |
313 | #endif | |
314 | ||
315 | return req; | |
316 | } | |
317 | EXPORT_SYMBOL_GPL(cookie_tcp_reqsk_alloc); | |
318 | ||
079096f1 ED |
319 | /* On input, sk is a listener. |
320 | * Output is listener if incoming packet would not create a child | |
321 | * NULL if memory could not be allocated. | |
322 | */ | |
461b74c3 | 323 | struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb) |
1da177e4 | 324 | { |
461b74c3 | 325 | struct ip_options *opt = &TCP_SKB_CB(skb)->header.h4.opt; |
4957faad | 326 | struct tcp_options_received tcp_opt; |
2e6599cb ACM |
327 | struct inet_request_sock *ireq; |
328 | struct tcp_request_sock *treq; | |
1da177e4 | 329 | struct tcp_sock *tp = tcp_sk(sk); |
aa8223c7 ACM |
330 | const struct tcphdr *th = tcp_hdr(skb); |
331 | __u32 cookie = ntohl(th->ack_seq) - 1; | |
1da177e4 | 332 | struct sock *ret = sk; |
e905a9ed | 333 | struct request_sock *req; |
909172a1 | 334 | int full_space, mss; |
e905a9ed | 335 | struct rtable *rt; |
1da177e4 | 336 | __u8 rcv_wscale; |
dfd25fff | 337 | struct flowi4 fl4; |
84b114b9 | 338 | u32 tsoff = 0; |
1da177e4 | 339 | |
12ed8244 | 340 | if (!sock_net(sk)->ipv4.sysctl_tcp_syncookies || !th->ack || th->rst) |
1da177e4 LT |
341 | goto out; |
342 | ||
646697b9 FW |
343 | if (tcp_synq_no_recent_overflow(sk)) |
344 | goto out; | |
345 | ||
346 | mss = __cookie_v4_check(ip_hdr(skb), th, cookie); | |
347 | if (mss == 0) { | |
02a1d6e7 | 348 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESFAILED); |
1da177e4 LT |
349 | goto out; |
350 | } | |
351 | ||
02a1d6e7 | 352 | __NET_INC_STATS(sock_net(sk), LINUX_MIB_SYNCOOKIESRECV); |
1da177e4 | 353 | |
bb5b7c11 DM |
354 | /* check for timestamp cookie support */ |
355 | memset(&tcp_opt, 0, sizeof(tcp_opt)); | |
eed29f17 | 356 | tcp_parse_options(sock_net(sk), skb, &tcp_opt, 0, NULL); |
bb5b7c11 | 357 | |
84b114b9 | 358 | if (tcp_opt.saw_tstamp && tcp_opt.rcv_tsecr) { |
5d2ed052 ED |
359 | tsoff = secure_tcp_ts_off(sock_net(sk), |
360 | ip_hdr(skb)->daddr, | |
361 | ip_hdr(skb)->saddr); | |
84b114b9 ED |
362 | tcp_opt.rcv_tsecr -= tsoff; |
363 | } | |
364 | ||
f9301034 | 365 | if (!cookie_timestamp_decode(sock_net(sk), &tcp_opt)) |
8c763681 | 366 | goto out; |
bb5b7c11 | 367 | |
1da177e4 | 368 | ret = NULL; |
6fc8c827 | 369 | req = cookie_tcp_reqsk_alloc(&tcp_request_sock_ops, sk, skb); |
1da177e4 LT |
370 | if (!req) |
371 | goto out; | |
372 | ||
2e6599cb ACM |
373 | ireq = inet_rsk(req); |
374 | treq = tcp_rsk(req); | |
aa8223c7 | 375 | treq->rcv_isn = ntohl(th->seq) - 1; |
e905a9ed | 376 | treq->snt_isn = cookie; |
95a22cae | 377 | treq->ts_off = 0; |
18bcf290 | 378 | treq->txhash = net_tx_rndhash(); |
1da177e4 | 379 | req->mss = mss; |
b44084c2 ED |
380 | ireq->ir_num = ntohs(th->dest); |
381 | ireq->ir_rmt_port = th->source; | |
08d2cc3b ED |
382 | sk_rcv_saddr_set(req_to_sk(req), ip_hdr(skb)->daddr); |
383 | sk_daddr_set(req_to_sk(req), ip_hdr(skb)->saddr); | |
84f39b08 | 384 | ireq->ir_mark = inet_request_mark(sk, skb); |
bb5b7c11 | 385 | ireq->snd_wscale = tcp_opt.snd_wscale; |
bb5b7c11 DM |
386 | ireq->sack_ok = tcp_opt.sack_ok; |
