sysdeps/mach/hurd/setresgid.c

   1 /* setresgid -- set real group ID, effective group ID, and saved-set group ID
   2    Copyright (C) 2002-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <unistd.h>
  21 #include <hurd.h>
  22 #include <hurd/id.h>
  23
  24 /* Set the real group ID, effective group ID, and saved-set group ID,
  25    of the calling process to RGID, EGID, and SGID, respectively.  */
  26 int
  27 __setresgid (gid_t rgid, gid_t egid, gid_t sgid)
  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       uid_t *newgen, *newaux;
  43       uid_t auxs[2] = { rgid, sgid };
  44       size_t ngen, naux;
  45
  46       newgen = _hurd_id.gen.gids;
  47       ngen = _hurd_id.gen.ngids;
  48       if (egid != -1)
  49         {
  50           if (_hurd_id.gen.ngids == 0)
  51             {
  52               /* No effective gids now.  The new set will be just UID.  */
  53               newgen = &egid;
  54               ngen = 1;
  55             }
  56           else
  57             {
  58               _hurd_id.gen.gids[0] = egid;
  59               _hurd_id.valid = 0;
  60             }
  61         }
  62
  63       newaux = _hurd_id.aux.gids;
  64       naux = _hurd_id.aux.ngids;
  65       if (rgid != -1)
  66         {
  67           if (_hurd_id.aux.ngids == 0)
  68             {
  69               newaux = &rgid;
  70               naux = 1;
  71             }
  72           else
  73             {
  74               _hurd_id.aux.gids[0] = rgid;
  75               _hurd_id.valid = 0;
  76             }
  77         }
  78
  79       if (sgid != -1)
  80         {
  81           if (rgid == -1)
  82             {
  83               if (_hurd_id.aux.ngids >= 1)
  84                 auxs[0] = _hurd_id.aux.gids[0];
  85               else if (_hurd_id.gen.ngids >= 1)
  86                 auxs[0] = _hurd_id.gen.gids[0];
  87               else
  88                 /* Not even an effective GID.
  89                    Fall back to the only GID we have. */
  90                 auxs[0] = sgid;
  91             }
  92           if (_hurd_id.aux.ngids <= 1)
  93             {
  94               /* No saved gids now.  The new set will be just UID.  */
  95               newaux = auxs;
  96               naux = 2;
  97             }
  98           else
  99             {
 100               _hurd_id.aux.gids[1] = sgid;
 101               _hurd_id.valid = 0;
 102             }
 103         }
 104
 105       err = __USEPORT (AUTH, __auth_makeauth
 106                        (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
 107                         _hurd_id.gen.uids, _hurd_id.gen.nuids,
 108                         _hurd_id.aux.uids, _hurd_id.aux.nuids,
 109                         newgen, ngen, newaux, naux,
 110                         &newauth));
 111     }
 112   __mutex_unlock (&_hurd_id.lock);
 113   HURD_CRITICAL_END;
 114   if (err == EINTR)
 115     /* Got a signal while inside an RPC of the critical section, retry again */
 116     goto retry;
 117
 118   if (err)
 119     return __hurd_fail (err);
 120
 121   /* Install the new handle and reauthenticate everything.  */
 122   err = __setauth (newauth);
 123   __mach_port_deallocate (__mach_task_self (), newauth);
 124   return err;
 125 }
 126 libc_hidden_def (__setresgid)
 127 weak_alias (__setresgid, setresgid)