secure_seq.c revision cf533ea53ebfae41be15b103d78e7ebec30b9969 
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
11#include <net/secure_seq.h>
12
13static u32 net_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
14
15static int __init net_secret_init(void)
16{
17	get_random_bytes(net_secret, sizeof(net_secret));
18	return 0;
19}
20late_initcall(net_secret_init);
21
22static u32 seq_scale(u32 seq)
23{
24	/*
25	 *	As close as possible to RFC 793, which
26	 *	suggests using a 250 kHz clock.
27	 *	Further reading shows this assumes 2 Mb/s networks.
28	 *	For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
29	 *	For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
30	 *	we also need to limit the resolution so that the u32 seq
31	 *	overlaps less than one time per MSL (2 minutes).
32	 *	Choosing a clock of 64 ns period is OK. (period of 274 s)
33	 */
34	return seq + (ktime_to_ns(ktime_get_real()) >> 6);
35}
36
37#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
38__u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
39				   __be16 sport, __be16 dport)
40{
41	u32 secret[MD5_MESSAGE_BYTES / 4];
42	u32 hash[MD5_DIGEST_WORDS];
43	u32 i;
44
45	memcpy(hash, saddr, 16);
46	for (i = 0; i < 4; i++)
47		secret[i] = net_secret[i] + daddr[i];
48	secret[4] = net_secret[4] +
49		(((__force u16)sport << 16) + (__force u16)dport);
50	for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
51		secret[i] = net_secret[i];
52
53	md5_transform(hash, secret);
54
55	return seq_scale(hash[0]);
56}
57EXPORT_SYMBOL(secure_tcpv6_sequence_number);
58
59u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
60			       __be16 dport)
61{
62	u32 secret[MD5_MESSAGE_BYTES / 4];
63	u32 hash[MD5_DIGEST_WORDS];
64	u32 i;
65
66	memcpy(hash, saddr, 16);
67	for (i = 0; i < 4; i++)
68		secret[i] = net_secret[i] + (__force u32) daddr[i];
69	secret[4] = net_secret[4] + (__force u32)dport;
70	for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
71		secret[i] = net_secret[i];
72
73	md5_transform(hash, secret);
74
75	return hash[0];
76}
77#endif
78
79#ifdef CONFIG_INET
80__u32 secure_ip_id(__be32 daddr)
81{
82	u32 hash[MD5_DIGEST_WORDS];
83
84	hash[0] = (__force __u32) daddr;
85	hash[1] = net_secret[13];
86	hash[2] = net_secret[14];
87	hash[3] = net_secret[15];
88
89	md5_transform(hash, net_secret);
90
91	return hash[0];
92}
93
94__u32 secure_ipv6_id(const __be32 daddr[4])
95{
96	__u32 hash[4];
97
98	memcpy(hash, daddr, 16);
99	md5_transform(hash, net_secret);
100
101	return hash[0];
102}
103
104__u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
105				 __be16 sport, __be16 dport)
106{
107	u32 hash[MD5_DIGEST_WORDS];
108
109	hash[0] = (__force u32)saddr;
110	hash[1] = (__force u32)daddr;
111	hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
112	hash[3] = net_secret[15];
113
114	md5_transform(hash, net_secret);
115
116	return seq_scale(hash[0]);
117}
118
119u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
120{
121	u32 hash[MD5_DIGEST_WORDS];
122
123	hash[0] = (__force u32)saddr;
124	hash[1] = (__force u32)daddr;
125	hash[2] = (__force u32)dport ^ net_secret[14];
126	hash[3] = net_secret[15];
127
128	md5_transform(hash, net_secret);
129
130	return hash[0];
131}
132EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
133#endif
134
135#if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE)
136u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
137				__be16 sport, __be16 dport)
138{
139	u32 hash[MD5_DIGEST_WORDS];
140	u64 seq;
141
142	hash[0] = (__force u32)saddr;
143	hash[1] = (__force u32)daddr;
144	hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
145	hash[3] = net_secret[15];
146
147	md5_transform(hash, net_secret);
148
149	seq = hash[0] | (((u64)hash[1]) << 32);
150	seq += ktime_to_ns(ktime_get_real());
151	seq &= (1ull << 48) - 1;
152
153	return seq;
154}
155EXPORT_SYMBOL(secure_dccp_sequence_number);
156
157#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
158u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
159				  __be16 sport, __be16 dport)
160{
161	u32 secret[MD5_MESSAGE_BYTES / 4];
162	u32 hash[MD5_DIGEST_WORDS];
163	u64 seq;
164	u32 i;
165
166	memcpy(hash, saddr, 16);
167	for (i = 0; i < 4; i++)
168		secret[i] = net_secret[i] + daddr[i];
169	secret[4] = net_secret[4] +
170		(((__force u16)sport << 16) + (__force u16)dport);
171	for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
172		secret[i] = net_secret[i];
173
174	md5_transform(hash, secret);
175
176	seq = hash[0] | (((u64)hash[1]) << 32);
177	seq += ktime_to_ns(ktime_get_real());
178	seq &= (1ull << 48) - 1;
179
180	return seq;
181}
182EXPORT_SYMBOL(secure_dccpv6_sequence_number);
183#endif
184#endif
185