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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
Tejun Heo6d66f5c2007-09-20 17:31:38 +09002 * fs/sysfs/inode.c - basic sysfs inode and dentry operations
Linus Torvalds1da177e2005-04-16 15:20:36 -07003 *
Tejun Heo6d66f5c2007-09-20 17:31:38 +09004 * 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.
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 *
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>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080018#include <linux/capability.h>
Randy.Dunlap995982c2006-07-10 23:05:25 -070019#include <linux/errno.h>
Alexey Dobriyane8edc6e2007-05-21 01:22:52 +040020#include <linux/sched.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090021#include <linux/slab.h>
Alexey Dobriyan57cc7212011-01-10 08:18:25 +020022#include <linux/sysfs.h>
David P. Quigleyddd29ec2009-09-09 14:25:37 -040023#include <linux/xattr.h>
24#include <linux/security.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include "sysfs.h"
26
27extern struct super_block * sysfs_sb;
28
Christoph Hellwigf5e54d62006-06-28 04:26:44 -070029static const struct address_space_operations sysfs_aops = {
Linus Torvalds1da177e2005-04-16 15:20:36 -070030 .readpage = simple_readpage,
Nick Piggin800d15a2007-10-16 01:25:03 -070031 .write_begin = simple_write_begin,
32 .write_end = simple_write_end,
Linus Torvalds1da177e2005-04-16 15:20:36 -070033};
34
35static struct backing_dev_info sysfs_backing_dev_info = {
Jens Axboed9938312009-06-12 14:45:52 +020036 .name = "sysfs",
Linus Torvalds1da177e2005-04-16 15:20:36 -070037 .ra_pages = 0, /* No readahead */
Miklos Szeredie4ad08f2008-04-30 00:54:37 -070038 .capabilities = BDI_CAP_NO_ACCT_AND_WRITEBACK,
Linus Torvalds1da177e2005-04-16 15:20:36 -070039};
40
Arjan van de Venc5ef1c42007-02-12 00:55:40 -080041static const struct inode_operations sysfs_inode_operations ={
Eric W. Biedermane61ab4a2009-11-20 16:08:53 -080042 .permission = sysfs_permission,
Maneesh Soni988d1862005-05-31 10:39:14 +053043 .setattr = sysfs_setattr,
Eric W. Biedermane61ab4a2009-11-20 16:08:53 -080044 .getattr = sysfs_getattr,
David P. Quigleyddd29ec2009-09-09 14:25:37 -040045 .setxattr = sysfs_setxattr,
Maneesh Soni988d1862005-05-31 10:39:14 +053046};
47
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -070048int __init sysfs_inode_init(void)
49{
50 return bdi_init(&sysfs_backing_dev_info);
51}
52
Stefan Richterf38506c2009-10-14 20:47:32 +020053static struct sysfs_inode_attrs *sysfs_init_inode_attrs(struct sysfs_dirent *sd)
David P. Quigleyddd29ec2009-09-09 14:25:37 -040054{
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}
Stefan Richterf38506c2009-10-14 20:47:32 +020071
Eric W. Biederman35df63c2009-11-20 16:08:50 -080072int sysfs_sd_setattr(struct sysfs_dirent *sd, struct iattr * iattr)
Maneesh Soni988d1862005-05-31 10:39:14 +053073{
David P. Quigleyddd29ec2009-09-09 14:25:37 -040074 struct sysfs_inode_attrs *sd_attrs;
75 struct iattr *iattrs;
Maneesh Soni988d1862005-05-31 10:39:14 +053076 unsigned int ia_valid = iattr->ia_valid;
Maneesh Soni988d1862005-05-31 10:39:14 +053077
David P. Quigleyddd29ec2009-09-09 14:25:37 -040078 sd_attrs = sd->s_iattr;
Maneesh Soni988d1862005-05-31 10:39:14 +053079
David P. Quigleyddd29ec2009-09-09 14:25:37 -040080 if (!sd_attrs) {
Maneesh Soni988d1862005-05-31 10:39:14 +053081 /* setting attributes for the first time, allocate now */
David P. Quigleyddd29ec2009-09-09 14:25:37 -040082 sd_attrs = sysfs_init_inode_attrs(sd);
83 if (!sd_attrs)
Maneesh Soni988d1862005-05-31 10:39:14 +053084 return -ENOMEM;
David P. Quigleyddd29ec2009-09-09 14:25:37 -040085 sd->s_iattr = sd_attrs;
Eric W. Biederman7c0ff872010-02-03 23:13:24 -080086 }
87 /* attributes were changed at least once in past */
88 iattrs = &sd_attrs->ia_iattr;
David P. Quigleyddd29ec2009-09-09 14:25:37 -040089
Eric W. Biederman7c0ff872010-02-03 23:13:24 -080090 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;
Maneesh Soni988d1862005-05-31 10:39:14 +0530103 }
Eric W. Biederman35df63c2009-11-20 16:08:50 -0800104 return 0;
105}
106
107int 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
Eric W. Biedermanf8d4f612010-02-12 19:22:23 -0800116 mutex_lock(&sysfs_mutex);
Eric W. Biederman35df63c2009-11-20 16:08:50 -0800117 error = inode_change_ok(inode, iattr);
118 if (error)
Eric W. Biedermanf8d4f612010-02-12 19:22:23 -0800119 goto out;
Eric W. Biederman35df63c2009-11-20 16:08:50 -0800120
