source/smbd/chgpasswd.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    Samba utility functions
   5    Copyright (C) Andrew Tridgell 1992-1997
   6
   7    This program is free software; you can redistribute it and/or modify
   8    it under the terms of the GNU General Public License as published by
   9    the Free Software Foundation; either version 2 of the License, or
  10    (at your option) any later version.
  11
  12    This program is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15    GNU General Public License for more details.
  16
  17    You should have received a copy of the GNU General Public License
  18    along with this program; if not, write to the Free Software
  19    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 /* fork a child process to exec passwd and write to its
  23 * tty to change a users password. This is running as the
  24 * user who is attempting to change the password.
  25 */
  26
  27 /*
  28  * This code was copied/borrowed and stolen from various sources.
  29  * The primary source was the poppasswd.c from the authors of POPMail. This software
  30  * was included as a client to change passwords using the 'passwd' program
  31  * on the remote machine.
  32  *
  33  * This routine is called by set_user_password() in password.c only if ALLOW_PASSWORD_CHANGE
  34  * is defined in the compiler directives located in the Makefile.
  35  *
  36  * This code has been hacked by Bob Nance (nance@niehs.nih.gov) and Evan Patterson
  37  * (patters2@niehs.nih.gov) at the National Institute of Environmental Health Sciences
  38  * and rights to modify, distribute or incorporate this change to the CAP suite or
  39  * using it for any other reason are granted, so long as this disclaimer is left intact.
  40  */
  41
  42 /*
  43    This code was hacked considerably for inclusion in Samba, primarily
  44    by Andrew.Tridgell@anu.edu.au. The biggest change was the addition
  45    of the "password chat" option, which allows the easy runtime
  46    specification of the expected sequence of events to change a
  47    password.
  48    */
  49
  50 #include "includes.h"
  51
  52 extern int DEBUGLEVEL;
  53
  54 #ifdef ALLOW_CHANGE_PASSWORD
  55
  56 #define MINPASSWDLENGTH 5
  57 #define BUFSIZE 512
  58
  59 static int findpty(char **slave)
  60 {
  61   int master;
  62 #if defined(SVR4) || defined(SUNOS5)
  63   extern char *ptsname();
  64 #else /* defined(SVR4) || defined(SUNOS5) */
  65   static char line[12];
  66   void *dirp;
  67   char *dpname;
  68 #endif /* defined(SVR4) || defined(SUNOS5) */
  69
  70 #if defined(SVR4) || defined(SUNOS5)
  71   if ((master = open("/dev/ptmx", O_RDWR)) >= 1) {
  72     grantpt(master);
  73     unlockpt(master);
  74     *slave = ptsname(master);
  75     return (master);
  76   }
  77 #else /* defined(SVR4) || defined(SUNOS5) */
  78   strcpy( line, "/dev/ptyXX" );
  79
  80   dirp = OpenDir(-1, "/dev", True);
  81   if (!dirp) return(-1);
  82   while ((dpname = ReadDirName(dirp)) != NULL) {
  83     if (strncmp(dpname, "pty", 3) == 0 && strlen(dpname) == 5) {
  84       DEBUG(3,("pty: try to open %s, line was %s\n", dpname, line ) );
  85       line[8] = dpname[3];
  86       line[9] = dpname[4];
  87       if ((master = open(line, O_RDWR)) >= 0) {
  88         DEBUG(3,("pty: opened %s\n", line ) );
  89         line[5] = 't';
  90         *slave = line;
  91         CloseDir(dirp);
  92         return (master);
  93       }
  94     }
  95   }
  96   CloseDir(dirp);
  97 #endif /* defined(SVR4) || defined(SUNOS5) */
  98   return (-1);
  99 }
 100
 101 static int dochild(int master,char *slavedev, char *name, char *passwordprogram)
 102 {
 103   int slave;
 104   struct termios stermios;
 105   struct passwd *pass = Get_Pwnam(name,True);
 106   int gid = pass->pw_gid;
 107   int uid = pass->pw_uid;
 108
 109 #ifdef USE_SETRES
 110   setresuid(0,0,0);
 111 #else /* USE_SETRES */
 112   setuid(0);
 113 #endif /* USE_SETRES */
 114
 115   /* Start new session - gets rid of controlling terminal. */
 116   if (setsid() < 0) {
