From: David Sommerseth <dav...@openvpn.net>
This plugin allows setting username/passwords as well as configure
deferred authentication behaviour as part of the runtime initialization.
With this plug-in it is easier to test various scenarios where multiple
authentication plug-ins are active on the server side.
A test documentation was also added to describe various test cases and
the expected results.
Signed-off-by: David Sommerseth <dav...@openvpn.net>
---
v2 - Flipped NULL==var to var==NULL
---
doc/tests/authentication-plugins.md | 153 +++++++++
sample/sample-plugins/Makefile.plugins | 1 +
sample/sample-plugins/defer/multi-auth.c | 413 +++++++++++++++++++++++
3 files changed, 567 insertions(+)
create mode 100644 doc/tests/authentication-plugins.md
create mode 100644 sample/sample-plugins/defer/multi-auth.c
diff --git a/doc/tests/authentication-plugins.md
b/doc/tests/authentication-plugins.md
new file mode 100644
index 00000000..1f5fb851
--- /dev/null
+++ b/doc/tests/authentication-plugins.md
@@ -0,0 +1,153 @@
+# TESTING OF MULTIPLE AUTHENTICATION PLUG-INS
+
+
+OpenVPN 2.x can support loading and authenticating users through multiple
+plug-ins at the same time. But it can only support a single plug-in doing
+deferred authentication. However, a plug-in supporting deferred
+authentication may be accompanied by other authentication plug-ins **not**
+doing deferred authentication.
+
+This is a test script useful to test the various combinations and order of
+plug-in execution.
+
+The configuration files are expected to be used from the root of the build
+directory.
+
+To build the needed authentication plug-in, run:
+
+ make -C sample/sample-plugins
+
+
+## Test configs
+
+* Client config
+
+ verb 4
+ dev tun
+ client
+ remote x.x.x.x
+ ca sample/sample-keys/ca.crt
+ cert sample/sample-keys/client.crt
+ key sample/sample-keys/client.key
+ auth-user-pass
+
+* Base server config (`base-server.conf`)
+
+ verb 4
+ dev tun
+ server 10.8.0.0 255.255.255.0
+ dh sample/sample-keys/dh2048.pem
+ ca sample/sample-keys/ca.crt
+ cert sample/sample-keys/server.crt
+ key sample/sample-keys/server.key
+
+
+## Test cases
+
+### Test: *sanity-1*
+
+This tests the basic authentication with an instant answer.
+
+ config base-server.conf
+ plugin multi-auth.so S1.1 0 foo bar
+
+#### Expected results
+ - Username/password `foo`/`bar`: **PASS**
+ - Anything else: **FAIL**
+
+
+### Test: *sanity-2*
+
+This is similar to `sanity-1`, but does the authentication
+through two plug-ins providing an instant reply.
+
+ config base-server.conf
+ plugin multi-auth.so S2.1 0 foo bar
+ plugin multi-auth.so S2.2 0 foo bar
+
+#### Expected results
+ - Username/password `foo`/`bar`: **PASS**
+ - Anything else: **FAIL**
+
+
+### Test: *sanity-3*
+
+This is also similar to `sanity-1`, but uses deferred authentication
+with a 1 second delay on the response.
+
+ plugin multi-auth.so S3.1 1000 foo bar
+
+#### Expected results
+ - Username/password `foo`/`bar`: **PASS**
+ - Anything else: **FAIL**
+
+
+### Test: *case-a*
+
+Runs two authentications, the first one deferred by 1 second and the
+second one providing an instant response.
+
+ plugin multi-auth.so A.1 1000 foo bar
+ plugin multi-auth.so A.2 0 foo bar
+
+#### Expected results
+ - Username/password `foo`/`bar`: **PASS**
+ - Anything else: **FAIL**
+
+
+### Test: *case-b*
+
+This is similar to `case-a`, but the instant authentication response
+is provided first before the deferred authentication.
+
+ plugin multi-auth.so B.1 0 foo bar
+ plugin multi-auth.so B.2 1000 test pass
+
+#### Expected results
+ - **Always FAIL**
+ - This test should never pass, as each plug-in expects different
+ usernames and passwords.
+
+
+### Test: *case-c*
+
+This is similar to the two prior tests, but the authentication result
+is returned instantly in both steps.
+
+ plugin multi-auth.so C.1 0 foo bar
+ plugin multi-auth.so C.2 0 foo2 bar2
+
+#### Expected results
+ - **Always FAIL**
+ - This test should never pass, as each plug-in expects different
+ usernames and passwords.
+
+
+### Test: *case-d*
+
+This is similar to the `case-b` test, but the order of deferred
+and instant response is reversed.
+
+ plugin ./multi-auth.so D.1 2000 test pass
+ plugin ./multi-auth.so D.2 0 foo bar
+
+#### Expected results
+ - **Always FAIL**
+ - This test should never pass, as each plug-in expects different
+ usernames and passwords.
+
+
+### Test: *case-e*
+
+This test case will run two deferred authentication plug-ins. This is
+**not** supported by OpenVPN, and should therefore fail instantly.
+
+ plugin ./multi-auth.so E1 1000 test1 pass1
+ plugin ./multi-auth.so E2 2000 test2 pass2
+
+#### Expected results
+ - The OpenVPN server process should stop running
+ - An error about multiple deferred plug-ins being configured
+ should be seen in the server log.
+
+
diff --git a/sample/sample-plugins/Makefile.plugins
b/sample/sample-plugins/Makefile.plugins
index 73ce5916..8bfbad09 100644
--- a/sample/sample-plugins/Makefile.plugins
+++ b/sample/sample-plugins/Makefile.plugins
@@ -8,6 +8,7 @@
#
PLUGINS = \
defer/simple \
+ defer/multi-auth \
keying-material-exporter-demo/keyingmaterialexporter \
log/log log/log_v3 \
simple/base64 \
diff --git a/sample/sample-plugins/defer/multi-auth.c
b/sample/sample-plugins/defer/multi-auth.c
new file mode 100644
index 00000000..20c9dac5
--- /dev/null
+++ b/sample/sample-plugins/defer/multi-auth.c
@@ -0,0 +1,413 @@
+/*
+ * 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) 2002-2021 OpenVPN Inc <sa...@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; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/*
+ * This file implements a simple OpenVPN plugin module which
+ * can do either an instant authentication or a deferred auth.
+ * The purpose of this plug-in is to test multiple auth plugins
+ * in the same configuration file
+ *
+ * Plugin arguments:
+ *
+ * multi-auth.so LOG_ID DEFER_TIME USERNAME PASSWORD
+ *
+ * LOG_ID is just an ID string used to separate auth results in the log
+ * DEFER_TIME is the time to defer the auth. Set to 0 to return immediately
+ * USERNAME is the username for a valid authentication
+ * PASSWORD is the password for a valid authentication
+ *
+ * The DEFER_TIME time unit is in ms.
+ *
+ * Sample usage:
+ *
+ * plugin multi-auth.so MA_1 0 foo bar # Instant reply user:foo pass:bar
+ * plugin multi-auth.so MA_2 5000 fux bax # Defer 5 sec, user:fux pass: bax
+ *
+ */
+#include "config.h"
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <unistd.h>
+#include <stdbool.h>
+#include <fcntl.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+
+#include "openvpn-plugin.h"
+
+static char *MODULE = "multi-auth";
+
+/*
+ * Our context, where we keep our state.
+ */
+
+struct plugin_context {
+ int test_deferred_auth;
+ char *authid;
+ char *test_valid_user;
+ char *test_valid_pass;
+};
+
+/* local wrapping of the log function, to add more details */
+static plugin_vlog_t _plugin_vlog_func = NULL;
+static void plog(const struct plugin_context *ctx, int flags, char *fmt, ...)
+{
+ char logid[129];
+
+ if (ctx && ctx->authid)
+ {
+ snprintf(logid, 128, "%s[%s]", MODULE, ctx->authid);
+ }
+ else
+ {
+ snprintf(logid, 128, "%s", MODULE);
+ }
+
+ va_list arglist;
+ va_start(arglist, fmt);
+ _plugin_vlog_func(flags, logid, fmt, arglist);
+ va_end(arglist);
+}
+
+
+/*
+ * Constants indicating minimum API and struct versions by the functions
+ * in this plugin. Consult openvpn-plugin.h, look for:
+ * OPENVPN_PLUGIN_VERSION and OPENVPN_PLUGINv3_STRUCTVER
+ *
+ * Strictly speaking, this sample code only requires plugin_log, a feature
+ * of structver version 1. However, '1' lines up with ancient versions
+ * of openvpn that are past end-of-support. As such, we are requiring
+ * structver '5' here to indicate a desire for modern openvpn, rather
+ * than a need for any particular feature found in structver beyond '1'.
+ */
+#define OPENVPN_PLUGIN_VERSION_MIN 3
+#define OPENVPN_PLUGIN_STRUCTVER_MIN 5
+
+
+struct plugin_per_client_context {
+ int n_calls;
+ bool generated_pf_file;
+};
+
+
+/*
+ * Given an environmental variable name, search
+ * the envp array for its value, returning it
+ * if found or NULL otherwise.
