1 /*-
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 1999-2001, 2008 Robert N. M. Watson
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 THE 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 * Support functionality for the POSIX.1e ACL interface
30 * These calls are intended only to be called within the library.
31 */
32
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD: stable/12/lib/libc/posix1e/acl_support.c 326193 2017-11-25 17:12:48Z pfg $");
35
36 #include <sys/types.h>
37 #include "namespace.h"
38 #include <sys/acl.h>
39 #include "un-namespace.h"
40 #include <errno.h>
41 #include <grp.h>
42 #include <pwd.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 #include <assert.h>
47
48 #include "acl_support.h"
49
50 #define ACL_STRING_PERM_WRITE 'w'
51 #define ACL_STRING_PERM_READ 'r'
52 #define ACL_STRING_PERM_EXEC 'x'
53 #define ACL_STRING_PERM_NONE '-'
54
55 /*
56 * Return 0, if both ACLs are identical.
57 */
58 int
_acl_differs(const acl_t a,const acl_t b)59 _acl_differs(const acl_t a, const acl_t b)
60 {
61 int i;
62 struct acl_entry *entrya, *entryb;
63
64 assert(_acl_brand(a) == _acl_brand(b));
65 assert(_acl_brand(a) != ACL_BRAND_UNKNOWN);
66 assert(_acl_brand(b) != ACL_BRAND_UNKNOWN);
67
68 if (a->ats_acl.acl_cnt != b->ats_acl.acl_cnt)
69 return (1);
70
71 for (i = 0; i < b->ats_acl.acl_cnt; i++) {
72 entrya = &(a->ats_acl.acl_entry[i]);
73 entryb = &(b->ats_acl.acl_entry[i]);
74
75 if (entrya->ae_tag != entryb->ae_tag ||
76 entrya->ae_id != entryb->ae_id ||
77 entrya->ae_perm != entryb->ae_perm ||
78 entrya->ae_entry_type != entryb->ae_entry_type ||
79 entrya->ae_flags != entryb->ae_flags)
80 return (1);
81 }
82
83 return (0);
84 }
85
86 /*
87 * _posix1e_acl_entry_compare -- compare two acl_entry structures to
88 * determine the order they should appear in. Used by _posix1e_acl_sort to
89 * sort ACL entries into the kernel-desired order -- i.e., the order useful
90 * for evaluation and O(n) validity checking. Beter to have an O(nlogn) sort
91 * in userland and an O(n) in kernel than to have both in kernel.
92 */
93 typedef int (*compare)(const void *, const void *);
94 static int
_posix1e_acl_entry_compare(struct acl_entry * a,struct acl_entry * b)95 _posix1e_acl_entry_compare(struct acl_entry *a, struct acl_entry *b)
96 {
97
98 assert(_entry_brand(a) == ACL_BRAND_POSIX);
99 assert(_entry_brand(b) == ACL_BRAND_POSIX);
100
101 /*
102 * First, sort between tags -- conveniently defined in the correct
103 * order for verification.
104 */
105 if (a->ae_tag < b->ae_tag)
106 return (-1);
107 if (a->ae_tag > b->ae_tag)
108 return (1);
109
110 /*
111 * Next compare uids/gids on appropriate types.
112 */
113
114 if (a->ae_tag == ACL_USER || a->ae_tag == ACL_GROUP) {
115 if (a->ae_id < b->ae_id)
116 return (-1);
117 if (a->ae_id > b->ae_id)
118 return (1);
119
120 /* shouldn't be equal, fall through to the invalid case */
121 }
122
123 /*
124 * Don't know how to sort multiple entries of the rest--either it's
125 * a bad entry, or there shouldn't be more than one. Ignore and the
126 * validity checker can get it later.
127 */
128 return (0);
129 }
130
131 /*
132 * _posix1e_acl_sort -- sort ACL entries in POSIX.1e-formatted ACLs.
133 */
134 void
_posix1e_acl_sort(acl_t acl)135 _posix1e_acl_sort(acl_t acl)
136 {
137 struct acl *acl_int;
138
139 acl_int = &acl->ats_acl;
140
141 qsort(&acl_int->acl_entry[0], acl_int->acl_cnt,
142 sizeof(struct acl_entry), (compare) _posix1e_acl_entry_compare);
143 }
144
145 /*
146 * acl_posix1e -- in what situations should we acl_sort before submission?
