sysdeps/mach/hurd/setgid.c

   1 /* Copyright (C) 1991-2018 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_t gid)
  31 {
  32   auth_t newauth;
  33   error_t err;
  34
  35   HURD_CRITICAL_BEGIN;
  36   __mutex_lock (&_hurd_id.lock);
  37   err = _hurd_check_ids ();
  38
  39   if (!err)
  40     {
  41       /* Make a new auth handle which has GID as the real gid,
  42          and as the first element in the list of effective gids.  */
  43
  44       gid_t *newgen, *newaux, auxbuf[2];
  45       size_t ngen, naux;
  46
  47       if (_hurd_id.gen.ngids == 0)
  48         {
  49           /* No effective gids now.  The new set will be just GID.  */
  50           newgen = &gid;
  51           ngen = 1;
  52         }
  53       else
  54         {
  55           _hurd_id.gen.gids[0] = gid;
  56           _hurd_id.valid = 0;
  57           newgen = _hurd_id.gen.gids;
  58           ngen = _hurd_id.gen.ngids;
  59         }
  60
  61       newaux = _hurd_id.aux.gids;
  62       naux = _hurd_id.aux.ngids;
  63       if (_hurd_id.gen.nuids > 0 && _hurd_id.gen.uids[0] == 0)
  64         {
  65           /* We are root; set the real and saved IDs too.  */
  66           _hurd_id.valid = 0;
  67           if (_hurd_id.aux.ngids < 2)
  68             {
  69               newaux = auxbuf;
  70               naux = 2;
  71             }
  72           newaux[0] = newaux[1] = gid;
  73         }
  74
  75       err = __USEPORT (AUTH, __auth_makeauth
  76                        (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
  77                         _hurd_id.gen.uids, _hurd_id.gen.nuids,
  78                         _hurd_id.aux.uids, _hurd_id.aux.nuids,
  79                         newgen, ngen, newaux, naux,
  80                         &newauth));
  81     }
  82   __mutex_unlock (&_hurd_id.lock);
  83   HURD_CRITICAL_END;
  84
  85   if (err)
  86     return __hurd_fail (err);
  87
  88   /* Install the new handle and reauthenticate everything.  */
  89   err = __setauth (newauth);
  90   __mach_port_deallocate (__mach_task_self (), newauth);
  91   return err;
  92 }
  93
  94 weak_alias (__setgid, setgid)