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From 10642f9fb350e118d88e995b8dfa2badc7be1c30 Mon Sep 17 00:00:00 2001
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From: Petr Mensik <pemensik@redhat.com>
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Date: Wed, 11 Dec 2019 13:41:57 +0100
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Subject: [PATCH] Restore ability to answer non-recursive requests
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Instead, check only local configured entries are answered without
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rdbit set. All cached replies are still denied, but locally configured
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names are available with both recursion and without it.
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---
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src/rfc1035.c | 27 ++++++++++++++-------------
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1 file changed, 14 insertions(+), 13 deletions(-)
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diff --git a/src/rfc1035.c b/src/rfc1035.c
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index 6b3bb27..6a7c154 100644
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--- a/src/rfc1035.c
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+++ b/src/rfc1035.c
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@@ -1262,7 +1262,11 @@ static unsigned long crec_ttl(struct crec *crecp, time_t now)
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else
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return daemon->max_ttl;
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}
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-
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+
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+static int cache_validated(const struct crec *crecp)
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+{
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+ return (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK));
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+}
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/* return zero if we can't answer from cache, or packet size if we can */
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size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
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@@ -1281,6 +1285,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
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int nxdomain = 0, auth = 1, trunc = 0, sec_data = 1;
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struct mx_srv_record *rec;
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size_t len;
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+ int rd_bit;
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// Make sure we do not underflow here too.
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if (qlen > (limit - ((char *)header))) return 0;
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@@ -1290,10 +1295,8 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
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OPCODE(header) != QUERY )
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return 0;
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- /* always servfail queries with RD unset, to avoid cache snooping. */
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- if (!(header->hb3 & HB3_RD))
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- return setup_reply(header, qlen, NULL, F_SERVFAIL, 0);
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-
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+ rd_bit = (header->hb3 & HB3_RD);
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+
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/* Don't return AD set if checking disabled. */
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if (header->hb4 & HB4_CD)
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sec_data = 0;
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@@ -1458,9 +1461,8 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
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/* Don't use cache when DNSSEC data required, unless we know that
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the zone is unsigned, which implies that we're doing
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validation. */
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- if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
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- !do_bit ||
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- (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK)))
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+ if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
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+ (rd_bit && (!do_bit || cache_validated(crecp)) ))
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{
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do
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{
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@@ -1657,8 +1659,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
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/* If the client asked for DNSSEC don't use cached data. */
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if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
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- !do_bit ||
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- (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK)))
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+ (rd_bit && (!do_bit || cache_validated(crecp)) ))
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do
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{
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/* don't answer wildcard queries with data not from /etc/hosts
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@@ -1741,8 +1742,8 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
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if (qtype == T_CNAME || qtype == T_ANY)
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{
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if ((crecp = cache_find_by_name(NULL, name, now, F_CNAME | (dryrun ? F_NO_RR : 0))) &&
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- (qtype == T_CNAME || (crecp->flags & F_CONFIG)) &&
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- ((crecp->flags & F_CONFIG) || !do_bit || (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK))))
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+ ((qtype == T_CNAME && rd_bit) || (crecp->flags & F_CONFIG)) &&
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+ ((crecp->flags & F_CONFIG) || (!do_bit || cache_validated(crecp))))
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{
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if (!(crecp->flags & F_DNSSECOK))
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sec_data = 0;
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@@ -1780,7 +1781,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
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}
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}
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- if (!found && (option_bool(OPT_SELFMX) || option_bool(OPT_LOCALMX)) &&
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+ if (!found && (option_bool(OPT_SELFMX) || option_bool(OPT_LOCALMX)) &&
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cache_find_by_name(NULL, name, now, F_HOSTS | F_DHCP | F_NO_RR))
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{
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ans = 1;
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--
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2.21.0
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