--- /dev/null
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <arpa/inet.h>
+#include <endian.h>
+#include <errno.h>
+#include <stddef.h>
+#include <string.h>
+#include <linux/netfilter/nf_tables.h>
+#include <linux/netfilter/nf_nat.h>
+#include <linux/netfilter_ipv4.h>
+#include <netinet/ip.h>
+
+#include "sd-netlink.h"
+
+#include "alloc-util.h"
+#include "firewall-util.h"
+#include "firewall-util-private.h"
+#include "in-addr-util.h"
+#include "macro.h"
+#include "socket-util.h"
+#include "time-util.h"
+
+#define NFT_SYSTEMD_DNAT_MAP_NAME "map_port_ipport"
+#define NFT_SYSTEMD_TABLE_NAME "io.systemd.nat"
+#define NFT_SYSTEMD_MASQ_SET_NAME "masq_saddr"
+
+#define NFNL_DEFAULT_TIMEOUT_USECS (1ULL * USEC_PER_SEC)
+
+#define UDP_DPORT_OFFSET 2
+
+static int nfnl_netlink_sendv(sd_netlink *nfnl,
+ sd_netlink_message *messages[],
+ size_t msgcount) {
+ _cleanup_free_ uint32_t *serial = NULL;
+ size_t i;
+ int r;
+
+ assert(msgcount > 0);
+
+ r = sd_netlink_sendv(nfnl, messages, msgcount, &serial);
+ if (r < 0)
+ return r;
+
+ r = 0;
+ for (i = 1; i < msgcount - 1; i++) {
+ int tmp;
+
+ /* If message is an error, this returns embedded errno */
+ tmp = sd_netlink_read(nfnl, serial[i], NFNL_DEFAULT_TIMEOUT_USECS, NULL);
+ if (tmp < 0 && r == 0)
+ r = tmp;
+ }
+
+ return r;
+}
+
+static int nfnl_add_open_expr_container(sd_netlink_message *m, const char *name) {
+ int r;
+
+ r = sd_netlink_message_open_array(m, NFTA_LIST_ELEM);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_string(m, NFTA_EXPR_NAME, name);
+ if (r < 0)
+ return r;
+
+ return sd_netlink_message_open_container_union(m, NFTA_EXPR_DATA, name);
+}
+
+static int nfnl_add_expr_fib(sd_netlink_message *m, uint32_t nft_fib_flags,
+ enum nft_fib_result result,
+ enum nft_registers dreg) {
+ int r;
+
+ r = nfnl_add_open_expr_container(m, "fib");
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_FIB_FLAGS, htobe32(nft_fib_flags));
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_append_u32(m, NFTA_FIB_RESULT, htobe32(result));
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_append_u32(m, NFTA_FIB_DREG, htobe32(dreg));
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_close_container(m); /* NFTA_EXPR_DATA */
+ if (r < 0)
+ return r;
+
+ return sd_netlink_message_close_container(m); /* NFTA_LIST_ELEM */
+}
+
+static int nfnl_add_expr_meta(sd_netlink_message *m, enum nft_meta_keys key,
+ enum nft_registers dreg) {
+ int r;
+
+ r = nfnl_add_open_expr_container(m, "meta");
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_META_KEY, htobe32(key));
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_META_DREG, htobe32(dreg));
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_close_container(m); /* NFTA_EXPR_DATA */
+ if (r < 0)
+ return r;
+
+ return sd_netlink_message_close_container(m); /* NFTA_LIST_ELEM */
+}
+
+static int nfnl_add_expr_payload(sd_netlink_message *m, enum nft_payload_bases pb,
+ uint32_t offset, uint32_t len, enum nft_registers dreg) {
+ int r;
+
+ r = nfnl_add_open_expr_container(m, "payload");
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_PAYLOAD_DREG, htobe32(dreg));
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_append_u32(m, NFTA_PAYLOAD_BASE, htobe32(pb));
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_append_u32(m, NFTA_PAYLOAD_OFFSET, htobe32(offset));
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_append_u32(m, NFTA_PAYLOAD_LEN, htobe32(len));
