Adding upstream version 252.22.upstream/252.22

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 880 insertions, 0 deletions

diff --git a/src/network/netdev/l2tp-tunnel.c b/src/network/netdev/l2tp-tunnel.c
new file mode 100644
index 0000000..fd2783e
--- /dev/null
+++ b/src/network/netdev/l2tp-tunnel.c
@@ -0,0 +1,880 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <netinet/in.h>
+#include <linux/l2tp.h>
+#include <linux/genetlink.h>
+
+#include "conf-parser.h"
+#include "hashmap.h"
+#include "l2tp-tunnel.h"
+#include "netlink-util.h"
+#include "networkd-address.h"
+#include "networkd-manager.h"
+#include "networkd-route-util.h"
+#include "parse-util.h"
+#include "socket-util.h"
+#include "string-table.h"
+#include "string-util.h"
+#include "util.h"
+
+static const char* const l2tp_l2spec_type_table[_NETDEV_L2TP_L2SPECTYPE_MAX] = {
+        [NETDEV_L2TP_L2SPECTYPE_NONE]    = "none",
+        [NETDEV_L2TP_L2SPECTYPE_DEFAULT] = "default",
+};
+
+DEFINE_PRIVATE_STRING_TABLE_LOOKUP_FROM_STRING(l2tp_l2spec_type, L2tpL2specType);
+
+static const char* const l2tp_encap_type_table[_NETDEV_L2TP_ENCAPTYPE_MAX] = {
+        [NETDEV_L2TP_ENCAPTYPE_UDP] = "udp",
+        [NETDEV_L2TP_ENCAPTYPE_IP]  = "ip",
+};
+
+DEFINE_PRIVATE_STRING_TABLE_LOOKUP_FROM_STRING(l2tp_encap_type, L2tpEncapType);
+DEFINE_CONFIG_PARSE_ENUM(config_parse_l2tp_encap_type, l2tp_encap_type, L2tpEncapType, "Failed to parse L2TP Encapsulation Type");
+
+static const char* const l2tp_local_address_type_table[_NETDEV_L2TP_LOCAL_ADDRESS_MAX] = {
+         [NETDEV_L2TP_LOCAL_ADDRESS_AUTO]    = "auto",
+         [NETDEV_L2TP_LOCAL_ADDRESS_STATIC]  = "static",
+         [NETDEV_L2TP_LOCAL_ADDRESS_DYNAMIC] = "dynamic",
+};
+
+DEFINE_PRIVATE_STRING_TABLE_LOOKUP_FROM_STRING(l2tp_local_address_type, L2tpLocalAddressType);
+
+static L2tpSession* l2tp_session_free(L2tpSession *s) {
+        if (!s)
+                return NULL;
+
+        if (s->tunnel && s->section)
+                ordered_hashmap_remove(s->tunnel->sessions_by_section, s->section);
+
+        config_section_free(s->section);
+        free(s->name);
+        return mfree(s);
+}
+
+DEFINE_SECTION_CLEANUP_FUNCTIONS(L2tpSession, l2tp_session_free);
+
+static int l2tp_session_new_static(L2tpTunnel *t, const char *filename, unsigned section_line, L2tpSession **ret) {
+        _cleanup_(config_section_freep) ConfigSection *n = NULL;
+        _cleanup_(l2tp_session_freep) L2tpSession *s = NULL;
+        int r;
+
+        assert(t);
+        assert(ret);
+        assert(filename);
+        assert(section_line > 0);
+
+        r = config_section_new(filename, section_line, &n);
+        if (r < 0)
+                return r;
+
+        s = ordered_hashmap_get(t->sessions_by_section, n);
+        if (s) {
+                *ret = TAKE_PTR(s);
+                return 0;
+        }
+
+        s = new(L2tpSession, 1);
+        if (!s)
+                return -ENOMEM;
+
+        *s = (L2tpSession) {
+                .l2tp_l2spec_type = NETDEV_L2TP_L2SPECTYPE_DEFAULT,
+                .tunnel = t,
+                .section = TAKE_PTR(n),
+        };
+
+        r = ordered_hashmap_ensure_put(&t->sessions_by_section, &config_section_hash_ops, s->section, s);
+        if (r < 0)
+                return r;
+
+        *ret = TAKE_PTR(s);
+        return 0;
+}
+
+static int netdev_l2tp_create_message_tunnel(NetDev *netdev, union in_addr_union *local_address, sd_netlink_message **ret) {
+        _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+        uint16_t encap_type;
+        L2tpTunnel *t;
+        int r;
+
+        assert(netdev);
+        assert(local_address);
+        assert_se(t = L2TP(netdev));
+
