xref: /openbmc/linux/fs/jffs2/acl.c (revision b830f94f)
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 
26 static 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 
38 static 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 
55 static 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 
128 static 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 
176 struct posix_acl *jffs2_get_acl(struct inode *inode, int type)
177 {
178 	struct posix_acl *acl;
179 	char *value = NULL;
180 	int rc, xprefix;
181 
182 	switch (type) {
183 	case ACL_TYPE_ACCESS:
184 		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
185 		break;
186 	case ACL_TYPE_DEFAULT:
187 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
188 		break;
189 	default:
190 		BUG();
191 	}
192 	rc = do_jffs2_getxattr(inode, xprefix, "", NULL, 0);
193 	if (rc > 0) {
194 		value = kmalloc(rc, GFP_KERNEL);
195 		if (!value)
196 			return ERR_PTR(-ENOMEM);
197 		rc = do_jffs2_getxattr(inode, xprefix, "", value, rc);
198 	}
199 	if (rc > 0) {
200 		acl = jffs2_acl_from_medium(value, rc);
201 	} else if (rc == -ENODATA || rc == -ENOSYS) {
202 		acl = NULL;
203 	} else {
204 		acl = ERR_PTR(rc);
205 	}
206 	kfree(value);
207 	return acl;
208 }
209 
210 static int __jffs2_set_acl(struct inode *inode, int xprefix, struct posix_acl *acl)
211 {
212 	char *value = NULL;
213 	size_t size = 0;
214 	int rc;
215 
216 	if (acl) {
217 		value = jffs2_acl_to_medium(acl, &size);
218 		if (IS_ERR(value))
219 			return PTR_ERR(value);
220 	}
221 	rc = do_jffs2_setxattr(inode, xprefix, "", value, size, 0);
222 	if (!value && rc == -ENODATA)
223 		rc = 0;
224 	kfree(value);
225 
226 	return rc;
227 }
228 
229 int jffs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
230 {
231 	int rc, xprefix;
232 
233 	switch (type) {
234 	case ACL_TYPE_ACCESS:
235 		xprefix = JFFS2_XPREFIX_ACL_ACCESS;
236 		if (acl) {
237 			umode_t mode;
238 
239 			rc = posix_acl_update_mode(inode, &mode, &acl);
240 			if (rc)
241 				return rc;
242 			if (inode->i_mode != mode) {
243 				struct iattr attr;
244 
245 				attr.ia_valid = ATTR_MODE | ATTR_CTIME;
246 				attr.ia_mode = mode;
247 				attr.ia_ctime = current_time(inode);
248 				rc = jffs2_do_setattr(inode, &attr);
249 				if (rc < 0)
250 					return rc;
251 			}
252 		}
253 		break;
254 	case ACL_TYPE_DEFAULT:
255 		xprefix = JFFS2_XPREFIX_ACL_DEFAULT;
256 		if (!S_ISDIR(inode->i_mode))
257 			return acl ? -EACCES : 0;
258 		break;
259 	default:
260 		return -EINVAL;
261 	}
262 	rc = __jffs2_set_acl(inode, xprefix, acl);
263 	if (!rc)
264 		set_cached_acl(inode, type, acl);
265 	return rc;
266 }
267 
268 int jffs2_init_acl_pre(struct inode *dir_i, struct inode *inode, umode_t *i_mode)
269 {
270 	struct posix_acl *default_acl, *acl;
271 	int rc;
272 
273 	cache_no_acl(inode);
274 
275 	rc = posix_acl_create(dir_i, i_mode, &default_acl, &acl);
276 	if (rc)
277 		return rc;
278 
279 	if (default_acl) {
280 		set_cached_acl(inode, ACL_TYPE_DEFAULT, default_acl);
281 		posix_acl_release(default_acl);
282 	}
283 	if (acl) {
284 		set_cached_acl(inode, ACL_TYPE_ACCESS, acl);
285 		posix_acl_release(acl);
286 	}
287 	return 0;
288 }
289 
290 int jffs2_init_acl_post(struct inode *inode)
291 {
292 	int rc;
293 
294 	if (inode->i_default_acl) {
295 		rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_DEFAULT, inode->i_default_acl);
296 		if (rc)
297 			return rc;
298 	}
299 
300 	if (inode->i_acl) {
301 		rc = __jffs2_set_acl(inode, JFFS2_XPREFIX_ACL_ACCESS, inode->i_acl);
302 		if (rc)
303 			return rc;
304 	}
305 
306 	return 0;
307 }
308