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authorLennart Poettering <lennart@poettering.net>2015-12-21 21:06:29 +0100
committerLennart Poettering <lennart@poettering.net>2015-12-26 19:09:10 +0100
commitdb5b0e92b3c23e6f360bd0f44a655b35921a6c98 (patch)
treefd0e65c2ffbb98361882c76bbbabd6408ec91a2d
parent13b78323bad1e41e0474b833da2a0b72aab56f09 (diff)
resolved: tighten search for NSEC3 RRs a bit
Be stricter when searching suitable NSEC3 RRs for proof: generalize the check we use to find suitable NSEC3 RRs, in nsec3_is_good(), and add additional checks, such as checking whether all NSEC3 RRs use the same parameters, have the same suffix and so on.
-rw-r--r--src/resolve/resolved-dns-dnssec.c134
-rw-r--r--src/resolve/resolved-dns-transaction.c2
-rw-r--r--src/shared/dns-domain.c18
-rw-r--r--src/shared/dns-domain.h2
-rw-r--r--src/test/test-dns-domain.c32
5 files changed, 131 insertions, 57 deletions
diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c
index dbda71b03d..edd1efc739 100644
--- a/src/resolve/resolved-dns-dnssec.c
+++ b/src/resolve/resolved-dns-dnssec.c
@@ -909,11 +909,63 @@ finish:
return r;
}
+static int nsec3_is_good(DnsResourceRecord *rr, DnsAnswerFlags flags, DnsResourceRecord *nsec3) {
+ const char *a, *b;
+ int r;
+
+ assert(rr);
+
+ if ((flags & DNS_ANSWER_AUTHENTICATED) == 0)
+ return 0;
+
+ if (rr->key->type != DNS_TYPE_NSEC3)
+ return 0;
+
+ /* RFC 5155, Section 8.2 says we MUST ignore NSEC3 RRs with flags != 0 or 1 */
+ if (!IN_SET(rr->nsec3.flags, 0, 1))
+ return 0;
+
+ if (!nsec3)
+ return 1;
+
+ /* If a second NSEC3 RR is specified, also check if they are from the same zone. */
+
+ if (nsec3 == rr) /* Shortcut */
+ return 1;
+
+ if (rr->key->class != nsec3->key->class)
+ return 0;
+ if (rr->nsec3.algorithm != nsec3->nsec3.algorithm)
+ return 0;
+ if (rr->nsec3.iterations != nsec3->nsec3.iterations)
+ return 0;
+ if (rr->nsec3.salt_size != nsec3->nsec3.salt_size)
+ return 0;
+ if (memcmp(rr->nsec3.salt, nsec3->nsec3.salt, rr->nsec3.salt_size) != 0)
+ return 0;
+
+ a = DNS_RESOURCE_KEY_NAME(rr->key);
+ r = dns_name_parent(&a); /* strip off hash */
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return 0;
+
+ b = DNS_RESOURCE_KEY_NAME(nsec3->key);
+ r = dns_name_parent(&b); /* strip off hash */
+ if (r < 0)
+ return r;
+ if (r == 0)
+ return 0;
+
+ return dns_name_equal(a, b);
+}
+
static int dnssec_test_nsec3(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecResult *result) {
_cleanup_free_ char *next_closer_domain = NULL, *l = NULL;
uint8_t hashed[DNSSEC_HASH_SIZE_MAX];
const char *suffix, *p, *pp = NULL;
- DnsResourceRecord *rr;
+ DnsResourceRecord *rr, *suffix_rr;
DnsAnswerFlags flags;
int hashed_size, r;
@@ -923,20 +975,16 @@ static int dnssec_test_nsec3(DnsAnswer *answer, DnsResourceKey *key, DnssecNsecR
/* First step, look for the longest common suffix we find with any NSEC3 RR in the response. */
suffix = DNS_RESOURCE_KEY_NAME(key);
for (;;) {
- DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
+ DNS_ANSWER_FOREACH_FLAGS(suffix_rr, flags, answer) {
_cleanup_free_ char *hashed_domain = NULL, *label = NULL;
- if ((flags & DNS_ANSWER_AUTHENTICATED) == 0)
- continue;
-
