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