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_close_container(m); /* NFTA_EXPR_DATA */
+ if (r < 0)
+ return r;
+ return sd_netlink_message_close_container(m); /* NFTA_LIST_ELEM */
+}
+
+static int nfnl_add_expr_lookup_set_data(sd_netlink_message *m, const char *set_name,
+ enum nft_registers sreg) {
+ int r;
+
+ r = nfnl_add_open_expr_container(m, "lookup");
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_string(m, NFTA_LOOKUP_SET, set_name);
+ if (r < 0)
+ return r;
+
+ return sd_netlink_message_append_u32(m, NFTA_LOOKUP_SREG, htobe32(sreg));
+}
+
+static int nfnl_add_expr_lookup_set(sd_netlink_message *m, const char *set_name,
+ enum nft_registers sreg) {
+ int r;
+
+ r = nfnl_add_expr_lookup_set_data(m, set_name, sreg);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_close_container(m); /* NFTA_EXPR_DATA */
+ if (r < 0)
+ return r;
+ return sd_netlink_message_close_container(m); /* NFTA_LIST_ELEM */
+}
+
+static int nfnl_add_expr_lookup_map(sd_netlink_message *m, const char *set_name,
+ enum nft_registers sreg, enum nft_registers dreg) {
+ int r;
+
+ r = nfnl_add_expr_lookup_set_data(m, set_name, sreg);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_LOOKUP_DREG, htobe32(dreg));
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_close_container(m); /* NFTA_EXPR_DATA */
+ if (r < 0)
+ return r;
+
+ return sd_netlink_message_close_container(m); /* NFTA_LIST_ELEM */
+}
+
+static int nfnl_add_expr_data(sd_netlink_message *m, int attr, const void *data, uint32_t dlen) {
+ int r;
+
+ r = sd_netlink_message_open_container(m, attr);
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_append_data(m, NFTA_DATA_VALUE, data, dlen);
+ if (r < 0)
+ return r;
+
+ return sd_netlink_message_close_container(m); /* attr */
+}
+
+static int nfnl_add_expr_cmp_data(sd_netlink_message *m, const void *data, uint32_t dlen) {
+ return nfnl_add_expr_data(m, NFTA_CMP_DATA, data, dlen);
+}
+
+static int nfnl_add_expr_cmp(sd_netlink_message *m, enum nft_cmp_ops cmp_op,
+ enum nft_registers sreg, const void *data, uint32_t dlen) {
+ int r;
+
+ r = nfnl_add_open_expr_container(m, "cmp");
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_CMP_OP, htobe32(cmp_op));
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_append_u32(m, NFTA_CMP_SREG, htobe32(sreg));
+ if (r < 0)
+ return r;
+
+ r = nfnl_add_expr_cmp_data(m, data, dlen);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_close_container(m); /* NFTA_EXPR_DATA */
+ if (r < 0)
+ return r;
+ return sd_netlink_message_close_container(m); /* NFTA_LIST_ELEM */
+}
+
+static int nfnl_add_expr_bitwise(sd_netlink_message *m,
+ enum nft_registers sreg,
+ enum nft_registers dreg,
+ const void *and,
+ const void *xor, uint32_t len) {
+ int r;
+
+ r = nfnl_add_open_expr_container(m, "bitwise");
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_BITWISE_SREG, htobe32(sreg));
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_append_u32(m, NFTA_BITWISE_DREG, htobe32(dreg));
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_append_u32(m, NFTA_BITWISE_LEN, htobe32(len));
+ if (r < 0)
+ return r;
+
+ r = nfnl_add_expr_data(m, NFTA_BITWISE_MASK, and, len);
+ if (r < 0)
+ return r;
+
+ r = nfnl_add_expr_data(m, NFTA_BITWISE_XOR, xor, len);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_close_container(m); /* NFTA_EXPR_DATA */
+ if (r < 0)
+ return r;
+ return sd_netlink_message_close_container(m); /* NFTA_LIST_ELEM */
+}
+
+static int nfnl_add_expr_dnat(sd_netlink_message *m,
+ int family,
+ enum nft_registers areg,
+ enum nft_registers preg) {
+ int r;
+
+ r = nfnl_add_open_expr_container(m, "nat");
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_NAT_TYPE, htobe32(NFT_NAT_DNAT));
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_NAT_FAMILY, htobe32(family));
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_NAT_REG_ADDR_MIN, htobe32(areg));
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_append_u32(m, NFTA_NAT_REG_PROTO_MIN, htobe32(preg));
+ if (r < 0)
+ return r;
+ r = sd_netlink_message_close_container(m);
+ if (r < 0)
+ return r;
+
+ return sd_netlink_message_close_container(m);
+}
+
+static int nfnl_add_expr_masq(sd_netlink_message *m) {
+ int r;
+
+ r = sd_netlink_message_open_array(m, NFTA_LIST_ELEM);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_string(m, NFTA_EXPR_NAME, "masq");
+ if (r < 0)
+ return r;
+
+ return sd_netlink_message_close_container(m); /* NFTA_LIST_ELEM */
+}
+
+/* -t nat -A POSTROUTING -p protocol -s source/pflen -o out_interface -d destionation/pflen -j MASQUERADE */
+static int sd_nfnl_message_new_masq_rule(sd_netlink *nfnl, sd_netlink_message **ret, int family,
+ const char *chain) {
+ _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+ int r;
+
+ r = sd_nfnl_nft_message_new_rule(nfnl, &m, family, NFT_SYSTEMD_TABLE_NAME, chain);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_open_container(m, NFTA_RULE_EXPRESSIONS);
+ if (r < 0)
+ return r;
+
+ /* 1st statement: ip saddr @masq_saddr. Place iph->saddr in reg1. */
+ r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct iphdr, saddr),
+ sizeof(uint32_t), NFT_REG32_01);
+ if (r < 0)
+ return r;
+
+ /* 1st statement: use reg1 content to make lookup in @masq_saddr set. */
+ r = nfnl_add_expr_lookup_set(m, NFT_SYSTEMD_MASQ_SET_NAME, NFT_REG32_01);
+ if (r < 0)
+ return r;
+
+ /* 2nd statement: masq. Only executed by kernel if the previous lookup was successful. */
+ r = nfnl_add_expr_masq(m);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_close_container(m); /* NFTA_RULE_EXPRESSIONS */
+ if (r < 0)
+ return r;
+ *ret = TAKE_PTR(m);
+ return 0;
+}
+
+/* -t nat -A PREROUTING -p protocol --dport local_port -i in_interface -s source/pflen -d destionation/pflen -j DNAT --to-destination remote_addr:remote_port */
+static int sd_nfnl_message_new_dnat_rule_pre(sd_netlink *nfnl, sd_netlink_message **ret, int family,
+ const char *chain) {
+ _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+ enum nft_registers proto_reg;
+ uint32_t local = RTN_LOCAL;
+ int r;
+
+ r = sd_nfnl_nft_message_new_rule(nfnl, &m, family, NFT_SYSTEMD_TABLE_NAME, chain);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_open_container(m, NFTA_RULE_EXPRESSIONS);
+ if (r < 0)
+ return r;
+
+ /* 1st statement: fib daddr type local */
+ r = nfnl_add_expr_fib(m, NFTA_FIB_F_DADDR, NFT_FIB_RESULT_ADDRTYPE, NFT_REG32_01);
+ if (r < 0)
+ return r;
+
+ /* 1st statement (cont.): compare RTN_LOCAL */
+ r = nfnl_add_expr_cmp(m, NFT_CMP_EQ, NFT_REG32_01, &local, sizeof(local));
+ if (r < 0)
+ return r;
+
+ /* 2nd statement: lookup local port in map, fetch address:dport to map to */
+ r = nfnl_add_expr_meta(m, NFT_META_L4PROTO, NFT_REG32_01);
+ if (r < 0)
+ return r;
+
+ r = nfnl_add_expr_payload(m, NFT_PAYLOAD_TRANSPORT_HEADER, UDP_DPORT_OFFSET,
+ sizeof(uint16_t), NFT_REG32_02);
+ if (r < 0)
+ return r;
+
+ /* 3rd statement: lookup 'l4proto . dport', e.g. 'tcp . 22' as key and
+ * store address and port for the dnat mapping in REG1/REG2.
