1 /* Copyright (C) 1991-2021 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 <sys/types.h>
21 #include <hurd.h>
22 #include <hurd/id.h>
23 #include <string.h>
24
25 /* Set the group ID of the calling process to UID.
26 If the calling process is the super-user, the real
27 and effective group IDs, and the saved set-group-ID to UID;
28 if not, the effective group ID is set to GID. */
29 int
__setgid(gid_t gid)30 __setgid (gid_t gid)
31 {
32 auth_t newauth;
33 error_t err;
34
35 retry:
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 GID as the real gid,
43 and as the first element in the list of effective gids. */
44
45 gid_t *newgen, *newaux, auxbuf[2];
46 size_t ngen, naux;
47
48 if (_hurd_id.gen.ngids == 0)
49 {
50 /* No effective gids now. The new set will be just GID. */
51 newgen = &gid;
52 ngen = 1;
53 }
54 else
55 {
56 _hurd_id.gen.gids[0] = gid;
57 _hurd_id.valid = 0;
58 newgen = _hurd_id.gen.gids;
59 ngen = _hurd_id.gen.ngids;
60 }
61
62 newaux = _hurd_id.aux.gids;
63 naux = _hurd_id.aux.ngids;
64 if (_hurd_id.gen.nuids > 0 && _hurd_id.gen.uids[0] == 0)
65 {
66 /* We are root; set the real and saved IDs too. */
67 _hurd_id.valid = 0;
68 if (_hurd_id.aux.ngids < 2)
69 {
70 newaux = auxbuf;
71 naux = 2;
72 }
73 newaux[0] = newaux[1] = gid;
74 }
75
76 err = __USEPORT (AUTH, __auth_makeauth
77 (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
78 _hurd_id.gen.uids, _hurd_id.gen.nuids,
79 _hurd_id.aux.uids, _hurd_id.aux.nuids,
80 newgen, ngen, newaux, naux,
81 &newauth));
82 }
83 __mutex_unlock (&_hurd_id.lock);
84 HURD_CRITICAL_END;
85 if (err == EINTR)
86 /* Got a signal while inside an RPC of the critical section, retry again */
87 goto retry;
88
89 if (err)
90 return __hurd_fail (err);
91
92 /* Install the new handle and reauthenticate everything. */
93 err = __setauth (newauth);
94 __mach_port_deallocate (__mach_task_self (), newauth);
95 return err;
96 }
97
98 weak_alias (__setgid, setgid)
99