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1/*
2 * Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
3 */
4
5#include <linux/kernel.h>
6#include <linux/init.h>
7#include <linux/cryptohash.h>
8#include <linux/module.h>
9#include <linux/cache.h>
10#include <linux/random.h>
11#include <linux/hrtimer.h>
12#include <linux/ktime.h>
13#include <linux/string.h>
14#include <linux/net.h>
15#include <linux/siphash.h>
16#include <net/secure_seq.h>
17
18#if IS_ENABLED(CONFIG_IPV6) || IS_ENABLED(CONFIG_INET)
19#include <linux/in6.h>
20#include <net/tcp.h>
21
22static siphash_key_t net_secret __read_mostly;
23static siphash_key_t ts_secret __read_mostly;
24
25static __always_inline void net_secret_init(void)
26{
27 net_get_random_once(&net_secret, sizeof(net_secret));
28}
29
30static __always_inline void ts_secret_init(void)
31{
32 net_get_random_once(&ts_secret, sizeof(ts_secret));
33}
34#endif
35
36#ifdef CONFIG_INET
37static u32 seq_scale(u32 seq)
38{
39 /*
40 * As close as possible to RFC 793, which
41 * suggests using a 250 kHz clock.
42 * Further reading shows this assumes 2 Mb/s networks.
43 * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
44 * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
45 * we also need to limit the resolution so that the u32 seq
46 * overlaps less than one time per MSL (2 minutes).
47 * Choosing a clock of 64 ns period is OK. (period of 274 s)
48 */
49 return seq + (ktime_get_real_ns() >> 6);
50}
51#endif
52
53#if IS_ENABLED(CONFIG_IPV6)
54u32 secure_tcpv6_ts_off(const struct net *net,
55 const __be32 *saddr, const __be32 *daddr)
56{
57 const struct {
58 struct in6_addr saddr;
59 struct in6_addr daddr;
60 } __aligned(SIPHASH_ALIGNMENT) combined = {
61 .saddr = *(struct in6_addr *)saddr,
62 .daddr = *(struct in6_addr *)daddr,
63 };
64
65 if (net->ipv4.sysctl_tcp_timestamps != 1)
66 return 0;
67
68 ts_secret_init();
69 return siphash(&combined, offsetofend(typeof(combined), daddr),
70 &ts_secret);
71}
72EXPORT_SYMBOL(secure_tcpv6_ts_off);
73
74u32 secure_tcpv6_seq(const __be32 *saddr, const __be32 *daddr,
75 __be16 sport, __be16 dport)
76{
77 const struct {
78 struct in6_addr saddr;
79 struct in6_addr daddr;
80 __be16 sport;
81 __be16 dport;
82 } __aligned(SIPHASH_ALIGNMENT) combined = {
83 .saddr = *(struct in6_addr *)saddr,
84 .daddr = *(struct in6_addr *)daddr,
85 .sport = sport,
86 .dport = dport
87 };
88 u32 hash;
89
90 net_secret_init();
91 hash = siphash(&combined, offsetofend(typeof(combined), dport),
92 &net_secret);
93 return seq_scale(hash);
94}
95EXPORT_SYMBOL(secure_tcpv6_seq);
96
97u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
98 __be16 dport)
99{
100 const struct {
101 struct in6_addr saddr;
102 struct in6_addr daddr;
103 __be16 dport;
104 } __aligned(SIPHASH_ALIGNMENT) combined = {
105 .saddr = *(struct in6_addr *)saddr,
106 .daddr = *(struct in6_addr *)daddr,
107 .dport = dport
108 };
109 net_secret_init();
110 return siphash(&combined, offsetofend(typeof(combined), dport),
111 &net_secret);
112}
113EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
114#endif
115
116#ifdef CONFIG_INET
117u32 secure_tcp_ts_off(const struct net *net, __be32 saddr, __be32 daddr)
118{
119 if (net->ipv4.sysctl_tcp_timestamps != 1)
120 return 0;
121
122 ts_secret_init();
123 return siphash_2u32((__force u32)saddr, (__force u32)daddr,
124 &ts_secret);
125}
126
127/* secure_tcp_seq_and_tsoff(a, b, 0, d) == secure_ipv4_port_ephemeral(a, b, d),
128 * but fortunately, `sport' cannot be 0 in any circumstances. If this changes,
129 * it would be easy enough to have the former function use siphash_4u32, passing
130 * the arguments as separate u32.
