xref: /openbmc/linux/fs/jffs2/acl.c (revision 7e40145e) 
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 | ATTR_CTIME;
238 				attr.ia_mode = mode;
239 				attr.ia_ctime = CURRENT_TIME_SEC;
240 				rc = jffs2_do_setattr(inode, &attr);
241 				if (rc < 0)
242 					return rc;
243 			}
244 			if (rc == 0)
245 				acl = NULL;
246 		}
247 		break;
248 	case ACL_TYPE_DEFAULT:
249 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
250 		if (!S_ISDIR(inode->i_mode))
251 			return acl ? -EACCES : 0;
252 		break;
253 	default:
254 		return -EINVAL;
255 	}
256 	rc = __jffs2_set_acl(inode, xprefix, acl);
257 	if (!rc)
258 		set_cached_acl(inode, type, acl);
259 	return rc;
260 }
261 
262 int jffs2_check_acl(struct inode *inode, int mask)
263 {
264 	struct posix_acl *acl;
265 	int rc;
266 
267 	if (mask & MAY_NOT_BLOCK)
268 		return -ECHILD;
269 
270 	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
271 	if (IS_ERR(acl))
272 		return PTR_ERR(acl);
273 	if (acl) {
274 		rc = posix_acl_permission(inode, acl, mask);
275 		posix_acl_release(acl);
276 		return rc;
277 	}
278 	return -EAGAIN;
279 }
280 
281 int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, int *i_mode)
282 {
283 	struct posix_acl *acl, *clone;
284 	int rc;
285 
286 	cache_no_acl(inode);
287 
288 	if (S_ISLNK(*i_mode))
289 		return 0;	/* Symlink always has no-ACL */
290 
291 	acl = jffs2_get_acl(dir_i, ACL_TYPE_DEFAULT);
292 	if (IS_ERR(acl))
293 		return PTR_ERR(acl);
294 
295 	if (!acl) {
296 		*i_mode &= ~current_umask();
297 	} else {
298 		if (S_ISDIR(*i_mode))
299 			set_cached_acl(inode, ACL_TYPE_DEFAULT, acl);
300 
301 		clone = posix_acl_clone(acl, GFP_KERNEL);
302 		if (!clone)
303 			return -ENOMEM;
304 		rc = posix_acl_create_masq(clone, (mode_t *)i_mode);
305 		if (rc < 0) {
306 			posix_acl_release(clone);
307 			return rc;
308 		}
309 		if (rc > 0)
310 			set_cached_acl(inode, ACL_TYPE_ACCESS, clone);
311 
312 		posix_acl_release(clone);
313 	}
314 	return 0;
315 }
316 
317 int jffs2_init_acl_post(struct inode *inode)
318 {
319 	int rc;
320 
321 	if (inode->i_default_acl) {
322 		rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
323 		if (rc)
324 			return rc;
325 	}
326 
327 	if (inode->i_acl) {
328 		rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
329 		if (rc)
330 			return rc;
331 	}
332 
333 	return 0;
334 }
335 
336 int jffs2_acl_chmod(struct inode *inode)
337 {
338 	struct posix_acl *acl, *clone;
339 	int rc;
340 
341 	if (S_ISLNK(inode->i_mode))
342 		return -EOPNOTSUPP;
343 	acl = jffs2_get_acl(inode, ACL_TYPE_ACCESS);
344 	if (IS_ERR(acl) || !acl)
345 		return PTR_ERR(acl);
346 	clone = posix_acl_clone(acl, GFP_KERNEL);
347 	posix_acl_release(acl);
348 	if (!clone)
349 		return -ENOMEM;
350 	rc = posix_acl_chmod_masq(clone, inode->i_mode);
351 	if (!rc)
352 		rc = jffs2_set_acl(inode, ACL_TYPE_ACCESS, clone);
353 	posix_acl_release(clone);
354 	return rc;
355 }
356 
357 static size_t jffs2_acl_access_listxattr(struct dentry *dentry, char *list,
358 		size_t list_size, const char *name, size_t name_len, int type)
359 {
360 	const int retlen = sizeof(POSIX_ACL_XATTR_ACCESS);
361 
362 	if (list && retlen <= list_size)
363 		strcpy(list, POSIX_ACL_XATTR_ACCESS);
364 	return retlen;
365 }
366 
367 static size_t jffs2_acl_default_listxattr(struct dentry *dentry, char *list,
368 		size_t list_size, const char *name, size_t name_len, int type)
369 {
370 	const int retlen = sizeof(POSIX_ACL_XATTR_DEFAULT);
371 
372 	if (list && retlen <= list_size)
373 		strcpy(list, POSIX_ACL_XATTR_DEFAULT);
374 	return retlen;
375 }
376 
377 static int jffs2_acl_getxattr(struct dentry *dentry, const char *name,
378 		void *buffer, size_t size, int type)
379 {
380 	struct posix_acl *acl;
381 	int rc;
382 
383 	if (name[0] != '\0')
384 		return -EINVAL;
385 
386 	acl = jffs2_get_acl(dentry->d_inode, type);
387 	if (IS_ERR(acl))
388 		return PTR_ERR(acl);
389 	if (!acl)
390 		return -ENODATA;
391 	rc = posix_acl_to_xattr(acl, buffer, size);
392 	posix_acl_release(acl);
393 
394 	return rc;
395 }
396 
397 static int jffs2_acl_setxattr(struct dentry *dentry, const char *name,
398 		const void *value, size_t size, int flags, int type)
399 {
400 	struct posix_acl *acl;
401 	int rc;
402 
403 	if (name[0] != '\0')
404 		return -EINVAL;
405 	if (!inode_owner_or_capable(dentry->d_inode))
406 		return -EPERM;
407 
408 	if (value) {
409 		acl = posix_acl_from_xattr(value, size);
410 		if (IS_ERR(acl))
411 			return PTR_ERR(acl);
412 		if (acl) {
413 			rc = posix_acl_valid(acl);
414 			if (rc)
415 				goto out;
416 		}
417 	} else {
418 		acl = NULL;
419 	}
420 	rc = jffs2_set_acl(dentry->d_inode, type, acl);
421  out:
422 	posix_acl_release(acl);
423 	return rc;
424 }
425 
426 const struct xattr_handler jffs2_acl_access_xattr_handler = {
427 	.prefix	= POSIX_ACL_XATTR_ACCESS,
428 	.flags	= ACL_TYPE_DEFAULT,
429 	.list	= jffs2_acl_access_listxattr,
430 	.get	= jffs2_acl_getxattr,
431 	.set	= jffs2_acl_setxattr,
432 };
433 
434 const struct xattr_handler jffs2_acl_default_xattr_handler = {
435 	.prefix	= POSIX_ACL_XATTR_DEFAULT,
436 	.flags	= ACL_TYPE_DEFAULT,
437 	.list	= jffs2_acl_default_listxattr,
438 	.get	= jffs2_acl_getxattr,
439 	.set	= jffs2_acl_setxattr,
440 };
441