+        r = sd_genl_message_new(netdev->manager->genl, L2TP_GENL_NAME, L2TP_CMD_TUNNEL_CREATE, &m);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_append_u32(m, L2TP_ATTR_CONN_ID, t->tunnel_id);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_append_u32(m, L2TP_ATTR_PEER_CONN_ID, t->peer_tunnel_id);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_append_u8(m, L2TP_ATTR_PROTO_VERSION, 3);
+        if (r < 0)
+                return r;
+
+        switch (t->l2tp_encap_type) {
+        case NETDEV_L2TP_ENCAPTYPE_IP:
+                encap_type = L2TP_ENCAPTYPE_IP;
+                break;
+        case NETDEV_L2TP_ENCAPTYPE_UDP:
+        default:
+                encap_type = L2TP_ENCAPTYPE_UDP;
+                break;
+        }
+
+        r = sd_netlink_message_append_u16(m, L2TP_ATTR_ENCAP_TYPE, encap_type);
+        if (r < 0)
+                return r;
+
+        if (t->family == AF_INET) {
+                r = sd_netlink_message_append_in_addr(m, L2TP_ATTR_IP_SADDR, &local_address->in);
+                if (r < 0)
+                        return r;
+
+                r = sd_netlink_message_append_in_addr(m, L2TP_ATTR_IP_DADDR, &t->remote.in);
+                if (r < 0)
+                        return r;
+        } else {
+                r = sd_netlink_message_append_in6_addr(m, L2TP_ATTR_IP6_SADDR, &local_address->in6);
+                if (r < 0)
+                        return r;
+
+                r = sd_netlink_message_append_in6_addr(m, L2TP_ATTR_IP6_DADDR, &t->remote.in6);
+                if (r < 0)
+                        return r;
+        }
+
+        if (encap_type == L2TP_ENCAPTYPE_UDP) {
+                r = sd_netlink_message_append_u16(m, L2TP_ATTR_UDP_SPORT, t->l2tp_udp_sport);
+                if (r < 0)
+                        return r;
+
+                r = sd_netlink_message_append_u16(m, L2TP_ATTR_UDP_DPORT, t->l2tp_udp_dport);
+                if (r < 0)
+                        return r;
+
+                if (t->udp_csum) {
+                        r = sd_netlink_message_append_u8(m, L2TP_ATTR_UDP_CSUM, t->udp_csum);
+                        if (r < 0)
+                                return r;
+                }
+
+                if (t->udp6_csum_tx) {
+                        r = sd_netlink_message_append_flag(m, L2TP_ATTR_UDP_ZERO_CSUM6_TX);
+                        if (r < 0)
+                                return r;
+                }
+
+                if (t->udp6_csum_rx) {
+                        r = sd_netlink_message_append_flag(m, L2TP_ATTR_UDP_ZERO_CSUM6_RX);
+                        if (r < 0)
+                                return r;
+                }
+        }
+
+        *ret = TAKE_PTR(m);
+
+        return 0;
+}
+
+static int netdev_l2tp_create_message_session(NetDev *netdev, L2tpSession *session, sd_netlink_message **ret) {
+        _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+        uint16_t l2_spec_len;
+        uint8_t l2_spec_type;
+        int r;
+
+        assert(netdev);
+        assert(session);
+        assert(session->tunnel);
+
+        r = sd_genl_message_new(netdev->manager->genl, L2TP_GENL_NAME, L2TP_CMD_SESSION_CREATE, &m);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_append_u32(m, L2TP_ATTR_CONN_ID, session->tunnel->tunnel_id);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_append_u32(m, L2TP_ATTR_PEER_CONN_ID, session->tunnel->peer_tunnel_id);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_append_u32(m, L2TP_ATTR_SESSION_ID, session->session_id);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_append_u32(m, L2TP_ATTR_PEER_SESSION_ID, session->peer_session_id);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_append_u16(m, L2TP_ATTR_PW_TYPE, L2TP_PWTYPE_ETH);
+        if (r < 0)
+                return r;
+
+        switch (session->l2tp_l2spec_type) {
+        case NETDEV_L2TP_L2SPECTYPE_NONE:
+                l2_spec_type = L2TP_L2SPECTYPE_NONE;
+                l2_spec_len = 0;
+                break;
