Fixed bug #9356 Incomplete validation of IP Address fields in subjectAltNames

IPv6 addresses are valid entries in subjectAltNames. Certificate Authorities may issue certificates including IPv6 addresses except if they fall within addresses in the RFC 4193 range. Google and CloudFlare provide IPv6 addresses in their DNS over HTTPS services.

Internal CAs do not have those restrictions and can issue Unique local addresses in certificates.

Author: lucasnetau

ext/openssl/tests/san_ipv6_peer_matching.phpt

@@ -0,0 +1,64 @@
+--TEST--
+IPv6 Peer verification matches SAN names
+--EXTENSIONS--
+openssl
+--SKIPIF--
+<?php
+if (!function_exists("proc_open")) die("skip no proc_open");
+?>
+--FILE--
+<?php
+$certFile = __DIR__ . DIRECTORY_SEPARATOR . 'san_ipv6_peer_matching.pem.tmp';
+$san = 'IP:2001:db8:85a3:8d3:1319:8a2e:370:7348';
+
+$serverCode = <<<'CODE'
+    $serverUri = "ssl://[::1]:64321";
+    $serverFlags = STREAM_SERVER_BIND | STREAM_SERVER_LISTEN;
+    $serverCtx = stream_context_create(['ssl' => [
+        'local_cert' => '%s',
+    ]]);
+
+    $server = stream_socket_server($serverUri, $errno, $errstr, $serverFlags, $serverCtx);
+    phpt_notify();
+
+    @stream_socket_accept($server, 1);
+    @stream_socket_accept($server, 1);
+CODE;
+$serverCode = sprintf($serverCode, $certFile);
+
+$clientCode = <<<'CODE'
+    $serverUri = "ssl://[::1]:64321";
+    $clientFlags = STREAM_CLIENT_CONNECT;
+    $clientCtx = stream_context_create(['ssl' => [
+        'verify_peer' => false,
+    ]]);
+
+    phpt_wait();
+
+    stream_context_set_option($clientCtx, 'ssl', 'peer_name', '2001:db8:85a3:8d3:1319:8a2e:370:7348');
+    var_dump(stream_socket_client($serverUri, $errno, $errstr, 1, $clientFlags, $clientCtx));
+
+    stream_context_set_option($clientCtx, 'ssl', 'peer_name', '2001:db8:85a3:8d3:1319:8a2e:370:7349');
+    var_dump(stream_socket_client($serverUri, $errno, $errstr, 1, $clientFlags, $clientCtx));
+CODE;
+
+include 'CertificateGenerator.inc';
+$certificateGenerator = new CertificateGenerator();
+$certificateGenerator->saveNewCertAsFileWithKey(null, $certFile, null, $san);
+
+include 'ServerClientTestCase.inc';
+ServerClientTestCase::getInstance()->run($clientCode, $serverCode);
+?>
+--CLEAN--
+<?php
+@unlink(__DIR__ . DIRECTORY_SEPARATOR . 'san_ipv6_peer_matching.pem.tmp');
+?>
+--EXPECTF--
+resource(%d) of type (stream)
+
+Warning: stream_socket_client(): Unable to locate peer certificate CN in %s on line %d
+
+Warning: stream_socket_client(): Failed to enable crypto in %s on line %d
+
+Warning: stream_socket_client(): Unable to connect to ssl://[::1]:64321 (Unknown error) in %s on line %d
+bool(false)

ext/openssl/xp_ssl.c

@@ -44,6 +44,8 @@
 #undef X509_NAME
 #undef X509_CERT_PAIR
 #undef X509_EXTENSIONS
+#else
+#include <arpa/inet.h>
 #endif
 
 /* Flags for determining allowed stream crypto methods */
@@ -110,6 +112,21 @@
 #define PHP_X509_NAME_ENTRY_TO_UTF8(ne, i, out) \
 	ASN1_STRING_to_UTF8(&out, X509_NAME_ENTRY_get_data(X509_NAME_get_entry(ne, i)))
 
+/* Used for IPv6 Address peer verification */
+#define EXPAND_IPV6_ADDRESS(_str, _bytes) \
+	do { \
+		snprintf(_str, 39, "%X:%X:%X:%X:%X:%X:%X:%X", \
+			_bytes[0] << 8 | _bytes[1], \
+			_bytes[2] << 8 | _bytes[3], \
+			_bytes[4] << 8 | _bytes[5], \
+			_bytes[6] << 8 | _bytes[7], \
+			_bytes[8] << 8 | _bytes[9], \
+			_bytes[10] << 8 | _bytes[11], \
+			_bytes[12] << 8 | _bytes[13], \
+			_bytes[14] << 8 | _bytes[15] \
+		); \
+	} while(0)
+
 #if PHP_OPENSSL_API_VERSION < 0x10100
 static RSA *php_openssl_tmp_rsa_cb(SSL *s, int is_export, int keylength);
 #endif
@@ -416,11 +433,18 @@ static bool php_openssl_matches_san_list(X509 *peer, const char *subject_name) /
 {
 	int i, len;
 	unsigned char *cert_name = NULL;
-	char ipbuffer[64];
+	char ipbuffer[64], ipv6_expanded[40];
+    unsigned char ipv6[16];
 
 	GENERAL_NAMES *alt_names = X509_get_ext_d2i(peer, NID_subject_alt_name, 0, 0);
 	int alt_name_count = sk_GENERAL_NAME_num(alt_names);
 
+	/* detect if subject name is an IPv6 address and expand once if required */
+	ipv6_expanded[0] = 0;
+	if (inet_pton(AF_INET6,subject_name,&ipv6)) {
+    	EXPAND_IPV6_ADDRESS(ipv6_expanded, ipv6);
+    }
+
 	for (i = 0; i < alt_name_count; i++) {
 		GENERAL_NAME *san = sk_GENERAL_NAME_value(alt_names, i);
 
@@ -456,13 +480,17 @@ static bool php_openssl_matches_san_list(X509 *peer, const char *subject_name) /
 				if (strcasecmp(subject_name, (const char*)ipbuffer) == 0) {
 					sk_GENERAL_NAME_pop_free(alt_names, GENERAL_NAME_free);
 
+					return 1;
+				}
+			} else if (san->d.ip->length == 16 && strlen(ipv6_expanded) >= 15) { /* shortest expanded IPv6 address is 0:0:0:0:0:0:0:0 */
+				ipbuffer[0] = 0;
+				EXPAND_IPV6_ADDRESS(ipbuffer, san->d.iPAddress->data);
+				if (strcasecmp((const char*)ipv6_expanded, (const char*)ipbuffer) == 0) {
+					sk_GENERAL_NAME_pop_free(alt_names, GENERAL_NAME_free);
+
 					return 1;
 				}
 			}
-			/* No, we aren't bothering to check IPv6 addresses. Why?
-			 * Because IP SAN names are officially deprecated and are
-			 * not allowed by CAs starting in 2015. Deal with it.
-			 */
 		}
 	}