Index: contrib/bind9/CHANGES =================================================================== --- contrib/bind9/CHANGES.orig +++ contrib/bind9/CHANGES @@ -1,3 +1,14 @@ +4006. [security] A flaw in delegation handling could be exploited + to put named into an infinite loop. This has + been addressed by placing limits on the number + of levels of recursion named will allow (default 7), + and the number of iterative queries that it will + send (default 50) before terminating a recursive + query (CVE-2014-8500). + + The recursion depth limit is configured via the + "max-recursion-depth" option. [RT #35780] + --- 9.9.5 released --- --- 9.9.5rc2 released --- Index: contrib/bind9/bin/named/config.c =================================================================== --- contrib/bind9/bin/named/config.c.orig +++ contrib/bind9/bin/named/config.c @@ -15,8 +15,6 @@ * PERFORMANCE OF THIS SOFTWARE. */ -/* $Id: config.c,v 1.123 2012/01/06 23:46:41 tbox Exp $ */ - /*! \file */ #include @@ -160,6 +158,7 @@ dnssec-accept-expired no;\n\ clients-per-query 10;\n\ max-clients-per-query 100;\n\ + max-recursion-depth 7;\n\ zero-no-soa-ttl-cache no;\n\ nsec3-test-zone no;\n\ allow-new-zones no;\n\ Index: contrib/bind9/bin/named/query.c =================================================================== --- contrib/bind9/bin/named/query.c.orig +++ contrib/bind9/bin/named/query.c @@ -3872,12 +3872,11 @@ peeraddr = &client->peeraddr; else peeraddr = NULL; - result = dns_resolver_createfetch2(client->view->resolver, + result = dns_resolver_createfetch3(client->view->resolver, qname, qtype, qdomain, nameservers, NULL, peeraddr, client->message->id, - client->query.fetchoptions, - client->task, - query_resume, client, + client->query.fetchoptions, 0, + client->task, query_resume, client, rdataset, sigrdataset, &client->query.fetch); Index: contrib/bind9/bin/named/server.c =================================================================== --- contrib/bind9/bin/named/server.c.orig +++ contrib/bind9/bin/named/server.c @@ -3141,6 +3141,11 @@ cfg_obj_asuint32(obj), max_clients_per_query); + obj = NULL; + result = ns_config_get(maps, "max-recursion-depth", &obj); + INSIST(result == ISC_R_SUCCESS); + dns_resolver_setmaxdepth(view->resolver, cfg_obj_asuint32(obj)); + #ifdef ALLOW_FILTER_AAAA_ON_V4 obj = NULL; result = ns_config_get(maps, "filter-aaaa-on-v4", &obj); Index: contrib/bind9/lib/dns/adb.c =================================================================== --- contrib/bind9/lib/dns/adb.c.orig +++ contrib/bind9/lib/dns/adb.c @@ -201,6 +201,7 @@ unsigned int magic; dns_fetch_t *fetch; dns_rdataset_t rdataset; + unsigned int depth; }; /*% @@ -301,7 +302,7 @@ static isc_boolean_t clean_namehooks(dns_adb_t *, dns_adbnamehooklist_t *); static void clean_target(dns_adb_t *, dns_name_t *); static void clean_finds_at_name(dns_adbname_t *, isc_eventtype_t, - unsigned int); + isc_uint32_t, unsigned int); static isc_boolean_t check_expire_namehooks(dns_adbname_t *, isc_stdtime_t); static isc_boolean_t check_expire_entry(dns_adb_t *, dns_adbentry_t **, isc_stdtime_t); @@ -309,7 +310,7 @@ static isc_result_t dbfind_name(dns_adbname_t *, isc_stdtime_t, dns_rdatatype_t); static isc_result_t fetch_name(dns_adbname_t *, isc_boolean_t, - dns_rdatatype_t); + unsigned int, dns_rdatatype_t); static inline void check_exit(dns_adb_t *); static void destroy(dns_adb_t *); static isc_boolean_t shutdown_names(dns_adb_t *); @@ -982,7 +983,7 @@ * Clean up the name's various lists. These two are destructive * in that they will always empty the list. */ - clean_finds_at_name(name, ev, DNS_ADBFIND_ADDRESSMASK); + clean_finds_at_name(name, ev, 0, DNS_ADBFIND_ADDRESSMASK); result4 = clean_namehooks(adb, &name->v4); result6 = clean_namehooks(adb, &name->v6); clean_target(adb, &name->target); @@ -1407,7 +1408,7 @@ */ static void clean_finds_at_name(dns_adbname_t *name, isc_eventtype_t evtype, - unsigned int addrs) + isc_uint32_t qtotal, unsigned int addrs) { isc_event_t *ev; isc_task_t *task; @@ -1467,6 +1468,7 @@ ev->ev_sender = find; find->result_v4 = find_err_map[name->fetch_err]; find->result_v6 = find_err_map[name->fetch6_err]; + find->qtotal += qtotal; ev->ev_type = evtype; ev->ev_destroy = event_free; ev->ev_destroy_arg = find; @@ -1821,6 +1823,7 @@ h->flags = 0; h->result_v4 = ISC_R_UNEXPECTED; h->result_v6 = ISC_R_UNEXPECTED; + h->qtotal = 0; ISC_LINK_INIT(h, publink); ISC_LINK_INIT(h, plink); ISC_LIST_INIT(h->list); @@ -2770,6 +2773,19 @@ isc_stdtime_t now, dns_name_t *target, in_port_t port, dns_adbfind_t **findp) { + return (dns_adb_createfind2(adb, task, action, arg, name, + qname, qtype, options, now, + target, port, 0, findp)); +} + +isc_result_t +dns_adb_createfind2(dns_adb_t *adb, isc_task_t *task, isc_taskaction_t action, + void *arg, dns_name_t *name, dns_name_t *qname, + dns_rdatatype_t qtype, unsigned int options, + isc_stdtime_t now, dns_name_t *target, + in_port_t port, unsigned int depth, + dns_adbfind_t **findp) +{ dns_adbfind_t *find; dns_adbname_t *adbname; int bucket; @@ -3000,7 +3016,7 @@ * Start V4. */ if (WANT_INET(wanted_fetches) && - fetch_name(adbname, start_at_zone, + fetch_name(adbname, start_at_zone, depth, dns_rdatatype_a) == ISC_R_SUCCESS) { DP(DEF_LEVEL, "dns_adb_createfind: started A fetch for name %p", @@ -3011,7 +3027,7 @@ * Start V6. */ if (WANT_INET6(wanted_fetches) && - fetch_name(adbname, start_at_zone, + fetch_name(adbname, start_at_zone, depth, dns_rdatatype_aaaa) == ISC_R_SUCCESS) { DP(DEF_LEVEL, "dns_adb_createfind: " @@ -3627,6 +3643,7 @@ isc_result_t result; unsigned int address_type; isc_boolean_t want_check_exit = ISC_FALSE; + isc_uint32_t qtotal = 0; UNUSED(task); @@ -3637,6 +3654,8 @@ adb = name->adb; INSIST(DNS_ADB_VALID(adb)); + qtotal = dev->qtotal; + bucket = name->lock_bucket; LOCK(&adb->namelocks[bucket]); @@ -3754,6 +3773,12 @@ DP(DEF_LEVEL, "adb: fetch of '%s' %s failed: %s", buf, address_type == DNS_ADBFIND_INET ? "A" : "AAAA", dns_result_totext(dev->result)); + /* + * Don't record a failure unless this is the initial + * fetch of a chain. + */ + if (fetch->depth > 1) + goto out; /* XXXMLG Don't pound on bad servers. */ if (address_type == DNS_ADBFIND_INET) { name->expire_v4 = ISC_MIN(name->expire_v4, now + 300); @@ -3785,15 +3810,14 @@ free_adbfetch(adb, &fetch); isc_event_free(&ev); - clean_finds_at_name(name, ev_status, address_type); + clean_finds_at_name(name, ev_status, qtotal, address_type); UNLOCK(&adb->namelocks[bucket]); } static