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Handle CNAMEs to DS records when confirming absence of DS for DNSSEC.

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This commit is contained in:
Simon Kelley
2015-06-12 21:39:11 +01:00
parent f7bfbdc872
commit e3ec6f0bd7
2 changed files with 68 additions and 10 deletions
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36
src/dnssec.c
View File

@@ -1223,9 +1223,12 @@ int dnssec_validate_ds(time_t now, struct dns_header *header, size_t plen, char
val = dnssec_validate_reply(now, header, plen, name, keyname, NULL, &neganswer, &nons);
/* Note dnssec_validate_reply() will have cached positive answers */
if (val == STAT_NO_SIG || val == STAT_INSECURE)
if (val == STAT_INSECURE)
val = STAT_BOGUS;
if (val == STAT_NO_SIG)
return val;
p = (unsigned char *)(header+1);
extract_name(header, plen, &p, name, 1, 4);
p += 4; /* qtype, qclass */
@@ -1878,7 +1881,10 @@ int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, ch
/* No data, therefore no sigs */
if (ntohs(header->ancount) + ntohs(header->nscount) == 0)
return STAT_NO_SIG;
{
*keyname = 0;
return STAT_NO_SIG;
}
for (p1 = ans_start, i = 0; i < ntohs(header->ancount) + ntohs(header->nscount); i++)
{
@@ -1948,6 +1954,19 @@ int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, ch
{
if (class)
*class = class1; /* Class for DS or DNSKEY */
if (rc == STAT_NO_SIG)
{
/* If we dropped off the end of a CNAME chain, return
STAT_NO_SIG and the last name is keyname. This is used for proving non-existence
if DS records in CNAME chains. */
if (cname_count == CNAME_CHAIN || i < ntohs(header->ancount))
/* No CNAME chain, or no sig in answer section, return empty name. */
*keyname = 0;
else if (!extract_name(header, plen, &qname, keyname, 1, 0))
return STAT_BOGUS;
}
return rc;
}
@@ -2060,8 +2079,17 @@ int dnssec_validate_reply(time_t now, struct dns_header *header, size_t plen, ch
/* NXDOMAIN or NODATA reply, prove that (name, class1, type1) can't exist */
/* First marshall the NSEC records, if we've not done it previously */
if (!nsec_type && !(nsec_type = find_nsec_records(header, plen, &nsecs, &nsec_count, qclass)))
return STAT_NO_SIG; /* No NSECs, this is probably a dangling CNAME pointing into
an unsigned zone. Return STAT_NO_SIG to cause this to be proved. */
{
/* No NSEC records. If we dropped off the end of a CNAME chain, return
STAT_NO_SIG and the last name is keyname. This is used for proving non-existence
if DS records in CNAME chains. */
if (cname_count == CNAME_CHAIN) /* No CNAME chain, return empty name. */
*keyname = 0;
else if (!extract_name(header, plen, &qname, keyname, 1, 0))
return STAT_BOGUS;
return STAT_NO_SIG; /* No NSECs, this is probably a dangling CNAME pointing into
an unsigned zone. Return STAT_NO_SIG to cause this to be proved. */
}
/* Get name of missing answer */
if (!extract_name(header, plen, &qname, name, 1, 0))

38
src/forward.c
View File

@@ -851,7 +851,7 @@ void reply_query(int fd, int family, time_t now)
Avoid caching a reply with sigs if there's a vaildated break in the
DS chain, so we don't return replies from cache missing sigs. */
status = STAT_INSECURE_DS;
else if (status == STAT_NO_NS)
else if (status == STAT_NO_NS || status == STAT_NO_SIG)
status = STAT_BOGUS;
}
else if (forward->flags & FREC_CHECK_NOSIGN)
@@ -997,7 +997,7 @@ void reply_query(int fd, int family, time_t now)
Avoid caching a reply with sigs if there's a vaildated break in the
DS chain, so we don't return replies from cache missing sigs. */
status = STAT_INSECURE_DS;
else if (status == STAT_NO_NS)
else if (status == STAT_NO_NS || status == STAT_NO_SIG)
status = STAT_BOGUS;
}
else if (forward->flags & FREC_CHECK_NOSIGN)
@@ -1456,6 +1456,21 @@ static int do_check_sign(struct frec *forward, int status, time_t now, char *nam
if (status == STAT_BOGUS)
return STAT_BOGUS;
if (status == STAT_NO_SIG && *keyname != 0)
{
/* There is a validated CNAME chain that doesn't end in a DS record. Start
the search again in that domain. */
blockdata_free(forward->orig_domain);
forward->name_start = strlen(keyname);
forward->name_len = forward->name_start + 1;
if (!(forward->orig_domain = blockdata_alloc(keyname, forward->name_len)))
return STAT_BOGUS;
strcpy(name, keyname);
status = 0; /* force to cache when we iterate. */
continue;
}
/* There's a proven DS record, or we're within a zone, where there doesn't need
to be a DS record. Add a name and try again.
If we've already tried the whole name, then fail */
@@ -1572,6 +1587,21 @@ static int tcp_check_for_unsigned_zone(time_t now, struct dns_header *header, s
return STAT_INSECURE;
}
if (status == STAT_NO_SIG && *keyname != 0)
{
/* There is a validated CNAME chain that doesn't end in a DS record. Start
the search again in that domain. */
blockdata_free(block);
name_len = strlen(keyname) + 1;
name_start = name + name_len - 1;
if (!(block = blockdata_alloc(keyname, name_len)))
return STAT_BOGUS;
strcpy(name, keyname);
continue;
}
if (status == STAT_BOGUS)
{
free(packet);
@@ -1627,7 +1657,7 @@ static int tcp_key_recurse(time_t now, int status, struct dns_header *header, si
{
if (new_status == STAT_NO_DS)
new_status = STAT_INSECURE_DS;
else if (new_status == STAT_NO_NS)
else if (new_status == STAT_NO_NS || new_status == STAT_NO_SIG)
new_status = STAT_BOGUS;
}
}
@@ -1692,7 +1722,7 @@ static int tcp_key_recurse(time_t now, int status, struct dns_header *header, si
{
if (new_status == STAT_NO_DS)
new_status = STAT_INSECURE_DS;
else if (new_status == STAT_NO_NS)
else if (new_status == STAT_NO_NS || new_status == STAT_NO_SIG)
new_status = STAT_BOGUS; /* Validated no DS */
}
}