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net: net_secret should not depend on TCP 

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

Problem added in commit aebda156a5
("net: defer net_secret[] initialization")

Based on prior patch from Hannes Frederic Sowa.

Reported-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Hannes Frederic Sowa <hannes@strressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet 2013-09-24 06:19:57 -07:00 committed by David S. Miller
parent 50624c934d
commit 9a3bab6b05
3 changed files with 25 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/net/secure_seq.h
View File

@ -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);

27
net/core/secure_seq.c
View File

@ -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];

4
net/ipv4/af_inet.c
View File

@ -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);