isc_result_t -fetch_name(dns_adbname_t *adbname, - isc_boolean_t start_at_zone, - dns_rdatatype_t type) +fetch_name(dns_adbname_t *adbname, isc_boolean_t start_at_zone, + unsigned int depth, dns_rdatatype_t type) { isc_result_t result; dns_adbfetch_t *fetch = NULL; @@ -3838,12 +3862,14 @@ result = ISC_R_NOMEMORY; goto cleanup; } + fetch->depth = depth; - result = dns_resolver_createfetch(adb->view->resolver, &adbname->name, - type, name, nameservers, NULL, - options, adb->task, fetch_callback, - adbname, &fetch->rdataset, NULL, - &fetch->fetch); + result = dns_resolver_createfetch3(adb->view->resolver, &adbname->name, + type, name, nameservers, NULL, + NULL, 0, options, depth, adb->task, + fetch_callback, adbname, + &fetch->rdataset, NULL, + &fetch->fetch); if (result != ISC_R_SUCCESS) goto cleanup; Index: contrib/bind9/lib/dns/include/dns/adb.h =================================================================== --- contrib/bind9/lib/dns/include/dns/adb.h.orig +++ contrib/bind9/lib/dns/include/dns/adb.h @@ -118,6 +118,8 @@ isc_result_t result_v6; /*%< RO: v6 result */ ISC_LINK(dns_adbfind_t) publink; /*%< RW: client use */ + isc_uint32_t qtotal; + /* Private */ isc_mutex_t lock; /* locks all below */ in_port_t port; @@ -334,6 +336,12 @@ dns_rdatatype_t qtype, unsigned int options, isc_stdtime_t now, dns_name_t *target, in_port_t port, dns_adbfind_t **find); +isc_result_t +dns_adb_createfind2(dns_adb_t *adb, isc_task_t *task, isc_taskaction_t action, + void *arg, dns_name_t *name, dns_name_t *qname, + dns_rdatatype_t qtype, unsigned int options, + isc_stdtime_t now, dns_name_t *target, in_port_t port, + unsigned int depth, dns_adbfind_t **find); /*%< * Main interface for clients. The adb will look up the name given in * "name" and will build up a list of found addresses, and perhaps start Index: contrib/bind9/lib/dns/include/dns/resolver.h =================================================================== --- contrib/bind9/lib/dns/include/dns/resolver.h.orig +++ contrib/bind9/lib/dns/include/dns/resolver.h @@ -82,6 +82,7 @@ isc_sockaddr_t * client; dns_messageid_t id; isc_result_t vresult; + isc_uint32_t qtotal; } dns_fetchevent_t; /* @@ -274,6 +275,18 @@ dns_rdataset_t *rdataset, dns_rdataset_t *sigrdataset, dns_fetch_t **fetchp); +isc_result_t +dns_resolver_createfetch3(dns_resolver_t *res, dns_name_t *name, + dns_rdatatype_t type, + dns_name_t *domain, dns_rdataset_t *nameservers, + dns_forwarders_t *forwarders, + isc_sockaddr_t *client, isc_uint16_t id, + unsigned int options, unsigned int depth, + isc_task_t *task, + isc_taskaction_t action, void *arg, + dns_rdataset_t *rdataset, + dns_rdataset_t *sigrdataset, + dns_fetch_t **fetchp); /*%< * Recurse to answer a question. * @@ -575,6 +588,18 @@ * \li resolver to be valid. */ +void +dns_resolver_setmaxdepth(dns_resolver_t *resolver, unsigned int maxdepth); +unsigned int +dns_resolver_getmaxdepth(dns_resolver_t *resolver); +/*% + * Get and set how many NS indirections will be followed when looking for + * nameserver addresses. + * + * Requires: + * \li resolver to be valid. + */ + ISC_LANG_ENDDECLS #endif /* DNS_RESOLVER_H */ Index: contrib/bind9/lib/dns/resolver.c =================================================================== --- contrib/bind9/lib/dns/resolver.c.orig +++ contrib/bind9/lib/dns/resolver.c @@ -131,6 +131,16 @@ #define MAXIMUM_QUERY_TIMEOUT 30 /* The maximum time in seconds for the whole query to live. */ #endif +/* The default maximum number of recursions to follow before giving up. */ +#ifndef DEFAULT_RECURSION_DEPTH +#define DEFAULT_RECURSION_DEPTH 7 +#endif + +/* The default maximum number of iterative queries to allow before giving up. */ +#ifndef DEFAULT_MAX_QUERIES +#define DEFAULT_MAX_QUERIES 50 +#endif + /*% * Maximum EDNS0 input packet size. */ @@ -297,6 +307,7 @@ isc_uint64_t duration; isc_boolean_t logged; unsigned int querysent; + unsigned int totalqueries; unsigned int referrals; unsigned int lamecount; unsigned int neterr; @@ -307,6 +318,7 @@ isc_boolean_t timeout; dns_adbaddrinfo_t *addrinfo; isc_sockaddr_t *client; + unsigned int depth; }; #define FCTX_MAGIC ISC_MAGIC('F', '!', '!', '!') @@ -418,6 +430,7 @@ isc_timer_t * spillattimer; isc_boolean_t zero_no_soa_ttl; unsigned int query_timeout; + unsigned int maxdepth; /* Locked by lock. */ unsigned int references; @@ -1093,6 +1106,7 @@ event->result == DNS_R_NCACHENXRRSET); } + event->qtotal = fctx->totalqueries; isc_task_sendanddetach(&task, ISC_EVENT_PTR(&event)); count++; } @@ -1533,7 +1547,9 @@ if (result != ISC_R_SUCCESS) goto cleanup_dispatch; } + fctx->querysent++; + fctx->totalqueries++; ISC_LIST_APPEND(fctx->queries, query, link); query->fctx->nqueries++; @@ -2186,9 +2202,10 @@ */ INSIST(!SHUTTINGDOWN(fctx)); fctx->attributes &= ~FCTX_ATTR_ADDRWAIT; - if (event->ev_type == DNS_EVENT_ADBMOREADDRESSES) + if (event->ev_type == DNS_EVENT_ADBMOREADDRESSES) { want_try = ISC_TRUE; - else { + fctx->totalqueries += find->qtotal; + } else { fctx->findfail++; if (fctx->pending == 0) { /* @@ -2471,12 +2488,13 @@ * See what we know about this address. */ find = NULL; - result = dns_adb_createfind(fctx->adb, - res->buckets[fctx->bucketnum].task, - fctx_finddone, fctx, name, - &fctx->name, fctx->type, - options, now, NULL, - res->view->dstport, &find); + result = dns_adb_createfind2(fctx->adb, + res->buckets[fctx->bucketnum].task, + fctx_finddone, fctx, name, + &fctx->name, fctx->type, + options, now, NULL, + res->view->dstport, + fctx->depth + 1, &find); if (result != ISC_R_SUCCESS) { if (result == DNS_R_ALIAS) { /* @@ -2584,6 +2602,11 @@ res = fctx->res; + if (fctx->depth > res->maxdepth) { + FCTXTRACE("too much NS indirection"); + return (DNS_R_SERVFAIL); + } + /* * Forwarders. */ @@ -3022,6 +3045,9 @@ REQUIRE(!ADDRWAIT(fctx)); + if (fctx->totalqueries > DEFAULT_MAX_QUERIES) + fctx_done(fctx, DNS_R_SERVFAIL, __LINE__); + addrinfo = fctx_nextaddress(fctx); if (addrinfo == NULL) { /* @@ -3380,6 +3406,7 @@ * Normal fctx startup. */ fctx->state = fetchstate_active; + fctx->totalqueries = 0; /* * Reset the control event for later use in shutting down * the fctx. @@ -3449,6 +3476,7 @@ event->fetch = fetch; event->client = client; event->id = id; + event->qtotal = 0; dns_fixedname_init(&event->foundname); /* @@ -3485,7 +3513,8 @@ static isc_result_t fctx_create(dns_resolver_t *res, dns_name_t *name, dns_rdatatype_t type, dns_name_t *domain, dns_rdataset_t *nameservers, - unsigned