sysdeps/mach/hurd/setgid.c

   1 /* Copyright (C) 1991-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, see
  16    <http://www.gnu.org/licenses/>.  */
  17
  18 #include <errno.h>
  19 #include <unistd.h>
  20 #include <sys/types.h>
  21 #include <hurd.h>
  22 #include <hurd/id.h>
  23 #include <string.h>
  24
  25 /* Set the group ID of the calling process to UID.
  26    If the calling process is the super-user, the real
  27    and effective group IDs, and the saved set-group-ID to UID;
  28    if not, the effective group ID is set to GID.  */
  29 int
  30 __setgid (gid)
  31      gid_t gid;
  32 {
  33   auth_t newauth;
  34   error_t err;
  35
  36   HURD_CRITICAL_BEGIN;
  37   __mutex_lock (&_hurd_id.lock);
  38   err = _hurd_check_ids ();
  39
  40   if (!err)
  41     {
  42       /* Make a new auth handle which has GID as the real gid,
  43          and as the first element in the list of effective gids.  */
  44
  45       gid_t *newgen, *newaux, auxbuf[2];
  46       size_t ngen, naux;
  47
  48       if (_hurd_id.gen.ngids == 0)
  49         {
  50           /* No effective gids now.  The new set will be just GID.  */
  51           newgen = &gid;
  52           ngen = 1;
  53         }
  54       else
  55         {
  56           _hurd_id.gen.gids[0] = gid;
  57           _hurd_id.valid = 0;
  58           newgen = _hurd_id.gen.gids;
  59           ngen = _hurd_id.gen.ngids;
  60         }
  61
  62       newaux = _hurd_id.aux.gids;
  63       naux = _hurd_id.aux.ngids;
  64       if (_hurd_id.gen.nuids > 0 && _hurd_id.gen.uids[0] == 0)
  65         {
  66           /* We are root; set the real and saved IDs too.  */
  67           _hurd_id.valid = 0;
  68           if (_hurd_id.aux.ngids < 2)
  69             {
  70               newaux = auxbuf;
  71               naux = 2;
  72             }
  73           newaux[0] = newaux[1] = gid;
  74         }
  75
  76       err = __USEPORT (AUTH, __auth_makeauth
  77                        (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
  78                         _hurd_id.gen.uids, _hurd_id.gen.nuids,
  79                         _hurd_id.aux.uids, _hurd_id.aux.nuids,
  80                         newgen, ngen, newaux, naux,
  81                         &newauth));
  82     }
  83   __mutex_unlock (&_hurd_id.lock);
  84   HURD_CRITICAL_END;
  85
  86   if (err)
  87     return __hurd_fail (err);
  88
  89   /* Install the new handle and reauthenticate everything.  */
  90   err = __setauth (newauth);
  91   __mach_port_deallocate (__mach_task_self (), newauth);
  92   return err;
  93 }
  94
  95 weak_alias (__setgid, setgid)