src: Add support for pkttype in meta expresion

If you want to match the pkttype field of the skbuff, you have to
use the following syntax:

 nft add rule ip filter input meta pkttype PACKET_TYPE

where PACKET_TYPE can be: unicast, broadcast and multicast.

Joint work with Alvaro Neira Ayuso <alvaroneay@gmail.com>

Signed-off-by: Alvaro Neira Ayuso <alvaroneay@gmail.com>
Signed-off-by: Ana Rey <anarey@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

3 files changed, 58 insertions, 0 deletions

diff --git a/src/meta.c b/src/meta.c
index 80f88ffb..7b75caf7 100644
--- a/src/meta.c
+++ b/src/meta.c
@@ -20,6 +20,7 @@
 #include <pwd.h>
 #include <grp.h>
 #include <linux/pkt_sched.h>
+#include <linux/if_packet.h>
 
 #include <nftables.h>
 #include <expression.h>
@@ -297,6 +298,57 @@ static const struct datatype gid_type = {
 	.parse		= gid_type_parse,
 };
 
+static const struct symbol_table pkttype_type_tbl = {
+	.symbols	= {
+		SYMBOL("unicast", PACKET_HOST),
+		SYMBOL("broadcast", PACKET_BROADCAST),
+		SYMBOL("multicast", PACKET_MULTICAST),
+		SYMBOL_LIST_END,
+	},
+};
+
+static void pkttype_type_print(const struct expr *expr)
+{
+	return symbolic_constant_print(&pkttype_type_tbl, expr);
+}
+
+static struct error_record *pkttype_type_parse(const struct expr *sym,
+					       struct expr **res)
+{
+	struct error_record *erec;
+	const struct symbolic_constant *s;
+
+	for (s = pkttype_type_tbl.symbols; s->identifier != NULL; s++) {
+		if (!strcmp(sym->identifier, s->identifier)) {
+			*res = constant_expr_alloc(&sym->location, sym->dtype,
+						   sym->dtype->byteorder,
+						   sym->dtype->size,
+						   &s->value);
+			return NULL;
+		}
+	}
+
+	*res = NULL;
+	erec = sym->dtype->basetype->parse(sym, res);
+	if (erec != NULL)
+		return erec;
+	if (*res)
+		return NULL;
+
+	return symbolic_constant_parse(sym, &pkttype_type_tbl, res);
+}
+
+static const struct datatype pkttype_type = {
+	.type		= TYPE_PKTTYPE,
+	.name		= "pkt_type",
+	.desc		= "packet type",
+	.byteorder	= BYTEORDER_HOST_ENDIAN,
+	.size		= BITS_PER_BYTE,
+	.basetype	= &integer_type,
+	.print		= pkttype_type_print,
+	.parse		= pkttype_type_parse,
+};
+
 static const struct meta_template meta_templates[] = {
 	[NFT_META_LEN]		= META_TEMPLATE("length",    &integer_type,
 						4 * 8, BYTEORDER_HOST_ENDIAN),
@@ -338,6 +390,9 @@ static const struct meta_template meta_templates[] = {
 	[NFT_META_BRI_OIFNAME]	= META_TEMPLATE("obriport",  &string_type,
 						IFNAMSIZ * BITS_PER_BYTE,
 						BYTEORDER_HOST_ENDIAN),
+	[NFT_META_PKTTYPE]	= META_TEMPLATE("pkttype",  &pkttype_type,
+						BITS_PER_BYTE,
+						BYTEORDER_HOST_ENDIAN),
 };
 
 static void meta_expr_print(const struct expr *expr)
diff --git a/src/parser.y b/src/parser.y
index 26d28793..f06a2651 100644
--- a/src/parser.y
+++ b/src/parser.y
@@ -325,6 +325,7 @@ static int monitor_lookup_event(const char *event)
 %token RTCLASSID		"rtclassid"
 %token IBRIPORT			"ibriport"
 %token OBRIPORT			"obriport"
+%token PKTTYPE			"pkttype"
 
 %token CT			"ct"
 %token DIRECTION		"direction"
@@ -1838,6 +1839,7 @@ meta_key_unqualified	:	MARK		{ $$ = NFT_META_MARK; }
 			|	RTCLASSID	{ $$ = NFT_META_RTCLASSID; }
 			|	IBRIPORT	{ $$ = NFT_META_BRI_IIFNAME; }
 			|       OBRIPORT	{ $$ = NFT_META_BRI_OIFNAME; }
+			|       PKTTYPE		{ $$ = NFT_META_PKTTYPE; }
 			;
 
 meta_stmt		:	META	meta_key	SET	expr
diff --git a/src/scanner.l b/src/scanner.l
index 4eec92f5..ca6db6e1 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -415,6 +415,7 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 "rtclassid"		{ return RTCLASSID; }
 "ibriport"		{ return IBRIPORT; }
 "obriport"		{ return OBRIPORT; }
+"pkttype"		{ return PKTTYPE; }
 
 "ct"			{ return CT; }
 "direction"		{ return DIRECTION; }