source/smbd/smbrun.c

   1 /*
   2    Unix SMB/Netbios implementation.
   3    Version 1.9.
   4    external program running routine
   5    Copyright (C) Andrew Tridgell 1992-1995
   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 #include "includes.h"
  23
  24
  25 /*******************************************************************
  26 close the low 3 fd's and open dev/null in their place
  27 ********************************************************************/
  28 static void close_fds(void)
  29 {
  30   int fd;
  31   int i;
  32   close(0); close(1); close(2);
  33   /* try and use up these file descriptors, so silly
  34      library routines writing to stdout etc won't cause havoc */
  35   for (i=0;i<3;i++) {
  36     fd = open("/dev/null",O_RDWR,0);
  37     if (fd < 0) fd = open("/dev/null",O_WRONLY,0);
  38     if (fd != i) return;
  39   }
  40 }
  41
  42
  43 /*
  44 This is a wrapper around the system call to allow commands to run correctly
  45 as non root from a program which is switching between root and non-root
  46
  47 It takes one argument as argv[1] and runs it after becoming a non-root
  48 user
  49 */
  50 int main(int argc,char *argv[])
  51 {
  52   close_fds();
  53
  54   if (getuid() != geteuid())
  55     {
  56       int uid,gid;
  57
  58       if (getuid() == 0)
  59         uid = geteuid();
  60       else
  61         uid = getuid();
  62
  63       if (getgid() == 0)
  64         gid = getegid();
  65       else
  66         gid = getgid();
  67
  68 #ifdef USE_SETRES
  69       setresgid(0,0,0);
  70       setresuid(0,0,0);
  71       setresgid(gid,gid,gid);
  72       setresuid(uid,uid,uid);
  73 #else
  74       setuid(0);
  75       seteuid(0);
  76       setgid(gid);
  77       setegid(gid);
  78       setuid(uid);
  79       seteuid(uid);
  80 #endif
  81
  82       if (getuid() != uid)
  83         return(3);
  84     }
  85
  86   if (geteuid() != getuid())
  87     return(1);
  88
  89   if (argc < 2)
  90     return(2);
  91
  92   /* this is to make sure that the system() call doesn't run forever */
  93   alarm(30);
  94
  95   return(system(argv[1]));
  96 }