Add bpf_lua_type function

Author: VictorNogueiraRio

include/uapi/linux/bpf.h

@@ -2976,6 +2976,20 @@ union bpf_attr {
  *	Return
  *		1 if the value at the given index of the Lua stack is a
  *		string; otherwise it returns 0
+ *
+ * void bpf_lua_type(void *ctx, int index)
+ *	Description
+ *		Obtains the type of the Lua value at the given index
+ *		of the Lua stack
+ *
+ *	Return
+ *		Type of the value in the given valid index,
+ *		or LUA_TNONE for a non-valid (but acceptable) index.
+ *		The types returned by lua_type are coded by the
+ *		following constants defined in lua.h: LUA_TNIL (0),
+ *		LUA_TNUMBER, LUA_TBOOLEAN, LUA_TSTRING, LUA_TTABLE,
+ *		LUA_TFUNCTION, LUA_TUSERDATA, LUA_TTHREAD, and
+ *		LUA_TLIGHTUSERDATA.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -3111,7 +3125,8 @@ union bpf_attr {
 	FN(lua_toboolean),		\
 	FN(lua_tointeger),		\
 	FN(lua_newpacket),		\
-	FN(lua_tostring),
+	FN(lua_tostring),		\
+	FN(lua_type),
 	/* #endif CONFIG_XDP_LUA */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper

net/core/filter.c

@@ -6112,6 +6112,19 @@ static const struct bpf_func_proto bpf_lua_tostring_proto = {
 	.arg3_type	= ARG_CONST_SIZE,
 	.arg4_type	= ARG_ANYTHING,
 };
+
+BPF_CALL_2(bpf_lua_type, struct xdp_buff *, ctx, int, index) {
+       return lua_type(ctx->L, index);
+}
+
+static const struct bpf_func_proto bpf_lua_type_proto = {
+       .func           = bpf_lua_type,
+       .gpl_only       = false,
+       .pkt_access     = false,
+       .ret_type       = RET_INTEGER,
+       .arg1_type      = ARG_PTR_TO_CTX,
+       .arg2_type      = ARG_ANYTHING,
+};
 #endif /* CONFIG_XDP_LUA */
 
 bool bpf_helper_changes_pkt_data(void *func)
@@ -6219,6 +6232,8 @@ bpf_base_func_proto(enum bpf_func_id func_id)
 		return &bpf_lua_newpacket_proto;
 	case BPF_FUNC_lua_tostring:
 		return &bpf_lua_tostring_proto;
+	case BPF_FUNC_lua_type:
+		return &bpf_lua_type_proto;
 #endif /* CONFIG_XDP_LUA */
 	default:
 		return NULL;

tools/include/uapi/linux/bpf.h

@@ -2981,6 +2981,20 @@ union bpf_attr {
  *	Return
  *		1 if the value at the given index of the Lua stack is a
  *		string; otherwise it returns 0
+ *
+ * void bpf_lua_type(void *ctx, int index)
+ *	Description
+ *		Obtains the type of the Lua value at the given index
+ *		of the Lua stack
+ *
+ *	Return
+ *		Type of the value in the given valid index,
+ *		or LUA_TNONE for a non-valid (but acceptable) index.
+ *		The types returned by lua_type are coded by the
+ *		following constants defined in lua.h: LUA_TNIL (0),
+ *		LUA_TNUMBER, LUA_TBOOLEAN, LUA_TSTRING, LUA_TTABLE,
+ *		LUA_TFUNCTION, LUA_TUSERDATA, LUA_TTHREAD, and
+ *		LUA_TLIGHTUSERDATA.
  */
 #define __BPF_FUNC_MAPPER(FN)		\
 	FN(unspec),			\
@@ -3116,7 +3130,8 @@ union bpf_attr {
 	FN(lua_toboolean),		\
 	FN(lua_tointeger),		\
 	FN(lua_newpacket),		\
-	FN(lua_tostring),
+	FN(lua_tostring),		\
+	FN(lua_type),
 	/* #endif CONFIG_XDP_LUA */
 
 /* integer value in 'imm' field of BPF_CALL instruction selects which helper