/mandos/trunk

/*  -*- coding: utf-8 -*- */

/*

 * Mandos plugin runner - Run Mandos plugins

 *

 * Copyright © 2007-2008 Teddy Hogeborn & Björn Påhlsson

 * 

 * 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 3 of the

 * License, or (at your option) any later version.

 * 

 * 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, see

 * <http://www.gnu.org/licenses/>.

 * 

 * Contact the authors at <mandos@fukt.bsnet.se>.

 */

#define _GNU_SOURCE		/* TEMP_FAILURE_RETRY(), getline(),

				   asprintf() */

#include <stddef.h>		/* size_t, NULL */

#include <stdlib.h>		/* malloc(), exit(), EXIT_FAILURE,

				   EXIT_SUCCESS, realloc() */

#include <stdbool.h>		/* bool, true, false */

#include <stdio.h>		/* perror, popen(), fileno(),

				   fprintf(), stderr, STDOUT_FILENO */

#include <sys/types.h>	        /* DIR, opendir(), stat(), struct

				   stat, waitpid(), WIFEXITED(),

				   WEXITSTATUS(), wait(), pid_t,

				   uid_t, gid_t, getuid(), getgid(),

				   dirfd() */

#include <sys/select.h>		/* fd_set, select(), FD_ZERO(),

				   FD_SET(), FD_ISSET(), FD_CLR */

#include <sys/wait.h>		/* wait(), waitpid(), WIFEXITED(),

				   WEXITSTATUS() */

#include <sys/stat.h>		/* struct stat, stat(), S_ISREG() */

#include <iso646.h>		/* and, or, not */

#include <dirent.h>		/* DIR, struct dirent, opendir(),

				   readdir(), closedir(), dirfd() */

#include <unistd.h>		/* struct stat, stat(), S_ISREG(),

				   fcntl(), setuid(), setgid(),

				   F_GETFD, F_SETFD, FD_CLOEXEC,

				   access(), pipe(), fork(), close()

				   dup2, STDOUT_FILENO, _exit(),

				   execv(), write(), read(),

				   close() */

#include <fcntl.h>		/* fcntl(), F_GETFD, F_SETFD,

				   FD_CLOEXEC */

#include <string.h>		/* strsep, strlen(), asprintf() */

#include <errno.h>		/* errno */

#include <argp.h>		/* struct argp_option, struct

				   argp_state, struct argp,

				   argp_parse(), ARGP_ERR_UNKNOWN,

				   ARGP_KEY_END, ARGP_KEY_ARG, error_t */

#include <signal.h> 		/* struct sigaction, sigemptyset(),

				   sigaddset(), sigaction(),

				   sigprocmask(), SIG_BLOCK, SIGCHLD,

				   SIG_UNBLOCK, kill() */

#include <errno.h>		/* errno, EBADF */

#define BUFFER_SIZE 256

#define ARGFILE "/conf/conf.d/mandos/plugin-runner.conf"

const char *argp_program_version = "plugin-runner 1.0";

const char *argp_program_bug_address = "<mandos@fukt.bsnet.se>";

struct process;

typedef struct process{

  pid_t pid;

  int fd;

  char *buffer;

  size_t buffer_size;

  size_t buffer_length;

  bool eof;

  bool completed;

  int status;

  struct process *next;

} process;

typedef struct plugin{

  char *name;			/* can be NULL or any plugin name */

  char **argv;

  int argc;

  char **environ;

  int envc;

  bool disabled;

  struct plugin *next;

} plugin;

static plugin *getplugin(char *name, plugin **plugin_list){

  for (plugin *p = *plugin_list; p != NULL; p = p->next){

    if ((p->name == name)

	or (p->name and name and (strcmp(p->name, name) == 0))){

      return p;

    }

  }

  /* Create a new plugin */

  plugin *new_plugin = malloc(sizeof(plugin));

  if (new_plugin == NULL){

    return NULL;

  }

  *new_plugin = (plugin) { .name = name,

			   .argc = 1,

			   .envc = 0,

			   .disabled = false,

			   .next = *plugin_list };

  new_plugin->argv = malloc(sizeof(char *) * 2);

  if (new_plugin->argv == NULL){

    free(new_plugin);

    return NULL;

