Merge pull request #18007 from fw-strlen/ipv6_masq_and_dnat

Support ipv6 for masquerade and dnat in nspawn and networkd

man/systemd.network.xml

@@ -744,9 +744,14 @@ IPv6Token=prefixstable:2002:da8:1::</programlisting></para>
           <listitem><para>Configures IP masquerading for the network
           interface. If enabled, packets forwarded from the network
           interface will be appear as coming from the local host.
-          Takes a boolean argument. Implies
-          <varname>IPForward=ipv4</varname>. Defaults to
-          <literal>no</literal>.</para></listitem>
+          Takes one of <literal>ipv4</literal>, <literal>ipv6</literal>,
+          <literal>both</literal>, <literal>no</literal>.
+          The setting <literal>yes</literal> is the same as <literal>ipv4</literal> and not as
+          <literal>both</literal>!
+          Defaults to <literal>no</literal>.
+          If enabled, this automatically sets <varname>IPForward</varname> to one of
+          <literal>ipv4</literal>, <literal>ipv6</literal> or <literal>both</literal>.
+          </para></listitem>
         </varlistentry>
         <varlistentry>
           <term><varname>IPv6PrivacyExtensions=</varname></term>

src/network/networkd-address.c

@@ -262,16 +262,23 @@ static int address_set_masquerade(Address *address, bool add) {
         if (!address->link->network)
                 return 0;
 
-        if (!address->link->network->ip_masquerade)
+        if (address->family == AF_INET &&
+            !FLAGS_SET(address->link->network->ip_masquerade, ADDRESS_FAMILY_IPV4))
                 return 0;
 
-        if (address->family != AF_INET)
+        if (address->family == AF_INET6 &&
+            !FLAGS_SET(address->link->network->ip_masquerade, ADDRESS_FAMILY_IPV6))
                 return 0;
 
         if (address->scope >= RT_SCOPE_LINK)
                 return 0;
 
-        if (address->ip_masquerade_done == add)
+        if (address->family == AF_INET &&
+            address->ip_masquerade_done == add)
+                return 0;
+
+        if (address->family == AF_INET6 &&
+            address->ipv6_masquerade_done == add)
                 return 0;
 
         masked = address->in_addr;
@@ -279,11 +286,14 @@ static int address_set_masquerade(Address *address, bool add) {
         if (r < 0)
                 return r;
 
-        r = fw_add_masquerade(&address->link->manager->fw_ctx, add, AF_INET, &masked, address->prefixlen);
+        r = fw_add_masquerade(&address->link->manager->fw_ctx, add, address->family, &masked, address->prefixlen);
         if (r < 0)
                 return r;
 
-        address->ip_masquerade_done = add;
+        if (address->family == AF_INET)
+                address->ip_masquerade_done = add;
+        else if (address->family == AF_INET6)
+                address->ipv6_masquerade_done = add;
 
         return 0;
 }

src/network/networkd-address.h

@@ -38,6 +38,7 @@ typedef struct Address {
 
         bool scope_set:1;
         bool ip_masquerade_done:1;
+        bool ipv6_masquerade_done:1;
         AddressFamily duplicate_address_detection;
 
         /* Called when address become ready */

src/network/networkd-network-gperf.gperf

@@ -111,7 +111,7 @@ Network.DNSSEC,                              config_parse_dnssec_mode,
 Network.DNSSECNegativeTrustAnchors,          config_parse_dnssec_negative_trust_anchors,               0,                             0
 Network.NTP,                                 config_parse_ntp,                                         0,                             offsetof(Network, ntp)
 Network.IPForward,                           config_parse_address_family_with_kernel,                  0,                             offsetof(Network, ip_forward)
-Network.IPMasquerade,                        config_parse_bool,                                        0,                             offsetof(Network, ip_masquerade)
+Network.IPMasquerade,                        config_parse_address_family_compat,                       0,                             offsetof(Network, ip_masquerade)
 Network.IPv6PrivacyExtensions,               config_parse_ipv6_privacy_extensions,                     0,                             offsetof(Network, ipv6_privacy_extensions)
 Network.IPv6AcceptRA,                        config_parse_tristate,                                    0,                             offsetof(Network, ipv6_accept_ra)
 Network.IPv6AcceptRouterAdvertisements,      config_parse_tristate,                                    0,                             offsetof(Network, ipv6_accept_ra)

src/network/networkd-network.c

@@ -208,9 +208,8 @@ int network_verify(Network *network) {
         if (network->link_local < 0)
                 network->link_local = network->bridge ? ADDRESS_FAMILY_NO : ADDRESS_FAMILY_IPV6;
 
