acl_calc_mask.c revision 194955 
1/*
2 * Copyright (c) 2001-2002 Chris D. Faulhaber
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/lib/libc/posix1e/acl_calc_mask.c 194955 2009-06-25 12:46:59Z trasz $");
29
30#include <sys/types.h>
31#include "namespace.h"
32#include <sys/acl.h>
33#include "un-namespace.h"
34
35#include <errno.h>
36#include <stdio.h>
37
38#include "acl_support.h"
39
40/*
41 * acl_calc_mask() (23.4.2): calculate and set the permissions
42 * associated with the ACL_MASK ACL entry.  If the ACL already
43 * contains an ACL_MASK entry, its permissions shall be
44 * overwritten; if not, one shall be added.
45 */
46int
47acl_calc_mask(acl_t *acl_p)
48{
49	struct acl	*acl_int, *acl_int_new;
50	acl_t		acl_new;
51	int		i, mask_mode, mask_num;
52
53	if (!_acl_brand_may_be(*acl_p, ACL_BRAND_POSIX)) {
54		errno = EINVAL;
55		return (-1);
56	}
57	_acl_brand_as(*acl_p, ACL_BRAND_POSIX);
58
59	/*
60	 * (23.4.2.4) requires acl_p to point to a pointer to a valid ACL.
61	 * Since one of the primary reasons to use this function would be
62	 * to calculate the appropriate mask to obtain a valid ACL, we only
63	 * perform sanity checks here and validate the ACL prior to
64	 * returning.
65	 */
66	if (acl_p == NULL || *acl_p == NULL) {
67		errno = EINVAL;
68		return (-1);
69	}
70	acl_int = &(*acl_p)->ats_acl;
71	if ((acl_int->acl_cnt < 3) || (acl_int->acl_cnt > ACL_MAX_ENTRIES)) {
72		errno = EINVAL;
73		return (-1);
74	}
75
76	acl_new = acl_dup(*acl_p);
77	if (acl_new == NULL)
78		return (-1);
79	acl_int_new = &acl_new->ats_acl;
80
81	mask_mode = 0;
82	mask_num = -1;
83
84	/* gather permissions and find a mask entry */
85	for (i = 0; i < acl_int_new->acl_cnt; i++) {
86		switch(acl_int_new->acl_entry[i].ae_tag) {
87		case ACL_USER:
88		case ACL_GROUP:
89		case ACL_GROUP_OBJ:
90			mask_mode |=
91			    acl_int_new->acl_entry[i].ae_perm & ACL_PERM_BITS;
92			break;
93		case ACL_MASK:
94			mask_num = i;
95			break;
96		}
97	}
98
99	/* if a mask entry already exists, overwrite the perms */
100	if (mask_num != -1)
101		acl_int_new->acl_entry[mask_num].ae_perm = mask_mode;
102	else {
103		/* if no mask exists, check acl_cnt... */
104		if (acl_int_new->acl_cnt == ACL_MAX_ENTRIES) {
105			errno = ENOMEM;
106			return (-1);
107		}
108		/* ...and add the mask entry */
109		acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_tag = ACL_MASK;
110		acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_id =
111		    ACL_UNDEFINED_ID;
112		acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_perm =
113		    mask_mode;
114		acl_int_new->acl_cnt++;
115	}
116
117	if (acl_valid(acl_new) == -1) {
118		errno = EINVAL;
119		acl_free(acl_new);
120		return (-1);
121	}
122
123	**acl_p = *acl_new;
124	acl_free(acl_new);
125
126	return (0);
127}
128