blob: 92bb9434b338d0064becad817e2aaf96f402870d [file] [log] [blame]
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>
18#include <net/tcp.h>
KOVACS Krisztian86b08d82008-10-01 07:44:42 -070019#include <net/route.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020
Florian Westphal734f6142010-06-21 11:48:44 +000021/* Timestamps: lowest bits store TCP options */
Florian Westphal172d69e2010-06-21 11:48:45 +000022#define TSBITS 6
Florian Westphal4dfc2812008-04-10 03:12:40 -070023#define TSMASK (((__u32)1 << TSBITS) - 1)
24
Linus Torvalds1da177e2005-04-16 15:20:36 -070025extern int sysctl_tcp_syncookies;
26
Florian Westphal2051f112008-03-23 22:21:28 -070027__u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
Glenn Griffinc6aefaf2008-02-07 21:49:26 -080028EXPORT_SYMBOL(syncookie_secret);
Linus Torvalds1da177e2005-04-16 15:20:36 -070029
30static __init int init_syncookies(void)
31{
32 get_random_bytes(syncookie_secret, sizeof(syncookie_secret));
33 return 0;
34}
Glenn Griffinc6aefaf2008-02-07 21:49:26 -080035__initcall(init_syncookies);
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
37#define COOKIEBITS 24 /* Upper bits store count */
38#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)
39
Tejun Heo245b2e72009-06-24 15:13:48 +090040static DEFINE_PER_CPU(__u32 [16 + 5 + SHA_WORKSPACE_WORDS],
41 ipv4_cookie_scratch);
Eric Dumazet11baab72008-02-07 10:40:19 +010042
Al Viro714e85b2006-11-14 20:51:49 -080043static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
Linus Torvalds1da177e2005-04-16 15:20:36 -070044 u32 count, int c)
45{
Tejun Heo245b2e72009-06-24 15:13:48 +090046 __u32 *tmp = __get_cpu_var(ipv4_cookie_scratch);
Linus Torvalds1da177e2005-04-16 15:20:36 -070047
Florian Westphal2051f112008-03-23 22:21:28 -070048 memcpy(tmp + 4, syncookie_secret[c], sizeof(syncookie_secret[c]));
Al Viro714e85b2006-11-14 20:51:49 -080049 tmp[0] = (__force u32)saddr;
50 tmp[1] = (__force u32)daddr;
51 tmp[2] = ((__force u32)sport << 16) + (__force u32)dport;
Linus Torvalds1da177e2005-04-16 15:20:36 -070052 tmp[3] = count;
53 sha_transform(tmp + 16, (__u8 *)tmp, tmp + 16 + 5);
54
55 return tmp[17];
56}
57
Florian Westphal4dfc2812008-04-10 03:12:40 -070058
59/*
60 * when syncookies are in effect and tcp timestamps are enabled we encode
Florian Westphal734f6142010-06-21 11:48:44 +000061 * tcp options in the lower bits of the timestamp value that will be
Florian Westphal4dfc2812008-04-10 03:12:40 -070062 * sent in the syn-ack.
63 * Since subsequent timestamps use the normal tcp_time_stamp value, we
64 * must make sure that the resulting initial timestamp is <= tcp_time_stamp.
65 */
66__u32 cookie_init_timestamp(struct request_sock *req)
67{
68 struct inet_request_sock *ireq;
69 u32 ts, ts_now = tcp_time_stamp;
70 u32 options = 0;
71
72 ireq = inet_rsk(req);
Florian Westphal734f6142010-06-21 11:48:44 +000073
74 options = ireq->wscale_ok ? ireq->snd_wscale : 0xf;
75 options |= ireq->sack_ok << 4;
Florian Westphal172d69e2010-06-21 11:48:45 +000076 options |= ireq->ecn_ok << 5;
Florian Westphal4dfc2812008-04-10 03:12:40 -070077
78 ts = ts_now & ~TSMASK;
79 ts |= options;
80 if (ts > ts_now) {
81 ts >>= TSBITS;
82 ts--;
83 ts <<= TSBITS;
84 ts |= options;
85 }
86 return ts;
87}
88
89
Al Viro714e85b2006-11-14 20:51:49 -080090static __u32 secure_tcp_syn_cookie(__be32 saddr, __be32 daddr, __be16 sport,
91 __be16 dport, __u32 sseq, __u32 count,
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 __u32 data)
93{
94 /*
95 * Compute the secure sequence number.
