external/ibm-public/postfix/dist/src/util/set_eugid.c

   1 /*      $NetBSD$        */
   2
   3 /*++
   4 /* NAME
   5 /*      set_eugid 3
   6 /* SUMMARY
   7 /*      set effective user and group attributes
   8 /* SYNOPSIS
   9 /*      #include <set_eugid.h>
  10 /*
  11 /*      void    set_eugid(euid, egid)
  12 /*      uid_t   euid;
  13 /*      gid_t   egid;
  14 /*
  15 /*      void    SAVE_AND_SET_EUGID(uid, gid)
  16 /*      uid_t   uid;
  17 /*      gid_t gid;
  18 /*
  19 /*      void    RESTORE_SAVED_EUGID()
  20 /* DESCRIPTION
  21 /*      set_eugid() sets the effective user and group process attributes
  22 /*      and updates the process group access list to be just the specified
  23 /*      effective group id.
  24 /*
  25 /*      SAVE_AND_SET_EUGID() opens a block that executes with the
  26 /*      specified privilege. RESTORE_SAVED_EUGID() closes the block.
  27 /* DIAGNOSTICS
  28 /*      All system call errors are fatal.
  29 /* SEE ALSO
  30 /*      seteuid(2), setegid(2), setgroups(2)
  31 /* LICENSE
  32 /* .ad
  33 /* .fi
  34 /*      The Secure Mailer license must be distributed with this software.
  35 /* AUTHOR(S)
  36 /*      Wietse Venema
  37 /*      IBM T.J. Watson Research
  38 /*      P.O. Box 704
  39 /*      Yorktown Heights, NY 10598, USA
  40 /*--*/
  41
  42 /* System library. */
  43
  44 #include <sys_defs.h>
  45 #include <unistd.h>
  46 #include <grp.h>
  47 #include <errno.h>
  48
  49 /* Utility library. */
  50
  51 #include "msg.h"
  52 #include "set_eugid.h"
  53
  54 /* set_eugid - set effective user and group attributes */
  55
  56 void    set_eugid(uid_t euid, gid_t egid)
  57 {
  58     int     saved_errno = errno;
  59
  60     if (geteuid() != 0)
  61         if (seteuid(0))
  62             msg_fatal("set_eugid: seteuid(0): %m");
  63     if (setegid(egid) < 0)
  64         msg_fatal("set_eugid: setegid(%ld): %m", (long) egid);
  65     if (setgroups(1, &egid) < 0)
  66         msg_fatal("set_eugid: setgroups(%ld): %m", (long) egid);
  67     if (euid != 0 && seteuid(euid) < 0)
  68         msg_fatal("set_eugid: seteuid(%ld): %m", (long) euid);
  69     if (msg_verbose)
  70         msg_info("set_eugid: euid %ld egid %ld", (long) euid, (long) egid);
  71     errno = saved_errno;
  72 }