-        /* IPMasquerade=yes implies IPForward=yes */
-        if (network->ip_masquerade)
-                network->ip_forward |= ADDRESS_FAMILY_IPV4;
+        /* IPMasquerade implies IPForward */
+        network->ip_forward |= network->ip_masquerade;
 
         network_adjust_ipv6_accept_ra(network);
         network_adjust_dhcp(network);

src/network/networkd-network.h

@@ -110,7 +110,7 @@ struct Network {
         KeepConfiguration keep_configuration;
         char **bind_carrier;
         bool default_route_on_device;
-        bool ip_masquerade;
+        AddressFamily ip_masquerade;
 
         /* DHCP Client Support */
         AddressFamily dhcp;

src/network/networkd-util.c

@@ -61,6 +61,16 @@ DEFINE_CONFIG_PARSE_ENUM(config_parse_link_local_address_family, link_local_addr
 DEFINE_STRING_TABLE_LOOKUP_FROM_STRING(dhcp_deprecated_address_family, AddressFamily);
 DEFINE_STRING_TABLE_LOOKUP(dhcp_lease_server_type, sd_dhcp_lease_server_type);
 
+static AddressFamily address_family_compat_from_string(const char *s) {
+        if (streq_ptr(s, "yes"))         /* compat name */
+                return ADDRESS_FAMILY_IPV4;
+        if (streq_ptr(s, "both"))
+                return ADDRESS_FAMILY_YES;
+        return address_family_from_string(s);
+}
+DEFINE_CONFIG_PARSE_ENUM(config_parse_address_family_compat, address_family_compat,
+                         AddressFamily, "Failed to parse option");
+
 int config_parse_address_family_with_kernel(
                 const char* unit,
                 const char *filename,

src/network/networkd-util.h

@@ -28,6 +28,7 @@ typedef struct NetworkConfigSection {
 
 CONFIG_PARSER_PROTOTYPE(config_parse_link_local_address_family);
 CONFIG_PARSER_PROTOTYPE(config_parse_address_family_with_kernel);
+CONFIG_PARSER_PROTOTYPE(config_parse_address_family_compat);
 
 const char *address_family_to_string(AddressFamily b) _const_;
 AddressFamily address_family_from_string(const char *s) _pure_;

src/nspawn/nspawn-expose-ports.c

@@ -2,6 +2,7 @@
 
 #include "sd-netlink.h"
 
+#include "af-list.h"
 #include "alloc-util.h"
 #include "fd-util.h"
 #include "firewall-util.h"
@@ -82,9 +83,9 @@ void expose_port_free_all(ExposePort *p) {
         }
 }
 
-int expose_port_flush(FirewallContext **fw_ctx, ExposePort* l, union in_addr_union *exposed) {
+int expose_port_flush(FirewallContext **fw_ctx, ExposePort* l, int af, union in_addr_union *exposed) {
         ExposePort *p;
-        int r, af = AF_INET;
+        int r;
 
         assert(exposed);
 
@@ -106,19 +107,19 @@ int expose_port_flush(FirewallContext **fw_ctx, ExposePort* l, union in_addr_uni
                                       p->container_port,
                                       NULL);
                 if (r < 0)
-                        log_warning_errno(r, "Failed to modify firewall: %m");
+                        log_warning_errno(r, "Failed to modify %s firewall: %m", af_to_name(af));
         }
 
         *exposed = IN_ADDR_NULL;
         return 0;
 }
 
-int expose_port_execute(sd_netlink *rtnl, FirewallContext **fw_ctx, ExposePort *l, union in_addr_union *exposed) {
+int expose_port_execute(sd_netlink *rtnl, FirewallContext **fw_ctx, ExposePort *l, int af, union in_addr_union *exposed) {
         _cleanup_free_ struct local_address *addresses = NULL;
         union in_addr_union new_exposed;
         ExposePort *p;
         bool add;
-        int af = AF_INET, r;
+        int r;
 
         assert(exposed);
 
