]> git.ipfire.org Git - thirdparty/systemd.git/blobdiff - src/resolve/resolved-link.c
tree-wide: use mfree more
[thirdparty/systemd.git] / src / resolve / resolved-link.c
index 8785079de86868a9bf1212372e2343002d73b994..13e1f91192ecdf2797ea69ee6e9bceba3b333160 100644 (file)
@@ -1,5 +1,3 @@
-/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
-
 /***
   This file is part of systemd.
 
 #include "sd-network.h"
 
 #include "alloc-util.h"
+#include "fd-util.h"
+#include "fileio.h"
 #include "missing.h"
+#include "mkdir.h"
 #include "parse-util.h"
 #include "resolved-link.h"
 #include "string-util.h"
@@ -47,6 +48,12 @@ int link_new(Manager *m, Link **ret, int ifindex) {
 
         l->ifindex = ifindex;
         l->llmnr_support = RESOLVE_SUPPORT_YES;
+        l->mdns_support = RESOLVE_SUPPORT_NO;
+        l->dnssec_mode = _DNSSEC_MODE_INVALID;
+        l->operstate = IF_OPER_UNKNOWN;
+
+        if (asprintf(&l->state_file, "/run/systemd/resolve/netif/%i", ifindex) < 0)
+                return -ENOMEM;
 
         r = hashmap_put(m->links, INT_TO_PTR(ifindex), l);
         if (r < 0)
@@ -61,15 +68,27 @@ int link_new(Manager *m, Link **ret, int ifindex) {
         return 0;
 }
 
+void link_flush_settings(Link *l) {
+        assert(l);
+
+        l->llmnr_support = RESOLVE_SUPPORT_YES;
+        l->mdns_support = RESOLVE_SUPPORT_NO;
+        l->dnssec_mode = _DNSSEC_MODE_INVALID;
+
+        dns_server_unlink_all(l->dns_servers);
+        dns_search_domain_unlink_all(l->search_domains);
+
+        l->dnssec_negative_trust_anchors = set_free_free(l->dnssec_negative_trust_anchors);
+}
+
 Link *link_free(Link *l) {
         if (!l)
                 return NULL;
 
-        dns_server_unlink_all(l->dns_servers);
-        dns_search_domain_unlink_all(l->search_domains);
+        link_flush_settings(l);
 
         while (l->addresses)
-                link_address_free(l->addresses);
+                (void) link_address_free(l->addresses);
 
         if (l->manager)
                 hashmap_remove(l->manager->links, INT_TO_PTR(l->ifindex));
@@ -80,16 +99,18 @@ Link *link_free(Link *l) {
         dns_scope_free(l->mdns_ipv4_scope);
         dns_scope_free(l->mdns_ipv6_scope);
 
-        free(l);
-        return NULL;
+        free(l->state_file);
+
+        return mfree(l);
 }
 
-static void link_allocate_scopes(Link *l) {
+void link_allocate_scopes(Link *l) {
         int r;
 
         assert(l);
 
-        if (l->dns_servers) {
+        if (link_relevant(l, AF_UNSPEC, false) &&
+            l->dns_servers) {
                 if (!l->unicast_scope) {
                         r = dns_scope_new(l->manager, &l->unicast_scope, l, DNS_PROTOCOL_DNS, AF_UNSPEC);
                         if (r < 0)
@@ -98,7 +119,7 @@ static void link_allocate_scopes(Link *l) {
         } else
                 l->unicast_scope = dns_scope_free(l->unicast_scope);
 
-        if (link_relevant(l, AF_INET) &&
+        if (link_relevant(l, AF_INET, true) &&
             l->llmnr_support != RESOLVE_SUPPORT_NO &&
             l->manager->llmnr_support != RESOLVE_SUPPORT_NO) {
                 if (!l->llmnr_ipv4_scope) {
@@ -109,7 +130,7 @@ static void link_allocate_scopes(Link *l) {
         } else
                 l->llmnr_ipv4_scope = dns_scope_free(l->llmnr_ipv4_scope);
 
