xref: /openbmc/linux/fs/jffs2/acl.c (revision 96de0e252cedffad61b3cb5e05662c591898e69a) 
1 /*
2  * JFFS2 -- Journalling Flash File System, Version 2.
3  *
4  * Copyright © 2006  NEC Corporation
5  *
6  * Created by KaiGai Kohei <kaigai@ak.jp.nec.com>
7  *
8  * For licensing information, see the file 'LICENCE' in this directory.
9  *
10  */
11 
12 #include <linux/kernel.h>
13 #include <linux/slab.h>
14 #include <linux/fs.h>
15 #include <linux/sched.h>
16 #include <linux/time.h>
17 #include <linux/crc32.h>
18 #include <linux/jffs2.h>
19 #include <linux/xattr.h>
20 #include <linux/posix_acl_xattr.h>
21 #include <linux/mtd/mtd.h>
22 #include "nodelist.h"
23 
24 static size_t jffs2_acl_size(int count)
25 {
26 	if (count <= 4) {
27 		return sizeof(struct jffs2_acl_header)
28 		       + count * sizeof(struct jffs2_acl_entry_short);
29 	} else {
30 		return sizeof(struct jffs2_acl_header)
31 		       + 4 * sizeof(struct jffs2_acl_entry_short)
32 		       + (count - 4) * sizeof(struct jffs2_acl_entry);
33 	}
34 }
35 
36 static int jffs2_acl_count(size_t size)
37 {
38 	size_t s;
39 
40 	size -= sizeof(struct jffs2_acl_header);
41 	s = size - 4 * sizeof(struct jffs2_acl_entry_short);
42 	if (s < 0) {
43 		if (size % sizeof(struct jffs2_acl_entry_short))
44 			return -1;
45 		return size / sizeof(struct jffs2_acl_entry_short);
46 	} else {
47 		if (s % sizeof(struct jffs2_acl_entry))
48 			return -1;
49 		return s / sizeof(struct jffs2_acl_entry) + 4;
50 	}
51 }
52 
53 static struct posix_acl *jffs2_acl_from_medium(void *value, size_t size)
54 {
55 	void *end = value + size;
56 	struct jffs2_acl_header *header = value;
57 	struct jffs2_acl_entry *entry;
58 	struct posix_acl *acl;
59 	uint32_t ver;
60 	int i, count;
61 
62 	if (!value)
63 		return NULL;
64 	if (size < sizeof(struct jffs2_acl_header))
65 		return ERR_PTR(-EINVAL);
66 	ver = je32_to_cpu(header->a_version);
67 	if (ver != JFFS2_ACL_VERSION) {
68 		JFFS2_WARNING("Invalid ACL version. (=%u)\n", ver);
69 		return ERR_PTR(-EINVAL);
70 	}
71 
72 	value += sizeof(struct jffs2_acl_header);
73 	count = jffs2_acl_count(size);
74 	if (count < 0)
75 		return ERR_PTR(-EINVAL);
76 	if (count == 0)
77 		return NULL;
78 
79 	acl = posix_acl_alloc(count, GFP_KERNEL);
80 	if (!acl)
81 		return ERR_PTR(-ENOMEM);
82 
83 	for (i=0; i < count; i++) {
84 		entry = value;
85 		if (value + sizeof(struct jffs2_acl_entry_short) > end)
86 			goto fail;
87 		acl->a_entries[i].e_tag = je16_to_cpu(entry->e_tag);
88 		acl->a_entries[i].e_perm = je16_to_cpu(entry->e_perm);
89 		switch (acl->a_entries[i].e_tag) {
90 			case ACL_USER_OBJ:
91 			case ACL_GROUP_OBJ:
92 			case ACL_MASK:
93 			case ACL_OTHER:
94 				value += sizeof(struct jffs2_acl_entry_short);
95 				acl->a_entries[i].e_id = ACL_UNDEFINED_ID;
96 				break;
97 
98 			case ACL_USER:
99 			case ACL_GROUP:
100 				value += sizeof(struct jffs2_acl_entry);
101 				if (value > end)
102 					goto fail;
103 				acl->a_entries[i].e_id = je32_to_cpu(entry->e_id);
104 				break;
105 
106 			default:
107 				goto fail;
108 		}
109 	}
110 	if (value != end)
111 		goto fail;
112 	return acl;
113  fail:
114 	posix_acl_release(acl);
115 	return ERR_PTR(-EINVAL);
116 }
117 
118 static void *jffs2_acl_to_medium(const struct posix_acl *acl, size_t *size)
119 {
120 	struct jffs2_acl_header *header;
121 	struct jffs2_acl_entry *entry;
122 	void *e;