@@ -137,7 +138,7 @@ int expose_port_execute(sd_netlink *rtnl, FirewallContext **fw_ctx, ExposePort *
                 addresses[0].scope < RT_SCOPE_LINK;
 
         if (!add)
-                return expose_port_flush(fw_ctx, l, exposed);
+                return expose_port_flush(fw_ctx, l, af, exposed);
 
         new_exposed = addresses[0].address;
         if (in_addr_equal(af, exposed, &new_exposed))
@@ -160,7 +161,7 @@ int expose_port_execute(sd_netlink *rtnl, FirewallContext **fw_ctx, ExposePort *
                                       p->container_port,
                                       in_addr_is_null(af, exposed) ? NULL : exposed);
                 if (r < 0)
-                        log_warning_errno(r, "Failed to modify firewall: %m");
+                        log_warning_errno(r, "Failed to modify %s firewall: %m", af_to_name(af));
         }
 
         *exposed = new_exposed;

src/nspawn/nspawn-expose-ports.h

@@ -23,5 +23,5 @@ int expose_port_parse(ExposePort **l, const char *s);
 int expose_port_watch_rtnl(sd_event *event, int recv_fd, sd_netlink_message_handler_t handler, void *userdata, sd_netlink **ret);
 int expose_port_send_rtnl(int send_fd);
 
-int expose_port_execute(sd_netlink *rtnl, FirewallContext **fw_ctx, ExposePort *l, union in_addr_union *exposed);
-int expose_port_flush(FirewallContext **fw_ctx, ExposePort* l, union in_addr_union *exposed);
+int expose_port_execute(sd_netlink *rtnl, FirewallContext **fw_ctx, ExposePort *l, int af, union in_addr_union *exposed);
+int expose_port_flush(FirewallContext **fw_ctx, ExposePort* l, int af, union in_addr_union *exposed);

src/nspawn/nspawn.c

@@ -2467,7 +2467,8 @@ static int setup_kmsg(int kmsg_socket) {
 }
 
 struct ExposeArgs {
-        union in_addr_union address;
+        union in_addr_union address4;
+        union in_addr_union address6;
         struct FirewallContext *fw_ctx;
 };
 
@@ -2478,7 +2479,8 @@ static int on_address_change(sd_netlink *rtnl, sd_netlink_message *m, void *user
         assert(m);
         assert(args);
 
-        expose_port_execute(rtnl, &args->fw_ctx, arg_expose_ports, &args->address);
+        expose_port_execute(rtnl, &args->fw_ctx, arg_expose_ports, AF_INET, &args->address4);
+        expose_port_execute(rtnl, &args->fw_ctx, arg_expose_ports, AF_INET6, &args->address6);
         return 0;
 }
 
@@ -4900,7 +4902,8 @@ static int run_container(
                 if (r < 0)
                         return r;
 
-                (void) expose_port_execute(rtnl, &expose_args->fw_ctx, arg_expose_ports, &expose_args->address);
+                (void) expose_port_execute(rtnl, &expose_args->fw_ctx, arg_expose_ports, AF_INET, &expose_args->address4);
+                (void) expose_port_execute(rtnl, &expose_args->fw_ctx, arg_expose_ports, AF_INET6, &expose_args->address6);
         }
 
         rtnl_socket_pair[0] = safe_close(rtnl_socket_pair[0]);
@@ -5027,7 +5030,8 @@ static int run_container(
                 return 0; /* finito */
         }
 
-        expose_port_flush(&expose_args->fw_ctx, arg_expose_ports, &expose_args->address);
+        expose_port_flush(&expose_args->fw_ctx, arg_expose_ports, AF_INET, &expose_args->address4);
+        expose_port_flush(&expose_args->fw_ctx, arg_expose_ports, AF_INET6, &expose_args->address6);
 
         (void) remove_veth_links(veth_name, arg_network_veth_extra);
         *veth_created = false;
@@ -5582,7 +5586,8 @@ finish:
                 (void) rm_rf(p, REMOVE_ROOT);
         }
 
-        expose_port_flush(&fw_ctx, arg_expose_ports, &expose_args.address);
+        expose_port_flush(&fw_ctx, arg_expose_ports, AF_INET,  &expose_args.address4);
+        expose_port_flush(&fw_ctx, arg_expose_ports, AF_INET6, &expose_args.address6);
 
         if (veth_created)
                 (void) remove_veth_links(veth_name, arg_network_veth_extra);

src/shared/firewall-util-nft.c

@@ -9,6 +9,7 @@
 #include <linux/netfilter/nf_nat.h>
 #include <linux/netfilter_ipv4.h>
 #include <netinet/ip.h>
+#include <netinet/ip6.h>
 
