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[TCP]: Shrink syncookie_secret by 8 byte.

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the first u32 copied from syncookie_secret is overwritten by the
minute-counter four lines below.  After adjusting the destination
address, the size of syncookie_secret can be reduced accordingly.

AFAICS, the only other user of syncookie_secret[] is the ipv6
syncookie support.  Because ipv6 syncookies only grab 44 bytes from
syncookie_secret[], this shouldn't affect them in any way.

With fixes from Glenn Griffin.

Signed-off-by: Florian Westphal <fw@strlen.de>
Acked-by: Glenn Griffin <ggriffin.kernel@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Florian Westphal 2008-03-23 22:21:28 -07:00 committed by David S. Miller
parent 310afe86af
commit 2051f11fb8
3 changed files with 4 additions and 4 deletions
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2
include/net/tcp.h
View File

@ -436,7 +436,7 @@ extern int tcp_disconnect(struct sock *sk, int flags);
extern void tcp_unhash(struct sock *sk);
/* From syncookies.c */
extern __u32 syncookie_secret[2][16-3+SHA_DIGEST_WORDS];
extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
struct ip_options *opt);
extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,

4
net/ipv4/syncookies.c
View File

@ -21,7 +21,7 @@
extern int sysctl_tcp_syncookies;
__u32 syncookie_secret[2][16-3+SHA_DIGEST_WORDS];
__u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
EXPORT_SYMBOL(syncookie_secret);
static __init int init_syncookies(void)
@ -41,7 +41,7 @@ static u32 cookie_hash(__be32 saddr, __be32 daddr, __be16 sport, __be16 dport,
{
__u32 *tmp = __get_cpu_var(cookie_scratch);
memcpy(tmp + 3, syncookie_secret[c], sizeof(syncookie_secret[c]));
memcpy(tmp + 4, syncookie_secret[c], sizeof(syncookie_secret[c]));
tmp[0] = (__force u32)saddr;
tmp[1] = (__force u32)daddr;
tmp[2] = ((__force u32)sport << 16) + (__force u32)dport;

2
net/ipv6/syncookies.c
View File

@ -22,7 +22,7 @@
#include <net/tcp.h>
extern int sysctl_tcp_syncookies;
extern __u32 syncookie_secret[2][16-3+SHA_DIGEST_WORDS];
extern __u32 syncookie_secret[2][16-4+SHA_DIGEST_WORDS];
#define COOKIEBITS 24 /* Upper bits store count */
#define COOKIEMASK (((__u32)1 << COOKIEBITS) - 1)