Implemented permanent certificate coupling plugin

7 files changed, 449 insertions, 0 deletions

diff --git a/configure.in b/configure.in
index 938afb053..009af124d 100644
--- a/configure.in
+++ b/configure.in
@@ -169,6 +169,7 @@ ARG_ENABL_SET([ha],             [enable high availability cluster plugin.])
 ARG_ENABL_SET([whitelist],      [enable peer identity whitelisting plugin.])
 ARG_ENABL_SET([led],            [enable plugin to control LEDs on IKEv2 activity using the Linux kernel LED subsystem.])
 ARG_ENABL_SET([duplicheck],     [advanced duplicate checking plugin using liveness checks.])
+ARG_ENABL_SET([coupling],       [enable IKEv2 plugin to couple peer certificates permanently to authentication.])
 ARG_ENABL_SET([vstr],           [enforce using the Vstr string library to replace glibc-like printf hooks.])
 ARG_ENABL_SET([monolithic],     [build monolithic version of libstrongswan that includes all enabled plugins. Similarly, the plugins of charon are assembled in libcharon.])
 
@@ -779,6 +780,7 @@ ADD_PLUGIN([ha],                   [c libcharon])
 ADD_PLUGIN([whitelist],            [c libcharon])
 ADD_PLUGIN([led],                  [c libcharon])
 ADD_PLUGIN([duplicheck],           [c libcharon])
+ADD_PLUGIN([coupling],             [c libcharon])
 ADD_PLUGIN([maemo],                [c libcharon])
 ADD_PLUGIN([uci],                  [c libcharon])
 ADD_PLUGIN([addrblock],            [c libcharon])
@@ -860,6 +862,7 @@ AM_CONDITIONAL(USE_HA, test x$ha = xtrue)
 AM_CONDITIONAL(USE_WHITELIST, test x$whitelist = xtrue)
 AM_CONDITIONAL(USE_LED, test x$led = xtrue)
 AM_CONDITIONAL(USE_DUPLICHECK, test x$duplicheck = xtrue)
+AM_CONDITIONAL(USE_COUPLING, test x$coupling = xtrue)
 AM_CONDITIONAL(USE_EAP_SIM, test x$eap_sim = xtrue)
 AM_CONDITIONAL(USE_EAP_SIM_FILE, test x$eap_sim_file = xtrue)
 AM_CONDITIONAL(USE_EAP_SIMAKA_SQL, test x$eap_simaka_sql = xtrue)
@@ -1043,6 +1046,7 @@ AC_OUTPUT(
 	src/libcharon/plugins/whitelist/Makefile
 	src/libcharon/plugins/led/Makefile
 	src/libcharon/plugins/duplicheck/Makefile
+	src/libcharon/plugins/coupling/Makefile
 	src/libcharon/plugins/android/Makefile
 	src/libcharon/plugins/maemo/Makefile
 	src/libcharon/plugins/stroke/Makefile
diff --git a/src/libcharon/Makefile.am b/src/libcharon/Makefile.am
index 8a4f8917d..a995cae9c 100644
--- a/src/libcharon/Makefile.am
+++ b/src/libcharon/Makefile.am
@@ -424,6 +424,13 @@ if MONOLITHIC
 endif
 endif
 
+if USE_COUPLING
+  SUBDIRS += plugins/coupling
+if MONOLITHIC
+  libcharon_la_LIBADD += plugins/coupling/libstrongswan-coupling.la
+endif
+endif
+
 if USE_UCI
   SUBDIRS += plugins/uci
 if MONOLITHIC
diff --git a/src/libcharon/plugins/coupling/Makefile.am b/src/libcharon/plugins/coupling/Makefile.am
new file mode 100644
index 000000000..642ce820c
--- /dev/null
+++ b/src/libcharon/plugins/coupling/Makefile.am
@@ -0,0 +1,16 @@
+
+INCLUDES = -I$(top_srcdir)/src/libstrongswan -I$(top_srcdir)/src/libhydra \
+	-I$(top_srcdir)/src/libcharon
+
+AM_CFLAGS = -rdynamic
+
+if MONOLITHIC
+noinst_LTLIBRARIES = libstrongswan-coupling.la
+else
+plugin_LTLIBRARIES = libstrongswan-coupling.la
+endif
+
+libstrongswan_coupling_la_SOURCES = coupling_plugin.h coupling_plugin.c \
+	coupling_validator.h coupling_validator.c
+
+libstrongswan_coupling_la_LDFLAGS = -module -avoid-version
diff --git a/src/libcharon/plugins/coupling/coupling_plugin.c b/src/libcharon/plugins/coupling/coupling_plugin.c
new file mode 100644
index 000000000..8e0705c2e
--- /dev/null
+++ b/src/libcharon/plugins/coupling/coupling_plugin.c
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2011 Martin Willi
+ * Copyright (C) 2011 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program 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 General Public License
+ * for more details.
+ */
+
+#include "coupling_plugin.h"
+
+#include "coupling_validator.h"
+
+#include <daemon.h>
+
+typedef struct private_coupling_plugin_t private_coupling_plugin_t;
+
+/**
+ * private data of coupling plugin
+ */
+struct private_coupling_plugin_t {
+
+	/**
+	 * implements plugin interface
+	 */
+	coupling_plugin_t public;
+
+	/**
+	 * validator controlling couplings
+	 */
+	coupling_validator_t *validator;
+};
+
+METHOD(plugin_t, destroy, void,
+	private_coupling_plugin_t *this)
+{
+	lib->credmgr->remove_validator(lib->credmgr, &this->validator->validator);
+	this->validator->destroy(this->validator);
+	free(this);
+}
+
+/**
+ * Plugin constructor
+ */
+plugin_t *coupling_plugin_create()
+{
+	private_coupling_plugin_t *this;
+
+	INIT(this,
+		.public = {
+			.plugin = {
+				.destroy = _destroy,
+			},
+		},
+		.validator = coupling_validator_create(),
+	);
+
+	if (!this->validator)
+	{
+		free(this);
+		return NULL;
+	}
+
+	lib->credmgr->add_validator(lib->credmgr, &this->validator->validator);
+
+	return &this->public.plugin;
+}
diff --git a/src/libcharon/plugins/coupling/coupling_plugin.h b/src/libcharon/plugins/coupling/coupling_plugin.h
new file mode 100644
index 000000000..645100b45
--- /dev/null
+++ b/src/libcharon/plugins/coupling/coupling_plugin.h
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2011 Martin Willi
+ * Copyright (C) 2011 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program 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 General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup coupling coupling
+ * @ingroup cplugins
+ *
+ * @defgroup coupling_plugin coupling_plugin
+ * @{ @ingroup coupling
+ */
+
+#ifndef COUPLING_PLUGIN_H_
+#define COUPLING_PLUGIN_H_
+
+#include <plugins/plugin.h>
+
+typedef struct coupling_plugin_t coupling_plugin_t;
+
+/**
+ * Plugin to couple peer certificates permanently to peer authentication.
+ */
+struct coupling_plugin_t {
+
+	/**
+	 * implements plugin interface
+	 */
+	plugin_t plugin;
+};
+
+#endif /** COUPLING_PLUGIN_H_ @}*/
diff --git a/src/libcharon/plugins/coupling/coupling_validator.c b/src/libcharon/plugins/coupling/coupling_validator.c
new file mode 100644
index 000000000..06b6f7d86
--- /dev/null
+++ b/src/libcharon/plugins/coupling/coupling_validator.c
@@ -0,0 +1,258 @@
+/*
+ * Copyright (C) 2011 Martin Willi
+ * Copyright (C) 2011 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program 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 General Public License
+ * for more details.
+ */
+
+#include "coupling_validator.h"
+
+#include <errno.h>
+#include <time.h>
+
+#include <daemon.h>
+#include <threading/mutex.h>
+
+/* buffer size for hex-encoded hash */
+#define MAX_HASH_SIZE (HASH_SIZE_SHA512 * 2 + 1)
+
+typedef struct private_coupling_validator_t private_coupling_validator_t;
+
+/**
+ * Private data of an coupling_validator_t object.
+ */
+struct private_coupling_validator_t {
+
+	/**
+	 * Public coupling_validator_t interface.
+	 */
+	coupling_validator_t public;
+
+	/**
+	 * Mutex
+	 */
+	mutex_t *mutex;
+
+	/**
+	 * File with device couplings
+	 */
+	FILE *f;
+
+	/**
+	 * Hasher to create hashes
+	 */
+	hasher_t *hasher;
+
+	/**
+	 * maximum number of couplings
+	 */
+	int max_couplings;
+};
+
+/**
+ * Get hash of a certificate
+ */
+static bool get_cert_hash(private_coupling_validator_t *this,
+						  certificate_t *cert, char *hex)
+{
+	char buf[MAX_HASH_SIZE];
+	chunk_t encoding;
+
+	if (!cert->get_encoding(cert, CERT_ASN1_DER, &encoding))
+	{
+		return FALSE;
+	}
+	this->hasher->get_hash(this->hasher, encoding, buf);
+	free(encoding.ptr);
+	chunk_to_hex(chunk_create(buf, this->hasher->get_hash_size(this->hasher)),
+				 hex, FALSE);
+	return TRUE;
+}
+
+/**
+ * Check if we have an entry for a given hash
+ */
+static bool has_entry(private_coupling_validator_t *this, char *hash)
+{
+	char line[256];
+	int hash_len;
+
+	hash_len = strlen(hash);
+	rewind(this->f);
+
+	while (fgets(line, sizeof(line), this->f))
+	{
+		if (strlen(line) >= hash_len &&
+			strncaseeq(line, hash, hash_len))
+		{
+			return TRUE;
+		}
+	}
+	return FALSE;
+}
+
+/**
+ * Get the number of coupling entries we currently have
+ */
+static int get_number_of_entries(private_coupling_validator_t *this)
+{
+	char line[256];
+	int count = 0;
+
+	rewind(this->f);
+
+	while (fgets(line, sizeof(line), this->f))
+	{
+		/* valid entries start with hex encoded hash */
+		if (strchr("1234567890abcdefABCDEF", line[0]))
+		{
+			count++;
+		}
+	}
+	return count;
+}
+
+/**
+ * Add a new entry to the file
+ */
+static bool add_entry(private_coupling_validator_t *this, char *hash,
+					  identification_t *id)
+{
+	return fseek(this->f, 0, SEEK_END) == 0 &&
+		   fprintf(this->f, "%s %u '%Y'\n", hash, time(NULL), id) > 0;
+}
+
+METHOD(cert_validator_t, validate, bool,
+	private_coupling_validator_t *this,
+	certificate_t *subject, certificate_t *issuer,
+	bool online, u_int pathlen, bool anchor, auth_cfg_t *auth)
+{
+	bool valid = FALSE;
+	char hash[MAX_HASH_SIZE];
+
+	if (pathlen != 0)
+	{
+		return TRUE;
+	}
+	if (get_cert_hash(this, subject, hash))
+	{
+		this->mutex->lock(this->mutex);
+		if (has_entry(this, hash))
+		{
+			DBG1(DBG_CFG, "coupled certificate '%Y' found, accepted",
+				 subject->get_subject(subject));
+			valid = TRUE;
+		}
+		else if (get_number_of_entries(this) < this->max_couplings)
+		{
+			if (add_entry(this, hash, subject->get_subject(subject)))
+			{
+				DBG1(DBG_CFG, "coupled new certificate '%Y'",
+					 subject->get_subject(subject));
+				valid = TRUE;
+			}
+			else
+			{
+				DBG1(DBG_CFG, "coupling new certificate '%Y' failed",
+					 subject->get_subject(subject));
+			}
+		}
+		else
+		{
+			DBG1(DBG_CFG, "coupling new certificate '%Y' failed, limit of %d "
+				 "couplings reached", subject->get_subject(subject),
+				 this->max_couplings);
+		}
+		this->mutex->unlock(this->mutex);
+	}
+	return valid;
+}
+
+METHOD(coupling_validator_t, destroy, void,
+	private_coupling_validator_t *this)
+{
+	if (this->f)
+	{
+		fclose(this->f);
+	}
+	DESTROY_IF(this->hasher);
+	this->mutex->destroy(this->mutex);
+	free(this);
+}
+
+/**
+ * See header
+ */
+coupling_validator_t *coupling_validator_create()
+{
+	private_coupling_validator_t *this;
+	char *path, *hash;
+	int i;
+	struct {
+		hash_algorithm_t alg;
+		char *name;
+	} hash_types[] = {
+		{ HASH_MD5,		"md5"},
+		{ HASH_SHA1,	"sha1"},
+		{ HASH_SHA256,	"sha256"},
+		{ HASH_SHA384,	"sha384"},
+		{ HASH_SHA512,	"sha512"},
+	};
+
+	INIT(this,
+		.public = {
+			.validator = {
+				.validate = _validate,
+			},
+			.destroy = _destroy,
+		},
+		.mutex = mutex_create(MUTEX_TYPE_DEFAULT),
+		.max_couplings = lib->settings->get_int(lib->settings,
+									  "charon.plugins.coupling.max", 1),
+	);
+
+	hash = lib->settings->get_str(lib->settings,
+								  "charon.plugins.coupling.hash", "sha1");
+	for (i = 0; i < countof(hash_types); i++)
+	{
+		if (strcaseeq(hash_types[i].name, hash))
+		{
+			this->hasher = lib->crypto->create_hasher(lib->crypto,
+													  hash_types[i].alg);
+			break;
+		}
+	}
+	if (!this->hasher)
+	{
+		DBG1(DBG_CFG, "unsupported coupling hash algorithm: %s", hash);
+		destroy(this);
+		return NULL;
+	}
+
+	path = lib->settings->get_str(lib->settings,
+								  "charon.plugins.coupling.file", NULL);
+	if (!path)
+	{
+		DBG1(DBG_CFG, "coupling file path unspecified");
+		destroy(this);
+		return NULL;
+	}
+	this->f = fopen(path, "a+");
+	if (!this->f)
+	{
+		DBG1(DBG_CFG, "opening coupling file '%s' failed: %s",
+			 path, strerror(errno));
+		destroy(this);
+		return NULL;
+	}
+	setlinebuf(this->f);
+	return &this->public;
+}
diff --git a/src/libcharon/plugins/coupling/coupling_validator.h b/src/libcharon/plugins/coupling/coupling_validator.h
new file mode 100644
index 000000000..d6b4d3718
--- /dev/null
+++ b/src/libcharon/plugins/coupling/coupling_validator.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2011 Martin Willi
+ * Copyright (C) 2011 revosec AG
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2 of the License, or (at your
+ * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
+ *
+ * This program 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 General Public License
+ * for more details.
+ */
+
+/**
+ * @defgroup coupling_validator coupling_validator
+ * @{ @ingroup coupling
+ */
+
+#ifndef COUPLING_VALIDATOR_H_
+#define COUPLING_VALIDATOR_H_
+
+#include <credentials/cert_validator.h>
+
+typedef struct coupling_validator_t coupling_validator_t;
+
+/**
+ * Validator that couples authenticated certificates permanently.
+ */
+struct coupling_validator_t {
+
+	/**
+	 * Implements cert_validator_t interface.
+	 */
+	cert_validator_t validator;
+
+	/**
+	 * Destroy a coupling_validator_t.
+	 */
+	void (*destroy)(coupling_validator_t *this);
+};
+
+/**
+ * Create a coupling_validator instance.
+ */
+coupling_validator_t *coupling_validator_create();
+
+#endif /** COUPLING_VALIDATOR_H_ @}*/