sysdeps/mach/hurd/setuid.c

   1 /* Copyright (C) 1991-2017 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_t uid)
  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 UID as the real uid,
  42          and as the first element in the list of effective uids.  */
  43
  44       uid_t *newgen, *newaux, auxbuf[2];
  45       size_t ngen, naux;
  46
  47       newaux = _hurd_id.aux.uids;
  48       naux = _hurd_id.aux.nuids;
  49       if (_hurd_id.gen.nuids == 0)
  50         {
  51           /* No effective uids now.  The new set will be just UID.  */
  52           newgen = &uid;
  53           ngen = 1;
  54         }
  55       else if (_hurd_id.gen.uids[0] == 0)
  56         {
  57           /* We are root; set the effective, real, and saved to UID.  */
  58           _hurd_id.gen.uids[0] = uid;
  59           _hurd_id.valid = 0;
  60           newgen = _hurd_id.gen.uids;
  61           ngen = _hurd_id.gen.nuids;
  62           if (_hurd_id.aux.nuids < 2)
  63             {
  64               newaux = auxbuf;
  65               naux = 2;
  66             }
  67           newaux[0] = newaux[1] = uid;
  68         }
  69       else
  70         {
  71           /* We are not root; just change the effective UID.  */
  72           /* XXX that implies an unprivileged setuid(0) will give
  73              the caller root, no questions asked! */
  74           _hurd_id.gen.uids[0] = uid;
  75           _hurd_id.valid = 0;
  76           newgen = _hurd_id.gen.uids;
  77           ngen = _hurd_id.gen.nuids;
  78         }
  79
  80       err = __USEPORT (AUTH, __auth_makeauth
  81                        (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
  82                         newgen, ngen, newaux, naux,
  83                         _hurd_id.gen.gids, _hurd_id.gen.ngids,
  84                         _hurd_id.aux.gids, _hurd_id.aux.ngids,
  85                         &newauth));
  86     }
  87   __mutex_unlock (&_hurd_id.lock);
  88   HURD_CRITICAL_END;
  89
  90   if (err)
  91     return __hurd_fail (err);
  92
  93   /* Install the new handle and reauthenticate everything.  */
  94   err = __setauth (newauth);
  95   __mach_port_deallocate (__mach_task_self (), newauth);
  96   return err;
  97 }
  98
  99 weak_alias (__setuid, setuid)