usr/src/cmd/cmd-inet/usr.bin/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 <fcntl.h>
  14 #include <sys/wait.h>
  15 #include <syslog.h>
  16 #include "pppd.h"
  17
  18 static char promptprog[PATH_MAX+1];
  19
  20 static option_t options[] = {
  21     { "promptprog", o_string, promptprog,
  22       "External PAP password prompting program",
  23       OPT_STATIC, NULL, PATH_MAX },
  24     { NULL }
  25 };
  26
  27 static int promptpass(char *user, char *passwd)
  28 {
  29     int p[2];
  30     pid_t kid;
  31     int readgood, wstat;
  32     int red;
  33
  34     if (promptprog[0] == 0 || access(promptprog, X_OK) < 0)
  35         return -1;      /* sorry, can't help */
  36
  37     /* This occurs when we're probed for the ability to supply a password */
  38     if (user != NULL && passwd == NULL)
  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         (void) close(p[0]);
  48         (void) close(p[1]);
  49         return 0;
  50     }
  51     if (kid == (pid_t)0) {
  52         /* we are the child, exec the program */
  53         char *argv[5], fdstr[32];
  54
  55         sys_close();
  56         closelog();
  57         if (detached && p[1] <= 2) {
  58             (void) dup2(p[1], 3);
  59             p[1] = 3;
  60         }
  61         (void) close(p[0]);
  62         if (detached) {
  63             red = open("/etc/ppp/prompt-errors", O_WRONLY | O_APPEND | O_CREAT,
  64                 0600);
  65             (void) dup2(red, 1);
  66             (void) dup2(red, 2);
  67         }
  68         (void) seteuid(getuid());
  69         (void) setegid(getgid());
  70         argv[0] = promptprog;
  71         argv[1] = user == NULL ? "" : user;
  72         argv[2] = remote_name;
  73         slprintf(fdstr, sizeof (fdstr), "%d", p[1]);
  74         argv[3] = fdstr;
  75         argv[4] = NULL;
  76         (void) execv(*argv, argv);
  77         _exit(127);
  78     }
  79
  80     /* we are the parent, read the password from the pipe */
  81     (void) close(p[1]);
  82     readgood = 0;
  83     do {
  84         red = read(p[0], passwd + readgood, MAXSECRETLEN-1 - readgood);
  85         if (red == 0)
  86             break;
  87         if (red < 0) {
  88             if (errno == EINTR)
  89                 continue;
  90             error("Can't read secret from %s: %m", promptprog);
  91             readgood = -1;
  92             break;
  93         }
  94         readgood += red;
  95     } while (readgood < MAXSECRETLEN - 1);
  96     passwd[readgood] = 0;
  97     (void) close(p[0]);
  98
  99     /* now wait for child to exit */
 100     while (waitpid(kid, &wstat, 0) < 0) {
 101         if (errno != EINTR) {
 102             warn("error waiting for %s: %m", promptprog);
 103             break;
 104         }
 105     }
 106
 107     if (readgood < 0)
 108         return 0;
 109     if (readgood > 0 && passwd[--readgood] == '\n')
 110         passwd[readgood] = '\0';
 111     if (!WIFEXITED(wstat))
 112         warn("%s terminated abnormally", promptprog);
 113     if (WEXITSTATUS(wstat) != 0)
 114         warn("%s exited with code %d", promptprog, WEXITSTATUS(wstat));
 115
 116     return 1;
 117 }
 118
 119 void plugin_init(void)
 120 {
 121     add_options(options);
 122     pap_passwd_hook = promptpass;
 123 }