1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* -*- mode: c; c-basic-offset: 8; -*-
3 * vim: noexpandtab sw=8 ts=8 sts=0:
4 *
5 * inode.c - basic inode and dentry operations.
6 *
7 * Based on sysfs:
8 * sysfs is Copyright (C) 2001, 2002, 2003 Patrick Mochel
9 *
10 * configfs Copyright (C) 2005 Oracle. All rights reserved.
11 *
12 * Please see Documentation/filesystems/configfs/configfs.txt for more
13 * information.
14 */
15
16 #undef DEBUG
17
18 #include <linux/pagemap.h>
19 #include <linux/namei.h>
20 #include <linux/backing-dev.h>
21 #include <linux/capability.h>
22 #include <linux/sched.h>
23 #include <linux/lockdep.h>
24 #include <linux/slab.h>
25
26 #include <linux/configfs.h>
27 #include "configfs_internal.h"
28
29 #ifdef CONFIG_LOCKDEP
30 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
31 #endif
32
33 static const struct address_space_operations configfs_aops = {
34 .readpage = simple_readpage,
35 .write_begin = simple_write_begin,
36 .write_end = simple_write_end,
37 };
38
39 static const struct inode_operations configfs_inode_operations ={
40 .setattr = configfs_setattr,
41 };
42
configfs_setattr(struct dentry * dentry,struct iattr * iattr)43 int configfs_setattr(struct dentry * dentry, struct iattr * iattr)
44 {
45 struct inode * inode = d_inode(dentry);
46 struct configfs_dirent * sd = dentry->d_fsdata;
47 struct iattr * sd_iattr;
48 unsigned int ia_valid = iattr->ia_valid;
49 int error;
50
51 if (!sd)
52 return -EINVAL;
53
54 sd_iattr = sd->s_iattr;
55 if (!sd_iattr) {
56 /* setting attributes for the first time, allocate now */
57 sd_iattr = kzalloc(sizeof(struct iattr), GFP_KERNEL);
58 if (!sd_iattr)
59 return -ENOMEM;
60 /* assign default attributes */
61 sd_iattr->ia_mode = sd->s_mode;
62 sd_iattr->ia_uid = GLOBAL_ROOT_UID;
63 sd_iattr->ia_gid = GLOBAL_ROOT_GID;
64 sd_iattr->ia_atime = sd_iattr->ia_mtime =
65 sd_iattr->ia_ctime = current_time(inode);
66 sd->s_iattr = sd_iattr;
67 }
68 /* attributes were changed atleast once in past */
69
70 error = simple_setattr(dentry, iattr);
71 if (error)
72 return error;
73
74 if (ia_valid & ATTR_UID)
75 sd_iattr->ia_uid = iattr->ia_uid;
76 if (ia_valid & ATTR_GID)
77 sd_iattr->ia_gid = iattr->ia_gid;
78 if (ia_valid & ATTR_ATIME)
79 sd_iattr->ia_atime = timestamp_truncate(iattr->ia_atime,
80 inode);
81 if (ia_valid & ATTR_MTIME)
82 sd_iattr->ia_mtime = timestamp_truncate(iattr->ia_mtime,
83 inode);
84 if (ia_valid & ATTR_CTIME)
85 sd_iattr->ia_ctime = timestamp_truncate(iattr->ia_ctime,
86 inode);
87 if (ia_valid & ATTR_MODE) {
88 umode_t mode = iattr->ia_mode;
89
90 if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
91 mode &= ~S_ISGID;
92 sd_iattr->ia_mode = sd->s_mode = mode;
93 }
94
95 return error;
96 }
97
set_default_inode_attr(struct inode * inode,umode_t mode)98 static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
99 {
100 inode->i_mode = mode;
101 inode->i_atime = inode->i_mtime =
102 inode->i_ctime = current_time(inode);
103 }
104
set_inode_attr(struct inode * inode,struct iattr * iattr)105 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
106 {
107 inode->i_mode = iattr->ia_mode;
108 inode->i_uid = iattr->ia_uid;
109 inode->i_gid = iattr->ia_gid;
110 inode->i_atime = iattr->ia_atime;
111 inode->i_mtime = iattr->ia_mtime;
112 inode->i_ctime = iattr->ia_ctime;
113 }
114
configfs_new_inode(umode_t mode,struct configfs_dirent * sd,struct super_block * s)115 struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
116 struct super_block *s)
117 {
118 struct inode * inode = new_inode(s);
119 if (inode) {
120 inode->i_ino = get_next_ino();
121 inode->i_mapping->a_ops = &configfs_aops;
122 inode->i_op = &configfs_inode_operations;
123
124 if (sd->s_iattr) {
125 /* sysfs_dirent has non-default attributes
126 * get them for the new inode from persistent copy
127 * in sysfs_dirent
128 */
129 set_inode_attr(inode, sd->s_iattr);
130 } else
131 set_default_inode_attr(inode, mode);
132 }
133 return inode;
134 }
135
136 #ifdef CONFIG_LOCKDEP
137
configfs_set_inode_lock_class(struct configfs_dirent * sd,struct inode * inode)138 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
139 struct inode *inode)
140 {
141 int depth = sd->s_depth;
142
143 if (depth > 0) {
144 if (depth <= ARRAY_SIZE(default_group_class)) {
145 lockdep_set_class(&inode->i_rwsem,
146 &default_group_class[depth - 1]);
147 } else {
148 /*
149 * In practice the maximum level of locking depth is
150 * already reached. Just inform about possible reasons.