123 	size_t i;
124 
125 	*size = jffs2_acl_size(acl->a_count);
126 	header = kmalloc(sizeof(*header) + acl->a_count * sizeof(*entry), GFP_KERNEL);
127 	if (!header)
128 		return ERR_PTR(-ENOMEM);
129 	header->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
130 	e = header + 1;
131 	for (i=0; i < acl->a_count; i++) {
132 		entry = e;
133 		entry->e_tag = cpu_to_je16(acl->a_entries[i].e_tag);
134 		entry->e_perm = cpu_to_je16(acl->a_entries[i].e_perm);
135 		switch(acl->a_entries[i].e_tag) {
136 			case ACL_USER:
137 			case ACL_GROUP:
138 				entry->e_id = cpu_to_je32(acl->a_entries[i].e_id);
139 				e += sizeof(struct jffs2_acl_entry);
140 				break;
141 
142 			case ACL_USER_OBJ:
143 			case ACL_GROUP_OBJ:
144 			case ACL_MASK:
145 			case ACL_OTHER:
146 				e += sizeof(struct jffs2_acl_entry_short);
147 				break;
148 
149 			default:
150 				goto fail;
151 		}
152 	}
153 	return header;
154  fail:
155 	kfree(header);
156 	return ERR_PTR(-EINVAL);
157 }
158 
159 static struct posix_acl *jffs2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
160 {
161 	struct posix_acl *acl = JFFS2_ACL_NOT_CACHED;
162 
163 	spin_lock(&inode->i_lock);
164 	if (*i_acl != JFFS2_ACL_NOT_CACHED)
165 		acl = posix_acl_dup(*i_acl);
166 	spin_unlock(&inode->i_lock);
167 	return acl;
168 }
169 
170 static void jffs2_iset_acl(struct inode *inode, struct posix_acl **i_acl, struct posix_acl *acl)
171 {
172 	spin_lock(&inode->i_lock);
173 	if (*i_acl != JFFS2_ACL_NOT_CACHED)
174 		posix_acl_release(*i_acl);
175 	*i_acl = posix_acl_dup(acl);
176 	spin_unlock(&inode->i_lock);
177 }
178 
179 struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
180 {
181 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
182 	struct posix_acl *acl;
183 	char *value = NULL;
184 	int rc, xprefix;
185 
186 	switch (type) {
187 	case ACL_TYPE_ACCESS:
188 		acl = jffs2_iget_acl(inode, &f->i_acl_access);
189 		if (acl != JFFS2_ACL_NOT_CACHED)
190 			return acl;
191 		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
192 		break;
193 	case ACL_TYPE_DEFAULT:
194 		acl = jffs2_iget_acl(inode, &f->i_acl_default);
195 		if (acl != JFFS2_ACL_NOT_CACHED)
196 			return acl;
197 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
198 		break;
199 	default:
200 		return ERR_PTR(-EINVAL);
201 	}
202 	rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
203 	if (rc > 0) {
204 		value = kmalloc(rc, GFP_KERNEL);
205 		if (!value)
206 			return ERR_PTR(-ENOMEM);
207 		rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
208 	}
209 	if (rc > 0) {
210 		acl = jffs2_acl_from_medium(value, rc);
211 	} else if (rc == -ENODATA || rc == -ENOSYS) {
212 		acl = NULL;
213 	} else {
214 		acl = ERR_PTR(rc);
215 	}
216 	if (value)
217 		kfree(value);
218 	if (!IS_ERR(acl)) {
219 		switch (type) {
220 		case ACL_TYPE_ACCESS:
221 			jffs2_iset_acl(inode, &f->i_acl_access, acl);
222 			break;
223 		case ACL_TYPE_DEFAULT:
224 			jffs2_iset_acl(inode, &f->i_acl_default, acl);
225 			break;
226 		}
227 	}
228 	return acl;
229 }
230 
231 static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
232 {
233 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
234 	size_t size = 0;
235 	char *value = NULL;
236 	int rc, xprefix;
237 
238 	if (S_ISLNK(inode->i_mode))
239 		return -EOPNOTSUPP;
240 
241 	switch (type) {
242 	case ACL_TYPE_ACCESS:
243 		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
244 		if (acl) {
245 			mode_t mode = inode->i_mode;
246 			rc = posix_acl_equiv_mode(acl, &mode);
247 			if (rc < 0)
248 				return rc;
249 			if (inode->i_mode != mode) {
250 				struct iattr attr;
251 
252 				attr.ia_valid = ATTR_MODE;
253 				attr.ia_mode = mode;
254 				rc = jffs2_do_setattr(inode, &attr);
255 				if (rc < 0)
256 					return rc;
257 			}
258 			if (rc == 0)
259 				acl = NULL;
260 		}
261 		break;
262 	case ACL_TYPE_DEFAULT:
263 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
264 		if (!S_ISDIR(inode->i_mode))
265 			return acl ? -EACCES : 0;
266 		break;
267 	default:
268 		return -EINVAL;
269 	}
270 	if (acl) {
271 		value = jffs2_acl_to_medium(acl, &size);
272 		if (IS_ERR(value))
273 			return PTR_ERR(value);
274 	}
275 
276 	rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
277 	if (!value && rc == -ENODATA)
278 		rc = 0;
279 	if (value)
280 		kfree(value);
281 	if (!rc) {
282 		switch(type) {
283 		case ACL_TYPE_ACCESS:
284 			jffs2_iset_acl(inode, &f->i_acl_access, acl);
285 			break;
286 		case ACL_TYPE_DEFAULT:
287 			jffs2_iset_acl(inode, &f->i_acl_default, acl);
288 			break;
289 		}
290 	}
291 	return rc;
292 }
293 
294 static int jffs2_check_acl(struct inode *inode, int mask)
295 {
296 	struct posix_acl *acl;
297 	int rc;
298 
299 	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
300 	if (IS_ERR(acl))
301 		return PTR_ERR(acl);
302 	if (acl) {
303 		rc = posix_acl_permission(inode, acl, mask);
304 		posix_acl_release(acl);
305 		return rc;
306 	}
307 	return -EAGAIN;
308 }
309 
310 int jffs2_permission(struct inode *inode, int mask, struct nameidata *nd)
311 {
312 	return generic_permission(inode, mask, jffs2_check_acl);
313 }
314 
315 int jffs2_init_acl(struct inode *inode, struct posix_acl *acl)
316 {
317 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
318 	struct posix_acl *clone;
319 	mode_t mode;
320 	int rc = 0;
321 
322 	f->i_acl_access = JFFS2_ACL_NOT_CACHED;
323 	f->i_acl_default = JFFS2_ACL_NOT_CACHED;
324 
325 	if (acl) {
326 		if (S_ISDIR(inode->i_mode)) {
327 			rc = jffs2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
328 			if (rc)
329 				goto cleanup;
330 		}
331 		clone = posix_acl_clone(acl, GFP_KERNEL);
332 		rc = -ENOMEM;
333 		if (!clone)
334 			goto cleanup;
335 		mode = inode->i_mode;
336 		rc = posix_acl_create_masq(clone, &mode);
337 		if (rc >= 0) {
338 			inode->i_mode = mode;
339 			if (rc > 0)
340 				rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
341 		}
342 		posix_acl_release(clone);
343 	}
344  cleanup:
345 	posix_acl_release(acl);
346 	return rc;
347 }
348 
349 void jffs2_clear_acl(struct jffs2_inode_info *f)
350 {
351 	if (f->i_acl_access && f->i_acl_access != JFFS2_ACL_NOT_CACHED) {
352 		posix_acl_release(f->i_acl_access);
353 		f->i_acl_access = JFFS2_ACL_NOT_CACHED;
354 	}
355 	if (f->i_acl_default && f->i_acl_default != JFFS2_ACL_NOT_CACHED) {
356 		posix_acl_release(f->i_acl_default);
357 		f->i_acl_default = JFFS2_ACL_NOT_CACHED;
358 	}
359 }
360 
361 int jffs2_acl_chmod(struct inode *inode)
362 {
363 	struct posix_acl *acl, *clone;
364 	int rc;
365 
366 	if (S_ISLNK(inode->i_mode))
367 		return -EOPNOTSUPP;
368 	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
369 	if (IS_ERR(acl) || !acl)
370 		return PTR_ERR(acl);
371 	clone = posix_acl_clone(acl, GFP_KERNEL);
372 	posix_acl_release(acl);
373 	if (!clone)
374 		return -ENOMEM;
375 	rc = posix_acl_chmod_masq(clone, inode->i_mode);
376 	if (!rc)
377 		rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
378 	posix_acl_release(clone);
379 	return rc;
380 }
381 
382 static size_t jffs2_acl_access_listxattr(struct inode *inode, char *list, size_t list_size,
383 					 const char *name, size_t name_len)
384 {
385 	const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
386 
387 	if (list && retlen <= list_size)
388 		strcpy(list, POSIX_ACL_XATTR_ACCESS);
389 	return retlen;
390 }
391 
392 static size_t jffs2_acl_default_listxattr(struct inode *inode, char *list, size_t list_size,
393 					  const char *name, size_t name_len)
394 {
395 	const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
396 
397 	if (list && retlen <= list_size)
398 		strcpy(list, POSIX_ACL_XATTR_DEFAULT);
399 	return retlen;
400 }
401 
402 static int jffs2_acl_getxattr(struct inode *inode, int type, void *buffer, size_t size)
403 {
404 	struct posix_acl *acl;
405 	int rc;
406 
407 	acl = jffs2_get_acl(inode, type);
408 	if (IS_ERR(acl))
409 		return PTR_ERR(acl);
410 	if (!acl)
411 		return -ENODATA;
412 	rc = posix_acl_to_xattr(acl, buffer, size);
413 	posix_acl_release(acl);
414 
415 	return rc;
416 }
417 
418 static int jffs2_acl_access_getxattr(struct inode *inode, const char *name, void *buffer, size_t size)
419 {
420 	if (name[0] != '\0')
421 		return -EINVAL;
422 	return jffs2_acl_getxattr(inode, ACL_TYPE_ACCESS, buffer, size);
423 }
424 
425 static int jffs2_acl_default_getxattr(struct inode *inode, const char *name, void *buffer, size_t size)
426 {
427 	if (name[0] != '\0')
428 		return -EINVAL;
429 	return jffs2_acl_getxattr(inode, ACL_TYPE_DEFAULT, buffer, size);
430 }
431 
432 static int jffs2_acl_setxattr(struct inode *inode, int type, const void *value, size_t size)
433 {
434 	struct posix_acl *acl;
435 	int rc;
436 
437 	if (!is_owner_or_cap(inode))
438 		return -EPERM;
439 
440 	if (value) {
441 		acl = posix_acl_from_xattr(value, size);
442 		if (IS_ERR(acl))
443 			return PTR_ERR(acl);
444 		if (acl) {
445 			rc = posix_acl_valid(acl);
446 			if (rc)
447 				goto out;
448 		}
449 	} else {
450 		acl = NULL;
451 	}
452 	rc = jffs2_set_acl(inode, type, acl);
453  out:
454 	posix_acl_release(acl);
455 	return rc;
456 }
457 
458 static int jffs2_acl_access_setxattr(struct inode *inode, const char *name,
459 				     const void *buffer, size_t size, int flags)
460 {
461 	if (name[0] != '\0')
462 		return -EINVAL;
463 	return jffs2_acl_setxattr(inode, ACL_TYPE_ACCESS, buffer, size);
464 }
465 
466 static int jffs2_acl_default_setxattr(struct inode *inode, const char *name,
467 				      const void *buffer, size_t size, int flags)
468 {
469 	if (name[0] != '\0')
470 		return -EINVAL;
471 	return jffs2_acl_setxattr(inode, ACL_TYPE_DEFAULT, buffer, size);
472 }
473 
474 struct xattr_handler jffs2_acl_access_xattr_handler = {
475 	.prefix	= POSIX_ACL_XATTR_ACCESS,
476 	.list	= jffs2_acl_access_listxattr,
477 	.get	= jffs2_acl_access_getxattr,
478 	.set	= jffs2_acl_access_setxattr,
479 };
480 
481 struct xattr_handler jffs2_acl_default_xattr_handler = {
482 	.prefix	= POSIX_ACL_XATTR_DEFAULT,
483 	.list	= jffs2_acl_default_listxattr,
484 	.get	= jffs2_acl_default_getxattr,
485 	.set	= jffs2_acl_default_setxattr,
486 };
487