diff options
Diffstat (limited to 'sample/sample-plugins/defer/simple.c')
| -rw-r--r-- | sample/sample-plugins/defer/simple.c | 400 |
1 files changed, 301 insertions, 99 deletions
diff --git a/sample/sample-plugins/defer/simple.c b/sample/sample-plugins/defer/simple.c index d18695b..ba2e03e 100644 --- a/sample/sample-plugins/defer/simple.c +++ b/sample/sample-plugins/defer/simple.c @@ -5,7 +5,7 @@ * packet encryption, packet authentication, and * packet compression. * - * Copyright (C) 2002-2018 OpenVPN Inc <sales@openvpn.net> + * Copyright (C) 2002-2021 OpenVPN Inc <sales@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 @@ -54,13 +54,30 @@ #include <stdio.h> #include <string.h> #include <stdlib.h> +#include <unistd.h> +#include <stdbool.h> +#include <fcntl.h> +#include <sys/types.h> +#include <sys/wait.h> #include "openvpn-plugin.h" -/* bool definitions */ -#define bool int -#define true 1 -#define false 0 +/* Pointers to functions exported from openvpn */ +static plugin_log_t plugin_log = NULL; + +/* + * 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 /* * Our context, where we keep our state. @@ -76,6 +93,9 @@ struct plugin_per_client_context { bool generated_pf_file; }; +/* module name for plugin_log() */ +static char *MODULE = "defer/simple"; + /* * Given an environmental variable name, search * the envp array for its value, returning it @@ -130,28 +150,52 @@ atoi_null0(const char *str) } } -OPENVPN_EXPORT openvpn_plugin_handle_t -openvpn_plugin_open_v1(unsigned int *type_mask, const char *argv[], const char *envp[]) +/* 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) +{ + const char **envp = args->envp; /* environment variables */ struct plugin_context *context; - printf("FUNC: openvpn_plugin_open_v1\n"); + 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_log = args->callbacks->plugin_log; + + plugin_log(PLOG_NOTE, MODULE, "FUNC: openvpn_plugin_open_v3"); /* * Allocate our context */ context = (struct plugin_context *) calloc(1, sizeof(struct plugin_context)); + if (!context) + { + goto error; + } context->test_deferred_auth = atoi_null0(get_env("test_deferred_auth", envp)); - printf("TEST_DEFERRED_AUTH %d\n", context->test_deferred_auth); + plugin_log(PLOG_NOTE, MODULE, "TEST_DEFERRED_AUTH %d", context->test_deferred_auth); context->test_packet_filter = atoi_null0(get_env("test_packet_filter", envp)); - printf("TEST_PACKET_FILTER %d\n", context->test_packet_filter); + plugin_log(PLOG_NOTE, MODULE, "TEST_PACKET_FILTER %d", context->test_packet_filter); /* * Which callbacks to intercept. */ - *type_mask = + ret->type_mask = OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_UP) |OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_DOWN) |OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_ROUTE_UP) @@ -161,157 +205,315 @@ openvpn_plugin_open_v1(unsigned int *type_mask, const char *argv[], const char * |OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_CONNECT_V2) |OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_CLIENT_DISCONNECT) |OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_LEARN_ADDRESS) - |OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_TLS_FINAL) - |OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_ENABLE_PF); + |OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_TLS_FINAL); - return (openvpn_plugin_handle_t) context; + /* ENABLE_PF should only be called if we're actually willing to do PF */ + if (context->test_packet_filter) + { + ret->type_mask |= OPENVPN_PLUGIN_MASK(OPENVPN_PLUGIN_ENABLE_PF); + } + + ret->handle = (openvpn_plugin_handle_t *) context; + plugin_log(PLOG_NOTE, MODULE, "initialization succeeded"); + return OPENVPN_PLUGIN_FUNC_SUCCESS; + +error: + if (context) + { + free(context); + } + plugin_log(PLOG_NOTE, MODULE, "initialization failed"); + return OPENVPN_PLUGIN_FUNC_ERROR; } static int -auth_user_pass_verify(struct plugin_context *context, struct plugin_per_client_context *pcc, const char *argv[], const char *envp[]) +auth_user_pass_verify(struct plugin_context *context, + struct plugin_per_client_context *pcc, + const char *argv[], const char *envp[]) { - if (context->test_deferred_auth) + if (!context->test_deferred_auth) { - /* get username/password from envp string array */ - const char *username = get_env("username", envp); - const char *password = get_env("password", envp); + return OPENVPN_PLUGIN_FUNC_SUCCESS; + } + + /* get username/password from envp string array */ + const char *username = get_env("username", envp); + const char *password = get_env("password", envp); - /* get auth_control_file filename from envp string array*/ - const char *auth_control_file = get_env("auth_control_file", envp); + /* get auth_control_file filename from envp string array*/ + const char *auth_control_file = get_env("auth_control_file", envp); - printf("DEFER u='%s' p='%s' acf='%s'\n", + plugin_log(PLOG_NOTE, MODULE, "DEFER u='%s' p='%s' acf='%s'", np(username), np(password), np(auth_control_file)); - /* Authenticate asynchronously in n seconds */ - if (auth_control_file) - { - char buf[256]; - int auth = 2; - sscanf(username, "%d", &auth); - snprintf(buf, sizeof(buf), "( sleep %d ; echo AUTH %s %d ; echo %d >%s ) &", - context->test_deferred_auth, - auth_control_file, - auth, - pcc->n_calls < auth, - auth_control_file); - printf("%s\n", buf); - system(buf); - pcc->n_calls++; - return OPENVPN_PLUGIN_FUNC_DEFERRED; - } - else - { - return OPENVPN_PLUGIN_FUNC_ERROR; - } + /* Authenticate asynchronously in n seconds */ + if (!auth_control_file) + { + return OPENVPN_PLUGIN_FUNC_ERROR; } - else + + /* 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_SUCCESS; + 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) + { + plugin_log(PLOG_ERR|PLOG_ERRNO, MODULE, "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... */ + plugin_log(PLOG_NOTE, MODULE, "in async/deferred handler, sleep(%d)", context->test_deferred_auth); + sleep(context->test_deferred_auth); + + /* now signal success state to openvpn */ + int fd = open(auth_control_file, O_WRONLY); + if (fd < 0) + { + plugin_log(PLOG_ERR|PLOG_ERRNO, MODULE, "open('%s') failed", auth_control_file); + exit(1); } + + plugin_log(PLOG_NOTE, MODULE, "auth_user_pass_verify: done" ); + + if (write(fd, "1", 1) != 1) + { + plugin_log(PLOG_ERR|PLOG_ERRNO, MODULE, "write to '%s' failed", auth_control_file ); + } + close(fd); + + exit(0); } static int tls_final(struct plugin_context *context, struct plugin_per_client_context *pcc, const char *argv[], const char *envp[]) { - if (context->test_packet_filter) + if (!context->test_packet_filter) /* no PF testing, nothing to do */ { - if (!pcc->generated_pf_file) + return OPENVPN_PLUGIN_FUNC_SUCCESS; + } + + if (pcc->generated_pf_file) /* we already have created a file */ + { + return OPENVPN_PLUGIN_FUNC_ERROR; + } + + const char *pff = get_env("pf_file", envp); + const char *cn = get_env("username", envp); + if (!pff || !cn) /* required vars