_gnutls_pkcs11_verify_crt_status: check validity against system cert

To verify a certificate chain, this function replaces known
certificates with the ones in the system trust store if possible.

However, if it is found, the function checks the validity of the
original certificate rather than the certificate found in the trust
store.  That reveals a problem in a scenario that (1) a certificate is
signed by multiple issuers and (2) one of the issuers' certificate has
expired and included in the input chain.

This patch makes it a little robuster by actually retrieving the
certificate from the trust store and perform check against it.

Signed-off-by: Daiki Ueno <ueno@gnu.org>

3 files changed, 80 insertions, 30 deletions

diff --git a/lib/pkcs11.c b/lib/pkcs11.c
index fad16aaf4f..d8d4a65114 100644
--- a/lib/pkcs11.c
+++ b/lib/pkcs11.c
@@ -4547,34 +4547,10 @@ int gnutls_pkcs11_get_raw_issuer_by_subject_key_id (const char *url,
 	return ret;
 }
 
-/**
- * gnutls_pkcs11_crt_is_known:
- * @url: A PKCS 11 url identifying a token
- * @cert: is the certificate to find issuer for
- * @issuer: Will hold the issuer if any in an allocated buffer.
- * @fmt: The format of the exported issuer.
- * @flags: Use zero or flags from %GNUTLS_PKCS11_OBJ_FLAG.
- *
- * This function will check whether the provided certificate is stored
- * in the specified token. This is useful in combination with 
- * %GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_TRUSTED or
- * %GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_DISTRUSTED,
- * to check whether a CA is present or a certificate is blacklisted in
- * a trust PKCS #11 module.
- *
- * This function can be used with a @url of "pkcs11:", and in that case all modules
- * will be searched. To restrict the modules to the marked as trusted in p11-kit
- * use the %GNUTLS_PKCS11_OBJ_FLAG_PRESENT_IN_TRUSTED_MODULE flag.
- *
- * Note that the flag %GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_DISTRUSTED is
- * specific to p11-kit trust modules.
- *
- * Returns: If the certificate exists non-zero is returned, otherwise zero.
- *
- * Since: 3.3.0
- **/
-unsigned gnutls_pkcs11_crt_is_known(const char *url, gnutls_x509_crt_t cert,
-				 unsigned int flags)
+unsigned
+_gnutls_pkcs11_crt_is_known(const char *url, gnutls_x509_crt_t cert,
+			    unsigned int flags,
+			    gnutls_x509_crt_t *trusted_cert)
 {
 	int ret;
 	struct find_cert_st priv;
@@ -4586,6 +4562,15 @@ unsigned gnutls_pkcs11_crt_is_known(const char *url, gnutls_x509_crt_t cert,
 
 	memset(&priv, 0, sizeof(priv));
 
+	if (trusted_cert) {
+		ret = gnutls_pkcs11_obj_init(&priv.obj);
+		if (ret < 0) {
+			gnutls_assert();
+			goto cleanup;
+		}
+		priv.need_import = 1;
+	}
+
 	if (url == NULL || url[0] == 0) {
 		url = "pkcs11:";
 	}
@@ -4632,8 +4617,18 @@ unsigned gnutls_pkcs11_crt_is_known(const char *url, gnutls_x509_crt_t cert,
 		_gnutls_debug_log("crt_is_known: did not find cert, using issuer DN + serial, using DN only\n");
 		/* attempt searching with the subject DN only */
 		gnutls_assert();
+		if (priv.obj)
+			gnutls_pkcs11_obj_deinit(priv.obj);
 		gnutls_free(priv.serial.data);
 		memset(&priv, 0, sizeof(priv));
+		if (trusted_cert) {
+			ret = gnutls_pkcs11_obj_init(&priv.obj);
+			if (ret < 0) {
+				gnutls_assert();
+				goto cleanup;
+			}
+			priv.need_import = 1;
+		}
 		priv.crt = cert;
 		priv.flags = flags;
 
@@ -4650,9 +4645,26 @@ unsigned gnutls_pkcs11_crt_is_known(const char *url, gnutls_x509_crt_t cert,
 		goto cleanup;
 	}
 