387 | ireq->wscale_ok = tcp_opt.wscale_ok; | |
388 | ireq->tstamp_ok = tcp_opt.saw_tstamp; | |
389 | req->ts_recent = tcp_opt.saw_tstamp ? tcp_opt.rcv_tsval : 0; | |
9a568de4 | 390 | treq->snt_synack = 0; |
9439ce00 | 391 | treq->tfo_listener = false; |
ae2dd716 | 392 | |
bc58a1ba HW |
393 | if (IS_ENABLED(CONFIG_SMC)) |
394 | ireq->smc_ok = 0; | |
1da177e4 | 395 | |
6dd9a14e | 396 | ireq->ir_iif = inet_request_bound_dev_if(sk, skb); |
16f86165 | 397 | |
1da177e4 LT |
398 | /* We throwed the options of the initial SYN away, so we hope |
399 | * the ACK carries the same options again (see RFC1122 4.2.3.8) | |
400 | */ | |
c92e8c02 | 401 | RCU_INIT_POINTER(ireq->ireq_opt, tcp_v4_save_options(sock_net(sk), skb)); |
1da177e4 | 402 | |
284904aa | 403 | if (security_inet_conn_request(sk, skb, req)) { |
0470c8ca | 404 | reqsk_free(req); |
284904aa PM |
405 | goto out; |
406 | } | |
407 | ||
e6c022a4 | 408 | req->num_retrans = 0; |
e905a9ed | 409 | |
1da177e4 LT |
410 | /* |
411 | * We need to lookup the route here to get at the correct | |
412 | * window size. We should better make sure that the window size | |
413 | * hasn't changed since we received the original syn, but I see | |
e905a9ed | 414 | * no easy way to do this. |
1da177e4 | 415 | */ |
6dd9a14e | 416 | flowi4_init_output(&fl4, ireq->ir_iif, ireq->ir_mark, |
d66954a0 | 417 | RT_CONN_FLAGS(sk), RT_SCOPE_UNIVERSE, IPPROTO_TCP, |
dfd25fff | 418 | inet_sk_flowi_flags(sk), |
461b74c3 | 419 | opt->srr ? opt->faddr : ireq->ir_rmt_addr, |
e2d118a1 | 420 | ireq->ir_loc_addr, th->source, th->dest, sk->sk_uid); |
3df98d79 | 421 | security_req_classify_flow(req, flowi4_to_flowi_common(&fl4)); |
dfd25fff ED |
422 | rt = ip_route_output_key(sock_net(sk), &fl4); |
423 | if (IS_ERR(rt)) { | |
0470c8ca | 424 | reqsk_free(req); |
dfd25fff | 425 | goto out; |
1da177e4 LT |
426 | } |
427 | ||
428 | /* Try to redo what tcp_v4_send_synack did. */ | |
ed53d0ab | 429 | req->rsk_window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW); |
909172a1 MW |
430 | /* limit the window selection if the user enforce a smaller rx buffer */ |
431 | full_space = tcp_full_space(sk); | |
432 | if (sk->sk_userlocks & SOCK_RCVBUF_LOCK && | |
433 | (req->rsk_window_clamp > full_space || req->rsk_window_clamp == 0)) | |
434 | req->rsk_window_clamp = full_space; | |
4dfc2817 | 435 | |
909172a1 | 436 | tcp_select_initial_window(sk, full_space, req->mss, |
ed53d0ab | 437 | &req->rsk_rcv_wnd, &req->rsk_window_clamp, |
31d12926 | 438 | ireq->wscale_ok, &rcv_wscale, |
d8d1f30b | 439 | dst_metric(&rt->dst, RTAX_INITRWND)); |
4dfc2817 | 440 | |
e905a9ed | 441 | ireq->rcv_wscale = rcv_wscale; |
f7b3bec6 | 442 | ireq->ecn_ok = cookie_ecn_ok(&tcp_opt, sock_net(sk), &rt->dst); |
1da177e4 | 443 | |
84b114b9 | 444 | ret = tcp_get_cookie_sock(sk, skb, req, &rt->dst, tsoff); |
dfd25fff ED |
445 | /* ip_queue_xmit() depends on our flow being setup |
446 | * Normal sockets get it right from inet_csk_route_child_sock() | |
447 | */ | |
448 | if (ret) | |
449 | inet_sk(ret)->cork.fl.u.ip4 = fl4; | |
1da177e4 LT |
450 | out: return ret; |
451 | } |