Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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#include <net/tcp.h>
16#define NET_SECRET_SIZE (MD5_MESSAGE_BYTES / 4)
17
18static u32 net_secret[NET_SECRET_SIZE] ____cacheline_aligned;
19
20static __always_inline void net_secret_init(void)
21{
22 net_get_random_once(net_secret, sizeof(net_secret));
23}
24#endif
25
26#ifdef CONFIG_INET
27static u32 seq_scale(u32 seq)
28{
29 /*
30 * As close as possible to RFC 793, which
31 * suggests using a 250 kHz clock.
32 * Further reading shows this assumes 2 Mb/s networks.
33 * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
34 * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
35 * we also need to limit the resolution so that the u32 seq
36 * overlaps less than one time per MSL (2 minutes).
37 * Choosing a clock of 64 ns period is OK. (period of 274 s)
38 */
39 return seq + (ktime_get_real_ns() >> 6);
40}
41#endif
42
43#if IS_ENABLED(CONFIG_IPV6)
44u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
45 __be16 sport, __be16 dport, u32 *tsoff)
46{
47 u32 secret[MD5_MESSAGE_BYTES / 4];
48 u32 hash[MD5_DIGEST_WORDS];
49 u32 i;
50
51 net_secret_init();
52 memcpy(hash, saddr, 16);
53 for (i = 0; i < 4; i++)
54 secret[i] = net_secret[i] + (__force u32)daddr[i];
55 secret[4] = net_secret[4] +
56 (((__force u16)sport << 16) + (__force u16)dport);
57 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
58 secret[i] = net_secret[i];
59
60 md5_transform(hash, secret);
61
62 *tsoff = sysctl_tcp_timestamps == 1 ? hash[1] : 0;
63 return seq_scale(hash[0]);
64}
65EXPORT_SYMBOL(secure_tcpv6_sequence_number);
66
67u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
68 __be16 dport)
69{
70 u32 secret[MD5_MESSAGE_BYTES / 4];
71 u32 hash[MD5_DIGEST_WORDS];
72 u32 i;
73
74 net_secret_init();
75 memcpy(hash, saddr, 16);
76 for (i = 0; i < 4; i++)
77 secret[i] = net_secret[i] + (__force u32) daddr[i];
78 secret[4] = net_secret[4] + (__force u32)dport;
79 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
80 secret[i] = net_secret[i];
81
82 md5_transform(hash, secret);
83
84 return hash[0];
85}
86EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
87#endif
88
89#ifdef CONFIG_INET
90
91u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
92 __be16 sport, __be16 dport, u32 *tsoff)
93{
94 u32 hash[MD5_DIGEST_WORDS];
95
96 net_secret_init();
97 hash[0] = (__force u32)saddr;
98 hash[1] = (__force u32)daddr;
99 hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
100 hash[3] = net_secret[15];
101
102 md5_transform(hash, net_secret);
103
104 *tsoff = sysctl_tcp_timestamps == 1 ? hash[1] : 0;
105 return seq_scale(hash[0]);
106}
107
108u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
109{
110 u32 hash[MD5_DIGEST_WORDS];
111
112 net_secret_init();
113 hash[0] = (__force u32)saddr;
114 hash[1] = (__force u32)daddr;
115 hash[2] = (__force u32)dport ^ net_secret[14];
116 hash[3] = net_secret[15];
117
118 md5_transform(hash, net_secret);
119
120 return hash[0];
121}
122EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
123#endif
124
125#if IS_ENABLED(CONFIG_IP_DCCP)
126u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
127 __be16 sport, __be16 dport)
128{
129 u32 hash[MD5_DIGEST_WORDS];
130 u64 seq;
131
132 net_secret_init();
133 hash[0] = (__force u32)saddr;
134 hash[1] = (__force u32)daddr;
135 hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
136 hash[3] = net_secret[15];
137
138 md5_transform(hash, net_secret);
139
140 seq = hash[0] | (((u64)hash[1]) << 32);
141 seq += ktime_get_real_ns();
142 seq &= (1ull << 48) - 1;
143
144 return seq;
145}
146EXPORT_SYMBOL(secure_dccp_sequence_number);
147
148#if IS_ENABLED(CONFIG_IPV6)
149u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
150 __be16 sport, __be16 dport)
151{
152 u32 secret[MD5_MESSAGE_BYTES / 4];
153 u32 hash[MD5_DIGEST_WORDS];
154 u64 seq;
155 u32 i;
156
157 net_secret_init();
158 memcpy(hash, saddr, 16);
159 for (i = 0; i < 4; i++)
160 secret[i] = net_secret[i] + (__force u32)daddr[i];
161 secret[4] = net_secret[4] +
162 (((__force u16)sport << 16) + (__force u16)dport);
163 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
164 secret[i] = net_secret[i];
165
166 md5_transform(hash, secret);
167
168 seq = hash[0] | (((u64)hash[1]) << 32);
169 seq += ktime_get_real_ns();
170 seq &= (1ull << 48) - 1;
171
172 return seq;
173}
174EXPORT_SYMBOL(secure_dccpv6_sequence_number);
175#endif
176#endif