 117     DEBUG(3,("Weirdness, couldn't let go of controlling terminal\n"));
 118     return(False);
 119   }
 120
 121   /* Open slave pty and acquire as new controlling terminal. */
 122   if ((slave = open(slavedev, O_RDWR)) < 0) {
 123     DEBUG(3,("More weirdness, could not open %s\n",
 124              slavedev));
 125     return(False);
 126   }
 127 #if defined(SVR4) || defined(SUNOS5)
 128   ioctl(slave, I_PUSH, "ptem");
 129   ioctl(slave, I_PUSH, "ldterm");
 130 #else /* defined(SVR4) || defined(SUNOS5) */
 131   if (ioctl(slave,TIOCSCTTY,0) <0) {
 132      DEBUG(3,("Error in ioctl call for slave pty\n"));
 133      /* return(False); */
 134   }
 135 #endif /* defined(SVR4) || defined(SUNOS5) */
 136
 137   /* Close master. */
 138   close(master);
 139
 140   /* Make slave stdin/out/err of child. */
 141
 142   if (dup2(slave, STDIN_FILENO) != STDIN_FILENO) {
 143     DEBUG(3,("Could not re-direct stdin\n"));
 144     return(False);
 145   }
 146   if (dup2(slave, STDOUT_FILENO) != STDOUT_FILENO) {
 147     DEBUG(3,("Could not re-direct stdout\n"));
 148     return(False);
 149   }
 150   if (dup2(slave, STDERR_FILENO) != STDERR_FILENO) {
 151     DEBUG(3,("Could not re-direct stderr\n"));
 152     return(False);
 153   }
 154   if (slave > 2) close(slave);
 155
 156   /* Set proper terminal attributes - no echo, canonical input processing,
 157      no map NL to CR/NL on output. */
 158
 159   if (tcgetattr(0, &stermios) < 0) {
 160     DEBUG(3,("could not read default terminal attributes on pty\n"));
 161     return(False);
 162   }
 163   stermios.c_lflag &= ~(ECHO | ECHOE | ECHOK | ECHONL);
 164   stermios.c_lflag |= ICANON;
 165   stermios.c_oflag &= ~(ONLCR);
 166   if (tcsetattr(0, TCSANOW, &stermios) < 0) {
 167     DEBUG(3,("could not set attributes of pty\n"));
 168     return(False);
 169   }
 170
 171   /* make us completely into the right uid */
 172 #ifdef USE_SETRES
 173   setresgid(0,0,0);
 174   setresuid(0,0,0);
 175   setresgid(gid,gid,gid);
 176   setresuid(uid,uid,uid);
 177 #else
 178   setuid(0);
 179   seteuid(0);
 180   setgid(gid);
 181   setegid(gid);
 182   setuid(uid);
 183   seteuid(uid);
 184 #endif
 185
 186   /* execl() password-change application */
 187   if (execl("/bin/sh","sh","-c",passwordprogram,NULL) < 0) {
 188     DEBUG(3,("Bad status returned from %s\n",passwordprogram));
 189     return(False);
 190   }
 191   return(True);
 192 }
 193
 194 static int expect(int master,char *expected,char *buf)
 195 {
 196   int n, m;
 197
 198   n = 0;
 199   buf[0] = 0;
 200   while (1) {
 201     if (n >= BUFSIZE-1) {
 202       return False;
 203     }
 204
 205     /* allow 4 seconds for some output to appear */
 206     m = read_with_timeout(master, buf+n, 1, BUFSIZE-1-n, 4000);
 207     if (m < 0)
 208       return False;
 209
 210     n += m;
 211     buf[n] = 0;
 212
 213     {
 214       pstring s1,s2;
 215       pstrcpy(s1,buf);
 216       pstrcpy(s2,expected);
 217       if (do_match(s1, s2, False))
 218         return(True);
 219     }
 220   }
 221 }
 222
 223 static void pwd_sub(char *buf)
 224 {
 225   string_sub(buf,"\\n","\n");
 226   string_sub(buf,"\\r","\r");
 227   string_sub(buf,"\\s"," ");
 228   string_sub(buf,"\\t","\t");
 229 }
 230
 231 static void writestring(int fd,char *s)
 232 {
 233   int l;
 234
 235   l = strlen (s);
 236   write (fd, s, l);
 237 }
 238
 239
 240 static int talktochild(int master, char *chatsequence)
 241 {
 242   char buf[BUFSIZE];
 243   int count=0;
 244   char *ptr=chatsequence;
 245   fstring chatbuf;
 246
 247   *buf = 0;
 248   sleep(1);
 249
 250   while (next_token(&ptr,chatbuf,NULL)) {
 251     BOOL ok=True;
 252     count++;
 253     pwd_sub(chatbuf);
 254     if (!strequal(chatbuf,"."))
 255       ok = expect(master,chatbuf,buf);
 256
 257 #if DEBUG_PASSWORD
 258       DEBUG(100,("chatbuf=[%s] responsebuf=[%s]\n",chatbuf,buf));
 259 #endif
 260
 261     if (!ok) {
 262       DEBUG(3,("response %d incorrect\n",count));
 263       return(False);
 264     }
 265
 266     if (!next_token(&ptr,chatbuf,NULL)) break;
 267     pwd_sub(chatbuf);
 268     if (!strequal(chatbuf,"."))