147 * We apply posix1e ACL semantics for any ACL of type ACL_TYPE_ACCESS or
148 * ACL_TYPE_DEFAULT
149 */
150 int
_posix1e_acl(acl_t acl,acl_type_t type)151 _posix1e_acl(acl_t acl, acl_type_t type)
152 {
153
154 if (_acl_brand(acl) != ACL_BRAND_POSIX)
155 return (0);
156
157 return ((type == ACL_TYPE_ACCESS) || (type == ACL_TYPE_DEFAULT));
158 }
159
160 /*
161 * _posix1e_acl_check -- given an ACL, check its validity. This is mirrored
162 * from code in sys/kern/kern_acl.c, and if changes are made in one, they
163 * should be made in the other also. This copy of acl_check is made
164 * available * in userland for the benefit of processes wanting to check ACLs
165 * for validity before submitting them to the kernel, or for performing
166 * in userland file system checking. Needless to say, the kernel makes
167 * the real checks on calls to get/setacl.
168 *
169 * See the comments in kernel for explanation -- just briefly, it assumes
170 * an already sorted ACL, and checks based on that assumption. The
171 * POSIX.1e interface, acl_valid(), will perform the sort before calling
172 * this. Returns 0 on success, EINVAL on failure.
173 */
174 int
_posix1e_acl_check(acl_t acl)175 _posix1e_acl_check(acl_t acl)
176 {
177 struct acl *acl_int;
178 struct acl_entry *entry; /* current entry */
179 uid_t highest_uid=0, highest_gid=0;
180 int stage = ACL_USER_OBJ;
181 int i = 0;
182 int count_user_obj=0, count_user=0, count_group_obj=0,
183 count_group=0, count_mask=0, count_other=0;
184
185 acl_int = &acl->ats_acl;
186
187 /* printf("_posix1e_acl_check: checking acl with %d entries\n",
188 acl->acl_cnt); */
189 while (i < acl_int->acl_cnt) {
190 entry = &acl_int->acl_entry[i];
191
192 if ((entry->ae_perm | ACL_PERM_BITS) != ACL_PERM_BITS)
193 return (EINVAL);
194
195 switch(entry->ae_tag) {
196 case ACL_USER_OBJ:
197 /* printf("_posix1e_acl_check: %d: ACL_USER_OBJ\n",
198 i); */
199 if (stage > ACL_USER_OBJ)
200 return (EINVAL);
201 stage = ACL_USER;
202 count_user_obj++;
203 break;
204
205 case ACL_USER:
206 /* printf("_posix1e_acl_check: %d: ACL_USER\n", i); */
207 if (stage > ACL_USER)
208 return (EINVAL);
209 stage = ACL_USER;
210 if (count_user && (entry->ae_id <= highest_uid))
211 return (EINVAL);
212 highest_uid = entry->ae_id;
213 count_user++;
214 break;
215
216 case ACL_GROUP_OBJ:
217 /* printf("_posix1e_acl_check: %d: ACL_GROUP_OBJ\n",
218 i); */
219 if (stage > ACL_GROUP_OBJ)
220 return (EINVAL);
221 stage = ACL_GROUP;
222 count_group_obj++;
223 break;
224
225 case ACL_GROUP:
226 /* printf("_posix1e_acl_check: %d: ACL_GROUP\n", i); */
227 if (stage > ACL_GROUP)
228 return (EINVAL);
229 stage = ACL_GROUP;
230 if (count_group && (entry->ae_id <= highest_gid))
231 return (EINVAL);
232 highest_gid = entry->ae_id;
233 count_group++;
234 break;
235
236 case ACL_MASK:
237 /* printf("_posix1e_acl_check: %d: ACL_MASK\n", i); */
238 if (stage > ACL_MASK)
239 return (EINVAL);
240 stage = ACL_MASK;
241 count_mask++;
242 break;
243
244 case ACL_OTHER:
245 /* printf("_posix1e_acl_check: %d: ACL_OTHER\n", i); */
246 if (stage > ACL_OTHER)
247 return (EINVAL);
248 stage = ACL_OTHER;
249 count_other++;
250 break;
251
252 default:
253 /* printf("_posix1e_acl_check: %d: INVALID\n", i); */
254 return (EINVAL);
255 }
256 i++;
257 }
258
259 if (count_user_obj != 1)
260 return (EINVAL);
261
262 if (count_group_obj != 1)
263 return (EINVAL);
264
265 if (count_mask != 0 && count_mask != 1)
266 return (EINVAL);
267
268 if (count_other != 1)
269 return (EINVAL);
270
271 return (0);
272 }
273
274 /*
275 * Given a right-shifted permission (i.e., direct ACL_PERM_* mask), fill
276 * in a string describing the permissions.
