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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * Syncookies implementation for the Linux kernel
3 *
4 * Copyright (C) 1997 Andi Kleen
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +09005 * Based on ideas by D.J.Bernstein and Eric Schenk.
Linus Torvalds1da177e2005-04-16 15:20:36 -07006 *
7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version.
Linus Torvalds1da177e2005-04-16 15:20:36 -070011 */
12
13#include <linux/tcp.h>
14#include <linux/slab.h>
15#include <linux/random.h>
16#include <linux/cryptohash.h>
17#include <linux/kernel.h>
Paul Gortmakerbc3b2d72011-07-15 11:47:34 -040018#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070019#include <net/tcp.h>
KOVACS Krisztian86b08d82008-10-01 07:44:42 -070020#include <net/route.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070021
Florian Westphal734f6142010-06-21 11:48:44 +000022/* Timestamps: lowest bits store TCP options */
Florian Westphal172d69e2010-06-21 11:48:45 +000023#define TSBITS 6
Florian Westphal4dfc2812008-04-10 03:12:40 -070024#define TSMASK (((__u32)1 << TSBITS) - 1)
25
Linus Torvalds1da177e2005-04-16 15:20:36 -070026extern int sysctl_tcp_syncookies;
27
Florian Westphal2051f112008-03-23 22:21:28 -070028__u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
Glenn Griffinc6aefaf2008-02-07 21:49:26 -080029EXPORT_SYMBOL(syncookie_secret);
Linus Torvalds1da177e2005-04-16 15:20:36 -070030
31static __init int init_syncookies(void)
32{
33 get_random_bytes(syncookie_secret, sizeof(syncookie_secret));
34 return 0;
35}
Glenn Griffinc6aefaf2008-02-07 21:49:26 -080036__initcall(init_syncookies);
Linus Torvalds1da177e2005-04-16 15:20:36 -070037
38#define COOKIEBITS 24 /* Upper bits store count */
39#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
40
Tejun Heo245b2e72009-06-24 15:13:48 +090041static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS],
42 ipv4_cookie_scratch);
Eric Dumazet11baab72008-02-07 10:40:19 +010043
Al Viro714e85b2006-11-14 20:51:49 -080044static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
Linus Torvalds1da177e2005-04-16 15:20:36 -070045 u32 count, int c)
46{
Tejun Heo245b2e72009-06-24 15:13:48 +090047 __u32 *tmp = __get_cpu_var(ipv4_cookie_scratch);
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
Florian Westphal2051f112008-03-23 22:21:28 -070049 memcpy(tmp + 4, syncookie_secret[c], sizeof(syncookie_secret[c]));
Al Viro714e85b2006-11-14 20:51:49 -080050 tmp[0] = (__force u32)saddr;
51 tmp[1] = (__force u32)daddr;
52 tmp[2] = ((__force u32)sport << 16) + (__force u32)dport;
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 tmp[3] = count;
54 sha_transform(tmp + 16, (__u8 *)tmp, tmp + 16 + 5);
55
56 return tmp[17];
57}
58
Florian Westphal4dfc2812008-04-10 03:12:40 -070059
60/*
61 * when syncookies are in effect and tcp timestamps are enabled we encode
Florian Westphal734f6142010-06-21 11:48:44 +000062 * tcp options in the lower bits of the timestamp value that will be
Florian Westphal4dfc2812008-04-10 03:12:40 -070063 * sent in the syn-ack.
64 * Since subsequent timestamps use the normal tcp_time_stamp value, we
65 * must make sure that the resulting initial timestamp is <= tcp_time_stamp.
