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