-        if (link_relevant(l, AF_INET6) &&
+        if (link_relevant(l, AF_INET6, true) &&
             l->llmnr_support != RESOLVE_SUPPORT_NO &&
             l->manager->llmnr_support != RESOLVE_SUPPORT_NO &&
             socket_ipv6_is_supported()) {
@@ -121,7 +142,7 @@ static void link_allocate_scopes(Link *l) {
         } else
                 l->llmnr_ipv6_scope = dns_scope_free(l->llmnr_ipv6_scope);
 
-        if (link_relevant(l, AF_INET) &&
+        if (link_relevant(l, AF_INET, true) &&
             l->mdns_support != RESOLVE_SUPPORT_NO &&
             l->manager->mdns_support != RESOLVE_SUPPORT_NO) {
                 if (!l->mdns_ipv4_scope) {
@@ -132,7 +153,7 @@ static void link_allocate_scopes(Link *l) {
         } else
                 l->mdns_ipv4_scope = dns_scope_free(l->mdns_ipv4_scope);
 
-        if (link_relevant(l, AF_INET6) &&
+        if (link_relevant(l, AF_INET6, true) &&
             l->mdns_support != RESOLVE_SUPPORT_NO &&
             l->manager->mdns_support != RESOLVE_SUPPORT_NO) {
                 if (!l->mdns_ipv6_scope) {
@@ -151,7 +172,7 @@ void link_add_rrs(Link *l, bool force_remove) {
                 link_address_add_rrs(a, force_remove);
 }
 
-int link_update_rtnl(Link *l, sd_netlink_message *m) {
+int link_process_rtnl(Link *l, sd_netlink_message *m) {
         const char *n = NULL;
         int r;
 
@@ -162,7 +183,8 @@ int link_update_rtnl(Link *l, sd_netlink_message *m) {
         if (r < 0)
                 return r;
 
-        sd_netlink_message_read_u32(m, IFLA_MTU, &l->mtu);
+        (void) sd_netlink_message_read_u32(m, IFLA_MTU, &l->mtu);
+        (void) sd_netlink_message_read_u8(m, IFLA_OPERSTATE, &l->operstate);
 
         if (sd_netlink_message_read_string(m, IFLA_IFNAME, &n) >= 0) {
                 strncpy(l->name, n, sizeof(l->name)-1);
@@ -175,6 +197,27 @@ int link_update_rtnl(Link *l, sd_netlink_message *m) {
         return 0;
 }
 
+static int link_update_dns_server_one(Link *l, const char *name) {
+        union in_addr_union a;
+        DnsServer *s;
+        int family, r;
+
+        assert(l);
+        assert(name);
+
+        r = in_addr_from_string_auto(name, &family, &a);
+        if (r < 0)
+                return r;
+
+        s = dns_server_find(l->dns_servers, family, &a, 0);
+        if (s) {
+                dns_server_move_back_and_unmark(s);
+                return 0;
+        }
+
+        return dns_server_new(l->manager, NULL, DNS_SERVER_LINK, l, family, &a, 0);
+}
+
 static int link_update_dns_servers(Link *l) {
         _cleanup_strv_free_ char **nameservers = NULL;
         char **nameserver;
@@ -193,22 +236,9 @@ static int link_update_dns_servers(Link *l) {
         dns_server_mark_all(l->dns_servers);
 
         STRV_FOREACH(nameserver, nameservers) {
-                union in_addr_union a;
-                DnsServer *s;
-                int family;
-
-                r = in_addr_from_string_auto(*nameserver, &family, &a);
+                r = link_update_dns_server_one(l, *nameserver);
                 if (r < 0)
                         goto clear;
-
-                s = dns_server_find(l->dns_servers, family, &a);
-                if (s)
-                        dns_server_move_back_and_unmark(s);
-                else {
-                        r = dns_server_new(l->manager, NULL, DNS_SERVER_LINK, l, family, &a);
-                        if (r < 0)
-                                goto clear;
-                }
         }
 
         dns_server_unlink_marked(l->dns_servers);
@@ -273,38 +303,147 @@ clear:
         return r;
 }
 
