src: NAT support for intervals in maps

This patch allows you to specify an interval of IP address in maps.

 table ip x {
        chain y {
                type nat hook postrouting priority srcnat; policy accept;
                snat ip interval to ip saddr map { 10.141.11.4 : 192.168.2.2-192.168.2.4 }
        }
 }

The example above performs SNAT to packets that comes from 10.141.11.4
to an interval of IP addresses from 192.168.2.2 to 192.168.2.4 (both
included).

You can also combine this with dynamic maps:

 table ip x {
        map y {
                type ipv4_addr : interval ipv4_addr
                flags interval
                elements = { 10.141.10.0/24 : 192.168.2.2-192.168.2.4 }
        }

        chain y {
                type nat hook postrouting priority srcnat; policy accept;
                snat ip interval to ip saddr map @y
        }
 }

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

10 files changed, 250 insertions, 4 deletions

diff --git a/include/expression.h b/include/expression.h
index 87c39e5d..35934827 100644
--- a/include/expression.h
+++ b/include/expression.h
@@ -184,6 +184,7 @@ const struct expr_ops *expr_ops_by_type(enum expr_types etype);
  * @EXPR_F_PROTOCOL:		expressions describes upper layer protocol
  * @EXPR_F_INTERVAL_END:	set member ends an open interval
  * @EXPR_F_BOOLEAN:		expression is boolean (set by relational expr on LHS)
+ * @EXPR_F_INTERVAL:		expression describes a interval
  */
 enum expr_flags {
 	EXPR_F_CONSTANT		= 0x1,
@@ -191,6 +192,7 @@ enum expr_flags {
 	EXPR_F_PROTOCOL		= 0x4,
 	EXPR_F_INTERVAL_END	= 0x8,
 	EXPR_F_BOOLEAN		= 0x10,
+	EXPR_F_INTERVAL		= 0x20,
 };
 
 #include <payload.h>
diff --git a/include/statement.h b/include/statement.h
index 8fb459ca..8427f47e 100644
--- a/include/statement.h
+++ b/include/statement.h
@@ -119,6 +119,10 @@ enum nft_nat_etypes {
 
 extern const char *nat_etype2str(enum nft_nat_etypes type);
 
+enum {
+	STMT_NAT_F_INTERVAL	= (1 << 0),
+};
+
 struct nat_stmt {
 	enum nft_nat_etypes	type;
 	struct expr		*addr;
@@ -126,6 +130,7 @@ struct nat_stmt {
 	uint32_t		flags;
 	uint8_t			family;
 	bool			ipportmap;
+	uint32_t		type_flags;
 };
 
 extern struct stmt *nat_stmt_alloc(const struct location *loc,
diff --git a/src/evaluate.c b/src/evaluate.c
index 759b1736..a116f7b6 100644
--- a/src/evaluate.c
+++ b/src/evaluate.c
@@ -1446,6 +1446,9 @@ static int expr_evaluate_map(struct eval_ctx *ctx, struct expr **expr)
 		if (binop_transfer(ctx, expr) < 0)
 			return -1;
 
+		if (ctx->set->data->flags & EXPR_F_INTERVAL)
+			ctx->set->data->len *= 2;
+
 		ctx->set->key->len = ctx->ectx.len;
 		ctx->set = NULL;
 		map = *expr;
@@ -1486,6 +1489,7 @@ static int expr_evaluate_mapping(struct eval_ctx *ctx, struct expr **expr)
 {
 	struct expr *mapping = *expr;
 	struct set *set = ctx->set;
+	uint32_t datalen;
 
 	if (set == NULL)
 		return expr_error(ctx->msgs, mapping,
@@ -1502,7 +1506,13 @@ static int expr_evaluate_mapping(struct eval_ctx *ctx, struct expr **expr)
 	mapping->flags |= mapping->left->flags & EXPR_F_SINGLETON;
 
