netlink_linearize: skip set element expression in map statement key

This fix is similar to 22d201010919 ("netlink_linearize: skip set element
expression in set statement key") to fix map statement.

netlink_gen_map_stmt() relies on the map key, that is expressed as a set
element. Use the set element key instead to skip the set element wrap,
otherwise get_register() abort execution:

  nft: netlink_linearize.c:650: netlink_gen_expr: Assertion `dreg < ctx->reg_low' failed.

This includes JSON support to make this feature complete and it updates
tests/shell to cover for this support.

Reported-by: Luci Stanescu <luci@cnix.ro>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

4 files changed, 81 insertions, 3 deletions

diff --git a/src/json.c b/src/json.c
index 220ce0f7..1be58221 100644
--- a/src/json.c
+++ b/src/json.c
@@ -1520,6 +1520,25 @@ json_t *set_stmt_json(const struct stmt *stmt, struct output_ctx *octx)
 	return json_pack("{s:o}", "set", root);
 }
 
+json_t *map_stmt_json(const struct stmt *stmt, struct output_ctx *octx)
+{
+	json_t *root;
+
+	root = json_pack("{s:s, s:o, s:o, s:s+}",
+			 "op", set_stmt_op_names[stmt->map.op],
+			 "elem", expr_print_json(stmt->map.key, octx),
+			 "data", expr_print_json(stmt->map.data, octx),
+			 "map", "@", stmt->map.set->set->handle.set.name);
+
+	if (!list_empty(&stmt->map.stmt_list)) {
+		json_object_set_new(root, "stmt",
+				    set_stmt_list_json(&stmt->map.stmt_list,
+						       octx));
+	}
+
+	return json_pack("{s:o}", "map", root);
+}
+
 json_t *objref_stmt_json(const struct stmt *stmt, struct output_ctx *octx)
 {
 	const char *name;
diff --git a/src/netlink_linearize.c b/src/netlink_linearize.c
index 53a318aa..c9121158 100644
--- a/src/netlink_linearize.c
+++ b/src/netlink_linearize.c
@@ -1585,13 +1585,13 @@ static void netlink_gen_map_stmt(struct netlink_linearize_ctx *ctx,
 	int num_stmts = 0;
 	struct stmt *this;
 
-	sreg_key = get_register(ctx, stmt->map.key);
-	netlink_gen_expr(ctx, stmt->map.key, sreg_key);
+	sreg_key = get_register(ctx, stmt->map.key->key);
+	netlink_gen_expr(ctx, stmt->map.key->key, sreg_key);
 
 	sreg_data = get_register(ctx, stmt->map.data);
 	netlink_gen_expr(ctx, stmt->map.data, sreg_data);
 
-	release_register(ctx, stmt->map.key);
+	release_register(ctx, stmt->map.key->key);
 	release_register(ctx, stmt->map.data);
 
 	nle = alloc_nft_expr("dynset");
diff --git a/src/parser_json.c b/src/parser_json.c
index 16961d60..f03037af 100644
--- a/src/parser_json.c
+++ b/src/parser_json.c
@@ -2416,6 +2416,63 @@ static struct stmt *json_parse_set_stmt(struct json_ctx *ctx,
 	return stmt;
 }
 
+static struct stmt *json_parse_map_stmt(struct json_ctx *ctx,
+					const char *key, json_t *value)
+{
+	struct expr *expr, *expr2, *expr_data;
+	json_t *elem, *data, *stmt_json;
+	const char *opstr, *set;
+	struct stmt *stmt;
+	int op;
+
+	if (json_unpack_err(ctx, value, "{s:s, s:o, s:o, s:s}",
+			    "op", &opstr, "elem", &elem, "data", &data, "map", &set))
+		return NULL;
+
+	if (!strcmp(opstr, "add")) {
+		op = NFT_DYNSET_OP_ADD;
+	} else if (!strcmp(opstr, "update")) {
+		op = NFT_DYNSET_OP_UPDATE;
+	} else if (!strcmp(opstr, "delete")) {
+		op = NFT_DYNSET_OP_DELETE;
+	} else {
+		json_error(ctx, "Unknown map statement op '%s'.", opstr);
+		return NULL;
+	}
+
+	expr = json_parse_set_elem_expr_stmt(ctx, elem);
+	if (!expr) {
+		json_error(ctx, "Illegal map statement element.");
+		return NULL;
+	}
+
+	expr_data = json_parse_set_elem_expr_stmt(ctx, data);
+	if (!expr_data) {
+		json_error(ctx, "Illegal map expression data.");
+		expr_free(expr);
+		return NULL;
+	}
+
+	if (set[0] != '@') {
+		json_error(ctx, "Illegal map reference in map statement.");
+		expr_free(expr);
+		expr_free(expr_data);
+		return NULL;
+	}
+	expr2 = symbol_expr_alloc(int_loc, SYMBOL_SET, NULL, set + 1);
+
+	stmt = map_stmt_alloc(int_loc);
+	stmt->map.op = op;
+	stmt->map.key = expr;
+	stmt->map.data = expr_data;
+	stmt->map.set = expr2;
+
+	if (!json_unpack(value, "{s:o}", "stmt", &stmt_json))
+		json_parse_set_stmt_list(ctx, &stmt->set.stmt_list, stmt_json);
+
+	return stmt;
+}
+
 static int json_parse_log_flag(struct json_ctx *ctx,
 			       json_t *root, int *flags)
 {
@@ -2840,6 +2897,7 @@ static struct stmt *json_parse_stmt(struct json_ctx *ctx, json_t *root)
 		{ "redirect", json_parse_nat_stmt },
 		{ "reject", json_parse_reject_stmt },
 		{ "set", json_parse_set_stmt },
+		{ "map", json_parse_map_stmt },
 		{ "log", json_parse_log_stmt },
 		{ "ct helper", json_parse_cthelper_stmt },
 		{ "ct timeout", json_parse_cttimeout_stmt },
diff --git a/src/statement.c b/src/statement.c
index 66424eb4..a9fefc36 100644
--- a/src/statement.c
+++ b/src/statement.c
@@ -848,6 +848,7 @@ static const struct stmt_ops map_stmt_ops = {
 	.name		= "map",
 	.print		= map_stmt_print,
 	.destroy	= map_stmt_destroy,
+	.json		= map_stmt_json,
 };
 
 struct stmt *map_stmt_alloc(const struct location *loc)