Backported new verification functions for clients from 3.5.x branchbackport-new-verification-functions

The major use-case for the TLS protocol is verification of PKIX
certificates. However, certificate verification support while is
similar for almost all projects it requires around 100 lines of code
(a callback) to be duplicated to all applications. That patch
set gets rid of the callback and simplifies certificate verification
support, by introducing a very simple API; one that would accept
the session and the hostname only.

Resolves #27

11 files changed, 209 insertions, 26 deletions

diff --git a/lib/Makefile.am b/lib/Makefile.am
index 955fa10bb2..6e95ce6397 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -82,7 +82,7 @@ COBJECTS = gnutls_range.c gnutls_record.c \
 	random.c crypto-api.c gnutls_privkey.c gnutls_pcert.c		\
 	gnutls_pubkey.c locks.c gnutls_dtls.c system_override.c	\
 	crypto-backend.c verify-tofu.c pin.c tpm.c fips.c \
-	safe-memset.c inet_pton.c
+	safe-memset.c inet_pton.c auto-verify.c
 
 if ENABLE_SELF_CHECKS
 COBJECTS += crypto-selftests.c crypto-selftests-pk.c
diff --git a/lib/auto-verify.c b/lib/auto-verify.c
new file mode 100644
index 0000000000..1de1442c2b
--- /dev/null
+++ b/lib/auto-verify.c
@@ -0,0 +1,147 @@
+/*
+ * Copyright (C) 2015 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/>
+ *
+ */
+
+#include "gnutls_int.h"
+#include "gnutls_errors.h"
+#include <auth/cert.h>
+#include <gnutls/gnutls.h>
+
+/* This file implements the client certificate auto verification functionality.
+ */
+
+/* The actual verification callback. */
+static int auto_verify_cb(gnutls_session_t session)
+{
+        unsigned int status;
+        int ret;
+
+        if (session->internals.vc_elements == 0) {
+        	ret = gnutls_certificate_verify_peers2(session, &status);
+	} else {
+	        ret = gnutls_certificate_verify_peers(session, session->internals.vc_data,
+						      session->internals.vc_elements, &status);
+        }
+        if (ret < 0) {
+                return gnutls_assert_val(GNUTLS_E_CERTIFICATE_ERROR);
+        }
+
+        session->internals.vc_status = status;
+
+        if (status != 0)        /* Certificate is not trusted */
+                return gnutls_assert_val(GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR);
+
+        /* notify gnutls to continue handshake normally */
+        return 0;
+}
+
+/**
+ * gnutls_session_set_verify_cert:
+ * @session: is a gnutls session
+ * @hostname: is the expected name of the peer; may be %NULL
+ * @flags: flags for certificate verification -- #gnutls_certificate_verify_flags
+ *
+ * This function instructs GnuTLS to verify the peer's certificate
+ * using the provided hostname. If the verification fails the handshake
+ * will also fail with %GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR. In that
+ * case the verification result can be obtained using gnutls_session_get_verify_cert_status().
+ *
+ * The @hostname pointer provided must remain valid for the lifetime
+ * of the session. More precisely it should be available during any subsequent
+ * handshakes. If no hostname is provided, no hostname verification
+ * will be performed. For a more advanced verification function check
+ * gnutls_session_set_verify_cert2().
+ *
+ * The gnutls_session_set_verify_cert() function is intended to be used by TLS
+ * clients to verify the server's certificate.
+ *
+ * Since: 3.5.0
+ **/
+void gnutls_session_set_verify_cert(gnutls_session_t session,
+				     const char *hostname, unsigned flags)
+{
+	if (hostname) {
+		session->internals.vc_sdata.type = GNUTLS_DT_DNS_HOSTNAME;
+		session->internals.vc_sdata.data = (void*)hostname;
+		session->internals.vc_sdata.size = 0;
+		session->internals.vc_elements = 1;
+		session->internals.vc_data = &session->internals.vc_sdata;
+	} else {
+		session->internals.vc_elements = 0;
+	}
+
+	if (flags)
+		session->internals.additional_verify_flags |= flags;
+
+	gnutls_session_set_verify_function(session, auto_verify_cb);
+}
+
+/**
+ * gnutls_session_set_verify_cert2:
+ * @session: is a gnutls session
+ * @data: an array of typed data
+ * @elements: the number of data elements
+ * @flags: flags for certificate verification -- #gnutls_certificate_verify_flags
+ *
+ * This function instructs GnuTLS to verify the peer's certificate
+ * using the provided typed data information. If the verification fails the handshake
+ * will also fail with %GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR. In that
+ * case the verification result can be obtained using gnutls_session_get_verify_cert_status().
+ *
+ * The acceptable typed data are the same as in gnutls_certificate_verify_peers(),
+ * and once set must remain valid for the lifetime of the session. More precisely
+ * they should be available during any subsequent handshakes.
+ *
+ * Since: 3.5.0
+ **/
+void gnutls_session_set_verify_cert2(gnutls_session_t session,
+				     gnutls_typed_vdata_st * data,
+				     unsigned elements,
+				     unsigned flags)
+{
+	session->internals.vc_data = data;
+	session->internals.vc_elements = elements;
+
+	if (flags)
+		session->internals.additional_verify_flags |= flags;
+
+	gnutls_session_set_verify_function(session, auto_verify_cb);
+}
+
+/**
+ * gnutls_session_get_verify_cert_status:
+ * @session: is a gnutls session
+ *
+ * This function returns the status of the verification when initiated
+ * via auto-verification, i.e., by gnutls_session_set_verify_cert2() or
+ * gnutls_session_set_verify_cert(). If no certificate verification
+ * was occurred then the return value would be set to ((unsigned int)-1).
+ *
+ * The certificate verification status is the same as in gnutls_certificate_verify_peers().
+ *
+ * Returns: the certificate verification status.
+ *
+ * Since: 3.5.0
+ **/
+unsigned int gnutls_session_get_verify_cert_status(gnutls_session_t session)
+{
+	return session->internals.vc_status;
+}
diff --git a/lib/gnutls_alert.c b/lib/gnutls_alert.c
index 66270dc18a..1d183930ed 100644
--- a/lib/gnutls_alert.c
+++ b/lib/gnutls_alert.c
@@ -228,6 +228,7 @@ int gnutls_error_to_alert(int err, int *level)
 	case GNUTLS_E_ASN1_SYNTAX_ERROR:
 	case GNUTLS_E_ASN1_DER_OVERFLOW:
 	case GNUTLS_E_CERTIFICATE_ERROR:
+	case GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR:
 		ret = GNUTLS_A_BAD_CERTIFICATE;
 		_level = GNUTLS_AL_FATAL;
 		break;
diff --git a/lib/gnutls_cert.c b/lib/gnutls_cert.c
index 7064aadbf6..bd99c7fc61 100644
--- a/lib/gnutls_cert.c
+++ b/lib/gnutls_cert.c
@@ -600,7 +600,7 @@ _gnutls_openpgp_crt_verify_peers(gnutls_session_t session,
 		return GNUTLS_E_NO_CERTIFICATE_FOUND;
 	}
 
-	verify_flags = cred->verify_flags | session->internals.priorities.additional_verify_flags;
+	verify_flags = cred->verify_flags | session->internals.additional_verify_flags;
 
 	/* generate a list of gnutls_certs based on the auth info
 	 * raw certs.
diff --git a/lib/gnutls_errors.c b/lib/gnutls_errors.c
index 50f2a0ff2c..91a0fa7925 100644
--- a/lib/gnutls_errors.c
+++ b/lib/gnutls_errors.c
@@ -153,6 +153,8 @@ static const gnutls_error_entry error_entries[] = {
 		    GNUTLS_E_RECORD_LIMIT_REACHED),
 	ERROR_ENTRY(N_("Error in the certificate."),
 		    GNUTLS_E_CERTIFICATE_ERROR),
+	ERROR_ENTRY(N_("Error in the certificate verification."),
+		    GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR),
 	ERROR_ENTRY(N_("Could not authenticate peer."),
 		    GNUTLS_E_AUTH_ERROR),
 	ERROR_ENTRY(N_
diff --git a/lib/gnutls_handshake.c b/lib/gnutls_handshake.c
index d8cc93ce15..d28f543345 100644
--- a/lib/gnutls_handshake.c
+++ b/lib/gnutls_handshake.c
@@ -2530,6 +2530,8 @@ int gnutls_handshake(gnutls_session_t session)
 		session->internals.handshake_in_progress = 1;
 
 		gettime(&session->internals.dtls.handshake_start_time);
+		session->internals.vc_status = -1;
+
 		if (session->internals.handshake_timeout_ms &&
 		    session->internals.handshake_endtime == 0)
 			    session->internals.handshake_endtime = session->internals.dtls.handshake_start_time.tv_sec +
diff --git a/lib/gnutls_int.h b/lib/gnutls_int.h
index 3db0e1f699..83b3b5b035 100644
--- a/lib/gnutls_int.h
+++ b/lib/gnutls_int.h
@@ -1,5 +1,6 @@
 /*
- * Copyright (C) 2000-2012 Free Software Foundation, Inc.
+ * Copyright (C) 2000-2015 Free Software Foundation, Inc.
+ * Copyright (C) 2015 Red Hat, Inc.
  *
  * Author: Nikos Mavrogiannopoulos
  *
@@ -1002,6 +1003,11 @@ typedef struct {
 	/* a verify callback to override the verify callback from the credentials
 	 * structure */
 	gnutls_certificate_verify_function *verify_callback;
+	gnutls_typed_vdata_st *vc_data;
+	gnutls_typed_vdata_st vc_sdata;
+	unsigned vc_elements;
+	unsigned vc_status;
+	unsigned int additional_verify_flags; /* may be set by priorities or the vc functions */
 
 	/* If you add anything here, check _gnutls_handshake_internal_state_clear().
 	 */
diff --git a/lib/gnutls_priority.c b/lib/gnutls_priority.c
index f60674c174..72c6d1e3a3 100644
--- a/lib/gnutls_priority.c
+++ b/lib/gnutls_priority.c
@@ -1,5 +1,6 @@
 /*
- * Copyright (C) 2004-2012 Free Software Foundation, Inc.
+ * Copyright (C) 2004-2015 Free Software Foundation, Inc.
+ * Copyright (C) 2015 Red Hat, Inc.
  *
  * Author: Nikos Mavrogiannopoulos
  *
@@ -637,6 +638,8 @@ gnutls_priority_set(gnutls_session_t session, gnutls_priority_t priority)
 	    session->internals.priorities.compression.algorithms == 0)
 		return gnutls_assert_val(GNUTLS_E_NO_PRIORITIES_WERE_SET);
 
+	session->internals.additional_verify_flags |= priority->additional_verify_flags;
+
 	return 0;
 }
 
diff --git a/lib/gnutls_x509.c b/lib/gnutls_x509.c
index 22dea94fdf..648a0b9e5a 100644
--- a/lib/gnutls_x509.c
+++ b/lib/gnutls_x509.c
@@ -224,8 +224,7 @@ _gnutls_x509_cert_verify_peers(gnutls_session_t session,
 	}
 
 	verify_flags =
-	    cred->verify_flags | session->internals.priorities.
-	    additional_verify_flags;
+	    cred->verify_flags | session->internals.additional_verify_flags;
 	/* generate a list of gnutls_certs based on the auth info
 	 * raw certs.
 	 */
diff --git a/lib/includes/gnutls/gnutls.h.in b/lib/includes/gnutls/gnutls.h.in
index c249f7b75f..ffcf04302b 100644
--- a/lib/includes/gnutls/gnutls.h.in
+++ b/lib/includes/gnutls/gnutls.h.in
@@ -1168,6 +1168,45 @@ char *gnutls_session_get_desc(gnutls_session_t session);
 typedef int gnutls_certificate_verify_function(gnutls_session_t);
 void gnutls_session_set_verify_function(gnutls_session_t session, gnutls_certificate_verify_function * func);
 
+/**
+ * gnutls_vdata_types_t:
+ * @GNUTLS_DT_UNKNOWN: Unknown data type.
+ * @GNUTLS_DT_DNS_HOSTNAME: The data contain a null-terminated DNS hostname; the hostname will be 
+ *   matched using the RFC6125 rules.
+ * @GNUTLS_DT_RFC822NAME: The data contain a null-terminated email address; the email will be
+ *   matched against the RFC822Name field of the certificate, or the EMAIL DN component if the
+ *   former isn't available. Prior to matching the email address will be converted to ACE
+ *   (ASCII-compatible-encoding).
+ * @GNUTLS_DT_KEY_PURPOSE_OID: The data contain a null-terminated key purpose OID. It will be matched
+ *   against the certificate's Extended Key Usage extension.
+ *
+ * Enumeration of different typed-data options. They are used as input to certificate
+ * verification functions to provide information about the name and purpose of the
+ * certificate. Only a single option of a type can be provided to the relevant functions.
+ */
+typedef enum {
+	GNUTLS_DT_UNKNOWN = 0,
+	GNUTLS_DT_DNS_HOSTNAME = 1,
+	GNUTLS_DT_KEY_PURPOSE_OID = 2,
+	GNUTLS_DT_RFC822NAME = 3
+} gnutls_vdata_types_t;
+
+typedef struct {
+	gnutls_vdata_types_t type;
+	unsigned char *data;
+	unsigned int size;
+} gnutls_typed_vdata_st;
+
+void gnutls_session_set_verify_cert(gnutls_session_t session,
+			       const char *hostname, unsigned flags);
+
+void
+gnutls_session_set_verify_cert2(gnutls_session_t session,
+				gnutls_typed_vdata_st * data,
+				unsigned elements, unsigned flags);
+
+unsigned int gnutls_session_get_verify_cert_status(gnutls_session_t);
+
 int gnutls_session_set_premaster(gnutls_session_t session,
 				 unsigned int entity,
 				 gnutls_protocol_t version,
@@ -1941,26 +1980,6 @@ int gnutls_certificate_verify_peers3(gnutls_session_t session,
 				     const char *hostname,
 				     unsigned int *status);
 
-/**
- * gnutls_vdata_types_t:
- * @GNUTLS_DT_UNKNOWN: Unknown data type.
- * @GNUTLS_DT_DNS_HOSTNAME: The data contain a null-terminated DNS hostname.
- * @GNUTLS_DT_KEY_PURPOSE_OID: The data contain a null-terminated key purpose OID.
- *
- * Enumeration of different key exchange algorithms.
- */
-typedef enum {
-	GNUTLS_DT_UNKNOWN = 0,
-	GNUTLS_DT_DNS_HOSTNAME = 1,
-	GNUTLS_DT_KEY_PURPOSE_OID = 2
-} gnutls_vdata_types_t;
-
-typedef struct {
-	gnutls_vdata_types_t type;
-	unsigned char *data;
-	unsigned int size;
-} gnutls_typed_vdata_st;
-
 int
 gnutls_certificate_verify_peers(gnutls_session_t session,
 				gnutls_typed_vdata_st * data,
@@ -2346,6 +2365,7 @@ int gnutls_fips140_mode_enabled(void);
 #define GNUTLS_E_AUTH_ERROR -343
 #define GNUTLS_E_NO_APPLICATION_PROTOCOL -344
 #define GNUTLS_E_SOCKETS_INIT_ERROR -345
+#define GNUTLS_E_CERTIFICATE_VERIFICATION_ERROR -348
 
 #define GNUTLS_E_SELF_TEST_ERROR -400
 #define GNUTLS_E_NO_SELF_TEST -401
diff --git a/lib/libgnutls.map b/lib/libgnutls.map
index 8430932682..801b048b81 100644
--- a/lib/libgnutls.map
+++ b/lib/libgnutls.map
@@ -1026,6 +1026,9 @@ GNUTLS_3_1_0 {
 	gnutls_x509_othername_to_virtual;
 	_gnutls_global_init_skip;
 	gnutls_session_set_verify_function;
+	gnutls_session_set_verify_cert;
+	gnutls_session_set_verify_cert2;
+	gnutls_session_get_verify_cert_status;
 } GNUTLS_3_0_0;
 
 GNUTLS_FIPS140 {