xref: /openbmc/linux/fs/jffs2/acl.c (revision 64c70b1c) 
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 static 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 				inode->i_mode = mode;
251 				jffs2_dirty_inode(inode);
252 			}
253 			if (rc == 0)
254 				acl = NULL;
255 		}
256 		break;
257 	case ACL_TYPE_DEFAULT:
258 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
259 		if (!S_ISDIR(inode->i_mode))
260 			return acl ? -EACCES : 0;
261 		break;
262 	default:
263 		return -EINVAL;
264 	}
265 	if (acl) {
266 		value = jffs2_acl_to_medium(acl, &size);
267 		if (IS_ERR(value))
268 			return PTR_ERR(value);
269 	}
270 
271 	rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
272 	if (!value && rc == -ENODATA)
273 		rc = 0;
274 	if (value)
275 		kfree(value);
276 	if (!rc) {
277 		switch(type) {
278 		case ACL_TYPE_ACCESS:
279 			jffs2_iset_acl(inode, &f->i_acl_access, acl);
280 			break;
281 		case ACL_TYPE_DEFAULT:
282 			jffs2_iset_acl(inode, &f->i_acl_default, acl);
283 			break;
284 		}
285 	}
286 	return rc;
287 }
288 
289 static int jffs2_check_acl(struct inode *inode, int mask)
290 {
291 	struct posix_acl *acl;
292 	int rc;
293 
294 	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
295 	if (IS_ERR(acl))
296 		return PTR_ERR(acl);
297 	if (acl) {
298 		rc = posix_acl_permission(inode, acl, mask);
299 		posix_acl_release(acl);
300 		return rc;
301 	}
302 	return -EAGAIN;
303 }
304 
305 int jffs2_permission(struct inode *inode, int mask, struct nameidata *nd)
306 {
307 	return generic_permission(inode, mask, jffs2_check_acl);
308 }
309 
310 int jffs2_init_acl(struct inode *inode, struct inode *dir)
311 {
312 	struct jffs2_inode_info *f = JFFS2_INODE_INFO(inode);
313 	struct posix_acl *acl = NULL, *clone;
314 	mode_t mode;
315 	int rc = 0;
316 
317 	f->i_acl_access = JFFS2_ACL_NOT_CACHED;
318 	f->i_acl_default = JFFS2_ACL_NOT_CACHED;
319 	if (!S_ISLNK(inode->i_mode)) {
320 		acl = jffs2_get_acl(dir, ACL_TYPE_DEFAULT);
321 		if (IS_ERR(acl))
322 			return PTR_ERR(acl);
323 		if (!acl)
324 			inode->i_mode &= ~current->fs->umask;
325 	}
326 	if (acl) {
327 		if (S_ISDIR(inode->i_mode)) {
328 			rc = jffs2_set_acl(inode, ACL_TYPE_DEFAULT, acl);
329 			if (rc)
330 				goto cleanup;
331 		}
332 		clone = posix_acl_clone(acl, GFP_KERNEL);
333 		rc = -ENOMEM;
334 		if (!clone)
335 			goto cleanup;
336 		mode = inode->i_mode;
337 		rc = posix_acl_create_masq(clone, &mode);
338 		if (rc >= 0) {
339 			inode->i_mode = mode;
340 			if (rc > 0)
341 				rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
342 		}
343 		posix_acl_release(clone);
344 	}
345  cleanup:
346 	posix_acl_release(acl);
347 	return rc;
348 }
349 
350 void jffs2_clear_acl(struct jffs2_inode_info *f)
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