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 #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_to_ns(ktime_get_real()) >> 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 __u32 secure_ip_id(__be32 daddr)
  89 {
  90         u32 hash[MD5_DIGEST_WORDS];
  91
  92         net_secret_init();
  93         hash[0] = (__force __u32) daddr;
  94         hash[1] = net_secret[13];
  95         hash[2] = net_secret[14];
  96         hash[3] = net_secret[15];
  97
  98         md5_transform(hash, net_secret);
  99
 100         return hash[0];
 101 }
 102
 103 __u32 secure_ipv6_id(const __be32 daddr[4])
 104 {
 105         __u32 hash[4];
 106
 107         net_secret_init();
 108         memcpy(hash, daddr, 16);
 109         md5_transform(hash, net_secret);
 110
 111         return hash[0];
 112 }
 113
 114 __u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
 115                                  __be16 sport, __be16 dport)
 116 {
 117         u32 hash[MD5_DIGEST_WORDS];
 118
 119         net_secret_init();
 120         hash[0] = (__force u32)saddr;
 121         hash[1] = (__force u32)daddr;
 122         hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
 123         hash[3] = net_secret[15];
 124
 125         md5_transform(hash, net_secret);
 126
 127         return seq_scale(hash[0]);
 128 }
 129
 130 u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
 131 {
 132         u32 hash[MD5_DIGEST_WORDS];
 133
 134         net_secret_init();
 135         hash[0] = (__force u32)saddr;
 136         hash[1] = (__force u32)daddr;
 137         hash[2] = (__force u32)dport ^ net_secret[14];
 138         hash[3] = net_secret[15];
 139
 140         md5_transform(hash, net_secret);
 141
 142         return hash[0];
 143 }
 144 EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
 145 #endif
 146
 147 #if IS_ENABLED(CONFIG_IP_DCCP)
 148 u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
 149                                 __be16 sport, __be16 dport)
 150 {
 151         u32 hash[MD5_DIGEST_WORDS];
 152         u64 seq;
 153
 154         net_secret_init();
 155         hash[0] = (__force u32)saddr;
 156         hash[1] = (__force u32)daddr;
 157         hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
 158         hash[3] = net_secret[15];
 159
 160         md5_transform(hash, net_secret);
 161
 162         seq = hash[0] | (((u64)hash[1]) << 32);
 163         seq += ktime_to_ns(ktime_get_real());
 164         seq &= (1ull << 48) - 1;
 165
 166         return seq;
 167 }
 168 EXPORT_SYMBOL(secure_dccp_sequence_number);
 169
 170 #if IS_ENABLED(CONFIG_IPV6)
 171 u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
 172                                   __be16 sport, __be16 dport)
 173 {
 174         u32 secret[MD5_MESSAGE_BYTES / 4];
 175         u32 hash[MD5_DIGEST_WORDS];
 176         u64 seq;
 177         u32 i;
 178
 179         net_secret_init();
 180         memcpy(hash, saddr, 16);
 181         for (i = 0; i < 4; i++)
 182                 secret[i] = net_secret[i] + daddr[i];
 183         secret[4] = net_secret[4] +
 184                 (((__force u16)sport << 16) + (__force u16)dport);
 185         for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
 186                 secret[i] = net_secret[i];
 187
 188         md5_transform(hash, secret);
 189
 190         seq = hash[0] | (((u64)hash[1]) << 32);
 191         seq += ktime_to_ns(ktime_get_real());
 192         seq &= (1ull << 48) - 1;
 193
 194         return seq;
 195 }
 196 EXPORT_SYMBOL(secure_dccpv6_sequence_number);
 197 #endif
 198 #endif