Skip to content

Commit

Permalink
secure_seq: use SipHash in place of MD5
Browse files Browse the repository at this point in the history 
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: Jason 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: David S. Miller <davem@davemloft.net>
  • Loading branch information
@zx2c4 @davem330
zx2c4 authored and davem330 committed Jan 9, 2017
1 parent 1ae2324 commit 7cd23e5
Showing 1 changed file with 63 additions and 82 deletions.
145 changes: 63 additions & 82 deletions net/core/secure_seq.c
View file
Original file line number Diff line number Diff line change
@@ -1,3 +1,7 @@
/*
* Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
*/

#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/cryptohash.h>
Expand All @@ -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

Expand All @@ -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
Expand All @@ -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);
Expand All @@ -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);
Expand Down

0 comments on commit 7cd23e5

Please sign in to comment.