-static int link_update_search_domains(Link *l) {
-        _cleanup_strv_free_ char **domains = NULL;
-        char **i;
+void link_set_dnssec_mode(Link *l, DnssecMode mode) {
+
+        assert(l);
+
+        if (l->dnssec_mode == mode)
+                return;
+
+        if ((l->dnssec_mode == _DNSSEC_MODE_INVALID) ||
+            (l->dnssec_mode == DNSSEC_NO && mode != DNSSEC_NO) ||
+            (l->dnssec_mode == DNSSEC_ALLOW_DOWNGRADE && mode == DNSSEC_YES)) {
+
+                /* When switching from non-DNSSEC mode to DNSSEC mode, flush the cache. Also when switching from the
+                 * allow-downgrade mode to full DNSSEC mode, flush it too. */
+                if (l->unicast_scope)
+                        dns_cache_flush(&l->unicast_scope->cache);
+        }
+
+        l->dnssec_mode = mode;
+}
+
+static int link_update_dnssec_mode(Link *l) {
+        _cleanup_free_ char *m = NULL;
+        DnssecMode mode;
         int r;
 
         assert(l);
 
-        r = sd_network_link_get_domains(l->ifindex, &domains);
+        r = sd_network_link_get_dnssec(l->ifindex, &m);
         if (r == -ENODATA) {
-                /* networkd knows nothing about this interface, and that's fine. */
                 r = 0;
                 goto clear;
         }
         if (r < 0)
                 goto clear;
 
-        dns_search_domain_mark_all(l->search_domains);
+        mode = dnssec_mode_from_string(m);
+        if (mode < 0) {
+                r = -EINVAL;
+                goto clear;
+        }
+
+        link_set_dnssec_mode(l, mode);
+
+        return 0;
+
+clear:
+        l->dnssec_mode = _DNSSEC_MODE_INVALID;
+        return r;
+}
+
+static int link_update_dnssec_negative_trust_anchors(Link *l) {
+        _cleanup_strv_free_ char **ntas = NULL;
+        _cleanup_set_free_free_ Set *ns = NULL;
+        int r;
+
+        assert(l);
+
+        r = sd_network_link_get_dnssec_negative_trust_anchors(l->ifindex, &ntas);
+        if (r == -ENODATA) {
+                r = 0;
+                goto clear;
+        }
+        if (r < 0)
+                goto clear;
+
+        ns = set_new(&dns_name_hash_ops);
+        if (!ns)
+                return -ENOMEM;
+
+        r = set_put_strdupv(ns, ntas);
+        if (r < 0)
+                return r;
+
+        set_free_free(l->dnssec_negative_trust_anchors);
+        l->dnssec_negative_trust_anchors = ns;
+        ns = NULL;
+
+        return 0;
+
+clear:
+        l->dnssec_negative_trust_anchors = set_free_free(l->dnssec_negative_trust_anchors);
+        return r;
+}
+
+static int link_update_search_domain_one(Link *l, const char *name, bool route_only) {
+        DnsSearchDomain *d;
+        int r;
+
+        assert(l);
+        assert(name);
+
+        r = dns_search_domain_find(l->search_domains, name, &d);
+        if (r < 0)
+                return r;
+        if (r > 0)
+                dns_search_domain_move_back_and_unmark(d);
+        else {
+                r = dns_search_domain_new(l->manager, &d, DNS_SEARCH_DOMAIN_LINK, l, name);
+                if (r < 0)
+                        return r;
+        }
+
+        d->route_only = route_only;
+        return 0;
+}
+
+static int link_update_search_domains(Link *l) {
+        _cleanup_strv_free_ char **sdomains = NULL, **rdomains = NULL;
+        char **i;
+        int r, q;
+
+        assert(l);
+
+        r = sd_network_link_get_search_domains(l->ifindex, &sdomains);
+        if (r < 0 && r != -ENODATA)
+                goto clear;
 
-        STRV_FOREACH(i, domains) {
-                DnsSearchDomain *d;
+        q = sd_network_link_get_route_domains(l->ifindex, &rdomains);
+        if (q < 0 && q != -ENODATA) {
+                r = q;
+                goto clear;
+        }
 