int options, unsigned int bucketnum, fetchctx_t **fctxp) + unsigned int options, unsigned int bucketnum, unsigned int depth, + fetchctx_t **fctxp) { fetchctx_t *fctx; isc_result_t result; @@ -3537,6 +3566,7 @@ fctx->state = fetchstate_init; fctx->want_shutdown = ISC_FALSE; fctx->cloned = ISC_FALSE; + fctx->depth = depth; ISC_LIST_INIT(fctx->queries); ISC_LIST_INIT(fctx->finds); ISC_LIST_INIT(fctx->altfinds); @@ -3555,6 +3585,7 @@ fctx->pending = 0; fctx->restarts = 0; fctx->querysent = 0; + fctx->totalqueries = 0; fctx->referrals = 0; TIME_NOW(&fctx->start); fctx->timeouts = 0; @@ -7731,6 +7762,7 @@ res->spillattimer = NULL; res->zero_no_soa_ttl = ISC_FALSE; res->query_timeout = DEFAULT_QUERY_TIMEOUT; + res->maxdepth = DEFAULT_RECURSION_DEPTH; res->nbuckets = ntasks; res->activebuckets = ntasks; res->buckets = isc_mem_get(view->mctx, @@ -8169,9 +8201,9 @@ dns_rdataset_t *sigrdataset, dns_fetch_t **fetchp) { - return (dns_resolver_createfetch2(res, name, type, domain, + return (dns_resolver_createfetch3(res, name, type, domain, nameservers, forwarders, NULL, 0, - options, task, action, arg, + options, 0, task, action, arg, rdataset, sigrdataset, fetchp)); } @@ -8187,6 +8219,25 @@ dns_rdataset_t *sigrdataset, dns_fetch_t **fetchp) { + return (dns_resolver_createfetch3(res, name, type, domain, + nameservers, forwarders, client, id, + options, 0, task, action, arg, + rdataset, sigrdataset, fetchp)); +} + +isc_result_t +dns_resolver_createfetch3(dns_resolver_t *res, dns_name_t *name, + dns_rdatatype_t type, + dns_name_t *domain, dns_rdataset_t *nameservers, + dns_forwarders_t *forwarders, + isc_sockaddr_t *client, dns_messageid_t id, + unsigned int options, unsigned int depth, + isc_task_t *task, + isc_taskaction_t action, void *arg, + dns_rdataset_t *rdataset, + dns_rdataset_t *sigrdataset, + dns_fetch_t **fetchp) +{ dns_fetch_t *fetch; fetchctx_t *fctx = NULL; isc_result_t result = ISC_R_SUCCESS; @@ -8273,11 +8324,12 @@ if (fctx == NULL) { result = fctx_create(res, name, type, domain, nameservers, - options, bucketnum, &fctx); + options, bucketnum, depth, &fctx); if (result != ISC_R_SUCCESS) goto unlock; new_fctx = ISC_TRUE; - } + } else if (fctx->depth > depth) + fctx->depth = depth; result = fctx_join(fctx, task, client, id, action, arg, rdataset, sigrdataset, fetch); @@ -9049,3 +9101,15 @@ resolver->query_timeout = seconds; } + +void +dns_resolver_setmaxdepth(dns_resolver_t *resolver, unsigned int maxdepth) { + REQUIRE(VALID_RESOLVER(resolver)); + resolver->maxdepth = maxdepth; +} + +unsigned int +dns_resolver_getmaxdepth(dns_resolver_t *resolver) { + REQUIRE(VALID_RESOLVER(resolver)); + return (resolver->maxdepth); +} Index: contrib/bind9/lib/isccfg/namedconf.c =================================================================== --- contrib/bind9/lib/isccfg/namedconf.c.orig +++ contrib/bind9/lib/isccfg/namedconf.c @@ -1419,6 +1419,7 @@ { "max-cache-ttl", &cfg_type_uint32, 0 }, { "max-clients-per-query", &cfg_type_uint32, 0 }, { "max-ncache-ttl", &cfg_type_uint32, 0 }, + { "max-recursion-depth", &cfg_type_uint32, 0 }, { "max-udp-size", &cfg_type_uint32, 0 }, { "min-roots", &cfg_type_uint32, CFG_CLAUSEFLAG_NOTIMP }, { "minimal-responses", &cfg_type_boolean, 0 },