path: root/src/network/netdev/netdev.c

/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <net/if.h>
#include <netinet/in.h>
#include <unistd.h>

#include "alloc-util.h"
#include "bareudp.h"
#include "batadv.h"
#include "bond.h"
#include "bridge.h"
#include "conf-files.h"
#include "conf-parser.h"
#include "dummy.h"
#include "fd-util.h"
#include "fou-tunnel.h"
#include "geneve.h"
#include "ifb.h"
#include "ipvlan.h"
#include "l2tp-tunnel.h"
#include "list.h"
#include "macsec.h"
#include "macvlan.h"
#include "netdev.h"
#include "netdevsim.h"
#include "netlink-util.h"
#include "networkd-manager.h"
#include "networkd-queue.h"
#include "nlmon.h"
#include "path-lookup.h"
#include "siphash24.h"
#include "stat-util.h"
#include "string-table.h"
#include "string-util.h"
#include "strv.h"
#include "tunnel.h"
#include "tuntap.h"
#include "vcan.h"
#include "veth.h"
#include "vlan.h"
#include "vrf.h"
#include "vxcan.h"
#include "vxlan.h"
#include "wireguard.h"
#include "xfrm.h"

const NetDevVTable * const netdev_vtable[_NETDEV_KIND_MAX] = {
        [NETDEV_KIND_BATADV] = &batadv_vtable,
        [NETDEV_KIND_BRIDGE] = &bridge_vtable,
        [NETDEV_KIND_BOND] = &bond_vtable,
        [NETDEV_KIND_VLAN] = &vlan_vtable,
        [NETDEV_KIND_MACVLAN] = &macvlan_vtable,
        [NETDEV_KIND_MACVTAP] = &macvtap_vtable,
        [NETDEV_KIND_IPVLAN] = &ipvlan_vtable,
        [NETDEV_KIND_IPVTAP] = &ipvtap_vtable,
        [NETDEV_KIND_VXLAN] = &vxlan_vtable,
        [NETDEV_KIND_IPIP] = &ipip_vtable,
        [NETDEV_KIND_GRE] = &gre_vtable,
        [NETDEV_KIND_GRETAP] = &gretap_vtable,
        [NETDEV_KIND_IP6GRE] = &ip6gre_vtable,
        [NETDEV_KIND_IP6GRETAP] = &ip6gretap_vtable,
        [NETDEV_KIND_SIT] = &sit_vtable,
        [NETDEV_KIND_VTI] = &vti_vtable,
        [NETDEV_KIND_VTI6] = &vti6_vtable,
        [NETDEV_KIND_VETH] = &veth_vtable,
        [NETDEV_KIND_DUMMY] = &dummy_vtable,
        [NETDEV_KIND_TUN] = &tun_vtable,
        [NETDEV_KIND_TAP] = &tap_vtable,
        [NETDEV_KIND_IP6TNL] = &ip6tnl_vtable,
        [NETDEV_KIND_VRF] = &vrf_vtable,
        [NETDEV_KIND_VCAN] = &vcan_vtable,
        [NETDEV_KIND_GENEVE] = &geneve_vtable,
        [NETDEV_KIND_VXCAN] = &vxcan_vtable,
        [NETDEV_KIND_WIREGUARD] = &wireguard_vtable,
        [NETDEV_KIND_NETDEVSIM] = &netdevsim_vtable,
        [NETDEV_KIND_FOU] = &foutnl_vtable,
        [NETDEV_KIND_ERSPAN] = &erspan_vtable,
        [NETDEV_KIND_L2TP] = &l2tptnl_vtable,
        [NETDEV_KIND_MACSEC] = &macsec_vtable,
        [NETDEV_KIND_NLMON] = &nlmon_vtable,
        [NETDEV_KIND_XFRM] = &xfrm_vtable,
        [NETDEV_KIND_IFB] = &ifb_vtable,
        [NETDEV_KIND_BAREUDP] = &bare_udp_vtable,
};

