Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1/*
2 * Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
3 */
4
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>
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(&ts_secret, sizeof(ts_secret));
28 net_get_random_once(&net_secret, sizeof(net_secret));
29}
30#endif
31
32#ifdef CONFIG_INET
33static u32 seq_scale(u32 seq)
34{
35 /*
36 * As close as possible to RFC 793, which
37 * suggests using a 250 kHz clock.
38 * Further reading shows this assumes 2 Mb/s networks.
39 * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
40 * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
41 * we also need to limit the resolution so that the u32 seq
42 * overlaps less than one time per MSL (2 minutes).
43 * Choosing a clock of 64 ns period is OK. (period of 274 s)
44 */
45 return seq + (ktime_get_real_ns() >> 6);
46}
47#endif
48
49#if IS_ENABLED(CONFIG_IPV6)
50static u32 secure_tcpv6_ts_off(const __be32 *saddr, const __be32 *daddr)
51{
52 const struct {
53 struct in6_addr saddr;
54 struct in6_addr daddr;
55 } __aligned(SIPHASH_ALIGNMENT) combined = {
56 .saddr = *(struct in6_addr *)saddr,
57 .daddr = *(struct in6_addr *)daddr,
58 };
59
60 if (sysctl_tcp_timestamps != 1)
61 return 0;
62
63 return siphash(&combined, offsetofend(typeof(combined), daddr),
64 &ts_secret);
65}
66
67u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
68 __be16 sport, __be16 dport, u32 *tsoff)
69{
70 const struct {
71 struct in6_addr saddr;
72 struct in6_addr daddr;
73 __be16 sport;
74 __be16 dport;
75 } __aligned(SIPHASH_ALIGNMENT) combined = {
76 .saddr = *(struct in6_addr *)saddr,
77 .daddr = *(struct in6_addr *)daddr,
78 .sport = sport,
79 .dport = dport
80 };
81 u64 hash;
82 net_secret_init();
83 hash = siphash(&combined, offsetofend(typeof(combined), dport),
84 &net_secret);
85 *tsoff = secure_tcpv6_ts_off(saddr, daddr);
86 return seq_scale(hash);
87}
88EXPORT_SYMBOL(secure_tcpv6_sequence_number);
89
90u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
91 __be16 dport)
92{
93 const struct {
94 struct in6_addr saddr;
95 struct in6_addr daddr;
96 __be16 dport;
97 } __aligned(SIPHASH_ALIGNMENT) combined = {
98 .saddr = *(struct in6_addr *)saddr,
99 .daddr = *(struct in6_addr *)daddr,
100 .dport = dport
101 };
102 net_secret_init();
103 return siphash(&combined, offsetofend(typeof(combined), dport),
104 &net_secret);
105}
106EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
107#endif
108
109#ifdef CONFIG_INET
110static u32 secure_tcp_ts_off(__be32 saddr, __be32 daddr)
111{
112 if (sysctl_tcp_timestamps != 1)
113 return 0;
114
115 return siphash_2u32((__force u32)saddr, (__force u32)daddr,
116 &ts_secret);
117}
118
119/* secure_tcp_sequence_number(a, b, 0, d) == secure_ipv4_port_ephemeral(a, b, d),
120 * but fortunately, `sport' cannot be 0 in any circumstances. If this changes,
121 * it would be easy enough to have the former function use siphash_4u32, passing
122 * the arguments as separate u32.
123 */
124
125u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
126 __be16 sport, __be16 dport, u32 *tsoff)
127{
128 u64 hash;
129 net_secret_init();
130 hash = siphash_3u32((__force u32)saddr, (__force u32)daddr,
131 (__force u32)sport << 16 | (__force u32)dport,
132 &net_secret);
133 *tsoff = secure_tcp_ts_off(saddr, daddr);
134 return seq_scale(hash);
135}
136
137u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
138{
139 net_secret_init();
140 return siphash_3u32((__force u32)saddr, (__force u32)daddr,
141 (__force u16)dport, &net_secret);
142}
143EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
144#endif
145
146#if IS_ENABLED(CONFIG_IP_DCCP)
147u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
148 __be16 sport, __be16 dport)
149{
150 u64 seq;
151 net_secret_init();
152 seq = siphash_3u32((__force u32)saddr, (__force u32)daddr,
153 (__force u32)sport << 16 | (__force u32)dport,
154 &net_secret);
155 seq += ktime_get_real_ns();
156 seq &= (1ull << 48) - 1;
157 return seq;
158}
159EXPORT_SYMBOL(secure_dccp_sequence_number);
160
161#if IS_ENABLED(CONFIG_IPV6)
162u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
163 __be16 sport, __be16 dport)
164{
165 const struct {
166 struct in6_addr saddr;
167 struct in6_addr daddr;
168 __be16 sport;
169 __be16 dport;
170 } __aligned(SIPHASH_ALIGNMENT) combined = {
171 .saddr = *(struct in6_addr *)saddr,
172 .daddr = *(struct in6_addr *)daddr,
173 .sport = sport,
174 .dport = dport
175 };
176 u64 seq;
177 net_secret_init();
178 seq = siphash(&combined, offsetofend(typeof(combined), dport),
179 &net_secret);
180 seq += ktime_get_real_ns();
181 seq &= (1ull << 48) - 1;
182 return seq;
183}
184EXPORT_SYMBOL(secure_dccpv6_sequence_number);
185#endif
186#endif