2 * Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
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>
18 #if IS_ENABLED(CONFIG_IPV6) || IS_ENABLED(CONFIG_INET)
19 #include <linux/in6.h>
22 static siphash_key_t net_secret __read_mostly;
24 static __always_inline void net_secret_init(void)
26 net_get_random_once(&net_secret, sizeof(net_secret));
31 static u32 seq_scale(u32 seq)
34 * As close as possible to RFC 793, which
35 * suggests using a 250 kHz clock.
36 * Further reading shows this assumes 2 Mb/s networks.
37 * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
38 * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
39 * we also need to limit the resolution so that the u32 seq
40 * overlaps less than one time per MSL (2 minutes).
41 * Choosing a clock of 64 ns period is OK. (period of 274 s)
43 return seq + (ktime_get_real_ns() >> 6);
47 #if IS_ENABLED(CONFIG_IPV6)
48 u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
49 __be16 sport, __be16 dport, u32 *tsoff)
52 struct in6_addr saddr;
53 struct in6_addr daddr;
56 } __aligned(SIPHASH_ALIGNMENT) combined = {
57 .saddr = *(struct in6_addr *)saddr,
58 .daddr = *(struct in6_addr *)daddr,
64 hash = siphash(&combined, offsetofend(typeof(combined), dport),
66 *tsoff = sysctl_tcp_timestamps == 1 ? (hash >> 32) : 0;
67 return seq_scale(hash);
69 EXPORT_SYMBOL(secure_tcpv6_sequence_number);
71 u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
75 struct in6_addr saddr;
76 struct in6_addr daddr;
78 } __aligned(SIPHASH_ALIGNMENT) combined = {
79 .saddr = *(struct in6_addr *)saddr,
80 .daddr = *(struct in6_addr *)daddr,
84 return siphash(&combined, offsetofend(typeof(combined), dport),
87 EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
92 /* secure_tcp_sequence_number(a, b, 0, d) == secure_ipv4_port_ephemeral(a, b, d),
93 * but fortunately, `sport' cannot be 0 in any circumstances. If this changes,
94 * it would be easy enough to have the former function use siphash_4u32, passing
95 * the arguments as separate u32.
98 u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
99 __be16 sport, __be16 dport, u32 *tsoff)
103 hash = siphash_3u32((__force u32)saddr, (__force u32)daddr,
104 (__force u32)sport << 16 | (__force u32)dport,
106 *tsoff = sysctl_tcp_timestamps == 1 ? (hash >> 32) : 0;
107 return seq_scale(hash);
110 u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
113 return siphash_3u32((__force u32)saddr, (__force u32)daddr,
114 (__force u16)dport, &net_secret);
116 EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
119 #if IS_ENABLED(CONFIG_IP_DCCP)
120 u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
121 __be16 sport, __be16 dport)
125 seq = siphash_3u32((__force u32)saddr, (__force u32)daddr,
126 (__force u32)sport << 16 | (__force u32)dport,
128 seq += ktime_get_real_ns();
129 seq &= (1ull << 48) - 1;
132 EXPORT_SYMBOL(secure_dccp_sequence_number);
134 #if IS_ENABLED(CONFIG_IPV6)
135 u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
136 __be16 sport, __be16 dport)
139 struct in6_addr saddr;
140 struct in6_addr daddr;
143 } __aligned(SIPHASH_ALIGNMENT) combined = {
144 .saddr = *(struct in6_addr *)saddr,
145 .daddr = *(struct in6_addr *)daddr,
151 seq = siphash(&combined, offsetofend(typeof(combined), dport),
153 seq += ktime_get_real_ns();
154 seq &= (1ull << 48) - 1;
157 EXPORT_SYMBOL(secure_dccpv6_sequence_number);