static const char* const netdev_kind_table[_NETDEV_KIND_MAX] = {
        [NETDEV_KIND_BAREUDP] = "bareudp",
        [NETDEV_KIND_BATADV] = "batadv",
        [NETDEV_KIND_BRIDGE] = "bridge",
        [NETDEV_KIND_BOND] = "bond",
        [NETDEV_KIND_VLAN] = "vlan",
        [NETDEV_KIND_MACVLAN] = "macvlan",
        [NETDEV_KIND_MACVTAP] = "macvtap",
        [NETDEV_KIND_IPVLAN] = "ipvlan",
        [NETDEV_KIND_IPVTAP] = "ipvtap",
        [NETDEV_KIND_VXLAN] = "vxlan",
        [NETDEV_KIND_IPIP] = "ipip",
        [NETDEV_KIND_GRE] = "gre",
        [NETDEV_KIND_GRETAP] = "gretap",
        [NETDEV_KIND_IP6GRE] = "ip6gre",
        [NETDEV_KIND_IP6GRETAP] = "ip6gretap",
        [NETDEV_KIND_SIT] = "sit",
        [NETDEV_KIND_VETH] = "veth",
        [NETDEV_KIND_VTI] = "vti",
        [NETDEV_KIND_VTI6] = "vti6",
        [NETDEV_KIND_DUMMY] = "dummy",
        [NETDEV_KIND_TUN] = "tun",
        [NETDEV_KIND_TAP] = "tap",
        [NETDEV_KIND_IP6TNL] = "ip6tnl",
        [NETDEV_KIND_VRF] = "vrf",
        [NETDEV_KIND_VCAN] = "vcan",
        [NETDEV_KIND_GENEVE] = "geneve",
        [NETDEV_KIND_VXCAN] = "vxcan",
        [NETDEV_KIND_WIREGUARD] = "wireguard",
        [NETDEV_KIND_NETDEVSIM] = "netdevsim",
        [NETDEV_KIND_FOU] = "fou",
        [NETDEV_KIND_ERSPAN] = "erspan",
        [NETDEV_KIND_L2TP] = "l2tp",
        [NETDEV_KIND_MACSEC] = "macsec",
        [NETDEV_KIND_NLMON] = "nlmon",
        [NETDEV_KIND_XFRM] = "xfrm",
        [NETDEV_KIND_IFB] = "ifb",
};

DEFINE_STRING_TABLE_LOOKUP(netdev_kind, NetDevKind);

int config_parse_netdev_kind(
                const char *unit,
                const char *filename,
                unsigned line,
                const char *section,
                unsigned section_line,
                const char *lvalue,
                int ltype,
                const char *rvalue,
                void *data,
                void *userdata) {

        NetDevKind k, *kind = data;

        assert(rvalue);
        assert(data);

        k = netdev_kind_from_string(rvalue);
        if (k < 0) {
                log_syntax(unit, LOG_WARNING, filename, line, k, "Failed to parse netdev kind, ignoring assignment: %s", rvalue);
                return 0;
        }

        if (*kind != _NETDEV_KIND_INVALID && *kind != k) {
                log_syntax(unit, LOG_WARNING, filename, line, 0,
                           "Specified netdev kind is different from the previous value '%s', ignoring assignment: %s",
                           netdev_kind_to_string(*kind), rvalue);
                return 0;
        }

        *kind = k;

        return 0;
}

static void netdev_callbacks_clear(NetDev *netdev) {
        netdev_join_callback *callback;

        if (!netdev)
                return;

        while ((callback = netdev->callbacks)) {
                LIST_REMOVE(callbacks, netdev->callbacks, callback);
                link_unref(callback->link);
                free(callback);
        }
}

bool netdev_is_managed(NetDev *netdev) {
        if (!netdev || !netdev->manager || !netdev->ifname)
                return false;

        return hashmap_get(netdev->manager->netdevs, netdev->ifname) == netdev;
}

static void netdev_detach_from_manager(NetDev *netdev) {
        if (netdev->ifname && netdev->manager)
                hashmap_remove(netdev->manager->netdevs, netdev->ifname);
}

static NetDev *netdev_free(NetDev *netdev) {
        assert(netdev);

        netdev_callbacks_clear(netdev);

        netdev_detach_from_manager(netdev);

        free(netdev->filename);

        free(netdev->description);
        free(netdev->ifname);
        free(netdev->mac);
        condition_free_list(netdev->conditions);

