Implement INPUT SNAT

Signed-off-by: Tom Eastep <teastep@shorewall.net>

Shorewall-core/lib.cli

@@ -25,7 +25,7 @@
 # loaded after this one and replaces some of the functions declared here.
 #
 
-SHOREWALL_CAPVERSION=50106
+SHOREWALL_CAPVERSION=50112
 
 if [ -z "$g_basedir" ]; then
     #
@@ -2863,6 +2863,7 @@ determine_capabilities() {
 		qt $g_tool -t nat -A $chain -j NETMAP --to 2001:470:B:227::/64 && NETMAP_TARGET=Yes
 	    fi
 	    qt $g_tool -t nat -A $chain -j MASQUERADE && MASQUERADE_TGT=Yes
+	    qt $g_tool -t nat -L INPUT -n && NAT_INPUT_CHAIN=Yes
 	    qt $g_tool -t nat -A $chain -p udplite -m multiport --dport 33 -j REDIRECT --to-port 22 && UDPREDIRECT=Yes
 	    qt $g_tool -t nat -F $chain
 	    qt $g_tool -t nat -X $chain
@@ -3331,6 +3332,7 @@ report_capabilities_unsorted() {
     report_capability "NFQUEUE CPU Fanout (CPU_FANOUT)" $CPU_FANOUT
     report_capability "NETMAP Target (NETMAP_TARGET)" $NETMAP_TARGET
     report_capability "--nflog-size support (NFLOG_SIZE)" $NFLOG_SIZE
+    report_capability "INPUT chain in nat table (NAT_INPUT_CHAIN)" $NAT_INPUT_CHAIN
 
     echo "   Kernel Version (KERNELVERSION): $KERNELVERSION"
     echo "   Capabilities Version (CAPVERSION): $CAPVERSION"
@@ -3439,6 +3441,7 @@ report_capabilities_unsorted1() {
     report_capability1 NETMAP_TARGET
     report_capability1 NFLOG_SIZE
     report_capability1 RESTORE_WAIT_OPTION
+    report_capability1 NAT_INPUT_CHAIN
 
     report_capability1 AMANDA_HELPER
     report_capability1 FTP_HELPER

Shorewall/Perl/Shorewall/Chains.pm

@@ -3182,6 +3182,8 @@ sub initialize_chain_table($) {
 	    new_builtin_chain 'nat', $chain, 'ACCEPT';
 	}
 
+	new_builtin_chain 'nat', 'INPUT', 'ACCEPT' if have_capability('NAT_INPUT_CHAIN');
+
 	for my $chain ( qw(PREROUTING INPUT OUTPUT ) ) {
 	    new_builtin_chain 'mangle', $chain, 'ACCEPT';
 	}
@@ -3244,6 +3246,8 @@ sub initialize_chain_table($) {
 	    new_builtin_chain 'nat', $chain, 'ACCEPT';
 	}
 
+	new_builtin_chain 'nat', 'INPUT', 'ACCEPT' if have_capability('NAT_INPUT_CHAIN');
+
 	for my $chain ( qw(PREROUTING INPUT OUTPUT FORWARD POSTROUTING ) ) {
 	    new_builtin_chain 'mangle', $chain, 'ACCEPT';
 	}

Shorewall/Perl/Shorewall/Config.pm

@@ -496,6 +496,7 @@ our %capdesc = ( NAT_ENABLED     => 'NAT',
                  NFLOG_SIZE      => '--nflog-size support',
 		 RESTORE_WAIT_OPTION
 				 => 'iptables-restore --wait option',
+                 NAT_INPUT_CHAIN => 'INPUT chain in NAT table',
 		 AMANDA_HELPER   => 'Amanda Helper',
 		 FTP_HELPER      => 'FTP Helper',
 		 FTP0_HELPER     => 'FTP-0 Helper',
@@ -835,7 +836,7 @@ sub initialize( $;$$$) {
 		    EXPORT                  => 0,
 		    KLUDGEFREE              => '',
 		    VERSION                 => "5.1.8-Beta1",
-		    CAPVERSION              => 50106 ,
+		    CAPVERSION              => 50112 ,
 		    BLACKLIST_LOG_TAG       => '',
 		    RELATED_LOG_TAG         => '',
 		    MACLIST_LOG_TAG         => '',
@@ -1129,6 +1130,7 @@ sub initialize( $;$$$) {
 	       NETMAP_TARGET => undef,
 	       NFLOG_SIZE => undef,
 	       RESTORE_WAIT_OPTION => undef,
+	       NAT_INPUT_CHAIN => undef,
 
 	       AMANDA_HELPER => undef,
 	       FTP_HELPER => undef,
@@ -4446,6 +4448,12 @@ sub Nat_Enabled() {
     qt1( "$iptables $iptablesw -t nat -L -n" );
 }
 
+sub Nat_Input_Chain {
+    have_capability( 'NAT_ENABLED' ) || return '';
+
+    qt1( "$iptables $iptablesw -t nat -L INPUT -n" );
+}
+
 sub Persistent_Snat() {
     have_capability( 'NAT_ENABLED' ) || return '';
 