- if (rr->key->type != DNS_TYPE_NSEC3)
- continue;
-
- /* RFC 5155, Section 8.2 says we MUST ignore NSEC3 RRs with flags != 0 or 1 */
- if (!IN_SET(rr->nsec3.flags, 0, 1))
+ r = nsec3_is_good(suffix_rr, flags, NULL);
+ if (r < 0)
+ return r;
+ if (r == 0)
continue;
- r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(rr->key), suffix);
+ r = dns_name_equal_skip(DNS_RESOURCE_KEY_NAME(suffix_rr->key), 1, suffix);
if (r < 0)
return r;
if (r > 0)
@@ -958,42 +1006,34 @@ found_suffix:
/* Second step, find the closest encloser NSEC3 RR in 'answer' that matches 'key' */
p = DNS_RESOURCE_KEY_NAME(key);
for (;;) {
- DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
- _cleanup_free_ char *hashed_domain = NULL, *label = NULL;
+ _cleanup_free_ char *hashed_domain = NULL, *label = NULL;
- if ((flags & DNS_ANSWER_AUTHENTICATED) == 0)
- continue;
+ hashed_size = dnssec_nsec3_hash(suffix_rr, p, hashed);
+ if (hashed_size == -EOPNOTSUPP) {
+ *result = DNSSEC_NSEC_UNSUPPORTED_ALGORITHM;
+ return 0;
+ }
+ if (hashed_size < 0)
+ return hashed_size;
- if (rr->key->type != DNS_TYPE_NSEC3)
- continue;
+ label = base32hexmem(hashed, hashed_size, false);
+ if (!label)
+ return -ENOMEM;
- /* RFC 5155, Section 8.2 says we MUST ignore NSEC3 RRs with flags != 0 or 1 */
- if (!IN_SET(rr->nsec3.flags, 0, 1))
- continue;
+ hashed_domain = strjoin(label, ".", suffix, NULL);
+ if (!hashed_domain)
+ return -ENOMEM;
+
+ DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
- r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(rr->key), suffix);
+ r = nsec3_is_good(rr, flags, suffix_rr);
if (r < 0)
return r;
if (r == 0)
continue;
- hashed_size = dnssec_nsec3_hash(rr, p, hashed);
- if (hashed_size == -EOPNOTSUPP) {
- *result = DNSSEC_NSEC_UNSUPPORTED_ALGORITHM;
- return 0;
- }
- if (hashed_size < 0)
- return hashed_size;
if (rr->nsec3.next_hashed_name_size != (size_t) hashed_size)
- return -EBADMSG;
-
- label = base32hexmem(hashed, hashed_size, false);
- if (!label)
- return -ENOMEM;
-
- hashed_domain = strjoin(label, ".", suffix, NULL);
- if (!hashed_domain)
- return -ENOMEM;
+ continue;
r = dns_name_equal(DNS_RESOURCE_KEY_NAME(rr->key), hashed_domain);
if (r < 0)
@@ -1056,26 +1096,8 @@ found_closest_encloser:
DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) {
_cleanup_free_ char *label = NULL, *next_hashed_domain = NULL;
- const char *nsec3_parent;
-
- if ((flags & DNS_ANSWER_AUTHENTICATED) == 0)
- continue;
-
- if (rr->key->type != DNS_TYPE_NSEC3)
- continue;
-
- /* RFC 5155, Section 8.2 says we MUST ignore NSEC3 RRs with flags != 0 or 1 */
- if (!IN_SET(rr->nsec3.flags, 0, 1))
- continue;
-
- nsec3_parent = DNS_RESOURCE_KEY_NAME(rr->key);
- r = dns_name_parent(&nsec3_parent);
- if (r < 0)
- return r;
- if (r == 0)
- continue;
- r = dns_name_equal(p, nsec3_parent);
+ r = nsec3_is_good(rr, flags, suffix_rr);
if (r < 0)
return r;
if (r == 0)
diff --git a/src/resolve/resolved-dns-transaction.c b/src/resolve/resolved-dns-transaction.c
index d2aec13264..1d02d7e942 100644
--- a/src/resolve/resolved-dns-transaction.c
+++ b/src/resolve/resolved-dns-transaction.c
@@ -1516,7 +1516,7 @@ int dns_transaction_request_dnssec_keys(DnsTransaction *t) {
