1/*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2001-2002 Chris D. Faulhaber
5 * All rights reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in the
14 *    documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29#include <sys/cdefs.h>
30#if 0
31__FBSDID("$FreeBSD: head/lib/libc/posix1e/acl_calc_mask.c 326193 2017-11-25 17:12:48Z pfg $");
32#else
33__RCSID("$NetBSD: acl_calc_mask.c,v 1.2 2024/01/20 14:52:48 christos Exp $");
34#endif
35
36#include "namespace.h"
37
38#include <sys/types.h>
39#include <sys/acl.h>
40
41#include <errno.h>
42#include <stdio.h>
43
44#include "acl_support.h"
45
46/*
47 * acl_calc_mask() (23.4.2): calculate and set the permissions
48 * associated with the ACL_MASK ACL entry.  If the ACL already
49 * contains an ACL_MASK entry, its permissions shall be
50 * overwritten; if not, one shall be added.
51 */
52int
53acl_calc_mask(acl_t *acl_p)
54{
55	struct acl	*acl_int, *acl_int_new;
56	acl_t		acl_new;
57	size_t		i;
58	int		mask_mode, mask_num;
59
60	/*
61	 * (23.4.2.4) requires acl_p to point to a pointer to a valid ACL.
62	 * Since one of the primary reasons to use this function would be
63	 * to calculate the appropriate mask to obtain a valid ACL, we only
64	 * perform sanity checks here and validate the ACL prior to
65	 * returning.
66	 */
67	if (acl_p == NULL || *acl_p == NULL) {
68		errno = EINVAL;
69		return (-1);
70	}
71
72	if (!_acl_brand_may_be(*acl_p, ACL_BRAND_POSIX)) {
73		errno = EINVAL;
74		return (-1);
75	}
76	_acl_brand_as(*acl_p, ACL_BRAND_POSIX);
77
78	acl_int = &(*acl_p)->ats_acl;
79	if ((acl_int->acl_cnt < 3) || (acl_int->acl_cnt > ACL_MAX_ENTRIES)) {
80		errno = EINVAL;
81		return (-1);
82	}
83
84	acl_new = acl_dup(*acl_p);
85	if (acl_new == NULL)
86		return (-1);
87	acl_int_new = &acl_new->ats_acl;
88
89	mask_mode = 0;
90	mask_num = -1;
91
92	/* gather permissions and find a mask entry */
93	for (i = 0; i < acl_int_new->acl_cnt; i++) {
94		switch(acl_int_new->acl_entry[i].ae_tag) {
95		case ACL_USER:
96		case ACL_GROUP:
97		case ACL_GROUP_OBJ:
98			mask_mode |=
99			    acl_int_new->acl_entry[i].ae_perm & ACL_PERM_BITS;
100			break;
101		case ACL_MASK:
102			mask_num = (int)i;
103			break;
104		}
105	}
106
107	/* if a mask entry already exists, overwrite the perms */
108	if (mask_num != -1)
109		acl_int_new->acl_entry[mask_num].ae_perm = mask_mode;
110	else {
111		/* if no mask exists, check acl_cnt... */
112		if (acl_int_new->acl_cnt == ACL_MAX_ENTRIES) {
113			errno = ENOMEM;
114			acl_free(acl_new);
115			return (-1);
116		}
117		/* ...and add the mask entry */
118		acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_tag = ACL_MASK;
119		acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_id =
120		    ACL_UNDEFINED_ID;
121		acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_perm =
122		    mask_mode;
123		acl_int_new->acl_cnt++;
124	}
125
126	if (acl_valid(acl_new) == -1) {
127		errno = EINVAL;
128		acl_free(acl_new);
129		return (-1);
130	}
131
132	**acl_p = *acl_new;
133	acl_free(acl_new);
134
135	return (0);
136}
137