1  /* Copyright (C) 1993-2023 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     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <errno.h>
      19  #include <unistd.h>
      20  #include <hurd.h>
      21  #include <sys/types.h>
      22  #include <hurd/id.h>
      23  #include <string.h>
      24  
      25  /* Set the effective user ID of the calling process to GID.  */
      26  int
      27  setegid (gid_t gid)
      28  {
      29    auth_t newauth;
      30    error_t err;
      31  
      32  retry:
      33    HURD_CRITICAL_BEGIN;
      34    __mutex_lock (&_hurd_id.lock);
      35    err = _hurd_check_ids ();
      36  
      37    if (!err)
      38      {
      39        /* Make a new auth handle which has EGID as the first element in the
      40           list of effective gids.  */
      41  
      42        if (_hurd_id.gen.ngids > 0)
      43  	{
      44  	  _hurd_id.gen.gids[0] = gid;
      45  	  _hurd_id.valid = 0;
      46  	}
      47  
      48        err = __USEPORT (AUTH, __auth_makeauth
      49  		       (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
      50  			_hurd_id.gen.uids, _hurd_id.gen.nuids,
      51  			_hurd_id.aux.uids, _hurd_id.aux.nuids,
      52  			_hurd_id.gen.ngids ? _hurd_id.gen.gids : &gid,
      53  			_hurd_id.gen.ngids ?: 1,
      54  			_hurd_id.aux.gids, _hurd_id.aux.ngids,
      55  			&newauth));
      56      }
      57    __mutex_unlock (&_hurd_id.lock);
      58    HURD_CRITICAL_END;
      59    if (err == EINTR)
      60      /* Got a signal while inside an RPC of the critical section, retry again */
      61      goto retry;
      62  
      63    if (err)
      64      return __hurd_fail (err);
      65  
      66    /* Install the new handle and reauthenticate everything.  */
      67    err = __setauth (newauth);
      68    __mach_port_deallocate (__mach_task_self (), newauth);
      69    return err;
      70  }
      71  libc_hidden_def (setegid)