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Prevent increased CPU consumption in DNSSEC validator

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KeyTrap - Extreme CPU consumption in DNSSEC validator. Preparing an
NSEC3 closest encloser proof can exhaust CPU resources.

6322.	[security]	Specific DNS answers could cause a denial-of-service
			condition due to DNS validation taking a long time.
			(CVE-2023-50387) [GL #4424]

Resolves: RHEL-25403 RHEL-25392
; Resolves: CVE-2023-50868 CVE-2023-50387
This commit is contained in:
Petr Menšík 2024-02-12 21:19:31 +01:00
parent 2c1332b473
commit 329c53c51c
2 changed files with 482 additions and 0 deletions
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478
bind-9.16-CVE-2023-50387.patch Normal file
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@ -0,0 +1,478 @@
From c6e05ffc5fb784514ab54938867abaab41126c65 Mon Sep 17 00:00:00 2001
From: Petr Mensik <pemensik@redhat.com>
Date: Mon, 12 Feb 2024 21:09:51 +0100
Subject: [PATCH] Prevent increased CPU consumption in DNSSEC validator
KeyTrap - Extreme CPU consumption in DNSSEC validator. Preparing an
NSEC3 closest encloser proof can exhaust CPU resources.
6322. [security] Specific DNS answers could cause a denial-of-service
condition due to DNS validation taking a long time.
(CVE-2023-50387) [GL #4424]
Resolves: CVE-2023-50387 CVE-2023-50868
---
lib/dns/dst_api.c | 27 +++++++++----
lib/dns/include/dns/validator.h | 1 +
lib/dns/include/dst/dst.h | 4 ++
lib/dns/resolver.c | 4 +-
lib/dns/validator.c | 67 +++++++++++++++------------------
lib/isc/include/isc/netmgr.h | 3 ++
lib/isc/netmgr/netmgr-int.h | 1 +
lib/isc/netmgr/netmgr.c | 36 +++++++++++-------
lib/isc/netmgr/tcp.c | 6 +--
lib/isc/netmgr/tcpdns.c | 4 +-
lib/isc/netmgr/udp.c | 6 +--
11 files changed, 91 insertions(+), 68 deletions(-)
diff --git a/lib/dns/dst_api.c b/lib/dns/dst_api.c
index 62600dd..3aafd7c 100644
--- a/lib/dns/dst_api.c
+++ b/lib/dns/dst_api.c
@@ -160,7 +160,8 @@ computeid(dst_key_t *key);
static isc_result_t
frombuffer(const dns_name_t *name, unsigned int alg, unsigned int flags,
unsigned int protocol, dns_rdataclass_t rdclass,
- isc_buffer_t *source, isc_mem_t *mctx, dst_key_t **keyp);
+ isc_buffer_t *source, isc_mem_t *mctx, bool no_rdata,
+ dst_key_t **keyp);
static isc_result_t
algorithm_status(unsigned int alg);
@@ -745,6 +746,13 @@ dst_key_todns(const dst_key_t *key, isc_buffer_t *target) {
isc_result_t
dst_key_fromdns(const dns_name_t *name, dns_rdataclass_t rdclass,
isc_buffer_t *source, isc_mem_t *mctx, dst_key_t **keyp) {
+ return (dst_key_fromdns_ex(name, rdclass, source, mctx, false, keyp));
+}
+
+isc_result_t
+dst_key_fromdns_ex(const dns_name_t *name, dns_rdataclass_t rdclass,
+ isc_buffer_t *source, isc_mem_t *mctx, bool no_rdata,
+ dst_key_t **keyp) {
uint8_t alg, proto;
uint32_t flags, extflags;
dst_key_t *key = NULL;
@@ -775,7 +783,7 @@ dst_key_fromdns(const dns_name_t *name, dns_rdataclass_t rdclass,
