xref: /linux/fs/jffs2/acl.c (revision 2277ab4a1df50e05bc732fe9488d4e902bb8399a) 
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 	if (size < 4 * sizeof(struct jffs2_acl_entry_short)) {
42 		if (size % sizeof(struct jffs2_acl_entry_short))
43 			return -1;
44 		return size / sizeof(struct jffs2_acl_entry_short);
45 	} else {
46 		s = size - 4 * sizeof(struct jffs2_acl_entry_short);
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_get_acl(struct inode *inode, int type)
160 {
161 	struct posix_acl *acl;
162 	char *value = NULL;
163 	int rc, xprefix;
164 
165 	acl = get_cached_acl(inode, type);
166 	if (acl != ACL_NOT_CACHED)
167 		return acl;
168 
169 	switch (type) {
170 	case ACL_TYPE_ACCESS:
171 		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
172 		break;
173 	case ACL_TYPE_DEFAULT:
174 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
175 		break;
176 	default:
177 		BUG();
178 	}
179 	rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
180 	if (rc > 0) {
181 		value = kmalloc(rc, GFP_KERNEL);
182 		if (!value)
183 			return ERR_PTR(-ENOMEM);
184 		rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
185 	}
186 	if (rc > 0) {
187 		acl = jffs2_acl_from_medium(value, rc);
188 	} else if (rc == -ENODATA || rc == -ENOSYS) {
189 		acl = NULL;
190 	} else {
191 		acl = ERR_PTR(rc);
192 	}
193 	if (value)
194 		kfree(value);
195 	if (!IS_ERR(acl))
196 		set_cached_acl(inode, type, acl);
197 	return acl;
198 }
199 
200 static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
201 {
202 	char *value = NULL;
203 	size_t size = 0;
204 	int rc;
205 
206 	if (acl) {
207 		value = jffs2_acl_to_medium(acl, &size);
208 		if (IS_ERR(value))
209 			return PTR_ERR(value);
210 	}
211 	rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
212 	if (!value && rc == -ENODATA)
213 		rc = 0;
214 	kfree(value);
215 
216 	return rc;
217 }
218 
219 static int jffs2_set_acl(struct inode *inode, int type, struct posix_acl *acl)
220 {
221 	int rc, xprefix;
222 
223 	if (S_ISLNK(inode->i_mode))
224 		return -EOPNOTSUPP;
225 
226 	switch (type) {
227 	case ACL_TYPE_ACCESS:
228 		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
229 		if (acl) {
230 			mode_t mode = inode->i_mode;
231 			rc = posix_acl_equiv_mode(acl, &mode);
232 			if (rc < 0)
233 				return rc;
234 			if (inode->i_mode != mode) {
235 				struct iattr attr;
236 
237 				attr.ia_valid = ATTR_MODE;
238 				attr.ia_mode = mode;
239 				rc = jffs2_do_setattr(inode, &attr);
240 				if (rc < 0)
241 					return rc;
242 			}
243 			if (rc == 0)
244 				acl = NULL;
245 		}
246 		break;
247 	case ACL_TYPE_DEFAULT:
248 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
249 		if (!S_ISDIR(inode->i_mode))
250 			return acl ? -EACCES : 0;
251 		break;
252 	default:
253 		return -EINVAL;
254 	}
255 	rc = __jffs2_set_acl(inode, xprefix, acl);
256 	if (!rc)
257 		set_cached_acl(inode, type, acl);
258 	return rc;
259 }
260 
261 static int jffs2_check_acl(struct inode *inode, int mask)
262 {
263 	struct posix_acl *acl;
264 	int rc;
265 
266 	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
267 	if (IS_ERR(acl))
268 		return PTR_ERR(acl);
269 	if (acl) {
270 		rc = posix_acl_permission(inode, acl, mask);
271 		posix_acl_release(acl);
272 		return rc;
273 	}
274 	return -EAGAIN;
275 }
276 
277 int jffs2_permission(struct inode *inode, int mask)
278 {
279 	return generic_permission(inode, mask, jffs2_check_acl);
280 }
281 
282 int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, int *i_mode)
283 {
284 	struct posix_acl *acl, *clone;
285 	int rc;
286 
287 	cache_no_acl(inode);
288 
289 	if (S_ISLNK(*i_mode))
290 		return 0;	/* Symlink always has no-ACL */
291 
292 	acl = jffs2_get_acl(dir_i, ACL_TYPE_DEFAULT);
293 	if (IS_ERR(acl))
294 		return PTR_ERR(acl);
295 
296 	if (!acl) {
297 		*i_mode &= ~current_umask();
298 	} else {
299 		if (S_ISDIR(*i_mode))
300 			set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
301 
302 		clone = posix_acl_clone(acl, GFP_KERNEL);
303 		if (!clone)
304 			return -ENOMEM;
305 		rc = posix_acl_create_masq(clone, (mode_t *)i_mode);
306 		if (rc < 0) {
307 			posix_acl_release(clone);
308 			return rc;
309 		}
310 		if (rc > 0)
