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/* * Copyright (C) Internet Systems Consortium, Inc. ("ISC") * * This Source Code Form is subject to the terms of the Mozilla Public * License, v. 2.0. If a copy of the MPL was not distributed with this * file, you can obtain one at https://mozilla.org/MPL/2.0/. * * See the COPYRIGHT file distributed with this work for additional * information regarding copyright ownership. */ #ifndef DNS_RRL_H #define DNS_RRL_H 1 /* * Rate limit DNS responses. */ #include <inttypes.h> #include <stdbool.h> #include <isc/lang.h> #include <dns/fixedname.h> #include <dns/rdata.h> #include <dns/types.h> ISC_LANG_BEGINDECLS /* * Memory allocation or other failures. */ #define DNS_RRL_LOG_FAIL ISC_LOG_WARNING /* * dropped or slipped responses. */ #define DNS_RRL_LOG_DROP ISC_LOG_INFO /* * Major events in dropping or slipping. */ #define DNS_RRL_LOG_DEBUG1 ISC_LOG_DEBUG(3) /* * Limit computations. */ #define DNS_RRL_LOG_DEBUG2 ISC_LOG_DEBUG(4) /* * Even less interesting. */ #define DNS_RRL_LOG_DEBUG3 ISC_LOG_DEBUG(9) #define DNS_RRL_LOG_ERR_LEN 64 #define DNS_RRL_LOG_BUF_LEN \ (sizeof("would continue limiting") + DNS_RRL_LOG_ERR_LEN + \ sizeof(" responses to ") + ISC_NETADDR_FORMATSIZE + \ sizeof("/128 for IN ") + DNS_RDATATYPE_FORMATSIZE + \ DNS_NAME_FORMATSIZE) typedef struct dns_rrl_hash dns_rrl_hash_t; /* * Response types. */ typedef enum { DNS_RRL_RTYPE_FREE = 0, DNS_RRL_RTYPE_QUERY, DNS_RRL_RTYPE_REFERRAL, DNS_RRL_RTYPE_NODATA, DNS_RRL_RTYPE_NXDOMAIN, DNS_RRL_RTYPE_ERROR, DNS_RRL_RTYPE_ALL, DNS_RRL_RTYPE_TCP, } dns_rrl_rtype_t; /* * A rate limit bucket key. * This should be small to limit the total size of the database. * The hash of the qname should be wide enough to make the probability * of collisions among requests from a single IP address block less than 50%. * We need a 32-bit hash value for 10000 qps (e.g. random qnames forged * by attacker) to collide with legitimate qnames from the target with * probability at most 1%. */ #define DNS_RRL_MAX_PREFIX 64 typedef union dns_rrl_key dns_rrl_key_t; struct dns__rrl_key { uint32_t ip[DNS_RRL_MAX_PREFIX / 32]; uint32_t qname_hash; dns_rdatatype_t qtype; uint8_t qclass; unsigned int rtype : 4; /* dns_rrl_rtype_t */ unsigned int ipv6 : 1; }; union dns_rrl_key { struct dns__rrl_key s; uint16_t w[sizeof(struct dns__rrl_key) / sizeof(uint16_t)]; }; /* * A rate-limit entry. * This should be small to limit the total size of the table of entries. */ typedef struct dns_rrl_entry dns_rrl_entry_t; typedef ISC_LIST(dns_rrl_entry_t) dns_rrl_bin_t; struct dns_rrl_entry { ISC_LINK(dns_rrl_entry_t) lru; ISC_LINK(dns_rrl_entry_t) hlink; dns_rrl_key_t key; #define DNS_RRL_RESPONSE_BITS 24 signed int responses : DNS_RRL_RESPONSE_BITS; #define DNS_RRL_QNAMES_BITS 8 unsigned int log_qname : DNS_RRL_QNAMES_BITS; #define DNS_RRL_TS_GEN_BITS 2 unsigned int ts_gen : DNS_RRL_TS_GEN_BITS; unsigned int ts_valid : 1; #define DNS_RRL_HASH_GEN_BITS 1 unsigned int hash_gen : DNS_RRL_HASH_GEN_BITS; unsigned int logged : 1; #define DNS_RRL_LOG_BITS 11 unsigned int log_secs : DNS_RRL_LOG_BITS; #define DNS_RRL_TS_BITS 12 unsigned int ts : DNS_RRL_TS_BITS; #define DNS_RRL_MAX_SLIP 10 unsigned int slip_cnt : 4; }; #define DNS_RRL_MAX_TIME_TRAVEL 5 #define DNS_RRL_FOREVER (1 << DNS_RRL_TS_BITS) #define DNS_RRL_MAX_TS (DNS_RRL_FOREVER - 1) #define