+ */
+ r = nfnl_add_expr_lookup_map(m, NFT_SYSTEMD_DNAT_MAP_NAME, NFT_REG32_01, NFT_REG32_01);
+ if (r < 0)
+ return r;
+
+ proto_reg = NFT_REG32_02;
+ r = nfnl_add_expr_dnat(m, family, NFT_REG32_01, proto_reg);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_close_container(m); /* NFTA_RULE_EXPRESSIONS */
+ if (r < 0)
+ return r;
+ *ret = TAKE_PTR(m);
+ return 0;
+}
+
+static int sd_nfnl_message_new_dnat_rule_out(sd_netlink *nfnl, sd_netlink_message **ret,
+ int family, const char *chain) {
+ static const uint32_t zero, one = 1;
+
+ uint32_t lonet = htobe32(0x7F000000), lomask = htobe32(0xff000000);
+ _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+ enum nft_registers proto_reg;
+ int r;
+
+ r = sd_nfnl_nft_message_new_rule(nfnl, &m, family, NFT_SYSTEMD_TABLE_NAME, chain);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_open_container(m, NFTA_RULE_EXPRESSIONS);
+ if (r < 0)
+ return r;
+
+ /* 1st statement: exclude 127.0.0.1/8: ip daddr != 127.0.0.1/8 */
+ r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct iphdr, daddr),
+ sizeof(uint32_t), NFT_REG32_01);
+ if (r < 0)
+ return r;
+
+ /* 1st statement (cont.): bitops/prefix */
+ r = nfnl_add_expr_bitwise(m, NFT_REG32_01, NFT_REG32_01, &lomask, &zero, sizeof(lomask));
+ if (r < 0)
+ return r;
+
+ /* 1st statement (cont.): compare reg1 with 127/8 */
+ r = nfnl_add_expr_cmp(m, NFT_CMP_NEQ, NFT_REG32_01, &lonet, sizeof(lonet));
+ if (r < 0)
+ return r;
+
+ /* 2nd statement: meta oif lo */
+ r = nfnl_add_expr_meta(m, NFT_META_OIF, NFT_REG32_01);
+ if (r < 0)
+ return r;
+
+ /* 2nd statement (cont.): compare to lo ifindex (1) */
+ r = nfnl_add_expr_cmp(m, NFT_CMP_EQ, NFT_REG32_01, &one, sizeof(one));
+ if (r < 0)
+ return r;
+
+ /* 3rd statement: meta l4proto . th dport dnat ip . port to map @map_port_ipport */
+ r = nfnl_add_expr_meta(m, NFT_META_L4PROTO, NFT_REG32_01);
+ if (r < 0)
+ return r;
+
+ /* 3rd statement (cont): store the port number in reg2 */
+ r = nfnl_add_expr_payload(m, NFT_PAYLOAD_TRANSPORT_HEADER, UDP_DPORT_OFFSET,
+ sizeof(uint16_t), NFT_REG32_02);
+ if (r < 0)
+ return r;
+
+ /* 3rd statement (cont): use reg1 and reg2 and retrieve
+ * the new destination ip and port number.
+ *
+ * reg1 and reg2 are clobbered and will then contain the new
+ * address/port number.
