inode.c (b8441ed279bff09a0a5ddeacf8f4087d2fb424ca) inode.c (ffed24e22845a3da0ae01095ae3f11c8d16e889d)
1/*
2 * fs/kernfs/inode.c - kernfs inode implementation
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
7 *
8 * This file is released under the GPLv2.
9 */
1/*
2 * fs/kernfs/inode.c - kernfs inode implementation
3 *
4 * Copyright (c) 2001-3 Patrick Mochel
5 * Copyright (c) 2007 SUSE Linux Products GmbH
6 * Copyright (c) 2007, 2013 Tejun Heo <tj@kernel.org>
7 *
8 * This file is released under the GPLv2.
9 */
10
11#include <linux/pagemap.h>
12#include <linux/backing-dev.h>
13#include <linux/capability.h>
14#include <linux/errno.h>
15#include <linux/slab.h>
16#include <linux/xattr.h>
17#include <linux/security.h>
18
19#include "kernfs-internal.h"
20
21static const struct address_space_operations sysfs_aops = {
22 .readpage = simple_readpage,
23 .write_begin = simple_write_begin,
24 .write_end = simple_write_end,
25};
26
27static struct backing_dev_info sysfs_backing_dev_info = {
28 .name = "sysfs",
29 .ra_pages = 0, /* No readahead */
30 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
31};
32
33static const struct inode_operations sysfs_inode_operations = {
34 .permission = sysfs_permission,
35 .setattr = sysfs_setattr,
36 .getattr = sysfs_getattr,
37 .setxattr = sysfs_setxattr,
38};
39
40int __init sysfs_inode_init(void)
41{
42 return bdi_init(&sysfs_backing_dev_info);
43}
44
45static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
46{
47 struct sysfs_inode_attrs *attrs;
48 struct iattr *iattrs;
49
50 attrs = kzalloc(sizeof(struct sysfs_inode_attrs), GFP_KERNEL);
51 if (!attrs)
52 return NULL;
53 iattrs = &attrs->ia_iattr;
54
55 /* assign default attributes */
56 iattrs->ia_mode = sd->s_mode;
57 iattrs->ia_uid = GLOBAL_ROOT_UID;
58 iattrs->ia_gid = GLOBAL_ROOT_GID;
59 iattrs->ia_atime = iattrs->ia_mtime = iattrs->ia_ctime = CURRENT_TIME;
60
61 return attrs;
62}
63
64static int __kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
65{
66 struct sysfs_inode_attrs *sd_attrs;
67 struct iattr *iattrs;
68 unsigned int ia_valid = iattr->ia_valid;
69
70 sd_attrs = sd->s_iattr;
71
72 if (!sd_attrs) {
73 /* setting attributes for the first time, allocate now */
74 sd_attrs = sysfs_init_inode_attrs(sd);
75 if (!sd_attrs)
76 return -ENOMEM;
77 sd->s_iattr = sd_attrs;
78 }
79 /* attributes were changed at least once in past */
80 iattrs = &sd_attrs->ia_iattr;
81
82 if (ia_valid & ATTR_UID)
83 iattrs->ia_uid = iattr->ia_uid;
84 if (ia_valid & ATTR_GID)
85 iattrs->ia_gid = iattr->ia_gid;
86 if (ia_valid & ATTR_ATIME)
87 iattrs->ia_atime = iattr->ia_atime;
88 if (ia_valid & ATTR_MTIME)
89 iattrs->ia_mtime = iattr->ia_mtime;
90 if (ia_valid & ATTR_CTIME)
91 iattrs->ia_ctime = iattr->ia_ctime;
92 if (ia_valid & ATTR_MODE) {
93 umode_t mode = iattr->ia_mode;
94 iattrs->ia_mode = sd->s_mode = mode;
95 }
96 return 0;
97}
98
99/**
100 * kernfs_setattr - set iattr on a node
101 * @sd: target node
102 * @iattr: iattr to set
103 *
104 * Returns 0 on success, -errno on failure.