66 */
67__u32 cookie_init_timestamp(struct request_sock *req)
68{
69 struct inet_request_sock *ireq;
70 u32 ts, ts_now = tcp_time_stamp;
71 u32 options = 0;
72
73 ireq = inet_rsk(req);
Florian Westphal734f6142010-06-21 11:48:44 +000074
75 options = ireq->wscale_ok ? ireq->snd_wscale : 0xf;
76 options |= ireq->sack_ok << 4;
Florian Westphal172d69e2010-06-21 11:48:45 +000077 options |= ireq->ecn_ok << 5;
Florian Westphal4dfc2812008-04-10 03:12:40 -070078
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 }
87 return ts;
88}
89
90
Al Viro714e85b2006-11-14 20:51:49 -080091static __u32 secure_tcp_syn_cookie(__be32 saddr, __be32 daddr, __be16 sport,
92 __be16 dport, __u32 sseq, __u32 count,
Linus Torvalds1da177e2005-04-16 15:20:36 -070093 __u32 data)
94{
95 /*
96 * Compute the secure sequence number.
97 * The output should be:
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +090098 * HASH(sec1,saddr,sport,daddr,dport,sec1) + sseq + (count * 2^24)
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 * + (HASH(sec2,saddr,sport,daddr,dport,count,sec2) % 2^24).
100 * Where sseq is their sequence number and count increases every
101 * minute by 1.
102 * As an extra hack, we add a small "data" value that encodes the
103 * MSS into the second hash value.
104 */
105
106 return (cookie_hash(saddr, daddr, sport, dport, 0, 0) +
107 sseq + (count << COOKIEBITS) +
108 ((cookie_hash(saddr, daddr, sport, dport, count, 1) + data)
109 & COOKIEMASK));
110}
111
112/*
113 * This retrieves the small "data" value from the syncookie.
114 * If the syncookie is bad, the data returned will be out of
115 * range. This must be checked by the caller.
116 *
117 * The count value used to generate the cookie must be within
118 * "maxdiff" if the current (passed-in) "count". The return value
119 * is (__u32)-1 if this test fails.
120 */
Al Viro714e85b2006-11-14 20:51:49 -0800121static __u32 check_tcp_syn_cookie(__u32 cookie, __be32 saddr, __be32 daddr,
122 __be16 sport, __be16 dport, __u32 sseq,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700123 __u32 count, __u32 maxdiff)
124{
125 __u32 diff;
126
127 /* Strip away the layers from the cookie */
128 cookie -= cookie_hash(saddr, daddr, sport, dport, 0, 0) + sseq;
129
130 /* Cookie is now reduced to (count * 2^24) ^ (hash % 2^24) */
131 diff = (count - (cookie >> COOKIEBITS)) & ((__u32) - 1 >> COOKIEBITS);
132 if (diff >= maxdiff)
133 return (__u32)-1;
134
135 return (cookie -
136 cookie_hash(saddr, daddr, sport, dport, count - diff, 1))
137 & COOKIEMASK; /* Leaving the data behind */
138}
139
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900140/*
Florian Westphal5918e2f2010-06-03 00:43:57 +0000141 * MSS Values are taken from the 2009 paper
142 * 'Measuring TCP Maximum Segment Size' by S. Alcock and R. Nelson:
143 * - values 1440 to 1460 accounted for 80% of observed mss values
144 * - values outside the 536-1460 range are rare (<0.2%).
145 *
146 * Table must be sorted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700147 */
148static __u16 const msstab[] = {
Florian Westphal5918e2f2010-06-03 00:43:57 +0000149 64,
150 512,
151 536,
152 1024,
153 1440,
154 1460,
155 4312,
156 8960,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700158
159/*
160 * Generate a syncookie. mssp points to the mss, which is returned
161 * rounded down to the value encoded in the cookie.
162 */
163__u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp)
164{
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700165 const struct iphdr *iph = ip_hdr(skb);
166 const struct tcphdr *th = tcp_hdr(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167 int mssind;
168 const __u16 mss = *mssp;
169
Florian Westphala0f82f62009-04-19 09:43:48 +0000170 tcp_synq_overflow(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700171
Florian Westphal5918e2f2010-06-03 00:43:57 +0000172 for (mssind = ARRAY_SIZE(msstab) - 1; mssind ; mssind--)
173 if (mss >= msstab[mssind])
174 break;
175 *mssp = msstab[mssind];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700176
Pavel Emelyanovde0744a2008-07-16 20:31:16 -0700177 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700179 return secure_tcp_syn_cookie(iph->saddr, iph->daddr,
180 th->source, th->dest, ntohl(th->seq),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700181 jiffies / (HZ * 60), mssind);
182}
183
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900184/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700185 * This (misnamed) value is the age of syncookie which is permitted.
