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authorLennart Poettering <lennart@poettering.net>2015-12-21 19:57:34 +0100
committerLennart Poettering <lennart@poettering.net>2015-12-26 19:09:10 +0100
commite7ff0e0b391341bdc4d9c08dff1c477e1df6a682 (patch)
tree03852136cb91d95a6549b74a983f295abdc8c250 /src
parentd38d5ca65b3f8fd19348a7919cf1f1f07c955393 (diff)
resolved: properly implement RRSIG validation of wildcarded RRsets
Note that this is still not complete, one additional step is still missing: when we verified that a wildcard RRset is properly signed, we still need to do an NSEC/NSEC3 proof that no more specific RRset exists.
Diffstat (limited to 'src')
-rw-r--r--src/resolve/resolved-dns-dnssec.c23
-rw-r--r--src/shared/dns-domain.c56
-rw-r--r--src/shared/dns-domain.h6
-rw-r--r--src/test/test-dns-domain.c42
4 files changed, 126 insertions, 1 deletions
diff --git a/src/resolve/resolved-dns-dnssec.c b/src/resolve/resolved-dns-dnssec.c
index 814cb1c0f9..9ddad38fa6 100644
--- a/src/resolve/resolved-dns-dnssec.c
+++ b/src/resolve/resolved-dns-dnssec.c
@@ -384,10 +384,17 @@ int dnssec_verify_rrset(
gcry_md_write(md, wire_format_name, r);
for (k = 0; k < n; k++) {
+ const char *suffix;
size_t l;
rr = list[k];
- r = dns_name_to_wire_format(DNS_RESOURCE_KEY_NAME(rr->key), wire_format_name, sizeof(wire_format_name), true);
+ r = dns_name_suffix(DNS_RESOURCE_KEY_NAME(rr->key), rrsig->rrsig.labels, &suffix);
+ if (r < 0)
+ goto finish;
+ if (r > 0) /* This is a wildcard! */
+ gcry_md_write(md, (uint8_t[]) { 1, '*'}, 2);
+
+ r = dns_name_to_wire_format(suffix, wire_format_name, sizeof(wire_format_name), true);
if (r < 0)
goto finish;
gcry_md_write(md, wire_format_name, r);
@@ -497,6 +504,8 @@ int dnssec_rrsig_match_dnskey(DnsResourceRecord *rrsig, DnsResourceRecord *dnske
}
int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig) {
+ int r;
+
assert(key);
assert(rrsig);
@@ -509,6 +518,18 @@ int dnssec_key_match_rrsig(const DnsResourceKey *key, DnsResourceRecord *rrsig)
if (rrsig->rrsig.type_covered != key->type)
return 0;
+ /* Make sure signer is a parent of the RRset */
+ r = dns_name_endswith(DNS_RESOURCE_KEY_NAME(rrsig->key), rrsig->rrsig.signer);
+ if (r <= 0)
+ return r;
+
+ /* Make sure the owner name has at least as many labels as the "label" fields indicates. */
+ r = dns_name_count_labels(DNS_RESOURCE_KEY_NAME(rrsig->key));
+ if (r < 0)
+ return r;
+ if (r < rrsig->rrsig.labels)
+ return 0;
+
return dns_name_equal(DNS_RESOURCE_KEY_NAME(rrsig->key), DNS_RESOURCE_KEY_NAME(key));
}
diff --git a/src/shared/dns-domain.c b/src/shared/dns-domain.c
index c46f7d21b7..f3dbf60395 100644
--- a/src/shared/dns-domain.c
+++ b/src/shared/dns-domain.c
@@ -1159,3 +1159,59 @@ finish:
return 0;
}
+
+int dns_name_suffix(const char *name, unsigned n_labels, const char **ret) {
+ const char* labels[DNS_N_LABELS_MAX+1];
+ unsigned n = 0;
+ const char *p;
+ int r;
+
+ assert(name);
+ assert(ret);
+
+ p = name;
+ for (;;) {
+ if (n > DNS_N_LABELS_MAX)
+ return -EINVAL;
+
+ labels[n] = p;
+
+ r = dns_name_parent(&p);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ break;
+
+ n++;
+ }
+
+ if (n < n_labels)
+ return -EINVAL;
+
+ *ret = labels[n - n_labels];
+ return (int) (n - n_labels);
+}
+
+int dns_name_count_labels(const char *name) {