277 */
278 int
_posix1e_acl_perm_to_string(acl_perm_t perm,ssize_t buf_len,char * buf)279 _posix1e_acl_perm_to_string(acl_perm_t perm, ssize_t buf_len, char *buf)
280 {
281
282 if (buf_len < _POSIX1E_ACL_STRING_PERM_MAXSIZE + 1) {
283 errno = ENOMEM;
284 return (-1);
285 }
286
287 if ((perm | ACL_PERM_BITS) != ACL_PERM_BITS) {
288 errno = EINVAL;
289 return (-1);
290 }
291
292 buf[3] = 0; /* null terminate */
293
294 if (perm & ACL_READ)
295 buf[0] = ACL_STRING_PERM_READ;
296 else
297 buf[0] = ACL_STRING_PERM_NONE;
298
299 if (perm & ACL_WRITE)
300 buf[1] = ACL_STRING_PERM_WRITE;
301 else
302 buf[1] = ACL_STRING_PERM_NONE;
303
304 if (perm & ACL_EXECUTE)
305 buf[2] = ACL_STRING_PERM_EXEC;
306 else
307 buf[2] = ACL_STRING_PERM_NONE;
308
309 return (0);
310 }
311
312 /*
313 * given a string, return a permission describing it
314 */
315 int
_posix1e_acl_string_to_perm(char * string,acl_perm_t * perm)316 _posix1e_acl_string_to_perm(char *string, acl_perm_t *perm)
317 {
318 acl_perm_t myperm = ACL_PERM_NONE;
319 char *ch;
320
321 ch = string;
322 while (*ch) {
323 switch(*ch) {
324 case ACL_STRING_PERM_READ:
325 myperm |= ACL_READ;
326 break;
327 case ACL_STRING_PERM_WRITE:
328 myperm |= ACL_WRITE;
329 break;
330 case ACL_STRING_PERM_EXEC:
331 myperm |= ACL_EXECUTE;
332 break;
333 case ACL_STRING_PERM_NONE:
334 break;
335 default:
336 return (EINVAL);
337 }
338 ch++;
339 }
340
341 *perm = myperm;
342 return (0);
343 }
344
345 /*
346 * Add an ACL entry without doing much checking, et al
347 */
348 int
_posix1e_acl_add_entry(acl_t acl,acl_tag_t tag,uid_t id,acl_perm_t perm)349 _posix1e_acl_add_entry(acl_t acl, acl_tag_t tag, uid_t id, acl_perm_t perm)
350 {
351 struct acl *acl_int;
352 struct acl_entry *e;
353
354 acl_int = &acl->ats_acl;
355
356 if (acl_int->acl_cnt >= ACL_MAX_ENTRIES) {
357 errno = ENOMEM;
358 return (-1);
359 }
360
361 e = &(acl_int->acl_entry[acl_int->acl_cnt]);
362 e->ae_perm = perm;
363 e->ae_tag = tag;
364 e->ae_id = id;
365 acl_int->acl_cnt++;
366
367 return (0);
368 }
369
370 /*
371 * Convert "old" type - ACL_TYPE_{ACCESS,DEFAULT}_OLD - into its "new"
372 * counterpart. It's necessary for the old (pre-NFSv4 ACLs) binaries
373 * to work with new libc and kernel. Fixing 'type' for old binaries with
374 * old libc and new kernel is being done by kern/vfs_acl.c:type_unold().
375 */
376 int
_acl_type_unold(acl_type_t type)377 _acl_type_unold(acl_type_t type)
378 {
379
380 switch (type) {
381 case ACL_TYPE_ACCESS_OLD:
382 return (ACL_TYPE_ACCESS);
383 case ACL_TYPE_DEFAULT_OLD:
384 return (ACL_TYPE_DEFAULT);
385 default:
386 return (type);
387 }
388 }
389
390 char *
string_skip_whitespace(char * string)391 string_skip_whitespace(char *string)
392 {
393
394 while (*string && ((*string == ' ') || (*string == '\t')))
395 string++;
396
397 return (string);
398 }
399
400 void
string_trim_trailing_whitespace(char * string)401 string_trim_trailing_whitespace(char *string)
402 {
403 char *end;
404
405 if (*string == '\0')
406 return;
407
408 end = string + strlen(string) - 1;
409
410 while (end != string) {
411 if ((*end == ' ') || (*end == '\t')) {
412 *end = '\0';
413 end--;
414 } else {
415 return;
416 }
417 }
418
419 return;
420 }
421