xref: /linux/fs/jffs2/acl.c (revision c537b994505099b7197e7d3125b942ecbcc51eb6) 
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/sched.h>
15 #include <linux/time.h>
16 #include <linux/crc32.h>
17 #include <linux/jffs2.h>
18 #include <linux/xattr.h>
19 #include <linux/posix_acl_xattr.h>
20 #include <linux/mtd/mtd.h>
21 #include "nodelist.h"
22 
23 static size_t jffs2_acl_size(int count)
24 {
25 	if (count <= 4) {
26 		return sizeof(struct jffs2_acl_header)
27 		       + count * sizeof(struct jffs2_acl_entry_short);
28 	} else {
29 		return sizeof(struct jffs2_acl_header)
30 		       + 4 * sizeof(struct jffs2_acl_entry_short)
31 		       + (count - 4) * sizeof(struct jffs2_acl_entry);
32 	}
33 }
34 
35 static int jffs2_acl_count(size_t size)
36 {
37 	size_t s;
38 
39 	size -= sizeof(struct jffs2_acl_header);
40 	s = size - 4 * sizeof(struct jffs2_acl_entry_short);
41 	if (s < 0) {
42 		if (size % sizeof(struct jffs2_acl_entry_short))
43 			return -1;
44 		return size / sizeof(struct jffs2_acl_entry_short);
45 	} else {
46 		if (s % sizeof(struct jffs2_acl_entry))
47 			return -1;
48 		return s / sizeof(struct jffs2_acl_entry) + 4;
49 	}
50 }
51 
52 static struct posix_acl *jffs2_acl_from_medium(void *value, size_t size)
53 {
54 	void *end = value + size;
55 	struct jffs2_acl_header *header = value;
56 	struct jffs2_acl_entry *entry;
57 	struct posix_acl *acl;
58 	uint32_t ver;
59 	int i, count;
60 
61 	if (!value)
62 		return NULL;
63 	if (size < sizeof(struct jffs2_acl_header))
64 		return ERR_PTR(-EINVAL);
65 	ver = je32_to_cpu(header->a_version);
66 	if (ver != JFFS2_ACL_VERSION) {
67 		JFFS2_WARNING("Invalid ACL version. (=%u)\n", ver);
68 		return ERR_PTR(-EINVAL);
69 	}
70 
71 	value += sizeof(struct jffs2_acl_header);
72 	count = jffs2_acl_count(size);
73 	if (count < 0)
74 		return ERR_PTR(-EINVAL);
75 	if (count == 0)
76 		return NULL;
77 
78 	acl = posix_acl_alloc(count, GFP_KERNEL);
79 	if (!acl)
80 		return ERR_PTR(-ENOMEM);
81 
82 	for (i=0; i < count; i++) {
83 		entry = value;
84 		if (value + sizeof(struct jffs2_acl_entry_short) > end)
85 			goto fail;
86 		acl->a_entries[i].e_tag = je16_to_cpu(entry->e_tag);
87 		acl->a_entries[i].e_perm = je16_to_cpu(entry->e_perm);
88 		switch (acl->a_entries[i].e_tag) {
89 			case ACL_USER_OBJ:
90 			case ACL_GROUP_OBJ:
91 			case ACL_MASK:
92 			case ACL_OTHER:
93 				value += sizeof(struct jffs2_acl_entry_short);
94 				acl->a_entries[i].e_id = ACL_UNDEFINED_ID;
95 				break;
96 
97 			case ACL_USER:
98 			case ACL_GROUP:
99 				value += sizeof(struct jffs2_acl_entry);
100 				if (value > end)
101 					goto fail;
102 				acl->a_entries[i].e_id = je32_to_cpu(entry->e_id);
103 				break;
104 
105 			default:
106 				goto fail;
107 		}
108 	}
109 	if (value != end)
110 		goto fail;
111 	return acl;
112  fail:
113 	posix_acl_release(acl);
114 	return ERR_PTR(-EINVAL);
115 }
116 
117 static void *jffs2_acl_to_medium(const struct posix_acl *acl, size_t *size)
118 {
119 	struct jffs2_acl_header *header;
120 	struct jffs2_acl_entry *entry;
121 	void *e;
122 	size_t i;
123 
124 	*size = jffs2_acl_size(acl->a_count);
125 	header = kmalloc(sizeof(*header) + acl->a_count * sizeof(*entry), GFP_KERNEL);
126 	if (!header)
127 		return ERR_PTR(-ENOMEM);
128 	header->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
129 	e = header + 1;
130 	for (i=0; i < acl->a_count; i++) {
131 		entry = e;
132 		entry->e_tag = cpu_to_je16(acl->a_entries[i].e_tag);
133 		entry->e_perm = cpu_to_je16(acl->a_entries[i].e_perm);
134 		switch(acl->a_entries[i].e_tag) {
135 			case ACL_USER:
136 			case ACL_GROUP:
137 				entry->e_id = cpu_to_je32(acl->a_entries[i].e_id);
138 				e += sizeof(struct jffs2_acl_entry);
139 				break;
140 
141 			case ACL_USER_OBJ:
142 			case ACL_GROUP_OBJ:
143 			case ACL_MASK:
144 			case ACL_OTHER:
145 				e += sizeof(struct jffs2_acl_entry_short);
146 				break;
147 
148 			default:
149 				goto fail;
150 		}
151 	}
152 	return header;
153  fail:
154 	kfree(header);
155 	return ERR_PTR(-EINVAL);
156 }
157 
158 static struct posix_acl *jffs2_iget_acl(struct inode *inode, struct posix_acl **i_acl)
159 {
160 	struct posix_acl *acl = JFFS2_ACL_NOT_CACHED;
161 
162 	spin_lock(&inode->i_lock);
163 	if (*i_acl != JFFS2_ACL_NOT_CACHED)
164 		acl = posix_acl_dup(*i_acl);
165 	spin_unlock(&inode->i_lock);
166 	return acl;
167 }
168 