 269       writestring(master,chatbuf);
 270
 271 #if DEBUG_PASSWORD
 272     DEBUG(100,("sendbuf=[%s]\n",chatbuf));
 273 #endif
 274   }
 275
 276   if (count<1) return(False);
 277
 278   return (True);
 279 }
 280
 281
 282 BOOL chat_with_program(char *passwordprogram,char *name,char *chatsequence)
 283 {
 284   char *slavedev;
 285   int master;
 286   pid_t pid, wpid;
 287   int wstat;
 288   BOOL chstat;
 289
 290   /* allocate a pseudo-terminal device */
 291   if ((master = findpty (&slavedev)) < 0) {
 292     DEBUG(3,("Cannot Allocate pty for password change: %s",name));
 293     return(False);
 294   }
 295
 296   if ((pid = fork()) < 0) {
 297     DEBUG(3,("Cannot fork() child for password change: %s",name));
 298     return(False);
 299   }
 300
 301   /* we now have a pty */
 302   if (pid > 0){                 /* This is the parent process */
 303     if ((chstat = talktochild(master, chatsequence)) == False) {
 304       DEBUG(3,("Child failed to change password: %s\n",name));
 305       kill(pid, SIGKILL); /* be sure to end this process */
 306       return(False);
 307     }
 308     if ((wpid = sys_waitpid(pid, &wstat, 0)) < 0) {
 309       DEBUG(3,("The process is no longer waiting!\n\n"));
 310       return(False);
 311     }
 312     if (pid != wpid) {
 313       DEBUG(3,("We were waiting for the wrong process ID\n"));
 314       return(False);
 315     }
 316     if (WIFEXITED(wstat) == 0) {
 317       DEBUG(3,("The process exited while we were waiting\n"));
 318       return(False);
 319     }
 320     if (WEXITSTATUS(wstat) != 0) {
 321       DEBUG(3,("The status of the process exiting was %d\n", wstat));
 322       return(False);
 323     }
 324
 325   } else {
 326     /* CHILD */
 327
 328     /* make sure it doesn't freeze */
 329     alarm(20);
 330
 331     DEBUG(3,("Dochild for user %s (uid=%d,gid=%d)\n",name,getuid(),getgid()));
 332     chstat = dochild(master, slavedev, name, passwordprogram);
 333   }
 334   DEBUG(3,("Password change %ssuccessful for user %s\n", (chstat?"":"un"), name));
 335   return (chstat);
 336 }
 337
 338
 339 BOOL chgpasswd(char *name,char *oldpass,char *newpass)
 340 {
 341   pstring passwordprogram;
 342   pstring chatsequence;
 343
 344   strlower(name);
 345   DEBUG(3,("Password change for user: %s\n",name));
 346
 347 #if DEBUG_PASSWORD
 348   DEBUG(100,("Passwords: old=%s new=%s\n",oldpass,newpass));
 349 #endif
 350
 351   /* Take the passed information and test it for minimum criteria */
 352   /* Minimum password length */
 353   if (strlen(newpass) < MINPASSWDLENGTH) /* too short, must be at least MINPASSWDLENGTH */
 354     {
 355       DEBUG(2,("Password Change: %s, New password is shorter than MINPASSWDLENGTH\n",name));
 356       return (False);           /* inform the user */
 357     }
 358
 359   /* Password is same as old password */
 360   if (strcmp(oldpass,newpass) == 0) /* don't allow same password */
 361     {
 362       DEBUG(2,("Password Change: %s, New password is same as old\n",name)); /* log the attempt */
 363       return (False);           /* inform the user */
 364     }
 365
 366 #if (defined(PASSWD_PROGRAM) && defined(PASSWD_CHAT))
 367   pstrcpy(passwordprogram,PASSWD_PROGRAM);
 368   pstrcpy(chatsequence,PASSWD_CHAT);
 369 #else
 370   pstrcpy(passwordprogram,lp_passwd_program());
 371   pstrcpy(chatsequence,lp_passwd_chat());
 372 #endif
 373
 374   if (!*chatsequence) {
 375     DEBUG(2,("Null chat sequence - no password changing\n"));
 376     return(False);
 377   }
 378
 379   if (!*passwordprogram) {
 380     DEBUG(2,("Null password program - no password changing\n"));
 381     return(False);
 382   }
 383
 384   string_sub(passwordprogram,"%u",name);
 385   string_sub(passwordprogram,"%o",oldpass);
 386   string_sub(passwordprogram,"%n",newpass);
 387
 388   string_sub(chatsequence,"%u",name);
 389   string_sub(chatsequence,"%o",oldpass);
 390   string_sub(chatsequence,"%n",newpass);
 391   return(chat_with_program(passwordprogram,name,chatsequence));
 392 }
 393
 394 #else
 395 BOOL chgpasswd(char *name,char *oldpass,char *newpass)
 396 {
 397   DEBUG(0,("Password changing not compiled in (user=%s)\n",name));
 398   return(False);
 399 }
 400 #endif