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Commit 2051f11f authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
Browse files

[TCP]: Shrink syncookie_secret by 8 byte. 



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: default avatarFlorian Westphal <fw@strlen.de>
Acked-by: default avatarGlenn Griffin <ggriffin.kernel@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 310afe86

include/net/tcp.h

+1 −1
Original line number Diff line number Diff line
@@ -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,

net/ipv4/syncookies.c

+2 −2
Original line number Diff line number Diff line
@@ -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;

net/ipv6/syncookies.c

+1 −1
Original line number Diff line number Diff line
@@ -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)