-                r = dns_search_domain_find(l->search_domains, *i, &d);
+        if (r == -ENODATA && q == -ENODATA) {
+                /* networkd knows nothing about this interface, and that's fine. */
+                r = 0;
+                goto clear;
+        }
+
+        dns_search_domain_mark_all(l->search_domains);
+
+        STRV_FOREACH(i, sdomains) {
+                r = link_update_search_domain_one(l, *i, false);
                 if (r < 0)
                         goto clear;
+        }
 
-                if (r > 0)
-                        dns_search_domain_move_back_and_unmark(d);
-                else {
-                        r = dns_search_domain_new(l->manager, NULL, DNS_SEARCH_DOMAIN_LINK, l, *i);
-                        if (r < 0)
-                                goto clear;
-                }
+        STRV_FOREACH(i, rdomains) {
+                r = link_update_search_domain_one(l, *i, true);
+                if (r < 0)
+                        goto clear;
         }
 
         dns_search_domain_unlink_marked(l->search_domains);
@@ -315,11 +454,45 @@ clear:
         return r;
 }
 
-int link_update_monitor(Link *l) {
+static int link_is_managed(Link *l) {
+        _cleanup_free_ char *state = NULL;
         int r;
 
         assert(l);
 
+        r = sd_network_link_get_setup_state(l->ifindex, &state);
+        if (r == -ENODATA)
+                return 0;
+        if (r < 0)
+                return r;
+
+        return !STR_IN_SET(state, "pending", "unmanaged");
+}
+
+static void link_read_settings(Link *l) {
+        int r;
+
+        assert(l);
+
+        /* Read settings from networkd, except when networkd is not managing this interface. */
+
+        r = link_is_managed(l);
+        if (r < 0) {
+                log_warning_errno(r, "Failed to determine whether interface %s is managed: %m", l->name);
+                return;
+        }
+        if (r == 0) {
+
+                /* If this link used to be managed, but is now unmanaged, flush all our settings — but only once. */
+                if (l->is_managed)
+                        link_flush_settings(l);
+
+                l->is_managed = false;
+                return;
+        }
+
+        l->is_managed = true;
+
         r = link_update_dns_servers(l);
         if (r < 0)
                 log_warning_errno(r, "Failed to read DNS servers for interface %s, ignoring: %m", l->name);
@@ -332,39 +505,67 @@ int link_update_monitor(Link *l) {
         if (r < 0)
                 log_warning_errno(r, "Failed to read mDNS support for interface %s, ignoring: %m", l->name);
 
-        link_allocate_scopes(l);
+        r = link_update_dnssec_mode(l);
+        if (r < 0)
+                log_warning_errno(r, "Failed to read DNSSEC mode for interface %s, ignoring: %m", l->name);
+
+        r = link_update_dnssec_negative_trust_anchors(l);
+        if (r < 0)
+                log_warning_errno(r, "Failed to read DNSSEC negative trust anchors for interface %s, ignoring: %m", l->name);
 
         r = link_update_search_domains(l);
         if (r < 0)
                 log_warning_errno(r, "Failed to read search domains for interface %s, ignoring: %m", l->name);
+}
+
+int link_update(Link *l) {
+        assert(l);
 
+        link_read_settings(l);
+        link_load_user(l);
+        link_allocate_scopes(l);
         link_add_rrs(l, false);
 
         return 0;
 }
 
-bool link_relevant(Link *l, int family) {
+bool link_relevant(Link *l, int family, bool local_multicast) {
         _cleanup_free_ char *state = NULL;
         LinkAddress *a;
 
         assert(l);
 
-        /* A link is relevant if it isn't a loopback or pointopoint
-         * device, has a link beat, can do multicast and has at least
-         * one relevant IP address */
+        /* A link is relevant for local multicast traffic if it isn't a loopback or pointopoint device, has a link
+         * beat, can do multicast and has at least one link-local (or better) IP address.
+         *
+         * A link is relevant for non-multicast traffic if it isn't a loopback device, has a link beat, and has at
+         * least one routable address.*/
 