+        case NETDEV_L2TP_L2SPECTYPE_DEFAULT:
+        default:
+                l2_spec_type = L2TP_L2SPECTYPE_DEFAULT;
+                l2_spec_len = 4;
+                break;
+        }
+
+        r = sd_netlink_message_append_u8(m, L2TP_ATTR_L2SPEC_TYPE, l2_spec_type);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_append_u8(m, L2TP_ATTR_L2SPEC_LEN, l2_spec_len);
+        if (r < 0)
+                return r;
+
+        r = sd_netlink_message_append_string(m, L2TP_ATTR_IFNAME, session->name);
+        if (r < 0)
+                return r;
+
+        *ret = TAKE_PTR(m);
+
+        return 0;
+}
+
+static int link_get_l2tp_local_address(Link *link, L2tpTunnel *t, union in_addr_union *ret) {
+        Address *a;
+
+        assert(link);
+        assert(t);
+
+        SET_FOREACH(a, link->addresses) {
+                if (!address_is_ready(a))
+                        continue;
+
+                if (a->family != t->family)
+                        continue;
+
+                if (in_addr_is_set(a->family, &a->in_addr_peer))
+                        continue;
+
+                if (t->local_address_type == NETDEV_L2TP_LOCAL_ADDRESS_STATIC &&
+                    !FLAGS_SET(a->flags, IFA_F_PERMANENT))
+                        continue;
+
+                if (t->local_address_type == NETDEV_L2TP_LOCAL_ADDRESS_DYNAMIC &&
+                    FLAGS_SET(a->flags, IFA_F_PERMANENT))
+                        continue;
+
+                if (ret)
+                        *ret = a->in_addr;
+        }
+
+        return -ENOENT;
+}
+
+static int l2tp_get_local_address(NetDev *netdev, union in_addr_union *ret) {
+        Link *link = NULL;
+        L2tpTunnel *t;
+        Address *a = NULL;
+        int r;
+
+        assert(netdev);
+        assert(netdev->manager);
+        assert_se(t = L2TP(netdev));
+
+        if (t->local_ifname) {
+                r = link_get_by_name(netdev->manager, t->local_ifname, &link);
+                if (r < 0)
+                        return r;
+
+                if (!link_is_ready_to_configure(link, /* allow_unmanaged = */ false))
+                        return -EBUSY;
+        }
+
+        if (netdev->manager->manage_foreign_routes) {
+                /* First, check if the remote address is accessible. */
+                if (link)
+                        r = link_address_is_reachable(link, t->family, &t->remote, &t->local, &a);
+                else
+                        r = manager_address_is_reachable(netdev->manager, t->family, &t->remote, &t->local, &a);
+                if (r < 0)
+                        return r;
+        }
+
+        if (in_addr_is_set(t->family, &t->local)) {
+                /* local address is explicitly specified. */
+
+                if (!a) {
+                        if (link)
+                                r = link_get_address(link, t->family, &t->local, 0, &a);
+                        else
+                                r = manager_get_address(netdev->manager, t->family, &t->local, 0, &a);
+                        if (r < 0)
+                                return r;
+
+                        if (!address_is_ready(a))
+                                return -EBUSY;
+                }
+
+                if (ret)
+                        *ret = a->in_addr;
+
+                return 0;
+        }
+
+        if (a) {
+                if (t->local_address_type == NETDEV_L2TP_LOCAL_ADDRESS_STATIC &&
+                    !FLAGS_SET(a->flags, IFA_F_PERMANENT))
+                        return -EINVAL;
+
+                if (t->local_address_type == NETDEV_L2TP_LOCAL_ADDRESS_DYNAMIC &&
+                    FLAGS_SET(a->flags, IFA_F_PERMANENT))
+                        return -EINVAL;
+
+                if (ret)
+                        *ret = a->in_addr;
+
+                return 0;
+        }
+
+        if (link)