+	if (trusted_cert) {
+		ret = gnutls_x509_crt_init(trusted_cert);
+		if (ret < 0) {
+			gnutls_assert();
+			ret = 0;
+			goto cleanup;
+		}
+		ret = gnutls_x509_crt_import_pkcs11(*trusted_cert, priv.obj);
+		if (ret < 0) {
+			gnutls_assert();
+			gnutls_x509_crt_deinit(*trusted_cert);
+			ret = 0;
+			goto cleanup;
+		}
+	}
 	ret = 1;
 
       cleanup:
+	if (priv.obj)
+		gnutls_pkcs11_obj_deinit(priv.obj);
 	if (info)
 		p11_kit_uri_free(info);
 	gnutls_free(priv.serial.data);
@@ -4661,6 +4673,36 @@ unsigned gnutls_pkcs11_crt_is_known(const char *url, gnutls_x509_crt_t cert,
 }
 
 /**
+ * gnutls_pkcs11_crt_is_known:
+ * @url: A PKCS 11 url identifying a token
+ * @cert: is the certificate to find issuer for
+ * @flags: Use zero or flags from %GNUTLS_PKCS11_OBJ_FLAG.
+ *
+ * This function will check whether the provided certificate is stored
+ * in the specified token. This is useful in combination with 
+ * %GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_TRUSTED or
+ * %GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_DISTRUSTED,
+ * to check whether a CA is present or a certificate is blacklisted in
+ * a trust PKCS #11 module.
+ *
+ * This function can be used with a @url of "pkcs11:", and in that case all modules
+ * will be searched. To restrict the modules to the marked as trusted in p11-kit
+ * use the %GNUTLS_PKCS11_OBJ_FLAG_PRESENT_IN_TRUSTED_MODULE flag.
+ *
+ * Note that the flag %GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_DISTRUSTED is
+ * specific to p11-kit trust modules.
+ *
+ * Returns: If the certificate exists non-zero is returned, otherwise zero.
+ *
+ * Since: 3.3.0
+ **/
+unsigned gnutls_pkcs11_crt_is_known(const char *url, gnutls_x509_crt_t cert,
+				 unsigned int flags)
+{
+	return _gnutls_pkcs11_crt_is_known(url, cert, flags, NULL);
+}
+
+/**
  * gnutls_pkcs11_obj_get_flags:
  * @obj: The pkcs11 object
  * @oflags: Will hold the output flags
diff --git a/lib/pkcs11_int.h b/lib/pkcs11_int.h
index 9d88807098..86cce0dee5 100644
--- a/lib/pkcs11_int.h
+++ b/lib/pkcs11_int.h
@@ -460,6 +460,11 @@ inline static bool is_pkcs11_url_object(const char *url)
 	return 0;
 }
 
+unsigned
+_gnutls_pkcs11_crt_is_known(const char *url, gnutls_x509_crt_t cert,
+			    unsigned int flags,
+			    gnutls_x509_crt_t *trusted_cert);
+
 #endif				/* ENABLE_PKCS11 */
 
 #endif /* GNUTLS_LIB_PKCS11_INT_H */
diff --git a/lib/x509/verify.c b/lib/x509/verify.c
index d202670198..fd7c6a1642 100644
--- a/lib/x509/verify.c
+++ b/lib/x509/verify.c
@@ -34,6 +34,7 @@
 #include <tls-sig.h>
 #include <str.h>
 #include <datum.h>
+#include <pkcs11_int.h>
 #include <x509_int.h>
 #include <common.h>
 #include <pk.h>
@@ -1188,6 +1189,7 @@ _gnutls_pkcs11_verify_crt_status(const char* url,
 
 	for (; i < clist_size; i++) {
 		unsigned vflags;
+		gnutls_x509_crt_t trusted_cert;
 
 		if (i == 0) /* in the end certificate do full comparison */
 			vflags = GNUTLS_PKCS11_OBJ_FLAG_PRESENT_IN_TRUSTED_MODULE|
@@ -1196,9 +1198,10 @@ _gnutls_pkcs11_verify_crt_status(const char* url,
 			vflags = GNUTLS_PKCS11_OBJ_FLAG_PRESENT_IN_TRUSTED_MODULE|
 				GNUTLS_PKCS11_OBJ_FLAG_COMPARE_KEY|GNUTLS_PKCS11_OBJ_FLAG_RETRIEVE_TRUSTED;
 
-		if (gnutls_pkcs11_crt_is_known (url, certificate_list[i], vflags) != 0) {
+		if (_gnutls_pkcs11_crt_is_known (url, certificate_list[i], vflags, &trusted_cert) != 0) {
 
-			status |= check_ca_sanity(certificate_list[i], now, flags);
+			status |= check_ca_sanity(trusted_cert, now, flags);
+			gnutls_x509_crt_deinit(trusted_cert);
 
 			if (func)
 				func(certificate_list[i],