acl.c revision 0cad6246
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <linux/kernel.h>
15#include <linux/slab.h>
16#include <linux/fs.h>
17#include <linux/sched.h>
18#include <linux/time.h>
19#include <linux/crc32.h>
20#include <linux/jffs2.h>
21#include <linux/xattr.h>
22#include <linux/posix_acl_xattr.h>
23#include <linux/mtd/mtd.h>
24#include "nodelist.h"
25
26static size_t jffs2_acl_size(int count)
27{
28	if (count <= 4) {
29		return sizeof(struct jffs2_acl_header)
30		       + count * sizeof(struct jffs2_acl_entry_short);
31	} else {
32		return sizeof(struct jffs2_acl_header)
33		       + 4 * sizeof(struct jffs2_acl_entry_short)
34		       + (count - 4) * sizeof(struct jffs2_acl_entry);
35	}
36}
37
38static int jffs2_acl_count(size_t size)
39{
40	size_t s;
41
42	size -= sizeof(struct jffs2_acl_header);
43	if (size < 4 * sizeof(struct jffs2_acl_entry_short)) {
44		if (size % sizeof(struct jffs2_acl_entry_short))
45			return -1;
46		return size / sizeof(struct jffs2_acl_entry_short);
47	} else {
48		s = size - 4 * sizeof(struct jffs2_acl_entry_short);
49		if (s % sizeof(struct jffs2_acl_entry))
50			return -1;
51		return s / sizeof(struct jffs2_acl_entry) + 4;
52	}
53}
54
55static struct posix_acl *jffs2_acl_from_medium(void *value, size_t size)
56{
57	void *end = value + size;
58	struct jffs2_acl_header *header = value;
59	struct jffs2_acl_entry *entry;
60	struct posix_acl *acl;
61	uint32_t ver;
62	int i, count;
63
64	if (!value)
65		return NULL;
66	if (size < sizeof(struct jffs2_acl_header))
67		return ERR_PTR(-EINVAL);
68	ver = je32_to_cpu(header->a_version);
69	if (ver != JFFS2_ACL_VERSION) {
70		JFFS2_WARNING("Invalid ACL version. (=%u)\n", ver);
71		return ERR_PTR(-EINVAL);
72	}
73
74	value += sizeof(struct jffs2_acl_header);
75	count = jffs2_acl_count(size);
76	if (count < 0)
77		return ERR_PTR(-EINVAL);
78	if (count == 0)
79		return NULL;
80
81	acl = posix_acl_alloc(count, GFP_KERNEL);
82	if (!acl)
83		return ERR_PTR(-ENOMEM);
84
85	for (i=0; i < count; i++) {
86		entry = value;
87		if (value + sizeof(struct jffs2_acl_entry_short) > end)
88			goto fail;
89		acl->a_entries[i].e_tag = je16_to_cpu(entry->e_tag);
90		acl->a_entries[i].e_perm = je16_to_cpu(entry->e_perm);
91		switch (acl->a_entries[i].e_tag) {
92			case ACL_USER_OBJ:
93			case ACL_GROUP_OBJ:
94			case ACL_MASK:
95			case ACL_OTHER:
96				value += sizeof(struct jffs2_acl_entry_short);
97				break;
98
99			case ACL_USER:
100				value += sizeof(struct jffs2_acl_entry);
101				if (value > end)
102					goto fail;
103				acl->a_entries[i].e_uid =
104					make_kuid(&init_user_ns,
105						  je32_to_cpu(entry->e_id));
106				break;
107			case ACL_GROUP:
108				value += sizeof(struct jffs2_acl_entry);
109				if (value > end)
110					goto fail;
111				acl->a_entries[i].e_gid =
112					make_kgid(&init_user_ns,
113						  je32_to_cpu(entry->e_id));
114				break;
115
116			default:
117				goto fail;
118		}
119	}
120	if (value != end)
121		goto fail;
122	return acl;
123 fail:
124	posix_acl_release(acl);
125	return ERR_PTR(-EINVAL);
126}
127
128static void *jffs2_acl_to_medium(const struct posix_acl *acl, size_t *size)
129{
130	struct jffs2_acl_header *header;
131	struct jffs2_acl_entry *entry;
132	void *e;
133	size_t i;
134
135	*size = jffs2_acl_size(acl->a_count);
136	header = kmalloc(struct_size(header, a_entries, acl->a_count),
137			GFP_KERNEL);
138	if (!header)
139		return ERR_PTR(-ENOMEM);
140	header->a_version = cpu_to_je32(JFFS2_ACL_VERSION);
141	e = header + 1;
142	for (i=0; i < acl->a_count; i++) {
143		const struct posix_acl_entry *acl_e = &acl->a_entries[i];
144		entry = e;
145		entry->e_tag = cpu_to_je16(acl_e->e_tag);
146		entry->e_perm = cpu_to_je16(acl_e->e_perm);
147		switch(acl_e->e_tag) {
148			case ACL_USER:
149				entry->e_id = cpu_to_je32(
150					from_kuid(&init_user_ns, acl_e->e_uid));
151				e += sizeof(struct jffs2_acl_entry);
152				break;
153			case ACL_GROUP:
154				entry->e_id = cpu_to_je32(
155					from_kgid(&init_user_ns, acl_e->e_gid));
156				e += sizeof(struct jffs2_acl_entry);
157				break;
158
159			case ACL_USER_OBJ:
160			case ACL_GROUP_OBJ:
161			case ACL_MASK:
162			case ACL_OTHER:
163				e += sizeof(struct jffs2_acl_entry_short);
164				break;
165
166			default:
167				goto fail;
168		}
169	}
170	return header;
171 fail:
172	kfree(header);
173	return ERR_PTR(-EINVAL);
174}
175
176struct posix_acl *jffs2_get_acl(struct inode *inode, int type, bool rcu)
177{
178	struct posix_acl *acl;
179	char *value = NULL;
180	int rc, xprefix;
181
182	if (rcu)
183		return ERR_PTR(-ECHILD);
184
185	switch (type) {
186	case ACL_TYPE_ACCESS:
187		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
188		break;
189	case ACL_TYPE_DEFAULT:
190		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
191		break;
192	default:
193		BUG();
194	}
195	rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
196	if (rc > 0) {
197		value = kmalloc(rc, GFP_KERNEL);
198		if (!value)
199			return ERR_PTR(-ENOMEM);
200		rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
201	}
202	if (rc > 0) {
203		acl = jffs2_acl_from_medium(value, rc);
204	} else if (rc == -ENODATA || rc == -ENOSYS) {
205		acl = NULL;
206	} else {
207		acl = ERR_PTR(rc);
208	}
209	kfree(value);
210	return acl;
211}
212
213static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
214{
215	char *value = NULL;
216	size_t size = 0;
217	int rc;
218
219	if (acl) {
220		value = jffs2_acl_to_medium(acl, &size);
221		if (IS_ERR(value))
222			return PTR_ERR(value);
223	}
224	rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
225	if (!value && rc == -ENODATA)
226		rc = 0;
227	kfree(value);
228
229	return rc;
230}
231
232int jffs2_set_acl(struct user_namespace *mnt_userns, struct inode *inode,
233		  struct posix_acl *acl, int type)
234{
235	int rc, xprefix;
236
237	switch (type) {
238	case ACL_TYPE_ACCESS:
239		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
240		if (acl) {
241			umode_t mode;
242
243			rc = posix_acl_update_mode(&init_user_ns, inode, &mode,
244						   &acl);
245			if (rc)
246				return rc;
247			if (inode->i_mode != mode) {
248				struct iattr attr;
249
250				attr.ia_valid = ATTR_MODE | ATTR_CTIME;
251				attr.ia_mode = mode;
252				attr.ia_ctime = current_time(inode);
253				rc = jffs2_do_setattr(inode, &attr);
254				if (rc < 0)
255					return rc;
256			}
257		}
258		break;
259	case ACL_TYPE_DEFAULT:
260		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
261		if (!S_ISDIR(inode->i_mode))
262			return acl ? -EACCES : 0;
263		break;
264	default:
265		return -EINVAL;
266	}
267	rc = __jffs2_set_acl(inode, xprefix, acl);
268	if (!rc)
269		set_cached_acl(inode, type, acl);
270	return rc;
271}
272
273int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)
274{
275	struct posix_acl *default_acl, *acl;
276	int rc;
277
278	cache_no_acl(inode);
279
280	rc = posix_acl_create(dir_i, i_mode, &default_acl, &acl);
281	if (rc)
282		return rc;
283
284	if (default_acl) {
285		set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
286		posix_acl_release(default_acl);
287	}
288	if (acl) {
289		set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
290		posix_acl_release(acl);
291	}
292	return 0;
293}
294
295int jffs2_init_acl_post(struct inode *inode)
296{
297	int rc;
298
299	if (inode->i_default_acl) {
300		rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
301		if (rc)
302			return rc;
303	}
304
305	if (inode->i_acl) {
306		rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
307		if (rc)
308			return rc;
309	}
310
311	return 0;
312}
313