169 static void jffs2_iset_acl(struct inode *inode, struct posix_acl **i_acl, struct posix_acl *acl)
170 {
171 	spin_lock(&inode->i_lock);
172 	if (*i_acl != JFFS2_ACL_NOT_CACHED)
173 		posix_acl_release(*i_acl);
174 	*i_acl = posix_acl_dup(acl);
175 	spin_unlock(&inode->i_lock);
176 }
177 
178 static struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
179 {
180 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
181 	struct posix_acl *acl;
182 	char *value = NULL;
183 	int rc, xprefix;
184 
185 	switch (type) {
186 	case ACL_TYPE_ACCESS:
187 		acl = jffs2_iget_acl(inode, &f->i_acl_access);
188 		if (acl != JFFS2_ACL_NOT_CACHED)
189 			return acl;
190 		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
191 		break;
192 	case ACL_TYPE_DEFAULT:
193 		acl = jffs2_iget_acl(inode, &f->i_acl_default);
194 		if (acl != JFFS2_ACL_NOT_CACHED)
195 			return acl;
196 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
197 		break;
198 	default:
199 		return ERR_PTR(-EINVAL);
200 	}
201 	rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
202 	if (rc > 0) {
203 		value = kmalloc(rc, GFP_KERNEL);
204 		if (!value)
205 			return ERR_PTR(-ENOMEM);
206 		rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
207 	}
208 	if (rc > 0) {
209 		acl = jffs2_acl_from_medium(value, rc);
210 	} else if (rc == -ENODATA || rc == -ENOSYS) {
211 		acl = NULL;
212 	} else {
213 		acl = ERR_PTR(rc);
214 	}
215 	if (value)
216 		kfree(value);
217 	if (!IS_ERR(acl)) {
218 		switch (type) {
219 		case ACL_TYPE_ACCESS:
220 			jffs2_iset_acl(inode, &f->i_acl_access, acl);
221 			break;
222 		case ACL_TYPE_DEFAULT:
223 			jffs2_iset_acl(inode, &f->i_acl_default, acl);
224 			break;
225 		}
226 	}
227 	return acl;
228 }
229 
230 static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
231 {
232 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
233 	size_t size = 0;
234 	char *value = NULL;
235 	int rc, xprefix;
236 
237 	if (S_ISLNK(inode->i_mode))
238 		return -EOPNOTSUPP;
239 
240 	switch (type) {
241 	case ACL_TYPE_ACCESS:
242 		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
243 		if (acl) {
244 			mode_t mode = inode->i_mode;
245 			rc = posix_acl_equiv_mode(acl, &mode);
246 			if (rc < 0)
247 				return rc;
248 			if (inode->i_mode != mode) {
249 				inode->i_mode = mode;
250 				jffs2_dirty_inode(inode);
251 			}
252 			if (rc == 0)
253 				acl = NULL;
254 		}
255 		break;
256 	case ACL_TYPE_DEFAULT:
257 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
258 		if (!S_ISDIR(inode->i_mode))
259 			return acl ? -EACCES : 0;
260 		break;
261 	default:
262 		return -EINVAL;
263 	}
264 	if (acl) {
265 		value = jffs2_acl_to_medium(acl, &size);
266 		if (IS_ERR(value))
267 			return PTR_ERR(value);
268 	}
269 
270 	rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
271 	if (!value && rc == -ENODATA)
272 		rc = 0;
273 	if (value)
274 		kfree(value);
275 	if (!rc) {
276 		switch(type) {
277 		case ACL_TYPE_ACCESS:
278 			jffs2_iset_acl(inode, &f->i_acl_access, acl);
279 			break;
280 		case ACL_TYPE_DEFAULT:
281 			jffs2_iset_acl(inode, &f->i_acl_default, acl);
282 			break;
283 		}
284 	}
285 	return rc;
286 }
287 
288 static int jffs2_check_acl(struct inode *inode, int mask)
289 {
290 	struct posix_acl *acl;
291 	int rc;
292 
293 	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
294 	if (IS_ERR(acl))
295 		return PTR_ERR(acl);
296 	if (acl) {
297 		rc = posix_acl_permission(inode, acl, mask);
298 		posix_acl_release(acl);
299 		return rc;
300 	}
301 	return -EAGAIN;
302 }
303 
304 int jffs2_permission(struct inode *inode, int mask, struct nameidata *nd)
305 {
306 	return generic_permission(inode, mask, jffs2_check_acl);
307 }
308 
309 int jffs2_init_acl(struct inode *inode, struct inode *dir)
310 {
311 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
312 	struct posix_acl *acl = NULL, *clone;
313 	mode_t mode;
314 	int rc = 0;
315 
316 	f->i_acl_access = JFFS2_ACL_NOT_CACHED;
317 	f->i_acl_default = JFFS2_ACL_NOT_CACHED;
318 	if (!S_ISLNK(inode->i_mode)) {
319 		acl = jffs2_get_acl(dir, ACL_TYPE_DEFAULT);
320 		if (IS_ERR(acl))
321 			return PTR_ERR(acl);
322 		if (!acl)
323 			inode->i_mode &= ~current->fs->umask;
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 ((current->fsuid != inode->i_uid) && !capable(CAP_FOWNER))
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