meta: add l4proto support

Add support for the meta l4proto type. This is used in the inet table to
match on the transport layer protocol without requiring the network layer
protocol to be known, allowing to use transport header matches that apply
to both IPv4 and IPv6.

Signed-off-by: Patrick McHardy <kaber@trash.net>

6 files changed, 49 insertions, 0 deletions

diff --git a/include/proto.h b/include/proto.h
index 772f9ed7..bd3701e3 100644
--- a/include/proto.h
+++ b/include/proto.h
@@ -291,6 +291,7 @@ extern const struct proto_desc proto_ip;
 extern const struct proto_desc proto_ip6;
 
 extern const struct proto_desc proto_inet;
+extern const struct proto_desc proto_inet_service;
 
 extern const struct proto_desc proto_arp;
 
diff --git a/src/meta.c b/src/meta.c
index 1286569a..d7b024b6 100644
--- a/src/meta.c
+++ b/src/meta.c
@@ -303,6 +303,8 @@ static const struct meta_template meta_templates[] = {
 						2 * 8, BYTEORDER_BIG_ENDIAN),
 	[NFT_META_NFPROTO]	= META_TEMPLATE("nfproto",   &nfproto_type,
 						1 * 8, BYTEORDER_HOST_ENDIAN),
+	[NFT_META_L4PROTO]	= META_TEMPLATE("l4proto",   &inet_protocol_type,
+						1 * 8, BYTEORDER_HOST_ENDIAN),
 	[NFT_META_PRIORITY]	= META_TEMPLATE("priority",  &tchandle_type,
 						4 * 8, BYTEORDER_HOST_ENDIAN),
 	[NFT_META_MARK]		= META_TEMPLATE("mark",      &mark_type,
@@ -378,6 +380,14 @@ static void meta_expr_pctx_update(struct proto_ctx *ctx,
 
 		proto_ctx_update(ctx, PROTO_BASE_NETWORK_HDR, &expr->location, desc);
 		break;
+	case NFT_META_L4PROTO:
+		desc = proto_find_upper(&proto_inet_service,
+					mpz_get_uint8(right->value));
+		if (desc == NULL)
+			desc = &proto_unknown;
+
+		proto_ctx_update(ctx, PROTO_BASE_TRANSPORT_HDR, &expr->location, desc);
+		break;
 	default:
 		break;
 	}
@@ -408,6 +418,10 @@ struct expr *meta_expr_alloc(const struct location *loc, enum nft_meta_keys key)
 		expr->flags |= EXPR_F_PROTOCOL;
 		expr->meta.base = PROTO_BASE_LL_HDR;
 		break;
+	case NFT_META_L4PROTO:
+		expr->flags |= EXPR_F_PROTOCOL;
+		expr->meta.base = PROTO_BASE_NETWORK_HDR;
+		break;
 	default:
 		break;
 	}
diff --git a/src/parser.y b/src/parser.y
index aed00c7f..7c18875d 100644
--- a/src/parser.y
+++ b/src/parser.y
@@ -282,6 +282,7 @@ static void location_update(struct location *loc, struct location *rhs, int n)
 
 %token META			"meta"
 %token NFPROTO			"nfproto"
+%token L4PROTO			"l4proto"
 %token MARK			"mark"
 %token IIF			"iif"
 %token IIFNAME			"iifname"
@@ -1378,6 +1379,7 @@ meta_expr		:	META	meta_key
 
 meta_key		:	LENGTH		{ $$ = NFT_META_LEN; }
 			|	NFPROTO		{ $$ = NFT_META_NFPROTO; }
+			|	L4PROTO		{ $$ = NFT_META_L4PROTO; }
 			|	PROTOCOL	{ $$ = NFT_META_PROTOCOL; }
 			|	PRIORITY	{ $$ = NFT_META_PRIORITY; }
 			|	MARK		{ $$ = NFT_META_MARK; }
diff --git a/src/payload.c b/src/payload.c
index ac441d4e..a312e079 100644
--- a/src/payload.c
+++ b/src/payload.c
@@ -174,6 +174,12 @@ int payload_gen_dependency(struct eval_ctx *ctx, const struct expr *expr,
 	}
 
 	desc = ctx->pctx.protocol[expr->payload.base - 1].desc;
+	/* Special case for mixed IPv4/IPv6 tables: use meta L4 proto */
+	if (desc == NULL &&
+	    ctx->pctx.family == NFPROTO_INET &&
+	    expr->payload.base == PROTO_BASE_TRANSPORT_HDR)
+		desc = &proto_inet_service;
+
 	if (desc == NULL)
 		return expr_error(ctx, expr,
 				  "ambiguous payload specification: "
diff --git a/src/proto.c b/src/proto.c
index 81fe6cfd..56fb7930 100644
--- a/src/proto.c
+++ b/src/proto.c
@@ -626,6 +626,31 @@ const struct proto_desc proto_inet = {
 };
 
 /*
+ * Dummy protocol for cases where the network layer protocol isn't known
+ * (IPv4 or IPv6), The higher layer protocols are the protocols common to
+ * both.
+ */
+
+const struct proto_desc proto_inet_service = {
+	.name		= "inet-service",
+	.base		= PROTO_BASE_TRANSPORT_HDR,
+	.protocol_key	= 0,
+	.protocols	= {
+		PROTO_LINK(IPPROTO_ESP,		&proto_esp),
+		PROTO_LINK(IPPROTO_AH,		&proto_ah),
+		PROTO_LINK(IPPROTO_COMP,	&proto_comp),
+		PROTO_LINK(IPPROTO_UDP,		&proto_udp),
+		PROTO_LINK(IPPROTO_UDPLITE,	&proto_udplite),
+		PROTO_LINK(IPPROTO_TCP,		&proto_tcp),
+		PROTO_LINK(IPPROTO_DCCP,	&proto_dccp),
+		PROTO_LINK(IPPROTO_SCTP,	&proto_sctp),
+	},
+	.templates	= {
+		[0]	= PROTO_META_TEMPLATE("l4proto", &inet_protocol_type, NFT_META_L4PROTO, 8),
+	},
+};
+
+/*
  * ARP
  */
 
diff --git a/src/scanner.l b/src/scanner.l
index 9541eb05..0b8abacb 100644
--- a/src/scanner.l
+++ b/src/scanner.l
@@ -372,6 +372,7 @@ addrstring	({macaddr}|{ip4addr}|{ip6addr})
 
 "meta"			{ return META; }
 "nfproto"		{ return NFPROTO; }
+"l4proto"		{ return L4PROTO; }
 "mark"			{ return MARK; }
 "iif"			{ return IIF; }
 "iifname"		{ return IIFNAME; }