src: support of dynamic map addition and update of elements

The support of dynamic adds and updates are only available for sets
and meters. This patch gives such abilities to maps as well.

This patch is useful in cases where dynamic population of maps are
required, for example, to maintain a persistence during some period
of time.

Example:

table ip nftlb {
    map persistencia {
        type ipv4_addr : mark
        timeout 1h
        elements = { 192.168.1.132 expires 59m55s : 0x00000064,
                     192.168.56.101 expires 59m24s : 0x00000065 }
    }

    chain pre {
        type nat hook prerouting priority 0; policy accept;
        map update \
            { @nh,96,32 : numgen inc mod 2 offset 100 } @persistencia
    }
}

An example of the netlink generated sequence:

 nft --debug=netlink add rule ip nftlb pre map add \
    { ip saddr : numgen inc mod 2 offset 100 } @persistencia
ip nftlb pre
  [ payload load 4b @ network header + 12 => reg 1 ]
  [ numgen reg 2 = inc mod 2 offset 100 ]
  [ dynset add reg_key 1 set persistencia sreg_data 2 ]

Signed-off-by: Laura Garcia Liebana <nevola@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

6 files changed, 102 insertions, 2 deletions

diff --git a/include/statement.h b/include/statement.h
index 27c73567..bb4af9d3 100644
--- a/include/statement.h
+++ b/include/statement.h
@@ -171,6 +171,14 @@ struct set_stmt {
 
 extern struct stmt *set_stmt_alloc(const struct location *loc);
 
+struct map_stmt {
+	struct expr		*set;
+	struct expr		*map;
+	enum nft_dynset_ops	op;
+};
+
+extern struct stmt *map_stmt_alloc(const struct location *loc);
+
 struct meter_stmt {
 	struct expr		*set;
 	struct expr		*key;
@@ -238,6 +246,7 @@ extern struct stmt *xt_stmt_alloc(const struct location *loc);
  * @STMT_OBJREF:	stateful object reference statement
  * @STMT_EXTHDR:	extension header statement
  * @STMT_FLOW_OFFLOAD:	flow offload statement
+ * @STMT_MAP:		map statement
  */
 enum stmt_types {
 	STMT_INVALID,
@@ -264,6 +273,7 @@ enum stmt_types {
 	STMT_OBJREF,
 	STMT_EXTHDR,
 	STMT_FLOW_OFFLOAD,
+	STMT_MAP,
 };
 
 /**
@@ -325,6 +335,7 @@ struct stmt {
 		struct xt_stmt		xt;
 		struct objref_stmt	objref;
 		struct flow_stmt	flow;
+		struct map_stmt		map;
 	};
 };
 
diff --git a/src/evaluate.c b/src/evaluate.c
index a2c1c728..b71b67b9 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -2681,6 +2681,14 @@ static int stmt_evaluate_set(struct eval_ctx *ctx, struct stmt *stmt)
 	return 0;
 }
 
+static int stmt_evaluate_map(struct eval_ctx *ctx, struct stmt *stmt)
+{
+	if (expr_evaluate(ctx, &stmt->map.map->map) < 0)
+		return -1;
+
+	return 0;
+}
+
 static int stmt_evaluate_objref_map(struct eval_ctx *ctx, struct stmt *stmt)
 {
 	struct expr *map = stmt->objref.expr;
@@ -2822,6 +2830,8 @@ int stmt_evaluate(struct eval_ctx *ctx, struct stmt *stmt)
 		return stmt_evaluate_set(ctx, stmt);
 	case STMT_OBJREF:
 		return stmt_evaluate_objref(ctx, stmt);
+	case STMT_MAP:
+		return stmt_evaluate_map(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 d65aacf8..d225b3e4 100644
--- a/src/netlink_delinearize.c
+++ b/src/netlink_delinearize.c
@@ -1150,11 +1150,11 @@ static void netlink_parse_dynset(struct netlink_parse_ctx *ctx,
 				 const struct location *loc,
 				 const struct nftnl_expr *nle)
 {
+	struct expr *expr, *expr_data = NULL;
+	enum nft_registers sreg, sreg_data;
 	const struct nftnl_expr *dnle;
-	struct expr *expr;
 	struct stmt *stmt, *dstmt;
 	struct set *set;
-	enum nft_registers sreg;
 	const char *name;
 
 	name = nftnl_expr_get_str(nle, NFTNL_EXPR_DYNSET_SET_NAME);
@@ -1191,11 +1191,21 @@ static void netlink_parse_dynset(struct netlink_parse_ctx *ctx,
 		dstmt = ctx->stmt;
 	}
 
+	if (nftnl_expr_is_set(nle, NFTNL_EXPR_DYNSET_SREG_DATA)) {
+		sreg_data = netlink_parse_register(nle, NFTNL_EXPR_DYNSET_SREG_DATA);
+		expr_data = netlink_get_register(ctx, loc, sreg_data);
+	}
+
 	if (dstmt != NULL) {
 		stmt = meter_stmt_alloc(loc);
 		stmt->meter.set  = set_ref_expr_alloc(loc, set);
 		stmt->meter.key  = expr;
 		stmt->meter.stmt = dstmt;
+	} else if (expr_data != NULL) {
+		stmt = map_stmt_alloc(loc);
+		stmt->map.set	= set_ref_expr_alloc(loc, set);
+		stmt->map.map	= map_expr_alloc(loc, expr, expr_data);
+		stmt->map.op	= nftnl_expr_get_u32(nle, NFTNL_EXPR_DYNSET_OP);
 	} else {
 		stmt = set_stmt_alloc(loc);
 		stmt->set.set   = set_ref_expr_alloc(loc, set);
diff --git a/src/netlink_linearize.c b/src/netlink_linearize.c
index 5edb2d3d..be1c750c 100644
--- a/src/netlink_linearize.c
+++ b/src/netlink_linearize.c
@@ -1234,6 +1234,33 @@ static void netlink_gen_set_stmt(struct netlink_linearize_ctx *ctx,
 	nftnl_rule_add_expr(ctx->nlr, nle);
 }
 
