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Code Issues Releases Wiki Activity

3241. [bug] Address race conditions in the resolver code.

Browse Source 
[RT #26889]
This commit is contained in:
Mark Andrews 2011-12-07 23:08:42 +00:00
parent 71e4c3ee74
commit e4aac0596c
2 changed files with 66 additions and 50 deletions
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3
CHANGES
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@ -1,3 +1,6 @@
3241. [bug] Address race conditions in the resolver code.
[RT #26889]
3240. [bug] DNSKEY state change events could be missed. [RT #26874]
3239. [bug] dns_dnssec_findmatchingkeys needs to use a consistent

113
lib/dns/resolver.c
View File

@ -15,7 +15,7 @@
* PERFORMANCE OF THIS SOFTWARE.
*/
/* $Id: resolver.c,v 1.445 2011/12/05 17:27:16 each Exp $ */
/* $Id: resolver.c,v 1.446 2011/12/07 23:08:42 marka Exp $ */
/*! \file */
@ -453,7 +453,7 @@ static isc_result_t ncache_adderesult(dns_message_t *message,
dns_rdataset_t *ardataset,
isc_result_t *eresultp);
static void validated(isc_task_t *task, isc_event_t *event);
static void maybe_destroy(fetchctx_t *fctx, isc_boolean_t locked);
static isc_boolean_t maybe_destroy(fetchctx_t *fctx, isc_boolean_t locked);
static void add_bad(fetchctx_t *fctx, dns_adbaddrinfo_t *addrinfo,
isc_result_t reason, badnstype_t badtype);
@ -746,8 +746,11 @@ resquery_destroy(resquery_t **queryp) {
INSIST(query->tcpsocket == NULL);
query->fctx->nqueries--;
if (SHUTTINGDOWN(query->fctx))
maybe_destroy(query->fctx, ISC_FALSE); /* Locks bucket. */
if (SHUTTINGDOWN(query->fctx)) {
dns_resolver_t *res = query->fctx->res;
if (maybe_destroy(query->fctx, ISC_FALSE))
empty_bucket(res);
}
query->magic = 0;
isc_mem_put(query->mctx, query, sizeof(*query));
*queryp = NULL;
@ -2161,6 +2164,7 @@ fctx_finddone(isc_task_t *task, isc_event_t *event) {
isc_boolean_t want_try = ISC_FALSE;
isc_boolean_t want_done = ISC_FALSE;
isc_boolean_t bucket_empty = ISC_FALSE;
isc_boolean_t destroy = ISC_FALSE;
unsigned int bucketnum;
find = event->ev_sender;
@ -2172,6 +2176,9 @@ fctx_finddone(isc_task_t *task, isc_event_t *event) {
FCTXTRACE("finddone");
bucketnum = fctx->bucketnum;
LOCK(&res->buckets[bucketnum].lock);
INSIST(fctx->pending > 0);
fctx->pending--;
@ -2196,17 +2203,17 @@ fctx_finddone(isc_task_t *task, isc_event_t *event) {
}
} else if (SHUTTINGDOWN(fctx) && fctx->pending == 0 &&
fctx->nqueries == 0 && ISC_LIST_EMPTY(fctx->validators)) {
bucketnum = fctx->bucketnum;
LOCK(&res->buckets[bucketnum].lock);
/*
* Note that we had to wait until we had the lock before
* looking at fctx->references.
*/
if (fctx->references == 0)
bucket_empty = fctx_destroy(fctx);
UNLOCK(&res->buckets[bucketnum].lock);
destroy = ISC_TRUE;
}
UNLOCK(&res->buckets[bucketnum].lock);
if (destroy)
bucket_empty = fctx_destroy(fctx);
isc_event_free(&event);
dns_adb_destroyfind(&find);
@ -3889,13 +3896,15 @@ clone_results(fetchctx_t *fctx) {
/*
* Destroy '*fctx' if it is ready to be destroyed (i.e., if it has
* no references and is no longer waiting for any events). If this
* was the last fctx in the resolver, destroy the resolver.
* no references and is no longer waiting for any events).
*
* Requires:
* '*fctx' is shutting down.
*
* Returns:
* true if the resolver is exiting and this is the last fctx in the bucket.
