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/* -*- coding: utf-8 -*- */
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* Mandos plugin runner - Run Mandos plugins
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* Copyright © 2007-2008 Teddy Hogeborn & Björn Påhlsson
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* This program is free software: you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see
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* <http://www.gnu.org/licenses/>.
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* Contact the authors at <mandos@fukt.bsnet.se>.
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#define _GNU_SOURCE /* TEMP_FAILURE_RETRY(), getline(),
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#include <stddef.h> /* size_t, NULL */
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#include <stdlib.h> /* malloc(), exit(), EXIT_FAILURE,
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EXIT_SUCCESS, realloc() */
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#include <stdbool.h> /* bool, true, false */
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#include <stdio.h> /* perror, popen(), fileno(),
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fprintf(), stderr, STDOUT_FILENO */
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#include <sys/types.h> /* DIR, opendir(), stat(), struct
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stat, waitpid(), WIFEXITED(),
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WEXITSTATUS(), wait(), pid_t,
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uid_t, gid_t, getuid(), getgid(),
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#include <sys/select.h> /* fd_set, select(), FD_ZERO(),
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FD_SET(), FD_ISSET(), FD_CLR */
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#include <sys/wait.h> /* wait(), waitpid(), WIFEXITED(),
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#include <sys/stat.h> /* struct stat, stat(), S_ISREG() */
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#include <iso646.h> /* and, or, not */
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#include <dirent.h> /* DIR, struct dirent, opendir(),
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readdir(), closedir(), dirfd() */
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#include <unistd.h> /* struct stat, stat(), S_ISREG(),
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fcntl(), setuid(), setgid(),
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F_GETFD, F_SETFD, FD_CLOEXEC,
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access(), pipe(), fork(), close()
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dup2, STDOUT_FILENO, _exit(),
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execv(), write(), read(),
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#include <fcntl.h> /* fcntl(), F_GETFD, F_SETFD,
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#include <string.h> /* strsep, strlen(), asprintf() */
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#include <errno.h> /* errno */
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#include <argp.h> /* struct argp_option, struct
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argp_state, struct argp,
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argp_parse(), ARGP_ERR_UNKNOWN,
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ARGP_KEY_END, ARGP_KEY_ARG,
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#include <signal.h> /* struct sigaction, sigemptyset(),
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sigaddset(), sigaction(),
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sigprocmask(), SIG_BLOCK, SIGCHLD,
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SIG_UNBLOCK, kill() */
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#include <errno.h> /* errno, EBADF */
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#define BUFFER_SIZE 256
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#define ARGFILE "/conf/conf.d/mandos/plugin-runner.conf"
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const char *argp_program_version = "plugin-runner 1.0";
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const char *argp_program_bug_address = "<mandos@fukt.bsnet.se>";
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typedef struct process{
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volatile bool completed;
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typedef struct plugin{
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char *name; /* can be NULL or any plugin name */
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static plugin *getplugin(char *name, plugin **plugin_list){
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for (plugin *p = *plugin_list; p != NULL; p = p->next){
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or (p->name and name and (strcmp(p->name, name) == 0))){
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/* Create a new plugin */
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plugin *new_plugin = malloc(sizeof(plugin));
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if (new_plugin == NULL){
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char *copy_name = NULL;
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copy_name = strdup(name);
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if(copy_name == NULL){
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*new_plugin = (plugin) { .name = copy_name,
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.next = *plugin_list };
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new_plugin->argv = malloc(sizeof(char *) * 2);
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if (new_plugin->argv == NULL){
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new_plugin->argv[0] = copy_name;
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new_plugin->argv[1] = NULL;
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new_plugin->environ = malloc(sizeof(char *));
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if(new_plugin->environ == NULL){
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free(new_plugin->argv);
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new_plugin->environ[0] = NULL;
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/* Append the new plugin to the list */
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*plugin_list = new_plugin;
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/* Helper function for add_argument and add_environment */
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static bool add_to_char_array(const char *new, char ***array,
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/* Resize the pointed-to array to hold one more pointer */
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*array = realloc(*array, sizeof(char *)
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* (size_t) ((*len) + 2));
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/* Make a copy of the new string */
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char *copy = strdup(new);
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/* Insert the copy */
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(*array)[*len] = copy;
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/* Add a new terminating NULL pointer to the last element */
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(*array)[*len] = NULL;
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/* Add to a plugin's argument vector */
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static bool add_argument(plugin *p, const char *arg){
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return add_to_char_array(arg, &(p->argv), &(p->argc));
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/* Add to a plugin's environment */
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static bool add_environment(plugin *p, const char *def){
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return add_to_char_array(def, &(p->environ), &(p->envc));
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* Based on the example in the GNU LibC manual chapter 13.13 "File
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* *Note File Descriptor Flags:(libc)Descriptor Flags.
