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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_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}
143EXPORT_SYMBOL_GPL(secure_tcp_seq);
144
145u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
146{
147 net_secret_init();
148 return siphash_3u32((__force u32)saddr, (__force u32)daddr,
149 (__force u16)dport, &net_secret);
150}
151EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
152#endif
153
154#if IS_ENABLED(CONFIG_IP_DCCP)
155u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
156 __be16 sport, __be16 dport)
157{
158 u64 seq;
159 net_secret_init();
160 seq = siphash_3u32((__force u32)saddr, (__force u32)daddr,
161 (__force u32)sport << 16 | (__force u32)dport,
162 &net_secret);
163 seq += ktime_get_real_ns();
164 seq &= (1ull << 48) - 1;
165 return seq;
166}
167EXPORT_SYMBOL(secure_dccp_sequence_number);
168
169#if IS_ENABLED(CONFIG_IPV6)
170u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
171 __be16 sport, __be16 dport)
172{
173 const struct {
174 struct in6_addr saddr;
175 struct in6_addr daddr;
176 __be16 sport;
177 __be16 dport;
178 } __aligned(SIPHASH_ALIGNMENT) combined = {
179 .saddr = *(struct in6_addr *)saddr,
180 .daddr = *(struct in6_addr *)daddr,
181 .sport = sport,
182 .dport = dport
183 };
184 u64 seq;
185 net_secret_init();
186 seq = siphash(&combined, offsetofend(typeof(combined), dport),
187 &net_secret);
188 seq += ktime_get_real_ns();
189 seq &= (1ull << 48) - 1;
190 return seq;
191}
192EXPORT_SYMBOL(secure_dccpv6_sequence_number);
193#endif
194#endif
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