*/
static void
static isc_boolean_t
maybe_destroy(fetchctx_t *fctx, isc_boolean_t locked) {
unsigned int bucketnum;
isc_boolean_t bucket_empty = ISC_FALSE;
@ -3904,8 +3913,11 @@ maybe_destroy(fetchctx_t *fctx, isc_boolean_t locked) {
REQUIRE(SHUTTINGDOWN(fctx));
bucketnum = fctx->bucketnum;
if (!locked)
LOCK(&res->buckets[bucketnum].lock);
if (fctx->pending != 0 || fctx->nqueries != 0)
return;
goto unlock;
for (validator = ISC_LIST_HEAD(fctx->validators);
validator != NULL; validator = next_validator) {
@ -3913,16 +3925,12 @@ maybe_destroy(fetchctx_t *fctx, isc_boolean_t locked) {
dns_validator_cancel(validator);
}
bucketnum = fctx->bucketnum;
if (!locked)
LOCK(&res->buckets[bucketnum].lock);
if (fctx->references == 0 && ISC_LIST_EMPTY(fctx->validators))
bucket_empty = fctx_destroy(fctx);
unlock:
if (!locked)
UNLOCK(&res->buckets[bucketnum].lock);
if (bucket_empty)
empty_bucket(res);
return (bucket_empty);
}
/*
@ -3930,31 +3938,33 @@ maybe_destroy(fetchctx_t *fctx, isc_boolean_t locked) {
*/
static void
validated(isc_task_t *task, isc_event_t *event) {
isc_result_t result = ISC_R_SUCCESS;
isc_result_t eresult = ISC_R_SUCCESS;
isc_stdtime_t now;
fetchctx_t *fctx;
dns_validatorevent_t *vevent;
dns_adbaddrinfo_t *addrinfo;
dns_dbnode_t *node = NULL;
dns_dbnode_t *nsnode = NULL;
dns_fetchevent_t *hevent;
dns_name_t *name;
dns_rdataset_t *ardataset = NULL;
dns_rdataset_t *asigrdataset = NULL;
dns_dbnode_t *node = NULL;
isc_boolean_t negative;
isc_boolean_t chaining;
isc_boolean_t sentresponse;
isc_uint32_t ttl;
dns_dbnode_t *nsnode = NULL;
dns_name_t *name;
dns_rdataset_t *rdataset;
dns_rdataset_t *sigrdataset;
dns_resolver_t *res;
dns_valarg_t *valarg;
dns_adbaddrinfo_t *addrinfo;
dns_validatorevent_t *vevent;
fetchctx_t *fctx;
isc_boolean_t chaining;
isc_boolean_t negative;
isc_boolean_t sentresponse;
isc_result_t eresult = ISC_R_SUCCESS;
isc_result_t result = ISC_R_SUCCESS;
isc_stdtime_t now;
isc_uint32_t ttl;
UNUSED(task); /* for now */
REQUIRE(event->ev_type == DNS_EVENT_VALIDATORDONE);
valarg = event->ev_arg;
fctx = valarg->fctx;
res = fctx->res;
addrinfo = valarg->addrinfo;
REQUIRE(VALID_FCTX(fctx));
REQUIRE(!ISC_LIST_EMPTY(fctx->validators));
@ -3964,7 +3974,7 @@ validated(isc_task_t *task, isc_event_t *event) {
FCTXTRACE("received validation completion event");
LOCK(&fctx->res->buckets[fctx->bucketnum].lock);
LOCK(&res->buckets[fctx->bucketnum].lock);
ISC_LIST_UNLINK(fctx->validators, vevent->validator, link);
fctx->validator = NULL;
@ -3974,7 +3984,7 @@ validated(isc_task_t *task, isc_event_t *event) {
* destroy the fctx if necessary.
*/
dns_validator_destroy(&vevent->validator);
isc_mem_put(fctx->res->buckets[fctx->bucketnum].mctx,
isc_mem_put(res->buckets[fctx->bucketnum].mctx,
valarg, sizeof(*valarg));
negative = ISC_TF(vevent->rdataset == NULL);
@ -3987,10 +3997,12 @@ validated(isc_task_t *task, isc_event_t *event) {
* so, destroy the fctx.
