sysdeps/mach/hurd/setuid.c

   1 /* Copyright (C) 1991-2015 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 user ID of the calling process to UID.
  26    If the calling process is the super-user, the real
  27    and effective user IDs, and the saved set-user-ID to UID;
  28    if not, the effective user ID is set to UID.  */
  29 int
  30 __setuid (uid)
  31      uid_t uid;
  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 UID as the real uid,
  43          and as the first element in the list of effective uids.  */
  44
  45       uid_t *newgen, *newaux, auxbuf[2];
  46       size_t ngen, naux;
  47
  48       newaux = _hurd_id.aux.uids;
  49       naux = _hurd_id.aux.nuids;
  50       if (_hurd_id.gen.nuids == 0)
  51         {
  52           /* No effective uids now.  The new set will be just UID.  */
  53           newgen = &uid;
  54           ngen = 1;
  55         }
  56       else if (_hurd_id.gen.uids[0] == 0)
  57         {
  58           /* We are root; set the effective, real, and saved to UID.  */
  59           _hurd_id.gen.uids[0] = uid;
  60           _hurd_id.valid = 0;
  61           newgen = _hurd_id.gen.uids;
  62           ngen = _hurd_id.gen.nuids;
  63           if (_hurd_id.aux.nuids < 2)
  64             {
  65               newaux = auxbuf;
  66               naux = 2;
  67             }
  68           newaux[0] = newaux[1] = uid;
  69         }
  70       else
  71         {
  72           /* We are not root; just change the effective UID.  */
  73           /* XXX that implies an unprivileged setuid(0) will give
  74              the caller root, no questions asked! */
  75           _hurd_id.gen.uids[0] = uid;
  76           _hurd_id.valid = 0;
  77           newgen = _hurd_id.gen.uids;
  78           ngen = _hurd_id.gen.nuids;
  79         }
  80
  81       err = __USEPORT (AUTH, __auth_makeauth
  82                        (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
  83                         newgen, ngen, newaux, naux,
  84                         _hurd_id.gen.gids, _hurd_id.gen.ngids,
  85                         _hurd_id.aux.gids, _hurd_id.aux.ngids,
  86                         &newauth));
  87     }
  88   __mutex_unlock (&_hurd_id.lock);
  89   HURD_CRITICAL_END;
  90
  91   if (err)
  92     return __hurd_fail (err);
  93
  94   /* Install the new handle and reauthenticate everything.  */
  95   err = __setauth (newauth);
  96   __mach_port_deallocate (__mach_task_self (), newauth);
  97   return err;
  98 }
  99
 100 weak_alias (__setuid, setuid)