}
result = frombuffer(name, alg, flags, proto, rdclass, source, mctx,
- &key);
+ no_rdata, &key);
if (result != ISC_R_SUCCESS) {
return (result);
}
@@ -796,7 +804,7 @@ dst_key_frombuffer(const dns_name_t *name, unsigned int alg, unsigned int flags,
REQUIRE(dst_initialized);
result = frombuffer(name, alg, flags, protocol, rdclass, source, mctx,
- &key);
+ false, &key);
if (result != ISC_R_SUCCESS) {
return (result);
}
@@ -2288,7 +2296,8 @@ computeid(dst_key_t *key) {
static isc_result_t
frombuffer(const dns_name_t *name, unsigned int alg, unsigned int flags,
unsigned int protocol, dns_rdataclass_t rdclass,
- isc_buffer_t *source, isc_mem_t *mctx, dst_key_t **keyp) {
+ isc_buffer_t *source, isc_mem_t *mctx, bool no_rdata,
+ dst_key_t **keyp) {
dst_key_t *key;
isc_result_t ret;
@@ -2313,10 +2322,12 @@ frombuffer(const dns_name_t *name, unsigned int alg, unsigned int flags,
return (DST_R_UNSUPPORTEDALG);
}
- ret = key->func->fromdns(key, source);
- if (ret != ISC_R_SUCCESS) {
- dst_key_free(&key);
- return (ret);
+ if (!no_rdata) {
+ ret = key->func->fromdns(key, source);
+ if (ret != ISC_R_SUCCESS) {
+ dst_key_free(&key);
+ return (ret);
+ }
}
}
diff --git a/lib/dns/include/dns/validator.h b/lib/dns/include/dns/validator.h
index 4744014..fe97e41 100644
--- a/lib/dns/include/dns/validator.h
+++ b/lib/dns/include/dns/validator.h
@@ -148,6 +148,7 @@ struct dns_validator {
unsigned int authcount;
unsigned int authfail;
isc_stdtime_t start;
+ bool failed;
};
/*%
diff --git a/lib/dns/include/dst/dst.h b/lib/dns/include/dst/dst.h
index f454ebb..36770b5 100644
--- a/lib/dns/include/dst/dst.h
+++ b/lib/dns/include/dst/dst.h
@@ -469,6 +469,10 @@ dst_key_tofile(const dst_key_t *key, int type, const char *directory);
*/
isc_result_t
+dst_key_fromdns_ex(const dns_name_t *name, dns_rdataclass_t rdclass,
+ isc_buffer_t *source, isc_mem_t *mctx, bool no_rdata,
+ dst_key_t **keyp);
+isc_result_t
dst_key_fromdns(const dns_name_t *name, dns_rdataclass_t rdclass,
isc_buffer_t *source, isc_mem_t *mctx, dst_key_t **keyp);
/*%<
diff --git a/lib/dns/resolver.c b/lib/dns/resolver.c
index 7cbfbb2..be1d735 100644
--- a/lib/dns/resolver.c
+++ b/lib/dns/resolver.c
@@ -10613,8 +10613,8 @@ dns_resolver_create(dns_view_t *view, isc_taskmgr_t *taskmgr,
* Since we have a pool of tasks we bind them to task queues
* to spread the load evenly
*/
- result = isc_task_create_bound(taskmgr, 0,
- &res->buckets[i].task, i);
+ result = isc_task_create_bound(
+ taskmgr, 0, &res->buckets[i].task, ISC_NM_TASK_SLOW(i));
if (result != ISC_R_SUCCESS) {
isc_mutex_destroy(&res->buckets[i].lock);
goto cleanup_buckets;
diff --git a/lib/dns/validator.c b/lib/dns/validator.c
index e54fc70..e416cc9 100644
--- a/lib/dns/validator.c
+++ b/lib/dns/validator.c
@@ -1098,8 +1098,8 @@ create_validator(dns_validator_t *val, dns_name_t *name, dns_rdatatype_t type,
* 'rdataset'. If found, build a dst_key_t for it and point val->key at
* it.