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static int set_cloexec_flag(int fd)
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int ret = fcntl(fd, F_GETFD, 0);
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/* If reading the flags failed, return error indication now. */
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/* Store modified flag word in the descriptor. */
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return fcntl(fd, F_SETFD, ret | FD_CLOEXEC);
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process *process_list = NULL;
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/* Mark processes as completed when they exit, and save their exit
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void handle_sigchld(__attribute__((unused)) int sig){
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process *proc = process_list;
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pid_t pid = waitpid(-1, &status, WNOHANG);
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/* Only still running child processes */
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if (errno != ECHILD){
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/* No child processes */
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/* A child exited, find it in process_list */
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while(proc != NULL and proc->pid != pid){
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/* Process not found in process list */
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proc->status = status;
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proc->completed = true;
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bool print_out_password(const char *buffer, size_t length){
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if(length>0 and buffer[length-1] == '\n'){
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for(size_t written = 0; written < length; written += (size_t)ret){
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ret = TEMP_FAILURE_RETRY(write(STDOUT_FILENO, buffer + written,
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char **add_to_argv(char **argv, int *argc, char *arg){
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argv = malloc(sizeof(char*) * 2);
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argv[0] = NULL; /* Will be set to argv[0] in main before
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argv = realloc(argv, sizeof(char *)
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* ((unsigned int) *argc + 1));
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static void free_plugin_list(plugin *plugin_list){
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for(plugin *next; plugin_list != NULL; plugin_list = next){
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next = plugin_list->next;
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for(char **arg = plugin_list->argv; *arg != NULL; arg++){
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free(plugin_list->argv);
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for(char **env = plugin_list->environ; *env != NULL; env++){
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free(plugin_list->environ);
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int main(int argc, char *argv[]){
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const char *plugindir = "/lib/mandos/plugins.d";
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const char *argfile = ARGFILE;
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struct dirent *dirst;
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int exitstatus = EXIT_SUCCESS;
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struct sigaction old_sigchld_action;
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struct sigaction sigchld_action = { .sa_handler = handle_sigchld,
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.sa_flags = SA_NOCLDSTOP };
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char **custom_argv = NULL;
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/* Establish a signal handler */
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sigemptyset(&sigchld_action.sa_mask);
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ret = sigaddset(&sigchld_action.sa_mask, SIGCHLD);
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exitstatus = EXIT_FAILURE;
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ret = sigaction(SIGCHLD, &sigchld_action, &old_sigchld_action);
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exitstatus = EXIT_FAILURE;
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/* The options we understand. */
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struct argp_option options[] = {
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{ .name = "global-options", .key = 'g',
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.arg = "OPTION[,OPTION[,...]]",
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.doc = "Options passed to all plugins" },
