|
 |
e20e41 |
From 5fe8a0fc4d817fa6be42cd28c40752e38ee678b1 Mon Sep 17 00:00:00 2001
|
|
|
e20e41 |
From: Simon Kelley <simon@thekelleys.org.uk>
|
|
|
e20e41 |
Date: Fri, 29 Jun 2018 14:39:41 +0100
|
|
|
e20e41 |
Subject: [PATCH 2/2] Fix sometimes missing DNSSEC RRs when DNSSEC validation
|
|
|
e20e41 |
not enabled.
|
|
|
e20e41 |
|
|
|
e20e41 |
Dnsmasq does pass on the do-bit, and return DNSSEC RRs, irrespective
|
|
|
e20e41 |
of of having DNSSEC validation compiled in or enabled.
|
|
|
e20e41 |
|
|
|
e20e41 |
The thing to understand here is that the cache does not store all the
|
|
|
e20e41 |
DNSSEC RRs, and dnsmasq doesn't have the (very complex) logic required
|
|
|
e20e41 |
to determine the set of DNSSEC RRs required in an answer. Therefore if
|
|
|
e20e41 |
the client wants the DNSSEC RRs, the query can not be answered from
|
|
|
e20e41 |
the cache. When DNSSEC validation is enabled, any query with the
|
|
|
e20e41 |
do-bit set is never answered from the cache, unless the domain is
|
|
|
e20e41 |
known not to be signed: the query is always forwarded. This ensures
|
|
|
e20e41 |
that the DNSEC RRs are included.
|
|
|
e20e41 |
|
|
|
e20e41 |
The same thing should be true when DNSSEC validation is not enabled,
|
|
|
e20e41 |
but there's a bug in the logic.
|
|
|
e20e41 |
|
|
|
e20e41 |
line 1666 of src/rfc1035.c looks like this
|
|
|
e20e41 |
|
|
|
e20e41 |
if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) || !do_bit || !(crecp->flags & F_DNSSECOK))
|
|
|
e20e41 |
|
|
|
e20e41 |
{ ...answer from cache ... }
|
|
|
e20e41 |
|
|
|
e20e41 |
So local stuff (hosts, DHCP, ) get answered. If the do_bit is not set
|
|
|
e20e41 |
then the query is answered, and if the domain is known not to be
|
|
|
e20e41 |
signed, the query is answered.
|
|
|
e20e41 |
|
|
|
e20e41 |
Unfortunately, if DNSSEC validation is not turned on then the
|
|
|
e20e41 |
F_DNSSECOK bit is not valid, and it's always zero, so the question
|
|
|
e20e41 |
always gets answered from the cache, even when the do-bit is set.
|
|
|
e20e41 |
|
|
|
e20e41 |
This code should look like that at line 1468, dealing with PTR queries
|
|
|
e20e41 |
|
|
|
e20e41 |
if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
|
|
|
e20e41 |
!do_bit ||
|
|
|
e20e41 |
(option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK)))
|
|
|
e20e41 |
|
|
|
e20e41 |
where the F_DNSSECOK bit is only used when validation is enabled.
|
|
|
e20e41 |
|
|
|
e20e41 |
(cherry picked from commit a997ca0da044719a0ce8a232d14da8b30022592b)
|
|
|
e20e41 |
---
|
|
|
e20e41 |
src/rfc1035.c | 6 ++++--
|
|
|
e20e41 |
1 file changed, 4 insertions(+), 2 deletions(-)
|
|
|
e20e41 |
|
|
|
e20e41 |
diff --git a/src/rfc1035.c b/src/rfc1035.c
|
|
|
e20e41 |
index 607412f..96acae9 100644
|
|
|
e20e41 |
--- a/src/rfc1035.c
|
|
|
e20e41 |
+++ b/src/rfc1035.c
|
|
|
e20e41 |
@@ -1632,7 +1632,9 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
|
|
|
e20e41 |
}
|
|
|
e20e41 |
|
|
|
e20e41 |
/* If the client asked for DNSSEC don't use cached data. */
|
|
|
e20e41 |
- if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) || !do_bit || !(crecp->flags & F_DNSSECOK))
|
|
|
e20e41 |
+ if ((crecp->flags & (F_HOSTS | F_DHCP | F_CONFIG)) ||
|
|
|
e20e41 |
+ !do_bit ||
|
|
|
e20e41 |
+ (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK)))
|
|
|
e20e41 |
do
|
|
|
e20e41 |
{
|
|
|
e20e41 |
/* don't answer wildcard queries with data not from /etc/hosts
|
|
|
e20e41 |
@@ -1716,7 +1718,7 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
|
|
|
e20e41 |
{
|
|
|
e20e41 |
if ((crecp = cache_find_by_name(NULL, name, now, F_CNAME | (dryrun ? F_NO_RR : 0))) &&
|
|
|
e20e41 |
(qtype == T_CNAME || (crecp->flags & F_CONFIG)) &&
|
|
|
e20e41 |
- ((crecp->flags & F_CONFIG) || !do_bit || !(crecp->flags & F_DNSSECOK)))
|
|
|
e20e41 |
+ ((crecp->flags & F_CONFIG) || !do_bit || (option_bool(OPT_DNSSEC_VALID) && !(crecp->flags & F_DNSSECOK))))
|
|
|
e20e41 |
{
|
|
|
e20e41 |
if (!(crecp->flags & F_DNSSECOK))
|
|
|
e20e41 |
sec_data = 0;
|
|
|
e20e41 |
--
|
|
|
e20e41 |
2.20.1
|
|
|
e20e41 |
|