*
- * If val->key is already non-NULL, locate it in the rdataset and then
- * search past it for the *next* key that could have signed 'siginfo', then
+ * If val->key is already non-NULL, start searching from the next position in
+ * 'rdataset' to find the *next* key that could have signed 'siginfo', then
* set val->key to that.
*
* Returns ISC_R_SUCCESS if a possible matching key has been found,
@@ -1112,59 +1112,59 @@ select_signing_key(dns_validator_t *val, dns_rdataset_t *rdataset) {
isc_buffer_t b;
dns_rdata_t rdata = DNS_RDATA_INIT;
dst_key_t *oldkey = val->key;
- bool foundold;
+ bool no_rdata = false;
if (oldkey == NULL) {
- foundold = true;
+ result = dns_rdataset_first(rdataset);
} else {
- foundold = false;
+ dst_key_free(&oldkey);
val->key = NULL;
+ result = dns_rdataset_next(rdataset);
}
-
- result = dns_rdataset_first(rdataset);
if (result != ISC_R_SUCCESS) {
- goto failure;
+ goto done;
}
+
do {
dns_rdataset_current(rdataset, &rdata);
isc_buffer_init(&b, rdata.data, rdata.length);
isc_buffer_add(&b, rdata.length);
INSIST(val->key == NULL);
- result = dst_key_fromdns(&siginfo->signer, rdata.rdclass, &b,
- val->view->mctx, &val->key);
+ result = dst_key_fromdns_ex(&siginfo->signer, rdata.rdclass, &b,
+ val->view->mctx, no_rdata,
+ &val->key);
if (result == ISC_R_SUCCESS) {
if (siginfo->algorithm ==
(dns_secalg_t)dst_key_alg(val->key) &&
siginfo->keyid ==
(dns_keytag_t)dst_key_id(val->key) &&
+ (dst_key_flags(val->key) & DNS_KEYFLAG_REVOKE) ==
+ 0 &&
dst_key_iszonekey(val->key))
{
- if (foundold) {
- /*
- * This is the key we're looking for.
- */
- return (ISC_R_SUCCESS);
- } else if (dst_key_compare(oldkey, val->key)) {
- foundold = true;
- dst_key_free(&oldkey);
+ if (no_rdata) {
+ /* Retry with full key */
+ dns_rdata_reset(&rdata);
+ dst_key_free(&val->key);
+ no_rdata = false;
+ continue;
}
+ /* This is the key we're looking for. */
+ goto done;
}
dst_key_free(&val->key);
}
dns_rdata_reset(&rdata);
result = dns_rdataset_next(rdataset);
+ no_rdata = true;
} while (result == ISC_R_SUCCESS);
+done:
if (result == ISC_R_NOMORE) {
result = ISC_R_NOTFOUND;
}
-failure:
- if (oldkey != NULL) {
- dst_key_free(&oldkey);
- }
-
return (result);
}
@@ -1557,20 +1557,9 @@ validate_answer(dns_validator_t *val, bool resume) {
continue;
}
- do {
- isc_result_t tresult;
- vresult = verify(val, val->key, &rdata,
- val->siginfo->keyid);
- if (vresult == ISC_R_SUCCESS) {
- break;
- }
-
- tresult = select_signing_key(val, val->keyset);
- if (tresult != ISC_R_SUCCESS) {
- break;
- }
- } while (1);
+ vresult = verify(val, val->key, &rdata, val->siginfo->keyid);
if (vresult != ISC_R_SUCCESS) {
+ val->failed = true;
validator_log(val, ISC_LOG_DEBUG(3),
"failed to verify rdataset");
} else {
@@ -1607,9 +1596,13 @@ validate_answer(dns_validator_t *val, bool resume) {
} else {
validator_log(val, ISC_LOG_DEBUG(3),
"verify failure: %s",
- isc_result_totext(result));
+ isc_result_totext(vresult));
resume = false;
}
+ if (val->failed) {
+ result = ISC_R_NOMORE;
+ break;
+ }
}
if (result != ISC_R_NOMORE) {
validator_log(val, ISC_LOG_DEBUG(3),
diff --git a/lib/isc/include/isc/netmgr.h b/lib/isc/include/isc/netmgr.h
index be9fd56..dfabdc8 100644
--- a/lib/isc/include/isc/netmgr.h
+++ b/lib/isc/include/isc/netmgr.h
@@ -455,6 +455,9 @@ isc_nm_tcpdnsconnect(isc_nm_t *mgr, isc_sockaddr_t *local, isc_sockaddr_t *peer,
* 'cb'.
