xref: /freebsd/lib/libc/posix1e/acl_strip.c (revision 11b249f99e4d4891bd2a21ef796d40073ee15508)
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 		acl_free(acl_old);
87 		return (NULL);
88 	}
89 	tag = ACL_UNDEFINED_TAG;
90 
91 	/* only save the default user/group/other entries */
92 	entry_id = ACL_FIRST_ENTRY;
93 	while (acl_get_entry(acl_old, entry_id, &entry) == 1) {
94 		entry_id = ACL_NEXT_ENTRY;
95 
96 		assert(_entry_brand(entry) == ACL_BRAND_POSIX);
97 
98 		if (acl_get_tag_type(entry, &tag) == -1)
99 			goto fail;
100 
101 		switch(tag) {
102 		case ACL_USER_OBJ:
103 		case ACL_GROUP_OBJ:
104 		case ACL_OTHER:
105 			if (acl_get_tag_type(entry, &tag) == -1)
106 				goto fail;
107 			if (acl_get_permset(entry, &perm) == -1)
108 				goto fail;
109 			if (acl_create_entry(&acl_new, &entry_new) == -1)
110 				goto fail;
111 			if (acl_set_tag_type(entry_new, tag) == -1)
112 				goto fail;
113 			if (acl_set_permset(entry_new, perm) == -1)
114 				goto fail;
115 			if (acl_copy_entry(entry_new, entry) == -1)
116 				goto fail;
117 			assert(_entry_brand(entry_new) == ACL_BRAND_POSIX);
118 			break;
119 		case ACL_MASK:
120 			have_mask_entry = 1;
121 			break;
122 		default:
123 			break;
124 		}
125 	}
126 
127 	assert(_acl_brand(acl_new) == ACL_BRAND_POSIX);
128 
129 	if (have_mask_entry && recalculate_mask) {
130 		if (acl_calc_mask(&acl_new) == -1)
131 			goto fail;
132 	}
133 
134 	return (acl_new);
135 
136 fail:
137 	acl_free(acl_new);
138 	acl_free(acl_old);
139 
140 	return (NULL);
141 }
142 
143 acl_t
144 acl_strip_np(const acl_t aclp, int recalculate_mask)
145 {
146 	switch (_acl_brand(aclp)) {
147 	case ACL_BRAND_NFS4:
148 		return (_nfs4_acl_strip_np(aclp, 0));
149 
150 	case ACL_BRAND_POSIX:
151 		return (_posix1e_acl_strip_np(aclp, recalculate_mask));
152 
153 	default:
154 		errno = EINVAL;
155 		return (NULL);
156 	}
157 }
158 
159 /*
160  * Return 1, if ACL is trivial, 0 otherwise.
161  *
162  * ACL is trivial, iff its meaning could be fully expressed using just file
163  * mode.  In other words, ACL is trivial iff it doesn't have "+" to the right
164  * of the mode bits in "ls -l" output ;-)
165  */
166 int
167 acl_is_trivial_np(const acl_t aclp, int *trivialp)
168 {
169 	acl_t tmpacl;
170 	int differs;
171 
172 	if (aclp == NULL || trivialp == NULL) {
173 		errno = EINVAL;
174 		return (-1);
175 	}
176 
177 	switch (_acl_brand(aclp)) {
178 	case ACL_BRAND_POSIX:
179 		if (aclp->ats_acl.acl_cnt == 3)
180 			*trivialp = 1;
181 		else
182 			*trivialp = 0;
183 
184 		return (0);
185 
186 	case ACL_BRAND_NFS4:
187 		/*
188 		 * If the ACL has more than canonical six entries,
189 		 * it's non trivial by definition.
190 		 */
191 		if (aclp->ats_acl.acl_cnt > 6) {
192 			*trivialp = 0;
193 			return (0);
194 		}
195 
196 		/*
197 		 * Calculate trivial ACL - using acl_strip_np(3) - and compare
198 		 * with the original.
199 		 */
200 		tmpacl = _nfs4_acl_strip_np(aclp, 0);
201 		if (tmpacl == NULL)
202 			return (-1);
203 
204 		differs = _acl_differs(aclp, tmpacl);
205 		acl_free(tmpacl);
206 
207 		if (differs == 0) {
208 			*trivialp = 1;
209 			return (0);
210 		}
211 
212 		/*
213 		 * Try again with an old-style, "canonical six" trivial ACL.
214 		 */
215 		tmpacl = _nfs4_acl_strip_np(aclp, 1);
216 		if (tmpacl == NULL)
217 			return (-1);
218 
219 		differs = _acl_differs(aclp, tmpacl);
220 		acl_free(tmpacl);
221 
222 		if (differs)
223 			*trivialp = 0;
224 		else
225 			*trivialp = 1;
226 
227 		return (0);
228 
229 	default:
230 		errno = EINVAL;
231 		return (-1);
232 	}
233 }
234