svn commit: r314111 - head/contrib/blacklist/libexec

[Kurt Lidl]

Author: lidl
Date: Wed Feb 22 21:50:37 2017
New Revision: 314111
URL: https://svnweb.freebsd.org/changeset/base/314111

Log:
  Improve ipfw rule creation for blacklist-helper script
  
  When blocking an address, the blacklist-helper script
  needs to do the following things for the ipfw packet
  filter:
  
   - create a table to hold the addresses to be blocked,
     so lookups can be done quickly, and place the address
     to be blocked in that table
   - create rule that does the lookup in the table and
     blocks the packet
  
  The ipfw system allows multiple rules to be inserted for
  a given rule number.  There only needs to be one rule
  to do the lookup per port.  Modify the script to probe
  for the existence of the rule before attempting to create
  it, so only one rule is inserted, rather than one rule per
  blocked address.
  
  PR:		214980
  Reported by:	azhegalov (at) gmail.com
  Reviewed by:	emaste
  MFC after:	3 days
  Sponsored by:	The FreeBSD Foundation
  Differential Revision:	https://reviews.freebsd.org/D9681

Modified:
  head/contrib/blacklist/libexec/blacklistd-helper

Modified: head/contrib/blacklist/libexec/blacklistd-helper
==============================================================================
--- head/contrib/blacklist/libexec/blacklistd-helper	Wed Feb 22 20:47:25 2017	(r314110)
+++ head/contrib/blacklist/libexec/blacklistd-helper	Wed Feb 22 21:50:37 2017	(r314111)
@@ -63,8 +63,11 @@ add)
 		tname="port$6"
 		/sbin/ipfw table $tname create type addr 2>/dev/null
 		/sbin/ipfw -q table $tname add "$addr/$mask"
-		/sbin/ipfw -q add $rule drop $3 from "table("$tname")" to \
-		    any dst-port $6 && echo OK
+		# if rule number $rule does not already exist, create it
+		/sbin/ipfw show $rule >/dev/null 2>&1 || \
+			/sbin/ipfw add $rule drop $3 from \
+			table"("$tname")" to any dst-port $6 >/dev/null && \
+			echo OK
 		;;
 	npf)
 		/sbin/npfctl rule "$2" add block in final $proto from \