Commit 6e5714ea authored by David S. Miller's avatar David S. Miller

net: Compute protocol sequence numbers and fragment IDs using MD5.

Computers have become a lot faster since we compromised on the
partial MD4 hash which we use currently for performance reasons.

MD5 is a much safer choice, and is inline with both RFC1948 and
other ISS generators (OpenBSD, Solaris, etc.)

Furthermore, only having 24-bits of the sequence number be truly
unpredictable is a very serious limitation.  So the periodic
regeneration and 8-bit counter have been removed.  We compute and
use a full 32-bit sequence number.

For ipv6, DCCP was found to use a 32-bit truncated initial sequence
number (it needs 43-bits) and that is fixed here as well.
Reported-by: default avatarDan Kaminsky <dan@doxpara.com>
Tested-by: default avatarWilly Tarreau <w@1wt.eu>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent bc0b96b5
This diff is collapsed.
...@@ -57,18 +57,6 @@ extern void add_interrupt_randomness(int irq); ...@@ -57,18 +57,6 @@ extern void add_interrupt_randomness(int irq);
extern void get_random_bytes(void *buf, int nbytes); extern void get_random_bytes(void *buf, int nbytes);
void generate_random_uuid(unsigned char uuid_out[16]); void generate_random_uuid(unsigned char uuid_out[16]);
extern __u32 secure_ip_id(__be32 daddr);
extern __u32 secure_ipv6_id(const __be32 daddr[4]);
extern u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport);
extern u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
__be16 dport);
extern __u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
__be16 sport, __be16 dport);
extern __u32 secure_tcpv6_sequence_number(__be32 *saddr, __be32 *daddr,
__be16 sport, __be16 dport);
extern u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
__be16 sport, __be16 dport);
#ifndef MODULE #ifndef MODULE
extern const struct file_operations random_fops, urandom_fops; extern const struct file_operations random_fops, urandom_fops;
#endif #endif
......
#ifndef _NET_SECURE_SEQ
#define _NET_SECURE_SEQ
#include <linux/types.h>
extern __u32 secure_ip_id(__be32 daddr);
extern __u32 secure_ipv6_id(const __be32 daddr[4]);
extern u32 secure_ipv4_port_ephemeral(__be32 saddr, __be32 daddr, __be16 dport);
extern u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr,
__be16 dport);
extern __u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr,
__be16 sport, __be16 dport);
extern __u32 secure_tcpv6_sequence_number(__be32 *saddr, __be32 *daddr,
__be16 sport, __be16 dport);
extern u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
__be16 sport, __be16 dport);
extern u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr,
__be16 sport, __be16 dport);
#endif /* _NET_SECURE_SEQ */
...@@ -3,7 +3,7 @@ ...@@ -3,7 +3,7 @@
# #
obj-y := sock.o request_sock.o skbuff.o iovec.o datagram.o stream.o scm.o \ obj-y := sock.o request_sock.o skbuff.o iovec.o datagram.o stream.o scm.o \
gen_stats.o gen_estimator.o net_namespace.o gen_stats.o gen_estimator.o net_namespace.o secure_seq.o
obj-$(CONFIG_SYSCTL) += sysctl_net_core.o obj-$(CONFIG_SYSCTL) += sysctl_net_core.o
......
#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 <net/secure_seq.h>
static u32 net_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;
static int __init net_secret_init(void)
{
get_random_bytes(net_secret, sizeof(net_secret));
return 0;
}
late_initcall(net_secret_init);
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);
}
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
__u32 secure_tcpv6_sequence_number(__be32 *saddr, __be32 *daddr,
__be16 sport, __be16 dport)
{
u32 secret[MD5_MESSAGE_BYTES / 4];
u32 hash[MD5_DIGEST_WORDS];
u32 i;
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);
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;
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];
}
#endif
#ifdef CONFIG_INET
__u32 secure_ip_id(__be32 daddr)
{
u32 hash[MD5_DIGEST_WORDS];
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];
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];
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];
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 defined(CONFIG_IP_DCCP) || defined(CONFIG_IP_DCCP_MODULE)
u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr,