186 * Its ideal value should be dependent on TCP_TIMEOUT_INIT and
187 * sysctl_tcp_retries1. It's a rather complicated formula (exponential
188 * backoff) to compute at runtime so it's currently hardcoded here.
189 */
190#define COUNTER_TRIES 4
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900191/*
192 * Check if a ack sequence number is a valid syncookie.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 * Return the decoded mss if it is, or 0 if not.
194 */
195static inline int cookie_check(struct sk_buff *skb, __u32 cookie)
196{
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700197 const struct iphdr *iph = ip_hdr(skb);
198 const struct tcphdr *th = tcp_hdr(skb);
199 __u32 seq = ntohl(th->seq) - 1;
200 __u32 mssind = check_tcp_syn_cookie(cookie, iph->saddr, iph->daddr,
201 th->source, th->dest, seq,
202 jiffies / (HZ * 60),
203 COUNTER_TRIES);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204
Florian Westphal5918e2f2010-06-03 00:43:57 +0000205 return mssind < ARRAY_SIZE(msstab) ? msstab[mssind] : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700206}
207
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
Arnaldo Carvalho de Melo60236fd2005-06-18 22:47:21 -0700209 struct request_sock *req,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700210 struct dst_entry *dst)
211{
Arnaldo Carvalho de Melo8292a172005-12-13 23:15:52 -0800212 struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700213 struct sock *child;
214
Arnaldo Carvalho de Melo8292a172005-12-13 23:15:52 -0800215 child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216 if (child)
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700217 inet_csk_reqsk_queue_add(sk, req, child);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218 else
Arnaldo Carvalho de Melo60236fd2005-06-18 22:47:21 -0700219 reqsk_free(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220
221 return child;
222}
223
Florian Westphal4dfc2812008-04-10 03:12:40 -0700224
225/*
226 * when syncookies are in effect and tcp timestamps are enabled we stored
227 * additional tcp options in the timestamp.
228 * This extracts these options from the timestamp echo.
229 *
Florian Westphal734f6142010-06-21 11:48:44 +0000230 * The lowest 4 bits store snd_wscale.
Florian Westphal172d69e2010-06-21 11:48:45 +0000231 * next 2 bits indicate SACK and ECN support.
Florian Westphal8c763682010-06-16 14:42:15 -0700232 *
233 * return false if we decode an option that should not be.
Florian Westphal4dfc2812008-04-10 03:12:40 -0700234 */
Florian Westphal172d69e2010-06-21 11:48:45 +0000235bool cookie_check_timestamp(struct tcp_options_received *tcp_opt, bool *ecn_ok)
Florian Westphal4dfc2812008-04-10 03:12:40 -0700236{
Florian Westphal734f6142010-06-21 11:48:44 +0000237 /* echoed timestamp, lowest bits contain options */
Florian Westphal4dfc2812008-04-10 03:12:40 -0700238 u32 options = tcp_opt->rcv_tsecr & TSMASK;
239
Florian Westphal8c763682010-06-16 14:42:15 -0700240 if (!tcp_opt->saw_tstamp) {
241 tcp_clear_options(tcp_opt);
242 return true;
243 }
244
245 if (!sysctl_tcp_timestamps)
246 return false;
247
Vijay Subramanianab562222011-12-20 13:23:24 +0000248 tcp_opt->sack_ok = (options & (1 << 4)) ? TCP_SACK_SEEN : 0;
Florian Westphal172d69e2010-06-21 11:48:45 +0000249 *ecn_ok = (options >> 5) & 1;
250 if (*ecn_ok && !sysctl_tcp_ecn)
251 return false;
Florian Westphal4dfc2812008-04-10 03:12:40 -0700252
Florian Westphal8c763682010-06-16 14:42:15 -0700253 if (tcp_opt->sack_ok && !sysctl_tcp_sack)
254 return false;
Florian Westphal4dfc2812008-04-10 03:12:40 -0700255
Florian Westphal734f6142010-06-21 11:48:44 +0000256 if ((options & 0xf) == 0xf)
257 return true; /* no window scaling */
258
259 tcp_opt->wscale_ok = 1;
260 tcp_opt->snd_wscale = options & 0xf;
261 return sysctl_tcp_window_scaling != 0;
Florian Westphal4dfc2812008-04-10 03:12:40 -0700262}
263EXPORT_SYMBOL(cookie_check_timestamp);
264
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
266 struct ip_options *opt)
267{
William Allen Simpson4957faa2009-12-02 18:25:27 +0000268 struct tcp_options_received tcp_opt;
Eric Dumazetcf533ea2011-10-21 05:22:42 -0400269 const u8 *hash_location;
Arnaldo Carvalho de Melo2e6599c2005-06-18 22:46:52 -0700270 struct inet_request_sock *ireq;
271 struct tcp_request_sock *treq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700272 struct tcp_sock *tp = tcp_sk(sk);
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700273 const struct tcphdr *th = tcp_hdr(skb);
274 __u32 cookie = ntohl(th->ack_seq) - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700275 struct sock *ret = sk;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900276 struct request_sock *req;
277 int mss;
278 struct rtable *rt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700279 __u8 rcv_wscale;
Mike Waychisonf0e3d062011-08-10 21:59:57 -0700280 bool ecn_ok = false;
Eric Dumazetdfd25ff2012-03-10 09:20:21 +0000281 struct flowi4 fl4;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282
Florian Westphalaf9b4732010-06-03 00:43:44 +0000283 if (!sysctl_tcp_syncookies || !th->ack || th->rst)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700284 goto out;
285
Florian Westphala0f82f62009-04-19 09:43:48 +0000286 if (tcp_synq_no_recent_overflow(sk) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 (mss = cookie_check(skb, cookie)) == 0) {
Pavel Emelyanovde0744a2008-07-16 20:31:16 -0700288 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESFAILED);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 goto out;
290 }
291
Pavel Emelyanovde0744a2008-07-16 20:31:16 -0700292 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESRECV);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700293
David S. Millerbb5b7c12009-12-15 20:56:42 -0800294 /* check for timestamp cookie support */
295 memset(&tcp_opt, 0, sizeof(tcp_opt));
296 tcp_parse_options(skb, &tcp_opt, &hash_location, 0);
297
Florian Westphal172d69e2010-06-21 11:48:45 +0000298 if (!cookie_check_timestamp(&tcp_opt, &ecn_ok))
Florian Westphal8c763682010-06-16 14:42:15 -0700299 goto out;
David S. Millerbb5b7c12009-12-15 20:56:42 -0800300
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 ret = NULL;
Arnaldo Carvalho de Meloce4a7d02008-06-10 12:39:35 -0700302 req = inet_reqsk_alloc(&tcp_request_sock_ops); /* for safety */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700303 if (!req)
304 goto out;
305
Arnaldo Carvalho de Melo2e6599c2005-06-18 22:46:52 -0700306 ireq = inet_rsk(req);
307 treq = tcp_rsk(req);
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700308 treq->rcv_isn = ntohl(th->seq) - 1;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900309 treq->snt_isn = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700310 req->mss = mss;
KOVACS Krisztiana3116ac2008-10-01 07:46:49 -0700311 ireq->loc_port = th->dest;
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700312 ireq->rmt_port = th->source;
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700313 ireq->loc_addr = ip_hdr(skb)->daddr;
314 ireq->rmt_addr = ip_hdr(skb)->saddr;
