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
13 static u32 net_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
14
net_secret_init(void)15 static int __init net_secret_init(void)
16 {
17 get_random_bytes(net_secret, sizeof(net_secret));
18 return 0;
19 }
20 late_initcall(net_secret_init);
21
22 #ifdef CONFIG_INET
seq_scale(u32 seq)23 static u32 seq_scale(u32 seq)
24 {
25 /*
26 * As close as possible to RFC 793, which
27 * suggests using a 250 kHz clock.
28 * Further reading shows this assumes 2 Mb/s networks.
29 * For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
30 * For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
31 * we also need to limit the resolution so that the u32 seq
32 * overlaps less than one time per MSL (2 minutes).
33 * Choosing a clock of 64 ns period is OK. (period of 274 s)
34 */
35 return seq + (ktime_to_ns(ktime_get_real()) >> 6);
36 }
37 #endif
38
39 #if IS_ENABLED(CONFIG_IPV6)
secure_tcpv6_sequence_number(const __be32 * saddr,const __be32 * daddr,__be16 sport,__be16 dport)40 __u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
41 __be16 sport, __be16 dport)
42 {
43 u32 secret[MD5_MESSAGE_BYTES / 4];
44 u32 hash[MD5_DIGEST_WORDS];
45 u32 i;
46
47 memcpy(hash, saddr, 16);
48 for (i = 0; i < 4; i++)
49 secret[i] = net_secret[i] + (__force u32)daddr[i];
50 secret[4] = net_secret[4] +
51 (((__force u16)sport << 16) + (__force u16)dport);
52 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
53 secret[i] = net_secret[i];
54
55 md5_transform(hash, secret);
56
57 return seq_scale(hash[0]);
58 }
59 EXPORT_SYMBOL(secure_tcpv6_sequence_number);
60
secure_ipv6_port_ephemeral(const __be32 * saddr,const __be32 * daddr,__be16 dport)61 u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
62 __be16 dport)
63 {
64 u32 secret[MD5_MESSAGE_BYTES / 4];
65 u32 hash[MD5_DIGEST_WORDS];
66 u32 i;
67
68 memcpy(hash, saddr, 16);
69 for (i = 0; i < 4; i++)
70 secret[i] = net_secret[i] + (__force u32) daddr[i];
71 secret[4] = net_secret[4] + (__force u32)dport;
72 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
73 secret[i] = net_secret[i];
74
75 md5_transform(hash, secret);
76
77 return hash[0];
78 }
79 #endif
80
81 #ifdef CONFIG_INET
secure_ip_id(__be32 daddr)82 __u32 secure_ip_id(__be32 daddr)
83 {
84 u32 hash[MD5_DIGEST_WORDS];
85
86 hash[0] = (__force __u32) daddr;
87 hash[1] = net_secret[13];
88 hash[2] = net_secret[14];
89 hash[3] = net_secret[15];
90
91 md5_transform(hash, net_secret);
92
93 return hash[0];
94 }
95
secure_ipv6_id(const __be32 daddr[4])96 __u32 secure_ipv6_id(const __be32 daddr[4])
97 {
98 __u32 hash[4];
99
100 memcpy(hash, daddr, 16);
101 md5_transform(hash, net_secret);
102
103 return hash[0];
104 }
105
secure_tcp_sequence_number(__be32 saddr,__be32 daddr,__be16 sport,__be16 dport)106 __u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
107 __be16 sport, __be16 dport)
108 {
109 u32 hash[MD5_DIGEST_WORDS];
110
111 hash[0] = (__force u32)saddr;
112 hash[1] = (__force u32)daddr;
113 hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
114 hash[3] = net_secret[15];
115
116 md5_transform(hash, net_secret);
117
118 return seq_scale(hash[0]);
119 }
120
secure_ipv4_port_ephemeral(__be32 saddr,__be32 daddr,__be16 dport)121 u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
122 {
123 u32 hash[MD5_DIGEST_WORDS];
124
125 hash[0] = (__force u32)saddr;
126 hash[1] = (__force u32)daddr;
127 hash[2] = (__force u32)dport ^ net_secret[14];
128 hash[3] = net_secret[15];
129
130 md5_transform(hash, net_secret);
131
132 return hash[0];
133 }
134 EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
135 #endif
136
137 #if IS_ENABLED(CONFIG_IP_DCCP)
secure_dccp_sequence_number(__be32 saddr,__be32 daddr,__be16 sport,__be16 dport)138 u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
139 __be16 sport, __be16 dport)
140 {
141 u32 hash[MD5_DIGEST_WORDS];
142 u64 seq;
143
144 hash[0] = (__force u32)saddr;
145 hash[1] = (__force u32)daddr;
146 hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
147 hash[3] = net_secret[15];
148
149 md5_transform(hash, net_secret);
150
151 seq = hash[0] | (((u64)hash[1]) << 32);
152 seq += ktime_to_ns(ktime_get_real());
153 seq &= (1ull << 48) - 1;
154
155 return seq;
156 }
157 EXPORT_SYMBOL(secure_dccp_sequence_number);
158
159 #if IS_ENABLED(CONFIG_IPV6)
secure_dccpv6_sequence_number(__be32 * saddr,__be32 * daddr,__be16 sport,__be16 dport)160 u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
161 __be16 sport, __be16 dport)
162 {
163 u32 secret[MD5_MESSAGE_BYTES / 4];
164 u32 hash[MD5_DIGEST_WORDS];
165 u64 seq;
166 u32 i;
167
168 memcpy(hash, saddr, 16);
169 for (i = 0; i < 4; i++)
170 secret[i] = net_secret[i] + daddr[i];
171 secret[4] = net_secret[4] +
172 (((__force u16)sport << 16) + (__force u16)dport);
173 for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
174 secret[i] = net_secret[i];
175
176 md5_transform(hash, secret);
177
178 seq = hash[0] | (((u64)hash[1]) << 32);
179 seq += ktime_to_ns(ktime_get_real());
180 seq &= (1ull << 48) - 1;
181
182 return seq;
183 }
184 EXPORT_SYMBOL(secure_dccpv6_sequence_number);
185 #endif
186 #endif
187