*/
+#define ISC_NM_TASK_SLOW_OFFSET -2
+#define ISC_NM_TASK_SLOW(i) (ISC_NM_TASK_SLOW_OFFSET - 1 - i)
+
void
isc_nm_task_enqueue(isc_nm_t *mgr, isc_task_t *task, int threadid);
/*%<
diff --git a/lib/isc/netmgr/netmgr-int.h b/lib/isc/netmgr/netmgr-int.h
index f7b54f9..70bb32d 100644
--- a/lib/isc/netmgr/netmgr-int.h
+++ b/lib/isc/netmgr/netmgr-int.h
@@ -673,6 +673,7 @@ struct isc_nm {
#ifdef NETMGR_TRACE
ISC_LIST(isc_nmsocket_t) active_sockets;
#endif
+ int nlisteners;
};
typedef enum isc_nmsocket_type {
diff --git a/lib/isc/netmgr/netmgr.c b/lib/isc/netmgr/netmgr.c
index 0ed3182..898de41 100644
--- a/lib/isc/netmgr/netmgr.c
+++ b/lib/isc/netmgr/netmgr.c
@@ -269,31 +269,34 @@ isc__nm_winsock_destroy(void) {
#endif /* WIN32 */
static void
-isc__nm_threadpool_initialize(uint32_t workers) {
+isc__nm_threadpool_initialize(uint32_t nworkers) {
char buf[11];
int r = uv_os_getenv("UV_THREADPOOL_SIZE", buf,
&(size_t){ sizeof(buf) });
if (r == UV_ENOENT) {
- snprintf(buf, sizeof(buf), "%" PRIu32, workers);
+ snprintf(buf, sizeof(buf), "%" PRIu32, nworkers);
uv_os_setenv("UV_THREADPOOL_SIZE", buf);
}
}
void
-isc__netmgr_create(isc_mem_t *mctx, uint32_t workers, isc_nm_t **netmgrp) {
+isc__netmgr_create(isc_mem_t *mctx, uint32_t nworkers, isc_nm_t **netmgrp) {
isc_nm_t *mgr = NULL;
char name[32];
- REQUIRE(workers > 0);
+ REQUIRE(nworkers > 0);
#ifdef WIN32
isc__nm_winsock_initialize();
#endif /* WIN32 */
- isc__nm_threadpool_initialize(workers);
+ isc__nm_threadpool_initialize(nworkers);
mgr = isc_mem_get(mctx, sizeof(*mgr));
- *mgr = (isc_nm_t){ .nworkers = workers };
+ *mgr = (isc_nm_t){
+ .nworkers = nworkers * 2,
+ .nlisteners = nworkers,
+ };
isc_mem_attach(mctx, &mgr->mctx);
isc_mutex_init(&mgr->lock);
@@ -334,11 +337,12 @@ isc__netmgr_create(isc_mem_t *mctx, uint32_t workers, isc_nm_t **netmgrp) {
isc_mempool_associatelock(mgr->evpool, &mgr->evlock);
isc_mempool_setfillcount(mgr->evpool, 32);
- isc_barrier_init(&mgr->pausing, workers);
- isc_barrier_init(&mgr->resuming, workers);
+ isc_barrier_init(&mgr->pausing, mgr->nworkers);
+ isc_barrier_init(&mgr->resuming, mgr->nworkers);
- mgr->workers = isc_mem_get(mctx, workers * sizeof(isc__networker_t));
- for (size_t i = 0; i < workers; i++) {
+ mgr->workers = isc_mem_get(mctx,
+ mgr->nworkers * sizeof(isc__networker_t));
+ for (int i = 0; i < mgr->nworkers; i++) {
int r;
isc__networker_t *worker = &mgr->workers[i];
*worker = (isc__networker_t){
@@ -373,7 +377,7 @@ isc__netmgr_create(isc_mem_t *mctx, uint32_t workers, isc_nm_t **netmgrp) {
