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Refactor the isc_quota code and fix the quota in TCP accept code

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In e185412872, the TCP accept quota code
became broken in a subtle way - the quota would get initialized on the
first accept for the server socket and then deleted from the server
socket, so it would never get applied again.

Properly fixing this required a bigger refactoring of the isc_quota API
code to make it much simpler.  The new code decouples the ownership of
the quota and acquiring/releasing the quota limit.

After (during) the refactoring it became more clear that we need to use
the callback from the child side of the accepted connection, and not the
server side.
This commit is contained in:
Ondřej Surý
2023-04-11 07:54:58 +02:00
parent 1768522045
commit 1715cad685
13 changed files with 210 additions and 433 deletions
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49
lib/ns/query.c
View File

@@ -2483,13 +2483,10 @@ free_fresp(ns_client_t *client, dns_fetchresponse_t **frespp) {
}
static isc_result_t
recursionquotatype_attach(ns_client_t *client,
ns_query_rectype_t recursion_type, bool soft_limit) {
isc_quota_t **quotap = &client->query.recursions[recursion_type].quota;
recursionquotatype_attach(ns_client_t *client, bool soft_limit) {
isc_result_t result;
result = isc_quota_attach(&client->manager->sctx->recursionquota,
quotap);
result = isc_quota_acquire(&client->manager->sctx->recursionquota);
switch (result) {
case ISC_R_SUCCESS:
break;
@@ -2503,7 +2500,7 @@ recursionquotatype_attach(ns_client_t *client,
break;
}
isc_quota_detach(quotap);
isc_quota_release(&client->manager->sctx->recursionquota);
FALLTHROUGH;
default:
return (result);
@@ -2516,21 +2513,18 @@ recursionquotatype_attach(ns_client_t *client,
}
static isc_result_t
recursionquotatype_attach_hard(ns_client_t *client,
ns_query_rectype_t recursion_type) {
return (recursionquotatype_attach(client, recursion_type, false));
recursionquotatype_attach_hard(ns_client_t *client) {
return (recursionquotatype_attach(client, false));
}
static isc_result_t
recursionquotatype_attach_soft(ns_client_t *client,
ns_query_rectype_t recursion_type) {
return (recursionquotatype_attach(client, recursion_type, true));
recursionquotatype_attach_soft(ns_client_t *client) {
return (recursionquotatype_attach(client, true));
}
static void
recursionquotatype_detach(ns_client_t *client,
ns_query_rectype_t recursion_type) {
isc_quota_detach(&client->query.recursions[recursion_type].quota);
recursionquotatype_detach(ns_client_t *client) {
isc_quota_release(&client->manager->sctx->recursionquota);
ns_stats_decrement(client->manager->sctx->nsstats,
ns_statscounter_recursclients);
}
@@ -2646,7 +2640,7 @@ cleanup_after_fetch(dns_fetchresponse_t *resp, const char *ctracestr,
stale_refresh_aftermath(client, result);
}
recursionquotatype_detach(client, recursion_type);
recursionquotatype_detach(client);
free_fresp(client, &resp);
isc_nmhandle_detach(handlep);
}
@@ -2685,7 +2679,7 @@ fetch_and_forget(ns_client_t *client, dns_name_t *qname, dns_rdatatype_t qtype,
dns_fetch_t **fetchp;
isc_result_t result;
result = recursionquotatype_attach_hard(client, recursion_type);
result = recursionquotatype_attach_hard(client);
if (result != ISC_R_SUCCESS) {
return;
}
@@ -2726,7 +2720,7 @@ fetch_and_forget(ns_client_t *client, dns_name_t *qname, dns_rdatatype_t qtype,
if (result != ISC_R_SUCCESS) {
ns_client_putrdataset(client, &tmprdataset);
isc_nmhandle_detach(handlep);
recursionquotatype_detach(client, recursion_type);
recursionquotatype_detach(client);
}
}
@@ -6299,7 +6293,7 @@ fetch_callback(void *arg) {
* the manager's recursing-clients list.
*/
recursionquotatype_detach(client, RECTYPE_NORMAL);
recursionquotatype_detach(client);
LOCK(&client->manager->reclock);
if (ISC_LINK_LINKED(client, rlink)) {
@@ -6431,17 +6425,16 @@ static atomic_uint_fast32_t last_soft, last_hard;
* Check recursion quota before making the current client "recursing".
*/
static isc_result_t
check_recursionquota(ns_client_t *client, ns_query_rectype_t recursion_type) {
isc_quota_t **quotap = &client->query.recursions[recursion_type].quota;
check_recursionquota(ns_client_t *client) {
isc_result_t result;
result = recursionquotatype_attach_soft(client, recursion_type);
result = recursionquotatype_attach_soft(client);
switch (result) {
case ISC_R_SOFTQUOTA:
recursionquota_log(client, &last_soft,
"recursive-clients soft limit exceeded "
"(%u/%u/%u), aborting oldest query",
*quotap);
&client->manager->sctx->recursionquota);
ns_client_killoldestquery(client);
FALLTHROUGH;
case ISC_R_SUCCESS:
@@ -6488,7 +6481,7 @@ ns_query_recurse(ns_client_t *client, dns_rdatatype_t qtype, dns_name_t *qname,
inc_stats(client, ns_statscounter_recursion);
}
result = check_recursionquota(client, RECTYPE_NORMAL);
result = check_recursionquota(client);
if (result != ISC_R_SUCCESS) {
return (result);
}
@@ -6534,7 +6527,7 @@ ns_query_recurse(ns_client_t *client, dns_rdatatype_t qtype, dns_name_t *qname,
if (sigrdataset != NULL) {
ns_client_putrdataset(client, &sigrdataset);
}
recursionquotatype_detach(client, RECTYPE_NORMAL);
recursionquotatype_detach(client);
}
/*
@@ -6764,7 +6757,7 @@ query_hookresume(void *arg) {
UNLOCK(&client->query.fetchlock);
SAVE(hctx, rev->ctx);
recursionquotatype_detach(client, RECTYPE_HOOK);
recursionquotatype_detach(client);
LOCK(&client->manager->reclock);
if (ISC_LINK_LINKED(client, rlink)) {
@@ -6895,7 +6888,7 @@ ns_query_hookasync(query_ctx_t *qctx, ns_query_starthookasync_t runasync,
REQUIRE(client->query.hookactx == NULL);
REQUIRE(FETCH_RECTYPE_NORMAL(client) == NULL);
result = check_recursionquota(client, RECTYPE_HOOK);
result = check_recursionquota(client);
if (result != ISC_R_SUCCESS) {
goto cleanup;
}
@@ -6924,7 +6917,7 @@ ns_query_hookasync(query_ctx_t *qctx, ns_query_starthookasync_t runasync,
return (ISC_R_SUCCESS);
cleanup_and_detach_from_quota:
recursionquotatype_detach(client, RECTYPE_HOOK);
recursionquotatype_detach(client);
cleanup:
/*
* If we fail, send SERVFAIL now. It may be better to let the caller