ocsp: enhanced the OCSP response loading APIs

Introduced gnutls_certificate_set_ocsp_status_request_file2() and
gnutls_certificate_set_ocsp_status_request_mem(). These functions
behave as the equivalent certificate loading functions and pre-load
the OCSP response provided as a file, either in DER or in PEM form.

In addition, ensure that if the server is provided a problematic OCSP
response, or the OCSP response is not renewed before it is invalid, we
will not provide it to the clients.

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

3 files changed, 83 insertions, 1 deletions

diff --git a/lib/x509/Makefile.am b/lib/x509/Makefile.am
index 128306b95c..a10cd2f00c 100644
--- a/lib/x509/Makefile.am
+++ b/lib/x509/Makefile.am
@@ -79,7 +79,7 @@ libgnutls_x509_la_SOURCES =	\
 	tls_features.c		\
 	krb5.c krb5.h		\
 	ip.c ip.h ip-in-cidr.h  \
-	supported_exts.h
+	supported_exts.h ocsp.h
 
 if ENABLE_OCSP
 libgnutls_x509_la_SOURCES += ocsp.c ocsp_output.c
diff --git a/lib/x509/ocsp.c b/lib/x509/ocsp.c
index 9edaa48022..0c57f7cf2e 100644
--- a/lib/x509/ocsp.c
+++ b/lib/x509/ocsp.c
@@ -32,6 +32,7 @@
 #include "common.h"
 #include "verify-high.h"
 #include "x509.h"
+#include "ocsp.h"
 
 #include <gnutls/ocsp.h>
 #include <auth/cert.h>
@@ -2543,3 +2544,54 @@ gnutls_ocsp_resp_list_import2(gnutls_ocsp_resp_t **ocsps,
 		gnutls_ocsp_resp_deinit(resp);
 	return ret;
 }
+
+/* This returns -1 if the OCSP response is invalid (revoked) or its
+ * data are too old. Otherwise it returns the time after which that data
+ * is invalid.
+ */
+time_t _gnutls_ocsp_get_validity(gnutls_ocsp_resp_t resp)
+{
+	unsigned int cert_status;
+	time_t rtime, vtime, ntime, now;
+	int ret;
+
+	ret = gnutls_ocsp_resp_get_single(resp, 0, NULL, NULL, NULL, NULL,
+					  &cert_status, &vtime, &ntime,
+					  &rtime, NULL);
+	if (ret < 0) {
+		_gnutls_debug_log("There was an error parsing the OCSP response: %s\n",
+				  gnutls_strerror(ret));
+		return gnutls_assert_val(-1);
+	}
+
+	if (cert_status != GNUTLS_OCSP_CERT_GOOD &&
+	    cert_status != GNUTLS_OCSP_CERT_UNKNOWN) {
+		_gnutls_debug_log("The OCSP response status (%d) is invalid\n",
+				  cert_status);
+		return gnutls_assert_val(-1);
+	}
+
+	now = gnutls_time(0);
+
+	if (ntime == -1) {
+		/* This is a problematic case, and there is no concensus on how
+		 * to treat these responses. It doesn't contain the time after which
+		 * the response is invalid, thus it is an OCSP response effectively
+		 * valid forever defeating the purpose of OCSP. We set here the same
+		 * limit we apply when verifying responses. */
+		if (now - vtime > MAX_OCSP_VALIDITY_SECS) {
+			_gnutls_debug_log("The OCSP response is old\n");
+			return gnutls_assert_val(-1);
+		}
+
+		return now + MAX_OCSP_VALIDITY_SECS;
+	} else {
+		/* there is a newer OCSP answer, don't trust this one */
+		if (ntime < now) {
+			_gnutls_debug_log("There is a newer OCSP response\n");
+			return gnutls_assert_val(-1);
+		}
+
+		return ntime;
+	}
+}
diff --git a/lib/x509/ocsp.h b/lib/x509/ocsp.h
new file mode 100644
index 0000000000..3d6418b184
--- /dev/null
+++ b/lib/x509/ocsp.h
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * Author: Nikos Mavrogiannopoulos
+ *
+ * This file is part of GnuTLS.
+ *
+ * The GnuTLS is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ *
+ */
+
+/* Online Certificate Status Protocol - RFC 2560
+ */
+#include <gnutls/ocsp.h>
+
+/* fifteen days */
+#define MAX_OCSP_VALIDITY_SECS (15*60*60*24)
+
+time_t _gnutls_ocsp_get_validity(gnutls_ocsp_resp_t resp);