96 * The output should be:
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +090097 * HASH(sec1,saddr,sport,daddr,dport,sec1) + sseq + (count * 2^24)
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 * + (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 */
104
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 *
116 * The count value used to generate the cookie must be within
117 * "maxdiff" if the current (passed-in) "count". The return value
118 * is (__u32)-1 if this test fails.
119 */
Al Viro714e85b2006-11-14 20:51:49 -0800120static __u32 check_tcp_syn_cookie(__u32 cookie, __be32 saddr, __be32 daddr,
121 __be16 sport, __be16 dport, __u32 sseq,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700122 __u32 count, __u32 maxdiff)
123{
124 __u32 diff;
125
126 /* Strip away the layers from the cookie */
127 cookie -= cookie_hash(saddr, daddr, sport, dport, 0, 0) + sseq;
128
129 /* Cookie is now reduced to (count * 2^24) ^ (hash % 2^24) */
130 diff = (count - (cookie >> COOKIEBITS)) & ((__u32) - 1 >> COOKIEBITS);
131 if (diff >= maxdiff)
132 return (__u32)-1;
133
134 return (cookie -
135 cookie_hash(saddr, daddr, sport, dport, count - diff, 1))
136 & COOKIEMASK; /* Leaving the data behind */
137}
138
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900139/*
Florian Westphal5918e2f2010-06-03 00:43:57 +0000140 * MSS Values are taken from the 2009 paper
141 * 'Measuring TCP Maximum Segment Size' by S. Alcock and R. Nelson:
142 * - values 1440 to 1460 accounted for 80% of observed mss values
143 * - values outside the 536-1460 range are rare (<0.2%).
144 *
145 * Table must be sorted.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 */
147static __u16 const msstab[] = {
Florian Westphal5918e2f2010-06-03 00:43:57 +0000148 64,
149 512,
150 536,
151 1024,
152 1440,
153 1460,
154 4312,
155 8960,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700156};
Linus Torvalds1da177e2005-04-16 15:20:36 -0700157
158/*
159 * Generate a syncookie. mssp points to the mss, which is returned
160 * rounded down to the value encoded in the cookie.
161 */
162__u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp)
163{
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700164 const struct iphdr *iph = ip_hdr(skb);
165 const struct tcphdr *th = tcp_hdr(skb);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700166 int mssind;
167 const __u16 mss = *mssp;
168
Florian Westphala0f82f62009-04-19 09:43:48 +0000169 tcp_synq_overflow(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700170
Florian Westphal5918e2f2010-06-03 00:43:57 +0000171 for (mssind = ARRAY_SIZE(msstab) - 1; mssind ; mssind--)
172 if (mss >= msstab[mssind])
173 break;
174 *mssp = msstab[mssind];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175
Pavel Emelyanovde0744a2008-07-16 20:31:16 -0700176 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESSENT);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700177
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700178 return secure_tcp_syn_cookie(iph->saddr, iph->daddr,
179 th->source, th->dest, ntohl(th->seq),
Linus Torvalds1da177e2005-04-16 15:20:36 -0700180 jiffies / (HZ * 60), mssind);
181}
182
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900183/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700184 * This (misnamed) value is the age of syncookie which is permitted.
185 * Its ideal value should be dependent on TCP_TIMEOUT_INIT and
186 * sysctl_tcp_retries1. It's a rather complicated formula (exponential
187 * backoff) to compute at runtime so it's currently hardcoded here.
188 */
189#define COUNTER_TRIES 4
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900190/*
191 * Check if a ack sequence number is a valid syncookie.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 * Return the decoded mss if it is, or 0 if not.
193 */
194static inline int cookie_check(struct sk_buff *skb, __u32 cookie)
195{
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700196 const struct iphdr *iph = ip_hdr(skb);
197 const struct tcphdr *th = tcp_hdr(skb);
198 __u32 seq = ntohl(th->seq) - 1;
199 __u32 mssind = check_tcp_syn_cookie(cookie, iph->saddr, iph->daddr,
200 th->source, th->dest, seq,
201 jiffies / (HZ * 60),
202 COUNTER_TRIES);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203
Florian Westphal5918e2f2010-06-03 00:43:57 +0000204 return mssind < ARRAY_SIZE(msstab) ? msstab[mssind] : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205}
206
Linus Torvalds1da177e2005-04-16 15:20:36 -0700207static inline struct sock *get_cookie_sock(struct sock *sk, struct sk_buff *skb,
Arnaldo Carvalho de Melo60236fd2005-06-18 22:47:21 -0700208 struct request_sock *req,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700209 struct dst_entry *dst)
210{
Arnaldo Carvalho de Melo8292a172005-12-13 23:15:52 -0800211 struct inet_connection_sock *icsk = inet_csk(sk);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700212 struct sock *child;
213
Arnaldo Carvalho de Melo8292a172005-12-13 23:15:52 -0800214 child = icsk->icsk_af_ops->syn_recv_sock(sk, skb, req, dst);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700215 if (child)
Arnaldo Carvalho de Melo463c84b2005-08-09 20:10:42 -0700216 inet_csk_reqsk_queue_add(sk, req, child);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 else
Arnaldo Carvalho de Melo60236fd2005-06-18 22:47:21 -0700218 reqsk_free(req);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700219
220 return child;
221}
222
Florian Westphal4dfc2812008-04-10 03:12:40 -0700223
224/*
225 * when syncookies are in effect and tcp timestamps are enabled we stored
226 * additional tcp options in the timestamp.
227 * This extracts these options from the timestamp echo.
228 *
Florian Westphal734f6142010-06-21 11:48:44 +0000229 * The lowest 4 bits store snd_wscale.
Florian Westphal172d69e2010-06-21 11:48:45 +0000230 * next 2 bits indicate SACK and ECN support.
Florian Westphal8c763682010-06-16 14:42:15 -0700231 *
232 * return false if we decode an option that should not be.
Florian Westphal4dfc2812008-04-10 03:12:40 -0700233 */
Florian Westphal172d69e2010-06-21 11:48:45 +0000234bool cookie_check_timestamp(struct tcp_options_received *tcp_opt, bool *ecn_ok)
Florian Westphal4dfc2812008-04-10 03:12:40 -0700235{
Florian Westphal734f6142010-06-21 11:48:44 +0000236 /* echoed timestamp, lowest bits contain options */
Florian Westphal4dfc2812008-04-10 03:12:40 -0700237 u32 options = tcp_opt->rcv_tsecr & TSMASK;
238
Florian Westphal8c763682010-06-16 14:42:15 -0700239 if (!tcp_opt->saw_tstamp) {
240 tcp_clear_options(tcp_opt);
241 return true;
242 }
243
244 if (!sysctl_tcp_timestamps)
245 return false;
246
Florian Westphal4dfc2812008-04-10 03:12:40 -0700247 tcp_opt->sack_ok = (options >> 4) & 0x1;
Florian Westphal172d69e2010-06-21 11:48:45 +0000248 *ecn_ok = (options >> 5) & 1;
249 if (*ecn_ok && !sysctl_tcp_ecn)
250 return false;
Florian Westphal4dfc2812008-04-10 03:12:40 -0700251
Florian Westphal8c763682010-06-16 14:42:15 -0700252 if (tcp_opt->sack_ok && !sysctl_tcp_sack)
253 return false;
Florian Westphal4dfc2812008-04-10 03:12:40 -0700254
Florian Westphal734f6142010-06-21 11:48:44 +0000255 if ((options & 0xf) == 0xf)
256 return true; /* no window scaling */
257
258 tcp_opt->wscale_ok = 1;
259 tcp_opt->snd_wscale = options & 0xf;