+                return link_get_l2tp_local_address(link, t, ret);
+
+        HASHMAP_FOREACH(link, netdev->manager->links_by_index) {
+                if (!link_is_ready_to_configure(link, /* allow_unmanaged = */ false))
+                        continue;
+
+                if (link_get_l2tp_local_address(link, t, ret) >= 0)
+                        return 0;
+        }
+
+        return -ENOENT;
+}
+
+static void l2tp_session_destroy_callback(L2tpSession *session) {
+        if (!session)
+                return;
+
+        netdev_unref(NETDEV(session->tunnel));
+}
+
+static int l2tp_create_session_handler(sd_netlink *rtnl, sd_netlink_message *m, L2tpSession *session) {
+        NetDev *netdev;
+        int r;
+
+        assert(session);
+        assert(session->tunnel);
+
+        netdev = NETDEV(session->tunnel);
+
+        r = sd_netlink_message_get_errno(m);
+        if (r == -EEXIST)
+                log_netdev_info(netdev, "L2TP session %s exists, using existing without changing its parameters",
+                                session->name);
+        else if (r < 0) {
+                log_netdev_warning_errno(netdev, r, "L2TP session %s could not be created: %m", session->name);
+                return 1;
+        }
+
+        log_netdev_debug(netdev, "L2TP session %s created", session->name);
+        return 1;
+}
+
+static int l2tp_create_session(NetDev *netdev, L2tpSession *session) {
+        _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *n = NULL;
+        int r;
+
+        r = netdev_l2tp_create_message_session(netdev, session, &n);
+        if (r < 0)
+                return log_netdev_error_errno(netdev, r, "Failed to create netlink message: %m");
+
+        r = netlink_call_async(netdev->manager->genl, NULL, n, l2tp_create_session_handler,
+                               l2tp_session_destroy_callback, session);
+        if (r < 0)
+                return log_netdev_error_errno(netdev, r, "Failed to create L2TP session %s: %m", session->name);
+
+        netdev_ref(netdev);
+        return 0;
+}
+
+static int l2tp_create_tunnel_handler(sd_netlink *rtnl, sd_netlink_message *m, NetDev *netdev) {
+        L2tpSession *session;
+        L2tpTunnel *t;
+        int r;
+
+        assert(netdev);
+        assert(netdev->state != _NETDEV_STATE_INVALID);
+
+        t = L2TP(netdev);
+
+        assert(t);
+
+        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_enter_failed(netdev);
+
+                return 1;
+        }
+
+        log_netdev_debug(netdev, "L2TP tunnel is created");
+
+        ORDERED_HASHMAP_FOREACH(session, t->sessions_by_section)
+                (void) l2tp_create_session(netdev, session);
+
+        return 1;
+}
+
+static int l2tp_create_tunnel(NetDev *netdev) {
+        _cleanup_(sd_netlink_message_unrefp) sd_netlink_message *m = NULL;
+        union in_addr_union local_address;
+        L2tpTunnel *t;
+        int r;
+
+        assert(netdev);
+        assert_se(t = L2TP(netdev));
+
+        r = l2tp_get_local_address(netdev, &local_address);
+        if (r < 0)
+                return log_netdev_error_errno(netdev, r, "Could not find local address.");
+
+        if (t->local_address_type >= 0 && DEBUG_LOGGING)
+                log_netdev_debug(netdev, "Local address %s acquired.",
+                                 IN_ADDR_TO_STRING(t->family, &local_address));
+
+        r = netdev_l2tp_create_message_tunnel(netdev, &local_address, &m);
+        if (r < 0)
+                return log_netdev_error_errno(netdev, r, "Failed to create netlink message: %m");
+
+        r = netlink_call_async(netdev->manager->genl, NULL, m, l2tp_create_tunnel_handler,
+                               netdev_destroy_callback, netdev);
+        if (r < 0)
+                return log_netdev_error_errno(netdev, r, "Failed to create L2TP tunnel: %m");
+