151 */
152 pr_info("Too many levels of inodes for the locking correctness validator.\n");
153 pr_info("Spurious warnings may appear.\n");
154 }
155 }
156 }
157
158 #else /* CONFIG_LOCKDEP */
159
configfs_set_inode_lock_class(struct configfs_dirent * sd,struct inode * inode)160 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
161 struct inode *inode)
162 {
163 }
164
165 #endif /* CONFIG_LOCKDEP */
166
configfs_create(struct dentry * dentry,umode_t mode)167 struct inode *configfs_create(struct dentry *dentry, umode_t mode)
168 {
169 struct inode *inode = NULL;
170 struct configfs_dirent *sd;
171 struct inode *p_inode;
172
173 if (!dentry)
174 return ERR_PTR(-ENOENT);
175
176 if (d_really_is_positive(dentry))
177 return ERR_PTR(-EEXIST);
178
179 sd = dentry->d_fsdata;
180 inode = configfs_new_inode(mode, sd, dentry->d_sb);
181 if (!inode)
182 return ERR_PTR(-ENOMEM);
183
184 p_inode = d_inode(dentry->d_parent);
185 p_inode->i_mtime = p_inode->i_ctime = current_time(p_inode);
186 configfs_set_inode_lock_class(sd, inode);
187 return inode;
188 }
189
190 /*
191 * Get the name for corresponding element represented by the given configfs_dirent
192 */
configfs_get_name(struct configfs_dirent * sd)193 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
194 {
195 struct configfs_attribute *attr;
196
197 BUG_ON(!sd || !sd->s_element);
198
199 /* These always have a dentry, so use that */
200 if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
201 return sd->s_dentry->d_name.name;
202
203 if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
204 attr = sd->s_element;
205 return attr->ca_name;
206 }
207 return NULL;
208 }
209
210
211 /*
212 * Unhashes the dentry corresponding to given configfs_dirent
213 * Called with parent inode's i_mutex held.
214 */
configfs_drop_dentry(struct configfs_dirent * sd,struct dentry * parent)215 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
216 {
217 struct dentry * dentry = sd->s_dentry;
218
219 if (dentry) {
220 spin_lock(&dentry->d_lock);
221 if (simple_positive(dentry)) {
222 dget_dlock(dentry);
223 __d_drop(dentry);
224 spin_unlock(&dentry->d_lock);
225 simple_unlink(d_inode(parent), dentry);
226 } else
227 spin_unlock(&dentry->d_lock);
228 }
229 }
230
configfs_hash_and_remove(struct dentry * dir,const char * name)231 void configfs_hash_and_remove(struct dentry * dir, const char * name)
232 {
233 struct configfs_dirent * sd;
234 struct configfs_dirent * parent_sd = dir->d_fsdata;
235
236 if (d_really_is_negative(dir))
237 /* no inode means this hasn't been made visible yet */
238 return;
239
240 inode_lock(d_inode(dir));
241 list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
242 if (!sd->s_element)
243 continue;
244 if (!strcmp(configfs_get_name(sd), name)) {
245 spin_lock(&configfs_dirent_lock);
246 list_del_init(&sd->s_sibling);
247 spin_unlock(&configfs_dirent_lock);
248 configfs_drop_dentry(sd, dir);
249 configfs_put(sd);
250 break;
251 }
252 }
253 inode_unlock(d_inode(dir));
254 }
255