        /* Invoke the per-kind done() destructor, but only if the state field is initialized. We conditionalize that
         * because we parse .netdev files twice: once to determine the kind (with a short, minimal NetDev structure
         * allocation, with no room for per-kind fields), and once to read the kind's properties (with a full,
         * comprehensive NetDev structure allocation with enough space for whatever the specific kind needs). Now, in
         * the first case we shouldn't try to destruct the per-kind NetDev fields on destruction, in the second case we
         * should. We use the state field to discern the two cases: it's _NETDEV_STATE_INVALID on the first "raw"
         * call. */
        if (netdev->state != _NETDEV_STATE_INVALID &&
            NETDEV_VTABLE(netdev) &&
            NETDEV_VTABLE(netdev)->done)
                NETDEV_VTABLE(netdev)->done(netdev);

        return mfree(netdev);
}

DEFINE_TRIVIAL_REF_UNREF_FUNC(NetDev, netdev, netdev_free);

void netdev_drop(NetDev *netdev) {
        if (!netdev || netdev->state == NETDEV_STATE_LINGER)
                return;

        netdev->state = NETDEV_STATE_LINGER;

        log_netdev_debug(netdev, "netdev removed");

        netdev_callbacks_clear(netdev);

        netdev_detach_from_manager(netdev);

        netdev_unref(netdev);

        return;
}

int netdev_get(Manager *manager, const char *name, NetDev **ret) {
        NetDev *netdev;

        assert(manager);
        assert(name);
        assert(ret);

        netdev = hashmap_get(manager->netdevs, name);
        if (!netdev) {
                *ret = NULL;
                return -ENOENT;
        }

        *ret = netdev;

        return 0;
}

static int netdev_enter_failed(NetDev *netdev) {
        netdev->state = NETDEV_STATE_FAILED;

        netdev_callbacks_clear(netdev);

        return 0;
}

static int netdev_enslave_ready(NetDev *netdev, Link* link, link_netlink_message_handler_t callback) {
        _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *req = NULL;
        int r;

        assert(netdev);
        assert(netdev->state == NETDEV_STATE_READY);
        assert(netdev->manager);
        assert(netdev->manager->rtnl);
        assert(IN_SET(netdev->kind, NETDEV_KIND_BRIDGE, NETDEV_KIND_BOND, NETDEV_KIND_VRF, NETDEV_KIND_BATADV));
        assert(link);
        assert(callback);

        if (link->flags & IFF_UP && netdev->kind == NETDEV_KIND_BOND) {
                log_netdev_debug(netdev, "Link '%s' was up when attempting to enslave it. Bringing link down.", link->ifname);
                r = link_down(link);
                if (r < 0)
                        return log_netdev_error_errno(netdev, r, "Could not bring link down: %m");
        }

        r = sd_rtnl_message_new_link(netdev->manager->rtnl, &req, RTM_SETLINK, link->ifindex);
        if (r < 0)
                return log_netdev_error_errno(netdev, r, "Could not allocate RTM_SETLINK message: %m");

        r = sd_netlink_message_append_u32(req, IFLA_MASTER, netdev->ifindex);
        if (r < 0)
                return log_netdev_error_errno(netdev, r, "Could not append IFLA_MASTER attribute: %m");

        r = netlink_call_async(netdev->manager->rtnl, NULL, req, callback,
                               link_netlink_destroy_callback, link);
        if (r < 0)
                return log_netdev_error_errno(netdev, r, "Could not send rtnetlink message: %m");

        link_ref(link);

        log_netdev_debug(netdev, "Enslaving link '%s'", link->ifname);

        return 0;
}

static int netdev_enter_ready(NetDev *netdev) {
        netdev_join_callback *callback, *callback_next;
        int r;

        assert(netdev);
        assert(netdev->ifname);

        if (netdev->state != NETDEV_STATE_CREATING)
                return 0;

        netdev->state = NETDEV_STATE_READY;

        log_netdev_info(netdev, "netdev ready");

        LIST_FOREACH_SAFE(callbacks, callback, callback_next, netdev->callbacks) {
                /* enslave the links that were attempted to be enslaved before the
                 * link was ready */
                r = netdev_enslave_ready(netdev, callback->link, callback->callback);
                if (r < 0)
                        return r;

                LIST_REMOVE(callbacks, netdev->callbacks, callback);
                link_unref(callback->link);
                free(callback);
        }

        if (NETDEV_VTABLE(netdev)->post_create)
                NETDEV_VTABLE(netdev)->post_create(netdev, NULL, NULL);

        return 0;
}

/* callback for netdev's created without a backing Link */
static int netdev_create_handler(sd_netlink *rtnl, sd_netlink_message *m, NetDev *netdev) {
        int r;

        assert(netdev);
        assert(netdev->state != _NETDEV_STATE_INVALID);