if (!soa)
return -ENOMEM;
- log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned non-SOA/NS RRset).", t->id, DNS_RESOURCE_KEY_NAME(rr->key));
+ log_debug("Requesting SOA to validate transaction %" PRIu16 " (%s, unsigned non-SOA/NS RRset <%s>).", t->id, DNS_RESOURCE_KEY_NAME(rr->key), dns_resource_record_to_string(rr));
r = dns_transaction_request_dnssec_rr(t, soa);
if (r < 0)
return r;
diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c
index f3dbf60395..f44e80c9db 100644
--- a/src/shared/dns-domain.c
+++ b/src/shared/dns-domain.c
@@ -1215,3 +1215,21 @@ int dns_name_count_labels(const char *name) {
return (int) n;
}
+
+int dns_name_equal_skip(const char *a, unsigned n_labels, const char *b) {
+ int r;
+
+ assert(a);
+ assert(b);
+
+ while (n_labels > 0) {
+
+ r = dns_name_parent(&a);
+ if (r <= 0)
+ return r;
+
+ n_labels --;
+ }
+
+ return dns_name_equal(a, b);
+}
diff --git a/src/shared/dns-domain.h b/src/shared/dns-domain.h
index 7b509729fb..dd8ae3ac98 100644
--- a/src/shared/dns-domain.h
+++ b/src/shared/dns-domain.h
@@ -102,3 +102,5 @@ int dns_service_split(const char *joined, char **name, char **type, char **domai
int dns_name_suffix(const char *name, unsigned n_labels, const char **ret);
int dns_name_count_labels(const char *name);
+
+int dns_name_equal_skip(const char *a, unsigned n_labels, const char *b);
diff --git a/src/test/test-dns-domain.c b/src/test/test-dns-domain.c
index 3a15ea5c06..78c5631ff1 100644
--- a/src/test/test-dns-domain.c
+++ b/src/test/test-dns-domain.c
@@ -515,6 +515,37 @@ static void test_dns_name_count_labels(void) {
test_dns_name_count_labels_one("..", -EINVAL);
}
+static void test_dns_name_equal_skip_one(const char *a, unsigned n_labels, const char *b, int ret) {
+ assert_se(dns_name_equal_skip(a, n_labels, b) == ret);
+}
+
+static void test_dns_name_equal_skip(void) {
+ test_dns_name_equal_skip_one("foo", 0, "bar", 0);
+ test_dns_name_equal_skip_one("foo", 0, "foo", 1);
+ test_dns_name_equal_skip_one("foo", 1, "foo", 0);
+ test_dns_name_equal_skip_one("foo", 2, "foo", 0);
+
+ test_dns_name_equal_skip_one("foo.bar", 0, "foo.bar", 1);
+ test_dns_name_equal_skip_one("foo.bar", 1, "foo.bar", 0);
+ test_dns_name_equal_skip_one("foo.bar", 2, "foo.bar", 0);
+ test_dns_name_equal_skip_one("foo.bar", 3, "foo.bar", 0);
+
+ test_dns_name_equal_skip_one("foo.bar", 0, "bar", 0);
+ test_dns_name_equal_skip_one("foo.bar", 1, "bar", 1);
+ test_dns_name_equal_skip_one("foo.bar", 2, "bar", 0);
+ test_dns_name_equal_skip_one("foo.bar", 3, "bar", 0);
+
+ test_dns_name_equal_skip_one("foo.bar", 0, "", 0);
+ test_dns_name_equal_skip_one("foo.bar", 1, "", 0);
+ test_dns_name_equal_skip_one("foo.bar", 2, "", 1);
+ test_dns_name_equal_skip_one("foo.bar", 3, "", 0);
+
+ test_dns_name_equal_skip_one("", 0, "", 1);
+ test_dns_name_equal_skip_one("", 1, "", 0);
+ test_dns_name_equal_skip_one("", 1, "foo", 0);
+ test_dns_name_equal_skip_one("", 2, "foo", 0);
+}
+
int main(int argc, char *argv[]) {
test_dns_label_unescape();
@@ -537,6 +568,7 @@ int main(int argc, char *argv[]) {
test_dns_name_change_suffix();
test_dns_name_suffix();
test_dns_name_count_labels();
+ test_dns_name_equal_skip();
return 0;
}