missing */ + { + return OPENVPN_PLUGIN_FUNC_ERROR; + } + + pcc->generated_pf_file = true; + + /* the PF API is, basically + * - OpenVPN sends a filename (pf_file) to the plugin + * - OpenVPN main loop will check every second if that file shows up + * - when it does, it will be read & used for the pf config + * the pre-created file needs to be removed in ...ENABLE_PF + * to make deferred PF setup work + * + * the regular PF hook does not know the client username or CN, so + * this is deferred to the TLS_FINAL hook which knows these things + */ + + /* do the double fork dance (see above for more verbose comments) + */ + 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_SUCCESS; /* no _DEFERRED here! */ + } + + /* first gen child process, fork() again and exit() right away */ + pid_t p2 = fork(); + if (p2 < 0) + { + plugin_log(PLOG_ERR|PLOG_ERRNO, MODULE, "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() + */ + + /* at this point, the plugin can take its time, because OpenVPN will + * no longer block waiting for the call to finish + * + * in this example, we build a PF file by copying over a file + * named "<username>.pf" to the OpenVPN-provided pf file name + * + * a real example could do a LDAP lookup, a REST call, ... + */ + plugin_log(PLOG_NOTE, MODULE, "in async/deferred tls_final handler, sleep(%d)", context->test_packet_filter); + sleep(context->test_packet_filter); + + char buf[256]; + snprintf(buf, sizeof(buf), "%s.pf", cn ); + + /* there is a small race condition here - OpenVPN could detect our + * file while we have only written half of it. So "perfect" code + * needs to create this with a temp file name, and then rename() it + * after it has been written. But I am lazy. + */ + + int w_fd = open( pff, O_WRONLY|O_CREAT, 0600 ); + if (w_fd < 0) + { + plugin_log(PLOG_ERR|PLOG_ERRNO, MODULE, "can't write to '%s'", pff); + exit(0); + } + + int r_fd = open( buf, O_RDONLY ); + if (r_fd < 0) + { + plugin_log(PLOG_ERR|PLOG_ERRNO, MODULE, "can't read '%s', creating empty pf file", buf); + close(w_fd); + exit(0); + } + + char data[1024]; + + int r; + do + { + r = read(r_fd, data, sizeof(data)); + if (r < 0) { - const char *pff = get_env("pf_file", envp); - const char *cn = get_env("username", envp); - if (pff && cn) - { - char buf[256]; - snprintf(buf, sizeof(buf), "( sleep %d ; echo PF %s/%s ; cp \"%s.pf\" \"%s\" ) &", - context->test_packet_filter, cn, pff, cn, pff); - printf("%s\n", buf); - system(buf); - pcc->generated_pf_file = true; - return OPENVPN_PLUGIN_FUNC_SUCCESS; - } - else - { - return OPENVPN_PLUGIN_FUNC_ERROR; - } + plugin_log(PLOG_ERR|PLOG_ERRNO, MODULE, "error reading '%s'", buf); + close(r_fd); + close(w_fd); + exit(0); } - else + int w = write(w_fd, data, r); + if (w < 0 || w != r) { - return OPENVPN_PLUGIN_FUNC_ERROR; + plugin_log(PLOG_ERR|PLOG_ERRNO, MODULE, "error writing %d bytes to '%s'", r, pff); + close(r_fd); + close(w_fd); + exit(0); } } - else - { - return OPENVPN_PLUGIN_FUNC_SUCCESS; - } + while(r > 0); + + plugin_log(PLOG_NOTE, MODULE, "copied PF config from '%s' to '%s', job done", buf, pff); + exit(0); } OPENVPN_EXPORT int -openvpn_plugin_func_v2(openvpn_plugin_handle_t handle, - const int type, - const char *argv[], - const char *envp[], - void *per_client_context, - struct openvpn_plugin_string_list **return_list) +openvpn_plugin_func_v3(const int v3structver, + struct openvpn_plugin_args_func_in const *args, + struct openvpn_plugin_args_func_return *ret) { - struct