105 */
106int kernfs_setattr(struct sysfs_dirent *sd, const struct iattr *iattr)
107{
108 int ret;
109
110 mutex_lock(&sysfs_mutex);
111 ret = __kernfs_setattr(sd, iattr);
112 mutex_unlock(&sysfs_mutex);
113 return ret;
114}
115
116int sysfs_setattr(struct dentry *dentry, struct iattr *iattr)
117{
118 struct inode *inode = dentry->d_inode;
119 struct sysfs_dirent *sd = dentry->d_fsdata;
120 int error;
121
122 if (!sd)
123 return -EINVAL;
124
125 mutex_lock(&sysfs_mutex);
126 error = inode_change_ok(inode, iattr);
127 if (error)
128 goto out;
129
130 error = __kernfs_setattr(sd, iattr);
131 if (error)
132 goto out;
133
134 /* this ignores size changes */
135 setattr_copy(inode, iattr);
136
137out:
138 mutex_unlock(&sysfs_mutex);
139 return error;
140}
141
142static int sysfs_sd_setsecdata(struct sysfs_dirent *sd, void **secdata,
143 u32 *secdata_len)
144{
145 struct sysfs_inode_attrs *iattrs;
146 void *old_secdata;
147 size_t old_secdata_len;
148
149 if (!sd->s_iattr) {
150 sd->s_iattr = sysfs_init_inode_attrs(sd);
151 if (!sd->s_iattr)
152 return -ENOMEM;
153 }
154
155 iattrs = sd->s_iattr;
156 old_secdata = iattrs->ia_secdata;
157 old_secdata_len = iattrs->ia_secdata_len;
158
159 iattrs->ia_secdata = *secdata;
160 iattrs->ia_secdata_len = *secdata_len;
161
162 *secdata = old_secdata;
163 *secdata_len = old_secdata_len;
164 return 0;
165}
166
167int sysfs_setxattr(struct dentry *dentry, const char *name, const void *value,
168 size_t size, int flags)
169{
170 struct sysfs_dirent *sd = dentry->d_fsdata;
171 void *secdata;
172 int error;
173 u32 secdata_len = 0;
174
175 if (!sd)
176 return -EINVAL;
177
178 if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN)) {
179 const char *suffix = name + XATTR_SECURITY_PREFIX_LEN;
180 error = security_inode_setsecurity(dentry->d_inode, suffix,
181 value, size, flags);
182 if (error)
183 goto out;
184 error = security_inode_getsecctx(dentry->d_inode,
185 &secdata, &secdata_len);
186 if (error)
187 goto out;
188
189 mutex_lock(&sysfs_mutex);
190 error = sysfs_sd_setsecdata(sd, &secdata, &secdata_len);
191 mutex_unlock(&sysfs_mutex);
192
193 if (secdata)
194 security_release_secctx(secdata, secdata_len);
195 } else
196 return -EINVAL;
197out:
198 return error;
199}
200
201static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
202{
203 inode->i_mode = mode;
204 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
205}
206
207static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
208{
209 inode->i_uid = iattr->ia_uid;
210 inode->i_gid = iattr->ia_gid;
211 inode->i_atime = iattr->ia_atime;
212 inode->i_mtime = iattr->ia_mtime;
213 inode->i_ctime = iattr->ia_ctime;
214}
215
216static void sysfs_refresh_inode(struct sysfs_dirent *sd, struct inode *inode)
217{
218 struct sysfs_inode_attrs *iattrs = sd->s_iattr;
219
220 inode->i_mode = sd->s_mode;
221 if (iattrs) {
222 /* sysfs_dirent has non-default attributes
223 * get them from persistent copy in sysfs_dirent
224 */
225 set_inode_attr(inode, &iattrs->ia_iattr);
226 security_inode_notifysecctx(inode,
227 iattrs->ia_secdata,
228 iattrs->ia_secdata_len);
229 }
230
231 if (sysfs_type(sd) == SYSFS_DIR)
232 set_nlink(inode, sd->s_dir.subdirs + 2);
233}
234
235int sysfs_getattr(struct vfsmount *mnt, struct dentry *dentry,
236 struct kstat *stat)
237{
238 struct sysfs_dirent *sd = dentry->d_fsdata;
239 struct inode *inode = dentry->d_inode;
240
241 mutex_lock(&sysfs_mutex);
242 sysfs_refresh_inode(sd, inode);
243 mutex_unlock(&sysfs_mutex);
244
245 generic_fillattr(inode, stat);
246 return 0;
247}
248
249static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
250{
251 kernfs_get(sd);
252 inode->i_private = sd;
253 inode->i_mapping->a_ops = &sysfs_aops;
254 inode->i_mapping->backing_dev_info = &sysfs_backing_dev_info;
255 inode->i_op = &sysfs_inode_operations;
256
257 set_default_inode_attr(inode, sd->s_mode);
258 sysfs_refresh_inode(sd, inode);
259
260 /* initialize inode according to type */
261 switch (sysfs_type(sd)) {
262 case SYSFS_DIR:
263 inode->i_op = &sysfs_dir_inode_operations;
264 inode->i_fop = &sysfs_dir_operations;
265 break;
266 case SYSFS_KOBJ_ATTR:
267 inode->i_size = sd->s_attr.size;
268 inode->i_fop = &kernfs_file_operations;
269 break;
270 case SYSFS_KOBJ_LINK:
271 inode->i_op = &sysfs_symlink_inode_operations;
272 break;
273 default:
274 BUG();
275 }
276
277 unlock_new_inode(inode);
278}
279
280/**
281 * sysfs_get_inode - get inode for sysfs_dirent
282 * @sb: super block
283 * @sd: sysfs_dirent to allocate inode for
284 *
285 * Get inode for @sd. If such inode doesn't exist, a new inode
286 * is allocated and basics are initialized. New inode is
287 * returned locked.
288 *
289 * LOCKING:
290 * Kernel thread context (may sleep).
291 *
292 * RETURNS:
293 * Pointer to allocated inode on success, NULL on failure.
294 */
295struct inode *sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
296{
297 struct inode *inode;
298
299 inode = iget_locked(sb, sd->s_ino);
300 if (inode && (inode->i_state & I_NEW))
301 sysfs_init_inode(sd, inode);
302
303 return inode;
304}
305
306/*
307 * The sysfs_dirent serves as both an inode and a directory entry for sysfs.
308 * To prevent the sysfs inode numbers from being freed prematurely we take a
309 * reference to sysfs_dirent from the sysfs inode. A
310 * super_operations.evict_inode() implementation is needed to drop that
311 * reference upon inode destruction.
312 */
313void sysfs_evict_inode(struct inode *inode)
314{
315 struct sysfs_dirent *sd = inode->i_private;
316
317 truncate_inode_pages(&inode->i_data, 0);
318 clear_inode(inode);
319 kernfs_put(sd);
320}
321
322int sysfs_permission(struct inode *inode, int mask)
323{
324 struct sysfs_dirent *sd;
325
326 if (mask & MAY_NOT_BLOCK)
327 return -ECHILD;
328
329 sd = inode->i_private;
330
331 mutex_lock(&sysfs_mutex);
332 sysfs_refresh_inode(sd, inode);
333 mutex_unlock(&sysfs_mutex);
334
335 return generic_permission(inode, mask);
336}