netfilter: ipset: Introduction of new commands and protocol version 7

Two new commands (IPSET_CMD_GET_BYNAME, IPSET_CMD_GET_BYINDEX) are
introduced. The new commands makes possible to eliminate the getsockopt
operation (in iptables set/SET match/target) and thus use only netlink
communication between userspace and kernel for ipset. With the new
protocol version, userspace can exactly know which functionality is
supported by the running kernel.

Both the kernel and userspace is fully backward compatible.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>

include/linux/netfilter/ipset/ip_set.h

@@ -303,11 +303,11 @@ ip_set_put_flags(struct sk_buff *skb, struct ip_set *set)
 /* Netlink CB args */
 enum {
 	IPSET_CB_NET = 0,	/* net namespace */
+	IPSET_CB_PROTO,		/* ipset protocol */
 	IPSET_CB_DUMP,		/* dump single set/all sets */
 	IPSET_CB_INDEX,		/* set index */
 	IPSET_CB_PRIVATE,	/* set private data */
 	IPSET_CB_ARG0,		/* type specific */
-	IPSET_CB_ARG1,
 };
 
 /* register and unregister set references */

include/uapi/linux/netfilter/ipset/ip_set.h

@@ -13,8 +13,9 @@
 
 #include <linux/types.h>
 
-/* The protocol version */
-#define IPSET_PROTOCOL		6
+/* The protocol versions */
+#define IPSET_PROTOCOL		7
+#define IPSET_PROTOCOL_MIN	6
 
 /* The max length of strings including NUL: set and type identifiers */
 #define IPSET_MAXNAMELEN	32
@@ -38,17 +39,19 @@ enum ipset_cmd {
 	IPSET_CMD_TEST,		/* 11: Test an element in a set */
 	IPSET_CMD_HEADER,	/* 12: Get set header data only */
 	IPSET_CMD_TYPE,		/* 13: Get set type */
+	IPSET_CMD_GET_BYNAME,	/* 14: Get set index by name */
+	IPSET_CMD_GET_BYINDEX,	/* 15: Get set name by index */
 	IPSET_MSG_MAX,		/* Netlink message commands */
 
 	/* Commands in userspace: */
-	IPSET_CMD_RESTORE = IPSET_MSG_MAX, /* 14: Enter restore mode */
-	IPSET_CMD_HELP,		/* 15: Get help */
-	IPSET_CMD_VERSION,	/* 16: Get program version */
-	IPSET_CMD_QUIT,		/* 17: Quit from interactive mode */
+	IPSET_CMD_RESTORE = IPSET_MSG_MAX, /* 16: Enter restore mode */
+	IPSET_CMD_HELP,		/* 17: Get help */
+	IPSET_CMD_VERSION,	/* 18: Get program version */
+	IPSET_CMD_QUIT,		/* 19: Quit from interactive mode */
 
 	IPSET_CMD_MAX,
 
-	IPSET_CMD_COMMIT = IPSET_CMD_MAX, /* 18: Commit buffered commands */
+	IPSET_CMD_COMMIT = IPSET_CMD_MAX, /* 20: Commit buffered commands */
 };
 
 /* Attributes at command level */
@@ -66,6 +69,7 @@ enum {
 	IPSET_ATTR_LINENO,	/* 9: Restore lineno */
 	IPSET_ATTR_PROTOCOL_MIN, /* 10: Minimal supported version number */
 	IPSET_ATTR_REVISION_MIN	= IPSET_ATTR_PROTOCOL_MIN, /* type rev min */
+	IPSET_ATTR_INDEX,	/* 11: Kernel index of set */
 	__IPSET_ATTR_CMD_MAX,
 };
 #define IPSET_ATTR_CMD_MAX	(__IPSET_ATTR_CMD_MAX - 1)
@@ -223,6 +227,7 @@ enum ipset_adt {
 
 /* Sets are identified by an index in kernel space. Tweak with ip_set_id_t
  * and IPSET_INVALID_ID if you want to increase the max number of sets.
+ * Also, IPSET_ATTR_INDEX must be changed.
  */
 typedef __u16 ip_set_id_t;