-        if (l->flags & (IFF_LOOPBACK|IFF_POINTOPOINT|IFF_DORMANT))
+        if (l->flags & (IFF_LOOPBACK|IFF_DORMANT))
                 return false;
 
-        if ((l->flags & (IFF_UP|IFF_LOWER_UP|IFF_MULTICAST)) != (IFF_UP|IFF_LOWER_UP|IFF_MULTICAST))
+        if ((l->flags & (IFF_UP|IFF_LOWER_UP)) != (IFF_UP|IFF_LOWER_UP))
                 return false;
 
-        sd_network_link_get_operational_state(l->ifindex, &state);
+        if (local_multicast) {
+                if (l->flags & IFF_POINTOPOINT)
+                        return false;
+
+                if ((l->flags & IFF_MULTICAST) != IFF_MULTICAST)
+                        return false;
+        }
+
+        /* Check kernel operstate
+         * https://www.kernel.org/doc/Documentation/networking/operstates.txt */
+        if (!IN_SET(l->operstate, IF_OPER_UNKNOWN, IF_OPER_UP))
+                return false;
+
+        (void) sd_network_link_get_operational_state(l->ifindex, &state);
         if (state && !STR_IN_SET(state, "unknown", "degraded", "routable"))
                 return false;
 
         LIST_FOREACH(addresses, a, l->addresses)
-                if (a->family == family && link_address_relevant(a))
+                if ((family == AF_UNSPEC || a->family == family) && link_address_relevant(a, local_multicast))
                         return true;
 
         return false;
@@ -388,12 +589,8 @@ DnsServer* link_set_dns_server(Link *l, DnsServer *s) {
         if (l->current_dns_server == s)
                 return s;
 
-        if (s) {
-                _cleanup_free_ char *ip = NULL;
-
-                in_addr_to_string(s->family, &s->address, &ip);
-                log_info("Switching to DNS server %s for interface %s.", strna(ip), l->name);
-        }
+        if (s)
+                log_info("Switching to DNS server %s for interface %s.", dns_server_string(s), l->name);
 
         dns_server_unref(l->current_dns_server);
         l->current_dns_server = dns_server_ref(s);
@@ -429,6 +626,30 @@ void link_next_dns_server(Link *l) {
         link_set_dns_server(l, l->dns_servers);
 }
 
+DnssecMode link_get_dnssec_mode(Link *l) {
+        assert(l);
+
+        if (l->dnssec_mode != _DNSSEC_MODE_INVALID)
+                return l->dnssec_mode;
+
+        return manager_get_dnssec_mode(l->manager);
+}
+
+bool link_dnssec_supported(Link *l) {
+        DnsServer *server;
+
+        assert(l);
+
+        if (link_get_dnssec_mode(l) == DNSSEC_NO)
+                return false;
+
+        server = link_get_dns_server(l);
+        if (server)
+                return dns_server_dnssec_supported(server);
+
+        return true;
+}
+
 int link_address_new(Link *l, LinkAddress **ret, int family, const union in_addr_union *in_addr) {
         LinkAddress *a;
 
@@ -476,8 +697,7 @@ LinkAddress *link_address_free(LinkAddress *a) {
         dns_resource_record_unref(a->llmnr_address_rr);
         dns_resource_record_unref(a->llmnr_ptr_rr);
 
-        free(a);
-        return NULL;
+        return mfree(a);
 }
 
 void link_address_add_rrs(LinkAddress *a, bool force_remove) {
@@ -488,7 +708,7 @@ void link_address_add_rrs(LinkAddress *a, bool force_remove) {
         if (a->family == AF_INET) {
 
                 if (!force_remove &&
-                    link_address_relevant(a) &&
+                    link_address_relevant(a, true) &&
                     a->link->llmnr_ipv4_scope &&
                     a->link->llmnr_support == RESOLVE_SUPPORT_YES &&
                     a->link->manager->llmnr_support == RESOLVE_SUPPORT_YES) {
@@ -545,7 +765,7 @@ void link_address_add_rrs(LinkAddress *a, bool force_remove) {
         if (a->family == AF_INET6) {
 
                 if (!force_remove &&
-                    link_address_relevant(a) &&
+                    link_address_relevant(a, true) &&
                     a->link->llmnr_ipv6_scope &&
                     a->link->llmnr_support == RESOLVE_SUPPORT_YES &&
                     a->link->manager->llmnr_support == RESOLVE_SUPPORT_YES) {
@@ -622,14 +842,272 @@ int link_address_update_rtnl(LinkAddress *a, sd_netlink_message *m) {
         return 0;
 }
 
