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Prevent TCP blind data attacks by not allowing non-initial fragments to 

start at less than 68 bytes (minimal fragment size).
This commit is contained in:
matt 2007-12-21 18:58:55 +00:00
parent c48902ebaf
commit 6f23ff186c
1 changed files with 13 additions and 3 deletions
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16
sys/netinet/ip_input.c
View File

@ -1,4 +1,4 @@
/* $NetBSD: ip_input.c,v 1.257 2007/12/20 19:53:32 dyoung Exp $ */
/* $NetBSD: ip_input.c,v 1.258 2007/12/21 18:58:55 matt Exp $ */
/*
* Copyright (C) 1995, 1996, 1997, and 1998 WIDE Project.
@ -98,7 +98,7 @@
*/
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ip_input.c,v 1.257 2007/12/20 19:53:32 dyoung Exp $");
__KERNEL_RCSID(0, "$NetBSD: ip_input.c,v 1.258 2007/12/21 18:58:55 matt Exp $");
#include "opt_inet.h"
#include "opt_gateway.h"
@ -896,7 +896,17 @@ ours:
* but it's not worth the time; just let them time out.)
*/
if (ip->ip_off & ~htons(IP_DF|IP_RF)) {
uint16_t off;
/*
* Prevent TCP blind data attacks by not allowing non-initial
* fragments to start at less than 68 bytes (minimal fragment
* size).
*/
off = htons(ip->ip_off) & ~(IP_DF|IP_EF|IP_MF);
if (off > 0 && off + hlen < IP_MINFRAGSIZE - 1) {
ipstat.ips_badfrags++;
goto bad;
}
/*
* Look for queue of fragments
* of this datagram.