 #include "sd-netlink.h"
 
@@ -17,6 +18,7 @@
 #include "firewall-util-private.h"
 #include "in-addr-util.h"
 #include "macro.h"
+#include "memory-util.h"
 #include "socket-util.h"
 #include "time-util.h"
 
@@ -28,6 +30,9 @@
 
 #define UDP_DPORT_OFFSET 2
 
+void nft_in6addr_to_range(const union in_addr_union *source, unsigned int prefixlen,
+                          struct in6_addr *start, struct in6_addr *end);
+
 static int nfnl_netlink_sendv(sd_netlink *nfnl,
                               sd_netlink_message *messages[],
                               size_t msgcount) {
@@ -329,9 +334,13 @@ static int sd_nfnl_message_new_masq_rule(sd_netlink *nfnl, sd_netlink_message **
         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);
+        /* 1st statement: ip saddr @masq_saddr. Place iph->saddr in reg1, resp. ipv6 in reg1..reg4. */
+        if (family == AF_INET)
+                r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct iphdr, saddr),
+                                          sizeof(uint32_t), NFT_REG32_01);
+        else
+                r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct ip6_hdr, ip6_src.s6_addr),
+                                          sizeof(struct in6_addr), NFT_REG32_01);
         if (r < 0)
                 return r;
 
@@ -397,7 +406,7 @@ static int sd_nfnl_message_new_dnat_rule_pre(sd_netlink *nfnl, sd_netlink_messag
         if (r < 0)
                 return r;
 
-        proto_reg = NFT_REG32_02;
+        proto_reg = family == AF_INET ? NFT_REG32_02 : NFT_REG32_05;
         r = nfnl_add_expr_dnat(m, family, NFT_REG32_01, proto_reg);
         if (r < 0)
                 return r;
@@ -411,9 +420,8 @@ static int sd_nfnl_message_new_dnat_rule_pre(sd_netlink *nfnl, sd_netlink_messag
 
 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;
+        static const uint32_t zero = 0, 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;
@@ -426,19 +434,31 @@ static int sd_nfnl_message_new_dnat_rule_out(sd_netlink *nfnl, sd_netlink_messag
         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: exclude 127.0.0.1/8: ip daddr != 127.0.0.1/8, resp. avoid ::1 */
+        if (family == AF_INET) {
+                uint32_t lonet = htobe32(UINT32_C(0x7F000000)), lomask = htobe32(UINT32_C(0xff000000));
 
-        /* 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;
+                r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct iphdr, daddr),
+                                          sizeof(lonet), 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));
+                /* 1st statement (cont.): compare reg1 with 127/8 */
+                r = nfnl_add_expr_cmp(m, NFT_CMP_NEQ, NFT_REG32_01, &lonet, sizeof(lonet));
+        } else {
+                struct in6_addr loaddr = IN6ADDR_LOOPBACK_INIT;
+
+                r = nfnl_add_expr_payload(m, NFT_PAYLOAD_NETWORK_HEADER, offsetof(struct ip6_hdr, ip6_dst.s6_addr),
+                                          sizeof(loaddr), NFT_REG32_01);
+                if (r < 0)
+                        return r;
+
+                r = nfnl_add_expr_cmp(m, NFT_CMP_NEQ, NFT_REG32_01, &loaddr, sizeof(loaddr));
+        }
         if (r < 0)
                 return r;
 
@@ -475,7 +495,7 @@ static int sd_nfnl_message_new_dnat_rule_out(sd_netlink *nfnl, sd_netlink_messag
 