Florian Westphal172d69e2010-06-21 11:48:45 +0000315 ireq->ecn_ok = ecn_ok;
David S. Millerbb5b7c12009-12-15 20:56:42 -0800316 ireq->snd_wscale = tcp_opt.snd_wscale;
David S. Millerbb5b7c12009-12-15 20:56:42 -0800317 ireq->sack_ok = tcp_opt.sack_ok;
318 ireq->wscale_ok = tcp_opt.wscale_ok;
319 ireq->tstamp_ok = tcp_opt.saw_tstamp;
320 req->ts_recent = tcp_opt.saw_tstamp ? tcp_opt.rcv_tsval : 0;
Jerry Chu9ad7c042011-06-08 11:08:38 +0000321 treq->snt_synack = tcp_opt.saw_tstamp ? tcp_opt.rcv_tsecr : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700322
323 /* We throwed the options of the initial SYN away, so we hope
324 * the ACK carries the same options again (see RFC1122 4.2.3.8)
325 */
326 if (opt && opt->optlen) {
Eric Dumazetf6d8bd02011-04-21 09:45:37 +0000327 int opt_size = sizeof(struct ip_options_rcu) + opt->optlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700328
Arnaldo Carvalho de Melo2e6599c2005-06-18 22:46:52 -0700329 ireq->opt = kmalloc(opt_size, GFP_ATOMIC);
Eric Dumazetf6d8bd02011-04-21 09:45:37 +0000330 if (ireq->opt != NULL && ip_options_echo(&ireq->opt->opt, skb)) {
Arnaldo Carvalho de Melo2e6599c2005-06-18 22:46:52 -0700331 kfree(ireq->opt);
332 ireq->opt = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333 }
334 }
335
Paul Moore284904a2009-03-27 17:10:28 -0400336 if (security_inet_conn_request(sk, skb, req)) {
337 reqsk_free(req);
338 goto out;
339 }
340
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900341 req->expires = 0UL;
342 req->retrans = 0;
343
Linus Torvalds1da177e2005-04-16 15:20:36 -0700344 /*
345 * We need to lookup the route here to get at the correct
346 * window size. We should better make sure that the window size
347 * hasn't changed since we received the original syn, but I see
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900348 * no easy way to do this.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 */
Eric Dumazetdfd25ff2012-03-10 09:20:21 +0000350 flowi4_init_output(&fl4, 0, sk->sk_mark, RT_CONN_FLAGS(sk),
351 RT_SCOPE_UNIVERSE, IPPROTO_TCP,
352 inet_sk_flowi_flags(sk),
353 (opt && opt->srr) ? opt->faddr : ireq->rmt_addr,
354 ireq->loc_addr, th->source, th->dest);
355 security_req_classify_flow(req, flowi4_to_flowi(&fl4));
356 rt = ip_route_output_key(sock_net(sk), &fl4);
357 if (IS_ERR(rt)) {
358 reqsk_free(req);
359 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700360 }
361
362 /* Try to redo what tcp_v4_send_synack did. */
Changli Gaod8d1f302010-06-10 23:31:35 -0700363 req->window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW);
Florian Westphal4dfc2812008-04-10 03:12:40 -0700364
Linus Torvalds1da177e2005-04-16 15:20:36 -0700365 tcp_select_initial_window(tcp_full_space(sk), req->mss,
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900366 &req->rcv_wnd, &req->window_clamp,
laurent chavey31d12922009-12-15 11:15:28 +0000367 ireq->wscale_ok, &rcv_wscale,
Changli Gaod8d1f302010-06-10 23:31:35 -0700368 dst_metric(&rt->dst, RTAX_INITRWND));
Florian Westphal4dfc2812008-04-10 03:12:40 -0700369
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900370 ireq->rcv_wscale = rcv_wscale;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700371
Changli Gaod8d1f302010-06-10 23:31:35 -0700372 ret = get_cookie_sock(sk, skb, req, &rt->dst);
Eric Dumazetdfd25ff2012-03-10 09:20:21 +0000373 /* ip_queue_xmit() depends on our flow being setup
374 * Normal sockets get it right from inet_csk_route_child_sock()
375 */
376 if (ret)
377 inet_sk(ret)->cork.fl.u.ip4 = fl4;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378out: return ret;
379}