+        netdev_ref(netdev);
+
+        return 0;
+}
+
+static int netdev_l2tp_is_ready_to_create(NetDev *netdev, Link *link) {
+        return l2tp_get_local_address(netdev, NULL) >= 0;
+}
+
+int config_parse_l2tp_tunnel_local_address(
+                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) {
+
+        _cleanup_free_ char *addr_or_type = NULL, *ifname = NULL;
+        L2tpLocalAddressType type;
+        L2tpTunnel *t = ASSERT_PTR(userdata);
+        const char *p = ASSERT_PTR(rvalue);
+        union in_addr_union a;
+        int r, f;
+
+        assert(filename);
+        assert(lvalue);
+
+        if (isempty(rvalue)) {
+                t->local_ifname = mfree(t->local_ifname);
+                t->local_address_type = NETDEV_L2TP_LOCAL_ADDRESS_AUTO;
+                t->local = IN_ADDR_NULL;
+
+                if (!in_addr_is_set(t->family, &t->remote))
+                        /* If Remote= is not specified yet, then also clear family. */
+                        t->family = AF_UNSPEC;
+
+                return 0;
+        }
+
+        r = extract_first_word(&p, &addr_or_type, "@", 0);
+        if (r < 0)
+                return log_oom();
+        if (r == 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Invalid L2TP Tunnel address specified in %s=, ignoring assignment: %s", lvalue, rvalue);
+                return 0;
+        }
+
+        if (!isempty(p)) {
+                if (!ifname_valid_full(p, IFNAME_VALID_ALTERNATIVE)) {
+                        log_syntax(unit, LOG_WARNING, filename, line, 0,
+                                   "Invalid interface name specified in %s=, ignoring assignment: %s", lvalue, rvalue);
+                        return 0;
+                }
+
+                ifname = strdup(p);
+                if (!ifname)
+                        return log_oom();
+        }
+
+        type = l2tp_local_address_type_from_string(addr_or_type);
+        if (type >= 0) {
+                free_and_replace(t->local_ifname, ifname);
+                t->local_address_type = type;
+                t->local = IN_ADDR_NULL;
+
+                if (!in_addr_is_set(t->family, &t->remote))
+                        /* If Remote= is not specified yet, then also clear family. */
+                        t->family = AF_UNSPEC;
+
+                return 0;
+        }
+
+        r = in_addr_from_string_auto(addr_or_type, &f, &a);
+        if (r < 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, r,
+                           "Invalid L2TP Tunnel local address \"%s\" specified, ignoring assignment: %s", addr_or_type, rvalue);
+                return 0;
+        }
+
+        if (in_addr_is_null(f, &a)) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "L2TP Tunnel local address cannot be null, ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        if (t->family != AF_UNSPEC && t->family != f) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Address family does not match the previous assignment, ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        t->family = f;
+        t->local = a;
+        free_and_replace(t->local_ifname, ifname);
+        t->local_address_type = _NETDEV_L2TP_LOCAL_ADDRESS_INVALID;
+        return 0;
+}
+
+int config_parse_l2tp_tunnel_remote_address(
+                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) {
+
+        L2tpTunnel *t = ASSERT_PTR(userdata);
+        union in_addr_union a;
+        int r, f;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+
+        if (isempty(rvalue)) {
+                t->remote = IN_ADDR_NULL;
+
+                if (!in_addr_is_set(t->family, &t->local))
+                        /* If Local= is not specified yet, then also clear family. */
+                        t->family = AF_UNSPEC;
+
+                return 0;
+        }
+
+        r = in_addr_from_string_auto(rvalue, &f, &a);
