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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#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