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bind/bind-9.16-CVE-2022-3094-1.patch
Petr Menšík 1d416c2d77 Prevent flooding with UPDATE requests 
6064.	[security]	An UPDATE message flood could cause named to exhaust all
			available memory. This flaw was addressed by adding a
			new "update-quota" statement that controls the number of
			simultaneous UPDATE messages that can be processed or
			forwarded. The default is 100. A stats counter has been
			added to record events when the update quota is
			exceeded, and the XML and JSON statistics version
			numbers have been updated. (CVE-2022-3094) [GL #3523]

Resolves: CVE-2022-3094
2023-03-30 19:41:23 +02:00

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From 128b3b676eb9413b4d25fb29c560895cfbbfa92e Mon Sep 17 00:00:00 2001
From: Evan Hunt <each@isc.org>
Date: Thu, 1 Sep 2022 16:05:04 -0700
Subject: [PATCH] add an update quota
limit the number of simultaneous DNS UPDATE events that can be
processed by adding a quota for update and update forwarding.
this quota currently, arbitrarily, defaults to 100.
also add a statistics counter to record when the update quota
has been exceeded.
(cherry picked from commit 7c47254a140c3e9cf383cda73c7b6a55c4782826)
---
bin/named/bind9.xsl | 2 +-
bin/named/bind9.xsl.h | 8 +++++++-
bin/named/include/named/server.h | 7 ++++++-
bin/named/server.c | 3 +++
bin/named/statschannel.c | 5 +++--
bin/named/update.c | 34 +++++++++++++++++++++++++++++++-
doc/arm/Bv9ARM-book.xml | 15 ++++++++++++++
7 files changed, 68 insertions(+), 6 deletions(-)
diff --git a/bin/named/bind9.xsl b/bin/named/bind9.xsl
index 9a1c6ff..85fd4c4 100644
--- a/bin/named/bind9.xsl
+++ b/bin/named/bind9.xsl
@@ -12,7 +12,7 @@
<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns="http://www.w3.org/1999/xhtml" version="1.0">
<xsl:output method="html" indent="yes" version="4.0"/>
- <xsl:template match="statistics[@version=&quot;3.8&quot;]">
+ <xsl:template match="statistics[@version=&quot;3.8.1&quot;]">
<html>
<head>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
diff --git a/bin/named/bind9.xsl.h b/bin/named/bind9.xsl.h
index 9ce8cd7..5e0a892 100644
--- a/bin/named/bind9.xsl.h
+++ b/bin/named/bind9.xsl.h
@@ -17,7 +17,13 @@ static char xslmsg[] =
"\n"
"<xsl:stylesheet xmlns:xsl=\"http://www.w3.org/1999/XSL/Transform\" xmlns=\"http://www.w3.org/1999/xhtml\" version=\"1.0\">\n"
" <xsl:output method=\"html\" indent=\"yes\" version=\"4.0\"/>\n"
- " <xsl:template match=\"statistics[@version=&quot;3.8&quot;]\">\n"
+#if 0
+ " <!-- the version number **below** must match version in "
+ "bin/named/statschannel.c -->\n"
+ " <!-- don't forget to update \"/xml/v<STATS_XML_VERSION_MAJOR>\" in "
+ "the HTTP endpoints listed below -->\n"
+#endif
+ " <xsl:template match=\"statistics[@version=&quot;3.8.1&quot;]\">\n"
" <html>\n"
" <head>\n"
" <script type=\"text/javascript\" src=\"https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js\"></script>\n"
diff --git a/bin/named/include/named/server.h b/bin/named/include/named/server.h
index 08a02dc..259acc7 100644
--- a/bin/named/include/named/server.h
+++ b/bin/named/include/named/server.h
@@ -137,6 +137,9 @@ struct ns_server {
uint16_t transfer_tcp_message_size;
isc_rng_t * rngctx;
+
+/* CVE-2022-3094 */
+ isc_quota_t updquota;
};
struct ns_altsecret {
@@ -230,7 +233,9 @@ enum {
dns_nsstatscounter_trystale = 59,
dns_nsstatscounter_usedstale = 60,
- dns_nsstatscounter_max = 61
+ dns_nsstatscounter_updatequota = 61,
+
+ dns_nsstatscounter_max = 62
};
/*%
diff --git a/bin/named/server.c b/bin/named/server.c
index 2d2fa0e..f09b895 100644
--- a/bin/named/server.c
+++ b/bin/named/server.c
@@ -9143,6 +9143,8 @@ ns_server_create(isc_mem_t *mctx, ns_server_t **serverp) {
RUNTIME_CHECK(result == ISC_R_SUCCESS);
result = isc_quota_init(&server->recursionquota, 100);
RUNTIME_CHECK(result == ISC_R_SUCCESS);
+ result = isc_quota_init(&server->updquota, 100);
+ RUNTIME_CHECK(result == ISC_R_SUCCESS);
result = dns_aclenv_init(mctx, &server->aclenv);
RUNTIME_CHECK(result == ISC_R_SUCCESS);
@@ -9410,6 +9412,7 @@ ns_server_destroy(ns_server_t **serverp) {
dns_aclenv_destroy(&server->aclenv);
+ isc_quota_destroy(&server->updquota);
isc_quota_destroy(&server->recursionquota);
isc_quota_destroy(&server->tcpquota);
isc_quota_destroy(&server->xfroutquota);
diff --git a/bin/named/statschannel.c b/bin/named/statschannel.c
index 56a9c21..1e8723c 100644
--- a/bin/named/statschannel.c
+++ b/bin/named/statschannel.c
@@ -300,6 +300,7 @@ init_desc(void) {
SET_NSSTATDESC(reclimitdropped,
"queries dropped due to recursive client limit",
"RecLimitDropped");
+ SET_NSSTATDESC(updatequota, "Update quota exceeded", "UpdateQuota");
SET_NSSTATDESC(trystale,
"attempts to use stale cache data after lookup failure",
"QryTryStale");
@@ -1546,7 +1547,7 @@ generatexml(ns_server_t *server, uint32_t flags,
ISC_XMLCHAR "type=\"text/xsl\" href=\"/bind9.xsl\""));
TRY0(xmlTextWriterStartElement(writer, ISC_XMLCHAR "statistics"));
TRY0(xmlTextWriterWriteAttribute(writer, ISC_XMLCHAR "version",
- ISC_XMLCHAR "3.8"));
+ ISC_XMLCHAR "3.8.1"));
/* Set common fields for statistics dump */
dumparg.type = isc_statsformat_xml;
@@ -2303,7 +2304,7 @@ generatejson(ns_server_t *server, size_t *msglen,
/*
* These statistics are included no matter which URL we use.