+        if (r < 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, r,
+                           "Invalid L2TP Tunnel remote address specified, ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        if (in_addr_is_null(f, &a)) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "L2TP Tunnel remote address cannot be null, ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        if (t->family != AF_UNSPEC && t->family != f) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Address family does not match the previous assignment, ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        t->family = f;
+        t->remote = a;
+        return 0;
+}
+
+int config_parse_l2tp_tunnel_id(
+                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) {
+
+        uint32_t *id = data, k;
+        int r;
+
+        assert(filename);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = safe_atou32(rvalue, &k);
+        if (r < 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, r,
+                           "Failed to parse L2TP tunnel id. Ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        if (k == 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Invalid L2TP tunnel id. Ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        *id = k;
+
+        return 0;
+}
+
+int config_parse_l2tp_session_id(
+                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) {
+
+        _cleanup_(l2tp_session_free_or_set_invalidp) L2tpSession *session = NULL;
+        L2tpTunnel *t = userdata;
+        uint32_t k;
+        int r;
+
+        assert(filename);
+        assert(section);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = l2tp_session_new_static(t, filename, section_line, &session);
+        if (r < 0)
+                return log_oom();
+
+        r = safe_atou32(rvalue, &k);
+        if (r < 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, r,
+                           "Failed to parse L2TP session id. Ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        if (k == 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Invalid L2TP session id. Ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        if (streq(lvalue, "SessionId"))
+                session->session_id = k;
+        else
+                session->peer_session_id = k;
+
+        session = NULL;
+        return 0;
+}
+
+int config_parse_l2tp_session_l2spec(
+                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) {
+
+        _cleanup_(l2tp_session_free_or_set_invalidp) L2tpSession *session = NULL;
+        L2tpTunnel *t = userdata;
+        L2tpL2specType spec;
+        int r;
+
+        assert(filename);
+        assert(section);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = l2tp_session_new_static(t, filename, section_line, &session);
+        if (r < 0)
+                return log_oom();
+
+        spec = l2tp_l2spec_type_from_string(rvalue);
+        if (spec < 0) {
+                log_syntax(unit, LOG_WARNING, filename, line, spec,
+                           "Failed to parse layer2 specific header type. Ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        session->l2tp_l2spec_type = spec;
+
+        session = NULL;
+        return 0;
+}
+
+int config_parse_l2tp_session_name(
+                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) {
+
+        _cleanup_(l2tp_session_free_or_set_invalidp) L2tpSession *session = NULL;
+        L2tpTunnel *t = userdata;
+        int r;
+
+        assert(filename);
+        assert(section);
+        assert(lvalue);
+        assert(rvalue);
+        assert(data);
+
+        r = l2tp_session_new_static(t, filename, section_line, &session);
+        if (r < 0)
+                return log_oom();
+
+        if (!ifname_valid(rvalue)) {