Nick Piggin75de46b2010-05-31 17:58:02 +1000121 error = sysfs_sd_setattr(sd, iattr);
122 if (error)
123 goto out;
124
Nick Piggin3322e792010-05-27 22:42:19 +1000125 /* this ignores size changes */
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200126 setattr_copy(inode, iattr);
Eric W. Biederman35df63c2009-11-20 16:08:50 -0800127
Eric W. Biedermanf8d4f612010-02-12 19:22:23 -0800128out:
Eric W. Biederman35df63c2009-11-20 16:08:50 -0800129 mutex_unlock(&sysfs_mutex);
David P. Quigleyddd29ec2009-09-09 14:25:37 -0400130 return error;
131}
Maneesh Soni988d1862005-05-31 10:39:14 +0530132
Eric W. Biedermanf44d3e72009-11-07 23:26:59 -0800133static 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
Masami Ichikawa93518dd2012-02-21 07:43:50 +0900139 if (!sd->s_iattr) {
140 sd->s_iattr = sysfs_init_inode_attrs(sd);
141 if (!sd->s_iattr)
142 return -ENOMEM;
143 }
Eric W. Biedermanf44d3e72009-11-07 23:26:59 -0800144
Masami Ichikawa93518dd2012-02-21 07:43:50 +0900145 iattrs = sd->s_iattr;
Eric W. Biedermanf44d3e72009-11-07 23:26:59 -0800146 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
David P. Quigleyddd29ec2009-09-09 14:25:37 -0400157int 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;
David P. Quigleyddd29ec2009-09-09 14:25:37 -0400161 void *secdata;
162 int error;
163 u32 secdata_len = 0;
Maneesh Soni988d1862005-05-31 10:39:14 +0530164
David P. Quigleyddd29ec2009-09-09 14:25:37 -0400165 if (!sd)
166 return -EINVAL;
Maneesh Soni988d1862005-05-31 10:39:14 +0530167
David P. Quigleyddd29ec2009-09-09 14:25:37 -0400168 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;
David P. Quigleyddd29ec2009-09-09 14:25:37 -0400178
Eric W. Biedermanf44d3e72009-11-07 23:26:59 -0800179 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);
David P. Quigleyddd29ec2009-09-09 14:25:37 -0400185 } else
186 return -EINVAL;
187out:
Maneesh Soni988d1862005-05-31 10:39:14 +0530188 return error;
189}
190
Al Virofaef2b62011-07-24 23:44:53 -0400191static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
Maneesh Soni82155342005-05-31 10:39:52 +0530192{
193 inode->i_mode = mode;
Maneesh Soni82155342005-05-31 10:39:52 +0530194 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
195}
196
197static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
198{
Maneesh Soni82155342005-05-31 10:39:52 +0530199 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
Eric W. Biedermane61ab4a2009-11-20 16:08:53 -0800206static 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 }
Greg Kroah-Hartman54d20f02012-03-08 13:03:10 -0800220
221 if (sysfs_type(sd) == SYSFS_DIR)
222 set_nlink(inode, sd->s_dir.subdirs + 2);
Eric W. Biedermane61ab4a2009-11-20 16:08:53 -0800223}
224
225int 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
Tejun Heobc37e282007-07-18 14:30:28 +0900238static void sysfs_init_inode(struct sysfs_dirent *sd, struct inode *inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239{
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900240 struct bin_attribute *bin_attr;
241
Eric W. Biederman04256b42009-02-11 13:20:23 -0800242 inode->i_private = sysfs_get(sd);
Tejun Heofc9f54b2007-06-14 03:45:17 +0900243 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;
Maneesh Soni82155342005-05-31 10:39:52 +0530246
Eric W. Biedermane61ab4a2009-11-20 16:08:53 -0800247 set_default_inode_attr(inode, sd->s_mode);
248 sysfs_refresh_inode(sd, inode);
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900249
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900250 /* initialize inode according to type */
251 switch (sysfs_type(sd)) {
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900252 case SYSFS_DIR:
253 inode->i_op = &sysfs_dir_inode_operations;
254 inode->i_fop = &sysfs_dir_operations;
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900255 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:
Tejun Heob1fc3d62007-09-20 16:05:11 +0900261 bin_attr = sd->s_bin_attr.bin_attr;
Eric W. Biederman372e88b2007-08-20 21:36:29 +0900262 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);
Tejun Heofc9f54b2007-06-14 03:45:17 +0900273}
274
275/**
Tejun Heo8312a8d2007-06-14 03:45:17 +0900276 * sysfs_get_inode - get inode for sysfs_dirent
Eric W. Biedermanfac26222010-02-12 19:22:27 -0800277 * @sb: super block
Tejun Heofc9f54b2007-06-14 03:45:17 +0900278 * @sd: sysfs_dirent to allocate inode for
279 *
Tejun Heo8312a8d2007-06-14 03:45:17 +0900280 * 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.
