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64149353dd
This commit introduces the src/or/dos.{c|h} files that contains the code for
the Denial of Service mitigation subsystem. It currently contains basic
functions to initialize and free the subsystem. They are used at this commit.
The torrc options and consensus parameters are defined at this commit and
getters are implemented.
Signed-off-by: David Goulet <dgoulet@torproject.org>
121 lines
4.3 KiB
C
121 lines
4.3 KiB
C
/* Copyright (c) 2018, The Tor Project, Inc. */
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/* See LICENSE for licensing information */
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/*
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* \file dos.h
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* \brief Header file for dos.c
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*/
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#ifndef TOR_DOS_H
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#define TOR_DOS_H
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/* Structure that keeps stats of client connection per-IP. */
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typedef struct cc_client_stats_t {
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/* Number of allocated circuits remaining for this address. It is
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* decremented every time a new circuit is seen for this client address and
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* if the count goes to 0, we have a positive detection. */
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uint32_t circuit_bucket;
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/* When was the last time we've refilled the circuit bucket? This is used to
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* know if we need to refill the bucket when a new circuit is seen. It is
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* synchronized using approx_time(). */
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time_t last_circ_bucket_refill_ts;
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/* This client address was detected to be above the circuit creation rate
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* and this timestamp indicates until when it should remain marked as
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* detected so we can apply a defense for the address. It is synchronized
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* using the approx_time(). */
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time_t marked_until_ts;
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} cc_client_stats_t;
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/* This object is a top level object that contains everything related to the
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* per-IP client DoS mitigation. Because it is per-IP, it is used in the geoip
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* clientmap_entry_t object. */
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typedef struct dos_client_stats_t {
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/* Concurrent connection count from the specific address. 2^32 is most
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* likely way too big for the amount of allowed file descriptors. */
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uint32_t concurrent_count;
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/* Circuit creation statistics. This is only used if the circuit creation
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* subsystem has been enabled (dos_cc_enabled). */
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cc_client_stats_t cc_stats;
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} dos_client_stats_t;
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/* General API. */
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void dos_init(void);
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void dos_free_all(void);
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void dos_consensus_has_changed(const networkstatus_t *ns);
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int dos_enabled(void);
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/*
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* Circuit creation DoS mitigation subsystemn interface.
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*/
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/* DoSCircuitCreationEnabled default. Disabled by default. */
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#define DOS_CC_ENABLED_DEFAULT 0
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/* DoSCircuitCreationDefenseType maps to the dos_cc_defense_type_t enum. */
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#define DOS_CC_DEFENSE_TYPE_DEFAULT DOS_CC_DEFENSE_REFUSE_CELL
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/* DoSCircuitCreationMinConnections default */
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#define DOS_CC_MIN_CONCURRENT_CONN_DEFAULT 3
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/* DoSCircuitCreationRateTenths is 3 per seconds. */
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#define DOS_CC_CIRCUIT_RATE_TENTHS_DEFAULT (3 * 10)
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/* DoSCircuitCreationBurst default. */
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#define DOS_CC_CIRCUIT_BURST_DEFAULT 90
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/* DoSCircuitCreationDefenseTimePeriod in seconds. */
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#define DOS_CC_DEFENSE_TIME_PERIOD_DEFAULT (60 * 60)
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/* Type of defense that we can use for the circuit creation DoS mitigation. */
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typedef enum dos_cc_defense_type_t {
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/* No defense used. */
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DOS_CC_DEFENSE_NONE = 1,
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/* Refuse any cells which means a DESTROY cell will be sent back. */
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DOS_CC_DEFENSE_REFUSE_CELL = 2,
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/* Maximum value that can be used. Useful for the boundaries of the
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* consensus parameter. */
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DOS_CC_DEFENSE_MAX = 2,
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} dos_cc_defense_type_t;
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/*
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* Concurrent connection DoS mitigation interface.
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*/
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/* DoSConnectionEnabled default. Disabled by default. */
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#define DOS_CONN_ENABLED_DEFAULT 0
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/* DoSConnectionMaxConcurrentCount default. */
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#define DOS_CONN_MAX_CONCURRENT_COUNT_DEFAULT 100
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/* DoSConnectionDefenseType maps to the dos_conn_defense_type_t enum. */
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#define DOS_CONN_DEFENSE_TYPE_DEFAULT DOS_CONN_DEFENSE_CLOSE
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/* Type of defense that we can use for the concurrent connection DoS
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* mitigation. */
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typedef enum dos_conn_defense_type_t {
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/* No defense used. */
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DOS_CONN_DEFENSE_NONE = 1,
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/* Close immediately the connection meaning refuse it. */
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DOS_CONN_DEFENSE_CLOSE = 2,
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/* Maximum value that can be used. Useful for the boundaries of the
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* consensus parameter. */
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DOS_CONN_DEFENSE_MAX = 2,
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} dos_conn_defense_type_t;
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#ifdef DOS_PRIVATE
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STATIC uint32_t get_param_conn_max_concurrent_count(
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const networkstatus_t *ns);
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STATIC uint32_t get_param_cc_circuit_burst(const networkstatus_t *ns);
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STATIC uint32_t get_param_cc_min_concurrent_connection(
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const networkstatus_t *ns);
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MOCK_DECL(STATIC unsigned int, get_param_cc_enabled,
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(const networkstatus_t *ns));
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MOCK_DECL(STATIC unsigned int, get_param_conn_enabled,
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(const networkstatus_t *ns));
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#endif /* TOR_DOS_PRIVATE */
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#endif /* TOR_DOS_H */
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