b652d4a209
This adds a mode that makes resolved automatically downgrade from DNSSEC support to classic non-DNSSEC resolving if the configured DNS server is not capable of DNSSEC. Enabling this mode increases compatibility with crappy network equipment, but of course opens up the system to downgrading attacks. The new mode can be enabled by setting DNSSEC=downgrade-ok in resolved.conf. DNSSEC=yes otoh remains a "strict" mode, where DNS resolving rather fails then allow downgrading. Downgrading is done: - when the server does not support EDNS0+DO - or when the server supports it but does not augment returned RRs with RRSIGs. The latter is detected when requesting DS or SOA RRs for the root domain (which is necessary to do proofs for unsigned data)
124 lines
3.9 KiB
C
124 lines
3.9 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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#pragma once
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/***
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This file is part of systemd.
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Copyright 2014 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include "in-addr-util.h"
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typedef struct DnsServer DnsServer;
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typedef enum DnsServerType {
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DNS_SERVER_SYSTEM,
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DNS_SERVER_FALLBACK,
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DNS_SERVER_LINK,
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} DnsServerType;
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typedef enum DnsServerFeatureLevel {
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DNS_SERVER_FEATURE_LEVEL_TCP,
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DNS_SERVER_FEATURE_LEVEL_UDP,
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DNS_SERVER_FEATURE_LEVEL_EDNS0,
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DNS_SERVER_FEATURE_LEVEL_DO,
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DNS_SERVER_FEATURE_LEVEL_LARGE,
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_DNS_SERVER_FEATURE_LEVEL_MAX,
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_DNS_SERVER_FEATURE_LEVEL_INVALID = -1
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} DnsServerFeatureLevel;
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#define DNS_SERVER_FEATURE_LEVEL_WORST 0
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#define DNS_SERVER_FEATURE_LEVEL_BEST (_DNS_SERVER_FEATURE_LEVEL_MAX - 1)
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const char* dns_server_feature_level_to_string(int i) _const_;
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int dns_server_feature_level_from_string(const char *s) _pure_;
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#include "resolved-link.h"
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#include "resolved-manager.h"
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struct DnsServer {
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Manager *manager;
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unsigned n_ref;
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DnsServerType type;
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Link *link;
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int family;
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union in_addr_union address;
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usec_t resend_timeout;
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usec_t max_rtt;
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DnsServerFeatureLevel verified_features;
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DnsServerFeatureLevel possible_features;
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size_t received_udp_packet_max;
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unsigned n_failed_attempts;
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usec_t verified_usec;
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usec_t features_grace_period_usec;
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/* Indicates whether responses are augmented with RRSIG by
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* server or not. Note that this is orthogonal to the feature
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* level stuff, as it's only information describing responses,
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* and has no effect on how the questions are asked. */
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bool rrsig_missing:1;
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/* Used when GC'ing old DNS servers when configuration changes. */
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bool marked:1;
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/* If linked is set, then this server appears in the servers linked list */
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bool linked:1;
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LIST_FIELDS(DnsServer, servers);
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};
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int dns_server_new(
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Manager *m,
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DnsServer **ret,
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DnsServerType type,
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Link *link,
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int family,
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const union in_addr_union *address);
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DnsServer* dns_server_ref(DnsServer *s);
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DnsServer* dns_server_unref(DnsServer *s);
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void dns_server_unlink(DnsServer *s);
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void dns_server_move_back_and_unmark(DnsServer *s);
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void dns_server_packet_received(DnsServer *s, DnsServerFeatureLevel features, usec_t rtt, size_t size);
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void dns_server_packet_lost(DnsServer *s, DnsServerFeatureLevel features, usec_t usec);
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void dns_server_packet_failed(DnsServer *s, DnsServerFeatureLevel features);
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void dns_server_packet_rrsig_missing(DnsServer *s);
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DnsServer *dns_server_find(DnsServer *first, int family, const union in_addr_union *in_addr);
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void dns_server_unlink_all(DnsServer *first);
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void dns_server_unlink_marked(DnsServer *first);
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void dns_server_mark_all(DnsServer *first);
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DnsServer *manager_get_first_dns_server(Manager *m, DnsServerType t);
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DnsServer *manager_set_dns_server(Manager *m, DnsServer *s);
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DnsServer *manager_get_dns_server(Manager *m);
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void manager_next_dns_server(Manager *m);
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DEFINE_TRIVIAL_CLEANUP_FUNC(DnsServer*, dns_server_unref);
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DnsServerFeatureLevel dns_server_possible_features(DnsServer *s);
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extern const struct hash_ops dns_server_hash_ops;
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