source/smbd/chgpasswd.c

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