This patch builds on the "Export secure_memzero() to plug-ins" patch and
adds export of openvpn_base64_encode() and openvpn_base64_decode()
This also ships with a very simple plug-in which demonstrates how to use
the new exported functions.
Signed-off-by: David Sommerseth <dav...@openvpn.net>
---
include/openvpn-plugin.h.in | 31 ++++++
sample/sample-plugins/simple/base64.c | 204 ++++++++++++++++++++++++++++++++++
src/openvpn/plugin.c | 5 +-
3 files changed, 239 insertions(+), 1 deletion(-)
create mode 100644 sample/sample-plugins/simple/base64.c
diff --git a/include/openvpn-plugin.h.in b/include/openvpn-plugin.h.in
index ec83f3a6..68180d62 100644
--- a/include/openvpn-plugin.h.in
+++ b/include/openvpn-plugin.h.in
@@ -221,6 +221,8 @@ struct openvpn_plugin_string_list
* OpenVPN to plug-ins.
*
* 4 Exported secure_memzero() as plugin_secure_memzero()
+ * Exported openvpn_base64_encode() as plugin_base64_encode()
+ * Exported openvpn_base64_decode() as plugin_base64_decode()
*/
#define OPENVPN_PLUGINv3_STRUCTVER 4
@@ -269,6 +271,33 @@ typedef void (*plugin_vlog_t)(openvpn_plugin_log_flags_t
flags,
*/
typedef void (*plugin_secure_memzero_t)(void *data, size_t len);
+/**
+ * Export of openvpn_base64_encode() to be used inside plug-ins
+ *
+ * @param data Pointer to data to BASE64 encode
+ * @param size Length of data, in bytes
+ * @param *str Pointer to the return buffer. This needed memory is
+ * allocated by openvpn_base64_encode() and needs to be free()d
+ * after use.
+ *
+ * @return int Returns the length of the buffer created, or -1 on error.
+ *
+ */
+typedef int (*plugin_base64_encode_t)(const void *data, int size, char **str);
+
+/**
+ * Export of openvpn_base64_decode() to be used inside plug-ins
+ *
+ * @param str Pointer to the BASE64 encoded data
+ * @param data Pointer to the buffer where save the decoded data
+ * @param size Size of the destination buffer
+ *
+ * @return int Returns the length of the decoded data, or -1 on error or
+ * if the destination buffer is too small.
+ *
+ */
+typedef int (*plugin_base64_decode_t)(const char *str, void *data, int size);
+
/**
* Used by the openvpn_plugin_open_v3() function to pass callback
@@ -291,6 +320,8 @@ struct openvpn_plugin_callbacks
plugin_log_t plugin_log;
plugin_vlog_t plugin_vlog;
plugin_secure_memzero_t plugin_secure_memzero;
+ plugin_base64_encode_t plugin_base64_encode;
+ plugin_base64_decode_t plugin_base64_decode;
};
/**
diff --git a/sample/sample-plugins/simple/base64.c
b/sample/sample-plugins/simple/base64.c
new file mode 100644
index 00000000..503b5ba0
--- /dev/null
+++ b/sample/sample-plugins/simple/base64.c
@@ -0,0 +1,204 @@
+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single TCP/UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2017 David Sommerseth <dav...@openvpn.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program (see the file COPYING included with this
+ * distribution); if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#include "openvpn-plugin.h"
+
+#define PLUGIN_NAME "base64.c"
+
+/* Exported plug-in v3 API functions */
+plugin_log_t ovpn_log = NULL; /**< Pointer to the OpenVPN
log function. See plugin_log() */
+plugin_vlog_t ovpn_vlog = NULL; /**< Pointer to the OpenVPN
vlog function. See plugin_vlog() */
+plugin_base64_encode_t ovpn_base64_encode = NULL; /**< Pointer to the
openvpn_base64_encode () function */
+plugin_base64_decode_t ovpn_base64_decode = NULL; /**< Pointer to the
openvpn_base64_decode () function */
+
+/**
+ * Search the environment pointer for a specific env var name
+ *
+ * PLEASE NOTE! The result is not valid outside the local
+ * scope of the calling function. Once the calling function
+ * returns, any returned pointers are invalid.
+ *
+ * @param name String containing the env.var name to search for
+ * @param envp String array pointer to the environment variable
+ *
+ * @return Returns a pointer to the value in the environment variable
+ * table on successful match. Otherwise NULL is returned
+ *
+ */
+static const char *
+get_env(const char *name, const char *envp[])
+{
+ if (envp)
+ {
+ int i;
+ const int namelen = strlen(name);
+ for (i = 0; envp[i]; ++i)
+ {
+ if (!strncmp(envp[i], name, namelen))
+ {
+ const char *cp = envp[i] + namelen;
+ if (*cp == '=')
+ {
+ return cp + 1;
+ }
+ }
+ }
+ }
+ return NULL;
+}
+
+
+/**
+ * This function is called when OpenVPN loads the plug-in.
+ * The purpose is to initialize the plug-in and tell OpenVPN
+ * which plug-in hooks this plug-in wants to be involved in
+ *
+ * For the arguments, see the include/openvpn-plugin.h file
+ * for details on the function parameters
+ *
+ * @param v3structver An integer containing the API version of
+ * the plug-in structs OpenVPN uses
+ * @param args A pointer to the argument struct for
+ * information and features provided by
+ * OpenVPN to the plug-in
+ * @param ret A pointer to the struct OpenVPN uses to
+ * receive information back from the plug-in
+ *
+ * @return Must return OPENVPN_PLUGIN_FUNC_SUCCESS when everything
+ * completed successfully. Otherwise it must be returned
+ * OPENVPN_PLUGIN_FUNC_ERROR, which will stop OpenVPN
+ * from running
+ *
+ */
+OPENVPN_EXPORT int
+openvpn_plugin_open_v3(const int v3structver,
+ struct openvpn_plugin_args_open_in const *args,
+ struct openvpn_plugin_args_open_return *ret)
+{
+ /* Check that we are API compatible */
+ if (v3structver != OPENVPN_PLUGINv3_STRUCTVER)
+ {
+ printf("base64.c: ** ERROR ** Incompatible plug-in interface between
this plug-in and OpenVPN\n");
+ return OPENVPN_PLUGIN_FUNC_ERROR;
+ }
+
+ /* Which callbacks to intercept. */
+ ret->type_mask =
+ OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_TLS_VERIFY)
+ |OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_CONNECT_V2);
+
+ /* we don't need a plug-in context in this example, but OpenVPN expects
"something" */
+ ret->handle = calloc(1, 1);
+
+ /* Hook into the exported functions from OpenVPN */
+ ovpn_log = args->callbacks->plugin_log;
+ ovpn_vlog = args->callbacks->plugin_vlog;
+ ovpn_base64_encode = args->callbacks->plugin_base64_encode;
+ ovpn_base64_decode = args->callbacks->plugin_base64_decode;
+
+ /* Print some version information about the OpenVPN process using this
plug-in */
+ ovpn_log(PLOG_NOTE, PLUGIN_NAME, "OpenVPN %s (Major: %i, Minor: %i,
Patch: %s)\n",
+ args->ovpn_version, args->ovpn_version_major,
+ args->ovpn_version_minor, args->ovpn_version_patch);
+
+ return OPENVPN_PLUGIN_FUNC_SUCCESS;
+}
+
+
+/**
+ * This function is called by OpenVPN each time the OpenVPN reaches
+ * a point where plug-in calls should happen. It only happens for those
+ * plug-in hooks enabled in openvpn_plugin_open_v3().
+ *
+ * For the arguments, see the include/openvpn-plugin.h file
+ * for details on the function parameters
+ *
+ * @param args Pointer to a struct with details about the plug-in
+ * call from the main OpenVPN process.
+ * @param returndata Pointer to a struct where the plug-in can provide
+ * information back to OpenVPN to be processed
+ *
+ * @return Must return OPENVPN_PLUGIN_FUNC_SUCCESS or
+ * OPENVPN_PLUGIN_FUNC_DEFERRED on success. Otherwise it
+ * should return OPENVPN_FUNC_ERROR, which will stop and reject
+ * the client session from progressing.
+ *
+ */
+
+OPENVPN_EXPORT int
+openvpn_plugin_func_v1(openvpn_plugin_handle_t handle, const int type, const
char *argv[], const char *envp[])
+{
+ if (type != OPENVPN_PLUGIN_TLS_VERIFY
+ && type != OPENVPN_PLUGIN_CLIENT_CONNECT_V2)
+ {
+ ovpn_log(PLOG_ERR, PLUGIN_NAME, "Unsupported plug-in hook call
attempted");
+ return OPENVPN_PLUGIN_FUNC_ERROR;
+ }
+
+ /* get username/password from envp string array */
+ const char *clcert_cn = get_env("X509_0_CN", envp);
+ if (!clcert_cn)
+ {
+ /* Ignore certificate checks not being a client certificate */
+ return OPENVPN_PLUGIN_FUNC_SUCCESS;
+ }
+
+ /* test the BAS64 encode function */
+ char *buf = NULL;
+ int r = ovpn_base64_encode(clcert_cn, strlen(clcert_cn), &buf);
+ ovpn_log(PLOG_NOTE, PLUGIN_NAME, "BASE64 encoded '%s' (return value %i):
'%s'",
+ clcert_cn, r, buf);
+
+ /* test the BAS64 encode function */
+ char buf2[256] = {0};
+ r = ovpn_base64_decode(buf, &buf2, 255);
+ ovpn_log(PLOG_NOTE, PLUGIN_NAME, "BASE64 decoded '%s' (return value %i):
'%s'",
+ buf, r, buf2);
+
+ /* Verify the result, and free the buffer allocated by
ovpn_base64_encode() */
+ r = strcmp(clcert_cn, buf2);
+ free(buf);
+
+ return (r == 0) ? OPENVPN_PLUGIN_FUNC_SUCCESS : OPENVPN_PLUGIN_FUNC_ERROR;
+}
+
+
+/**
+ * This cleans up the last part of the plug-in, allows it to
+ * shut down cleanly and release the plug-in global context buffer
+ *
+ * @param handle Pointer to the plug-in global context buffer, which
+ * need to be released by this function
+ */
+OPENVPN_EXPORT void
+openvpn_plugin_close_v1(openvpn_plugin_handle_t handle)
+{
+ struct plugin_context *context = (struct plugin_context *) handle;
+ free(context);
+}
+
diff --git a/src/openvpn/plugin.c b/src/openvpn/plugin.c
index a652d528..ca278af1 100644
--- a/src/openvpn/plugin.c
+++ b/src/openvpn/plugin.c
@@ -44,6 +44,7 @@
#include "misc.h"
#include "plugin.h"
#include "ssl_backend.h"
+#include "base64.h"
#include "win32.h"
#include "memdbg.h"
@@ -411,7 +412,9 @@ plugin_log(openvpn_plugin_log_flags_t flags, const char
*name, const char *forma
static struct openvpn_plugin_callbacks callbacks = {
plugin_log,
plugin_vlog,
- secure_memzero /* plugin_secure_memzero */
+ secure_memzero, /* plugin_secure_memzero */
+ openvpn_base64_encode, /* plugin_base64_encode */
+ openvpn_base64_decode, /* plugin_base64_decode */
};
--
2.11.0
------------------------------------------------------------------------------
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