  }

  new_plugin->argv[0] = name;

  new_plugin->argv[1] = NULL;

  new_plugin->environ = malloc(sizeof(char *));

  if(new_plugin->environ == NULL){

    free(new_plugin->argv);

    free(new_plugin);

    return NULL;

  }

  new_plugin->environ[0] = NULL;

  /* Append the new plugin to the list */

  *plugin_list = new_plugin;

  return new_plugin;

}

/* Helper function for add_argument and add_environment */

static bool add_to_char_array(const char *new, char ***array,

			      int *len){

  /* Resize the pointed-to array to hold one more pointer */

  *array = realloc(*array, sizeof(char *)

		   * (size_t) ((*len) + 2));

  /* Malloc check */

  if(*array == NULL){

    return false;

  }

  /* Make a copy of the new string */

  char *copy = strdup(new);

  if(copy == NULL){

    return false;

  }

  /* Insert the copy */

  (*array)[*len] = copy;

  (*len)++;

  /* Add a new terminating NULL pointer to the last element */

  (*array)[*len] = NULL;

  return true;

}

/* Add to a plugin's argument vector */

static bool add_argument(plugin *p, const char *arg){

  if(p == NULL){

    return false;

  }

  return add_to_char_array(arg, &(p->argv), &(p->argc));

}

/* Add to a plugin's environment */

static bool add_environment(plugin *p, const char *def){

  if(p == NULL){

    return false;

  }

  return add_to_char_array(def, &(p->environ), &(p->envc));

}

/*

 * Based on the example in the GNU LibC manual chapter 13.13 "File

 * Descriptor Flags".

 * *Note File Descriptor Flags:(libc)Descriptor Flags.

 */

static int set_cloexec_flag(int fd)

{

  int ret = fcntl(fd, F_GETFD, 0);

  /* If reading the flags failed, return error indication now. */

  if(ret < 0){

    return ret;

  }

  /* Store modified flag word in the descriptor. */

  return fcntl(fd, F_SETFD, ret | FD_CLOEXEC);

}

process *process_list = NULL;

/* Mark a process as completed when it exits, and save its exit

   status. */

void handle_sigchld(__attribute__((unused)) int sig){

  process *proc = process_list;

  int status;

  pid_t pid = wait(&status);

  if(pid == -1){

    perror("wait");

    return;

  }

  while(proc != NULL and proc->pid != pid){

    proc = proc->next;

  }

  if(proc == NULL){

    /* Process not found in process list */

    return;

  }

  proc->status = status;

  proc->completed = true;

}

bool print_out_password(const char *buffer, size_t length){

  ssize_t ret;

  if(length>0 and buffer[length-1] == '\n'){

    length--;

  }

  for(size_t written = 0; written < length; written += (size_t)ret){

    ret = TEMP_FAILURE_RETRY(write(STDOUT_FILENO, buffer + written,

				   length - written));

    if(ret < 0){

      return false;

    }

  }

  return true;

}

char **add_to_argv(char **argv, int *argc, char *arg){

  if (argv == NULL){

    *argc = 1;

    argv = malloc(sizeof(char*) * 2);

    if(argv == NULL){

      return NULL;

    }

    argv[0] = NULL; 	/* Will be set to argv[0] in main before parsing */

    argv[1] = NULL;

  }

  *argc += 1;

  argv = realloc(argv, sizeof(char *)

		  * ((unsigned int) *argc + 1));

  if(argv == NULL){

    return NULL;

  }

  argv[*argc-1] = arg;

  argv[*argc] = NULL;   

  return argv;

}

int main(int argc, char *argv[]){

  const char *plugindir = "/lib/mandos/plugins.d";

  const char *argfile = ARGFILE;

  FILE *conffp;

  size_t d_name_len;

  DIR *dir = NULL;

  struct dirent *dirst;

  struct stat st;

  fd_set rfds_all;

  int ret, maxfd = 0;

  uid_t uid = 65534;

  gid_t gid = 65534;

  bool debug = false;

  int exitstatus = EXIT_SUCCESS;

  struct sigaction old_sigchld_action;

  struct sigaction sigchld_action = { .sa_handler = handle_sigchld,

				      .sa_flags = SA_NOCLDSTOP };

  char **custom_argv = NULL;

  int custom_argc = 0;

