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(&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 __be32 *saddr, const __be32 *daddr)
55{
56 const struct {
57 struct in6_addr saddr;
58 struct in6_addr daddr;
59 } __aligned(SIPHASH_ALIGNMENT) combined = {
60 .saddr = *(struct in6_addr *)saddr,
61 .daddr = *(struct in6_addr *)daddr,
62 };
63
64 if (sysctl_tcp_timestamps != 1)
65 return 0;
66
67 ts_secret_init();
68 return siphash(&combined, offsetofend(typeof(combined), daddr),
69 &ts_secret);
70}
71EXPORT_SYMBOL(secure_tcpv6_ts_off);
72
73u32 secure_tcpv6_seq(const __be32 *saddr, const __be32 *daddr,
74 __be16 sport, __be16 dport)
75{
76 const struct {
77 struct in6_addr saddr;
78 struct in6_addr daddr;
79 __be16 sport;
80 __be16 dport;
81 } __aligned(SIPHASH_ALIGNMENT) combined = {
82 .saddr = *(struct in6_addr *)saddr,
83 .daddr = *(struct in6_addr *)daddr,
84 .sport = sport,
85 .dport = dport
86 };
87 u32 hash;
88
89 net_secret_init();
90 hash = siphash(&combined, offsetofend(typeof(combined), dport),
91 &net_secret);
92 return seq_scale(hash);
93}
94EXPORT_SYMBOL(secure_tcpv6_seq);
95
96u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
97 __be16 dport)
98{
99 const struct {
100 struct in6_addr saddr;
101 struct in6_addr daddr;
102 __be16 dport;
103 } __aligned(SIPHASH_ALIGNMENT) combined = {
104 .saddr = *(struct in6_addr *)saddr,
105 .daddr = *(struct in6_addr *)daddr,
106 .dport = dport
107 };
108 net_secret_init();
109 return siphash(&combined, offsetofend(typeof(combined), dport),
110 &net_secret);
111}
112EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
113#endif
114
115#ifdef CONFIG_INET
116u32 secure_tcp_ts_off(__be32 saddr, __be32 daddr)
117{
118 if (sysctl_tcp_timestamps != 1)
119 return 0;
120
121 ts_secret_init();
122 return siphash_2u32((__force u32)saddr, (__force u32)daddr,
123 &ts_secret);
124}
125
126/* secure_tcp_seq_and_tsoff(a, b, 0, d) == secure_ipv4_port_ephemeral(a, b, d),
127 * but fortunately, `sport' cannot be 0 in any circumstances. If this changes,
128 * it would be easy enough to have the former function use siphash_4u32, passing
129 * the arguments as separate u32.
130 */
131u32 secure_tcp_seq(__be32 saddr, __be32 daddr,
132 __be16 sport, __be16 dport)
133{
134 u32 hash;
135
136 net_secret_init();
137 hash = siphash_3u32((__force u32)saddr, (__force u32)daddr,
138 (__force u32)sport << 16 | (__force u32)dport,
139 &net_secret);
140 return seq_scale(hash);
141}
142
143u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
144{
145 net_secret_init();
146 return siphash_3u32((__force u32)saddr, (__force u32)daddr,
147 (__force u16)dport, &net_secret);
148}
149EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
150#endif
151
152#if IS_ENABLED(CONFIG_IP_DCCP)
153u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
154 __be16 sport, __be16 dport)
155{
156 u64 seq;
157 net_secret_init();
158 seq = siphash_3u32((__force u32)saddr, (__force u32)daddr,
159 (__force u32)sport << 16 | (__force u32)dport,
160 &net_secret);
161 seq += ktime_get_real_ns();
162 seq &= (1ull << 48) - 1;
163 return seq;
164}
165EXPORT_SYMBOL(secure_dccp_sequence_number);
166
167#if IS_ENABLED(CONFIG_IPV6)
168u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
169 __be16 sport, __be16 dport)
170{
171 const struct {
172 struct in6_addr saddr;
173 struct in6_addr daddr;
174 __be16 sport;
175 __be16 dport;
176 } __aligned(SIPHASH_ALIGNMENT) combined = {
177 .saddr = *(struct in6_addr *)saddr,
178 .daddr = *(struct in6_addr *)daddr,
179 .sport = sport,
180 .dport = dport
181 };
182 u64 seq;
183 net_secret_init();
184 seq = siphash(&combined, offsetofend(typeof(combined), dport),
185 &net_secret);
186 seq += ktime_get_real_ns();
187 seq &= (1ull << 48) - 1;
188 return seq;
189}
190EXPORT_SYMBOL(secure_dccpv6_sequence_number);
191#endif
192#endif