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-rw-r--r--net/ipv4/syncookies.c58
1 files changed, 29 insertions, 29 deletions
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 6b19530905af..33016cc90f0b 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -2,16 +2,16 @@
2 * Syncookies implementation for the Linux kernel 2 * Syncookies implementation for the Linux kernel
3 * 3 *
4 * Copyright (C) 1997 Andi Kleen 4 * Copyright (C) 1997 Andi Kleen
5 * Based on ideas by D.J.Bernstein and Eric Schenk. 5 * Based on ideas by D.J.Bernstein and Eric Schenk.
6 * 6 *
7 * This program is free software; you can redistribute it and/or 7 * This program is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU General Public License 8 * modify it under the terms of the GNU General Public License
9 * as published by the Free Software Foundation; either version 9 * as published by the Free Software Foundation; either version
10 * 2 of the License, or (at your option) any later version. 10 * 2 of the License, or (at your option) any later version.
11 * 11 *
12 * $Id: syncookies.c,v 1.18 2002/02/01 22:01:04 davem Exp $ 12 * $Id: syncookies.c,v 1.18 2002/02/01 22:01:04 davem Exp $
13 * 13 *
14 * Missing: IPv6 support. 14 * Missing: IPv6 support.
15 */ 15 */
16 16
17#include <linux/tcp.h> 17#include <linux/tcp.h>
@@ -57,7 +57,7 @@ static __u32 secure_tcp_syn_cookie(__be32 saddr, __be32 daddr, __be16 sport,
57 /* 57 /*
58 * Compute the secure sequence number. 58 * Compute the secure sequence number.
59 * The output should be: 59 * The output should be:
60 * HASH(sec1,saddr,sport,daddr,dport,sec1) + sseq + (count * 2^24) 60 * HASH(sec1,saddr,sport,daddr,dport,sec1) + sseq + (count * 2^24)
61 * + (HASH(sec2,saddr,sport,daddr,dport,count,sec2) % 2^24). 61 * + (HASH(sec2,saddr,sport,daddr,dport,count,sec2) % 2^24).
62 * Where sseq is their sequence number and count increases every 62 * Where sseq is their sequence number and count increases every
63 * minute by 1. 63 * minute by 1.
@@ -99,17 +99,17 @@ static __u32 check_tcp_syn_cookie(__u32 cookie, __be32 saddr, __be32 daddr,
99 & COOKIEMASK; /* Leaving the data behind */ 99 & COOKIEMASK; /* Leaving the data behind */
100} 100}
101 101
102/* 102/*
103 * This table has to be sorted and terminated with (__u16)-1. 103 * This table has to be sorted and terminated with (__u16)-1.
104 * XXX generate a better table. 104 * XXX generate a better table.
105 * Unresolved Issues: HIPPI with a 64k MSS is not well supported. 105 * Unresolved Issues: HIPPI with a 64k MSS is not well supported.
106 */ 106 */
107static __u16 const msstab[] = { 107static __u16 const msstab[] = {
108 64 - 1, 108 64 - 1,
109 256 - 1, 109 256 - 1,
110 512 - 1, 110 512 - 1,
111 536 - 1, 111 536 - 1,
112 1024 - 1, 112 1024 - 1,
113 1440 - 1, 113 1440 - 1,
114 1460 - 1, 114 1460 - 1,
115 4312 - 1, 115 4312 - 1,
@@ -128,7 +128,7 @@ __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp)
128 int mssind; 128 int mssind;
129 const __u16 mss = *mssp; 129 const __u16 mss = *mssp;
130 130
131 131
132 tp->last_synq_overflow = jiffies; 132 tp->last_synq_overflow = jiffies;
133 133
134 /* XXX sort msstab[] by probability? Binary search? */ 134 /* XXX sort msstab[] by probability? Binary search? */
@@ -144,23 +144,23 @@ __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb, __u16 *mssp)
144 jiffies / (HZ * 60), mssind); 144 jiffies / (HZ * 60), mssind);
145} 145}
146 146
147/* 147/*
148 * This (misnamed) value is the age of syncookie which is permitted. 148 * This (misnamed) value is the age of syncookie which is permitted.
149 * Its ideal value should be dependent on TCP_TIMEOUT_INIT and 149 * Its ideal value should be dependent on TCP_TIMEOUT_INIT and
150 * sysctl_tcp_retries1. It's a rather complicated formula (exponential 150 * sysctl_tcp_retries1. It's a rather complicated formula (exponential
151 * backoff) to compute at runtime so it's currently hardcoded here. 151 * backoff) to compute at runtime so it's currently hardcoded here.
152 */ 152 */
153#define COUNTER_TRIES 4 153#define COUNTER_TRIES 4
154/* 154/*
155 * Check if a ack sequence number is a valid syncookie. 155 * Check if a ack sequence number is a valid syncookie.
156 * Return the decoded mss if it is, or 0 if not. 156 * Return the decoded mss if it is, or 0 if not.