  /* Establish a signal handler */

  sigemptyset(&sigchld_action.sa_mask);

  ret = sigaddset(&sigchld_action.sa_mask, SIGCHLD);

  if(ret < 0){

    perror("sigaddset");

    exit(EXIT_FAILURE);

  }

  ret = sigaction(SIGCHLD, &sigchld_action, &old_sigchld_action);

  if(ret < 0){

    perror("sigaction");

    exit(EXIT_FAILURE);

  }

  /* The options we understand. */

  struct argp_option options[] = {

    { .name = "global-options", .key = 'g',

      .arg = "OPTION[,OPTION[,...]]",

      .doc = "Options passed to all plugins" },

    { .name = "global-envs", .key = 'e',

      .arg = "VAR=value",

      .doc = "Environment variable passed to all plugins" },

    { .name = "options-for", .key = 'o',

      .arg = "PLUGIN:OPTION[,OPTION[,...]]",

      .doc = "Options passed only to specified plugin" },

    { .name = "envs-for", .key = 'f',

      .arg = "PLUGIN:ENV=value",

      .doc = "Environment variable passed to specified plugin" },

    { .name = "disable", .key = 'd',

      .arg = "PLUGIN",

      .doc = "Disable a specific plugin", .group = 1 },

    { .name = "plugin-dir", .key = 128,

      .arg = "DIRECTORY",

      .doc = "Specify a different plugin directory", .group = 2 },

    { .name = "userid", .key = 129,

      .arg = "ID", .flags = 0,

      .doc = "User ID the plugins will run as", .group = 2 },

    { .name = "groupid", .key = 130,

      .arg = "ID", .flags = 0,

      .doc = "Group ID the plugins will run as", .group = 2 },

    { .name = "debug", .key = 131,

      .doc = "Debug mode", .group = 3 },

    { .name = NULL }

  };

  error_t parse_opt (int key, char *arg, struct argp_state *state) {

    /* Get the INPUT argument from `argp_parse', which we know is a

       pointer to our plugin list pointer. */

    plugin **plugins = state->input;

    switch (key) {

    case 'g':

      if (arg != NULL){

	char *p;

	while((p = strsep(&arg, ",")) != NULL){

	  if(p[0] == '\0'){

	    continue;

	  }

	  if(not add_argument(getplugin(NULL, plugins), p)){

	    perror("add_argument");

	    return ARGP_ERR_UNKNOWN;

	  }

	}

      }

      break;

    case 'e':

      if(arg == NULL){

	break;

      }

      {

	char *envdef = strdup(arg);

	if(envdef == NULL){

	  break;

	}

	if(not add_environment(getplugin(NULL, plugins), envdef)){

	  perror("add_environment");

	}

      }

      break;

    case 'o':

      if (arg != NULL){

	char *p_name = strsep(&arg, ":");

	if(p_name[0] == '\0'){

	  break;

	}

	char *opt = strsep(&arg, ":");

	if(opt[0] == '\0'){

	  break;

	}

	if(opt != NULL){

	  char *p;

	  while((p = strsep(&opt, ",")) != NULL){

	    if(p[0] == '\0'){

	      continue;

	    }

	    if(not add_argument(getplugin(p_name, plugins), p)){

	      perror("add_argument");

	      return ARGP_ERR_UNKNOWN;

	    }

	  }

	}

      }

      break;

    case 'f':

      if(arg == NULL){

	break;

      }

      {

	char *envdef = strchr(arg, ':');

	if(envdef == NULL){

	  break;

	}

	char *p_name = strndup(arg, (size_t) (envdef-arg));

	if(p_name == NULL){

	  break;

	}

	envdef++;

	if(not add_environment(getplugin(p_name, plugins), envdef)){

	  perror("add_environment");

	}

      }

      break;

    case 'd':

      if (arg != NULL){

	plugin *p = getplugin(arg, plugins);

	if(p == NULL){

	  return ARGP_ERR_UNKNOWN;

	}

	p->disabled = true;

