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
28 static struct lock_class_key default_group_class[MAX_LOCK_DEPTH];
29 #endif
30 
31 static const struct inode_operations configfs_inode_operations ={
32 	.setattr	= configfs_setattr,
33 };
34 
configfs_setattr(struct user_namespace * mnt_userns,struct dentry * dentry,struct iattr * iattr)35 int configfs_setattr(struct user_namespace *mnt_userns, 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(mnt_userns, 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 
set_default_inode_attr(struct inode * inode,umode_t mode)88 static inline void set_default_inode_attr(struct inode * inode, umode_t mode)
89 {
90 	inode->i_mode = mode;
91 	inode->i_atime = inode->i_mtime =
92 		inode->i_ctime = current_time(inode);
93 }
94 
set_inode_attr(struct inode * inode,struct iattr * iattr)95 static inline void set_inode_attr(struct inode * inode, struct iattr * iattr)
96 {
97 	inode->i_mode = iattr->ia_mode;
98 	inode->i_uid = iattr->ia_uid;
99 	inode->i_gid = iattr->ia_gid;
100 	inode->i_atime = iattr->ia_atime;
101 	inode->i_mtime = iattr->ia_mtime;
102 	inode->i_ctime = iattr->ia_ctime;
103 }
104 
configfs_new_inode(umode_t mode,struct configfs_dirent * sd,struct super_block * s)105 struct inode *configfs_new_inode(umode_t mode, struct configfs_dirent *sd,
106 				 struct super_block *s)
107 {
108 	struct inode * inode = new_inode(s);
109 	if (inode) {
110 		inode->i_ino = get_next_ino();
111 		inode->i_mapping->a_ops = &ram_aops;
112 		inode->i_op = &configfs_inode_operations;
113 
114 		if (sd->s_iattr) {
115 			/* sysfs_dirent has non-default attributes
116 			 * get them for the new inode from persistent copy
117 			 * in sysfs_dirent
118 			 */
119 			set_inode_attr(inode, sd->s_iattr);
120 		} else
121 			set_default_inode_attr(inode, mode);
122 	}
123 	return inode;
124 }
125 
126 #ifdef CONFIG_LOCKDEP
127 
configfs_set_inode_lock_class(struct configfs_dirent * sd,struct inode * inode)128 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
129 					  struct inode *inode)
130 {
131 	int depth = sd->s_depth;
132 
133 	if (depth > 0) {
134 		if (depth <= ARRAY_SIZE(default_group_class)) {
135 			lockdep_set_class(&inode->i_rwsem,
136 					  &default_group_class[depth - 1]);
137 		} else {
138 			/*
139 			 * In practice the maximum level of locking depth is
140 			 * already reached. Just inform about possible reasons.
141 			 */
142 			pr_info("Too many levels of inodes for the locking correctness validator.\n");
143 			pr_info("Spurious warnings may appear.\n");
144 		}
145 	}
146 }
147 
148 #else /* CONFIG_LOCKDEP */
149 
configfs_set_inode_lock_class(struct configfs_dirent * sd,struct inode * inode)150 static void configfs_set_inode_lock_class(struct configfs_dirent *sd,
151 					  struct inode *inode)
152 {
153 }
154 
155 #endif /* CONFIG_LOCKDEP */
156 
configfs_create(struct dentry * dentry,umode_t mode)157 struct inode *configfs_create(struct dentry *dentry, umode_t mode)
158 {
159 	struct inode *inode = NULL;
160 	struct configfs_dirent *sd;
161 	struct inode *p_inode;
162 
163 	if (!dentry)
164 		return ERR_PTR(-ENOENT);
165 
166 	if (d_really_is_positive(dentry))
167 		return ERR_PTR(-EEXIST);
168 
169 	sd = dentry->d_fsdata;
170 	inode = configfs_new_inode(mode, sd, dentry->d_sb);
171 	if (!inode)
172 		return ERR_PTR(-ENOMEM);
173 
174 	p_inode = d_inode(dentry->d_parent);
175 	p_inode->i_mtime = p_inode->i_ctime = current_time(p_inode);
176 	configfs_set_inode_lock_class(sd, inode);
177 	return inode;
178 }
179 
180 /*
181  * Get the name for corresponding element represented by the given configfs_dirent
182  */
configfs_get_name(struct configfs_dirent * sd)183 const unsigned char * configfs_get_name(struct configfs_dirent *sd)
184 {
185 	struct configfs_attribute *attr;
186 
187 	BUG_ON(!sd || !sd->s_element);
188 
189 	/* These always have a dentry, so use that */
190 	if (sd->s_type & (CONFIGFS_DIR | CONFIGFS_ITEM_LINK))
191 		return sd->s_dentry->d_name.name;
192 
193 	if (sd->s_type & (CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)) {
194 		attr = sd->s_element;
195 		return attr->ca_name;
196 	}
197 	return NULL;
198 }
199 
200 
201 /*
202  * Unhashes the dentry corresponding to given configfs_dirent
203  * Called with parent inode's i_mutex held.
204  */
configfs_drop_dentry(struct configfs_dirent * sd,struct dentry * parent)205 void configfs_drop_dentry(struct configfs_dirent * sd, struct dentry * parent)
206 {
207 	struct dentry * dentry = sd->s_dentry;
208 
209 	if (dentry) {
210 		spin_lock(&dentry->d_lock);
211 		if (simple_positive(dentry)) {
212 			dget_dlock(dentry);
213 			__d_drop(dentry);
214 			spin_unlock(&dentry->d_lock);
215 			simple_unlink(d_inode(parent), dentry);
216 		} else
217 			spin_unlock(&dentry->d_lock);
218 	}
219 }
220 
configfs_hash_and_remove(struct dentry * dir,const char * name)221 void configfs_hash_and_remove(struct dentry * dir, const char * name)
222 {
223 	struct configfs_dirent * sd;
224 	struct configfs_dirent * parent_sd = dir->d_fsdata;
225 
226 	if (d_really_is_negative(dir))
227 		/* no inode means this hasn't been made visible yet */
228 		return;
229 
230 	inode_lock(d_inode(dir));
231 	list_for_each_entry(sd, &parent_sd->s_children, s_sibling) {
232 		if (!sd->s_element)
233 			continue;
234 		if (!strcmp(configfs_get_name(sd), name)) {
235 			spin_lock(&configfs_dirent_lock);
236 			list_del_init(&sd->s_sibling);
237 			spin_unlock(&configfs_dirent_lock);
238 			configfs_drop_dentry(sd, dir);
239 			configfs_put(sd);
240 			break;
241 		}
242 	}
243 	inode_unlock(d_inode(dir));
244 }
245