1 /*
2 * fs/sysfs/inode.c - basic sysfs inode and dentry operations
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007 Tejun Heo <teheo@suse.de>
7 *
8 * This file is released under the GPLv2.
9 *
10 * Please see Documentation/filesystems/sysfs.txt for more information.
11 */
12
13 #undef DEBUG
14
15 #include <linux/pagemap.h>
16 #include <linux/namei.h>
17 #include <linux/backing-dev.h>
18 #include <linux/capability.h>
19 #include <linux/errno.h>
20 #include <linux/sched.h>
21 #include <linux/slab.h>
22 #include <linux/sysfs.h>
23 #include <linux/xattr.h>
24 #include <linux/security.h>
25 #include "sysfs.h"
26
27 extern struct super_block * sysfs_sb;
28
29 static const struct address_space_operations sysfs_aops = {
30 .readpage = simple_readpage,
31 .write_begin = simple_write_begin,
32 .write_end = simple_write_end,
33 };
34
35 static struct backing_dev_info sysfs_backing_dev_info = {
36 .name = "sysfs",
37 .ra_pages = 0, /* No readahead */
38 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
39 };
40
41 static const struct inode_operations sysfs_inode_operations ={
42 .permission = sysfs_permission,
43 .setattr = sysfs_setattr,
44 .getattr = sysfs_getattr,
45 .setxattr = sysfs_setxattr,
46 };
47
sysfs_inode_init(void)48 int __init sysfs_inode_init(void)
49 {
50 return bdi_init(&sysfs_backing_dev_info);
51 }
52
sysfs_init_inode_attrs(struct sysfs_dirent * sd)53 static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
54 {
55 struct sysfs_inode_attrs *attrs;
56 struct iattr *iattrs;
57
58 attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
59 if (!attrs)
60 return NULL;
61 iattrs = &attrs->ia_iattr;
62
63 /* assign default attributes */
64 iattrs->ia_mode = sd->s_mode;
65 iattrs->ia_uid = 0;
66 iattrs->ia_gid = 0;
67 iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
68
69 return attrs;
70 }
71
sysfs_sd_setattr(struct sysfs_dirent * sd,struct iattr * iattr)72 int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr * iattr)
73 {
74 struct sysfs_inode_attrs *sd_attrs;
75 struct iattr *iattrs;
76 unsigned int ia_valid = iattr->ia_valid;
77
78 sd_attrs = sd->s_iattr;
79
80 if (!sd_attrs) {
81 /* setting attributes for the first time, allocate now */
82 sd_attrs = sysfs_init_inode_attrs(sd);
83 if (!sd_attrs)
84 return -ENOMEM;
85 sd->s_iattr = sd_attrs;
86 }
87 /* attributes were changed at least once in past */
88 iattrs = &sd_attrs->ia_iattr;
89
90 if (ia_valid & ATTR_UID)
91 iattrs->ia_uid = iattr->ia_uid;
92 if (ia_valid & ATTR_GID)
93 iattrs->ia_gid = iattr->ia_gid;
94 if (ia_valid & ATTR_ATIME)
95 iattrs->ia_atime = iattr->ia_atime;
96 if (ia_valid & ATTR_MTIME)
97 iattrs->ia_mtime = iattr->ia_mtime;
98 if (ia_valid & ATTR_CTIME)
99 iattrs->ia_ctime = iattr->ia_ctime;
100 if (ia_valid & ATTR_MODE) {
101 umode_t mode = iattr->ia_mode;
102 iattrs->ia_mode = sd->s_mode = mode;
103 }
104 return 0;
105 }
106
sysfs_setattr(struct dentry * dentry,struct iattr * iattr)107 int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
108 {
109 struct inode *inode = dentry->d_inode;
110 struct sysfs_dirent *sd = dentry->d_fsdata;
111 int error;
112
113 if (!sd)
114 return -EINVAL;
115
116 mutex_lock(&sysfs_mutex);
117 error = inode_change_ok(inode, iattr);
118 if (error)
119 goto out;
120
121 error = sysfs_sd_setattr(sd, iattr);
122 if (error)
123 goto out;
124
