547973dea7
This adds initial support for validating RRSIG/DNSKEY/DS chains when doing lookups. Proof-of-non-existance, or proof-of-unsigned-zones is not implemented yet. With this change DnsTransaction objects will generate additional DnsTransaction objects when looking for DNSKEY or DS RRs to validate an RRSIG on a response. DnsTransaction objects are thus created for three reasons now: 1) Because a user asked for something to be resolved, i.e. requested by a DnsQuery/DnsQueryCandidate object. 2) As result of LLMNR RR probing, requested by a DnsZoneItem. 3) Because another DnsTransaction requires the requested RRs for validation of its own response. DnsTransactions are shared between all these users, and are GC automatically as soon as all of these users don't need a specific transaction anymore. To unify the handling of these three reasons for existance for a DnsTransaction, a new common naming is introduced: each DnsTransaction now tracks its "owners" via a Set* object named "notify_xyz", containing all owners to notify on completion. A new DnsTransaction state is introduced called "VALIDATING" that is entered after a response has been receieved which needs to be validated, as long as we are still waiting for the DNSKEY/DS RRs from other DnsTransactions. This patch will request the DNSKEY/DS RRs bottom-up, and then validate them top-down. Caching of RRs is now only done after verification, so that the cache is not poisoned with known invalid data. The "DnsAnswer" object gained a substantial number of new calls, since we need to add/remove RRs to it dynamically now.
158 lines
5.3 KiB
C
158 lines
5.3 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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typedef struct DnsTransaction DnsTransaction;
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typedef enum DnsTransactionState DnsTransactionState;
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typedef enum DnsTransactionSource DnsTransactionSource;
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enum DnsTransactionState {
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DNS_TRANSACTION_NULL,
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DNS_TRANSACTION_PENDING,
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DNS_TRANSACTION_VALIDATING,
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DNS_TRANSACTION_FAILURE,
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DNS_TRANSACTION_SUCCESS,
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DNS_TRANSACTION_NO_SERVERS,
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DNS_TRANSACTION_TIMEOUT,
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DNS_TRANSACTION_ATTEMPTS_MAX_REACHED,
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DNS_TRANSACTION_INVALID_REPLY,
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DNS_TRANSACTION_RESOURCES,
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DNS_TRANSACTION_ABORTED,
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DNS_TRANSACTION_DNSSEC_FAILED,
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_DNS_TRANSACTION_STATE_MAX,
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_DNS_TRANSACTION_STATE_INVALID = -1
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};
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#define DNS_TRANSACTION_IS_LIVE(state) IN_SET((state), DNS_TRANSACTION_NULL, DNS_TRANSACTION_PENDING, DNS_TRANSACTION_VALIDATING)
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enum DnsTransactionSource {
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DNS_TRANSACTION_NETWORK,
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DNS_TRANSACTION_CACHE,
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DNS_TRANSACTION_ZONE,
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DNS_TRANSACTION_TRUST_ANCHOR,
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_DNS_TRANSACTION_SOURCE_MAX,
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_DNS_TRANSACTION_SOURCE_INVALID = -1
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};
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#include "resolved-dns-answer.h"
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#include "resolved-dns-packet.h"
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#include "resolved-dns-question.h"
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#include "resolved-dns-scope.h"
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struct DnsTransaction {
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DnsScope *scope;
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DnsResourceKey *key;
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DnsTransactionState state;
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DnssecResult dnssec_result;
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uint16_t id;
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bool initial_jitter_scheduled;
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bool initial_jitter_elapsed;
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DnsPacket *sent, *received;
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DnsAnswer *answer;
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int answer_rcode;
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DnsTransactionSource answer_source;
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bool answer_authenticated;
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/* Contains DS and DNSKEY RRs we already verified and need to authenticate this reply */
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DnsAnswer *validated_keys;
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usec_t start_usec;
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usec_t next_attempt_after;
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sd_event_source *timeout_event_source;
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unsigned n_attempts;
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int dns_udp_fd;
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sd_event_source *dns_udp_event_source;
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/* The active server */
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DnsServer *server;
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/* The features of the DNS server at time of transaction start */
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DnsServerFeatureLevel current_features;
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/* TCP connection logic, if we need it */
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DnsStream *stream;
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/* Query candidates this transaction is referenced by and that
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* shall be notified about this specific transaction
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* completing. */
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Set *notify_query_candidates;
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/* Zone items this transaction is referenced by and that shall
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* be notified about completion. */
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Set *notify_zone_items;
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/* Other transactions that this transactions is referenced by
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* and that shall be notified about completion. This is used
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* when transactions want to validate their RRsets, but need
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* another DNSKEY or DS RR to do so. */
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Set *notify_transactions;
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/* The opposite direction: the transactions this transaction
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* created in order to request DNSKEY or DS RRs. */
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Set *dnssec_transactions;
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unsigned block_gc;
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LIST_FIELDS(DnsTransaction, transactions_by_scope);
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};
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int dns_transaction_new(DnsTransaction **ret, DnsScope *s, DnsResourceKey *key);
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DnsTransaction* dns_transaction_free(DnsTransaction *t);
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void dns_transaction_gc(DnsTransaction *t);
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int dns_transaction_go(DnsTransaction *t);
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void dns_transaction_process_reply(DnsTransaction *t, DnsPacket *p);
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void dns_transaction_complete(DnsTransaction *t, DnsTransactionState state);
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void dns_transaction_notify(DnsTransaction *t, DnsTransaction *source);
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int dns_transaction_validate_dnssec(DnsTransaction *t);
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int dns_transaction_request_dnssec_keys(DnsTransaction *t);
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const char* dns_transaction_state_to_string(DnsTransactionState p) _const_;
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DnsTransactionState dns_transaction_state_from_string(const char *s) _pure_;
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const char* dns_transaction_source_to_string(DnsTransactionSource p) _const_;
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DnsTransactionSource dns_transaction_source_from_string(const char *s) _pure_;
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/* LLMNR Jitter interval, see RFC 4795 Section 7 */
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#define LLMNR_JITTER_INTERVAL_USEC (100 * USEC_PER_MSEC)
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/* mDNS Jitter interval, see RFC 6762 Section 5.2 */
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#define MDNS_JITTER_MIN_USEC (20 * USEC_PER_MSEC)
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#define MDNS_JITTER_RANGE_USEC (100 * USEC_PER_MSEC)
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/* Maximum attempts to send DNS requests, across all DNS servers */
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#define DNS_TRANSACTION_ATTEMPTS_MAX 16
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/* Maximum attempts to send LLMNR requests, see RFC 4795 Section 2.7 */
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#define LLMNR_TRANSACTION_ATTEMPTS_MAX 3
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#define TRANSACTION_ATTEMPTS_MAX(p) ((p) == DNS_PROTOCOL_LLMNR ? LLMNR_TRANSACTION_ATTEMPTS_MAX : DNS_TRANSACTION_ATTEMPTS_MAX)
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