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