DNS_RRL_MAX_RESPONSES ((1 << (DNS_RRL_RESPONSE_BITS - 1)) - 1) #define DNS_RRL_MAX_WINDOW 3600 #if DNS_RRL_MAX_WINDOW >= DNS_RRL_MAX_TS #error "DNS_RRL_MAX_WINDOW is too large" #endif /* if DNS_RRL_MAX_WINDOW >= DNS_RRL_MAX_TS */ #define DNS_RRL_MAX_RATE 1000 #if DNS_RRL_MAX_RATE >= (DNS_RRL_MAX_RESPONSES / DNS_RRL_MAX_WINDOW) #error "DNS_RRL_MAX_rate is too large" #endif /* if DNS_RRL_MAX_RATE >= (DNS_RRL_MAX_RESPONSES / DNS_RRL_MAX_WINDOW) \ */ #if (1 << DNS_RRL_LOG_BITS) >= DNS_RRL_FOREVER #error DNS_RRL_LOG_BITS is too big #endif /* if (1 << DNS_RRL_LOG_BITS) >= DNS_RRL_FOREVER */ #define DNS_RRL_MAX_LOG_SECS 1800 #if DNS_RRL_MAX_LOG_SECS >= (1 << DNS_RRL_LOG_BITS) #error "DNS_RRL_MAX_LOG_SECS is too large" #endif /* if DNS_RRL_MAX_LOG_SECS >= (1 << DNS_RRL_LOG_BITS) */ #define DNS_RRL_STOP_LOG_SECS 60 #if DNS_RRL_STOP_LOG_SECS >= (1 << DNS_RRL_LOG_BITS) #error "DNS_RRL_STOP_LOG_SECS is too large" #endif /* if DNS_RRL_STOP_LOG_SECS >= (1 << DNS_RRL_LOG_BITS) */ /* * A hash table of rate-limit entries. */ struct dns_rrl_hash { isc_stdtime_t check_time; unsigned int gen : DNS_RRL_HASH_GEN_BITS; int length; dns_rrl_bin_t bins[1]; }; /* * A block of rate-limit entries. */ typedef struct dns_rrl_block dns_rrl_block_t; struct dns_rrl_block { ISC_LINK(dns_rrl_block_t) link; int size; dns_rrl_entry_t entries[1]; }; /* * A rate limited qname buffer. */ typedef struct dns_rrl_qname_buf dns_rrl_qname_buf_t; struct dns_rrl_qname_buf { ISC_LINK(dns_rrl_qname_buf_t) link; const dns_rrl_entry_t *e; unsigned int index; dns_fixedname_t qname; }; typedef struct dns_rrl_rate dns_rrl_rate_t; struct dns_rrl_rate { int r; int scaled; const char *str; }; /* * Per-view query rate limit parameters and a pointer to database. */ typedef struct dns_rrl dns_rrl_t; struct dns_rrl { isc_mutex_t lock; isc_mem_t *mctx; bool log_only; dns_rrl_rate_t responses_per_second; dns_rrl_rate_t referrals_per_second; dns_rrl_rate_t nodata_per_second; dns_rrl_rate_t nxdomains_per_second; dns_rrl_rate_t errors_per_second; dns_rrl_rate_t all_per_second; dns_rrl_rate_t slip; int window; double qps_scale; int max_entries; dns_acl_t *exempt; int num_entries; int qps_responses; isc_stdtime_t qps_time; double qps; unsigned int probes; unsigned int searches; ISC_LIST(dns_rrl_block_t) blocks; ISC_LIST(dns_rrl_entry_t) lru; dns_rrl_hash_t *hash; dns_rrl_hash_t *old_hash; unsigned int hash_gen; unsigned int ts_gen; #define DNS_RRL_TS_BASES (1 << DNS_RRL_TS_GEN_BITS) isc_stdtime_t ts_bases[DNS_RRL_TS_BASES]; int ipv4_prefixlen; uint32_t ipv4_mask; int ipv6_prefixlen; uint32_t ipv6_mask[4]; isc_stdtime_t log_stops_time; dns_rrl_entry_t *last_logged; int num_logged; int num_qnames; ISC_LIST(dns_rrl_qname_buf_t) qname_free; #define DNS_RRL_QNAMES (1 << DNS_RRL_QNAMES_BITS) dns_rrl_qname_buf_t *qnames[DNS_RRL_QNAMES]; }; typedef enum { DNS_RRL_RESULT_OK, DNS_RRL_RESULT_DROP, DNS_RRL_RESULT_SLIP, } dns_rrl_result_t; dns_rrl_result_t dns_rrl(dns_view_t *view, const isc_sockaddr_t *client_addr, bool is_tcp, dns_rdataclass_t rdclass, dns_rdatatype_t qtype, const dns_name_t *qname, isc_result_t resp_result, isc_stdtime_t now, bool wouldlog, char *log_buf, unsigned int log_buf_len); void dns_rrl_view_destroy(dns_view_t *view); isc_result_t dns_rrl_init(dns_rrl_t **rrlp, dns_view_t *view, int min_entries); ISC_LANG_ENDDECLS #endif /* DNS_RRL_H */