ComputerSurge/bind9
3
0
Fork 0
Code Pull Requests 1 Activity

Fix rpz wildcard name matching

Browse Source 
Whenever an exact match is found by dns_rbt_findnode(),
the highest level node in the chain will not be put into
chain->levels[] array, but instead the chain->end
pointer will be adjusted to point to that node.

Suppose we have the following entries in a rpz zone:
example.com     CNAME rpz-passthru.
*.example.com   CNAME rpz-passthru.

A query for www.example.com would result in the
following chain object returned by dns_rbt_findnode():

chain->level_count = 2
chain->level_matches = 2
chain->levels[0] = .
chain->levels[1] = example.com
chain->levels[2] = NULL
chain->end = www

Since exact matches only care for testing rpz set bits,
we need to test for rpz wild bits through iterating the nodechain, and
that includes testing the rpz wild bits in the highest level node found.

In the case of an exact match, chain->levels[chain->level_matches]
will be NULL, to address that we must use chain->end as the start point,
then iterate over the remaining levels in the chain.
This commit is contained in:
Diego Fronza
2020-07-21 17:59:04 -03:00
committed by Evan Hunt
parent 51babc2cd3
commit 33ae88f08d
1 changed files with 41 additions and 2 deletions
Download Patch File Download Diff File Expand all files Collapse all files

43
lib/dns/rpz.c
View File

@@ -2326,7 +2326,40 @@ dns_rpz_find_name(dns_rpz_zones_t *rpzs, dns_rpz_type_t rpz_type,
case DNS_R_PARTIALMATCH:
i = chain.level_matches;
while (i >= 0 && (nmnode = chain.levels[i]) != NULL) {
nmnode = chain.levels[chain.level_matches];
/* Whenever an exact match is found by dns_rbt_findnode(),
* the highest level node in the chain will not be put into
* chain->levels[] array, but instead the chain->end
* pointer will be adjusted to point to that node.
*
* Suppose we have the following entries in a rpz zone:
* example.com CNAME rpz-passthru.
* *.example.com CNAME rpz-passthru.
*
* A query for www.example.com would result in the
* following chain object returned by dns_rbt_findnode():
* chain->level_count = 2
* chain->level_matches = 2
* chain->levels[0] = .
* chain->levels[1] = example.com
* chain->levels[2] = NULL
* chain->end = www
*
* Since exact matches only care for testing rpz set bits,
* we need to test for rpz wild bits through iterating the
* nodechain, and that includes testing the rpz wild bits in the
* highest level node found. In the case of an exact match,
* chain->levels[chain->level_matches] will be NULL, to address
* that we must use chain->end as the start
* point, then iterate over the remaining levels in the chain.
*/
if (nmnode == NULL) {
--i;
nmnode = chain.end;
}
while (nmnode != NULL) {
nm_data = nmnode->data;
if (nm_data != NULL) {
if (rpz_type == DNS_RPZ_TYPE_QNAME) {
@@ -2335,7 +2368,13 @@ dns_rpz_find_name(dns_rpz_zones_t *rpzs, dns_rpz_type_t rpz_type,
found_zbits |= nm_data->wild.ns;
}
}
i--;
if (i >= 0) {
nmnode = chain.levels[i];
--i;
} else {
break;
}
}
break;