260 return sysctl_tcp_window_scaling != 0;
Florian Westphal4dfc2812008-04-10 03:12:40 -0700261}
262EXPORT_SYMBOL(cookie_check_timestamp);
263
Linus Torvalds1da177e2005-04-16 15:20:36 -0700264struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
265 struct ip_options *opt)
266{
William Allen Simpson4957faade2009-12-02 18:25:27 +0000267 struct tcp_options_received tcp_opt;
268 u8 *hash_location;
Arnaldo Carvalho de Melo2e6599c2005-06-18 22:46:52 -0700269 struct inet_request_sock *ireq;
270 struct tcp_request_sock *treq;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700271 struct tcp_sock *tp = tcp_sk(sk);
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700272 const struct tcphdr *th = tcp_hdr(skb);
273 __u32 cookie = ntohl(th->ack_seq) - 1;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700274 struct sock *ret = sk;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900275 struct request_sock *req;
276 int mss;
277 struct rtable *rt;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 __u8 rcv_wscale;
Florian Westphal172d69e2010-06-21 11:48:45 +0000279 bool ecn_ok;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700280
Florian Westphalaf9b4732010-06-03 00:43:44 +0000281 if (!sysctl_tcp_syncookies || !th->ack || th->rst)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700282 goto out;
283
Florian Westphala0f82f62009-04-19 09:43:48 +0000284 if (tcp_synq_no_recent_overflow(sk) ||
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 (mss = cookie_check(skb, cookie)) == 0) {
Pavel Emelyanovde0744a2008-07-16 20:31:16 -0700286 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESFAILED);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700287 goto out;
288 }
289
Pavel Emelyanovde0744a2008-07-16 20:31:16 -0700290 NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_SYNCOOKIESRECV);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700291
David S. Millerbb5b7c12009-12-15 20:56:42 -0800292 /* check for timestamp cookie support */
293 memset(&tcp_opt, 0, sizeof(tcp_opt));
294 tcp_parse_options(skb, &tcp_opt, &hash_location, 0);
295
Florian Westphal172d69e2010-06-21 11:48:45 +0000296 if (!cookie_check_timestamp(&tcp_opt, &ecn_ok))
Florian Westphal8c763682010-06-16 14:42:15 -0700297 goto out;
David S. Millerbb5b7c12009-12-15 20:56:42 -0800298
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 ret = NULL;
Arnaldo Carvalho de Meloce4a7d02008-06-10 12:39:35 -0700300 req = inet_reqsk_alloc(&tcp_request_sock_ops); /* for safety */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700301 if (!req)
302 goto out;
303
Arnaldo Carvalho de Melo2e6599c2005-06-18 22:46:52 -0700304 ireq = inet_rsk(req);
305 treq = tcp_rsk(req);
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700306 treq->rcv_isn = ntohl(th->seq) - 1;
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900307 treq->snt_isn = cookie;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700308 req->mss = mss;
KOVACS Krisztiana3116ac52008-10-01 07:46:49 -0700309 ireq->loc_port = th->dest;
Arnaldo Carvalho de Meloaa8223c2007-04-10 21:04:22 -0700310 ireq->rmt_port = th->source;
Arnaldo Carvalho de Meloeddc9ec2007-04-20 22:47:35 -0700311 ireq->loc_addr = ip_hdr(skb)->daddr;
312 ireq->rmt_addr = ip_hdr(skb)->saddr;
Florian Westphal172d69e2010-06-21 11:48:45 +0000313 ireq->ecn_ok = ecn_ok;
David S. Millerbb5b7c12009-12-15 20:56:42 -0800314 ireq->snd_wscale = tcp_opt.snd_wscale;