@@ -5091,6 +5099,7 @@ our %detect_capability =
       MASQUERADE_TGT => \&Masquerade_Tgt,
       MULTIPORT => \&Multiport,
       NAT_ENABLED => \&Nat_Enabled,
+      NAT_INPUT_CHAIN => \&Nat_Input_Chain,
       NETBIOS_NS_HELPER => \&Netbios_ns_Helper,
       NETMAP_TARGET => \&Netmap_Target,
       NEW_CONNTRACK_MATCH => \&New_Conntrack_Match,
@@ -5190,6 +5199,7 @@ sub determine_capabilities() {
 	#
 	$capabilities{NAT_ENABLED}     = detect_capability( 'NAT_ENABLED' );
 	$capabilities{PERSISTENT_SNAT} = detect_capability( 'PERSISTENT_SNAT' );
+	$capabilities{NAT_INPUT_CHAIN} = detect_capability( 'NAT_INPUT_CHAIN' );
 	$capabilities{MANGLE_ENABLED}  = detect_capability( 'MANGLE_ENABLED' );
 
 	if ( $capabilities{CONNTRACK_MATCH} = detect_capability( 'CONNTRACK_MATCH' ) ) {

Shorewall/Perl/Shorewall/Rules.pm

@@ -5501,22 +5501,6 @@ sub process_snat1( $$$$$$$$$$$$ ) {
 	$interfaces    = $dest;
     }
     #
-    # Handle IPSEC options, if any
-    #
-    if ( $ipsec ne '-' ) {
-	fatal_error "Non-empty IPSEC column requires policy match support in your kernel and iptables"  unless have_capability( 'POLICY_MATCH' );
-
-	if ( $ipsec =~ /^yes$/i ) {
-	    $baserule .= do_ipsec_options 'out', 'ipsec', '';
-	} elsif ( $ipsec =~ /^no$/i ) {
-	    $baserule .= do_ipsec_options 'out', 'none', '';
-	} else {
-	    $baserule .= do_ipsec_options 'out', 'ipsec', $ipsec;
-	}
-    } elsif ( have_ipsec ) {
-	$baserule .= '-m policy --pol none --dir out ';
-    }
-    #
     # Handle Protocol, Ports and Condition
     #
     $baserule .= do_proto( $proto, $ports, '' );
@@ -5527,7 +5511,9 @@ sub process_snat1( $$$$$$$$$$$$ ) {
     $baserule .= do_user( $user )                    if $user ne '-';
     $baserule .= do_probability( $probability )      if $probability ne '-';
 
-    for my $fullinterface ( split_list( $interfaces, 'interface' ) ) {
+    my @interfaces = split_list( $interfaces, 'interface' );
+
+    for my $fullinterface ( @interfaces ) {
  
 	my $rule = '';
 	my $saveaddresses = $addresses;
@@ -5535,9 +5521,21 @@ sub process_snat1( $$$$$$$$$$$$ ) {
 	my $savebaserule  = $baserule;
 	my $interface = $fullinterface;
 
-	$interface =~ s/:.*//;   #interface name may include 'alias'
+	if ( $inaction ) {
+	    $interface =~ s/:.*// if $family == F_IPV4;   #interface name may include 'alias'
+	} else {
+	    if ( $interface eq firewall_zone ) {
+		if ( @interfaces == 1 ) {
+		    fatal_error q('+' not valid when the DEST is $FW) if $pre_nat;
+		    fatal_error q('MASQUERADE' not allowed when DEST is $FW) if $action eq 'MASQUERADE';
+		    require_capability 'NAT_INPUT_CHAIN', '$FW in the DEST column', 's';
+		    $interface = '';
+		} else {
+		    fatal_error q($FW may not appear in a list of interfaces);
+		}
+	    } else {
+		$interface =~ s/:.*// if $family == F_IPV4;   #interface name may include 'alias'
 
-	unless ( $inaction ) {
 		if ( $interface =~ /(.*)[(](\w*)[)]$/ ) {
 		    $interface    = $1;
 		    my $provider  = $2;
@@ -5560,11 +5558,34 @@ sub process_snat1( $$$$$$$$$$$$ ) {
 		    $rule .= match_dest_dev( $interface );
 		    $interface = $interfaceref->{name};
 		}
+	    }
 
-	    $chainref = ensure_chain('nat', $pre_nat ? snat_chain $interface : masq_chain $interface);
+	    $chainref = $interface ? ensure_chain('nat',  $pre_nat ? snat_chain $interface : masq_chain $interface) : $nat_table->{INPUT};
 	}
 
