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b67dbf9d »
2005-07-07 [PATCH] add securityfs for all LSMs to use
1 /*
2 * inode.c - securityfs
3 *
4 * Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License version
8 * 2 as published by the Free Software Foundation.
9 *
10 * Based on fs/debugfs/inode.c which had the following copyright notice:
11 * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com>
12 * Copyright (C) 2004 IBM Inc.
13 */
14
15 /* #define DEBUG */
16 #include <linux/module.h>
17 #include <linux/fs.h>
18 #include <linux/mount.h>
19 #include <linux/pagemap.h>
20 #include <linux/init.h>
21 #include <linux/namei.h>
22 #include <linux/security.h>
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2008-10-07 integrity: special fs magic
23 #include <linux/magic.h>
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24
25 static struct vfsmount *mount;
26 static int mount_count;
27
28 static inline int positive(struct dentry *dentry)
29 {
30 return dentry->d_inode && !d_unhashed(dentry);
31 }
32
33 static int fill_super(struct super_block *sb, void *data, int silent)
34 {
35 static struct tree_descr files[] = {{""}};
36
37 return simple_fill_super(sb, SECURITYFS_MAGIC, files);
38 }
39
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40 static struct dentry *get_sb(struct file_system_type *fs_type,
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41 int flags, const char *dev_name,
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42 void *data)
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43 {
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44 return mount_single(fs_type, flags, data, fill_super);
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45 }
46
47 static struct file_system_type fs_type = {
48 .owner = THIS_MODULE,
49 .name = "securityfs",
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50 .mount = get_sb,
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51 .kill_sb = kill_litter_super,
52 };
53
54 /**
55 * securityfs_create_file - create a file in the securityfs filesystem
56 *
57 * @name: a pointer to a string containing the name of the file to create.
58 * @mode: the permission that the file should have
59 * @parent: a pointer to the parent dentry for this file. This should be a
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60 * directory dentry if set. If this parameter is %NULL, then the
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61 * file will be created in the root of the securityfs filesystem.
62 * @data: a pointer to something that the caller will want to get to later
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63 * on. The inode.i_private pointer will point to this value on
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64 * the open() call.
65 * @fops: a pointer to a struct file_operations that should be used for
66 * this file.
67 *
68 * This is the basic "create a file" function for securityfs. It allows for a
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69 * wide range of flexibility in creating a file, or a directory (if you
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70 * want to create a directory, the securityfs_create_dir() function is
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71 * recommended to be used instead).
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72 *
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73 * This function returns a pointer to a dentry if it succeeds. This
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74 * pointer must be passed to the securityfs_remove() function when the file is
75 * to be removed (no automatic cleanup happens if your module is unloaded,
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2009-02-02 securityfs: fix long-broken securityfs_create_file comment
76 * you are responsible here). If an error occurs, the function will return
77 * the erorr value (via ERR_PTR).
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78 *
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79 * If securityfs is not enabled in the kernel, the value %-ENODEV is
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80 * returned.
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81 */
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82 struct dentry *securityfs_create_file(const char *name, umode_t mode,
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83 struct dentry *parent, void *data,
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84 const struct file_operations *fops)
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85 {
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86 struct dentry *dentry;
87 int is_dir = S_ISDIR(mode);
88 struct inode *dir, *inode;
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89 int error;
90
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91 if (!is_dir) {
92 BUG_ON(!fops);
93 mode = (mode & S_IALLUGO) | S_IFREG;
94 }
95
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96 pr_debug("securityfs: creating file '%s'\n",name);
97
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98 error = simple_pin_fs(&fs_type, &mount, &mount_count);
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99 if (error)
100 return ERR_PTR(error);
101
102 if (!parent)
103 parent = mount->mnt_root;
104
105 dir = parent->d_inode;
106
107 mutex_lock(&dir->i_mutex);
108 dentry = lookup_one_len(name, parent, strlen(name));
109 if (IS_ERR(dentry))
110 goto out;
111
112 if (dentry->d_inode) {
113 error = -EEXIST;
114 goto out1;
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115 }
116
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117 inode = new_inode(dir->i_sb);
118 if (!inode) {
119 error = -ENOMEM;
120 goto out1;
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121 }
122
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123 inode->i_ino = get_next_ino();
124 inode->i_mode = mode;
125 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME;
126 inode->i_private = data;
127 if (is_dir) {
128 inode->i_op = &simple_dir_inode_operations;
129 inode->i_fop = &simple_dir_operations;
130 inc_nlink(inode);
131 inc_nlink(dir);
132 } else {
133 inode->i_fop = fops;
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134 }
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135 d_instantiate(dentry, inode);
136 dget(dentry);
137 mutex_unlock(&dir->i_mutex);
138 return dentry;
139
140 out1:
141 dput(dentry);
142 dentry = ERR_PTR(error);
143 out:
144 mutex_unlock(&dir->i_mutex);
145 simple_release_fs(&mount, &mount_count);
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146 return dentry;
147 }
148 EXPORT_SYMBOL_GPL(securityfs_create_file);
149
150 /**
151 * securityfs_create_dir - create a directory in the securityfs filesystem
152 *
153 * @name: a pointer to a string containing the name of the directory to
154 * create.