David S. Millerbb5b7c12009-12-15 20:56:42 -0800315 ireq->sack_ok = tcp_opt.sack_ok;
316 ireq->wscale_ok = tcp_opt.wscale_ok;
317 ireq->tstamp_ok = tcp_opt.saw_tstamp;
318 req->ts_recent = tcp_opt.saw_tstamp ? tcp_opt.rcv_tsval : 0;
Jerry Chu9ad7c042011-06-08 11:08:38 +0000319 treq->snt_synack = tcp_opt.saw_tstamp ? tcp_opt.rcv_tsecr : 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700320
321 /* We throwed the options of the initial SYN away, so we hope
322 * the ACK carries the same options again (see RFC1122 4.2.3.8)
323 */
324 if (opt && opt->optlen) {
Eric Dumazetf6d8bd02011-04-21 09:45:37 +0000325 int opt_size = sizeof(struct ip_options_rcu) + opt->optlen;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326
Arnaldo Carvalho de Melo2e6599c2005-06-18 22:46:52 -0700327 ireq->opt = kmalloc(opt_size, GFP_ATOMIC);
Eric Dumazetf6d8bd02011-04-21 09:45:37 +0000328 if (ireq->opt != NULL && ip_options_echo(&ireq->opt->opt, skb)) {
Arnaldo Carvalho de Melo2e6599c2005-06-18 22:46:52 -0700329 kfree(ireq->opt);
330 ireq->opt = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700331 }
332 }
333
Paul Moore284904a2009-03-27 17:10:28 -0400334 if (security_inet_conn_request(sk, skb, req)) {
335 reqsk_free(req);
336 goto out;
337 }
338
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900339 req->expires = 0UL;
340 req->retrans = 0;
341
Linus Torvalds1da177e2005-04-16 15:20:36 -0700342 /*
343 * We need to lookup the route here to get at the correct
344 * window size. We should better make sure that the window size
345 * hasn't changed since we received the original syn, but I see
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900346 * no easy way to do this.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700347 */
348 {
David S. Miller1bba6ff2011-03-31 04:54:08 -0700349 struct flowi4 fl4;
350
351 flowi4_init_output(&fl4, 0, sk->sk_mark, RT_CONN_FLAGS(sk),
352 RT_SCOPE_UNIVERSE, IPPROTO_TCP,
353 inet_sk_flowi_flags(sk),
354 (opt && opt->srr) ? opt->faddr : ireq->rmt_addr,
355 ireq->loc_addr, th->source, th->dest);
David S. Miller9d6ec932011-03-12 01:12:47 -0500356 security_req_classify_flow(req, flowi4_to_flowi(&fl4));
357 rt = ip_route_output_key(sock_net(sk), &fl4);
David S. Millerb23dd4f2011-03-02 14:31:35 -0800358 if (IS_ERR(rt)) {
Arnaldo Carvalho de Melo60236fd2005-06-18 22:47:21 -0700359 reqsk_free(req);
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900360 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700361 }
362 }
363
364 /* Try to redo what tcp_v4_send_synack did. */
Changli Gaod8d1f302010-06-10 23:31:35 -0700365 req->window_clamp = tp->window_clamp ? :dst_metric(&rt->dst, RTAX_WINDOW);
Florian Westphal4dfc2812008-04-10 03:12:40 -0700366
Linus Torvalds1da177e2005-04-16 15:20:36 -0700367 tcp_select_initial_window(tcp_full_space(sk), req->mss,
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900368 &req->rcv_wnd, &req->window_clamp,
laurent chavey31d12922009-12-15 11:15:28 +0000369 ireq->wscale_ok, &rcv_wscale,
Changli Gaod8d1f302010-06-10 23:31:35 -0700370 dst_metric(&rt->dst, RTAX_INITRWND));
Florian Westphal4dfc2812008-04-10 03:12:40 -0700371
YOSHIFUJI Hideakie905a9e2007-02-09 23:24:47 +0900372 ireq->rcv_wscale = rcv_wscale;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373
Changli Gaod8d1f302010-06-10 23:31:35 -0700374 ret = get_cookie_sock(sk, skb, req, &rt->dst);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700375out: return ret;
376}