Zbigniew Jędrzejewski-Szmek
0ad4efb14b
We get "upstream" dns server config from ~three places: /etc/resolv.conf,
config files, and runtime config via dbus. With this commit, we'll filter out
our own stub listeners if they are configured in either of the first two
sources. For /etc/resolv.conf this is done quitely, and for our own config
files, a LOG_INFO message is emitted, since this is a small inconsistency in
the config.
Setting loops like this over dbus is still allowed. The reason is that in the
past we didn't treat this as an error, and if we were to start responding with
an error, we could break a scenario that worked previously. E.g. NM sends us a
list of servers, and one happens to be the our own. We would just not use that
stub server before, but it'd still be shown in the dbus properties and such.
We would have to return error for the whole message, also rejecting the other
valid servers. I think it's easier to just keep that part unchanged.
Test case:
$ ls -l /etc/resolv.conf
-rw-r--r-- 1 root root 57 Dec 15 10:26 /etc/resolv.conf
$ cat /etc/resolv.conf
nameserver 192.168.150.1
options edns0 trust-ad
search .
$ cat /etc/systemd/resolved.conf.d/stub.conf
[Resolve]
DNSStubListenerExtra=192.168.150.1
$ resolvectl
...
Global
resolv.conf mode: foreign
DNS Servers: 192.168.150.1
Fallback DNS Servers: ...
(with the patch):
Global
resolv.conf mode: foreign
Fallback DNS Servers: ...
214 lines
6.2 KiB
C
214 lines
6.2 KiB
C
/* SPDX-License-Identifier: LGPL-2.1-or-later */
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#pragma once
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#include <sys/stat.h>
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#include "sd-event.h"
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#include "sd-netlink.h"
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#include "sd-network.h"
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#include "hashmap.h"
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#include "list.h"
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#include "ordered-set.h"
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#include "resolve-util.h"
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#include "varlink.h"
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typedef struct Manager Manager;
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#include "resolved-dns-query.h"
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#include "resolved-dns-search-domain.h"
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#include "resolved-dns-stream.h"
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#include "resolved-dns-stub.h"
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#include "resolved-dns-trust-anchor.h"
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#include "resolved-link.h"
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#include "resolved-socket-graveyard.h"
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#define MANAGER_SEARCH_DOMAINS_MAX 256
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#define MANAGER_DNS_SERVERS_MAX 256
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typedef struct EtcHosts {
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Hashmap *by_address;
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Hashmap *by_name;
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Set *no_address;
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} EtcHosts;
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struct Manager {
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sd_event *event;
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ResolveSupport llmnr_support;
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ResolveSupport mdns_support;
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DnssecMode dnssec_mode;
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DnsOverTlsMode dns_over_tls_mode;
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DnsCacheMode enable_cache;
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bool cache_from_localhost;
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DnsStubListenerMode dns_stub_listener_mode;
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#if ENABLE_DNS_OVER_TLS
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DnsTlsManagerData dnstls_data;
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#endif
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/* Network */
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Hashmap *links;
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sd_netlink *rtnl;
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sd_event_source *rtnl_event_source;
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sd_network_monitor *network_monitor;
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sd_event_source *network_event_source;
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/* DNS query management */
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Hashmap *dns_transactions;
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LIST_HEAD(DnsQuery, dns_queries);
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unsigned n_dns_queries;
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Hashmap *stub_queries_by_packet;
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LIST_HEAD(DnsStream, dns_streams);
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unsigned n_dns_streams[_DNS_STREAM_TYPE_MAX];
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/* Unicast dns */
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LIST_HEAD(DnsServer, dns_servers);
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LIST_HEAD(DnsServer, fallback_dns_servers);
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unsigned n_dns_servers; /* counts both main and fallback */
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DnsServer *current_dns_server;
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LIST_HEAD(DnsSearchDomain, search_domains);
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unsigned n_search_domains;
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bool need_builtin_fallbacks;
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bool read_resolv_conf;
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bool resolve_unicast_single_label;
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struct stat resolv_conf_stat;
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DnsTrustAnchor trust_anchor;
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LIST_HEAD(DnsScope, dns_scopes);
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DnsScope *unicast_scope;
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/* LLMNR */
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int llmnr_ipv4_udp_fd;
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int llmnr_ipv6_udp_fd;
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int llmnr_ipv4_tcp_fd;
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int llmnr_ipv6_tcp_fd;
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sd_event_source *llmnr_ipv4_udp_event_source;
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sd_event_source *llmnr_ipv6_udp_event_source;
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sd_event_source *llmnr_ipv4_tcp_event_source;
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sd_event_source *llmnr_ipv6_tcp_event_source;
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/* mDNS */
