1/* setresuid -- set real user ID, effective user ID, and saved-set user ID
2 Copyright (C) 2002-2024 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 user ID, effective user ID, and saved-set user ID,
25 of the calling process to RUID, EUID, and SUID, respectively. */
26int
27__setresuid (uid_t ruid, uid_t euid, uid_t suid)
28{
29 auth_t newauth;
30 error_t err;
31
32retry:
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 EUID as the first element in the
40 list of effective uids. */
41
42 uid_t *newgen, *newaux;
43 uid_t auxs[2] = { ruid, suid };
44 size_t ngen, naux;
45
46 newgen = _hurd_id.gen.uids;
47 ngen = _hurd_id.gen.nuids;
48 if (euid != -1)
49 {
50 if (_hurd_id.gen.nuids == 0)
51 {
52 /* No effective uids now. The new set will be just UID. */
53 newgen = &euid;
54 ngen = 1;
55 }
56 else
57 {
58 _hurd_id.gen.uids[0] = euid;
59 _hurd_id.valid = 0;
60 }
61 }
62
63 newaux = _hurd_id.aux.uids;
64 naux = _hurd_id.aux.nuids;
65 if (ruid != -1)
66 {
67 if (_hurd_id.aux.nuids == 0)
68 {
69 newaux = &ruid;
70 naux = 1;
71 }
72 else
73 {
74 _hurd_id.aux.uids[0] = ruid;
75 _hurd_id.valid = 0;
76 }
77 }
78
79 if (suid != -1)
80 {
81 if (ruid == -1)
82 {
83 if (_hurd_id.aux.nuids >= 1)
84 auxs[0] = _hurd_id.aux.uids[0];
85 else if (_hurd_id.gen.nuids >= 1)
86 auxs[0] = _hurd_id.gen.uids[0];
87 else
88 /* Not even an effective UID.
89 Fall back to the only UID we have. */
90 auxs[0] = suid;
91 }
92 if (_hurd_id.aux.nuids <= 1)
93 {
94 /* No saved uids now. The new set will be just UID. */
95 newaux = auxs;
96 naux = 2;
97 }
98 else
99 {
100 _hurd_id.aux.uids[1] = suid;
101 _hurd_id.valid = 0;
102 }
103 }
104
105 err = __USEPORT (AUTH, __auth_makeauth
106 (port, NULL, MACH_MSG_TYPE_COPY_SEND, 0,
107 newgen, ngen, newaux, naux,
108 _hurd_id.gen.gids, _hurd_id.gen.ngids,
109 _hurd_id.aux.gids, _hurd_id.aux.ngids,
110 &newauth));
111 }
112
113 __mutex_unlock (&_hurd_id.lock);
114 HURD_CRITICAL_END;
115 if (err == EINTR)
116 /* Got a signal while inside an RPC of the critical section, retry again */
117 goto retry;
118
119 if (err)
120 return __hurd_fail (err);
121
122 /* Install the new handle and reauthenticate everything. */
123 err = __setauth (newauth);
124 __mach_port_deallocate (__mach_task_self (), newauth);
125 return err;
126}
127libc_hidden_def (__setresuid)
128weak_alias (__setresuid, setresuid)
129

source code of glibc/sysdeps/mach/hurd/setresuid.c