+ */
+ r = nfnl_add_expr_lookup_map(m, NFT_SYSTEMD_DNAT_MAP_NAME, NFT_REG32_01, NFT_REG32_01);
+ if (r < 0)
+ return r;
+
+ /* 4th statement: dnat connection to address/port retrieved by the
+ * preceeding expression. */
+ proto_reg = NFT_REG32_02;
+ r = nfnl_add_expr_dnat(m, family, NFT_REG32_01, proto_reg);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_close_container(m); /* NFTA_RULE_EXPRESSIONS */
+ if (r < 0)
+ return r;
+ *ret = TAKE_PTR(m);
+ return 0;
+}
+
+static int nft_new_set(struct sd_netlink *nfnl,
+ sd_netlink_message **ret,
+ int family, const char *set_name,
+ uint32_t set_id,
+ uint32_t flags, uint32_t type, uint32_t klen) {
+ _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+ int r;
+
+ r = sd_nfnl_nft_message_new_set(nfnl, &m, family, NFT_SYSTEMD_TABLE_NAME, set_name, set_id, klen);
+ if (r < 0)
+ return r;
+
+ if (flags != 0) {
+ r = sd_netlink_message_append_u32(m, NFTA_SET_FLAGS, htobe32(flags));
+ if (r < 0)
+ return r;
+ }
+
+ r = sd_netlink_message_append_u32(m, NFTA_SET_KEY_TYPE, htobe32(type));
+ if (r < 0)
+ return r;
+
+ *ret = TAKE_PTR(m);
+ return r;
+}
+
+static int nft_new_map(struct sd_netlink *nfnl,
+ sd_netlink_message **ret,
+ int family, const char *set_name, uint32_t set_id,
+ uint32_t flags, uint32_t type, uint32_t klen, uint32_t dtype, uint32_t dlen) {
+ _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+ int r;
+
+ r = nft_new_set(nfnl, &m, family, set_name, set_id, flags | NFT_SET_MAP, type, klen);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_SET_DATA_TYPE, htobe32(dtype));
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_SET_DATA_LEN, htobe32(dlen));
+ if (r < 0)
+ return r;
+ *ret = TAKE_PTR(m);
+ return 0;
+}
+
+static int nft_add_element(sd_netlink *nfnl, sd_netlink_message **ret,
+ int family, const char *set_name,
+ const void *key, uint32_t klen,
+ const void *data, uint32_t dlen) {
+ _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+ int r;
+
+ /*
+ * Ideally there would be an API that provides:
+ *
+ * 1) a init function to add the main ruleset skeleton
+ * 2) a function that populates the sets with all known address/port pairs to s/dnat for
+ * 3) a function that can remove address/port pairs again.
+ *
+ * At this time, the existing API is used which is built on a
+ * 'add/delete a rule' paradigm.
+ *
+ * This replicated here and each element gets added to the set
+ * one-by-one.
+ */
+ r = sd_nfnl_nft_message_new_setelems_begin(nfnl, &m, family, NFT_SYSTEMD_TABLE_NAME, set_name);
+ if (r < 0)
+ return r;
+
+ r = sd_nfnl_nft_message_add_setelem(m, 0, key, klen, data, dlen);
+ if (r < 0)
+ return r;
+
+ /* could theoretically append more set elements to add here */
+ r = sd_nfnl_nft_message_add_setelem_end(m);
+ if (r < 0)
+ return r;
+ *ret = TAKE_PTR(m);
+ return 0;
+}
+
+static int nft_del_element(sd_netlink *nfnl,
+ sd_netlink_message **ret, int family, const char *set_name,
+ const void *key, uint32_t klen,
+ const void *data, uint32_t dlen) {
+ _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+ int r;
+
+ r = sd_nfnl_nft_message_del_setelems_begin(nfnl, &m, family, NFT_SYSTEMD_TABLE_NAME, set_name);
+ if (r < 0)
+ return r;
+
+ r = sd_nfnl_nft_message_add_setelem(m, 0, key, klen, data, dlen);
+ if (r < 0)
+ return r;
+
+ r = sd_nfnl_nft_message_add_setelem_end(m);
+ if (r < 0)
+ return r;
+ *ret = TAKE_PTR(m);
+ return 0;
+}
+
+/* This is needed so 'nft' userspace tool can properly format the contents
+ * of the set/map when someone uses 'nft' to inspect their content.