 	if (set->data) {
-		expr_set_context(&ctx->ectx, set->data->dtype, set->data->len);
+		if (!set_is_anonymous(set->flags) &&
+		    set->data->flags & EXPR_F_INTERVAL)
+			datalen = set->data->len / 2;
+		else
+			datalen = set->data->len;
+
+		expr_set_context(&ctx->ectx, set->data->dtype, datalen);
 	} else {
 		assert((set->flags & NFT_SET_MAP) == 0);
 	}
@@ -1512,7 +1522,14 @@ static int expr_evaluate_mapping(struct eval_ctx *ctx, struct expr **expr)
 	if (!expr_is_constant(mapping->right))
 		return expr_error(ctx->msgs, mapping->right,
 				  "Value must be a constant");
-	if (!expr_is_singleton(mapping->right))
+
+	if (set_is_anonymous(set->flags) &&
+	    (mapping->right->etype == EXPR_RANGE ||
+	     mapping->right->etype == EXPR_PREFIX))
+		set->data->flags |= EXPR_F_INTERVAL;
+
+	if (!(set->data->flags & EXPR_F_INTERVAL) &&
+	    !expr_is_singleton(mapping->right))
 		return expr_error(ctx->msgs, mapping->right,
 				  "Value must be a singleton");
 
@@ -2970,6 +2987,27 @@ static int stmt_evaluate_nat(struct eval_ctx *ctx, struct stmt *stmt)
 		if (err < 0)
 			return err;
 	}
+
+	if (stmt->nat.type_flags & STMT_NAT_F_INTERVAL) {
+		switch (stmt->nat.addr->etype) {
+		case EXPR_MAP:
+			if (!(stmt->nat.addr->mappings->set->data->flags & EXPR_F_INTERVAL))
+				return expr_error(ctx->msgs, stmt->nat.addr,
+						  "map is not defined as interval");
+			break;
+		case EXPR_RANGE:
+		case EXPR_PREFIX:
+			break;
+		default:
+			return expr_error(ctx->msgs, stmt->nat.addr,
+					  "neither prefix, range nor map expression");
+		}
+
+		stmt->flags |= STMT_F_TERMINAL;
+
+		return 0;
+	}
+
 	if (stmt->nat.proto != NULL) {
 		err = nat_evaluate_transport(ctx, stmt, &stmt->nat.proto);
 		if (err < 0)
@@ -3477,6 +3515,9 @@ static int set_evaluate(struct eval_ctx *ctx, struct set *set)
 			return set_error(ctx, set, "map definition does not "
 					 "specify mapping data type");
 
+		if (set->data->flags & EXPR_F_INTERVAL)
+			set->data->len *= 2;
+
 		if (set->data->etype == EXPR_CONCAT &&
 		    expr_evaluate_concat(ctx, &set->data, false) < 0)
 			return -1;
diff --git a/src/mnl.c b/src/mnl.c
index 3c009fab..fb34ecb3 100644
--- a/src/mnl.c
+++ b/src/mnl.c
@@ -1012,8 +1012,11 @@ int mnl_nft_set_add(struct netlink_ctx *ctx, struct cmd *cmd,
 		memory_allocation_error();
 
 	set_key_expression(ctx, set->key, set->flags, udbuf, NFTNL_UDATA_SET_KEY_TYPEOF);
-	if (set->data)
+	if (set->data) {
 		set_key_expression(ctx, set->data, set->flags, udbuf, NFTNL_UDATA_SET_DATA_TYPEOF);
+		nftnl_udata_put_u32(udbuf, NFTNL_UDATA_SET_DATA_INTERVAL,
+				    !!(set->data->flags & EXPR_F_INTERVAL));
+	}
 
 	if (set->desc.field_len[0]) {
 		nftnl_set_set_data(nls, NFTNL_SET_DESC_CONCAT,
diff --git a/src/netlink.c b/src/netlink.c
index 7b7ef39e..10964720 100644
--- a/src/netlink.c
+++ b/src/netlink.c
@@ -176,6 +176,8 @@ static struct nftnl_set_elem *alloc_nftnl_setelem(const struct expr *set,
 			assert(nld.len > 0);
 			/* fallthrough */
 		case EXPR_VALUE:
+		case EXPR_RANGE:
+		case EXPR_PREFIX:
 			nftnl_set_elem_set(nlse, NFTNL_SET_ELEM_DATA,
 					   nld.value, nld.len);
 			break;
@@ -296,6 +298,38 @@ static void netlink_gen_verdict(const struct expr *expr,
 	}
 }
 
