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117 lines
3.9 KiB
117 lines
3.9 KiB
2 years ago
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From 3bcd32572504ac9b92e3c6ec1e2cee3df3b68309 Mon Sep 17 00:00:00 2001
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From: Petr Mensik <pemensik@redhat.com>
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Date: Tue, 20 Sep 2022 11:34:42 +0200
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Subject: [PATCH 2/4] Fix CVE-2022-3080
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5960. [security] Fix serve-stale crash that could happen when
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stale-answer-client-timeout was set to 0 and there was
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a stale CNAME in the cache for an incoming query.
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(CVE-2022-3080) [GL #3517]
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---
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lib/ns/include/ns/query.h | 1 +
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lib/ns/query.c | 42 ++++++++++++++++++++++++---------------
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2 files changed, 27 insertions(+), 16 deletions(-)
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diff --git a/lib/ns/include/ns/query.h b/lib/ns/include/ns/query.h
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index 4d48cf6..34b3070 100644
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--- a/lib/ns/include/ns/query.h
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+++ b/lib/ns/include/ns/query.h
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@@ -145,6 +145,7 @@ struct query_ctx {
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bool authoritative; /* authoritative query? */
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bool want_restart; /* CNAME chain or other
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* restart needed */
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+ bool refresh_rrset; /* stale RRset refresh needed */
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bool need_wildcardproof; /* wildcard proof needed */
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bool nxrewrite; /* negative answer from RPZ */
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bool findcoveringnsec; /* lookup covering NSEC */
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diff --git a/lib/ns/query.c b/lib/ns/query.c
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index 249321c..a450cb7 100644
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--- a/lib/ns/query.c
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+++ b/lib/ns/query.c
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@@ -5686,7 +5686,6 @@ query_lookup(query_ctx_t *qctx) {
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bool dbfind_stale = false;
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bool stale_timeout = false;
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bool stale_found = false;
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- bool refresh_rrset = false;
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bool stale_refresh_window = false;
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CCTRACE(ISC_LOG_DEBUG(3), "query_lookup");
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@@ -5868,8 +5867,7 @@ query_lookup(query_ctx_t *qctx) {
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"%s stale answer used, an attempt to "
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"refresh the RRset will still be made",
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namebuf);
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- refresh_rrset = STALE(qctx->rdataset);
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- qctx->client->nodetach = refresh_rrset;
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+ qctx->refresh_rrset = STALE(qctx->rdataset);
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}
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} else {
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/*
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@@ -5907,17 +5905,6 @@ query_lookup(query_ctx_t *qctx) {
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result = query_gotanswer(qctx, result);
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- if (refresh_rrset) {
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- /*
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- * If we reached this point then it means that we have found a
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- * stale RRset entry in cache and BIND is configured to allow
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- * queries to be answered with stale data if no active RRset
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- * is available, i.e. "stale-anwer-client-timeout 0". But, we
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- * still need to refresh the RRset.
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- */
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- query_refresh_rrset(qctx);
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- }
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-
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cleanup:
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return (result);
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}
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@@ -7737,11 +7724,14 @@ query_addanswer(query_ctx_t *qctx) {
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/*
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* On normal lookups, clear any rdatasets that were added on a
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- * lookup due to stale-answer-client-timeout.
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+ * lookup due to stale-answer-client-timeout. Do not clear if we
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+ * are going to refresh the RRset, because the stale contents are
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+ * prioritized.
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*/
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if (QUERY_STALEOK(&qctx->client->query) &&
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- !QUERY_STALETIMEOUT(&qctx->client->query))
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+ !QUERY_STALETIMEOUT(&qctx->client->query) && !qctx->refresh_rrset)
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{
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+ CCTRACE(ISC_LOG_DEBUG(3), "query_clear_stale");
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query_clear_stale(qctx->client);
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/*
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* We can clear the attribute to prevent redundant clearing
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@@ -11457,9 +11447,29 @@ ns_query_done(query_ctx_t *qctx) {
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/*
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* Client may have been detached after query_send(), so
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* we test and store the flag state here, for safety.
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+ * If we are refreshing the RRSet, we must not detach from the client
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+ * in the query_send(), so we need to override the flag.
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*/
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+ if (qctx->refresh_rrset) {
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+ qctx->client->nodetach = true;
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+ }
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nodetach = qctx->client->nodetach;
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query_send(qctx->client);
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+
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+ if (qctx->refresh_rrset) {
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+ /*
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+ * If we reached this point then it means that we have found a
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+ * stale RRset entry in cache and BIND is configured to allow
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+ * queries to be answered with stale data if no active RRset
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+ * is available, i.e. "stale-anwer-client-timeout 0". But, we
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+ * still need to refresh the RRset. To prevent adding duplicate
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+ * RRsets, clear the RRsets from the message before doing the
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+ * refresh.
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+ */
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+ message_clearrdataset(qctx->client->message, 0);
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+ query_refresh_rrset(qctx);
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+ }
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+
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if (!nodetach) {
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qctx->detach_client = true;
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}
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--
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2.37.3
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