        r = sd_netlink_message_get_errno(m);
        if (r == -EEXIST)
                log_netdev_info(netdev, "netdev exists, using existing without changing its parameters");
        else if (r < 0) {
                log_netdev_warning_errno(netdev, r, "netdev could not be created: %m");
                netdev_drop(netdev);

                return 1;
        }

        log_netdev_debug(netdev, "Created");

        return 1;
}

static int netdev_enslave(NetDev *netdev, Link *link, link_netlink_message_handler_t callback) {
        int r;

        assert(netdev);
        assert(netdev->manager);
        assert(netdev->manager->rtnl);
        assert(IN_SET(netdev->kind, NETDEV_KIND_BRIDGE, NETDEV_KIND_BOND, NETDEV_KIND_VRF, NETDEV_KIND_BATADV));

        if (netdev->state == NETDEV_STATE_READY) {
                r = netdev_enslave_ready(netdev, link, callback);
                if (r < 0)
                        return r;
        } else if (IN_SET(netdev->state, NETDEV_STATE_LINGER, NETDEV_STATE_FAILED)) {
                _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;

                r = rtnl_message_new_synthetic_error(netdev->manager->rtnl, -ENODEV, 0, &m);
                if (r >= 0)
                        callback(netdev->manager->rtnl, m, link);
        } else {
                /* the netdev is not yet ready, save this request for when it is */
                netdev_join_callback *cb;

                cb = new(netdev_join_callback, 1);
                if (!cb)
                        return log_oom();

                *cb = (netdev_join_callback) {
                        .callback = callback,
                        .link = link_ref(link),
                };

                LIST_PREPEND(callbacks, netdev->callbacks, cb);

                log_netdev_debug(netdev, "Will enslave '%s', when ready", link->ifname);
        }

        return 0;
}

int netdev_set_ifindex(NetDev *netdev, sd_netlink_message *message) {
        uint16_t type;
        const char *kind;
        const char *received_kind;
        const char *received_name;
        int r, ifindex;

        assert(netdev);
        assert(message);

        r = sd_netlink_message_get_type(message, &type);
        if (r < 0)
                return log_netdev_error_errno(netdev, r, "Could not get rtnl message type: %m");

        if (type != RTM_NEWLINK)
                return log_netdev_error_errno(netdev, SYNTHETIC_ERRNO(EINVAL), "Cannot set ifindex from unexpected rtnl message type.");

        r = sd_rtnl_message_link_get_ifindex(message, &ifindex);
        if (r < 0) {
                log_netdev_error_errno(netdev, r, "Could not get ifindex: %m");
                netdev_enter_failed(netdev);
                return r;
        } else if (ifindex <= 0) {
                log_netdev_error(netdev, "Got invalid ifindex: %d", ifindex);
                netdev_enter_failed(netdev);
                return -EINVAL;
        }

        if (netdev->ifindex > 0) {
                if (netdev->ifindex != ifindex) {
                        log_netdev_error(netdev, "Could not set ifindex to %d, already set to %d",
                                         ifindex, netdev->ifindex);
                        netdev_enter_failed(netdev);
                        return -EEXIST;
                } else
                        /* ifindex already set to the same for this netdev */
                        return 0;
        }

        r = sd_netlink_message_read_string(message, IFLA_IFNAME, &received_name);
        if (r < 0)
                return log_netdev_error_errno(netdev, r, "Could not get IFNAME: %m");

        if (!streq(netdev->ifname, received_name)) {
                log_netdev_error(netdev, "Received newlink with wrong IFNAME %s", received_name);
                netdev_enter_failed(netdev);
                return -EINVAL;
        }

        r = sd_netlink_message_enter_container(message, IFLA_LINKINFO);
        if (r < 0)
                return log_netdev_error_errno(netdev, r, "Could not get LINKINFO: %m");

        r = sd_netlink_message_read_string(message, IFLA_INFO_KIND, &received_kind);
        if (r < 0)
                return log_netdev_error_errno(netdev, r, "Could not get KIND: %m");

        r = sd_netlink_message_exit_container(message);
        if (r < 0)
                return log_netdev_error_errno(netdev, r, "Could not exit container: %m");

        if (netdev->kind == NETDEV_KIND_TAP)
                /* the kernel does not distinguish between tun and tap */
                kind = "tun";
        else {
                kind = netdev_kind_to_string(netdev->kind);
                if (!kind) {
                        log_netdev_error(netdev, "Could not get kind");
                        netdev_enter_failed(netdev);
                        return -EINVAL;
                }
        }