125 /* this ignores size changes */
126 setattr_copy(inode, iattr);
127
128 out:
129 mutex_unlock(&sysfs_mutex);
130 return error;
131 }
132
sysfs_sd_setsecdata(struct sysfs_dirent * sd,void ** secdata,u32 * secdata_len)133 static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata, u32 *secdata_len)
134 {
135 struct sysfs_inode_attrs *iattrs;
136 void *old_secdata;
137 size_t old_secdata_len;
138
139 if (!sd->s_iattr) {
140 sd->s_iattr = sysfs_init_inode_attrs(sd);
141 if (!sd->s_iattr)
142 return -ENOMEM;
143 }
144
145 iattrs = sd->s_iattr;
146 old_secdata = iattrs->ia_secdata;
147 old_secdata_len = iattrs->ia_secdata_len;
148
149 iattrs->ia_secdata = *secdata;
150 iattrs->ia_secdata_len = *secdata_len;
151
152 *secdata = old_secdata;
153 *secdata_len = old_secdata_len;
154 return 0;
155 }
156
sysfs_setxattr(struct dentry * dentry,const char * name,const void * value,size_t size,int flags)157 int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
158 size_t size, int flags)
159 {
160 struct sysfs_dirent *sd = dentry->d_fsdata;
161 void *secdata;
162 int error;
163 u32 secdata_len = 0;
164
165 if (!sd)
166 return -EINVAL;
167
168 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
169 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
170 error = security_inode_setsecurity(dentry->d_inode, suffix,
171 value, size, flags);
172 if (error)
173 goto out;
174 error = security_inode_getsecctx(dentry->d_inode,
175 &secdata, &secdata_len);
176 if (error)
177 goto out;
178
179 mutex_lock(&sysfs_mutex);
180 error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
181 mutex_unlock(&sysfs_mutex);
182
183 if (secdata)
184 security_release_secctx(secdata, secdata_len);
185 } else
186 return -EINVAL;
187 out:
188 return error;
189 }
190
set_default_inode_attr(struct inode * inode,umode_t mode)191 static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
192 {
193 inode->i_mode = mode;
194 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
195 }
196
set_inode_attr(struct inode * inode,struct iattr * iattr)197 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
198 {
199 inode->i_uid = iattr->ia_uid;
200 inode->i_gid = iattr->ia_gid;
201 inode->i_atime = iattr->ia_atime;
202 inode->i_mtime = iattr->ia_mtime;
203 inode->i_ctime = iattr->ia_ctime;
204 }
205
sysfs_refresh_inode(struct sysfs_dirent * sd,struct inode * inode)206 static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
207 {
208 struct sysfs_inode_attrs *iattrs = sd->s_iattr;
209
210 inode->i_mode = sd->s_mode;
211 if (iattrs) {
212 /* sysfs_dirent has non-default attributes
213 * get them from persistent copy in sysfs_dirent
214 */
215 set_inode_attr(inode, &iattrs->ia_iattr);
216 security_inode_notifysecctx(inode,
217 iattrs->ia_secdata,
218 iattrs->ia_secdata_len);
219 }
220
221 if (sysfs_type(sd) == SYSFS_DIR)
222 set_nlink(inode, sd->s_dir.subdirs + 2);
223 }
224
sysfs_getattr(struct vfsmount * mnt,struct dentry * dentry,struct kstat * stat)225 int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
226 {
227 struct sysfs_dirent *sd = dentry->d_fsdata;
228 struct inode *inode = dentry->d_inode;
229
230 mutex_lock(&sysfs_mutex);
231 sysfs_refresh_inode(sd, inode);
232 mutex_unlock(&sysfs_mutex);
233
234 generic_fillattr(inode, stat);
235 return 0;
236 }
237
