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