        if (!streq(kind, received_kind)) {
                log_netdev_error(netdev, "Received newlink with wrong KIND %s, expected %s",
                                 received_kind, kind);
                netdev_enter_failed(netdev);
                return -EINVAL;
        }

        netdev->ifindex = ifindex;

        log_netdev_debug(netdev, "netdev has index %d", netdev->ifindex);

        netdev_enter_ready(netdev);

        return 0;
}

#define HASH_KEY SD_ID128_MAKE(52,e1,45,bd,00,6f,29,96,21,c6,30,6d,83,71,04,48)

int netdev_get_mac(const char *ifname, struct ether_addr **ret) {
        _cleanup_free_ struct ether_addr *mac = NULL;
        uint64_t result;
        size_t l, sz;
        uint8_t *v;
        int r;

        assert(ifname);
        assert(ret);

        mac = new0(struct ether_addr, 1);
        if (!mac)
                return -ENOMEM;

        l = strlen(ifname);
        sz = sizeof(sd_id128_t) + l;
        v = newa(uint8_t, sz);

        /* fetch some persistent data unique to the machine */
        r = sd_id128_get_machine((sd_id128_t*) v);
        if (r < 0)
                return r;

        /* combine with some data unique (on this machine) to this
         * netdev */
        memcpy(v + sizeof(sd_id128_t), ifname, l);

        /* Let's hash the host machine ID plus the container name. We
         * use a fixed, but originally randomly created hash key here. */
        result = siphash24(v, sz, HASH_KEY.bytes);

        assert_cc(ETH_ALEN <= sizeof(result));
        memcpy(mac->ether_addr_octet, &result, ETH_ALEN);

        /* see eth_random_addr in the kernel */
        mac->ether_addr_octet[0] &= 0xfe;        /* clear multicast bit */
        mac->ether_addr_octet[0] |= 0x02;        /* set local assignment bit (IEEE802) */

        *ret = TAKE_PTR(mac);

        return 0;
}

static int netdev_create(NetDev *netdev, Link *link, link_netlink_message_handler_t callback) {
        int r;

        assert(netdev);
        assert(!link || callback);

        /* create netdev */
        if (NETDEV_VTABLE(netdev)->create) {
                assert(!link);

                r = NETDEV_VTABLE(netdev)->create(netdev);
                if (r < 0)
                        return r;

                log_netdev_debug(netdev, "Created");
        } else {
                _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;

                r = sd_rtnl_message_new_link(netdev->manager->rtnl, &m, RTM_NEWLINK, 0);
                if (r < 0)
                        return log_netdev_error_errno(netdev, r, "Could not allocate RTM_NEWLINK message: %m");

                r = sd_netlink_message_append_string(m, IFLA_IFNAME, netdev->ifname);
                if (r < 0)
                        return log_netdev_error_errno(netdev, r, "Could not append IFLA_IFNAME, attribute: %m");

                if (netdev->mac) {
                        r = sd_netlink_message_append_ether_addr(m, IFLA_ADDRESS, netdev->mac);
                        if (r < 0)
                                return log_netdev_error_errno(netdev, r, "Could not append IFLA_ADDRESS attribute: %m");
                }

                if (netdev->mtu != 0) {
                        r = sd_netlink_message_append_u32(m, IFLA_MTU, netdev->mtu);
                        if (r < 0)
                                return log_netdev_error_errno(netdev, r, "Could not append IFLA_MTU attribute: %m");
                }

                if (link) {
                        r = sd_netlink_message_append_u32(m, IFLA_LINK, link->ifindex);
                        if (r < 0)
                                return log_netdev_error_errno(netdev, r, "Could not append IFLA_LINK attribute: %m");
                }

                r = sd_netlink_message_open_container(m, IFLA_LINKINFO);
                if (r < 0)
                        return log_netdev_error_errno(netdev, r, "Could not append IFLA_LINKINFO attribute: %m");

                r = sd_netlink_message_open_container_union(m, IFLA_INFO_DATA, netdev_kind_to_string(netdev->kind));
                if (r < 0)
                        return log_netdev_error_errno(netdev, r, "Could not append IFLA_INFO_DATA attribute: %m");

                if (NETDEV_VTABLE(netdev)->fill_message_create) {
                        r = NETDEV_VTABLE(netdev)->fill_message_create(netdev, link, m);
                        if (r < 0)
                                return r;
                }

                r = sd_netlink_message_close_container(m);
                if (r < 0)
                        return log_netdev_error_errno(netdev, r, "Could not append IFLA_INFO_DATA attribute: %m");

                r = sd_netlink_message_close_container(m);
                if (r < 0)
                        return log_netdev_error_errno(netdev, r, "Could not append IFLA_LINKINFO attribute: %m");

                if (link) {
                        r = netlink_call_async(netdev->manager->rtnl, NULL, m, callback,
                                               link_netlink_destroy_callback, link);
                        if (r < 0)
                                return log_netdev_error_errno(netdev, r, "Could not send rtnetlink message: %m");