311 			set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
312 
313 		posix_acl_release(clone);
314 	}
315 	return 0;
316 }
317 
318 int jffs2_init_acl_post(struct inode *inode)
319 {
320 	int rc;
321 
322 	if (inode->i_default_acl) {
323 		rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
324 		if (rc)
325 			return rc;
326 	}
327 
328 	if (inode->i_acl) {
329 		rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
330 		if (rc)
331 			return rc;
332 	}
333 
334 	return 0;
335 }
336 
337 int jffs2_acl_chmod(struct inode *inode)
338 {
339 	struct posix_acl *acl, *clone;
340 	int rc;
341 
342 	if (S_ISLNK(inode->i_mode))
343 		return -EOPNOTSUPP;
344 	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
345 	if (IS_ERR(acl) || !acl)
346 		return PTR_ERR(acl);
347 	clone = posix_acl_clone(acl, GFP_KERNEL);
348 	posix_acl_release(acl);
349 	if (!clone)
350 		return -ENOMEM;
351 	rc = posix_acl_chmod_masq(clone, inode->i_mode);
352 	if (!rc)
353 		rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
354 	posix_acl_release(clone);
355 	return rc;
356 }
357 
358 static size_t jffs2_acl_access_listxattr(struct inode *inode, char *list, size_t list_size,
359 					 const char *name, size_t name_len)
360 {
361 	const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
362 
363 	if (list && retlen <= list_size)
364 		strcpy(list, POSIX_ACL_XATTR_ACCESS);
365 	return retlen;
366 }
367 
368 static size_t jffs2_acl_default_listxattr(struct inode *inode, char *list, size_t list_size,
369 					  const char *name, size_t name_len)
370 {
371 	const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
372 
373 	if (list && retlen <= list_size)
374 		strcpy(list, POSIX_ACL_XATTR_DEFAULT);
375 	return retlen;
376 }
377 
378 static int jffs2_acl_getxattr(struct inode *inode, int type, void *buffer, size_t size)
379 {
380 	struct posix_acl *acl;
381 	int rc;
382 
383 	acl = jffs2_get_acl(inode, type);
384 	if (IS_ERR(acl))
385 		return PTR_ERR(acl);
386 	if (!acl)
387 		return -ENODATA;
388 	rc = posix_acl_to_xattr(acl, buffer, size);
389 	posix_acl_release(acl);
390 
391 	return rc;
392 }
393 
394 static int jffs2_acl_access_getxattr(struct inode *inode, const char *name, void *buffer, size_t size)
395 {
396 	if (name[0] != '\0')
397 		return -EINVAL;
398 	return jffs2_acl_getxattr(inode, ACL_TYPE_ACCESS, buffer, size);
399 }
400 
401 static int jffs2_acl_default_getxattr(struct inode *inode, const char *name, void *buffer, size_t size)
402 {
403 	if (name[0] != '\0')
404 		return -EINVAL;
405 	return jffs2_acl_getxattr(inode, ACL_TYPE_DEFAULT, buffer, size);
406 }
407 
408 static int jffs2_acl_setxattr(struct inode *inode, int type, const void *value, size_t size)
409 {
410 	struct posix_acl *acl;
411 	int rc;
412 
413 	if (!is_owner_or_cap(inode))
414 		return -EPERM;
415 
416 	if (value) {
417 		acl = posix_acl_from_xattr(value, size);
418 		if (IS_ERR(acl))
419 			return PTR_ERR(acl);
420 		if (acl) {
421 			rc = posix_acl_valid(acl);
422 			if (rc)
423 				goto out;
424 		}
425 	} else {
426 		acl = NULL;
427 	}
428 	rc = jffs2_set_acl(inode, type, acl);
429  out:
430 	posix_acl_release(acl);
431 	return rc;
432 }
433 
434 static int jffs2_acl_access_setxattr(struct inode *inode, const char *name,
435 				     const void *buffer, size_t size, int flags)
436 {
437 	if (name[0] != '\0')
438 		return -EINVAL;
439 	return jffs2_acl_setxattr(inode, ACL_TYPE_ACCESS, buffer, size);
440 }
441 
442 static int jffs2_acl_default_setxattr(struct inode *inode, const char *name,
443 				      const void *buffer, size_t size, int flags)
444 {
445 	if (name[0] != '\0')
446 		return -EINVAL;
447 	return jffs2_acl_setxattr(inode, ACL_TYPE_DEFAULT, buffer, size);
448 }
449 
450 struct xattr_handler jffs2_acl_access_xattr_handler = {
451 	.prefix	= POSIX_ACL_XATTR_ACCESS,
452 	.list	= jffs2_acl_access_listxattr,
453 	.get	= jffs2_acl_access_getxattr,
454 	.set	= jffs2_acl_access_setxattr,
455 };
456 
457 struct xattr_handler jffs2_acl_default_xattr_handler = {
458 	.prefix	= POSIX_ACL_XATTR_DEFAULT,
459 	.list	= jffs2_acl_default_listxattr,
460 	.get	= jffs2_acl_default_getxattr,
461 	.set	= jffs2_acl_default_setxattr,
462 };
463