Commit 7cd23e53 authored by Jason A. Donenfeld's avatar Jason A. Donenfeld Committed by David S. Miller
Browse files

secure_seq: use SipHash in place of MD5 



This gives a clear speed and security improvement. Siphash is both
faster and is more solid crypto than the aging MD5.

Rather than manually filling MD5 buffers, for IPv6, we simply create
a layout by a simple anonymous struct, for which gcc generates
rather efficient code. For IPv4, we pass the values directly to the
short input convenience functions.

64-bit x86_64:
[    1.683628] secure_tcpv6_sequence_number_md5# cycles: 99563527
[    1.717350] secure_tcp_sequence_number_md5# cycles: 92890502
[    1.741968] secure_tcpv6_sequence_number_siphash# cycles: 67825362
[    1.762048] secure_tcp_sequence_number_siphash# cycles: 67485526

32-bit x86:
[    1.600012] secure_tcpv6_sequence_number_md5# cycles: 103227892
[    1.634219] secure_tcp_sequence_number_md5# cycles: 94732544
[    1.669102] secure_tcpv6_sequence_number_siphash# cycles: 96299384
[    1.700165] secure_tcp_sequence_number_siphash# cycles: 86015473

Signed-off-by: default avatarJason A. Donenfeld <Jason@zx2c4.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: David Miller <davem@davemloft.net>
Cc: David Laight <David.Laight@aculab.com>
Cc: Tom Herbert <tom@herbertland.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 1ae2324f

net/core/secure_seq.c

+63 −82
Original line number Diff line number Diff line 
/*

 * Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.

 */



#include <linux/kernel.h>

#include <linux/init.h>

#include <linux/cryptohash.h>
@@ -8,18 +12,18 @@ 
#include <linux/ktime.h>

#include <linux/string.h>

#include <linux/net.h>



#include <linux/siphash.h>

#include <net/secure_seq.h>



#if IS_ENABLED(CONFIG_IPV6) || IS_ENABLED(CONFIG_INET)

#include <linux/in6.h>

#include <net/tcp.h>

#define NET_SECRET_SIZE (MD5_MESSAGE_BYTES / 4)



static u32 net_secret[NET_SECRET_SIZE] ____cacheline_aligned;

static siphash_key_t net_secret __read_mostly;



static __always_inline void net_secret_init(void)

{

	net_get_random_once(net_secret, sizeof(net_secret));

	net_get_random_once(&net_secret, sizeof(net_secret));

}

#endif
@@ -44,80 +48,70 @@ static u32 seq_scale(u32 seq) 
u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr,

				 __be16 sport, __be16 dport, u32 *tsoff)

{

	u32 secret[MD5_MESSAGE_BYTES / 4];

	u32 hash[MD5_DIGEST_WORDS];

	u32 i;



	const struct {

		struct in6_addr saddr;

		struct in6_addr daddr;

		__be16 sport;

		__be16 dport;

	} __aligned(SIPHASH_ALIGNMENT) combined = {

		.saddr = *(struct in6_addr *)saddr,

		.daddr = *(struct in6_addr *)daddr,

		.sport = sport,

		.dport = dport

	};

	u64 hash;

	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);



	*tsoff = sysctl_tcp_timestamps == 1 ? hash[1] : 0;

	return seq_scale(hash[0]);

	hash = siphash(&combined, offsetofend(typeof(combined), dport),

		       &net_secret);

	*tsoff = sysctl_tcp_timestamps == 1 ? (hash >> 32) : 0;

	return seq_scale(hash);

}

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;



	const struct {

		struct in6_addr saddr;

		struct in6_addr daddr;

		__be16 dport;

	} __aligned(SIPHASH_ALIGNMENT) combined = {

		.saddr = *(struct in6_addr *)saddr,

		.daddr = *(struct in6_addr *)daddr,

		.dport = dport

	};

	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];

	return siphash(&combined, offsetofend(typeof(combined), dport),

		       &net_secret);

}

EXPORT_SYMBOL(secure_ipv6_port_ephemeral);

#endif



#ifdef CONFIG_INET



/* secure_tcp_sequence_number(a, b, 0, d) == secure_ipv4_port_ephemeral(a, b, d),

 * but fortunately, `sport' cannot be 0 in any circumstances. If this changes,

 * it would be easy enough to have the former function use siphash_4u32, passing

 * the arguments as separate u32.

 */



u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,

			       __be16 sport, __be16 dport, u32 *tsoff)

{

	u32 hash[MD5_DIGEST_WORDS];



	u64 hash;

	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);



	*tsoff = sysctl_tcp_timestamps == 1 ? hash[1] : 0;

	return seq_scale(hash[0]);

	hash = siphash_3u32((__force u32)saddr, (__force u32)daddr,

			    (__force u32)sport << 16 | (__force u32)dport,

			    &net_secret);

	*tsoff = sysctl_tcp_timestamps == 1 ? (hash >> 32) : 0;

	return seq_scale(hash);

}



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];

	return siphash_3u32((__force u32)saddr, (__force u32)daddr,

			    (__force u16)dport, &net_secret);

}

EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral);

#endif
@@ -126,21 +120,11 @@ EXPORT_SYMBOL_GPL(secure_ipv4_port_ephemeral); 
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 = siphash_3u32(saddr, daddr, (u32)sport << 16 | dport, &net_secret);

	seq += ktime_get_real_ns();

	seq &= (1ull << 48) - 1;



	return seq;

}

EXPORT_SYMBOL(secure_dccp_sequence_number);
@@ -149,26 +133,23 @@ EXPORT_SYMBOL(secure_dccp_sequence_number); 
u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,

				  __be16 sport, __be16 dport)

{

	u32 secret[MD5_MESSAGE_BYTES / 4];

	u32 hash[MD5_DIGEST_WORDS];

	const struct {

		struct in6_addr saddr;

		struct in6_addr daddr;

		__be16 sport;

		__be16 dport;

	} __aligned(SIPHASH_ALIGNMENT) combined = {

		.saddr = *(struct in6_addr *)saddr,

		.daddr = *(struct in6_addr *)daddr,

		.sport = sport,

		.dport = dport

	};

	u64 seq;

	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);



	seq = hash[0] | (((u64)hash[1]) << 32);

	seq = siphash(&combined, offsetofend(typeof(combined), dport),

		      &net_secret);

	seq += ktime_get_real_ns();

	seq &= (1ull << 48) - 1;



	return seq;

}

EXPORT_SYMBOL(secure_dccpv6_sequence_number);

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