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)
108 lines
3.8 KiB
C
108 lines
3.8 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 2015 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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typedef enum DnssecMode DnssecMode;
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typedef enum DnssecResult DnssecResult;
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#include "dns-domain.h"
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#include "resolved-dns-answer.h"
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#include "resolved-dns-rr.h"
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enum DnssecMode {
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/* No DNSSEC validation is done */
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DNSSEC_NO,
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/* Validate locally, if the server knows DO, but if not,
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* don't. Don't trust the AD bit. If the server doesn't do
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* DNSSEC properly, downgrade to non-DNSSEC operation. Of
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* course, we then are vulnerable to a downgrade attack, but
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* that's life and what is configured. */
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DNSSEC_DOWNGRADE_OK,
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/* Insist on DNSSEC server support, and rather fail than downgrading. */
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DNSSEC_YES,
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_DNSSEC_MODE_MAX,
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_DNSSEC_MODE_INVALID = -1
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};
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enum DnssecResult {
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/* These four are returned by dnssec_verify_rrset() */
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DNSSEC_VALIDATED,
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DNSSEC_INVALID,
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DNSSEC_SIGNATURE_EXPIRED,
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DNSSEC_UNSUPPORTED_ALGORITHM,
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/* These two are added by dnssec_verify_rrset_search() */
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DNSSEC_NO_SIGNATURE,
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DNSSEC_MISSING_KEY,
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/* These two are added by the DnsTransaction logic */
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DNSSEC_UNSIGNED,
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DNSSEC_FAILED_AUXILIARY,
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DNSSEC_NSEC_MISMATCH,
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DNSSEC_INCOMPATIBLE_SERVER,
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_DNSSEC_RESULT_MAX,
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_DNSSEC_RESULT_INVALID = -1
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};
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#define DNSSEC_CANONICAL_HOSTNAME_MAX (DNS_HOSTNAME_MAX + 2)
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/* The longest digest we'll ever generate, of all digest algorithms we support */
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#define DNSSEC_HASH_SIZE_MAX (MAX(20, 32))
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int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnskey);
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int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig);
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int dnssec_verify_rrset(DnsAnswer *answer, DnsResourceKey *key, DnsResourceRecord *rrsig, DnsResourceRecord *dnskey, usec_t realtime, DnssecResult *result);
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int dnssec_verify_rrset_search(DnsAnswer *answer, DnsResourceKey *key, DnsAnswer *validated_dnskeys, usec_t realtime, DnssecResult *result);
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int dnssec_verify_dnskey(DnsResourceRecord *dnskey, DnsResourceRecord *ds);
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int dnssec_verify_dnskey_search(DnsResourceRecord *dnskey, DnsAnswer *validated_ds);
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int dnssec_has_rrsig(DnsAnswer *a, const DnsResourceKey *key);
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uint16_t dnssec_keytag(DnsResourceRecord *dnskey);
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int dnssec_canonicalize(const char *n, char *buffer, size_t buffer_max);
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int dnssec_nsec3_hash(DnsResourceRecord *nsec3, const char *name, void *ret);
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typedef enum DnssecNsecResult {
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DNSSEC_NSEC_NO_RR, /* No suitable NSEC/NSEC3 RR found */
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DNSSEC_NSEC_UNSUPPORTED_ALGORITHM,
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DNSSEC_NSEC_NXDOMAIN,
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DNSSEC_NSEC_NODATA,
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DNSSEC_NSEC_FOUND,
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DNSSEC_NSEC_OPTOUT,
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} DnssecNsecResult;
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int dnssec_test_nsec(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result, bool *authenticated);
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const char* dnssec_mode_to_string(DnssecMode m) _const_;
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DnssecMode dnssec_mode_from_string(const char *s) _pure_;
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const char* dnssec_result_to_string(DnssecResult m) _const_;
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DnssecResult dnssec_result_from_string(const char *s) _pure_;
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