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glibc  2.9
setuid.c
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00001 /* Copyright (C) 1991, 92, 93, 94, 95, 97 Free Software Foundation, Inc.
00002    This file is part of the GNU C Library.
00003 
00004    The GNU C Library is free software; you can redistribute it and/or
00005    modify it under the terms of the GNU Lesser General Public
00006    License as published by the Free Software Foundation; either
00007    version 2.1 of the License, or (at your option) any later version.
00008 
00009    The GNU C Library is distributed in the hope that it will be useful,
00010    but WITHOUT ANY WARRANTY; without even the implied warranty of
00011    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00012    Lesser General Public License for more details.
00013 
00014    You should have received a copy of the GNU Lesser General Public
00015    License along with the GNU C Library; if not, write to the Free
00016    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00017    02111-1307 USA.  */
00018 
00019 #include <errno.h>
00020 #include <unistd.h>
00021 #include <sys/types.h>
00022 #include <hurd.h>
00023 #include <hurd/id.h>
00024 #include <string.h>
00025 
00026 /* Set the user ID of the calling process to UID.
00027    If the calling process is the super-user, the real
00028    and effective user IDs, and the saved set-user-ID to UID;
00029    if not, the effective user ID is set to UID.  */
00030 int
00031 __setuid (uid)
00032      uid_t uid;
00033 {
00034   auth_t newauth;
00035   error_t err;
00036 
00037   HURD_CRITICAL_BEGIN;
00038   __mutex_lock (&_hurd_id.lock);
00039   err = _hurd_check_ids ();
00040 
00041   if (!err)
00042     {
00043       /* Make a new auth handle which has UID as the real uid,
00044         and as the first element in the list of effective uids.  */
00045 
00046       uid_t *newgen, *newaux, auxbuf[2];
00047       size_t ngen, naux;
00048 
00049       newaux = _hurd_id.aux.uids;
00050       naux = _hurd_id.aux.nuids;
00051       if (_hurd_id.gen.nuids == 0)
00052        {
00053          /* No effective uids now.  The new set will be just UID.  */
00054          newgen = &uid;
00055          ngen = 1;
00056        }
00057       else if (_hurd_id.gen.uids[0] == 0)
00058        {
00059          /* We are root; set the effective, real, and saved to UID.  */
00060          _hurd_id.gen.uids[0] = uid;
00061          _hurd_id.valid = 0;
00062          newgen = _hurd_id.gen.uids;
00063          ngen = _hurd_id.gen.nuids;
00064          if (_hurd_id.aux.nuids < 2)
00065            {
00066              newaux = auxbuf;
00067              naux = 2;
00068            }
00069          newaux[0] = newaux[1] = uid;
00070        }
00071       else
00072        {
00073          /* We are not root; just change the effective UID.  */
00074          /* XXX that implies an unprivileged setuid(0) will give
00075             the caller root, no questions asked! */
00076          _hurd_id.gen.uids[0] = uid;
00077          _hurd_id.valid = 0;
00078          newgen = _hurd_id.gen.uids;
00079          ngen = _hurd_id.gen.nuids;
00080        }
00081 
00082       err = __USEPORT (AUTH, __auth_makeauth
00083                      (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
00084                      newgen, ngen, newaux, naux,
00085                      _hurd_id.gen.gids, _hurd_id.gen.ngids,
00086                      _hurd_id.aux.gids, _hurd_id.aux.ngids,
00087                      &newauth));
00088     }
00089   __mutex_unlock (&_hurd_id.lock);
00090   HURD_CRITICAL_END;
00091 
00092   if (err)
00093     return __hurd_fail (err);
00094 
00095   /* Install the new handle and reauthenticate everything.  */
00096   err = __setauth (newauth);
00097   __mach_port_deallocate (__mach_task_self (), newauth);
00098   return err;
00099 }
00100 
00101 weak_alias (__setuid, setuid)