+ *
+ * The values cannot be changed, they are part of the nft tool type identifier ABI.
+ */
+#define TYPE_BITS 6
+
+enum nft_key_types {
+ TYPE_IPADDR = 7,
+ TYPE_IP6ADDR = 8,
+ TYPE_INET_PROTOCOL = 12,
+ TYPE_INET_SERVICE = 13,
+};
+
+static uint32_t concat_types2(enum nft_key_types a, enum nft_key_types b) {
+ uint32_t type = (uint32_t)a;
+
+ type <<= TYPE_BITS;
+ type |= (uint32_t)b;
+
+ return type;
+}
+
+/* enough space to hold netlink messages for table skeleton */
+#define NFT_INIT_MSGS 16
+static int fw_nftables_init_family(sd_netlink *nfnl, int family) {
+ sd_netlink_message *batch[NFT_INIT_MSGS] = {};
+ size_t ip_type_size = sizeof(uint32_t);
+ int ip_type = TYPE_IPADDR, r;
+ size_t msgcnt = 0, i;
+ uint32_t set_id = 0;
+
+ r = sd_nfnl_message_batch_begin(nfnl, &batch[msgcnt]);
+ if (r < 0)
+ goto out_unref;
+
+ msgcnt++;
+ assert(msgcnt < NFT_INIT_MSGS);
+ /* Set F_EXCL so table add fails if the table already exists. */
+ r = sd_nfnl_nft_message_new_table(nfnl, &batch[msgcnt], family, NFT_SYSTEMD_TABLE_NAME, NLM_F_EXCL | NLM_F_ACK);
+ if (r < 0)
+ goto out_unref;
+
+ msgcnt++;
+ assert(msgcnt < NFT_INIT_MSGS);
+
+ r = sd_nfnl_nft_message_new_basechain(nfnl, &batch[msgcnt], family, NFT_SYSTEMD_TABLE_NAME,
+ "prerouting", "nat",
+ NF_INET_PRE_ROUTING, NF_IP_PRI_NAT_DST + 1);
+ if (r < 0)
+ goto out_unref;
+
+ msgcnt++;
+ assert(msgcnt < NFT_INIT_MSGS);
+ r = sd_nfnl_nft_message_new_basechain(nfnl, &batch[msgcnt], family, NFT_SYSTEMD_TABLE_NAME,
+ "output", "nat",
+ NF_INET_LOCAL_OUT, NF_IP_PRI_NAT_DST + 1);
+ if (r < 0)
+ goto out_unref;
+
+ msgcnt++;
+ assert(msgcnt < NFT_INIT_MSGS);
+ r = sd_nfnl_nft_message_new_basechain(nfnl, &batch[msgcnt], family, NFT_SYSTEMD_TABLE_NAME,
+ "postrouting", "nat",
+ NF_INET_POST_ROUTING, NF_IP_PRI_NAT_SRC + 1);
+ if (r < 0)
+ goto out_unref;
+
+ msgcnt++;
+ assert(msgcnt < NFT_INIT_MSGS);
+ /* set to store ip address ranges we should masquerade for */
+ r = nft_new_set(nfnl, &batch[msgcnt], family, NFT_SYSTEMD_MASQ_SET_NAME, ++set_id, NFT_SET_INTERVAL, ip_type, ip_type_size);
+ if (r < 0)
+ goto out_unref;
+
+ /*
+ * map to store ip address:port pair to dnat to. elements in concatenation
+ * are rounded up to 4 bytes.
+ *
+ * Example: ip protocol . tcp daddr is sizeof(uint32_t) + sizeof(uint32_t), not
+ * sizeof(uint8_t) + sizeof(uint16_t).