         /* 4th statement: dnat connection to address/port retrieved by the
          * preceding expression. */
-        proto_reg = NFT_REG32_02;
+        proto_reg = family == AF_INET ? NFT_REG32_02 : NFT_REG32_05;
         r = nfnl_add_expr_dnat(m, family, NFT_REG32_01, proto_reg);
         if (r < 0)
                 return r;
@@ -620,10 +640,11 @@ static uint32_t concat_types2(enum nft_key_types a, enum nft_key_types b) {
 #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;
+        size_t msgcnt = 0, i, ip_type_size;
         uint32_t set_id = 0;
+        int ip_type, r;
+
+        assert(IN_SET(family, AF_INET, AF_INET6));
 
         r = sd_nfnl_message_batch_begin(nfnl, &batch[msgcnt]);
         if (r < 0)
@@ -661,6 +682,14 @@ static int fw_nftables_init_family(sd_netlink *nfnl, int family) {
         if (r < 0)
                 goto out_unref;
 
+        if (family == AF_INET) {
+                ip_type_size = sizeof(uint32_t);
+                ip_type = TYPE_IPADDR;
+        } else {
+                assert(family == AF_INET6);
+                ip_type_size = sizeof(struct in6_addr);
+                ip_type = TYPE_IP6ADDR;
+        }
         msgcnt++;
         assert(msgcnt < NFT_INIT_MSGS);
         /* set to store ip address ranges we should masquerade for */
@@ -731,6 +760,10 @@ int fw_nftables_init(FirewallContext *ctx) {
         if (r < 0)
                 return r;
 
+        r = fw_nftables_init_family(nfnl, AF_INET6);
+        if (r < 0)
+                log_debug_errno(r, "Failed to init ipv6 NAT: %m");
+
         ctx->nfnl = TAKE_PTR(nfnl);
         return 0;
 }
@@ -815,6 +848,73 @@ static int fw_nftables_recreate_table(sd_netlink *nfnl, int af, sd_netlink_messa
         return 0;
 }
 
+void nft_in6addr_to_range(const union in_addr_union *source, unsigned int prefixlen,
+                          struct in6_addr *ret_start, struct in6_addr *ret_end) {
+        uint8_t carry = 0;
+        int i, j;
+
+        assert(prefixlen <= 128);
+
+        for (i = 0, j = 15; i < 16; i++) {
+                uint8_t nm;
+
+                nm = 0xFF;
+                if (prefixlen < 8)
+                        nm = 0xFF << (8 - prefixlen);
+
+                ret_start->s6_addr[i] = source->in6.s6_addr[i] & nm;
+                if (prefixlen <= 8 && j == 15) {
+                         carry = 1u << (8 - prefixlen);
+                         j = i;
+                }
+
+                if (prefixlen >= 8)
+                         prefixlen -= 8;
+                else
+                         prefixlen = 0;
+        }
+        *ret_end = *ret_start;
+
+        for (; j >= 0; j--) {
+                uint16_t overflow = ret_end->s6_addr[j] + carry;
+
+                ret_end->s6_addr[j] = overflow;
+                if (overflow <= 0xff)
+                        break;
+                carry = 1;
+        }
+
+        if (memcmp(ret_start, ret_end, sizeof(*ret_start)) > 0)
+                zero(ret_end);
+}
+
+static int nft_message_add_setelem_ip6range(sd_netlink_message *m,
+                                            const union in_addr_union *source,
+                                            unsigned int prefixlen) {
+        struct in6_addr start, end;
+        int r;
+
+        nft_in6addr_to_range(source, prefixlen, &start, &end);
+
+        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;
+
+        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;
+
+        return sd_nfnl_nft_message_add_setelem_end(m);
+}
+
 #define NFT_MASQ_MSGS   3
 
 int fw_nftables_add_masquerade(
@@ -831,6 +931,8 @@ int fw_nftables_add_masquerade(
         if (!source || source_prefixlen == 0)
                 return -EINVAL;
 
+        if (af == AF_INET6 && source_prefixlen < 8)
+                return -EINVAL;
 again:
         r = sd_nfnl_message_batch_begin(ctx->nfnl, &transaction[0]);
         if (r < 0)
@@ -844,7 +946,11 @@ again:
         if (r < 0)
                 goto out_unref;
 
-        r = nft_message_add_setelem_iprange(transaction[tsize], source, source_prefixlen);
+        if (af == AF_INET)
+                 r = nft_message_add_setelem_iprange(transaction[tsize], source, source_prefixlen);
+        else
+                 r = nft_message_add_setelem_ip6range(transaction[tsize], source, source_prefixlen);
+
         if (r < 0)
                 goto out_unref;
 