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{ .name = "global-envs", .key = 'e',
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.doc = "Environment variable passed to all plugins" },
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{ .name = "options-for", .key = 'o',
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.arg = "PLUGIN:OPTION[,OPTION[,...]]",
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.doc = "Options passed only to specified plugin" },
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{ .name = "envs-for", .key = 'f',
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.arg = "PLUGIN:ENV=value",
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.doc = "Environment variable passed to specified plugin" },
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{ .name = "disable", .key = 'd',
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.doc = "Disable a specific plugin", .group = 1 },
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{ .name = "plugin-dir", .key = 128,
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.doc = "Specify a different plugin directory", .group = 2 },
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{ .name = "userid", .key = 129,
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.arg = "ID", .flags = 0,
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.doc = "User ID the plugins will run as", .group = 2 },
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{ .name = "groupid", .key = 130,
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.arg = "ID", .flags = 0,
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.doc = "Group ID the plugins will run as", .group = 2 },
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{ .name = "debug", .key = 131,
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.doc = "Debug mode", .group = 3 },
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error_t parse_opt (int key, char *arg, struct argp_state *state) {
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/* Get the INPUT argument from `argp_parse', which we know is a
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pointer to our plugin list pointer. */
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plugin **plugins = state->input;
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while((p = strsep(&arg, ",")) != NULL){
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if(not add_argument(getplugin(NULL, plugins), p)){
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perror("add_argument");
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return ARGP_ERR_UNKNOWN;
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char *envdef = strdup(arg);
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if(not add_environment(getplugin(NULL, plugins), envdef)){
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perror("add_environment");
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char *p_name = strsep(&arg, ":");
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if(p_name[0] == '\0'){
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char *opt = strsep(&arg, ":");
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while((p = strsep(&opt, ",")) != NULL){
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if(not add_argument(getplugin(p_name, plugins), p)){
403
perror("add_argument");
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return ARGP_ERR_UNKNOWN;
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char *envdef = strchr(arg, ':');
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char *p_name = strndup(arg, (size_t) (envdef-arg));
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if(not add_environment(getplugin(p_name, plugins), envdef)){
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perror("add_environment");
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plugin *p = getplugin(arg, plugins);
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return ARGP_ERR_UNKNOWN;
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uid = (uid_t)strtol(arg, NULL, 10);
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gid = (gid_t)strtol(arg, NULL, 10);
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fprintf(stderr, "Ignoring unknown argument \"%s\"\n", arg);
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return ARGP_ERR_UNKNOWN;
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plugin *plugin_list = NULL;
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struct argp argp = { .options = options, .parser = parse_opt,
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.args_doc = "[+PLUS_SEPARATED_OPTIONS]",
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.doc = "Mandos plugin runner -- Run plugins" };
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ret = argp_parse (&argp, argc, argv, 0, 0, &plugin_list);
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if (ret == ARGP_ERR_UNKNOWN){
469
fprintf(stderr, "Unknown error while parsing arguments\n");
