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#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/cryptohash.h>
#include <linux/module.h>
#include <linux/cache.h>
#include <linux/random.h>
#include <linux/hrtimer.h>
#include <linux/ktime.h>
#include <linux/string.h>
#include <linux/net.h>
#include <net/secure_seq.h>
#define NET_SECRET_SIZE (MD5_MESSAGE_BYTES / 4)
static u32 net_secret[NET_SECRET_SIZE] ____cacheline_aligned;
static void net_secret_init(void)
{
net_get_random_once(net_secret, sizeof(net_secret));
}
#ifdef CONFIG_INET
static u32 seq_scale(u32 seq)
{
/*
* As close as possible to RFC 793, which
* suggests using a 250 kHz clock.
* Further reading shows this assumes 2 Mb/s networks.
* For 10 Mb/s Ethernet, a 1 MHz clock is appropriate.
* For 10 Gb/s Ethernet, a 1 GHz clock should be ok, but
* we also need to limit the resolution so that the u32 seq
* overlaps less than one time per MSL (2 minutes).
* Choosing a clock of 64 ns period is OK. (period of 274 s)
*/
return seq + (ktime_to_ns(ktime_get_real()) >> 6);
}
#endif
#if IS_ENABLED(CONFIG_IPV6)
__u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,
__be16 sport, __be16 dport)
{
u32 secret[MD5_MESSAGE_BYTES / 4];
u32 hash[MD5_DIGEST_WORDS];
u32 i;
net_secret_init();
memcpy(hash, saddr, 16);
for (i = 0; i < 4; i++)
secret[i] = net_secret[i] + (__force u32)daddr[i];
secret[4] = net_secret[4] +
(((__force u16)sport << 16) + (__force u16)dport);
for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
secret[i] = net_secret[i];
md5_transform(hash, secret);
return seq_scale(hash[0]);
}
EXPORT_SYMBOL(secure_tcpv6_sequence_number);
u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
__be16 dport)
{
u32 secret[MD5_MESSAGE_BYTES / 4];
u32 hash[MD5_DIGEST_WORDS];
u32 i;
net_secret_init();
memcpy(hash, saddr, 16);
for (i = 0; i < 4; i++)
secret[i] = net_secret[i] + (__force u32) daddr[i];
secret[4] = net_secret[4] + (__force u32)dport;
for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
secret[i] = net_secret[i];
md5_transform(hash, secret);
return hash[0];
}
EXPORT_SYMBOL(secure_ipv6_port_ephemeral);
#endif
#ifdef CONFIG_INET
__u32 secure_ip_id(__be32 daddr)
{
u32 hash[MD5_DIGEST_WORDS];
net_secret_init();
hash[0] = (__force __u32) daddr;
hash[1] = net_secret[13];
hash[2] = net_secret[14];
hash[3] = net_secret[15];
md5_transform(hash, net_secret);
return hash[0];
}
__u32 secure_ipv6_id(const __be32 daddr[4])
{
__u32 hash[4];
net_secret_init();
memcpy(hash, daddr, 16);
md5_transform(hash, net_secret);
return hash[0];
}
__u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
__be16 sport, __be16 dport)
{
u32 hash[MD5_DIGEST_WORDS];
net_secret_init();
hash[0] = (__force u32)saddr;
hash[1] = (__force u32)daddr;
hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
hash[3] = net_secret[15];
md5_transform(hash, net_secret);
return seq_scale(hash[0]);
}
u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport)
{
u32 hash[MD5_DIGEST_WORDS];
net_secret_init();
hash[0] = (__force u32)saddr;
hash[1] = (__force u32)daddr;
hash[2] = (__force u32)dport ^ net_secret[14];
hash[3] = net_secret[15];
md5_transform(hash, net_secret);
return hash[0];
}
EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);
#endif
#if IS_ENABLED(CONFIG_IP_DCCP)
u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
__be16 sport, __be16 dport)
{
u32 hash[MD5_DIGEST_WORDS];
u64 seq;
net_secret_init();
hash[0] = (__force u32)saddr;
hash[1] = (__force u32)daddr;
hash[2] = ((__force u16)sport << 16) + (__force u16)dport;
hash[3] = net_secret[15];
md5_transform(hash, net_secret);
seq = hash[0] | (((u64)hash[1]) << 32);
seq += ktime_to_ns(ktime_get_real());
seq &= (1ull << 48) - 1;
return seq;
}
EXPORT_SYMBOL(secure_dccp_sequence_number);
#if IS_ENABLED(CONFIG_IPV6)
u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
__be16 sport, __be16 dport)
{
u32 secret[MD5_MESSAGE_BYTES / 4];
u32 hash[MD5_DIGEST_WORDS];
u64 seq;
u32 i;
net_secret_init();
memcpy(hash, saddr, 16);
for (i = 0; i < 4; i++)
secret[i] = net_secret[i] + daddr[i];
secret[4] = net_secret[4] +
(((__force u16)sport << 16) + (__force u16)dport);
for (i = 5; i < MD5_MESSAGE_BYTES / 4; i++)
secret[i] = net_secret[i];
md5_transform(hash, secret);
seq = hash[0] | (((u64)hash[1]) << 32);
seq += ktime_to_ns(ktime_get_real());
seq &= (1ull << 48) - 1;
return seq;
}
EXPORT_SYMBOL(secure_dccpv6_sequence_number);
#endif
#endif
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