sysfs_init_inode(struct sysfs_dirent * sd,struct inode * inode)238 static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
239 {
240 struct bin_attribute *bin_attr;
241
242 inode->i_private = sysfs_get(sd);
243 inode->i_mapping->a_ops = &sysfs_aops;
244 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
245 inode->i_op = &sysfs_inode_operations;
246
247 set_default_inode_attr(inode, sd->s_mode);
248 sysfs_refresh_inode(sd, inode);
249
250 /* initialize inode according to type */
251 switch (sysfs_type(sd)) {
252 case SYSFS_DIR:
253 inode->i_op = &sysfs_dir_inode_operations;
254 inode->i_fop = &sysfs_dir_operations;
255 break;
256 case SYSFS_KOBJ_ATTR:
257 inode->i_size = PAGE_SIZE;
258 inode->i_fop = &sysfs_file_operations;
259 break;
260 case SYSFS_KOBJ_BIN_ATTR:
261 bin_attr = sd->s_bin_attr.bin_attr;
262 inode->i_size = bin_attr->size;
263 inode->i_fop = &bin_fops;
264 break;
265 case SYSFS_KOBJ_LINK:
266 inode->i_op = &sysfs_symlink_inode_operations;
267 break;
268 default:
269 BUG();
270 }
271
272 unlock_new_inode(inode);
273 }
274
275 /**
276 * sysfs_get_inode - get inode for sysfs_dirent
277 * @sb: super block
278 * @sd: sysfs_dirent to allocate inode for
279 *
280 * Get inode for @sd. If such inode doesn't exist, a new inode
281 * is allocated and basics are initialized. New inode is
282 * returned locked.
283 *
284 * LOCKING:
285 * Kernel thread context (may sleep).
286 *
287 * RETURNS:
288 * Pointer to allocated inode on success, NULL on failure.
289 */
sysfs_get_inode(struct super_block * sb,struct sysfs_dirent * sd)290 struct inode * sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
291 {
292 struct inode *inode;
293
294 inode = iget_locked(sb, sd->s_ino);
295 if (inode && (inode->i_state & I_NEW))
296 sysfs_init_inode(sd, inode);
297
298 return inode;
299 }
300
301 /*
302 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
303 * To prevent the sysfs inode numbers from being freed prematurely we take a
304 * reference to sysfs_dirent from the sysfs inode. A
305 * super_operations.evict_inode() implementation is needed to drop that
306 * reference upon inode destruction.
307 */
sysfs_evict_inode(struct inode * inode)308 void sysfs_evict_inode(struct inode *inode)
309 {
310 struct sysfs_dirent *sd = inode->i_private;
311
312 truncate_inode_pages(&inode->i_data, 0);
313 end_writeback(inode);
314 sysfs_put(sd);
315 }
316
sysfs_hash_and_remove(struct sysfs_dirent * dir_sd,const void * ns,const char * name)317 int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const void *ns, const char *name)
318 {
319 struct sysfs_addrm_cxt acxt;
320 struct sysfs_dirent *sd;
321
322 if (!dir_sd) {
323 WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n",
324 name);
325 return -ENOENT;
326 }
327
328 sysfs_addrm_start(&acxt, dir_sd);
329
330 sd = sysfs_find_dirent(dir_sd, ns, name);
331 if (sd)
332 sysfs_remove_one(&acxt, sd);
333
334 sysfs_addrm_finish(&acxt);
335
336 if (sd)
337 return 0;
338 else
339 return -ENOENT;
340 }
341
sysfs_permission(struct inode * inode,int mask)342 int sysfs_permission(struct inode *inode, int mask)
343 {
344 struct sysfs_dirent *sd;
345
346 if (mask & MAY_NOT_BLOCK)
347 return -ECHILD;
348
349 sd = inode->i_private;
350
351 mutex_lock(&sysfs_mutex);
352 sysfs_refresh_inode(sd, inode);
353 mutex_unlock(&sysfs_mutex);
354
355 return generic_permission(inode, mask);
356 }
357