svn commit: r342925 - head/sys/netpfil/ipfw

[Andrey V. Elsukov]

Author: ae
Date: Fri Jan 11 01:54:15 2019
New Revision: 342925
URL: https://svnweb.freebsd.org/changeset/base/342925

Log:
  Relax requirement to packet size of CARP protocol and remove version check.
  
  CARP shares protocol number 112 with VRRP (RFC 5798). And the size of
  VRRP packet may be smaller than CARP. ipfw_chk() does m_pullup() to at
  least sizeof(struct carp_header) and can fail when packet is VRRP. This
  leads to packet drop and message about failed pullup attempt.
  Also, RFC 5798 defines version 3 of VRRP protocol, this version number
  also unsupported by CARP and such check leads to packet drop.
  
  carp_input() does its own checks for protocol version and packet size,
  so we can remove these checks to be able pass VRRP packets.
  
  PR:		234207
  MFC after:	1 week

Modified:
  head/sys/netpfil/ipfw/ip_fw2.c

Modified: head/sys/netpfil/ipfw/ip_fw2.c
==============================================================================
--- head/sys/netpfil/ipfw/ip_fw2.c	Fri Jan 11 01:42:47 2019	(r342924)
+++ head/sys/netpfil/ipfw/ip_fw2.c	Fri Jan 11 01:54:15 2019	(r342925)
@@ -1591,12 +1591,10 @@ do {								\
 				break;
 
 			case IPPROTO_CARP:
-				PULLUP_TO(hlen, ulp, struct carp_header);
-				if (((struct carp_header *)ulp)->carp_version !=
-				    CARP_VERSION) 
-					return (IP_FW_DENY);
-				if (((struct carp_header *)ulp)->carp_type !=
-				    CARP_ADVERTISEMENT) 
+				PULLUP_TO(hlen, ulp, offsetof(
+				    struct carp_header, carp_counter));
+				if (CARP_ADVERTISEMENT !=
+				    ((struct carp_header *)ulp)->carp_type)
 					return (IP_FW_DENY);
 				break;