                        link_ref(link);
                } else {
                        r = netlink_call_async(netdev->manager->rtnl, NULL, m, netdev_create_handler,
                                               netdev_destroy_callback, netdev);
                        if (r < 0)
                                return log_netdev_error_errno(netdev, r, "Could not send rtnetlink message: %m");

                        netdev_ref(netdev);
                }

                netdev->state = NETDEV_STATE_CREATING;

                log_netdev_debug(netdev, "Creating");
        }

        return 0;
}

static int netdev_create_after_configured(NetDev *netdev, Link *link) {
        assert(netdev);
        assert(link);
        assert(NETDEV_VTABLE(netdev)->create_after_configured);

        return NETDEV_VTABLE(netdev)->create_after_configured(netdev, link);
}

/* the callback must be called, possibly after a timeout, as otherwise the Link will hang */
int netdev_join(NetDev *netdev, Link *link, link_netlink_message_handler_t callback) {
        int r;

        assert(netdev);
        assert(netdev->manager);
        assert(netdev->manager->rtnl);

        switch (netdev_get_create_type(netdev)) {
        case NETDEV_CREATE_MASTER:
                r = netdev_enslave(netdev, link, callback);
                if (r < 0)
                        return r;

                break;
        case NETDEV_CREATE_STACKED:
                r = netdev_create(netdev, link, callback);
                if (r < 0)
                        return r;

                break;
        case NETDEV_CREATE_AFTER_CONFIGURED:
                r = netdev_create_after_configured(netdev, link);
                if (r < 0)
                        return r;
                break;
        default:
                assert_not_reached("Cannot join independent netdev");
        }

        return 0;
}

static bool netdev_is_ready_to_create(NetDev *netdev, Link *link) {
        Request req;

        assert(netdev);
        assert(link);

        if (netdev->state != NETDEV_STATE_LOADING)
                return false;
        if (!IN_SET(link->state, LINK_STATE_INITIALIZED, LINK_STATE_CONFIGURING, LINK_STATE_CONFIGURED))
                return false;
        if (netdev_get_create_type(netdev) == NETDEV_CREATE_AFTER_CONFIGURED &&
            link->state != LINK_STATE_CONFIGURED)
                return false;

        req = (Request) {
                .link = link,
                .type = REQUEST_TYPE_SET_LINK,
                .set_link_operation = SET_LINK_MTU,
        };

        if (ordered_set_contains(link->manager->request_queue, &req))
                return false;

        return true;
}

int request_process_create_stacked_netdev(Request *req) {
        int r;

        assert(req);
        assert(req->link);
        assert(req->type == REQUEST_TYPE_CREATE_STACKED_NETDEV);
        assert(req->netdev);
        assert(req->netlink_handler);

        if (!netdev_is_ready_to_create(req->netdev, req->link))
                return 0;

        r = netdev_join(req->netdev, req->link, req->netlink_handler);
        if (r < 0)
                return log_link_error_errno(req->link, r, "Failed to create stacked netdev '%s': %m", req->netdev->ifname);

        return 1;
}

static int link_create_stacked_netdev_handler_internal(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
        int r;

        assert(m);
        assert(link);

        if (IN_SET(link->state, LINK_STATE_FAILED, LINK_STATE_LINGER))
                return 0;

        r = sd_netlink_message_get_errno(m);
        if (r < 0 && r != -EEXIST) {
                log_link_message_warning_errno(link, m, r, "Could not create stacked netdev");
                link_enter_failed(link);
                return 0;
        }

        return 1;
}

static int link_create_stacked_netdev_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
        assert(link);
        assert(link->create_stacked_netdev_messages > 0);

        link->create_stacked_netdev_messages--;

        if (link_create_stacked_netdev_handler_internal(rtnl, m, link) <= 0)
                return 0;

        if (link->create_stacked_netdev_messages == 0) {
                link->stacked_netdevs_created = true;
                log_link_debug(link, "Stacked netdevs created.");
        }

