release/src/router/ppp/pppd/plugins/passprompt.c

   1 /*
   2  * passprompt.c - pppd plugin to invoke an external PAP password prompter
   3  *
   4  * Copyright 1999 Paul Mackerras, Alan Curry.
   5  *
   6  *  This program is free software; you can redistribute it and/or
   7  *  modify it under the terms of the GNU General Public License
   8  *  as published by the Free Software Foundation; either version
   9  *  2 of the License, or (at your option) any later version.
  10  */
  11 #include <errno.h>
  12 #include <unistd.h>
  13 #include <sys/wait.h>
  14 #include <syslog.h>
  15 #include "pppd.h"
  16
  17 char pppd_version[] = VERSION;
  18
  19 static char promptprog[PATH_MAX+1];
  20
  21 static option_t options[] = {
  22     { "promptprog", o_string, promptprog,
  23       "External PAP password prompting program",
  24       OPT_STATIC, NULL, PATH_MAX },
  25     { NULL }
  26 };
  27
  28 static int promptpass(char *user, char *passwd)
  29 {
  30     int p[2];
  31     pid_t kid;
  32     int readgood, wstat;
  33     size_t red;
  34
  35     if (promptprog[0] == 0 || access(promptprog, X_OK) < 0)
  36         return -1;      /* sorry, can't help */
  37
  38     if (!passwd)
  39         return 1;
  40
  41     if (pipe(p)) {
  42         warn("Can't make a pipe for %s", promptprog);
  43         return 0;
  44     }
  45     if ((kid = fork()) == (pid_t) -1) {
  46         warn("Can't fork to run %s", promptprog);
  47         close(p[0]);
  48         close(p[1]);
  49         return 0;
  50     }
  51     if (!kid) {
  52         /* we are the child, exec the program */
  53         char *argv[4], fdstr[32];
  54         sys_close();
  55         closelog();
  56         close(p[0]);
  57         seteuid(getuid());
  58         setegid(getgid());
  59         argv[0] = promptprog;
  60         argv[1] = user;
  61         argv[2] = remote_name;
  62         sprintf(fdstr, "%d", p[1]);
  63         argv[3] = fdstr;
  64         argv[4] = 0;
  65         execv(*argv, argv);
  66         _exit(127);
  67     }
  68
  69     /* we are the parent, read the password from the pipe */
  70     close(p[1]);
  71     readgood = 0;
  72     do {
  73         red = read(p[0], passwd + readgood, MAXSECRETLEN-1 - readgood);
  74         if (red == 0)
  75             break;
  76         if (red < 0) {
  77             error("Can't read secret from %s: %m", promptprog);
  78             readgood = -1;
  79             break;
  80         }
  81         readgood += red;
  82     } while (readgood < MAXSECRETLEN - 1);
  83     passwd[readgood] = 0;
  84     close(p[0]);
  85
  86     /* now wait for child to exit */
  87     while (waitpid(kid, &wstat, 0) < 0) {
  88         if (errno != EINTR) {
  89             warn("error waiting for %s: %m", promptprog);
  90             break;
  91         }
  92     }
  93
  94     if (readgood < 0)
  95         return 0;
  96     if (!WIFEXITED(wstat))
  97         warn("%s terminated abnormally", promptprog);
  98     if (WEXITSTATUS(wstat))
  99         warn("%s exited with code %d", promptprog, WEXITSTATUS(status));
 100
 101     return 1;
 102 }
 103
 104 void plugin_init(void)
 105 {
 106     add_options(options);
 107     pap_passwd_hook = promptpass;
 108 }