155 * @parent: a pointer to the parent dentry for this file. This should be a
3f23d815 »
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156 * directory dentry if set. If this parameter is %NULL, then the
b67dbf9d »
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157 * directory will be created in the root of the securityfs filesystem.
158 *
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159 * This function creates a directory in securityfs with the given @name.
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160 *
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161 * This function returns a pointer to a dentry if it succeeds. This
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2005-07-07 [PATCH] add securityfs for all LSMs to use
162 * pointer must be passed to the securityfs_remove() function when the file is
163 * to be removed (no automatic cleanup happens if your module is unloaded,
3f23d815 »
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164 * you are responsible here). If an error occurs, %NULL will be returned.
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165 *
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166 * If securityfs is not enabled in the kernel, the value %-ENODEV is
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167 * returned. It is not wise to check for this value, but rather, check for
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168 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling
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169 * code.
170 */
171 struct dentry *securityfs_create_dir(const char *name, struct dentry *parent)
172 {
173 return securityfs_create_file(name,
174 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO,
175 parent, NULL, NULL);
176 }
177 EXPORT_SYMBOL_GPL(securityfs_create_dir);
178
179 /**
180 * securityfs_remove - removes a file or directory from the securityfs filesystem
181 *
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182 * @dentry: a pointer to a the dentry of the file or directory to be removed.
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183 *
184 * This function removes a file or directory in securityfs that was previously
185 * created with a call to another securityfs function (like
186 * securityfs_create_file() or variants thereof.)
187 *
188 * This function is required to be called in order for the file to be
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189 * removed. No automatic cleanup of files will happen when a module is
190 * removed; you are responsible here.
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191 */
192 void securityfs_remove(struct dentry *dentry)
193 {
194 struct dentry *parent;
195
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196 if (!dentry || IS_ERR(dentry))
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197 return;
198
199 parent = dentry->d_parent;
200 if (!parent || !parent->d_inode)
201 return;
202
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203 mutex_lock(&parent->d_inode->i_mutex);
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204 if (positive(dentry)) {
205 if (dentry->d_inode) {
206 if (S_ISDIR(dentry->d_inode->i_mode))
207 simple_rmdir(parent->d_inode, dentry);
208 else
209 simple_unlink(parent->d_inode, dentry);
210 dput(dentry);
211 }
212 }
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213 mutex_unlock(&parent->d_inode->i_mutex);
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214 simple_release_fs(&mount, &mount_count);
215 }
216 EXPORT_SYMBOL_GPL(securityfs_remove);
217
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218 static struct kobject *security_kobj;
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219
220 static int __init securityfs_init(void)
221 {
222 int retval;
223
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224 security_kobj = kobject_create_and_add("security", kernel_kobj);
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225 if (!security_kobj)
226 return -EINVAL;
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227
228 retval = register_filesystem(&fs_type);
229 if (retval)
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2007-12-20 Kobject: convert remaining kobject_unregister() to kobject_put()
230 kobject_put(security_kobj);
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231 return retval;
232 }
233
234 core_initcall(securityfs_init);
235 MODULE_LICENSE("GPL");
236
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