+static void netlink_gen_range(const struct expr *expr,
+			      struct nft_data_linearize *nld)
+{
+	unsigned int len = div_round_up(expr->left->len, BITS_PER_BYTE) * 2;
+	unsigned char data[len];
+	unsigned int offset = 0;
+
+	memset(data, 0, len);
+	offset = netlink_export_pad(data, expr->left->value, expr->left);
+	netlink_export_pad(data + offset, expr->right->value, expr->right);
+	memcpy(nld->value, data, len);
+	nld->len = len;
+}
+
+static void netlink_gen_prefix(const struct expr *expr,
+			       struct nft_data_linearize *nld)
+{
+	unsigned int len = div_round_up(expr->len, BITS_PER_BYTE) * 2;
+	unsigned char data[len];
+	int offset;
+	mpz_t v;
+
+	offset = netlink_export_pad(data, expr->prefix->value, expr);
+	mpz_init_bitmask(v, expr->len - expr->prefix_len);
+	mpz_add(v, expr->prefix->value, v);
+	netlink_export_pad(data + offset, v, expr->prefix);
+	mpz_clear(v);
+
+	memcpy(nld->value, data, len);
+	nld->len = len;
+}
+
 void netlink_gen_data(const struct expr *expr, struct nft_data_linearize *data)
 {
 	switch (expr->etype) {
@@ -305,6 +339,10 @@ void netlink_gen_data(const struct expr *expr, struct nft_data_linearize *data)
 		return netlink_gen_concat_data(expr, data);
 	case EXPR_VERDICT:
 		return netlink_gen_verdict(expr, data);
+	case EXPR_RANGE:
+		return netlink_gen_range(expr, data);
+	case EXPR_PREFIX:
+		return netlink_gen_prefix(expr, data);
 	default:
 		BUG("invalid data expression type %s\n", expr_name(expr));
 	}
@@ -618,6 +656,7 @@ static int set_parse_udata_cb(const struct nftnl_udata *attr, void *data)
 	case NFTNL_UDATA_SET_KEYBYTEORDER:
 	case NFTNL_UDATA_SET_DATABYTEORDER:
 	case NFTNL_UDATA_SET_MERGE_ELEMENTS:
+	case NFTNL_UDATA_SET_DATA_INTERVAL:
 		if (len != sizeof(uint32_t))
 			return -1;
 		break;
@@ -701,6 +740,7 @@ struct set *netlink_delinearize_set(struct netlink_ctx *ctx,
 	struct expr *typeof_expr_key, *typeof_expr_data;
 	uint32_t flags, key, objtype = 0;
 	const struct datatype *dtype;
+	uint32_t data_interval = 0;
 	bool automerge = false;
 	const char *udata;
 	struct set *set;
@@ -724,6 +764,7 @@ struct set *netlink_delinearize_set(struct netlink_ctx *ctx,
 		GET_U32_UDATA(keybyteorder, NFTNL_UDATA_SET_KEYBYTEORDER);
 		GET_U32_UDATA(databyteorder, NFTNL_UDATA_SET_DATABYTEORDER);
 		GET_U32_UDATA(automerge, NFTNL_UDATA_SET_MERGE_ELEMENTS);
+		GET_U32_UDATA(data_interval, NFTNL_UDATA_SET_DATA_INTERVAL);
 
 #undef GET_U32_UDATA
 		typeof_expr_key = set_make_key(ud[NFTNL_UDATA_SET_KEY_TYPEOF]);
@@ -792,6 +833,9 @@ struct set *netlink_delinearize_set(struct netlink_ctx *ctx,
 			typeof_expr_key = NULL;
 		}
 
+		if (data_interval)
+			set->data->flags |= EXPR_F_INTERVAL;
+
 		if (dtype != datatype)
 			datatype_free(datatype);
 	}
@@ -885,6 +929,69 @@ void alloc_setelem_cache(const struct expr *set, struct nftnl_set *nls)
 	}
 }
 