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exitstatus = EXIT_FAILURE;
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conffp = fopen(argfile, "r");
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char *org_line = NULL;
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char *p, *arg, *new_arg, *line;
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const char whitespace_delims[] = " \r\t\f\v\n";
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const char comment_delim[] = "#";
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sret = getline(&org_line, &size, conffp);
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arg = strsep(&line, comment_delim);
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while((p = strsep(&arg, whitespace_delims)) != NULL){
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custom_argv = add_to_argv(custom_argv, &custom_argc, new_arg);
497
if (custom_argv == NULL){
498
perror("add_to_argv");
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exitstatus = EXIT_FAILURE;
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/* Check for harmful errors and go to fallback. Other errors might
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not affect opening plugins */
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if (errno == EMFILE or errno == ENFILE or errno == ENOMEM){
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exitstatus = EXIT_FAILURE;
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if(custom_argv != NULL){
516
custom_argv[0] = argv[0];
517
ret = argp_parse (&argp, custom_argc, custom_argv, 0, 0,
519
if (ret == ARGP_ERR_UNKNOWN){
520
fprintf(stderr, "Unknown error while parsing arguments\n");
521
exitstatus = EXIT_FAILURE;
527
for(plugin *p = plugin_list; p != NULL; p=p->next){
528
fprintf(stderr, "Plugin: %s has %d arguments\n",
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p->name ? p->name : "Global", p->argc - 1);
530
for(char **a = p->argv; *a != NULL; a++){
531
fprintf(stderr, "\tArg: %s\n", *a);
533
fprintf(stderr, "...and %u environment variables\n", p->envc);
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for(char **a = p->environ; *a != NULL; a++){
535
fprintf(stderr, "\t%s\n", *a);
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dir = opendir(plugindir);
552
perror("Could not open plugin dir");
553
exitstatus = EXIT_FAILURE;
557
/* Set the FD_CLOEXEC flag on the directory, if possible */
559
int dir_fd = dirfd(dir);
561
ret = set_cloexec_flag(dir_fd);
563
perror("set_cloexec_flag");
564
exitstatus = EXIT_FAILURE;
573
dirst = readdir(dir);
575
// All directory entries have been processed
579
exitstatus = EXIT_FAILURE;
585
d_name_len = strlen(dirst->d_name);
587
// Ignore dotfiles, backup files and other junk
589
bool bad_name = false;
591
const char const *bad_prefixes[] = { ".", "#", NULL };
593
const char const *bad_suffixes[] = { "~", "#", ".dpkg-new",
595
".dpkg-divert", NULL };
596
for(const char **pre = bad_prefixes; *pre != NULL; pre++){
597
size_t pre_len = strlen(*pre);
598
if((d_name_len >= pre_len)
599
and strncmp((dirst->d_name), *pre, pre_len) == 0){
601
fprintf(stderr, "Ignoring plugin dir entry \"%s\""
602
" with bad prefix %s\n", dirst->d_name, *pre);
613
for(const char **suf = bad_suffixes; *suf != NULL; suf++){
614
size_t suf_len = strlen(*suf);
615
if((d_name_len >= suf_len)
616
and (strcmp((dirst->d_name)+d_name_len-suf_len, *suf)
619
fprintf(stderr, "Ignoring plugin dir entry \"%s\""
620
" with bad suffix %s\n", dirst->d_name, *suf);
633
ret = asprintf(&filename, "%s/%s", plugindir, dirst->d_name);
639
ret = stat(filename, &st);
646
if (not S_ISREG(st.st_mode) or (access(filename, X_OK) != 0)){
648
fprintf(stderr, "Ignoring plugin dir entry \"%s\""
649
" with bad type or mode\n", filename);
654
plugin *p = getplugin(dirst->d_name, &plugin_list);
662
fprintf(stderr, "Ignoring disabled plugin \"%s\"\n",
669
/* Add global arguments to argument list for this plugin */
670
plugin *g = getplugin(NULL, &plugin_list);
672
for(char **a = g->argv + 1; *a != NULL; a++){
673
if(not add_argument(p, *a)){
674
perror("add_argument");
677
/* Add global environment variables */
678
for(char **e = g->environ; *e != NULL; e++){
679
if(not add_environment(p, *e)){
680
perror("add_environment");
685
/* If this plugin has any environment variables, we will call
686
using execve and need to duplicate the environment from this
688
if(p->environ[0] != NULL){
689
for(char **e = environ; *e != NULL; e++){
690
char *copy = strdup(*e);
695
if(not add_environment(p, copy)){
696
perror("add_environment");
705
exitstatus = EXIT_FAILURE;
708
ret = set_cloexec_flag(pipefd[0]);
710
perror("set_cloexec_flag");
711
exitstatus = EXIT_FAILURE;
714
ret = set_cloexec_flag(pipefd[1]);
716
perror("set_cloexec_flag");
717
exitstatus = EXIT_FAILURE;
720
/* Block SIGCHLD until process is safely in process list */
721
ret = sigprocmask (SIG_BLOCK, &sigchld_action.sa_mask, NULL);
723
perror("sigprocmask");
724
exitstatus = EXIT_FAILURE;