+                log_syntax(unit, LOG_WARNING, filename, line, 0,
+                           "Failed to parse L2TP tunnel session name. Ignoring assignment: %s", rvalue);
+                return 0;
+        }
+
+        r = free_and_strdup(&session->name, rvalue);
+        if (r < 0)
+                return log_oom();
+
+        session = NULL;
+        return 0;
+}
+
+static void l2tp_tunnel_init(NetDev *netdev) {
+        L2tpTunnel *t;
+
+        assert(netdev);
+
+        t = L2TP(netdev);
+
+        assert(t);
+
+        t->l2tp_encap_type = NETDEV_L2TP_ENCAPTYPE_UDP;
+        t->udp6_csum_rx = true;
+        t->udp6_csum_tx = true;
+}
+
+static int l2tp_session_verify(L2tpSession *session) {
+        NetDev *netdev;
+
+        assert(session);
+        assert(session->tunnel);
+
+        netdev = NETDEV(session->tunnel);
+
+        if (section_is_invalid(session->section))
+                return -EINVAL;
+
+        if (!session->name)
+                return log_netdev_error_errno(netdev, SYNTHETIC_ERRNO(EINVAL),
+                                              "%s: L2TP session without name configured. "
+                                              "Ignoring [L2TPSession] section from line %u",
+                                              session->section->filename, session->section->line);
+
+        if (session->session_id == 0 || session->peer_session_id == 0)
+                return log_netdev_error_errno(netdev, SYNTHETIC_ERRNO(EINVAL),
+                                              "%s: L2TP session without session IDs configured. "
+                                              "Ignoring [L2TPSession] section from line %u",
+                                              session->section->filename, session->section->line);
+
+        return 0;
+}
+
+static int netdev_l2tp_tunnel_verify(NetDev *netdev, const char *filename) {
+        L2tpTunnel *t;
+        L2tpSession *session;
+
+        assert(netdev);
+        assert(filename);
+
+        t = L2TP(netdev);
+
+        assert(t);
+
+        if (!IN_SET(t->family, AF_INET, AF_INET6))
+                return log_netdev_error_errno(netdev, SYNTHETIC_ERRNO(EINVAL),
+                                              "%s: L2TP tunnel with invalid address family configured. Ignoring",
+                                              filename);
+
+        if (!in_addr_is_set(t->family, &t->remote))
+                return log_netdev_error_errno(netdev, SYNTHETIC_ERRNO(EINVAL),
+                                              "%s: L2TP tunnel without a remote address configured. Ignoring",
+                                              filename);
+
+        if (t->tunnel_id == 0 || t->peer_tunnel_id == 0)
+                return log_netdev_error_errno(netdev, SYNTHETIC_ERRNO(EINVAL),
+                                              "%s: L2TP tunnel without tunnel IDs configured. Ignoring",
+                                              filename);
+
+        ORDERED_HASHMAP_FOREACH(session, t->sessions_by_section)
+                if (l2tp_session_verify(session) < 0)
+                        l2tp_session_free(session);
+
+        return 0;
+}
+
+static void l2tp_tunnel_done(NetDev *netdev) {
+        L2tpTunnel *t;
+
+        assert(netdev);
+
+        t = L2TP(netdev);
+
+        assert(t);
+
+        ordered_hashmap_free_with_destructor(t->sessions_by_section, l2tp_session_free);
+        free(t->local_ifname);
+}
+
+const NetDevVTable l2tptnl_vtable = {
+        .object_size = sizeof(L2tpTunnel),
+        .init = l2tp_tunnel_init,
+        .sections = NETDEV_COMMON_SECTIONS "L2TP\0L2TPSession\0",
+        .create = l2tp_create_tunnel,
+        .done = l2tp_tunnel_done,
+        .create_type = NETDEV_CREATE_INDEPENDENT,
+        .is_ready_to_create = netdev_l2tp_is_ready_to_create,
+        .config_verify = netdev_l2tp_tunnel_verify,
+};