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Commit 9a3bab6b authored by Eric Dumazet's avatar Eric Dumazet Committed by David S. Miller
Browse files

net: net_secret should not depend on TCP 



A host might need net_secret[] and never open a single socket.

Problem added in commit aebda156
("net: defer net_secret[] initialization")

Based on prior patch from Hannes Frederic Sowa.

Reported-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarHannes Frederic Sowa <hannes@strressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 50624c93

include/net/secure_seq.h

+0 −1
Original line number Diff line number Diff line
@@ -3,7 +3,6 @@ 


#include <linux/types.h>



extern void net_secret_init(void);

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);

net/core/secure_seq.c

+24 −3
Original line number Diff line number Diff line
@@ -10,11 +10,24 @@ 


#include <net/secure_seq.h>



static u32 net_secret[MD5_MESSAGE_BYTES / 4] ____cacheline_aligned;

#define NET_SECRET_SIZE (MD5_MESSAGE_BYTES / 4)



void net_secret_init(void)

static u32 net_secret[NET_SECRET_SIZE] ____cacheline_aligned;



static void net_secret_init(void)

{

	get_random_bytes(net_secret, sizeof(net_secret));

	u32 tmp;

	int i;



	if (likely(net_secret[0]))

		return;



	for (i = NET_SECRET_SIZE; i > 0;) {

		do {

			get_random_bytes(&tmp, sizeof(tmp));

		} while (!tmp);

		cmpxchg(&net_secret[--i], 0, tmp);

	}

}



#ifdef CONFIG_INET
@@ -42,6 +55,7 @@ __u32 secure_tcpv6_sequence_number(const __be32 *saddr, const __be32 *daddr, 
	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];
@@ -63,6 +77,7 @@ u32 secure_ipv6_port_ephemeral(const __be32 *saddr, const __be32 *daddr, 
	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];
@@ -82,6 +97,7 @@ __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];
@@ -96,6 +112,7 @@ __u32 secure_ipv6_id(const __be32 daddr[4]) 
{

	__u32 hash[4];



	net_secret_init();

	memcpy(hash, daddr, 16);

	md5_transform(hash, net_secret);
@@ -107,6 +124,7 @@ __u32 secure_tcp_sequence_number(__be32 saddr, __be32 daddr, 
{

	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;
@@ -121,6 +139,7 @@ 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];
@@ -140,6 +159,7 @@ u64 secure_dccp_sequence_number(__be32 saddr, __be32 daddr, 
	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;
@@ -164,6 +184,7 @@ u64 secure_dccpv6_sequence_number(__be32 *saddr, __be32 *daddr, 
	u64 seq;

	u32 i;



	net_secret_init();

	memcpy(hash, saddr, 16);

	for (i = 0; i < 4; i++)

		secret[i] = net_secret[i] + daddr[i];

net/ipv4/af_inet.c

+1 −3
Original line number Diff line number Diff line
@@ -263,10 +263,8 @@ void build_ehash_secret(void) 
		get_random_bytes(&rnd, sizeof(rnd));

	} while (rnd == 0);



	if (cmpxchg(&inet_ehash_secret, 0, rnd) == 0) {

	if (cmpxchg(&inet_ehash_secret, 0, rnd) == 0)

		get_random_bytes(&ipv6_hash_secret, sizeof(ipv6_hash_secret));

		net_secret_init();

	}

}

EXPORT_SYMBOL(build_ehash_secret);