__be16 sport, __be16 dport)
{
u32 hash[MD5_DIGEST_WORDS];
u64 seq;
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 defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
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;
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
...@@ -26,6 +26,7 @@ ...@@ -26,6 +26,7 @@
#include <net/timewait_sock.h> #include <net/timewait_sock.h>
#include <net/tcp_states.h> #include <net/tcp_states.h>
#include <net/xfrm.h> #include <net/xfrm.h>
#include <net/secure_seq.h>
#include "ackvec.h" #include "ackvec.h"
#include "ccid.h" #include "ccid.h"
......
...@@ -29,6 +29,7 @@ ...@@ -29,6 +29,7 @@
#include <net/transp_v6.h> #include <net/transp_v6.h>
#include <net/ip6_checksum.h> #include <net/ip6_checksum.h>
#include <net/xfrm.h> #include <net/xfrm.h>
#include <net/secure_seq.h>
#include "dccp.h" #include "dccp.h"
#include "ipv6.h" #include "ipv6.h"
...@@ -69,13 +70,7 @@ static inline void dccp_v6_send_check(struct sock *sk, struct sk_buff *skb) ...@@ -69,13 +70,7 @@ static inline void dccp_v6_send_check(struct sock *sk, struct sk_buff *skb)
dh->dccph_checksum = dccp_v6_csum_finish(skb, &np->saddr, &np->daddr); dh->dccph_checksum = dccp_v6_csum_finish(skb, &np->saddr, &np->daddr);
} }
static inline __u32 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr, static inline __u64 dccp_v6_init_sequence(struct sk_buff *skb)
__be16 sport, __be16 dport )
{
return secure_tcpv6_sequence_number(saddr, daddr, sport, dport);
}
static inline __u32 dccp_v6_init_sequence(struct sk_buff *skb)
{ {
return secure_dccpv6_sequence_number(ipv6_hdr(skb)->daddr.s6_addr32, return secure_dccpv6_sequence_number(ipv6_hdr(skb)->daddr.s6_addr32,
ipv6_hdr(skb)->saddr.s6_addr32, ipv6_hdr(skb)->saddr.s6_addr32,
......
...@@ -21,6 +21,7 @@ ...@@ -21,6 +21,7 @@
#include <net/inet_connection_sock.h> #include <net/inet_connection_sock.h>
#include <net/inet_hashtables.h> #include <net/inet_hashtables.h>
#include <net/secure_seq.h>
#include <net/ip.h> #include <net/ip.h>
/* /*
......
...@@ -19,6 +19,7 @@ ...@@ -19,6 +19,7 @@
#include <linux/net.h> #include <linux/net.h>
#include <net/ip.h> #include <net/ip.h>
#include <net/inetpeer.h> #include <net/inetpeer.h>
#include <net/secure_seq.h>
/* /*
* Theory of operations. * Theory of operations.
......
...@@ -12,6 +12,7 @@ ...@@ -12,6 +12,7 @@
#include <linux/ip.h> #include <linux/ip.h>
#include <linux/netfilter.h> #include <linux/netfilter.h>
#include <net/secure_seq.h>
#include <net/netfilter/nf_nat.h> #include <net/netfilter/nf_nat.h>
#include <net/netfilter/nf_nat_core.h> #include <net/netfilter/nf_nat_core.h>
#include <net/netfilter/nf_nat_rule.h> #include <net/netfilter/nf_nat_rule.h>
......
...@@ -109,6 +109,7 @@ ...@@ -109,6 +109,7 @@
#include <linux/sysctl.h> #include <linux/sysctl.h>
#endif #endif
#include <net/atmclip.h> #include <net/atmclip.h>
#include <net/secure_seq.h>
#define RT_FL_TOS(oldflp4) \ #define RT_FL_TOS(oldflp4) \
((u32)(oldflp4->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK))) ((u32)(oldflp4->flowi4_tos & (IPTOS_RT_MASK | RTO_ONLINK)))
......
...@@ -72,6 +72,7 @@ ...@@ -72,6 +72,7 @@
#include <net/timewait_sock.h> #include <net/timewait_sock.h>
#include <net/xfrm.h> #include <net/xfrm.h>
#include <net/netdma.h> #include <net/netdma.h>
#include <net/secure_seq.h>
#include <linux/inet.h> #include <linux/inet.h>
#include <linux/ipv6.h> #include <linux/ipv6.h>
......
...@@ -20,6 +20,7 @@ ...@@ -20,6 +20,7 @@
#include <net/inet_connection_sock.h> #include <net/inet_connection_sock.h>
#include <net/inet_hashtables.h> #include <net/inet_hashtables.h>
#include <net/inet6_hashtables.h> #include <net/inet6_hashtables.h>
#include <net/secure_seq.h>
#include <net/ip.h> #include <net/ip.h>
int __inet6_hash(struct sock *sk, struct inet_timewait_sock *tw) int __inet6_hash(struct sock *sk, struct inet_timewait_sock *tw)
......
...@@ -61,6 +61,7 @@ ...@@ -61,6 +61,7 @@
#include <net/timewait_sock.h> #include <net/timewait_sock.h>
#include <net/netdma.h> #include <net/netdma.h>
#include <net/inet_common.h> #include <net/inet_common.h>
#include <net/secure_seq.h>
#include <asm/uaccess.h> #include <asm/uaccess.h>
......
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