Introduce a new feature in IPFW: Check of the source or destination

address is configured on a interface.  This is useful for routers with
dynamic interfaces.  It is now possible to say:

        0100 allow       tcp from any to any established
        0200 skipto 1000 tcp from any to any
        0300 allow       ip from any to any
        1000 allow       tcp from 1.2.3.4 to me 22
        1010 deny        tcp from any to me 22
        1020 allow       tcp from any to any

and not have to worry about the behaviour if dynamic interfaces configure
new IP numbers later on.

The check is semi expensive (traverses the interface address list)
so it should be protected as in the above example if high performance
is a requirement.

4 files changed, 89 insertions, 41 deletions

diff --git a/sbin/ipfw/ipfw.8 b/sbin/ipfw/ipfw.8
index 765fb3d..a64f290 100644
--- a/sbin/ipfw/ipfw.8
+++ b/sbin/ipfw/ipfw.8
@@ -478,9 +478,23 @@ or
 .Cm all
 keywords mean any protocol will match.
 .It Ar src No and Ar dst :
+.Cm any
+|
+.Cm me
+|
+.Op Cm not
 .Aq Ar address Ns / Ns Ar mask
 .Op Ar ports
 .Pp
+Specifying
+.Cm any
+makes the rule match any IP number.
+.Pp
+Specifying
+.Cm me
+makes the rule match any IP number configured on an interface in the system.
+This is an computationally semi-expensive check which should be used with care.
+.Pp
 The
 .Aq Ar address Ns / Ns Ar mask
 may be specified as:
diff --git a/sbin/ipfw/ipfw.c b/sbin/ipfw/ipfw.c
index d8f4934..247b7a5 100644
--- a/sbin/ipfw/ipfw.c
+++ b/sbin/ipfw/ipfw.c
@@ -276,17 +276,20 @@ show_ipfw(struct ip_fw *chain, int pcwidth, int bcwidth)
 	else
 		printf(" %u", chain->fw_prot);
 
-	printf(" from %s", chain->fw_flg & IP_FW_F_INVSRC ? "not " : "");
-
-	adrt=ntohl(chain->fw_smsk.s_addr);
-	if (adrt==ULONG_MAX && do_resolv) {
-		adrt=(chain->fw_src.s_addr);
-		he=gethostbyaddr((char *)&adrt,sizeof(u_long),AF_INET);
-		if (he==NULL) {
-			printf(inet_ntoa(chain->fw_src));
-		} else
-			printf("%s",he->h_name);
-	} else {
+	if (chain->fw_flg & IP_FW_F_SME) {
+		printf(" from me");
+	} else {		
+		printf(" from %s", chain->fw_flg & IP_FW_F_INVSRC ? "not " : "");
+
+		adrt=ntohl(chain->fw_smsk.s_addr);
+		if (adrt==ULONG_MAX && do_resolv) {
+			adrt=(chain->fw_src.s_addr);
+			he=gethostbyaddr((char *)&adrt,sizeof(u_long),AF_INET);
+			if (he==NULL) {
+				printf(inet_ntoa(chain->fw_src));
+			} else
+				printf("%s",he->h_name);
+		} else {
 		if (adrt!=ULONG_MAX) {
 			mb=mask_bits(chain->fw_smsk);
 			if (mb == 0) {
@@ -303,6 +306,7 @@ show_ipfw(struct ip_fw *chain, int pcwidth, int bcwidth)
 			}
 		} else
 			printf(inet_ntoa(chain->fw_src));
+		}
 	}
 
 	if (chain->fw_prot == IPPROTO_TCP || chain->fw_prot == IPPROTO_UDP) {
@@ -318,33 +322,37 @@ show_ipfw(struct ip_fw *chain, int pcwidth, int bcwidth)
 		}
 	}
 
-	printf(" to %s", chain->fw_flg & IP_FW_F_INVDST ? "not " : "");
-
-	adrt=ntohl(chain->fw_dmsk.s_addr);
-	if (adrt==ULONG_MAX && do_resolv) {
-		adrt=(chain->fw_dst.s_addr);
-		he=gethostbyaddr((char *)&adrt,sizeof(u_long),AF_INET);
-		if (he==NULL) {
-			printf(inet_ntoa(chain->fw_dst));
-		} else
-			printf("%s",he->h_name);
-	} else {
-		if (adrt!=ULONG_MAX) {
-			mb=mask_bits(chain->fw_dmsk);
-			if (mb == 0) {
-				printf("any");
-			} else {
-				if (mb > 0) {
-					printf(inet_ntoa(chain->fw_dst));
-					printf("/%d",mb);
+	if (chain->fw_flg & IP_FW_F_DME) {
+		printf(" to me");
+	} else {		
+		printf(" to %s", chain->fw_flg & IP_FW_F_INVDST ? "not " : "");
+
+		adrt=ntohl(chain->fw_dmsk.s_addr);
+		if (adrt==ULONG_MAX && do_resolv) {
+			adrt=(chain->fw_dst.s_addr);
+			he=gethostbyaddr((char *)&adrt,sizeof(u_long),AF_INET);
+			if (he==NULL) {
+				printf(inet_ntoa(chain->fw_dst));
+			} else
+				printf("%s",he->h_name);
+		} else {
+			if (adrt!=ULONG_MAX) {
+				mb=mask_bits(chain->fw_dmsk);
+				if (mb == 0) {
+					printf("any");
 				} else {
-					printf(inet_ntoa(chain->fw_dst));
-					printf(":");
-					printf(inet_ntoa(chain->fw_dmsk));
+					if (mb > 0) {
+						printf(inet_ntoa(chain->fw_dst));
+						printf("/%d",mb);
+					} else {
+						printf(inet_ntoa(chain->fw_dst));
+						printf(":");
+						printf(inet_ntoa(chain->fw_dmsk));
+					}
 				}
-			}
-		} else
-			printf(inet_ntoa(chain->fw_dst));
+			} else
+				printf(inet_ntoa(chain->fw_dst));
+		}
 	}
 