131 */
132u32 secure_tcp_seq(__be32 saddr, __be32 daddr,
133 __be16 sport, __be16 dport)
134{
135 u32 hash;
136
137 net_secret_init();
138 hash = siphash_3u32((__force u32)saddr, (__force u32)daddr,
139 (__force u32)sport << 16 | (__force u32)dport,
140 &net_secret);
141 return seq_scale(hash);
142}
143
144u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
145{
146 net_secret_init();
147 return siphash_3u32((__force u32)saddr, (__force u32)daddr,
148 (__force u16)dport, &net_secret);
149}
150EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
151#endif
152
153#if IS_ENABLED(CONFIG_IP_DCCP)
154u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
155 __be16 sport, __be16 dport)
156{
157 u64 seq;
158 net_secret_init();
159 seq = siphash_3u32((__force u32)saddr, (__force u32)daddr,
160 (__force u32)sport << 16 | (__force u32)dport,
161 &net_secret);
162 seq += ktime_get_real_ns();
163 seq &= (1ull << 48) - 1;
164 return seq;
165}
166EXPORT_SYMBOL(secure_dccp_sequence_number);
167
168#if IS_ENABLED(CONFIG_IPV6)
169u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
170 __be16 sport, __be16 dport)
171{
172 const struct {
173 struct in6_addr saddr;
174 struct in6_addr daddr;
175 __be16 sport;
176 __be16 dport;
177 } __aligned(SIPHASH_ALIGNMENT) combined = {
178 .saddr = *(struct in6_addr *)saddr,
179 .daddr = *(struct in6_addr *)daddr,
180 .sport = sport,
181 .dport = dport
182 };
183 u64 seq;
184 net_secret_init();
185 seq = siphash(&combined, offsetofend(typeof(combined), dport),
186 &net_secret);
187 seq += ktime_get_real_ns();
188 seq &= (1ull << 48) - 1;
189 return seq;
190}
191EXPORT_SYMBOL(secure_dccpv6_sequence_number);
192#endif
193#endif
1#include <linux/kernel.h>
2#include <linux/init.h>
3#include <linux/cryptohash.h>
4#include <linux/module.h>
5#include <linux/cache.h>
6#include <linux/random.h>
7#include <linux/hrtimer.h>
8#include <linux/ktime.h>
9#include <linux/string.h>
10
11#include <net/secure_seq.h>
12
13static u32 net_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
14
15static int __init net_secret_init(void)
16{
17 get_random_bytes(net_secret, sizeof(net_secret));
18 return 0;
19}
20late_initcall(net_secret_init);
21
22static u32 seq_scale(u32 seq)
23{
24 /*
25 * As close as possible to RFC 793, which
26 * suggests using a 250 kHz clock.
27 * Further reading shows this assumes 2 Mb/s networks.
28 * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
29 * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
30 * we also need to limit the resolution so that the u32 seq
31 * overlaps less than one time per MSL (2 minutes).