+ unsigned n = 0;
+ const char *p;
+ int r;
+
+ assert(name);
+
+ p = name;
+ for (;;) {
+ r = dns_name_parent(&p);
+ if (r < 0)
+ return r;
+ if (r == 0)
+ break;
+
+ if (n >= DNS_N_LABELS_MAX)
+ return -EINVAL;
+
+ n++;
+ }
+
+ return (int) n;
+}
diff --git a/src/shared/dns-domain.h b/src/shared/dns-domain.h
index 02b51832b6..7b509729fb 100644
--- a/src/shared/dns-domain.h
+++ b/src/shared/dns-domain.h
@@ -42,6 +42,9 @@
/* Maximum length of a full hostname, on the wire, including the final NUL byte */
#define DNS_WIRE_FOMAT_HOSTNAME_MAX 255
+/* Maximum number of labels per valid hostname */
+#define DNS_N_LABELS_MAX 127
+
int dns_label_unescape(const char **name, char *dest, size_t sz);
int dns_label_unescape_suffix(const char *name, const char **label_end, char *dest, size_t sz);
int dns_label_escape(const char *p, size_t l, char *dest, size_t sz);
@@ -96,3 +99,6 @@ bool dns_service_name_is_valid(const char *name);
int dns_service_join(const char *name, const char *type, const char *domain, char **ret);
int dns_service_split(const char *joined, char **name, char **type, char **domain);
+
+int dns_name_suffix(const char *name, unsigned n_labels, const char **ret);
+int dns_name_count_labels(const char *name);
diff --git a/src/test/test-dns-domain.c b/src/test/test-dns-domain.c
index de003e251c..3a15ea5c06 100644
--- a/src/test/test-dns-domain.c
+++ b/src/test/test-dns-domain.c
@@ -475,6 +475,46 @@ static void test_dns_name_change_suffix(void) {
test_dns_name_change_suffix_one("a", "b", "c", 0, NULL);
}
+static void test_dns_name_suffix_one(const char *name, unsigned n_labels, const char *result, int ret) {
+ const char *p = NULL;
+
+ assert_se(ret == dns_name_suffix(name, n_labels, &p));
+ assert_se(streq_ptr(p, result));
+}
+
+static void test_dns_name_suffix(void) {
+ test_dns_name_suffix_one("foo.bar", 2, "foo.bar", 0);
+ test_dns_name_suffix_one("foo.bar", 1, "bar", 1);
+ test_dns_name_suffix_one("foo.bar", 0, "", 2);
+ test_dns_name_suffix_one("foo.bar", 3, NULL, -EINVAL);
+ test_dns_name_suffix_one("foo.bar", 4, NULL, -EINVAL);
+
+ test_dns_name_suffix_one("bar", 1, "bar", 0);
+ test_dns_name_suffix_one("bar", 0, "", 1);
+ test_dns_name_suffix_one("bar", 2, NULL, -EINVAL);
+ test_dns_name_suffix_one("bar", 3, NULL, -EINVAL);
+
+ test_dns_name_suffix_one("", 0, "", 0);
+ test_dns_name_suffix_one("", 1, NULL, -EINVAL);
+ test_dns_name_suffix_one("", 2, NULL, -EINVAL);
+}
+
+static void test_dns_name_count_labels_one(const char *name, int n) {
+ assert_se(dns_name_count_labels(name) == n);
+}
+
+static void test_dns_name_count_labels(void) {
+ test_dns_name_count_labels_one("foo.bar.quux.", 3);
+ test_dns_name_count_labels_one("foo.bar.quux", 3);
+ test_dns_name_count_labels_one("foo.bar.", 2);
+ test_dns_name_count_labels_one("foo.bar", 2);
+ test_dns_name_count_labels_one("foo.", 1);
+ test_dns_name_count_labels_one("foo", 1);
+ test_dns_name_count_labels_one("", 0);
+ test_dns_name_count_labels_one(".", 0);
+ test_dns_name_count_labels_one("..", -EINVAL);
+}
+
int main(int argc, char *argv[]) {
test_dns_label_unescape();
@@ -495,6 +535,8 @@ int main(int argc, char *argv[]) {
test_dns_service_join();
test_dns_service_split();
test_dns_name_change_suffix();
+ test_dns_name_suffix();
+ test_dns_name_count_labels();
return 0;
}