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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
4 */
5
6#include <linux/kernel.h>
7#include <linux/init.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_aligned_key_t net_secret;
23static siphash_aligned_key_t ts_secret;
24
25#define EPHEMERAL_PORT_SHUFFLE_PERIOD (10 * HZ)
26
27static __always_inline void net_secret_init(void)
28{
29 net_get_random_once(&net_secret, sizeof(net_secret));
30}
31
32static __always_inline void ts_secret_init(void)
33{
34 net_get_random_once(&ts_secret, sizeof(ts_secret));
35}
36#endif
37
38#ifdef CONFIG_INET
39static u32 seq_scale(u32 seq)
40{
41 /*
42 * As close as possible to RFC 793, which
43 * suggests using a 250 kHz clock.
44 * Further reading shows this assumes 2 Mb/s networks.
45 * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
46 * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
47 * we also need to limit the resolution so that the u32 seq
48 * overlaps less than one time per MSL (2 minutes).
49 * Choosing a clock of 64 ns period is OK. (period of 274 s)
50 */
51 return seq + (ktime_get_real_ns() >> 6);
52}
53#endif
54
55#if IS_ENABLED(CONFIG_IPV6)
56u32 secure_tcpv6_ts_off(const struct net *net,
57 const __be32 *saddr, const __be32 *daddr)
58{
59 const struct {
60 struct in6_addr saddr;
61 struct in6_addr daddr;
62 } __aligned(SIPHASH_ALIGNMENT) combined = {
63 .saddr = *(struct in6_addr *)saddr,
64 .daddr = *(struct in6_addr *)daddr,
65 };
66
67 if (READ_ONCE(net->ipv4.sysctl_tcp_timestamps) != 1)
68 return 0;
69
70 ts_secret_init();
71 return siphash(&combined, offsetofend(typeof(combined), daddr),
72 &ts_secret);
73}
74EXPORT_SYMBOL(secure_tcpv6_ts_off);
75
76u32 secure_tcpv6_seq(const __be32 *saddr, const __be32 *daddr,
77 __be16 sport, __be16 dport)
78{
79 const struct {
80 struct in6_addr saddr;
81 struct in6_addr daddr;
82 __be16 sport;
83 __be16 dport;
84 } __aligned(SIPHASH_ALIGNMENT) combined = {
85 .saddr = *(struct in6_addr *)saddr,
86 .daddr = *(struct in6_addr *)daddr,
87 .sport = sport,
88 .dport = dport
89 };
90 u32 hash;
91
92 net_secret_init();
93 hash = siphash(&combined, offsetofend(typeof(combined), dport),
94 &net_secret);
95 return seq_scale(hash);
96}
97EXPORT_SYMBOL(secure_tcpv6_seq);
98
99u64 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
100 __be16 dport)
101{
102 const struct {
103 struct in6_addr saddr;
104 struct in6_addr daddr;
105 unsigned int timeseed;
106 __be16 dport;
107 } __aligned(SIPHASH_ALIGNMENT) combined = {
108 .saddr = *(struct in6_addr *)saddr,
109 .daddr = *(struct in6_addr *)daddr,
110 .timeseed = jiffies / EPHEMERAL_PORT_SHUFFLE_PERIOD,
111 .dport = dport,
112 };
113 net_secret_init();
114 return siphash(&combined, offsetofend(typeof(combined), dport),
115 &net_secret);
116}
117EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
118#endif
119
120#ifdef CONFIG_INET
121u32 secure_tcp_ts_off(const struct net *net, __be32 saddr, __be32 daddr)
122{
123 if (READ_ONCE(net->ipv4.sysctl_tcp_timestamps) != 1)
124 return 0;
125
126 ts_secret_init();
127 return siphash_2u32((__force u32)saddr, (__force u32)daddr,
128 &ts_secret);
129}
130
131/* secure_tcp_seq_and_tsoff(a, b, 0, d) == secure_ipv4_port_ephemeral(a, b, d),
132 * but fortunately, `sport' cannot be 0 in any circumstances. If this changes,
133 * it would be easy enough to have the former function use siphash_4u32, passing
134 * the arguments as separate u32.