157 */ 157 */
158static inline int cookie_check(struct sk_buff *skb, __u32 cookie) 158static inline int cookie_check(struct sk_buff *skb, __u32 cookie)
159{ 159{
160 __u32 seq; 160 __u32 seq;
161 __u32 mssind; 161 __u32 mssind;
162 162
163 seq = ntohl(skb->h.th->seq)-1; 163 seq = ntohl(skb->h.th->seq)-1;
164 mssind = check_tcp_syn_cookie(cookie, 164 mssind = check_tcp_syn_cookie(cookie,
165 skb->nh.iph->saddr, skb->nh.iph->daddr, 165 skb->nh.iph->saddr, skb->nh.iph->daddr,
166 skb->h.th->source, skb->h.th->dest, 166 skb->h.th->source, skb->h.th->dest,
@@ -191,19 +191,19 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
191 struct inet_request_sock *ireq; 191 struct inet_request_sock *ireq;
192 struct tcp_request_sock *treq; 192 struct tcp_request_sock *treq;
193 struct tcp_sock *tp = tcp_sk(sk); 193 struct tcp_sock *tp = tcp_sk(sk);
194 __u32 cookie = ntohl(skb->h.th->ack_seq) - 1; 194 __u32 cookie = ntohl(skb->h.th->ack_seq) - 1;
195 struct sock *ret = sk; 195 struct sock *ret = sk;
196 struct request_sock *req; 196 struct request_sock *req;
197 int mss; 197 int mss;
198 struct rtable *rt; 198 struct rtable *rt;
199 __u8 rcv_wscale; 199 __u8 rcv_wscale;
200 200
201 if (!sysctl_tcp_syncookies || !skb->h.th->ack) 201 if (!sysctl_tcp_syncookies || !skb->h.th->ack)
202 goto out; 202 goto out;
203 203
204 if (time_after(jiffies, tp->last_synq_overflow + TCP_TIMEOUT_INIT) || 204 if (time_after(jiffies, tp->last_synq_overflow + TCP_TIMEOUT_INIT) ||
205 (mss = cookie_check(skb, cookie)) == 0) { 205 (mss = cookie_check(skb, cookie)) == 0) {
206 NET_INC_STATS_BH(LINUX_MIB_SYNCOOKIESFAILED); 206 NET_INC_STATS_BH(LINUX_MIB_SYNCOOKIESFAILED);
207 goto out; 207 goto out;
208 } 208 }
209 209
@@ -221,9 +221,9 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
221 ireq = inet_rsk(req); 221 ireq = inet_rsk(req);
222 treq = tcp_rsk(req); 222 treq = tcp_rsk(req);
223 treq->rcv_isn = ntohl(skb->h.th->seq) - 1; 223 treq->rcv_isn = ntohl(skb->h.th->seq) - 1;
224 treq->snt_isn = cookie; 224 treq->snt_isn = cookie;
225 req->mss = mss; 225 req->mss = mss;
226 ireq->rmt_port = skb->h.th->source; 226 ireq->rmt_port = skb->h.th->source;
227 ireq->loc_addr = skb->nh.iph->daddr; 227 ireq->loc_addr = skb->nh.iph->daddr;
228 ireq->rmt_addr = skb->nh.iph->saddr; 228 ireq->rmt_addr = skb->nh.iph->saddr;
229 ireq->opt = NULL; 229 ireq->opt = NULL;
@@ -242,15 +242,15 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
242 } 242 }
243 243
244 ireq->snd_wscale = ireq->rcv_wscale = ireq->tstamp_ok = 0; 244 ireq->snd_wscale = ireq->rcv_wscale = ireq->tstamp_ok = 0;
245 ireq->wscale_ok = ireq->sack_ok = 0; 245 ireq->wscale_ok = ireq->sack_ok = 0;
246 req->expires = 0UL; 246 req->expires = 0UL;
247 req->retrans = 0; 247 req->retrans = 0;
248 248
249 /* 249 /*
250 * We need to lookup the route here to get at the correct 250 * We need to lookup the route here to get at the correct
251 * window size. We should better make sure that the window size 251 * window size. We should better make sure that the window size
252 * hasn't changed since we received the original syn, but I see 252 * hasn't changed since we received the original syn, but I see
253 * no easy way to do this. 253 * no easy way to do this.
254 */ 254 */
255 { 255 {
256 struct flowi fl = { .nl_u = { .ip4_u = 256 struct flowi fl = { .nl_u = { .ip4_u =
@@ -266,17 +266,17 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
266 security_req_classify_flow(req, &fl); 266 security_req_classify_flow(req, &fl);
267 if (ip_route_output_key(&rt, &fl)) { 267 if (ip_route_output_key(&rt, &fl)) {
268 reqsk_free(req); 268 reqsk_free(req);
269 goto out; 269 goto out;
270 } 270 }
271 } 271 }
272 272
273 /* Try to redo what tcp_v4_send_synack did. */ 273 /* Try to redo what tcp_v4_send_synack did. */
274 req->window_clamp = dst_metric(&rt->u.dst, RTAX_WINDOW); 274 req->window_clamp = dst_metric(&rt->u.dst, RTAX_WINDOW);
275 tcp_select_initial_window(tcp_full_space(sk), req->mss, 275 tcp_select_initial_window(tcp_full_space(sk), req->mss,
276 &req->rcv_wnd, &req->window_clamp, 276 &req->rcv_wnd, &req->window_clamp,
277 0, &rcv_wscale); 277 0, &rcv_wscale);
278 /* BTW win scale with syncookies is 0 by definition */ 278 /* BTW win scale with syncookies is 0 by definition */
279 ireq->rcv_wscale = rcv_wscale; 279 ireq->rcv_wscale = rcv_wscale;
280 280
281 ret = get_cookie_sock(sk, skb, req, &rt->u.dst); 281 ret = get_cookie_sock(sk, skb, req, &rt->u.dst);
282out: return ret; 282out: return ret;