net/core/secure_seq.c

   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 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 static 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 }
  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 #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
 119 u32 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 }
 132 EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
 133 #endif
 134
 135 #if defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE)
 136 u64 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 }
 155 EXPORT_SYMBOL(secure_dccp_sequence_number);
 156
 157 #if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
 158 u64 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 }
 182 EXPORT_SYMBOL(secure_dccpv6_sequence_number);
 183 #endif
 184 #endif