+static void netlink_gen_map_stmt(struct netlink_linearize_ctx *ctx,
+				 const struct stmt *stmt)
+{
+	struct nftnl_expr *nle;
+	enum nft_registers sreg_key;
+	enum nft_registers sreg_data;
+
+	sreg_key = get_register(ctx, stmt->map.map->map->key);
+	netlink_gen_expr(ctx, stmt->map.map->map->key, sreg_key);
+
+	sreg_data = get_register(ctx, stmt->map.map->mappings);
+	netlink_gen_expr(ctx, stmt->map.map->mappings, sreg_data);
+
+	release_register(ctx, stmt->map.map->map->key);
+	release_register(ctx, stmt->map.map->mappings);
+
+	nle = alloc_nft_expr("dynset");
+	netlink_put_register(nle, NFTNL_EXPR_DYNSET_SREG_KEY, sreg_key);
+	netlink_put_register(nle, NFTNL_EXPR_DYNSET_SREG_DATA, sreg_data);
+
+	nftnl_expr_set_u32(nle, NFTNL_EXPR_DYNSET_OP, stmt->map.op);
+	nftnl_expr_set_str(nle, NFTNL_EXPR_DYNSET_SET_NAME, stmt->map.set->identifier);
+	nftnl_expr_set_u32(nle, NFTNL_EXPR_DYNSET_SET_ID, stmt->map.set->set->handle.set_id);
+
+	nftnl_rule_add_expr(ctx->nlr, nle);
+}
+
 static void netlink_gen_meter_stmt(struct netlink_linearize_ctx *ctx,
 				   const struct stmt *stmt)
 {
@@ -1315,6 +1342,8 @@ static void netlink_gen_stmt(struct netlink_linearize_ctx *ctx,
 		return netlink_gen_flow_offload_stmt(ctx, stmt);
 	case STMT_OBJREF:
 		return netlink_gen_objref_stmt(ctx, stmt);
+	case STMT_MAP:
+		return netlink_gen_map_stmt(ctx, stmt);
 	default:
 		BUG("unknown statement type %s\n", stmt->ops->name);
 	}
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 5f84d794..6fba7e59 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -577,6 +577,8 @@ int nft_lex(void *, void *, void *);
 %type <stmt>			set_stmt
 %destructor { stmt_free($$); }	set_stmt
 %type <val>			set_stmt_op
+%type <stmt>			map_stmt
+%destructor { stmt_free($$); }	map_stmt
 %type <stmt>			meter_stmt meter_stmt_alloc flow_stmt_legacy_alloc
 %destructor { stmt_free($$); }	meter_stmt meter_stmt_alloc flow_stmt_legacy_alloc
 
@@ -2046,6 +2048,7 @@ stmt			:	verdict_stmt
 			|	dup_stmt
 			|	fwd_stmt
 			|	set_stmt
+			|	map_stmt
 			;
 
 verdict_stmt		:	verdict_expr
@@ -2716,6 +2719,15 @@ set_stmt_op		:	ADD	{ $$ = NFT_DYNSET_OP_ADD; }
 			|	UPDATE	{ $$ = NFT_DYNSET_OP_UPDATE; }
 			;
 
+map_stmt		:	set_stmt_op	MAP '{'	set_elem_expr_stmt	COLON	set_elem_expr_stmt	'}'	symbol_expr
+			{
+				$$ = map_stmt_alloc(&@$);
+				$$->map.op  = $1;
+				$$->map.map = map_expr_alloc(&@$, $4, $6);
+				$$->map.set = $8;
+			}
+			;
+
 meter_stmt		:	flow_stmt_legacy_alloc		flow_stmt_opts	'{' meter_key_expr stmt '}'
 			{
 				$1->meter.key  = $4;
diff --git a/src/statement.c b/src/statement.c
index 701337d7..61ba643b 100644
--- a/src/statement.c
+++ b/src/statement.c
@@ -639,6 +639,34 @@ struct stmt *set_stmt_alloc(const struct location *loc)
 	return stmt_alloc(loc, &set_stmt_ops);
 }
 
+static void map_stmt_print(const struct stmt *stmt, struct output_ctx *octx)
+{
+	nft_print(octx, "%s map { ", set_stmt_op_names[stmt->map.op]);
+	expr_print(stmt->map.map->map->key, octx);
+	nft_print(octx, " : ");
+	expr_print(stmt->map.map->mappings, octx);
+	nft_print(octx, " } ");
+	expr_print(stmt->map.set, octx);
+}
+
+static void map_stmt_destroy(struct stmt *stmt)
+{
+	expr_free(stmt->map.map);
+	expr_free(stmt->map.set);
+}
+
+static const struct stmt_ops map_stmt_ops = {
+	.type		= STMT_MAP,
+	.name		= "map",
+	.print		= map_stmt_print,
+	.destroy	= map_stmt_destroy,
+};
+
+struct stmt *map_stmt_alloc(const struct location *loc)
+{
+	return stmt_alloc(loc, &map_stmt_ops);
+}
+
 static void dup_stmt_print(const struct stmt *stmt, struct output_ctx *octx)
 {
 	nft_print(octx, "dup");