*/
if (SHUTTINGDOWN(fctx) && !sentresponse) {
isc_mutex_t *bucketlock =
&fctx->res->buckets[fctx->bucketnum].lock;
maybe_destroy(fctx, ISC_TRUE);
UNLOCK(bucketlock);
isc_uint32_t bucketnum = fctx->bucketnum;
isc_boolean_t bucket_empty;
bucket_empty = maybe_destroy(fctx, ISC_TRUE);
UNLOCK(&res->buckets[bucketnum].lock);
if (bucket_empty)
empty_bucket(res);
goto cleanup_event;
}
@ -4039,7 +4051,7 @@ validated(isc_task_t *task, isc_event_t *event) {
if (vevent->result != ISC_R_SUCCESS) {
FCTXTRACE("validation failed");
inc_stats(fctx->res, dns_resstatscounter_valfail);
inc_stats(res, dns_resstatscounter_valfail);
fctx->valfail++;
fctx->vresult = vevent->result;
if (fctx->vresult != DNS_R_BROKENCHAIN) {
@ -4088,7 +4100,7 @@ validated(isc_task_t *task, isc_event_t *event) {
result = fctx->vresult;
add_bad(fctx, addrinfo, result, badns_validation);
isc_event_free(&event);
UNLOCK(&fctx->res->buckets[fctx->bucketnum].lock);
UNLOCK(&res->buckets[fctx->bucketnum].lock);
INSIST(fctx->validator == NULL);
fctx->validator = ISC_LIST_HEAD(fctx->validators);
if (fctx->validator != NULL)
@ -4107,8 +4119,7 @@ validated(isc_task_t *task, isc_event_t *event) {
fctx->type == dns_rdatatype_dlv ||
fctx->type == dns_rdatatype_ds) &&
tresult == ISC_R_SUCCESS)
dns_resolver_addbadcache(fctx->res,
&fctx->name,
dns_resolver_addbadcache(res, &fctx->name,
fctx->type, &expire);
fctx_done(fctx, result, __LINE__); /* Locks bucket. */
} else
@ -4121,7 +4132,7 @@ validated(isc_task_t *task, isc_event_t *event) {
dns_rdatatype_t covers;
FCTXTRACE("nonexistence validation OK");
inc_stats(fctx->res, dns_resstatscounter_valnegsuccess);
inc_stats(res, dns_resstatscounter_valnegsuccess);
if (fctx->rmessage->rcode == dns_rcode_nxdomain)
covers = dns_rdatatype_any;
@ -4138,10 +4149,9 @@ validated(isc_task_t *task, isc_event_t *event) {
* to zero to facilitate locating the containing zone of
* a arbitrary zone.
*/
ttl = fctx->res->view->maxncachettl;
ttl = res->view->maxncachettl;
if (fctx->type == dns_rdatatype_soa &&
covers == dns_rdatatype_any &&
fctx->res->zero_no_soa_ttl)
covers == dns_rdatatype_any && res->zero_no_soa_ttl)
ttl = 0;
result = ncache_adderesult(fctx->rmessage, fctx->cache, node,
@ -4151,7 +4161,7 @@ validated(isc_task_t *task, isc_event_t *event) {
goto noanswer_response;
goto answer_response;
} else
inc_stats(fctx->res, dns_resstatscounter_valsuccess);
inc_stats(res, dns_resstatscounter_valsuccess);
FCTXTRACE("validation OK");
@ -4199,14 +4209,17 @@ validated(isc_task_t *task, isc_event_t *event) {
}
if (sentresponse) {
isc_boolean_t bucket_empty = ISC_FALSE;
/*
* If we only deferred the destroy because we wanted to cache
* the data, destroy now.
*/
dns_db_detachnode(fctx->cache, &node);
UNLOCK(&fctx->res->buckets[fctx->bucketnum].lock);
if (SHUTTINGDOWN(fctx))
maybe_destroy(fctx, ISC_FALSE); /* Locks bucket. */
bucket_empty = maybe_destroy(fctx, ISC_TRUE);
UNLOCK(&res->buckets[fctx->bucketnum].lock);
if (bucket_empty)
empty_bucket(res);
goto cleanup_event;
}
@ -4221,7 +4234,7 @@ validated(isc_task_t *task, isc_event_t *event) {
* be validated.
*/
dns_db_detachnode(fctx->cache, &node);
UNLOCK(&fctx->res->buckets[fctx->bucketnum].lock);
UNLOCK(&res->buckets[fctx->bucketnum].lock);
dns_validator_send(ISC_LIST_HEAD(fctx->validators));
goto cleanup_event;
}
@ -4296,7 +4309,7 @@ validated(isc_task_t *task, isc_event_t *event) {
if (node != NULL)
dns_db_detachnode(fctx->cache, &node);
UNLOCK(&fctx->res->buckets[fctx->bucketnum].lock);
UNLOCK(&res->buckets[fctx->bucketnum].lock);
fctx_done(fctx, result, __LINE__); /* Locks bucket. */
cleanup_event: