ct: add support for setting ct mark

This patch adds the possibility to set ct keys using nft. Currently, the
connection mark is supported. This functionality enables creating rules
performing the same action as iptables -j CONNMARK --save-mark. For example:

table ip filter {
	chain postrouting {
		type filter hook postrouting priority 0;
		ip protocol icmp ip daddr 8.8.8.8 ct mark set meta mark
	}
}

My patch is based on the original http://patchwork.ozlabs.org/patch/307677/
by Kristian Evensen <kristian.evensen@gmail.com>.

I simply did a rebase and some testing. To test, I added rules like these:
 counter meta mark set 1 counter
 counter ct mark set mark counter
 counter ct mark 1 counter

The last matching worked as expected, which means the second rule is also
working as expected.

Signed-off-by: Arturo Borrero Gonzalez <arturo.borrero.glez@gmail.com>
Acked-by: Kristian Evensen <kristian.evensen@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

5 files changed, 98 insertions, 3 deletions

diff --git a/src/ct.c b/src/ct.c
index a27621e2..30639b24 100644
--- a/src/ct.c
+++ b/src/ct.c
@@ -27,6 +27,7 @@
 #include <ct.h>
 #include <gmputil.h>
 #include <utils.h>
+#include <statement.h>
 
 static const struct symbol_table ct_state_tbl = {
 	.symbols	= {
@@ -290,6 +291,30 @@ void ct_expr_update_type(struct proto_ctx *ctx, struct expr *expr)
 	}
 }
 
+static void ct_stmt_print(const struct stmt *stmt)
+{
+	printf("ct %s set ", ct_templates[stmt->ct.key].token);
+	expr_print(stmt->ct.expr);
+}
+
+static const struct stmt_ops ct_stmt_ops = {
+	.type		= STMT_CT,
+	.name		= "ct",
+	.print		= ct_stmt_print,
+};
+
+struct stmt *ct_stmt_alloc(const struct location *loc, enum nft_ct_keys key,
+			     struct expr *expr)
+{
+	struct stmt *stmt;
+
+	stmt = stmt_alloc(loc, &ct_stmt_ops);
+	stmt->ct.key	= key;
+	stmt->ct.tmpl	= &ct_templates[key];
+	stmt->ct.expr	= expr;
+	return stmt;
+}
+
 static void __init ct_init(void)
 {
 	datatype_register(&ct_state_type);
diff --git a/src/evaluate.c b/src/evaluate.c
index fff8fef1..dc4406cd 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1170,6 +1170,15 @@ static int stmt_evaluate_nat(struct eval_ctx *ctx, struct stmt *stmt)
 	return 0;
 }
 
+static int stmt_evaluate_ct(struct eval_ctx *ctx, struct stmt *stmt)
+{
+	expr_set_context(&ctx->ectx, stmt->ct.tmpl->dtype,
+			 stmt->ct.tmpl->len);
+	if (expr_evaluate(ctx, &stmt->ct.expr) < 0)
+		return -1;
+	return 0;
+}
+
 static int stmt_evaluate(struct eval_ctx *ctx, struct stmt *stmt)
 {
 #ifdef DEBUG
@@ -1197,6 +1206,8 @@ static int stmt_evaluate(struct eval_ctx *ctx, struct stmt *stmt)
 		return stmt_evaluate_nat(ctx, stmt);
 	case STMT_QUEUE:
 		return 0;
+	case STMT_CT:
+		return stmt_evaluate_ct(ctx, stmt);
 	default:
 		BUG("unknown statement type %s\n", stmt->ops->name);
 	}
diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c
index ca720913..62cbf0e4 100644
--- a/src/netlink_delinearize.c
+++ b/src/netlink_delinearize.c
@@ -365,9 +365,27 @@ static void netlink_parse_meta(struct netlink_parse_ctx *ctx,
 		netlink_parse_meta_sreg(ctx, loc, nle);
 }
 
-static void netlink_parse_ct(struct netlink_parse_ctx *ctx,
-			     const struct location *loc,
-			     const struct nft_rule_expr *nle)
+static void netlink_parse_ct_sreg(struct netlink_parse_ctx *ctx,
+				  const struct location *loc,
+				  const struct nft_rule_expr *nle)
+{
+	struct stmt *stmt;
+	struct expr *expr;
+
+	expr = netlink_get_register(ctx, loc,
+				    nft_rule_expr_get_u32(nle,
+							  NFT_EXPR_CT_SREG));
+	stmt = ct_stmt_alloc(loc,
+			     nft_rule_expr_get_u32(nle, NFT_EXPR_CT_KEY),
+			     expr);
+	expr_set_type(expr, stmt->ct.tmpl->dtype, stmt->ct.tmpl->byteorder);
+
+	list_add_tail(&stmt->list, &ctx->rule->stmts);
+}
+
+static void netlink_parse_ct_dreg(struct netlink_parse_ctx *ctx,
+				  const struct location *loc,
+				  const struct nft_rule_expr *nle)
 {
 	struct expr *expr;
 
@@ -377,6 +395,16 @@ static void netlink_parse_ct(struct netlink_parse_ctx *ctx,
 			     expr);
 }
 
+static void netlink_parse_ct(struct netlink_parse_ctx *ctx,
+			     const struct location *loc,
+			     const struct nft_rule_expr *nle)
+{
+	if (nft_rule_expr_is_set(nle, NFT_EXPR_CT_DREG))
+		netlink_parse_ct_dreg(ctx, loc, nle);
+	else
+		netlink_parse_ct_sreg(ctx, loc, nle);
+}
+
 static void netlink_parse_counter(struct netlink_parse_ctx *ctx,
 				  const struct location *loc,
 				  const struct nft_rule_expr *nle)
@@ -858,6 +886,10 @@ static void rule_parse_postprocess(struct netlink_parse_ctx *ctx, struct rule *r
 			if (stmt->meta.expr != NULL)
 				expr_postprocess(&rctx, stmt, &stmt->meta.expr);
 			break;
+		case STMT_CT:
+			if (stmt->ct.expr != NULL)
+				expr_postprocess(&rctx, stmt, &stmt->ct.expr);
+			break;
 		case STMT_NAT:
 			if (stmt->nat.addr != NULL)
 				expr_postprocess(&rctx, stmt, &stmt->nat.addr);
diff --git a/src/netlink_linearize.c b/src/netlink_linearize.c
index 9d59374c..e80646b6 100644
--- a/src/netlink_linearize.c
+++ b/src/netlink_linearize.c
@@ -662,6 +662,22 @@ static void netlink_gen_queue_stmt(struct netlink_linearize_ctx *ctx,
 	nft_rule_add_expr(ctx->nlr, nle);
 }
 
+static void netlink_gen_ct_stmt(struct netlink_linearize_ctx *ctx,
+				  const struct stmt *stmt)
+{
+	struct nft_rule_expr *nle;
+	enum nft_registers sreg;
+
+	sreg = get_register(ctx);
+	netlink_gen_expr(ctx, stmt->ct.expr, sreg);
+	release_register(ctx);
+
+	nle = alloc_nft_expr("ct");
+	nft_rule_expr_set_u32(nle, NFT_EXPR_CT_SREG, sreg);
+	nft_rule_expr_set_u32(nle, NFT_EXPR_CT_KEY, stmt->ct.key);
+	nft_rule_add_expr(ctx->nlr, nle);
+}
+
 static void netlink_gen_stmt(struct netlink_linearize_ctx *ctx,
 			     const struct stmt *stmt)
 {
@@ -684,6 +700,8 @@ static void netlink_gen_stmt(struct netlink_linearize_ctx *ctx,
 		return netlink_gen_nat_stmt(ctx, stmt);
 	case STMT_QUEUE:
 		return netlink_gen_queue_stmt(ctx, stmt);
+	case STMT_CT:
+		return netlink_gen_ct_stmt(ctx, stmt);
 	default:
 		BUG("unknown statement type %s\n", stmt->ops->name);
 	}
diff --git a/src/parser.y b/src/parser.y
index 0d97ae98..db6f4933 100644
--- a/src/parser.y
+++ b/src/parser.y
@@ -392,6 +392,8 @@ static void location_update(struct location *loc, struct location *rhs, int n)
 %destructor { stmt_free($$); }	stmt match_stmt verdict_stmt
 %type <stmt>			counter_stmt counter_stmt_alloc
 %destructor { stmt_free($$); }	counter_stmt counter_stmt_alloc
+%type <stmt>			ct_stmt
+%destructor { stmt_free($$); }	ct_stmt
 %type <stmt>			meta_stmt
 %destructor { stmt_free($$); }	meta_stmt
 %type <stmt>			log_stmt log_stmt_alloc
@@ -1069,6 +1071,7 @@ stmt			:	verdict_stmt
 			|	reject_stmt
 			|	nat_stmt
 			|	queue_stmt
+			|	ct_stmt
 			;
 
 verdict_stmt		:	verdict_expr
@@ -1593,6 +1596,12 @@ ct_key			:	STATE		{ $$ = NFT_CT_STATE; }
 			|	LABEL		{ $$ = NFT_CT_LABEL; }
 			;
 
+ct_stmt			:	CT	ct_key		SET	expr
+			{
+				$$ = ct_stmt_alloc(&@$, $2, $4);
+			}
+			;
+
 payload_expr		:	payload_raw_expr
 			|	eth_hdr_expr
 			|	vlan_hdr_expr