src: add xt compat support

At compilation time, you have to pass this option.

  # ./configure --with-xtables

And libxtables needs to be installed in your system.

This patch allows to list a ruleset containing xt extensions loaded
through iptables-compat-restore tool.

Example:

$ iptables-save > ruleset

$ cat ruleset
*filter
:INPUT ACCEPT [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -p tcp -m multiport --dports 80,81 -j REJECT
COMMIT

$ sudo iptables-compat-restore ruleset

$ sudo nft list rulseset
table ip filter {
    chain INPUT {
        type filter hook input priority 0; policy accept;
        ip protocol tcp tcp dport { 80,81} counter packets 0 bytes 0 reject
    }

    chain FORWARD {
        type filter hook forward priority 0; policy drop;
    }

    chain OUTPUT {
        type filter hook output priority 0; policy accept;
    }
}

A translation of the extension is shown if this is available. In other
case, match or target definition is preceded by a hash. For example,
classify target has not translation:

$ sudo nft list chain mangle POSTROUTING
table ip mangle {
    chain POSTROUTING {
        type filter hook postrouting priority -150; policy accept;
        ip protocol tcp tcp dport 80 counter packets 0 bytes 0 # CLASSIFY set 20:10
                                                              ^^^
    }
}

If the whole ruleset is translatable, the users can (re)load it using
"nft -f" and get nft native support for all their rules.

This patch is joint work by the authors listed below.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Signed-off-by: Pablo M. Bermudo Garay <pablombg@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 34 insertions, 0 deletions

diff --git a/include/statement.h b/include/statement.h
index e9313ca7..1b215517 100644
--- a/include/statement.h
+++ b/include/statement.h
@@ -148,6 +148,37 @@ struct flow_stmt {
 extern struct stmt *flow_stmt_alloc(const struct location *loc);
 
 /**
+ * enum nft_xt_type - xtables statement types
+ *
+ * @NFT_XT_MATCH:	match
+ * @NFT_XT_TARGET:	target
+ * @NFT_XT_WATCHER:	watcher (only for the bridge family)
+ */
+enum nft_xt_type {
+	NFT_XT_MATCH = 0,
+	NFT_XT_TARGET,
+	NFT_XT_WATCHER,
+	NFT_XT_MAX
+};
+
+struct xtables_match;
+struct xtables_target;
+
+struct xt_stmt {
+	const char			*name;
+	enum nft_xt_type		type;
+	uint32_t			proto;
+	union {
+		struct xtables_match	*match;
+		struct xtables_target	*target;
+	};
+	const char			*opts;
+	void				*entry;
+};
+
+extern struct stmt *xt_stmt_alloc(const struct location *loc);
+
+/**
  * enum stmt_types - statement types
  *
  * @STMT_INVALID:	uninitialised
@@ -168,6 +199,7 @@ extern struct stmt *flow_stmt_alloc(const struct location *loc);
  * @STMT_SET:		set statement
  * @STMT_DUP:		dup statement
  * @STMT_FWD:		forward statement
+ * @STMT_XT:		XT statement
  */
 enum stmt_types {
 	STMT_INVALID,
@@ -188,6 +220,7 @@ enum stmt_types {
 	STMT_SET,
 	STMT_DUP,
 	STMT_FWD,
+	STMT_XT,
 };
 
 /**
@@ -243,6 +276,7 @@ struct stmt {
 		struct set_stmt		set;
 		struct dup_stmt		dup;
 		struct fwd_stmt		fwd;
+		struct xt_stmt		xt;
 	};
 };