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