 	if (chain->fw_prot == IPPROTO_TCP || chain->fw_prot == IPPROTO_UDP) {
@@ -857,8 +865,8 @@ show_usage(const char *fmt, ...)
 "       reset|count|skipto num|divert port|tee port|fwd ip|\n"
 "       pipe num} [log [logamount count]]\n"
 "    proto: {ip|tcp|udp|icmp|<number>}\n"
-"    src: from [not] {any|ip[{/bits|:mask}]} [{port|port-port},[port],...]\n"
-"    dst: to [not] {any|ip[{/bits|:mask}]} [{port|port-port},[port],...]\n"
+"    src: from [not] {me|any|ip[{/bits|:mask}]} [{port|port-port},[port],...]\n"
+"    dst: to [not] {me|any|ip[{/bits|:mask}]} [{port|port-port},[port],...]\n"
 "  extras:\n"
 "    uid {user id}\n"
 "    gid {group id}\n"
@@ -1792,7 +1800,12 @@ add(ac,av)
 	if (!ac)
 		show_usage("missing arguments");
 
-	fill_ip(&rule.fw_src, &rule.fw_smsk, &ac, &av);
+	if (ac && !strncmp(*av,"me",strlen(*av))) {
+		rule.fw_flg |= IP_FW_F_SME;
+		av++; ac--;
+	} else {
+		fill_ip(&rule.fw_src, &rule.fw_smsk, &ac, &av);
+	}
 
 	if (ac && (isdigit(**av) || lookup_port(*av, rule.fw_prot, 1, 1) >= 0)) {
 		u_short nports = 0;
@@ -1819,7 +1832,13 @@ add(ac,av)
 	if (!ac)
 		show_usage("missing arguments");
 
-	fill_ip(&rule.fw_dst, &rule.fw_dmsk, &ac, &av);
+	
+	if (ac && !strncmp(*av,"me",strlen(*av))) {
+		rule.fw_flg |= IP_FW_F_DME;
+		av++; ac--;
+	} else {
+		fill_ip(&rule.fw_dst, &rule.fw_dmsk, &ac, &av);
+	}
 
 	if (ac && (isdigit(**av) || lookup_port(*av, rule.fw_prot, 1, 1) >= 0)) {
 		u_short	nports = 0;
diff --git a/sys/netinet/ip_fw.c b/sys/netinet/ip_fw.c
index 66dc6f1..8a53b1f 100644
--- a/sys/netinet/ip_fw.c
+++ b/sys/netinet/ip_fw.c
@@ -47,6 +47,7 @@
 #include <net/route.h>
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
+#include <netinet/in_var.h>
 #include <netinet/in_pcb.h>
 #include <netinet/ip.h>
 #include <netinet/ip_var.h>
@@ -947,6 +948,7 @@ ip_fw_chk(struct ip **pip, int hlen,
 	struct ip_fw *f = NULL, *rule = NULL;
 	struct ip *ip = *pip;
 	struct ifnet *const rif = (*m)->m_pkthdr.rcvif;
+	struct ifnet *tif;
 	u_short offset = 0 ;
 	u_short src_port = 0, dst_port = 0;
 	struct in_addr src_ip, dst_ip; /* XXX */
@@ -1111,6 +1113,16 @@ again:
 		if ((f->fw_flg & IP_FW_F_FRAG) && offset == 0 )
 			continue;
 
+		if (f->fw_flg & IP_FW_F_SME) {
+			INADDR_TO_IFP(src_ip, tif);
+			if (tif == NULL)
+				continue;
+		}
+		if (f->fw_flg & IP_FW_F_DME) {
+			INADDR_TO_IFP(dst_ip, tif);
+			if (tif == NULL)
+				continue;
+		}
 		/* If src-addr doesn't match, not this rule. */
 		if (((f->fw_flg & IP_FW_F_INVSRC) != 0) ^ ((src_ip.s_addr
 		    & f->fw_smsk.s_addr) != f->fw_src.s_addr))
diff --git a/sys/netinet/ip_fw.h b/sys/netinet/ip_fw.h
index 81da17a..7abae15 100644
--- a/sys/netinet/ip_fw.h
+++ b/sys/netinet/ip_fw.h
@@ -212,7 +212,10 @@ struct ipfw_dyn_rule {
 #define IP_FW_F_KEEP_S	0x08000000	/* keep state	 			*/
 #define IP_FW_F_CHECK_S	0x10000000	/* check state	 			*/
 
-#define IP_FW_F_MASK	0x1FFFFFFF	/* All possible flag bits mask		*/
+#define IP_FW_F_SME	0x20000000	/* source = me				*/
+#define IP_FW_F_DME	0x40000000	/* destination = me			*/
+
+#define IP_FW_F_MASK	0x7FFFFFFF	/* All possible flag bits mask		*/
 
 /* 
  * Flags for the 'fw_ipflg' field, for comparing values of ip and its protocols.