      }

      break;

    case 128:

      plugindir = arg;

      break;

    case 129:

      uid = (uid_t)strtol(arg, NULL, 10);

      break;

    case 130:

      gid = (gid_t)strtol(arg, NULL, 10);

      break;

    case 131:

      debug = true;

      break;

    case ARGP_KEY_ARG:

      fprintf(stderr, "Ignoring unknown argument \"%s\"\n", arg);

      break;

    case ARGP_KEY_END:

      break;

    default:

      return ARGP_ERR_UNKNOWN;

    }

    return 0;

  }

  plugin *plugin_list = NULL;

  struct argp argp = { .options = options, .parser = parse_opt,

		       .args_doc = "[+PLUS_SEPARATED_OPTIONS]",

		       .doc = "Mandos plugin runner -- Run plugins" };

  ret = argp_parse (&argp, argc, argv, 0, 0, &plugin_list);

  if (ret == ARGP_ERR_UNKNOWN){

    fprintf(stderr, "Unknown error while parsing arguments\n");

    exitstatus = EXIT_FAILURE;

    goto end;

  }

  conffp = fopen(argfile, "r");

  if(conffp != NULL){

    char *org_line = NULL;

    size_t size = 0;

    ssize_t sret;

    char *p, *arg, *new_arg, *line;

    const char whitespace_delims[] = " \r\t\f\v\n";

    const char comment_delim[] = "#";

    while(true){

      sret = getline(&org_line, &size, conffp);

      if(sret == -1){

	break;

      }

      line = org_line;

      arg = strsep(&line, comment_delim);

      while((p = strsep(&arg, whitespace_delims)) != NULL){

	if(p[0] == '\0'){

	  continue;

	}

	new_arg = strdup(p);

	custom_argv = add_to_argv(custom_argv, &custom_argc, new_arg);

	if (custom_argv == NULL){

	  perror("add_to_argv");

	  exitstatus = EXIT_FAILURE;

	  goto end;

	}

      }

    }

    free(org_line);

  } else{

    /* Check for harmful errors and go to fallback. Other errors might

       not affect opening plugins */

    if (errno == EMFILE or errno == ENFILE or errno == ENOMEM){

      perror("fopen");

      exitstatus = EXIT_FAILURE;

      goto end;

    }

  }

  if(custom_argv != NULL){

    custom_argv[0] = argv[0];

    ret = argp_parse (&argp, custom_argc, custom_argv, 0, 0, &plugin_list);

    if (ret == ARGP_ERR_UNKNOWN){

      fprintf(stderr, "Unknown error while parsing arguments\n");

      exitstatus = EXIT_FAILURE;

      goto end;

    }

  }

  if(debug){

    for(plugin *p = plugin_list; p != NULL; p=p->next){

      fprintf(stderr, "Plugin: %s has %d arguments\n",

	      p->name ? p->name : "Global", p->argc - 1);

      for(char **a = p->argv; *a != NULL; a++){

	fprintf(stderr, "\tArg: %s\n", *a);

      }

      fprintf(stderr, "...and %u environment variables\n", p->envc);

      for(char **a = p->environ; *a != NULL; a++){

	fprintf(stderr, "\t%s\n", *a);

      }

    }

  }

  ret = setuid(uid);

  if (ret == -1){

    perror("setuid");

  }

  setgid(gid);

  if (ret == -1){

    perror("setgid");

  }

  dir = opendir(plugindir);

  if(dir == NULL){

    perror("Could not open plugin dir");

    exitstatus = EXIT_FAILURE;

    goto end;

  }

  /* Set the FD_CLOEXEC flag on the directory, if possible */

  {

    int dir_fd = dirfd(dir);

    if(dir_fd >= 0){

      ret = set_cloexec_flag(dir_fd);

      if(ret < 0){

	perror("set_cloexec_flag");

	exitstatus = EXIT_FAILURE;

	goto end;

      }

    }

  }

  FD_ZERO(&rfds_all);

  while(true){

    dirst = readdir(dir);

    // All directory entries have been processed

    if(dirst == NULL){

      if (errno == EBADF){

	perror("readdir");

	exitstatus = EXIT_FAILURE;

	goto end;

      }

      break;

    }

    d_name_len = strlen(dirst->d_name);

    // Ignore dotfiles, backup files and other junk

    {

      bool bad_name = false;

      const char const *bad_prefixes[] = { ".", "#", NULL };

      const char const *bad_suffixes[] = { "~", "#", ".dpkg-new",

					   ".dpkg-old",