135 */
136u32 secure_tcp_seq(__be32 saddr, __be32 daddr,
137 __be16 sport, __be16 dport)
138{
139 u32 hash;
140
141 net_secret_init();
142 hash = siphash_3u32((__force u32)saddr, (__force u32)daddr,
143 (__force u32)sport << 16 | (__force u32)dport,
144 &net_secret);
145 return seq_scale(hash);
146}
147EXPORT_SYMBOL_GPL(secure_tcp_seq);
148
149u64 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
150{
151 net_secret_init();
152 return siphash_4u32((__force u32)saddr, (__force u32)daddr,
153 (__force u16)dport,
154 jiffies / EPHEMERAL_PORT_SHUFFLE_PERIOD,
155 &net_secret);
156}
157EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
158#endif
159
160#if IS_ENABLED(CONFIG_IP_DCCP)
161u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
162 __be16 sport, __be16 dport)
163{
164 u64 seq;
165 net_secret_init();
166 seq = siphash_3u32((__force u32)saddr, (__force u32)daddr,
167 (__force u32)sport << 16 | (__force u32)dport,
168 &net_secret);
169 seq += ktime_get_real_ns();
170 seq &= (1ull << 48) - 1;
171 return seq;
172}
173EXPORT_SYMBOL(secure_dccp_sequence_number);
174
175#if IS_ENABLED(CONFIG_IPV6)
176u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
177 __be16 sport, __be16 dport)
178{
179 const struct {
180 struct in6_addr saddr;
181 struct in6_addr daddr;
182 __be16 sport;
183 __be16 dport;
184 } __aligned(SIPHASH_ALIGNMENT) combined = {
185 .saddr = *(struct in6_addr *)saddr,
186 .daddr = *(struct in6_addr *)daddr,
187 .sport = sport,
188 .dport = dport
189 };
190 u64 seq;
191 net_secret_init();
192 seq = siphash(&combined, offsetofend(typeof(combined), dport),
193 &net_secret);
194 seq += ktime_get_real_ns();
195 seq &= (1ull << 48) - 1;
196 return seq;
197}
198EXPORT_SYMBOL(secure_dccpv6_sequence_number);
199#endif
200#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#include <linux/net.h>
11
12#include <net/secure_seq.h>
13
14#if IS_ENABLED(CONFIG_IPV6) || IS_ENABLED(CONFIG_INET)
15#include <net/tcp.h>
16#define NET_SECRET_SIZE (MD5_MESSAGE_BYTES / 4)
17
18static u32 net_secret[NET_SECRET_SIZE] ____cacheline_aligned;
19
20static __always_inline void net_secret_init(void)
21{
22 net_get_random_once(net_secret, sizeof(net_secret));
23}
24#endif
25
26#ifdef CONFIG_INET
27static u32 seq_scale(u32 seq)
28{
29 /*
30 * As close as possible to RFC 793, which
31 * suggests using a 250 kHz clock.
32 * Further reading shows this assumes 2 Mb/s networks.
33 * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
34 * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
35 * we also need to limit the resolution so that the u32 seq
36 * overlaps less than one time per MSL (2 minutes).