+static bool mpz_bitmask_is_prefix(mpz_t bitmask, uint32_t len)
+{
+	unsigned long n1, n2;
+
+        n1 = mpz_scan0(bitmask, 0);
+        if (n1 == ULONG_MAX)
+                return false;
+
+        n2 = mpz_scan1(bitmask, n1 + 1);
+        if (n2 < len)
+                return false;
+
+        return true;
+}
+
+static uint32_t mpz_bitmask_to_prefix(mpz_t bitmask, uint32_t len)
+{
+	return len - mpz_scan0(bitmask, 0);
+}
+
+static struct expr *expr_range_to_prefix(struct expr *range)
+{
+	struct expr *left = range->left, *right = range->right, *prefix;
+	uint32_t len = left->len, prefix_len;
+	mpz_t bitmask;
+
+	mpz_init2(bitmask, len);
+	mpz_xor(bitmask, left->value, right->value);
+
+	if (mpz_bitmask_is_prefix(bitmask, len)) {
+		prefix_len = mpz_bitmask_to_prefix(bitmask, len);
+		prefix = prefix_expr_alloc(&range->location, expr_get(left),
+					   prefix_len);
+		mpz_clear(bitmask);
+		expr_free(range);
+
+		return prefix;
+	}
+	mpz_clear(bitmask);
+
+	return range;
+}
+
+static struct expr *netlink_parse_interval_elem(const struct datatype *dtype,
+						struct expr *expr)
+{
+	unsigned int len = div_round_up(expr->len, BITS_PER_BYTE);
+	struct expr *range, *left, *right;
+	char data[len];
+
+	mpz_export_data(data, expr->value, dtype->byteorder, len);
+	left = constant_expr_alloc(&internal_location, dtype,
+				   dtype->byteorder,
+				   (len / 2) * BITS_PER_BYTE, &data[0]);
+	right = constant_expr_alloc(&internal_location, dtype,
+				    dtype->byteorder,
+				    (len / 2) * BITS_PER_BYTE, &data[len / 2]);
+	range = range_expr_alloc(&expr->location, left, right);
+	expr_free(expr);
+
+	return expr_range_to_prefix(range);
+}
+
 static struct expr *netlink_parse_concat_elem(const struct datatype *dtype,
 					      struct expr *data)
 {
@@ -1021,7 +1128,9 @@ key_end:
 		datatype_set(data, set->data->dtype);
 		data->byteorder = set->data->byteorder;
 
-		if (set->data->dtype->subtypes)
+		if (set->data->flags & EXPR_F_INTERVAL)
+			data = netlink_parse_interval_elem(set->data->dtype, data);
+		else if (set->data->dtype->subtypes)
 			data = netlink_parse_concat_elem(set->data->dtype, data);
 
 		if (data->byteorder == BYTEORDER_HOST_ENDIAN)
diff --git a/src/netlink_delinearize.c b/src/netlink_delinearize.c
index 79efda12..f41223a8 100644
--- a/src/netlink_delinearize.c
+++ b/src/netlink_delinearize.c
@@ -979,6 +979,38 @@ static void netlink_parse_reject(struct netlink_parse_ctx *ctx,
 	ctx->stmt = stmt;
 }
 
+static bool is_nat_addr_map(const struct expr *addr, uint8_t family)
+{
+	const struct expr *mappings, *data;
+	const struct set *set;
+
+	if (!addr ||
+	    expr_ops(addr)->type != EXPR_MAP)
+		return false;
+
+	mappings = addr->right;
+	if (expr_ops(mappings)->type != EXPR_SET_REF)
+		return false;
+
+	set = mappings->set;
+	data = set->data;
+
+	if (!(data->flags & EXPR_F_INTERVAL))
+		return false;
+
+	/* if we're dealing with an address:address map,
+	 * the length will be bit_sizeof(addr) + 32 (one register).
+	 */
+	switch (family) {
+	case NFPROTO_IPV4:
+		return data->len == 32 + 32;
+	case NFPROTO_IPV6:
+		return data->len == 128 + 128;
+	}
+
+	return false;
+}
+
 static bool is_nat_proto_map(const struct expr *addr, uint8_t family)
 {
 	const struct expr *mappings, *data;
@@ -1046,6 +1078,13 @@ static void netlink_parse_nat(struct netlink_parse_ctx *ctx,
 		stmt->nat.addr = addr;
 	}
 
