xref: /freebsd/lib/libc/posix1e/acl_strip.c (revision cdec38567415b1178351d90d2ad034f5186dbf00)
1 /*-
2  * Copyright (c) 2001 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 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("$FreeBSD$");
29 
30 #include <errno.h>
31 #include <stdio.h>
32 #include <assert.h>
33 #include <sys/acl.h>
34 #include <sys/stat.h>
35 
36 #include "acl_support.h"
37 
38 /*
39  * These routines from sys/kern/subr_acl_nfs4.c are used by both kernel
40  * and libc.
41  */
42 void	acl_nfs4_sync_mode_from_acl(mode_t *_mode, const struct acl *aclp);
43 void	acl_nfs4_trivial_from_mode_libc(struct acl *aclp, int file_owner_id,
44 	    int canonical_six);
45 
46 static acl_t
47 _nfs4_acl_strip_np(const acl_t aclp, int canonical_six)
48 {
49 	acl_t newacl;
50 	mode_t mode = 0;
51 
52 	newacl = acl_init(ACL_MAX_ENTRIES);
53 	if (newacl == NULL) {
54 		errno = ENOMEM;
55 		return (NULL);
56 	}
57 
58 	_acl_brand_as(newacl, ACL_BRAND_NFS4);
59 
60 	acl_nfs4_sync_mode_from_acl(&mode, &(aclp->ats_acl));
61 	acl_nfs4_trivial_from_mode_libc(&(newacl->ats_acl), mode, canonical_six);
62 
63 	return (newacl);
64 }
65 
66 static acl_t
67 _posix1e_acl_strip_np(const acl_t aclp, int recalculate_mask)
68 {
69 	acl_t acl_new, acl_old;
70 	acl_entry_t entry, entry_new;
71 	acl_permset_t perm;
72 	acl_tag_t tag;
73 	int entry_id, have_mask_entry;
74 
75 	assert(_acl_brand(aclp) == ACL_BRAND_POSIX);
76 
77 	acl_old = acl_dup(aclp);
78 	if (acl_old == NULL)
79 		return (NULL);
80 
81 	assert(_acl_brand(acl_old) == ACL_BRAND_POSIX);
82 
83 	have_mask_entry = 0;
84 	acl_new = acl_init(ACL_MAX_ENTRIES);
85 	if (acl_new == NULL)
86 		return (NULL);
87 	tag = ACL_UNDEFINED_TAG;
88 
89 	/* only save the default user/group/other entries */
90 	entry_id = ACL_FIRST_ENTRY;
91 	while (acl_get_entry(acl_old, entry_id, &entry) == 1) {
92 		entry_id = ACL_NEXT_ENTRY;
93 
94 		assert(_entry_brand(entry) == ACL_BRAND_POSIX);
95 
96 		if (acl_get_tag_type(entry, &tag) == -1)
97 			return (NULL);
98 
99 		switch(tag) {
100 		case ACL_USER_OBJ:
101 		case ACL_GROUP_OBJ:
102 		case ACL_OTHER:
103 			if (acl_get_tag_type(entry, &tag) == -1)
104 				return (NULL);
105 			if (acl_get_permset(entry, &perm) == -1)
106 				return (NULL);
107 			if (acl_create_entry(&acl_new, &entry_new) == -1)
108 				return (NULL);
109 			if (acl_set_tag_type(entry_new, tag) == -1)
110 				return (NULL);
111 			if (acl_set_permset(entry_new, perm) == -1)
112 				return (NULL);
113 			if (acl_copy_entry(entry_new, entry) == -1)
114 				return (NULL);
115 			assert(_entry_brand(entry_new) == ACL_BRAND_POSIX);
116 			break;
117 		case ACL_MASK:
118 			have_mask_entry = 1;
119 			break;
120 		default:
121 			break;
122 		}
123 	}
124 
125 	assert(_acl_brand(acl_new) == ACL_BRAND_POSIX);
126 
127 	if (have_mask_entry && recalculate_mask) {
128 		if (acl_calc_mask(&acl_new) == -1)
129 			return (NULL);
130 	}
131 
132 	return (acl_new);
133 }
134 
135 acl_t
136 acl_strip_np(const acl_t aclp, int recalculate_mask)
137 {
138 	switch (_acl_brand(aclp)) {
139 	case ACL_BRAND_NFS4:
140 		return (_nfs4_acl_strip_np(aclp, 0));
141 
142 	case ACL_BRAND_POSIX:
143 		return (_posix1e_acl_strip_np(aclp, recalculate_mask));
144 
145 	default:
146 		errno = EINVAL;
147 		return (NULL);
148 	}
149 }
150 
151 /*
152  * Return 1, if ACL is trivial, 0 otherwise.
153  *
154  * ACL is trivial, iff its meaning could be fully expressed using just file
155  * mode.  In other words, ACL is trivial iff it doesn't have "+" to the right
156  * of the mode bits in "ls -l" output ;-)
157  */
158 int
159 acl_is_trivial_np(const acl_t aclp, int *trivialp)
160 {
161 	acl_t tmpacl;
162 	int differs;
163 
164 	if (aclp == NULL || trivialp == NULL) {
165 		errno = EINVAL;
166 		return (-1);
167 	}
168 
169 	switch (_acl_brand(aclp)) {
170 	case ACL_BRAND_POSIX:
171 		if (aclp->ats_acl.acl_cnt == 3)
172 			*trivialp = 1;
173 		else
174 			*trivialp = 0;
175 
176 		return (0);
177 
178 	case ACL_BRAND_NFS4:
179 		/*
180 		 * If the ACL has more than canonical six entries,
181 		 * it's non trivial by definition.
182 		 */
183 		if (aclp->ats_acl.acl_cnt > 6) {
184 			*trivialp = 0;
185 			return (0);
186 		}
187 
188 		/*
189 		 * Calculate trivial ACL - using acl_strip_np(3) - and compare
190 		 * with the original.
191 		 */
192 		tmpacl = _nfs4_acl_strip_np(aclp, 0);
193 		if (tmpacl == NULL)
194 			return (-1);
195 
196 		differs = _acl_differs(aclp, tmpacl);
197 		acl_free(tmpacl);
198 
199 		if (differs == 0) {
200 			*trivialp = 1;
201 			return (0);
202 		}
203 
204 		/*
205 		 * Try again with an old-style, "canonical six" trivial ACL.
206 		 */
207 		tmpacl = _nfs4_acl_strip_np(aclp, 1);
208 		if (tmpacl == NULL)
209 			return (-1);
210 
211 		differs = _acl_differs(aclp, tmpacl);
212 		acl_free(tmpacl);
213 
214 		if (differs)
215 			*trivialp = 0;
216 		else
217 			*trivialp = 1;
218 
219 		return (0);
220 
221 	default:
222 		errno = EINVAL;
223 		return (-1);
224 	}
225 }
226