32 * Choosing a clock of 64 ns period is OK. (period of 274 s)
33 */
34 return seq + (ktime_to_ns(ktime_get_real()) >> 6);
35}
36
37#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
38__u32 secure_tcpv6_sequence_number(__be32 *saddr, __be32 *daddr,
39 __be16 sport, __be16 dport)
40{
41 u32 secret[MD5_MESSAGE_BYTES / 4];
42 u32 hash[MD5_DIGEST_WORDS];
43 u32 i;
44
45 memcpy(hash, saddr, 16);
46 for (i = 0; i < 4; i++)
47 secret[i] = net_secret[i] + daddr[i];
48 secret[4] = net_secret[4] +
49 (((__force u16)sport << 16) + (__force u16)dport);
50 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
51 secret[i] = net_secret[i];
52
53 md5_transform(hash, secret);
54
55 return seq_scale(hash[0]);
56}
57EXPORT_SYMBOL(secure_tcpv6_sequence_number);
58
59u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
60 __be16 dport)
61{
62 u32 secret[MD5_MESSAGE_BYTES / 4];
63 u32 hash[MD5_DIGEST_WORDS];
64 u32 i;
65
66 memcpy(hash, saddr, 16);
67 for (i = 0; i < 4; i++)
68 secret[i] = net_secret[i] + (__force u32) daddr[i];
69 secret[4] = net_secret[4] + (__force u32)dport;
70 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
71 secret[i] = net_secret[i];
72
73 md5_transform(hash, secret);
74
75 return hash[0];
76}
77#endif
78
79#ifdef CONFIG_INET
80__u32 secure_ip_id(__be32 daddr)
81{
82 u32 hash[MD5_DIGEST_WORDS];
83
84 hash[0] = (__force __u32) daddr;
85 hash[1] = net_secret[13];
86 hash[2] = net_secret[14];
87 hash[3] = net_secret[15];
88
89 md5_transform(hash, net_secret);
90
91 return hash[0];
92}
93
94__u32 secure_ipv6_id(const __be32 daddr[4])
95{
96 __u32 hash[4];
97
98 memcpy(hash, daddr, 16);
99 md5_transform(hash, net_secret);
100
101 return hash[0];
102}
103
104__u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
105 __be16 sport, __be16 dport)
106{
107 u32 hash[MD5_DIGEST_WORDS];
108
109 hash[0] = (__force u32)saddr;
110 hash[1] = (__force u32)daddr;
111 hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
112 hash[3] = net_secret[15];
113
114 md5_transform(hash, net_secret);
115
116 return seq_scale(hash[0]);
117}
118
119u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
120{
121 u32 hash[MD5_DIGEST_WORDS];
122
123 hash[0] = (__force u32)saddr;
124 hash[1] = (__force u32)daddr;
125 hash[2] = (__force u32)dport ^ net_secret[14];
126 hash[3] = net_secret[15];
127
128 md5_transform(hash, net_secret);
129
130 return hash[0];
131}
132EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
133#endif
134
135#if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE)
136u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
137 __be16 sport, __be16 dport)
138{
139 u32 hash[MD5_DIGEST_WORDS];
140 u64 seq;
141
142 hash[0] = (__force u32)saddr;
143 hash[1] = (__force u32)daddr;
144 hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
145 hash[3] = net_secret[15];
146
147 md5_transform(hash, net_secret);
148
149 seq = hash[0] | (((u64)hash[1]) << 32);
150 seq += ktime_to_ns(ktime_get_real());
151 seq &= (1ull << 48) - 1;
152
153 return seq;
154}
155EXPORT_SYMBOL(secure_dccp_sequence_number);
156
157#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
158u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
159 __be16 sport, __be16 dport)
160{
161 u32 secret[MD5_MESSAGE_BYTES / 4];
162 u32 hash[MD5_DIGEST_WORDS];
163 u64 seq;
164 u32 i;
165
166 memcpy(hash, saddr, 16);
167 for (i = 0; i < 4; i++)
168 secret[i] = net_secret[i] + daddr[i];
169 secret[4] = net_secret[4] +
170 (((__force u16)sport << 16) + (__force u16)dport);
171 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
172 secret[i] = net_secret[i];
173
174 md5_transform(hash, secret);
175
176 seq = hash[0] | (((u64)hash[1]) << 32);
177 seq += ktime_to_ns(ktime_get_real());
178 seq &= (1ull << 48) - 1;
179
180 return seq;
181}
182EXPORT_SYMBOL(secure_dccpv6_sequence_number);
183#endif
184#endif