plugin_context *context = (struct plugin_context *) handle; - struct plugin_per_client_context *pcc = (struct plugin_per_client_context *) per_client_context; - switch (type) + 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_UP: - printf("OPENVPN_PLUGIN_UP\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_UP"); return OPENVPN_PLUGIN_FUNC_SUCCESS; case OPENVPN_PLUGIN_DOWN: - printf("OPENVPN_PLUGIN_DOWN\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_DOWN"); return OPENVPN_PLUGIN_FUNC_SUCCESS; case OPENVPN_PLUGIN_ROUTE_UP: - printf("OPENVPN_PLUGIN_ROUTE_UP\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_ROUTE_UP"); return OPENVPN_PLUGIN_FUNC_SUCCESS; case OPENVPN_PLUGIN_IPCHANGE: - printf("OPENVPN_PLUGIN_IPCHANGE\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_IPCHANGE"); return OPENVPN_PLUGIN_FUNC_SUCCESS; case OPENVPN_PLUGIN_TLS_VERIFY: - printf("OPENVPN_PLUGIN_TLS_VERIFY\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_TLS_VERIFY"); return OPENVPN_PLUGIN_FUNC_SUCCESS; case OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY: - printf("OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_AUTH_USER_PASS_VERIFY"); return auth_user_pass_verify(context, pcc, argv, envp); case OPENVPN_PLUGIN_CLIENT_CONNECT_V2: - printf("OPENVPN_PLUGIN_CLIENT_CONNECT_V2\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_CLIENT_CONNECT_V2"); return OPENVPN_PLUGIN_FUNC_SUCCESS; case OPENVPN_PLUGIN_CLIENT_DISCONNECT: - printf("OPENVPN_PLUGIN_CLIENT_DISCONNECT\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_CLIENT_DISCONNECT"); return OPENVPN_PLUGIN_FUNC_SUCCESS; case OPENVPN_PLUGIN_LEARN_ADDRESS: - printf("OPENVPN_PLUGIN_LEARN_ADDRESS\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_LEARN_ADDRESS"); return OPENVPN_PLUGIN_FUNC_SUCCESS; case OPENVPN_PLUGIN_TLS_FINAL: - printf("OPENVPN_PLUGIN_TLS_FINAL\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_TLS_FINAL"); return tls_final(context, pcc, argv, envp); case OPENVPN_PLUGIN_ENABLE_PF: - printf("OPENVPN_PLUGIN_ENABLE_PF\n"); - if (context->test_packet_filter) - { - return OPENVPN_PLUGIN_FUNC_SUCCESS; - } - else + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_ENABLE_PF"); + + /* OpenVPN pre-creates the file, which gets in the way of + * deferred pf setup - so remove it here, and re-create + * it in the background handler (in tls_final()) when ready + */ + const char *pff = get_env("pf_file", envp); + if (pff) { - return OPENVPN_PLUGIN_FUNC_ERROR; + (void) unlink(pff); } + return OPENVPN_PLUGIN_FUNC_SUCCESS; /* must succeed */ default: - printf("OPENVPN_PLUGIN_?\n"); + plugin_log(PLOG_NOTE, MODULE, "OPENVPN_PLUGIN_?"); return OPENVPN_PLUGIN_FUNC_ERROR; } } @@ -319,14 +521,14 @@ openvpn_plugin_func_v2(openvpn_plugin_handle_t handle, OPENVPN_EXPORT void * openvpn_plugin_client_constructor_v1(openvpn_plugin_handle_t handle) { - printf("FUNC: openvpn_plugin_client_constructor_v1\n"); + plugin_log(PLOG_NOTE, MODULE, "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) { - printf("FUNC: openvpn_plugin_client_destructor_v1\n"); + plugin_log(PLOG_NOTE, MODULE, "FUNC: openvpn_plugin_client_destructor_v1"); free(per_client_context); } @@ -334,6 +536,6 @@ OPENVPN_EXPORT void openvpn_plugin_close_v1(openvpn_plugin_handle_t handle) { struct plugin_context *context = (struct plugin_context *) handle; - printf("FUNC: openvpn_plugin_close_v1\n"); + plugin_log(PLOG_NOTE, MODULE, "FUNC: openvpn_plugin_close_v1"); free(context); } |