mgr->workers_running++;
isc_thread_create(nm_thread, &mgr->workers[i], &worker->thread);
- snprintf(name, sizeof(name), "isc-net-%04zu", i);
+ snprintf(name, sizeof(name), "isc-net-%04d", i);
isc_thread_setname(worker->thread, name);
}
@@ -848,9 +852,15 @@ isc_nm_task_enqueue(isc_nm_t *nm, isc_task_t *task, int threadid) {
isc__networker_t *worker = NULL;
if (threadid == -1) {
- tid = (int)isc_random_uniform(nm->nworkers);
+ tid = (int)isc_random_uniform(nm->nlisteners);
+ } else if (threadid == ISC_NM_TASK_SLOW_OFFSET) {
+ tid = nm->nlisteners +
+ (int)isc_random_uniform(nm->nworkers - nm->nlisteners);
+ } else if (threadid < ISC_NM_TASK_SLOW_OFFSET) {
+ tid = nm->nlisteners + (ISC_NM_TASK_SLOW(threadid) %
+ (nm->nworkers - nm->nlisteners));
} else {
- tid = threadid % nm->nworkers;
+ tid = threadid % nm->nlisteners;
}
worker = &nm->workers[tid];
diff --git a/lib/isc/netmgr/tcp.c b/lib/isc/netmgr/tcp.c
index 5cca9f5..83bd2e2 100644
--- a/lib/isc/netmgr/tcp.c
+++ b/lib/isc/netmgr/tcp.c
@@ -321,7 +321,7 @@ isc_nm_tcpconnect(isc_nm_t *mgr, isc_sockaddr_t *local, isc_sockaddr_t *peer,
isc__nm_connectcb(sock, req, result, false);
} else {
isc__nmsocket_clearcb(sock);
- sock->tid = isc_random_uniform(mgr->nworkers);
+ sock->tid = isc_random_uniform(mgr->nlisteners);
isc__nm_connectcb(sock, req, result, true);
}
atomic_store(&sock->closed, true);
@@ -339,7 +339,7 @@ isc_nm_tcpconnect(isc_nm_t *mgr, isc_sockaddr_t *local, isc_sockaddr_t *peer,
isc__nm_put_netievent_tcpconnect(mgr, ievent);
} else {
atomic_init(&sock->active, false);
- sock->tid = isc_random_uniform(mgr->nworkers);
+ sock->tid = isc_random_uniform(mgr->nlisteners);
isc__nm_enqueue_ievent(&mgr->workers[sock->tid],
(isc__netievent_t *)ievent);
}
@@ -435,7 +435,7 @@ isc_nm_listentcp(isc_nm_t *mgr, isc_sockaddr_t *iface,
#if defined(WIN32)
sock->nchildren = 1;
#else
- sock->nchildren = mgr->nworkers;
+ sock->nchildren = mgr->nlisteners;
#endif
children_size = sock->nchildren * sizeof(sock->children[0]);
sock->children = isc_mem_get(mgr->mctx, children_size);
diff --git a/lib/isc/netmgr/tcpdns.c b/lib/isc/netmgr/tcpdns.c
index 188790c..7f13ab2 100644
--- a/lib/isc/netmgr/tcpdns.c
+++ b/lib/isc/netmgr/tcpdns.c
@@ -305,7 +305,7 @@ isc_nm_tcpdnsconnect(isc_nm_t *mgr, isc_sockaddr_t *local, isc_sockaddr_t *peer,
isc__nm_put_netievent_tcpdnsconnect(mgr, ievent);
} else {
atomic_init(&sock->active, false);
- sock->tid = isc_random_uniform(mgr->nworkers);