        return 0;
}

static int link_create_stacked_netdev_after_configured_handler(sd_netlink *rtnl, sd_netlink_message *m, Link *link) {
        assert(link);
        assert(link->create_stacked_netdev_after_configured_messages > 0);

        link->create_stacked_netdev_after_configured_messages--;

        if (link_create_stacked_netdev_handler_internal(rtnl, m, link) <= 0)
                return 0;

        if (link->create_stacked_netdev_after_configured_messages == 0) {
                link->stacked_netdevs_after_configured_created = true;
                log_link_debug(link, "Stacked netdevs created.");
        }

        return 0;
}

int link_request_to_crate_stacked_netdev(Link *link, NetDev *netdev) {
        NetDevCreateType create_type;
        int r;

        assert(link);
        assert(netdev);

        create_type = netdev_get_create_type(netdev);
        if (!IN_SET(create_type, NETDEV_CREATE_STACKED, NETDEV_CREATE_AFTER_CONFIGURED))
                return -EINVAL;

        if (netdev->state != NETDEV_STATE_LOADING || netdev->ifindex > 0)
                /* Already created (or removed?) */
                return 0;

        if (create_type == NETDEV_CREATE_STACKED) {
                link->stacked_netdevs_created = false;
                r = link_queue_request(link, REQUEST_TYPE_CREATE_STACKED_NETDEV, netdev, false,
                                       &link->create_stacked_netdev_messages,
                                       link_create_stacked_netdev_handler,
                                       NULL);
        } else {
                link->stacked_netdevs_after_configured_created = false;
                r = link_queue_request(link, REQUEST_TYPE_CREATE_STACKED_NETDEV, netdev, false,
                                       &link->create_stacked_netdev_after_configured_messages,
                                       link_create_stacked_netdev_after_configured_handler,
                                       NULL);
        }
        if (r < 0)
                return log_link_error_errno(link, r, "Failed to request to create stacked netdev '%s': %m",
                                            netdev->ifname);

        log_link_debug(link, "Requested to create stacked netdev '%s'", netdev->ifname);
        return 0;
}

int netdev_load_one(Manager *manager, const char *filename) {
        _cleanup_(netdev_unrefp) NetDev *netdev_raw = NULL, *netdev = NULL;
        const char *dropin_dirname;
        bool independent = false;
        int r;

        assert(manager);
        assert(filename);

        r = null_or_empty_path(filename);
        if (r == -ENOENT)
                return 0;
        if (r < 0)
                return r;
        if (r > 0) {
                log_debug("Skipping empty file: %s", filename);
                return 0;
        }

        netdev_raw = new(NetDev, 1);
        if (!netdev_raw)
                return log_oom();

        *netdev_raw = (NetDev) {
                .n_ref = 1,
                .kind = _NETDEV_KIND_INVALID,
                .state = _NETDEV_STATE_INVALID, /* an invalid state means done() of the implementation won't be called on destruction */
        };

        dropin_dirname = strjoina(basename(filename), ".d");
        r = config_parse_many(
                        STRV_MAKE_CONST(filename), NETWORK_DIRS, dropin_dirname,
                        NETDEV_COMMON_SECTIONS NETDEV_OTHER_SECTIONS,
                        config_item_perf_lookup, network_netdev_gperf_lookup,
                        CONFIG_PARSE_WARN,
                        netdev_raw,
                        NULL);
        if (r < 0)
                return r;

        /* skip out early if configuration does not match the environment */
        if (!condition_test_list(netdev_raw->conditions, environ, NULL, NULL, NULL)) {
                log_debug("%s: Conditions in the file do not match the system environment, skipping.", filename);
                return 0;
        }

        if (netdev_raw->kind == _NETDEV_KIND_INVALID) {
                log_warning("NetDev has no Kind= configured in %s. Ignoring", filename);
                return 0;
        }

        if (!netdev_raw->ifname) {
                log_warning("NetDev without Name= configured in %s. Ignoring", filename);
                return 0;
        }

        netdev = malloc0(NETDEV_VTABLE(netdev_raw)->object_size);
        if (!netdev)
                return log_oom();

        netdev->n_ref = 1;
        netdev->manager = manager;
        netdev->kind = netdev_raw->kind;
        netdev->state = NETDEV_STATE_LOADING; /* we initialize the state here for the first time,
                                                 so that done() will be called on destruction */

        if (NETDEV_VTABLE(netdev)->init)
                NETDEV_VTABLE(netdev)->init(netdev);

        r = config_parse_many(
                        STRV_MAKE_CONST(filename), NETWORK_DIRS, dropin_dirname,
                        NETDEV_VTABLE(netdev)->sections,
                        config_item_perf_lookup, network_netdev_gperf_lookup,
                        CONFIG_PARSE_WARN,
                        netdev, NULL);
        if (r < 0)
                return r;