*/
- obj = json_object_new_string("1.2");
+ obj = json_object_new_string("1.2.1");
CHECKMEM(obj);
json_object_object_add(bindstats, "json-stats-version", obj);
diff --git a/bin/named/update.c b/bin/named/update.c
index 6ad7d27..dccc543 100644
--- a/bin/named/update.c
+++ b/bin/named/update.c
@@ -1526,6 +1526,17 @@ send_update_event(ns_client_t *client, dns_zone_t *zone) {
isc_task_t *zonetask = NULL;
ns_client_t *evclient;
+ result = isc_quota_attach(&ns_g_server->updquota,
+ &(isc_quota_t *){ NULL });
+ if (result != ISC_R_SUCCESS) {
+ update_log(client, zone, LOGLEVEL_PROTOCOL,
+ "update failed: too many DNS UPDATEs queued (%s)",
+ isc_result_totext(result));
+ isc_stats_increment(ns_g_server->nsstats,
+ dns_nsstatscounter_updatequota);
+ CHECK(DNS_R_DROP);
+ }
+
event = (update_event_t *)
isc_event_allocate(client->mctx, client, DNS_EVENT_UPDATE,
update_action, NULL, sizeof(*event));
@@ -1652,7 +1663,12 @@ ns_update_start(ns_client_t *client, isc_result_t sigresult) {
* We are still in the client task context, so we can
* simply give an error response without switching tasks.
*/
- respond(client, result);
+ if (result == DNS_R_DROP) {
+ ns_client_next(client, result);
+ } else {
+ respond(client, result);
+ }
+
if (zone != NULL)
dns_zone_detach(&zone);
}
@@ -3385,6 +3401,7 @@ updatedone_action(isc_task_t *task, isc_event_t *event) {
dns_zone_detach(&uev->zone);
client->nupdates--;
respond(client, uev->result);
+ isc_quota_detach(&(isc_quota_t *){ &ns_g_server->updquota });
isc_event_free(&event);
ns_client_detach(&client);
}
@@ -3402,6 +3419,8 @@ forward_fail(isc_task_t *task, isc_event_t *event) {
INSIST(client->nupdates > 0);
client->nupdates--;
respond(client, DNS_R_SERVFAIL);
+
+ isc_quota_detach(&(isc_quota_t *){ &ns_g_server->updquota });
isc_event_free(&event);
ns_client_detach(&client);
}
@@ -3439,6 +3458,8 @@ forward_done(isc_task_t *task, isc_event_t *event) {
client->nupdates--;
ns_client_sendraw(client, uev->answer);
dns_message_detach(&uev->answer);
+
+ isc_quota_detach(&(isc_quota_t *){ &ns_g_server->updquota });
isc_event_free(&event);
ns_client_detach(&client);
}
@@ -3472,6 +3493,17 @@ send_forward_event(ns_client_t *client, dns_zone_t *zone) {
isc_task_t *zonetask = NULL;
ns_client_t *evclient;
+ result = isc_quota_attach(&ns_g_server->updquota,
+ &(isc_quota_t *){ NULL });
+ if (result != ISC_R_SUCCESS) {
+ update_log(client, zone, LOGLEVEL_PROTOCOL,
+ "update failed: too many DNS UPDATEs queued (%s)",
+ isc_result_totext(result));
+ isc_stats_increment(ns_g_server->nsstats,
+ dns_nsstatscounter_updatequota);
+ return (DNS_R_DROP);
+ }
+
/*
* This may take some time so replace this client.
*/
diff --git a/doc/arm/Bv9ARM-book.xml b/doc/arm/Bv9ARM-book.xml
index c17f168..9aca6d7 100644
--- a/doc/arm/Bv9ARM-book.xml
+++ b/doc/arm/Bv9ARM-book.xml
@@ -15105,6 +15105,21 @@ HOST-127.EXAMPLE. MX 0 .
</para>
</entry>
</row>
+ <row rowsep="0">
+ <entry colname="1">
+ <para><command>UpdateQuota</command></para>
+ </entry>
+ <entry colname="2">
+ <para><command/></para>
+ </entry>
+ <entry colname="3">
+ <para>
+ This indicates the number of times a dynamic update or update
+ forwarding request was rejected because the number of pending
+ requests exceeded the update quota.
+ </para>
+ </entry>
+ </row>
<row rowsep="0">
<entry colname="1">
<para><command>RateDropped</command></para>
--
2.39.2
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