+ */
+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;
+}
+
+/* used for safe printf of possible NULL strings */
+static const char *
+np(const char *str)
+{
+ if (str)
+ {
+ return str;
+ }
+ else
+ {
+ return "[NULL]";
+ }
+}
+
+static int
+atoi_null0(const char *str)
+{
+ if (str)
+ {
+ return atoi(str);
+ }
+ else
+ {
+ return 0;
+ }
+}
+
+/* Require a minimum OpenVPN Plugin API */
+OPENVPN_EXPORT int
+openvpn_plugin_min_version_required_v1()
+{
+ return OPENVPN_PLUGIN_VERSION_MIN;
+}
+
+/* use v3 functions so we can use openvpn's logging and base64 etc. */
+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)
+{
+ if (v3structver < OPENVPN_PLUGIN_STRUCTVER_MIN)
+ {
+ fprintf(stderr, "%s: this plugin is incompatible with the running
version of OpenVPN\n", MODULE);
+ return OPENVPN_PLUGIN_FUNC_ERROR;
+ }
+
+ /* Save global pointers to functions exported from openvpn */
+ _plugin_vlog_func = args->callbacks->plugin_vlog;
+
+ plog(NULL, PLOG_NOTE, "FUNC: openvpn_plugin_open_v3");
+
+ /*
+ * Allocate our context
+ */
+ struct plugin_context *context = NULL;
+ context = (struct plugin_context *) calloc(1, sizeof(struct
plugin_context));
+ if (!context)
+ {
+ goto error;
+ }
+
+ /* simple module argument parsing */
+ if ((args->argv[4]) && !args->argv[5])
+ {
+ context->authid = strdup(args->argv[1]);
+ context->test_deferred_auth = atoi_null0(args->argv[2]);
+ context->test_valid_user = strdup(args->argv[3]);
+ context->test_valid_pass = strdup(args->argv[4]);
+ }
+ else
+ {
+ plog(context, PLOG_ERR, "Too many arguments provided");
+ goto error;
+ }
+
+ if (context->test_deferred_auth > 0)
+ {
+ plog(context, PLOG_NOTE, "TEST_DEFERRED_AUTH %d",
context->test_deferred_auth);
+ }
+
+ /*
+ * Which callbacks to intercept.
+ */
+ ret->type_mask = OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY);
+ ret->handle = (openvpn_plugin_handle_t *) context;
+
+ plog(context, PLOG_NOTE, "initialization succeeded");
+ return OPENVPN_PLUGIN_FUNC_SUCCESS;
+
+error:
+ plog(context, PLOG_NOTE, "initialization failed");
+ if (context)
+ {
+ free(context);
+ }
+ return OPENVPN_PLUGIN_FUNC_ERROR;
+}
+
+static bool
+do_auth_user_pass(struct plugin_context *context,
+ const char *username, const char *password)
+{
+ plog(context, PLOG_NOTE,
+ "expect_user=%s, received_user=%s, expect_passw=%s, received_passw=%s",
+ np(context->test_valid_user),
+ np(username),
+ np(context->test_valid_pass),
+ np(password));
+
+ if (context->test_valid_user && context->test_valid_pass)
+ {
+ if ((strcmp(context->test_valid_user, username) != 0)
+ || (strcmp(context->test_valid_pass, password) != 0))
+ {
+ plog(context, PLOG_ERR,
+ "User/Password auth result: FAIL");
+ return false;
+ }
+ else
+ {
+ plog(context, PLOG_NOTE,
+ "User/Password auth result: PASS");
+ return true;
+ }
+ }
+ return false;
+}
+
+
+static int
+auth_user_pass_verify(struct plugin_context *context,
+ struct plugin_per_client_context *pcc,
+ const char *argv[], const char *envp[])
+{
+ /* get username/password from envp string array */
+ const char *username = get_env("username", envp);
+ const char *password = get_env("password", envp);
+
+ if (!context->test_deferred_auth)
+ {
+ plog(context, PLOG_NOTE, "Direct authentication");
+ return do_auth_user_pass(context, username, password) ?