-bool link_address_relevant(LinkAddress *a) {
+bool link_address_relevant(LinkAddress *a, bool local_multicast) {
         assert(a);
 
         if (a->flags & (IFA_F_DEPRECATED|IFA_F_TENTATIVE))
                 return false;
 
-        if (IN_SET(a->scope, RT_SCOPE_HOST, RT_SCOPE_NOWHERE))
+        if (a->scope >= (local_multicast ? RT_SCOPE_HOST : RT_SCOPE_LINK))
                 return false;
 
         return true;
 }
+
+static bool link_needs_save(Link *l) {
+        assert(l);
+
+        /* Returns true if any of the settings where set different from the default */
+
+        if (l->is_managed)
+                return false;
+
+        if (l->llmnr_support != RESOLVE_SUPPORT_YES ||
+            l->mdns_support != RESOLVE_SUPPORT_NO ||
+            l->dnssec_mode != _DNSSEC_MODE_INVALID)
+                return true;
+
+        if (l->dns_servers ||
+            l->search_domains)
+                return true;
+
+        if (!set_isempty(l->dnssec_negative_trust_anchors))
+                return true;
+
+        return false;
+}
+
+int link_save_user(Link *l) {
+        _cleanup_free_ char *temp_path = NULL;
+        _cleanup_fclose_ FILE *f = NULL;
+        const char *v;
+        int r;
+
+        assert(l);
+        assert(l->state_file);
+
+        if (!link_needs_save(l)) {
+                (void) unlink(l->state_file);
+                return 0;
+        }
+
+        r = mkdir_parents(l->state_file, 0700);
+        if (r < 0)
+                goto fail;
+
+        r = fopen_temporary(l->state_file, &f, &temp_path);
+        if (r < 0)
+                goto fail;
+
+        fputs("# This is private data. Do not parse.\n", f);
+
+        v = resolve_support_to_string(l->llmnr_support);
+        if (v)
+                fprintf(f, "LLMNR=%s\n", v);
+
+        v = resolve_support_to_string(l->mdns_support);
+        if (v)
+                fprintf(f, "MDNS=%s\n", v);
+
+        v = dnssec_mode_to_string(l->dnssec_mode);
+        if (v)
+                fprintf(f, "DNSSEC=%s\n", v);
+
+        if (l->dns_servers) {
+                DnsServer *server;
+
+                fputs("SERVERS=", f);
+                LIST_FOREACH(servers, server, l->dns_servers) {
+
+                        if (server != l->dns_servers)
+                                fputc(' ', f);
+
+                        v = dns_server_string(server);
+                        if (!v) {
+                                r = -ENOMEM;
+                                goto fail;
+                        }
+
+                        fputs(v, f);
+                }
+                fputc('\n', f);
+        }
+
+        if (l->search_domains) {
+                DnsSearchDomain *domain;
+
+                fputs("DOMAINS=", f);
+                LIST_FOREACH(domains, domain, l->search_domains) {
+
+                        if (domain != l->search_domains)
+                                fputc(' ', f);
+
+                        if (domain->route_only)
+                                fputc('~', f);
+
+                        fputs(DNS_SEARCH_DOMAIN_NAME(domain), f);
+                }
+                fputc('\n', f);
+        }
+
+        if (!set_isempty(l->dnssec_negative_trust_anchors)) {
+                bool space = false;
+                Iterator i;
+                char *nta;
+
+                fputs("NTAS=", f);
+                SET_FOREACH(nta, l->dnssec_negative_trust_anchors, i) {
+
+                        if (space)
+                                fputc(' ', f);
+
+                        fputs(nta, f);
+                        space = true;
+                }
+                fputc('\n', f);
+        }
+
+        r = fflush_and_check(f);
+        if (r < 0)
+                goto fail;
+
+        if (rename(temp_path, l->state_file) < 0) {
+                r = -errno;
+                goto fail;
+        }
+
+        return 0;
+
+fail:
+        (void) unlink(l->state_file);
+
+        if (temp_path)
+                (void) unlink(temp_path);
+