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int mdns_ipv4_fd;
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int mdns_ipv6_fd;
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sd_event_source *mdns_ipv4_event_source;
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sd_event_source *mdns_ipv6_event_source;
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/* DNS-SD */
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Hashmap *dnssd_services;
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/* dbus */
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sd_bus *bus;
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/* The hostname we publish on LLMNR and mDNS */
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char *full_hostname;
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char *llmnr_hostname;
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char *mdns_hostname;
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DnsResourceKey *llmnr_host_ipv4_key;
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DnsResourceKey *llmnr_host_ipv6_key;
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DnsResourceKey *mdns_host_ipv4_key;
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DnsResourceKey *mdns_host_ipv6_key;
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/* Watch the system hostname */
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int hostname_fd;
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sd_event_source *hostname_event_source;
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sd_event_source *sigusr1_event_source;
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sd_event_source *sigusr2_event_source;
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sd_event_source *sigrtmin1_event_source;
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unsigned n_transactions_total;
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unsigned n_dnssec_verdict[_DNSSEC_VERDICT_MAX];
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/* Data from /etc/hosts */
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EtcHosts etc_hosts;
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usec_t etc_hosts_last;
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struct stat etc_hosts_stat;
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bool read_etc_hosts;
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OrderedSet *dns_extra_stub_listeners;
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/* Local DNS stub on 127.0.0.53:53 */
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sd_event_source *dns_stub_udp_event_source;
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sd_event_source *dns_stub_tcp_event_source;
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/* Local DNS proxy stub on 127.0.0.54:53 */
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sd_event_source *dns_proxy_stub_udp_event_source;
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sd_event_source *dns_proxy_stub_tcp_event_source;
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Hashmap *polkit_registry;
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VarlinkServer *varlink_server;
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sd_event_source *clock_change_event_source;
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LIST_HEAD(SocketGraveyard, socket_graveyard);
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SocketGraveyard *socket_graveyard_oldest;
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size_t n_socket_graveyard;
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};
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/* Manager */
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int manager_new(Manager **ret);
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Manager* manager_free(Manager *m);
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int manager_start(Manager *m);
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uint32_t manager_find_mtu(Manager *m);
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int manager_write(Manager *m, int fd, DnsPacket *p);
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int manager_send(Manager *m, int fd, int ifindex, int family, const union in_addr_union *destination, uint16_t port, const union in_addr_union *source, DnsPacket *p);
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int manager_recv(Manager *m, int fd, DnsProtocol protocol, DnsPacket **ret);
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int manager_find_ifindex(Manager *m, int family, const union in_addr_union *in_addr);
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LinkAddress* manager_find_link_address(Manager *m, int family, const union in_addr_union *in_addr);
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void manager_refresh_rrs(Manager *m);
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int manager_next_hostname(Manager *m);
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bool manager_packet_from_local_address(Manager *m, DnsPacket *p);
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bool manager_packet_from_our_transaction(Manager *m, DnsPacket *p);
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DnsScope* manager_find_scope(Manager *m, DnsPacket *p);
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void manager_verify_all(Manager *m);
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DEFINE_TRIVIAL_CLEANUP_FUNC(Manager*, manager_free);
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/* For some reason we need some extra cmsg space on some kernels/archs. One of those days we need to figure out why */
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#define EXTRA_CMSG_SPACE 1024
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int manager_is_own_hostname(Manager *m, const char *name);
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int manager_compile_dns_servers(Manager *m, OrderedSet **servers);
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int manager_compile_search_domains(Manager *m, OrderedSet **domains, int filter_route);
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DnssecMode manager_get_dnssec_mode(Manager *m);
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bool manager_dnssec_supported(Manager *m);
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DnsOverTlsMode manager_get_dns_over_tls_mode(Manager *m);
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void manager_dnssec_verdict(Manager *m, DnssecVerdict verdict, const DnsResourceKey *key);
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bool manager_routable(Manager *m);
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void manager_flush_caches(Manager *m, int log_level);
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void manager_reset_server_features(Manager *m);
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void manager_cleanup_saved_user(Manager *m);
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bool manager_next_dnssd_names(Manager *m);
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bool manager_server_address_is_stub(Manager *m, int family, const union in_addr_union *address, uint16_t port);
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bool manager_server_is_stub(Manager *m, DnsServer *s);
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int socket_disable_pmtud(int fd, int af);
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