727
// Starting a new process to be watched
731
exitstatus = EXIT_FAILURE;
735
/* this is the child process */
736
ret = sigaction(SIGCHLD, &old_sigchld_action, NULL);
741
ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask, NULL);
743
perror("sigprocmask");
747
ret = dup2(pipefd[1], STDOUT_FILENO); /* replace our stdout */
754
/* If dir has no file descriptor, we could not set FD_CLOEXEC
755
above and must now close it manually here. */
758
if(p->environ[0] == NULL){
759
if(execv(filename, p->argv) < 0){
764
if(execve(filename, p->argv, p->environ) < 0){
773
close(pipefd[1]); /* close unused write end of pipe */
774
process *new_process = malloc(sizeof(process));
775
if (new_process == NULL){
777
ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask, NULL);
779
perror("sigprocmask");
781
exitstatus = EXIT_FAILURE;
785
*new_process = (struct process){ .pid = pid,
787
.next = process_list };
789
process_list = new_process;
790
/* Unblock SIGCHLD so signal handler can be run if this process
791
has already completed */
792
ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask, NULL);
794
perror("sigprocmask");
795
exitstatus = EXIT_FAILURE;
799
FD_SET(new_process->fd, &rfds_all);
801
if (maxfd < new_process->fd){
802
maxfd = new_process->fd;
807
free_plugin_list(plugin_list);
813
if (process_list == NULL){
814
fprintf(stderr, "No plugin processes started. Incorrect plugin"
819
fd_set rfds = rfds_all;
820
int select_ret = select(maxfd+1, &rfds, NULL, NULL, NULL);
821
if (select_ret == -1){
823
exitstatus = EXIT_FAILURE;
826
/* OK, now either a process completed, or something can be read
828
for(process *proc = process_list; proc ; proc = proc->next){
829
/* Is this process completely done? */
830
if(proc->eof and proc->completed){
831
/* Only accept the plugin output if it exited cleanly */
832
if(not WIFEXITED(proc->status)
833
or WEXITSTATUS(proc->status) != 0){
834
/* Bad exit by plugin */
836
if(WIFEXITED(proc->status)){
837
fprintf(stderr, "Plugin %u exited with status %d\n",
838
(unsigned int) (proc->pid),
839
WEXITSTATUS(proc->status));
840
} else if(WIFSIGNALED(proc->status)) {
841
fprintf(stderr, "Plugin %u killed by signal %d\n",
842
(unsigned int) (proc->pid),
843
WTERMSIG(proc->status));
844
} else if(WCOREDUMP(proc->status)){
845
fprintf(stderr, "Plugin %d dumped core\n",
846
(unsigned int) (proc->pid));
849
/* Remove the plugin */
850
FD_CLR(proc->fd, &rfds_all);
851
/* Block signal while modifying process_list */
852
ret = sigprocmask(SIG_BLOCK, &sigchld_action.sa_mask, NULL);
854
perror("sigprocmask");
855
exitstatus = EXIT_FAILURE;
858
/* Delete this process entry from the list */
859
if(process_list == proc){
860
/* First one - simple */
861
process_list = proc->next;
863
/* Second one or later */
864
for(process *p = process_list; p != NULL; p = p->next){
866
p->next = proc->next;
871
/* We are done modifying process list, so unblock signal */
872
ret = sigprocmask (SIG_UNBLOCK, &sigchld_action.sa_mask,
875
perror("sigprocmask");
879
/* We deleted this process from the list, so we can't go
880
proc->next. Therefore, start over from the beginning of
884
/* This process exited nicely, so print its buffer */
886
bool bret = print_out_password(proc->buffer,
887
proc->buffer_length);
889
perror("print_out_password");
890
exitstatus = EXIT_FAILURE;
894
/* This process has not completed. Does it have any output? */
895
if(proc->eof or not FD_ISSET(proc->fd, &rfds)){
896
/* This process had nothing to say at this time */
899
/* Before reading, make the process' data buffer large enough */
900
if(proc->buffer_length + BUFFER_SIZE > proc->buffer_size){
901
proc->buffer = realloc(proc->buffer, proc->buffer_size
902
+ (size_t) BUFFER_SIZE);
903
if (proc->buffer == NULL){
905
exitstatus = EXIT_FAILURE;
908
proc->buffer_size += BUFFER_SIZE;
910
/* Read from the process */
911
ret = read(proc->fd, proc->buffer + proc->buffer_length,
914
/* Read error from this process; ignore the error */
921
proc->buffer_length += (size_t) ret;
929
if(process_list == NULL or exitstatus != EXIT_SUCCESS){
930
/* Fallback if all plugins failed, none are found or an error
933
fprintf(stderr, "Going to fallback mode using getpass(3)\n");
934
char *passwordbuffer = getpass("Password: ");
935
bret = print_out_password(passwordbuffer, strlen(passwordbuffer));
937
perror("print_out_password");
938
exitstatus = EXIT_FAILURE;
942
/* Restore old signal handler */
943
ret = sigaction(SIGCHLD, &old_sigchld_action, NULL);
946
exitstatus = EXIT_FAILURE;
949
if(custom_argv != NULL){
950
for(char **arg = custom_argv; *arg != NULL; arg++){
955
free_plugin_list(plugin_list);
961
/* Free the process list and kill the processes */
962
for(process *next; process_list != NULL; process_list = next){
963
next = process_list->next;
964
close(process_list->fd);
965
ret = kill(process_list->pid, SIGTERM);
966
if(ret == -1 and errno != ESRCH){
967
/* set-uid proccesses migth not get closed */
970
free(process_list->buffer);
974
/* Wait for any remaining child processes to terminate */