acl_calc_mask.c revision 92986 
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 THE AUTHOR OR THE VOICES IN HIS HEAD BE
18 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
19 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
20 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
21 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
22 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
23 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
24 * POSSIBILITY OF SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/lib/libc/posix1e/acl_calc_mask.c 92986 2002-03-22 21:53:29Z obrien $");
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/*
39 * acl_calc_mask() (23.4.2): calculate and set the permissions
40 * associated with the ACL_MASK ACL entry.  If the ACL already
41 * contains an ACL_MASK entry, its permissions shall be
42 * overwritten; if not, one shall be added.
43 */
44int
45acl_calc_mask(acl_t *acl_p)
46{
47	struct acl	*acl_int, *acl_int_new;
48	acl_t		acl_new;
49	int		i, mask_mode, mask_num;
50
51	/*
52	 * (23.4.2.4) requires acl_p to point to a pointer to a valid ACL.
53	 * Since one of the primary reasons to use this function would be
54	 * to calculate the appropriate mask to obtain a valid ACL, we only
55	 * perform sanity checks here and validate the ACL prior to
56	 * returning.
57	 */
58	if (acl_p == NULL || *acl_p == NULL) {
59		errno = EINVAL;
60		return (-1);
61	}
62	acl_int = &(*acl_p)->ats_acl;
63	if ((acl_int->acl_cnt < 3) || (acl_int->acl_cnt > ACL_MAX_ENTRIES)) {
64		errno = EINVAL;
65		return (-1);
66	}
67
68	acl_new = acl_dup(*acl_p);
69	if (acl_new == NULL)
70		return (-1);
71	acl_int_new = &acl_new->ats_acl;
72
73	mask_mode = 0;
74	mask_num = -1;
75
76	/* gather permissions and find a mask entry */
77	for (i = 0; i < acl_int_new->acl_cnt; i++) {
78		switch(acl_int_new->acl_entry[i].ae_tag) {
79		case ACL_USER:
80		case ACL_GROUP:
81		case ACL_GROUP_OBJ:
82			mask_mode |=
83			    acl_int_new->acl_entry[i].ae_perm & ACL_PERM_BITS;
84			break;
85		case ACL_MASK:
86			mask_num = i;
87			break;
88		}
89	}
90
91	/* if a mask entry already exists, overwrite the perms */
92	if (mask_num != -1)
93		acl_int_new->acl_entry[mask_num].ae_perm = mask_mode;
94	else {
95		/* if no mask exists, check acl_cnt... */
96		if (acl_int_new->acl_cnt == ACL_MAX_ENTRIES) {
97			errno = ENOMEM;
98			return (-1);
99		}
100		/* ...and add the mask entry */
101		acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_tag = ACL_MASK;
102		acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_id =
103		    ACL_UNDEFINED_ID;
104		acl_int_new->acl_entry[acl_int_new->acl_cnt].ae_perm =
105		    mask_mode;
106		acl_int_new->acl_cnt++;
107	}
108
109	if (acl_valid(acl_new) == -1) {
110		errno = EINVAL;
111		acl_free(acl_new);
112		return (-1);
113	}
114
115	**acl_p = *acl_new;
116	acl_free(acl_new);
117
118	return (0);
119}
120