+ sock->tid = isc_random_uniform(mgr->nlisteners);
isc__nm_enqueue_ievent(&mgr->workers[sock->tid],
(isc__netievent_t *)ievent);
}
@@ -404,7 +404,7 @@ isc_nm_listentcpdns(isc_nm_t *mgr, isc_sockaddr_t *iface,
#if defined(WIN32)
sock->nchildren = 1;
#else
- sock->nchildren = mgr->nworkers;
+ sock->nchildren = mgr->nlisteners;
#endif
children_size = sock->nchildren * sizeof(sock->children[0]);
sock->children = isc_mem_get(mgr->mctx, children_size);
diff --git a/lib/isc/netmgr/udp.c b/lib/isc/netmgr/udp.c
index a91c425..f2e161c 100644
--- a/lib/isc/netmgr/udp.c
+++ b/lib/isc/netmgr/udp.c
@@ -126,7 +126,7 @@ isc_nm_listenudp(isc_nm_t *mgr, isc_sockaddr_t *iface, isc_nm_recv_cb_t cb,
uv_os_sock_t fd = -1;
/*
- * We are creating mgr->nworkers duplicated sockets, one
+ * We are creating mgr->nlisteners duplicated sockets, one
* socket for each worker thread.
*/
sock = isc_mem_get(mgr->mctx, sizeof(isc_nmsocket_t));
@@ -136,7 +136,7 @@ isc_nm_listenudp(isc_nm_t *mgr, isc_sockaddr_t *iface, isc_nm_recv_cb_t cb,
#if defined(WIN32)
sock->nchildren = 1;
#else
- sock->nchildren = mgr->nworkers;
+ sock->nchildren = mgr->nlisteners;
#endif
children_size = sock->nchildren * sizeof(sock->children[0]);
@@ -795,7 +795,7 @@ isc_nm_udpconnect(isc_nm_t *mgr, isc_sockaddr_t *local, isc_sockaddr_t *peer,
isc__nm_put_netievent_udpconnect(mgr, event);
} else {
atomic_init(&sock->active, false);
- sock->tid = isc_random_uniform(mgr->nworkers);
+ sock->tid = isc_random_uniform(mgr->nlisteners);
isc__nm_enqueue_ievent(&mgr->workers[sock->tid],
(isc__netievent_t *)event);
}
--
2.43.0

4
bind9.16.spec
View File

@ -133,6 +133,7 @@ Patch194: bind-9.16-CVE-2023-4408.patch
Patch195: bind-9.16-CVE-2023-5517.patch
Patch196: bind-9.16-CVE-2023-5679.patch
Patch197: bind-9.16-CVE-2023-6516.patch
Patch198: bind-9.16-CVE-2023-50387.patch
%{?systemd_ordering}
Requires: coreutils
@ -450,6 +451,7 @@ in HTML and PDF format.
%patch195 -p1 -b .CVE-2023-5517
%patch196 -p1 -b .CVE-2023-5679
%patch197 -p1 -b .CVE-2023-6516
%patch198 -p1 -b .CVE-2023-50387
%if %{with PKCS11}
%patch135 -p1 -b .config-pkcs11
@ -1176,6 +1178,8 @@ fi;
- Prevent assertion failure if DNS64 and serve-stale is used (CVE-2023-5679)
- Specific recursive query patterns may lead to an out-of-memory
condition (CVE-2023-6516)
- Prevent increased CPU consumption in DNSSEC validator (CVE-2023-50387
CVE-2023-50868)
* Wed Sep 20 2023 Petr Menšík <pemensik@redhat.com> - 32:9.16.23-0.16
- Limit the amount of recursion possible in control channel (CVE-2023-3341)