@@ -881,7 +987,7 @@ int fw_nftables_add_local_dnat(
                 const union in_addr_union *remote,
                 uint16_t remote_port,
                 const union in_addr_union *previous_remote) {
-        uint32_t data[2], key[2];
+        uint32_t data[5], key[2], dlen;
         sd_netlink_message *transaction[NFT_DNAT_MSGS] = {};
         bool retry = true;
         size_t tsize;
@@ -889,9 +995,6 @@ int fw_nftables_add_local_dnat(
 
         assert(add || !previous_remote);
 
-        if (af != AF_INET)
-                return -EAFNOSUPPORT;
-
         if (!IN_SET(protocol, IPPROTO_TCP, IPPROTO_UDP))
                 return -EPROTONOSUPPORT;
 
@@ -908,7 +1011,14 @@ again:
         if (remote_port <= 0)
                 return -EINVAL;
 
-        data[1] = htobe16(remote_port);
+        if (af == AF_INET) {
+                dlen = 8;
+                data[1] = htobe16(remote_port);
+        } else {
+                assert(af == AF_INET6);
+                dlen = sizeof(data);
+                data[4] = htobe16(remote_port);
+        }
 
         r = sd_nfnl_message_batch_begin(ctx->nfnl, &transaction[0]);
         if (r < 0)
@@ -916,23 +1026,29 @@ again:
 
         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;
+        if (add && previous_remote && !in_addr_equal(af, previous_remote, remote)) {
+                if (af == AF_INET)
+                        data[0] = previous_remote->in.s_addr;
+                else
+                        memcpy(data, &previous_remote->in6, sizeof(previous_remote->in6));
 
-                r = nft_del_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, sizeof(data));
+                r = nft_del_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, dlen);
                 if (r < 0)
                         goto out_unref;
 
                 tsize++;
         }
 
-        data[0] = remote->in.s_addr;
+        if (af == AF_INET)
+                data[0] = remote->in.s_addr;
+        else
+                memcpy(data, &remote->in6, sizeof(remote->in6));
 
         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));
+                nft_add_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, dlen);
         else
-                nft_del_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, sizeof(data));
+                nft_del_element(ctx->nfnl, &transaction[tsize], af, NFT_SYSTEMD_DNAT_MAP_NAME, key, sizeof(key), data, dlen);
 
         tsize++;
         assert(tsize < NFT_DNAT_MSGS);
@@ -949,6 +1065,8 @@ again:
                 int tmp = fw_nftables_recreate_table(ctx->nfnl, af, transaction, tsize);
 
                 if (tmp == 0) {
+                        /* table created anew; previous address already gone */
+                        previous_remote = NULL;
                         retry = false;
                         goto again;
                 }

src/test/test-firewall-util.c

@@ -1,11 +1,128 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
+#include <arpa/inet.h>
+#include <stdlib.h>
 
 #include "firewall-util.h"
 #include "log.h"
+#include "random-util.h"
 #include "tests.h"
 
 #define MAKE_IN_ADDR_UNION(a,b,c,d) (union in_addr_union) { .in.s_addr = htobe32((uint32_t) (a) << 24 | (uint32_t) (b) << 16 | (uint32_t) (c) << 8 | (uint32_t) (d))}
 
+void nft_in6addr_to_range(const union in_addr_union *source, unsigned int prefixlen,
+                          struct in6_addr *start, struct in6_addr *end);
+
+static void make_in6_addr_union(const char *addr, union in_addr_union *u) {
+        assert_se(inet_pton(AF_INET6, addr, &u->in6) >= 0);
+}
+
+static bool test_in6_eq(const char *addr, const union in_addr_union *u) {
+        union in_addr_union tmp;
+
+        make_in6_addr_union(addr, &tmp);
+
+        return memcmp(&tmp.in6, &u->in6, sizeof(tmp.in6)) == 0;
+}
+
+static void assert_in6_eq(const union in_addr_union *a, const union in_addr_union *b) {
+        assert_se(memcmp(&a->in6, &b->in6, sizeof(a->in6)) == 0);
+}
+
+static void test_v6(FirewallContext **ctx) {
+        union in_addr_union u = {}, u2 = {};
+        uint8_t prefixlen;
+        int r;
+
+        make_in6_addr_union("dead::beef", &u);
+
+        r = fw_add_masquerade(ctx, true, AF_INET6, &u, 128);
+        if (r < 0)
+                log_error_errno(r, "Failed to modify ipv6 firewall: %m");
+
+        r = fw_add_masquerade(ctx, false, AF_INET6, &u, 128);
+        if (r < 0)
+                log_error_errno(r, "Failed to modify ipv6 firewall: %m");
+
+        r = fw_add_masquerade(ctx, true, AF_INET6, &u, 64);
+        if (r < 0)
+                log_error_errno(r, "Failed to modify ipv6 firewall: %m");
+
+        r = fw_add_masquerade(ctx, false, AF_INET6, &u, 64);
+        if (r < 0)
+                log_error_errno(r, "Failed to modify ipv6 firewall: %m");
+
+        r = fw_add_local_dnat(ctx, true, AF_INET6, IPPROTO_TCP, 4711, &u, 815, NULL);
+        if (r < 0)
+                log_error_errno(r, "Failed to modify firewall: %m");
+
+        make_in6_addr_union("1c3::c01d", &u2);
+        r = fw_add_local_dnat(ctx, true, AF_INET6, IPPROTO_TCP, 4711, &u2, 815, &u);
+        if (r < 0)
+                log_error_errno(r, "Failed to modify firewall: %m");
+
+        r = fw_add_local_dnat(ctx, false, AF_INET6, IPPROTO_TCP, 4711, &u2, 815, NULL);
+        if (r < 0)
+                log_error_errno(r, "Failed to modify firewall: %m");
+
+        prefixlen = random_u32() % (128 + 1 - 8);
+        prefixlen += 8;
+        pseudo_random_bytes(&u, sizeof(u));
+
+        r = fw_add_masquerade(ctx, true, AF_INET6, &u, prefixlen);
+        if (r < 0)
+                log_error_errno(r, "Failed to modify ipv6 firewall: %m");
+
+        r = fw_add_masquerade(ctx, false, AF_INET6, &u, prefixlen);
+        if (r < 0)
+                log_error_errno(r, "Failed to modify ipv6 firewall: %m");
+}
+
+static void test_v6_range(void) {
+        unsigned int prefixlen = 64;
+        union in_addr_union a, b, s;
+
+        make_in6_addr_union("dead:0:0:beef::", &s);
+
+        nft_in6addr_to_range(&s, prefixlen, &a.in6, &b.in6);
+
+        assert_in6_eq(&s, &a);
+        assert_se(test_in6_eq("dead:0:0:bef0::", &b));
+
+        make_in6_addr_union("2001::", &s);
+        prefixlen = 56;
+        nft_in6addr_to_range(&s, prefixlen, &a.in6, &b.in6);
+        assert_in6_eq(&s, &a);
+        assert_se(test_in6_eq("2001:0:0:0100::", &b));
+
+        prefixlen = 48;
+        nft_in6addr_to_range(&s, prefixlen, &a.in6, &b.in6);
+        assert_in6_eq(&s, &a);
+
+        assert_se(test_in6_eq("2001:0:0001::", &b));
+
+        prefixlen = 65;
+        nft_in6addr_to_range(&s, prefixlen, &a.in6, &b.in6);
+        assert_se(test_in6_eq("2001::", &a));
+
+        assert_se(test_in6_eq("2001::8000:0:0:0", &b));
+
+        prefixlen = 66;
+        nft_in6addr_to_range(&s, prefixlen, &a.in6, &b.in6);
+        assert_in6_eq(&s, &a);
+
+        assert_se(test_in6_eq("2001::4000:0:0:0", &b));
+
+        prefixlen = 127;
+        nft_in6addr_to_range(&s, prefixlen, &a.in6, &b.in6);
+        assert_in6_eq(&s, &a);
+        assert_se(test_in6_eq("2001::0002", &b));
+
+        make_in6_addr_union("dead:beef::1", &s);
+        prefixlen = 64;
+        nft_in6addr_to_range(&s, prefixlen, &a.in6, &b.in6);
+        assert_se(test_in6_eq("dead:beef::", &a));
+}
+
 int main(int argc, char *argv[]) {
         _cleanup_(fw_ctx_freep) FirewallContext *ctx;
         int r;
@@ -57,5 +174,8 @@ int main(int argc, char *argv[]) {
         if (r < 0)
                 log_error_errno(r, "Failed to modify firewall: %m");
 
+        test_v6(&ctx);
+        test_v6_range();
+
         return 0;
 }