+ OPENVPN_PLUGIN_FUNC_SUCCESS : OPENVPN_PLUGIN_FUNC_ERROR;
+ }
+
+ /* get auth_control_file filename from envp string array*/
+ const char *auth_control_file = get_env("auth_control_file", envp);
+ plog(context, PLOG_NOTE, "auth_control_file=%s", auth_control_file);
+
+ /* Authenticate asynchronously in n seconds */
+ if (!auth_control_file)
+ {
+ return OPENVPN_PLUGIN_FUNC_ERROR;
+ }
+
+ /* we do not want to complicate our lives with having to wait()
+ * for child processes (so they are not zombiefied) *and* we MUST NOT
+ * fiddle with signal handlers (= shared with openvpn main), so
+ * we use double-fork() trick.
+ */
+
+ /* fork, sleep, succeed (no "real" auth done = always succeed) */
+ pid_t p1 = fork();
+ if (p1 < 0) /* Fork failed */
+ {
+ return OPENVPN_PLUGIN_FUNC_ERROR;
+ }
+ if (p1 > 0) /* parent process */
+ {
+ waitpid(p1, NULL, 0);
+ return OPENVPN_PLUGIN_FUNC_DEFERRED;
+ }
+
+ /* first gen child process, fork() again and exit() right away */
+ pid_t p2 = fork();
+ if (p2 < 0)
+ {
+ plog(context, PLOG_ERR|PLOG_ERRNO, "BACKGROUND: fork(2) failed");
+ exit(1);
+ }
+
+ if (p2 != 0) /* new parent: exit right away */
+ {
+ exit(0);
+ }
+
+ /* (grand-)child process
+ * - never call "return" now (would mess up openvpn)
+ * - return status is communicated by file
+ * - then exit()
+ */
+
+ /* do mighty complicated work that will really take time here... */
+ plog(context, PLOG_NOTE, "in async/deferred handler, usleep(%d)",
+ context->test_deferred_auth*1000);
+ usleep(context->test_deferred_auth*1000);
+
+ /* now signal success state to openvpn */
+ int fd = open(auth_control_file, O_WRONLY);
+ if (fd < 0)
+ {
+ plog(context, PLOG_ERR|PLOG_ERRNO,
+ "open('%s') failed", auth_control_file);
+ exit(1);
+ }
+
+ char result[2] = "0\0";
+ if (do_auth_user_pass(context, username, password))
+ {
+ result[0] = '1';
+ }
+
+ if (write(fd, result, 1) != 1)
+ {
+ plog(context, PLOG_ERR|PLOG_ERRNO, "write to '%s' failed",
auth_control_file );
+ }
+ close(fd);
+
+ exit(0);
+}
+
+
+OPENVPN_EXPORT int
+openvpn_plugin_func_v3(const int v3structver,
+ struct openvpn_plugin_args_func_in const *args,
+ struct openvpn_plugin_args_func_return *ret)
+{
+ if (v3structver < OPENVPN_PLUGIN_STRUCTVER_MIN)
+ {
+ fprintf(stderr, "%s: this plugin is incompatible with the running
version of OpenVPN\n", MODULE);
+ return OPENVPN_PLUGIN_FUNC_ERROR;
+ }
+ const char **argv = args->argv;
+ const char **envp = args->envp;
+ struct plugin_context *context = (struct plugin_context *) args->handle;
+ struct plugin_per_client_context *pcc = (struct plugin_per_client_context
*) args->per_client_context;
+ switch (args->type)
+ {
+ case OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY:
+ plog(context, PLOG_NOTE, "OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY");
+ return auth_user_pass_verify(context, pcc, argv, envp);
+
+ default:
+ plog(context, PLOG_NOTE, "OPENVPN_PLUGIN_?");
+ return OPENVPN_PLUGIN_FUNC_ERROR;
+ }
+}
+
+OPENVPN_EXPORT void *
+openvpn_plugin_client_constructor_v1(openvpn_plugin_handle_t handle)
+{
+ struct plugin_context *context = (struct plugin_context *) handle;
+ plog(context, PLOG_NOTE, "FUNC: openvpn_plugin_client_constructor_v1");
+ return calloc(1, sizeof(struct plugin_per_client_context));
+}
+
+OPENVPN_EXPORT void
+openvpn_plugin_client_destructor_v1(openvpn_plugin_handle_t handle, void
*per_client_context)
+{
+ struct plugin_context *context = (struct plugin_context *) handle;
+ plog(context, PLOG_NOTE, "FUNC: openvpn_plugin_client_destructor_v1");
+ free(per_client_context);
+}
+
+OPENVPN_EXPORT void
+openvpn_plugin_close_v1(openvpn_plugin_handle_t handle)
+{
+ struct plugin_context *context = (struct plugin_context *) handle;
+ plog(context, PLOG_NOTE, "FUNC: openvpn_plugin_close_v1");
+ free(context);
+}
--
2.27.0
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