+	if (is_nat_addr_map(addr, family)) {
+		stmt->nat.family = family;
+		stmt->nat.type_flags |= STMT_NAT_F_INTERVAL;
+		ctx->stmt = stmt;
+		return;
+	}
+
 	reg2 = netlink_parse_register(nle, NFTNL_EXPR_NAT_REG_ADDR_MAX);
 	if (reg2 && reg2 != reg1) {
 		addr = netlink_get_register(ctx, loc, reg2);
diff --git a/src/netlink_linearize.c b/src/netlink_linearize.c
index e70e63b3..944fcdae 100644
--- a/src/netlink_linearize.c
+++ b/src/netlink_linearize.c
@@ -1117,6 +1117,14 @@ static void netlink_gen_nat_stmt(struct netlink_linearize_ctx *ctx,
 			netlink_gen_expr(ctx, stmt->nat.addr, amin_reg);
 			netlink_put_register(nle, NFTNL_EXPR_NAT_REG_ADDR_MIN,
 					     amin_reg);
+			if (stmt->nat.addr->etype == EXPR_MAP &&
+			    stmt->nat.addr->mappings->set->data->flags & EXPR_F_INTERVAL) {
+				amax_reg = get_register(ctx, NULL);
+				registers++;
+				amin_reg += netlink_register_space(nat_addrlen(family));
+				netlink_put_register(nle, NFTNL_EXPR_NAT_REG_ADDR_MAX,
+						     amin_reg);
+			}
 		}
 
 		if (stmt->nat.ipportmap) {
diff --git a/src/parser_bison.y b/src/parser_bison.y
index 0e04a0e4..731a5b3e 100644
--- a/src/parser_bison.y
+++ b/src/parser_bison.y
@@ -1792,6 +1792,17 @@ map_block		:	/* empty */	{ $$ = $<set>-1; }
 				$1->flags |= NFT_SET_MAP;
 				$$ = $1;
 			}
+			|	map_block	TYPE
+						data_type_expr	COLON	INTERVAL	data_type_expr
+						stmt_separator
+			{
+				$1->key = $3;
+				$1->data = $6;
+				$1->data->flags |= EXPR_F_INTERVAL;
+
+				$1->flags |= NFT_SET_MAP;
+				$$ = $1;
+			}
 			|	map_block	TYPEOF
 						typeof_expr	COLON	typeof_expr
 						stmt_separator
@@ -1803,6 +1814,18 @@ map_block		:	/* empty */	{ $$ = $<set>-1; }
 				$1->flags |= NFT_SET_MAP;
 				$$ = $1;
 			}
+			|	map_block	TYPEOF
+						typeof_expr	COLON	INTERVAL	typeof_expr
+						stmt_separator
+			{
+				$1->key = $3;
+				datatype_set($1->key, $3->dtype);
+				$1->data = $6;
+				$1->data->flags |= EXPR_F_INTERVAL;
+
+				$1->flags |= NFT_SET_MAP;
+				$$ = $1;
+			}
 			|	map_block	TYPE
 						data_type_expr	COLON	COUNTER
 						stmt_separator
@@ -3171,6 +3194,17 @@ nat_stmt_args		:	stmt_expr
 				$<stmt>0->nat.addr = $6;
 				$<stmt>0->nat.ipportmap = true;
 			}
+			|	nf_key_proto INTERVAL TO	stmt_expr
+			{
+				$<stmt>0->nat.family = $1;
+				$<stmt>0->nat.addr = $4;
+				$<stmt>0->nat.type_flags = STMT_NAT_F_INTERVAL;
+			}
+			|	INTERVAL TO	stmt_expr
+			{
+				$<stmt>0->nat.addr = $3;
+				$<stmt>0->nat.type_flags = STMT_NAT_F_INTERVAL;
+			}
 			;
 
 masq_stmt		:	masq_stmt_alloc		masq_stmt_args
diff --git a/src/rule.c b/src/rule.c
index a312693f..633ca136 100644
--- a/src/rule.c
+++ b/src/rule.c
@@ -462,6 +462,9 @@ static void set_print_key_and_data(const struct set *set, struct output_ctx *oct
 
 	if (set_is_datamap(set->flags)) {
 		nft_print(octx, " : ");
+		if (set->data->flags & EXPR_F_INTERVAL)
+			nft_print(octx, "interval ");
+
 		if (use_typeof)
 			expr_print(set->data, octx);
 		else
diff --git a/src/statement.c b/src/statement.c
index 182edac8..5bbc0540 100644
--- a/src/statement.c
+++ b/src/statement.c
@@ -609,6 +609,8 @@ static void nat_stmt_print(const struct stmt *stmt, struct output_ctx *octx)
 
 		if (stmt->nat.ipportmap)
 			nft_print(octx, " addr . port");
+		else if (stmt->nat.type_flags & STMT_NAT_F_INTERVAL)
+			nft_print(octx, " interval");
 
 		nft_print(octx, " to");
 	}