 	$baserule .= do_condition( $condition , $chainref->{name} );
+	#
+	# Handle IPSEC options, if any
+	#
+	if ( $ipsec ne '-' ) {
+	    fatal_error "Non-empty IPSEC column requires policy match support in your kernel and iptables"  unless have_capability( 'POLICY_MATCH' );
+
+	    my $dir = $interface ? 'out' : 'in';
+
+	    if ( $ipsec =~ /^yes$/i ) {
+		$baserule .= do_ipsec_options $dir, 'ipsec', '';
+	    } elsif ( $ipsec =~ /^no$/i ) {
+		$baserule .= do_ipsec_options $dir, 'none', '';
+	    } else {
+		$baserule .= do_ipsec_options $dir, 'ipsec', $ipsec;
+	    }
+	} elsif ( have_ipsec ) {
+	    if ( $interface ) {
+		$baserule .= '-m policy --pol none --dir out ';
+	    } else {
+		$baserule .= '-m policy --pol none --dir in ';
+	    }
+	}
 
 	my $detectaddress = 0;
 	my $exceptionrule = '';
@@ -5572,6 +5593,7 @@ sub process_snat1( $$$$$$$$$$$$ ) {
 
 	if ( $action eq 'SNAT' ) {
 	    if ( $addresses eq 'detect' ) {
+		fatal_error q('detect' not allowed when the destination is $FW) unless $interface;
 		my $variable = get_interface_address $interface;
 		$target .= " --to-source $variable";
 
@@ -5698,6 +5720,7 @@ sub process_snat1( $$$$$$$$$$$$ ) {
 		$target .= $addrlist;
 	    }
 	} elsif ( $action eq 'MASQUERADE' ) {
+	    fatal_error q('MASQUERADE' not allowed when the destination is $FW') unless $interface;
 	    if ( supplied $addresses ) {
 		validate_portpair1($proto, $addresses );
 		$target .= " --to-ports $addresses";
@@ -5715,7 +5738,7 @@ sub process_snat1( $$$$$$$$$$$$ ) {
 				 $params,
 				 $loglevel,
 				 $source,
-				 supplied( $destnets ) && $destnets ne '-' ? $inaction ? $destnets : join( ':', $interface, $destnets ) : $inaction ? '-' : $interface,
+				 supplied( $destnets ) && $destnets ne '-' ? $inaction || $interface ? join( ':', $interface, $destnets ) : $destnets : $inaction ? '-' : $interface,
 				 $proto,
 				 $ports,
 				 $ipsec,
@@ -5780,7 +5803,7 @@ sub process_snat1( $$$$$$$$$$$$ ) {
 	    $destnets = ALLIP unless supplied $destnets && $destnets ne '-';
 
 	    expand_rule( $chainref ,
-			 POSTROUTE_RESTRICT ,
+			 $interface ? POSTROUTE_RESTRICT : INPUT_RESTRICT ,
 			 $prerule ,
 			 $baserule . $inlinematches . $rule ,
 			 $source ,
@@ -5795,7 +5818,7 @@ sub process_snat1( $$$$$$$$$$$$ ) {
 
 	    conditional_rule_end( $chainref ) if $detectaddress || $conditional;
 
-	    if ( $add_snat_aliases && $addresses ) {
+	    if ( $interface && $add_snat_aliases && $addresses ) {
 		my ( $interface, $alias , $remainder ) = split( /:/, $fullinterface, 3 );
 		fatal_error "Invalid alias ($alias:$remainder)" if defined $remainder;
 		for my $address ( split_list $addresses, 'address' ) {

Shorewall/manpages/shorewall-snat.xml

@@ -253,10 +253,10 @@
         <listitem>
           <para>Set of hosts that you wish to masquerade. You can specify this
           as an <emphasis>address</emphasis> (net or host) or as an
-          <emphasis>interface</emphasis> (use of an
-          <emphasis>interface</emphasis> is deprecated). If you give the name
-          of an interface, the interface must be up before you start the
-          firewall and the Shorewall rules compiler will warn you of that
+          <emphasis>interface</emphasis>. Unless you want to perform SNAT in
+          the INPUT chain (see DEST below), if you give the name of an
+          interface (deprecated), the interface must be up before you start
+          the firewall and the Shorewall rules compiler will warn you of that
           fact. (Shorewall will use your main routing table to determine the
           appropriate addresses to masquerade).</para>
 
@@ -268,9 +268,9 @@
 
       <varlistentry>
         <term><emphasis role="bold">DEST</emphasis> -
-        <emphasis>interface</emphasis>[<emphasis
+        {<emphasis>interface</emphasis>[<emphasis
         role="bold">:</emphasis><emphasis>digit][,</emphasis><emphasis>interface</emphasis>[<emphasis
-        role="bold">:</emphasis><emphasis>digit</emphasis>]]...[<emphasis
+        role="bold">:</emphasis><emphasis>digit</emphasis>]]...|$FW}[<emphasis
         role="bold">:</emphasis>[<emphasis>dest-address</emphasis>[<emphasis
         role="bold">,</emphasis><emphasis>dest-address</emphasis>]...[<emphasis>exclusion</emphasis>]]</term>
 
@@ -286,6 +286,10 @@
           is the only use for the alias name; it may not appear in any other
           place in your Shorewall configuration.</emphasis></para>
 
+          <para>Beginning with Shorewall 5.1.12, SNAT may be performed in the
+          nat table's INPUT chain by specifying $FW rather than one or more
+          interfaces. </para>
+
           <para>Each interface must match an entry in <ulink
           url="/manpages/shorewall-interfaces.html">shorewall-interfaces</ulink>(5).
           Shorewall allows loose matches to wildcard entries in <ulink