Tejun Heofc9f54b2007-06-14 03:45:17 +0900283 *
284 * LOCKING:
285 * Kernel thread context (may sleep).
286 *
287 * RETURNS:
288 * Pointer to allocated inode on success, NULL on failure.
289 */
Eric W. Biedermanfac26222010-02-12 19:22:27 -0800290struct inode * sysfs_get_inode(struct super_block *sb, struct sysfs_dirent *sd)
Tejun Heofc9f54b2007-06-14 03:45:17 +0900291{
292 struct inode *inode;
293
Eric W. Biedermanfac26222010-02-12 19:22:27 -0800294 inode = iget_locked(sb, sd->s_ino);
Tejun Heo8312a8d2007-06-14 03:45:17 +0900295 if (inode && (inode->i_state & I_NEW))
Tejun Heofc9f54b2007-06-14 03:45:17 +0900296 sysfs_init_inode(sd, inode);
297
Linus Torvalds1da177e2005-04-16 15:20:36 -0700298 return inode;
299}
300
Eric W. Biederman04256b42009-02-11 13:20:23 -0800301/*
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
Al Viro01cd9fe2010-06-04 22:21:54 -0400305 * super_operations.evict_inode() implementation is needed to drop that
Eric W. Biederman04256b42009-02-11 13:20:23 -0800306 * reference upon inode destruction.
307 */
Al Viro01cd9fe2010-06-04 22:21:54 -0400308void sysfs_evict_inode(struct inode *inode)
Eric W. Biederman04256b42009-02-11 13:20:23 -0800309{
310 struct sysfs_dirent *sd = inode->i_private;
311
312 truncate_inode_pages(&inode->i_data, 0);
Al Viro01cd9fe2010-06-04 22:21:54 -0400313 end_writeback(inode);
Eric W. Biederman04256b42009-02-11 13:20:23 -0800314 sysfs_put(sd);
315}
316
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700317int sysfs_hash_and_remove(struct sysfs_dirent *dir_sd, const void *ns, const char *name)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700318{
Tejun Heofb6896d2007-06-14 04:27:24 +0900319 struct sysfs_addrm_cxt acxt;
Tejun Heo41fc1c22007-08-02 21:38:03 +0900320 struct sysfs_dirent *sd;
Greg Kroah-Hartman641e6f32006-03-16 15:44:26 -0800321
Eric W. Biedermance597912012-01-13 21:32:59 -0800322 if (!dir_sd) {
323 WARN(1, KERN_WARNING "sysfs: can not remove '%s', no directory\n",
324 name);
Randy.Dunlap995982c2006-07-10 23:05:25 -0700325 return -ENOENT;
Eric W. Biedermance597912012-01-13 21:32:59 -0800326 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327
Tejun Heofb6896d2007-06-14 04:27:24 +0900328 sysfs_addrm_start(&acxt, dir_sd);
Tejun Heo608e2662007-06-14 04:27:22 +0900329
Eric W. Biederman3ff195b2010-03-30 11:31:26 -0700330 sd = sysfs_find_dirent(dir_sd, ns, name);
Tejun Heo41fc1c22007-08-02 21:38:03 +0900331 if (sd)
332 sysfs_remove_one(&acxt, sd);
Tejun Heo3007e992007-06-14 04:27:23 +0900333
Tejun Heo990e53f2007-08-02 21:38:03 +0900334 sysfs_addrm_finish(&acxt);
335
336 if (sd)
Tejun Heofb6896d2007-06-14 04:27:24 +0900337 return 0;
Tejun Heo990e53f2007-08-02 21:38:03 +0900338 else
339 return -ENOENT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340}
Eric W. Biedermane61ab4a2009-11-20 16:08:53 -0800341
Al Viro10556cb2011-06-20 19:28:19 -0400342int sysfs_permission(struct inode *inode, int mask)
Eric W. Biedermane61ab4a2009-11-20 16:08:53 -0800343{
Nick Pigginb74c79e2011-01-07 17:49:58 +1100344 struct sysfs_dirent *sd;
345
Al Viro10556cb2011-06-20 19:28:19 -0400346 if (mask & MAY_NOT_BLOCK)
Nick Pigginb74c79e2011-01-07 17:49:58 +1100347 return -ECHILD;
348
349 sd = inode->i_private;
Eric W. Biedermane61ab4a2009-11-20 16:08:53 -0800350
351 mutex_lock(&sysfs_mutex);
352 sysfs_refresh_inode(sd, inode);
353 mutex_unlock(&sysfs_mutex);
354
Al Viro2830ba72011-06-20 19:16:29 -0400355 return generic_permission(inode, mask);
Eric W. Biedermane61ab4a2009-11-20 16:08:53 -0800356}