+        return log_error_errno(r, "Failed to save link data %s: %m", l->state_file);
+}
+
+int link_load_user(Link *l) {
+        _cleanup_free_ char
+                *llmnr = NULL,
+                *mdns = NULL,
+                *dnssec = NULL,
+                *servers = NULL,
+                *domains = NULL,
+                *ntas = NULL;
+
+        ResolveSupport s;
+        int r;
+
+        assert(l);
+        assert(l->state_file);
+
+        /* Try to load only a single time */
+        if (l->loaded)
+                return 0;
+        l->loaded = true;
+
+        if (l->is_managed)
+                return 0; /* if the device is managed, then networkd is our configuration source, not the bus API */
+
+        r = parse_env_file(l->state_file, NEWLINE,
+                           "LLMNR", &llmnr,
+                           "MDNS", &mdns,
+                           "DNSSEC", &dnssec,
+                           "SERVERS", &servers,
+                           "DOMAINS", &domains,
+                           "NTAS", &ntas,
+                           NULL);
+        if (r == -ENOENT)
+                return 0;
+        if (r < 0)
+                goto fail;
+
+        link_flush_settings(l);
+
+        /* If we can't recognize the LLMNR or MDNS setting we don't override the default */
+        s = resolve_support_from_string(llmnr);
+        if (s >= 0)
+                l->llmnr_support = s;
+
+        s = resolve_support_from_string(mdns);
+        if (s >= 0)
+                l->mdns_support = s;
+
+        /* If we can't recognize the DNSSEC setting, then set it to invalid, so that the daemon default is used. */
+        l->dnssec_mode = dnssec_mode_from_string(dnssec);
+
+        if (servers) {
+                const char *p = servers;
+
+                for (;;) {
+                        _cleanup_free_ char *word = NULL;
+
+                        r = extract_first_word(&p, &word, NULL, 0);
+                        if (r < 0)
+                                goto fail;
+                        if (r == 0)
+                                break;
+
+                        r = link_update_dns_server_one(l, word);
+                        if (r < 0) {
+                                log_debug_errno(r, "Failed to load DNS server '%s', ignoring: %m", word);
+                                continue;
+                        }
+                }
+        }
+
+        if (domains) {
+                const char *p = domains;
+
+                for (;;) {
+                        _cleanup_free_ char *word = NULL;
+                        const char *n;
+                        bool is_route;
+
+                        r = extract_first_word(&p, &word, NULL, 0);
+                        if (r < 0)
+                                goto fail;
+                        if (r == 0)
+                                break;
+
+                        is_route = word[0] == '~';
+                        n = is_route ? word + 1 : word;
+
+                        r = link_update_search_domain_one(l, n, is_route);
+                        if (r < 0) {
+                                log_debug_errno(r, "Failed to load search domain '%s', ignoring: %m", word);
+                                continue;
+                        }
+                }
+        }
+
+        if (ntas) {
+                _cleanup_set_free_free_ Set *ns = NULL;
+
+                ns = set_new(&dns_name_hash_ops);
+                if (!ns) {
+                        r = -ENOMEM;
+                        goto fail;
+                }
+
+                r = set_put_strsplit(ns, ntas, NULL, 0);
+                if (r < 0)
+                        goto fail;
+
+                l->dnssec_negative_trust_anchors = ns;
+                ns = NULL;
+        }
+
+        return 0;
+
+fail:
+        return log_error_errno(r, "Failed to load link data %s: %m", l->state_file);
+}
+
+void link_remove_user(Link *l) {
+        assert(l);
+        assert(l->state_file);
+
+        (void) unlink(l->state_file);
+}