37 * Choosing a clock of 64 ns period is OK. (period of 274 s)
38 */
39 return seq + (ktime_get_real_ns() >> 6);
40}
41#endif
42
43#if IS_ENABLED(CONFIG_IPV6)
44u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
45 __be16 sport, __be16 dport, u32 *tsoff)
46{
47 u32 secret[MD5_MESSAGE_BYTES / 4];
48 u32 hash[MD5_DIGEST_WORDS];
49 u32 i;
50
51 net_secret_init();
52 memcpy(hash, saddr, 16);
53 for (i = 0; i < 4; i++)
54 secret[i] = net_secret[i] + (__force u32)daddr[i];
55 secret[4] = net_secret[4] +
56 (((__force u16)sport << 16) + (__force u16)dport);
57 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
58 secret[i] = net_secret[i];
59
60 md5_transform(hash, secret);
61
62 *tsoff = sysctl_tcp_timestamps == 1 ? hash[1] : 0;
63 return seq_scale(hash[0]);
64}
65EXPORT_SYMBOL(secure_tcpv6_sequence_number);
66
67u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
68 __be16 dport)
69{
70 u32 secret[MD5_MESSAGE_BYTES / 4];
71 u32 hash[MD5_DIGEST_WORDS];
72 u32 i;
73
74 net_secret_init();
75 memcpy(hash, saddr, 16);
76 for (i = 0; i < 4; i++)
77 secret[i] = net_secret[i] + (__force u32) daddr[i];
78 secret[4] = net_secret[4] + (__force u32)dport;
79 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
80 secret[i] = net_secret[i];
81
82 md5_transform(hash, secret);
83
84 return hash[0];
85}
86EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
87#endif
88
89#ifdef CONFIG_INET
90
91u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
92 __be16 sport, __be16 dport, u32 *tsoff)
93{
94 u32 hash[MD5_DIGEST_WORDS];
95
96 net_secret_init();
97 hash[0] = (__force u32)saddr;
98 hash[1] = (__force u32)daddr;
99 hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
100 hash[3] = net_secret[15];
101
102 md5_transform(hash, net_secret);
103
104 *tsoff = sysctl_tcp_timestamps == 1 ? hash[1] : 0;
105 return seq_scale(hash[0]);
106}
107
108u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
109{
110 u32 hash[MD5_DIGEST_WORDS];
111
112 net_secret_init();
113 hash[0] = (__force u32)saddr;
114 hash[1] = (__force u32)daddr;
115 hash[2] = (__force u32)dport ^ net_secret[14];
116 hash[3] = net_secret[15];
117
118 md5_transform(hash, net_secret);
119
120 return hash[0];
121}
122EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
123#endif
124
125#if IS_ENABLED(CONFIG_IP_DCCP)
126u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
127 __be16 sport, __be16 dport)
128{
129 u32 hash[MD5_DIGEST_WORDS];
130 u64 seq;
131
132 net_secret_init();
133 hash[0] = (__force u32)saddr;
134 hash[1] = (__force u32)daddr;
135 hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
136 hash[3] = net_secret[15];
137
138 md5_transform(hash, net_secret);
139
140 seq = hash[0] | (((u64)hash[1]) << 32);
141 seq += ktime_get_real_ns();
142 seq &= (1ull << 48) - 1;
143
144 return seq;
145}
146EXPORT_SYMBOL(secure_dccp_sequence_number);
147
148#if IS_ENABLED(CONFIG_IPV6)
149u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
150 __be16 sport, __be16 dport)
151{
152 u32 secret[MD5_MESSAGE_BYTES / 4];
153 u32 hash[MD5_DIGEST_WORDS];
154 u64 seq;
155 u32 i;
156
157 net_secret_init();
158 memcpy(hash, saddr, 16);
159 for (i = 0; i < 4; i++)
160 secret[i] = net_secret[i] + (__force u32)daddr[i];
161 secret[4] = net_secret[4] +
162 (((__force u16)sport << 16) + (__force u16)dport);
163 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
164 secret[i] = net_secret[i];
165
166 md5_transform(hash, secret);
167
168 seq = hash[0] | (((u64)hash[1]) << 32);
169 seq += ktime_get_real_ns();
170 seq &= (1ull << 48) - 1;
171
172 return seq;
173}
174EXPORT_SYMBOL(secure_dccpv6_sequence_number);
175#endif
176#endif