        /* verify configuration */
        if (NETDEV_VTABLE(netdev)->config_verify) {
                r = NETDEV_VTABLE(netdev)->config_verify(netdev, filename);
                if (r < 0)
                        return 0;
        }

        netdev->filename = strdup(filename);
        if (!netdev->filename)
                return log_oom();

        if (!netdev->mac && NETDEV_VTABLE(netdev)->generate_mac) {
                r = netdev_get_mac(netdev->ifname, &netdev->mac);
                if (r < 0)
                        return log_netdev_error_errno(netdev, r,
                                                      "Failed to generate predictable MAC address: %m");
        }

        r = hashmap_ensure_put(&netdev->manager->netdevs, &string_hash_ops, netdev->ifname, netdev);
        if (r == -ENOMEM)
                return log_oom();
        if (r == -EEXIST) {
                NetDev *n = hashmap_get(netdev->manager->netdevs, netdev->ifname);

                assert(n);
                if (!streq(netdev->filename, n->filename))
                        log_netdev_warning_errno(netdev, r,
                                                 "Device was already configured by file %s, ignoring %s.",
                                                 n->filename, netdev->filename);

                /* Clear ifname before netdev_free() is called. Otherwise, the NetDev object 'n' is
                 * removed from the hashmap 'manager->netdevs'. */
                netdev->ifname = mfree(netdev->ifname);
                return 0;
        }
        if (r < 0)
                return r;

        LIST_HEAD_INIT(netdev->callbacks);

        log_netdev_debug(netdev, "loaded %s", netdev_kind_to_string(netdev->kind));

        if (IN_SET(netdev_get_create_type(netdev), NETDEV_CREATE_MASTER, NETDEV_CREATE_INDEPENDENT)) {
                r = netdev_create(netdev, NULL, NULL);
                if (r < 0)
                        return r;
        }

        switch (netdev->kind) {
        case NETDEV_KIND_IPIP:
                independent = IPIP(netdev)->independent;
                break;
        case NETDEV_KIND_GRE:
                independent = GRE(netdev)->independent;
                break;
        case NETDEV_KIND_GRETAP:
                independent = GRETAP(netdev)->independent;
                break;
        case NETDEV_KIND_IP6GRE:
                independent = IP6GRE(netdev)->independent;
                break;
        case NETDEV_KIND_IP6GRETAP:
                independent = IP6GRETAP(netdev)->independent;
                break;
        case NETDEV_KIND_SIT:
                independent = SIT(netdev)->independent;
                break;
        case NETDEV_KIND_VTI:
                independent = VTI(netdev)->independent;
                break;
        case NETDEV_KIND_VTI6:
                independent = VTI6(netdev)->independent;
                break;
        case NETDEV_KIND_IP6TNL:
                independent = IP6TNL(netdev)->independent;
                break;
        case NETDEV_KIND_ERSPAN:
                independent = ERSPAN(netdev)->independent;
                break;
        case NETDEV_KIND_XFRM:
                independent = XFRM(netdev)->independent;
                break;
        case NETDEV_KIND_VXLAN:
                independent = VXLAN(netdev)->independent;
                break;
        default:
                break;
        }

        if (independent) {
                r = netdev_create(netdev, NULL, NULL);
                if (r < 0)
                        return r;
        }

        netdev = NULL;

        return 0;
}

int netdev_load(Manager *manager, bool reload) {
        _cleanup_strv_free_ char **files = NULL;
        char **f;
        int r;

        assert(manager);

        if (!reload)
                hashmap_clear_with_destructor(manager->netdevs, netdev_unref);

        r = conf_files_list_strv(&files, ".netdev", NULL, 0, NETWORK_DIRS);
        if (r < 0)
                return log_error_errno(r, "Failed to enumerate netdev files: %m");

        STRV_FOREACH(f, files) {
                r = netdev_load_one(manager, *f);
                if (r < 0)
                        log_error_errno(r, "Failed to load %s, ignoring: %m", *f);
        }

        return 0;
}