From d7ff9a1c41bf0ba9773cb3adb08b48b9fd57c956 Mon Sep 17 00:00:00 2001 From: Mark Andrews Date: Sat, 27 Feb 2016 11:23:50 +1100 Subject: [PATCH] 4322. [security] Duplicate EDNS COOKIE options in a response could trigger an assertion failure. (CVE-2016-2088) [RT #41809] (cherry picked from commit 455c0848f80a8acda27aad1466c72987cafaa029) (cherry picked from commit 7cd300abd6ee8b8ee8730593daf742ba53f90bc3) Upstream-Status: Backport CVE: CVE-2016-2088 minor fixup to get to apply. Signed-off-by: Armin Kuster --- CHANGES | 5 +++++ bin/dig/dighost.c | 9 +++++++++ bin/named/client.c | 33 +++++++++++++++++++++++---------- doc/arm/notes.xml | 7 +++++++ lib/dns/resolver.c | 14 +++++++++++++- 5 files changed, 57 insertions(+), 11 deletions(-) Index: bind-9.10.2-P4/CHANGES =================================================================== --- bind-9.10.2-P4.orig/CHANGES +++ bind-9.10.2-P4/CHANGES @@ -1,3 +1,7 @@ +4322. [security] Duplicate EDNS COOKIE options in a response could + trigger an assertion failure. (CVE-2016-2088) + [RT #41809] + 4319. [security] Fix resolver assertion failure due to improper DNAME handling when parsing fetch reply messages. (CVE-2016-1286) [RT #41753] Index: bind-9.10.2-P4/bin/dig/dighost.c =================================================================== --- bind-9.10.2-P4.orig/bin/dig/dighost.c +++ bind-9.10.2-P4/bin/dig/dighost.c @@ -3349,6 +3349,7 @@ process_opt(dig_lookup_t *l, dns_message isc_buffer_t optbuf; isc_uint16_t optcode, optlen; dns_rdataset_t *opt = msg->opt; + isc_boolean_t seen_cookie = ISC_FALSE; result = dns_rdataset_first(opt); if (result == ISC_R_SUCCESS) { @@ -3360,8 +3361,16 @@ process_opt(dig_lookup_t *l, dns_message optcode = isc_buffer_getuint16(&optbuf); optlen = isc_buffer_getuint16(&optbuf); switch (optcode) { - case DNS_OPT_SIT: + case DNS_OPT_SIT: + /* + * Only process the first cookie option. + */ + if (seen_cookie) { + isc_buffer_forward(&optbuf, optlen); + break; + } process_sit(l, msg, &optbuf, optlen); + seen_cookie = ISC_TRUE; break; default: isc_buffer_forward(&optbuf, optlen); Index: bind-9.10.2-P4/bin/named/client.c =================================================================== --- bind-9.10.2-P4.orig/bin/named/client.c +++ bind-9.10.2-P4/bin/named/client.c @@ -121,7 +121,10 @@ */ #endif -#define SIT_SIZE 24U /* 8 + 4 + 4 + 8 */ +#define COOKIE_SIZE 24U /* 8 + 4 + 4 + 8 */ + +#define WANTNSID(x) (((x)->attributes & NS_CLIENTATTR_WANTNSID) != 0) +#define WANTEXPIRE(x) (((x)->attributes & NS_CLIENTATTR_WANTEXPIRE) != 0) /*% nameserver client manager structure */ struct ns_clientmgr { @@ -1391,7 +1394,7 @@ ns_client_addopt(ns_client_t *client, dn { char nsid[BUFSIZ], *nsidp; #ifdef ISC_PLATFORM_USESIT - unsigned char sit[SIT_SIZE]; + unsigned char sit[COOKIE_SIZE]; #endif isc_result_t result; dns_view_t *view; @@ -1416,7 +1419,7 @@ ns_client_addopt(ns_client_t *client, dn flags = client->extflags & DNS_MESSAGEEXTFLAG_REPLYPRESERVE; /* Set EDNS options if applicable */ - if ((client->attributes & NS_CLIENTATTR_WANTNSID) != 0 && + if (WANTNSID(client) && (ns_g_server->server_id != NULL || ns_g_server->server_usehostname)) { if (ns_g_server->server_usehostname) { @@ -1449,7 +1452,7 @@ ns_client_addopt(ns_client_t *client, dn INSIST(count < DNS_EDNSOPTIONS); ednsopts[count].code = DNS_OPT_SIT; - ednsopts[count].length = SIT_SIZE; + ednsopts[count].length = COOKIE_SIZE; ednsopts[count].value = sit; count++; } @@ -1657,19 +1660,26 @@ compute_sit(ns_client_t *client, isc_uin static void process_sit(ns_client_t *client, isc_buffer_t *buf, size_t optlen) { - unsigned char dbuf[SIT_SIZE]; + unsigned char dbuf[COOKIE_SIZE]; unsigned char *old; isc_stdtime_t now; isc_uint32_t when; isc_uint32_t nonce; isc_buffer_t db; + /* + * If we have already seen a ECS option skip this ECS option. + */ + if ((client->attributes & NS_CLIENTATTR_WANTSIT) != 0) { + isc_buffer_forward(buf, optlen); + return; + } client->attributes |= NS_CLIENTATTR_WANTSIT; isc_stats_increment(ns_g_server->nsstats, dns_nsstatscounter_sitopt); - if (optlen != SIT_SIZE) { + if (optlen != COOKIE_SIZE) { /* * Not our token. */ @@ -1713,7 +1723,7 @@ process_sit(ns_client_t *client, isc_buf isc_buffer_init(&db, dbuf, sizeof(dbuf)); compute_sit(client, when, nonce, &db); - if (memcmp(old, dbuf, SIT_SIZE) != 0) { + if (memcmp(old, dbuf, COOKIE_SIZE) != 0) { isc_stats_increment(ns_g_server->nsstats, dns_nsstatscounter_sitnomatch); return; @@ -1779,7 +1789,9 @@ process_opt(ns_client_t *client, dns_rda optlen = isc_buffer_getuint16(&optbuf); switch (optcode) { case DNS_OPT_NSID: - isc_stats_increment(ns_g_server->nsstats, + if (!WANTNSID(client)) + isc_stats_increment( + ns_g_server->nsstats, dns_nsstatscounter_nsidopt); client->attributes |= NS_CLIENTATTR_WANTNSID; isc_buffer_forward(&optbuf, optlen); @@ -1790,7 +1802,9 @@ process_opt(ns_client_t *client, dns_rda break; #endif case DNS_OPT_EXPIRE: - isc_stats_increment(ns_g_server->nsstats, + if (!WANTEXPIRE(client)) + isc_stats_increment( + ns_g_server->nsstats, dns_nsstatscounter_expireopt); client->attributes |= NS_CLIENTATTR_WANTEXPIRE; isc_buffer_forward(&optbuf, optlen); Index: bind-9.10.2-P4/lib/dns/resolver.c =================================================================== --- bind-9.10.2-P4.orig/lib/dns/resolver.c +++ bind-9.10.2-P4/lib/dns/resolver.c @@ -7144,7 +7144,9 @@ process_opt(resquery_t *query, dns_rdata unsigned char *sit; dns_adbaddrinfo_t *addrinfo; unsigned char cookie[8]; + isc_boolean_t seen_cookie = ISC_FALSE; #endif + isc_boolean_t seen_nsid = ISC_FALSE; result = dns_rdataset_first(opt); if (result == ISC_R_SUCCESS) { @@ -7158,14 +7160,23 @@ process_opt(resquery_t *query, dns_rdata INSIST(optlen <= isc_buffer_remaininglength(&optbuf)); switch (optcode) { case DNS_OPT_NSID: - if (query->options & DNS_FETCHOPT_WANTNSID) + if (!seen_nsid && + query->options & DNS_FETCHOPT_WANTNSID) log_nsid(&optbuf, optlen, query, ISC_LOG_DEBUG(3), query->fctx->res->mctx); isc_buffer_forward(&optbuf, optlen); + seen_nsid = ISC_TRUE; break; #ifdef ISC_PLATFORM_USESIT case DNS_OPT_SIT: + /* + * Only process the first cookie option. + */ + if (seen_cookie) { + isc_buffer_forward(&optbuf, optlen); + break; + } sit = isc_buffer_current(&optbuf); compute_cc(query, cookie, sizeof(cookie)); INSIST(query->fctx->rmessage->sitbad == 0 && @@ -7183,6 +7194,7 @@ process_opt(resquery_t *query, dns_rdata isc_buffer_forward(&optbuf, optlen); inc_stats(query->fctx->res, dns_resstatscounter_sitin); + seen_cookie = ISC_TRUE; break; #endif default: