xref: /linux/fs/jffs2/acl.c (revision 5e8d780d745c1619aba81fe7166c5a4b5cad2b84) 
1 /*
2  * JFFS2 -- Journalling Flash File System, Version 2.
3  *
4  * Copyright (C) 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 #include <linux/kernel.h>
12 #include <linux/slab.h>
13 #include <linux/fs.h>
14 #include <linux/time.h>
15 #include <linux/crc32.h>
16 #include <linux/jffs2.h>
17 #include <linux/xattr.h>
18 #include <linux/posix_acl_xattr.h>
19 #include <linux/mtd/mtd.h>
20 #include "nodelist.h"
21 
22 static size_t jffs2_acl_size(int count)
23 {
24 	if (count <= 4) {
25 		return sizeof(struct jffs2_acl_header)
26 		       + count * sizeof(struct jffs2_acl_entry_short);
27 	} else {
28 		return sizeof(struct jffs2_acl_header)
29 		       + 4 * sizeof(struct jffs2_acl_entry_short)
30 		       + (count - 4) * sizeof(struct jffs2_acl_entry);
31 	}
32 }
33 
34 static int jffs2_acl_count(size_t size)
35 {
36 	size_t s;
37 
38 	size -= sizeof(struct jffs2_acl_header);
39 	s = size - 4 * sizeof(struct jffs2_acl_entry_short);
40 	if (s < 0) {
41 		if (size % sizeof(struct jffs2_acl_entry_short))
42 			return -1;
43 		return size / sizeof(struct jffs2_acl_entry_short);
44 	} else {
45 		if (s % sizeof(struct jffs2_acl_entry))
46 			return -1;
47 		return s / sizeof(struct jffs2_acl_entry) + 4;
48 	}
49 }
50 
51 static struct posix_acl *jffs2_acl_from_medium(void *value, size_t size)
52 {
53 	void *end = value + size;
54 	struct jffs2_acl_header *header = value;
55 	struct jffs2_acl_entry *entry;
56 	struct posix_acl *acl;
57 	uint32_t ver;
58 	int i, count;
59 
60 	if (!value)
61 		return NULL;
62 	if (size < sizeof(struct jffs2_acl_header))
63 		return ERR_PTR(-EINVAL);
64 	ver = je32_to_cpu(header->a_version);
65 	if (ver != JFFS2_ACL_VERSION) {
66 		JFFS2_WARNING("Invalid ACL version. (=%u)\n", ver);
67 		return ERR_PTR(-EINVAL);
68 	}
69 
70 	value += sizeof(struct jffs2_acl_header);
71 	count = jffs2_acl_count(size);
72 	if (count < 0)
73 		return ERR_PTR(-EINVAL);
74 	if (count == 0)
75 		return NULL;
76 
77 	acl = posix_acl_alloc(count, GFP_KERNEL);
78 	if (!acl)
79 		return ERR_PTR(-ENOMEM);
80 
81 	for (i=0; i < count; i++) {
82 		entry = value;
83 		if (value + sizeof(struct jffs2_acl_entry_short) > end)
84 			goto fail;
85 		acl->a_entries[i].e_tag = je16_to_cpu(entry->e_tag);
86 		acl->a_entries[i].e_perm = je16_to_cpu(entry->e_perm);
87 		switch (acl->a_entries[i].e_tag) {
88 			case ACL_USER_OBJ:
89 			case ACL_GROUP_OBJ:
90 			case ACL_MASK:
91 			case ACL_OTHER:
92 				value += sizeof(struct jffs2_acl_entry_short);
93 				acl->a_entries[i].e_id = ACL_UNDEFINED_ID;
94 				break;
95 
96 			case ACL_USER:
97 			case ACL_GROUP:
98 				value += sizeof(struct jffs2_acl_entry);
99 				if (value > end)
100 					goto fail;
101 				acl->a_entries[i].e_id = je32_to_cpu(entry->e_id);
102 				break;
103 
104 			default:
105 				goto fail;
106 		}
107 	}
108 	if (value != end)
109 		goto fail;
110 	return acl;
111  fail:
112 	posix_acl_release(acl);
113 	return ERR_PTR(-EINVAL);
114 }
115 
116 static void *jffs2_acl_to_medium(const struct posix_acl *acl, size_t *size)
117 {
118 	struct jffs2_acl_header *header;
119 	struct jffs2_acl_entry *entry;
120 	void *e;
121 	size_t i;
122 
123 	*size = jffs2_acl_size(acl->a_count);
124 	header = kmalloc(sizeof(*header) + acl->a_count * sizeof(*entry), GFP_KERNEL);
125 	if (!header)
126 		return ERR_PTR(-ENOMEM);
127 	header->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
128 	e = header + 1;
129 	for (i=0; i < acl->a_count; i++) {
130 		entry = e;
131 		entry->e_tag = cpu_to_je16(acl->a_entries[i].e_tag);
132 		entry->e_perm = cpu_to_je16(acl->a_entries[i].e_perm);
133 		switch(acl->a_entries[i].e_tag) {
134 			case ACL_USER:
135 			case ACL_GROUP:
136 				entry->e_id = cpu_to_je32(acl->a_entries[i].e_id);
137 				e += sizeof(struct jffs2_acl_entry);
138 				break;
139 
140 			case ACL_USER_OBJ:
141 			case ACL_GROUP_OBJ:
142 			case ACL_MASK:
143 			case ACL_OTHER:
144 				e += sizeof(struct jffs2_acl_entry_short);
145 				break;
146 
147 			default:
148 				goto fail;
149 		}
150 	}
151 	return header;
152  fail:
153 	kfree(header);
154 	return ERR_PTR(-EINVAL);
155 }
156 
157 static struct posix_acl *jffs2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
158 {
159 	struct posix_acl *acl = JFFS2_ACL_NOT_CACHED;
160 
161 	spin_lock(&inode->i_lock);
162 	if (*i_acl != JFFS2_ACL_NOT_CACHED)
163 		acl = posix_acl_dup(*i_acl);
164 	spin_unlock(&inode->i_lock);
165 	return acl;
166 }
167 
168 static void jffs2_iset_acl(struct inode *inode, struct posix_acl **i_acl, struct posix_acl *acl)
169 {
170 	spin_lock(&inode->i_lock);
171 	if (*i_acl != JFFS2_ACL_NOT_CACHED)
172 		posix_acl_release(*i_acl);
173 	*i_acl = posix_acl_dup(acl);
174 	spin_unlock(&inode->i_lock);
175 }
176 
177 static struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
178 {
179 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
180 	struct posix_acl *acl;
181 	char *value = NULL;
182 	int rc, xprefix;
183 
184 	switch (type) {
185 	case ACL_TYPE_ACCESS:
186 		acl = jffs2_iget_acl(inode, &f->i_acl_access);
187 		if (acl != JFFS2_ACL_NOT_CACHED)
188 			return acl;
189 		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
190 		break;
191 	case ACL_TYPE_DEFAULT:
192 		acl = jffs2_iget_acl(inode, &f->i_acl_default);
193 		if (acl != JFFS2_ACL_NOT_CACHED)
194 			return acl;
195 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
196 		break;
197 	default:
198 		return ERR_PTR(-EINVAL);
199 	}
200 	rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
201 	if (rc > 0) {
202 		value = kmalloc(rc, GFP_KERNEL);
203 		if (!value)
204 			return ERR_PTR(-ENOMEM);
205 		rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
206 	}
207 	if (rc > 0) {
208 		acl = jffs2_acl_from_medium(value, rc);
209 	} else if (rc == -ENODATA || rc == -ENOSYS) {
210 		acl = NULL;
211 	} else {
212 		acl = ERR_PTR(rc);
213 	}
214 	if (value)
215 		kfree(value);
216 	if (!IS_ERR(acl)) {
217 		switch (type) {
218 		case ACL_TYPE_ACCESS:
219 			jffs2_iset_acl(inode, &f->i_acl_access, acl);
220 			break;
221 		case ACL_TYPE_DEFAULT:
222 			jffs2_iset_acl(inode, &f->i_acl_default, acl);
223 			break;
224 		}
225 	}
226 	return acl;
227 }
228 
229 static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
230 {
231 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
232 	size_t size = 0;
233 	char *value = NULL;
234 	int rc, xprefix;
235 
236 	if (S_ISLNK(inode->i_mode))
237 		return -EOPNOTSUPP;
238 
239 	switch (type) {
240 	case ACL_TYPE_ACCESS:
241 		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
242 		if (acl) {
243 			mode_t mode = inode->i_mode;
244 			rc = posix_acl_equiv_mode(acl, &mode);
245 			if (rc < 0)
246 				return rc;
247 			if (inode->i_mode != mode) {
248 				inode->i_mode = mode;
249 				jffs2_dirty_inode(inode);
250 			}
251 			if (rc == 0)
252 				acl = NULL;
253 		}
254 		break;
255 	case ACL_TYPE_DEFAULT:
256 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
257 		if (!S_ISDIR(inode->i_mode))
258 			return acl ? -EACCES : 0;
259 		break;
260 	default:
261 		return -EINVAL;
262 	}
263 	if (acl) {
264 		value = jffs2_acl_to_medium(acl, &size);
265 		if (IS_ERR(value))
266 			return PTR_ERR(value);
267 	}
268 
269 	rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
270 	if (!value && rc == -ENODATA)
271 		rc = 0;
272 	if (value)
273 		kfree(value);
274 	if (!rc) {
275 		switch(type) {
276 		case ACL_TYPE_ACCESS:
277 			jffs2_iset_acl(inode, &f->i_acl_access, acl);
278 			break;
279 		case ACL_TYPE_DEFAULT:
280 			jffs2_iset_acl(inode, &f->i_acl_default, acl);
281 			break;
282 		}
283 	}
284 	return rc;
285 }
286 
287 static int jffs2_check_acl(struct inode *inode, int mask)
288 {
289 	struct posix_acl *acl;
290 	int rc;
291 
292 	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
293 	if (IS_ERR(acl))
294 		return PTR_ERR(acl);
295 	if (acl) {
296 		rc = posix_acl_permission(inode, acl, mask);
297 		posix_acl_release(acl);
298 		return rc;
299 	}
300 	return -EAGAIN;
301 }
302 
303 int jffs2_permission(struct inode *inode, int mask, struct nameidata *nd)
304 {
305 	return generic_permission(inode, mask, jffs2_check_acl);
306 }
307 
308 int jffs2_init_acl(struct inode *inode, struct inode *dir)
309 {
310 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
311 	struct posix_acl *acl = NULL, *clone;
312 	mode_t mode;
313 	int rc = 0;
314 
315 	f->i_acl_access = JFFS2_ACL_NOT_CACHED;
316 	f->i_acl_default = JFFS2_ACL_NOT_CACHED;
317 	if (!S_ISLNK(inode->i_mode)) {
318 		acl = jffs2_get_acl(dir, ACL_TYPE_DEFAULT);
319 		if (IS_ERR(acl))
320 			return PTR_ERR(acl);
321 		if (!acl)
322 			inode->i_mode &= ~current->fs->umask;
323 	}
324 	if (acl) {
325 		if (S_ISDIR(inode->i_mode)) {
326 			rc = jffs2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
327 			if (rc)
328 				goto cleanup;
329 		}
330 		clone = posix_acl_clone(acl, GFP_KERNEL);
331 		rc = -ENOMEM;
332 		if (!clone)
333 			goto cleanup;
334 		mode = inode->i_mode;
335 		rc = posix_acl_create_masq(clone, &mode);
336 		if (rc >= 0) {
337 			inode->i_mode = mode;
338 			if (rc > 0)
339 				rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
340 		}
341 		posix_acl_release(clone);
342 	}
343  cleanup:
344 	posix_acl_release(acl);
345 	return rc;
346 }
347 
348 void jffs2_clear_acl(struct inode *inode)
349 {
350 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
351 
352 	if (f->i_acl_access && f->i_acl_access != JFFS2_ACL_NOT_CACHED) {
353 		posix_acl_release(f->i_acl_access);
354 		f->i_acl_access = JFFS2_ACL_NOT_CACHED;
355 	}
356 	if (f->i_acl_default && f->i_acl_default != JFFS2_ACL_NOT_CACHED) {
357 		posix_acl_release(f->i_acl_default);
358 		f->i_acl_default = JFFS2_ACL_NOT_CACHED;
359 	}
360 }
361 
362 int jffs2_acl_chmod(struct inode *inode)
363 {
364 	struct posix_acl *acl, *clone;
365 	int rc;
366 
367 	if (S_ISLNK(inode->i_mode))
368 		return -EOPNOTSUPP;
369 	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
370 	if (IS_ERR(acl) || !acl)
371 		return PTR_ERR(acl);
372 	clone = posix_acl_clone(acl, GFP_KERNEL);
373 	posix_acl_release(acl);
374 	if (!clone)
375 		return -ENOMEM;
376 	rc = posix_acl_chmod_masq(clone, inode->i_mode);
377 	if (!rc)
378 		rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
379 	posix_acl_release(clone);
380 	return rc;
381 }
382 
383 static size_t jffs2_acl_access_listxattr(struct inode *inode, char *list, size_t list_size,
384 					 const char *name, size_t name_len)
385 {
386 	const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
387 
388 	if (list && retlen <= list_size)
389 		strcpy(list, POSIX_ACL_XATTR_ACCESS);
390 	return retlen;
391 }
392 
393 static size_t jffs2_acl_default_listxattr(struct inode *inode, char *list, size_t list_size,
394 					  const char *name, size_t name_len)
395 {
396 	const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
397 
398 	if (list && retlen <= list_size)
399 		strcpy(list, POSIX_ACL_XATTR_DEFAULT);
400 	return retlen;
401 }
402 
403 static int jffs2_acl_getxattr(struct inode *inode, int type, void *buffer, size_t size)
404 {
405 	struct posix_acl *acl;
406 	int rc;
407 
408 	acl = jffs2_get_acl(inode, type);
409 	if (IS_ERR(acl))
410 		return PTR_ERR(acl);
411 	if (!acl)
412 		return -ENODATA;
413 	rc = posix_acl_to_xattr(acl, buffer, size);
414 	posix_acl_release(acl);
415 
416 	return rc;
417 }
418 
419 static int jffs2_acl_access_getxattr(struct inode *inode, const char *name, void *buffer, size_t size)
420 {
421 	if (name[0] != '\0')
422 		return -EINVAL;
423 	return jffs2_acl_getxattr(inode, ACL_TYPE_ACCESS, buffer, size);
424 }
425 
426 static int jffs2_acl_default_getxattr(struct inode *inode, const char *name, void *buffer, size_t size)
427 {
428 	if (name[0] != '\0')
429 		return -EINVAL;
430 	return jffs2_acl_getxattr(inode, ACL_TYPE_DEFAULT, buffer, size);
431 }
432 
433 static int jffs2_acl_setxattr(struct inode *inode, int type, const void *value, size_t size)
434 {
435 	struct posix_acl *acl;
436 	int rc;
437 
438 	if ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
439 		return -EPERM;
440 
441 	if (value) {
442 		acl = posix_acl_from_xattr(value, size);
443 		if (IS_ERR(acl))
444 			return PTR_ERR(acl);
445 		if (acl) {
446 			rc = posix_acl_valid(acl);
447 			if (rc)
448 				goto out;
449 		}
450 	} else {
451 		acl = NULL;
452 	}
453 	rc = jffs2_set_acl(inode, type, acl);
454  out:
455 	posix_acl_release(acl);
456 	return rc;
457 }
458 
459 static int jffs2_acl_access_setxattr(struct inode *inode, const char *name,
460 				     const void *buffer, size_t size, int flags)
461 {
462 	if (name[0] != '\0')
463 		return -EINVAL;
464 	return jffs2_acl_setxattr(inode, ACL_TYPE_ACCESS, buffer, size);
465 }
466 
467 static int jffs2_acl_default_setxattr(struct inode *inode, const char *name,
468 				      const void *buffer, size_t size, int flags)
469 {
470 	if (name[0] != '\0')
471 		return -EINVAL;
472 	return jffs2_acl_setxattr(inode, ACL_TYPE_DEFAULT, buffer, size);
473 }
474 
475 struct xattr_handler jffs2_acl_access_xattr_handler = {
476 	.prefix	= POSIX_ACL_XATTR_ACCESS,
477 	.list	= jffs2_acl_access_listxattr,
478 	.get	= jffs2_acl_access_getxattr,
479 	.set	= jffs2_acl_access_setxattr,
480 };
481 
482 struct xattr_handler jffs2_acl_default_xattr_handler = {
483 	.prefix	= POSIX_ACL_XATTR_DEFAULT,
484 	.list	= jffs2_acl_default_listxattr,
485 	.get	= jffs2_acl_default_getxattr,
486 	.set	= jffs2_acl_default_setxattr,
487 };
488