+ */
+ msgcnt++;
+ assert(msgcnt < NFT_INIT_MSGS);
+ r = nft_new_map(nfnl, &batch[msgcnt], family, NFT_SYSTEMD_DNAT_MAP_NAME, ++set_id, 0,
+ concat_types2(TYPE_INET_PROTOCOL, TYPE_INET_SERVICE), sizeof(uint32_t) * 2,
+ concat_types2(ip_type, TYPE_INET_SERVICE), ip_type_size + sizeof(uint32_t));
+ if (r < 0)
+ goto out_unref;
+
+ msgcnt++;
+ assert(msgcnt < NFT_INIT_MSGS);
+ r = sd_nfnl_message_new_dnat_rule_pre(nfnl, &batch[msgcnt], family, "prerouting");
+ if (r < 0)
+ goto out_unref;
+
+ msgcnt++;
+ assert(msgcnt < NFT_INIT_MSGS);
+ r = sd_nfnl_message_new_dnat_rule_out(nfnl, &batch[msgcnt], family, "output");
+ if (r < 0)
+ goto out_unref;
+
+ msgcnt++;
+ r = sd_nfnl_message_new_masq_rule(nfnl, &batch[msgcnt], family, "postrouting");
+ if (r < 0)
+ goto out_unref;
+
+ msgcnt++;
+ assert(msgcnt < NFT_INIT_MSGS);
+ r = sd_nfnl_message_batch_end(nfnl, &batch[msgcnt]);
+ if (r < 0)
+ goto out_unref;
+
+ msgcnt++;
+ assert(msgcnt <= NFT_INIT_MSGS);
+ r = nfnl_netlink_sendv(nfnl, batch, msgcnt);
+ if (r == -EEXIST)
+ r = 0;
+
+out_unref:
+ for (i = 0; i < msgcnt; i++)
+ sd_netlink_message_unref(batch[i]);
+
+ return r;
+}
+
+int fw_nftables_init(FirewallContext *ctx) {
+ _cleanup_(sd_netlink_unrefp) sd_netlink *nfnl = NULL;
+ int r;
+
+ r = sd_nfnl_socket_open(&nfnl);
+ if (r < 0)
+ return r;
+
+ r = fw_nftables_init_family(nfnl, AF_INET);
+ if (r < 0)
+ return r;
+
+ ctx->nfnl = TAKE_PTR(nfnl);
+ return 0;
+}
+
+void fw_nftables_exit(FirewallContext *ctx) {
+ ctx->nfnl = sd_netlink_unref(ctx->nfnl);
+}
+
+static int nft_message_add_setelem_iprange(sd_netlink_message *m,
+ const union in_addr_union *source,
+ unsigned int prefixlen) {
+ uint32_t mask, start, end;
+ unsigned int nplen;
+ int r;
+
+ assert(prefixlen <= 32);
+ nplen = 32 - prefixlen;
+
+ mask = (1U << nplen) - 1U;
+ mask = htobe32(~mask);
+ start = source->in.s_addr & mask;
+
+ r = sd_nfnl_nft_message_add_setelem(m, 0, &start, sizeof(start), NULL, 0);
+ if (r < 0)
+ return r;
+
+ r = sd_nfnl_nft_message_add_setelem_end(m);
+ if (r < 0)
+ return r;
+
+ end = be32toh(start) + (1U << nplen);
+ if (end < be32toh(start))
+ end = 0U;
+ end = htobe32(end);
+
+ r = sd_nfnl_nft_message_add_setelem(m, 1, &end, sizeof(end), NULL, 0);
+ if (r < 0)
+ return r;
+
+ r = sd_netlink_message_append_u32(m, NFTA_SET_ELEM_FLAGS, htobe32(NFT_SET_ELEM_INTERVAL_END));
+ if (r < 0)
+ return r;
+
+ r = sd_nfnl_nft_message_add_setelem_end(m);
+ if (r < 0)
+ return r;
+
+ return 0;
+}
+
+#define NFT_MASQ_MSGS 3
+
+int fw_nftables_add_masquerade(
+ FirewallContext *ctx,
+ bool add,
+ int af,
+ const union in_addr_union *source,
+ unsigned int source_prefixlen) {
+ sd_netlink_message *transaction[NFT_MASQ_MSGS] = {};
+ size_t tsize;
+ int r;
+
+ if (!source || source_prefixlen == 0)
+ return -EINVAL;
+
+ r = sd_nfnl_message_batch_begin(ctx->nfnl, &transaction[0]);
+ if (r < 0)
+ return r;
+ tsize = 1;
+ if (add)
+ r = sd_nfnl_nft_message_new_setelems_begin(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_TABLE_NAME, NFT_SYSTEMD_MASQ_SET_NAME);
+ else
+ r = sd_nfnl_nft_message_del_setelems_begin(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_TABLE_NAME, NFT_SYSTEMD_MASQ_SET_NAME);
+
+ if (r < 0)
+ goto out_unref;
+
+ r = nft_message_add_setelem_iprange(transaction[tsize], source, source_prefixlen);
+ if (r < 0)
+ goto out_unref;
+
+ ++tsize;
+ assert(tsize < NFT_MASQ_MSGS);
+ r = sd_nfnl_message_batch_end(ctx->nfnl, &transaction[tsize]);
+ if (r < 0)
+ return r;
+ ++tsize;
+ r = nfnl_netlink_sendv(ctx->nfnl, transaction, tsize);
+
+out_unref:
+ while (tsize > 0)
+ sd_netlink_message_unref(transaction[--tsize]);
+ return r < 0 ? r : 0;
+}
+
+#define NFT_DNAT_MSGS 4
+
+int fw_nftables_add_local_dnat(
+ FirewallContext *ctx,
+ bool add,
+ int af,
+ int protocol,
+ uint16_t local_port,
+ const union in_addr_union *remote,
+ uint16_t remote_port,
+ const union in_addr_union *previous_remote) {
+ uint32_t data[2], key[2];
+ sd_netlink_message *transaction[NFT_DNAT_MSGS] = {};
+ size_t tsize;
+ int r;
+
+ assert(add || !previous_remote);
+
+ if (af != AF_INET)
+ return -EAFNOSUPPORT;
+
+ if (!IN_SET(protocol, IPPROTO_TCP, IPPROTO_UDP))
+ return -EPROTONOSUPPORT;
+
+ if (local_port <= 0)
+ return -EINVAL;
+
+ key[0] = protocol;
+ key[1] = htobe16(local_port);
+
+ if (!remote)
+ return -EOPNOTSUPP;
+
+ if (remote_port <= 0)
+ return -EINVAL;
+
+ data[1] = htobe16(remote_port);
+
+ r = sd_nfnl_message_batch_begin(ctx->nfnl, &transaction[0]);
+ if (r < 0)
+ return r;
+
+ tsize = 1;
+ /* If a previous remote is set, remove its entry */
+ if (add && previous_remote && previous_remote->in.s_addr != remote->in.s_addr) {
+ data[0] = previous_remote->in.s_addr;
+
+ r = nft_del_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, sizeof(data));
+ if (r < 0)
+ goto out_unref;
+
+ tsize++;
+ }
+
+ data[0] = remote->in.s_addr;
+
+ assert(tsize < NFT_DNAT_MSGS);
+ if (add)
+ nft_add_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, sizeof(data));
+ else
+ nft_del_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, sizeof(data));
+
+ tsize++;
+ assert(tsize < NFT_DNAT_MSGS);
+
+ r = sd_nfnl_message_batch_end(ctx->nfnl, &transaction[tsize]);
+ if (r < 0)
+ goto out_unref;
+
+ tsize++;
+ assert(tsize <= NFT_DNAT_MSGS);
+ r = nfnl_netlink_sendv(ctx->nfnl, transaction, tsize);
+
+out_unref:
+ while (tsize > 0)
+ sd_netlink_message_unref(transaction[--tsize]);
+ return r < 0 ? r : 0;
+}
projects / thirdparty / systemd.git / commitdiff
