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> 23 #include <linux/magic.h> 24 25 static struct vfsmount *mount; 26 static int mount_count; 27 28 static int fill_super(struct super_block *sb, void *data, int silent) 29 { 30 static struct tree_descr files[] = {{""}}; 31 32 return simple_fill_super(sb, SECURITYFS_MAGIC, files); 33 } 34 35 static struct dentry *get_sb(struct file_system_type *fs_type, 36 int flags, const char *dev_name, 37 void *data) 38 { 39 return mount_single(fs_type, flags, data, fill_super); 40 } 41 42 static struct file_system_type fs_type = { 43 .owner = THIS_MODULE, 44 .name = "securityfs", 45 .mount = get_sb, 46 .kill_sb = kill_litter_super, 47 }; 48 49 /** 50 * securityfs_create_file - create a file in the securityfs filesystem 51 * 52 * @name: a pointer to a string containing the name of the file to create. 53 * @mode: the permission that the file should have 54 * @parent: a pointer to the parent dentry for this file. This should be a 55 * directory dentry if set. If this parameter is %NULL, then the 56 * file will be created in the root of the securityfs filesystem. 57 * @data: a pointer to something that the caller will want to get to later 58 * on. The inode.i_private pointer will point to this value on 59 * the open() call. 60 * @fops: a pointer to a struct file_operations that should be used for 61 * this file. 62 * 63 * This is the basic "create a file" function for securityfs. It allows for a 64 * wide range of flexibility in creating a file, or a directory (if you 65 * want to create a directory, the securityfs_create_dir() function is 66 * recommended to be used instead). 67 * 68 * This function returns a pointer to a dentry if it succeeds. This 69 * pointer must be passed to the securityfs_remove() function when the file is 70 * to be removed (no automatic cleanup happens if your module is unloaded, 71 * you are responsible here). If an error occurs, the function will return 72 * the error value (via ERR_PTR). 73 * 74 * If securityfs is not enabled in the kernel, the value %-ENODEV is 75 * returned. 76 */ 77 struct dentry *securityfs_create_file(const char *name, umode_t mode, 78 struct dentry *parent, void *data, 79 const struct file_operations *fops) 80 { 81 struct dentry *dentry; 82 int is_dir = S_ISDIR(mode); 83 struct inode *dir, *inode; 84 int error; 85 86 if (!is_dir) { 87 BUG_ON(!fops); 88 mode = (mode & S_IALLUGO) | S_IFREG; 89 } 90 91 pr_debug("securityfs: creating file '%s'\n",name); 92 93 error = simple_pin_fs(&fs_type, &mount, &mount_count); 94 if (error) 95 return ERR_PTR(error); 96 97 if (!parent) 98 parent = mount->mnt_root; 99 100 dir = d_inode(parent); 101 102 mutex_lock(&dir->i_mutex); 103 dentry = lookup_one_len(name, parent, strlen(name)); 104 if (IS_ERR(dentry)) 105 goto out; 106 107 if (d_really_is_positive(dentry)) { 108 error = -EEXIST; 109 goto out1; 110 } 111 112 inode = new_inode(dir->i_sb); 113 if (!inode) { 114 error = -ENOMEM; 115 goto out1; 116 } 117 118 inode->i_ino = get_next_ino(); 119 inode->i_mode = mode; 120 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 121 inode->i_private = data; 122 if (is_dir) { 123 inode->i_op = &simple_dir_inode_operations; 124 inode->i_fop = &simple_dir_operations; 125 inc_nlink(inode); 126 inc_nlink(dir); 127 } else { 128 inode->i_fop = fops; 129 } 130 d_instantiate(dentry, inode); 131 dget(dentry); 132 mutex_unlock(&dir->i_mutex); 133 return dentry; 134 135 out1: 136 dput(dentry); 137 dentry = ERR_PTR(error); 138 out: 139 mutex_unlock(&dir->i_mutex); 140 simple_release_fs(&mount, &mount_count); 141 return dentry; 142 } 143 EXPORT_SYMBOL_GPL(securityfs_create_file); 144 145 /** 146 * securityfs_create_dir - create a directory in the securityfs filesystem 147 * 148 * @name: a pointer to a string containing the name of the directory to 149 * create. 150 * @parent: a pointer to the parent dentry for this file. This should be a 151 * directory dentry if set. If this parameter is %NULL, then the 152 * directory will be created in the root of the securityfs filesystem. 153 * 154 * This function creates a directory in securityfs with the given @name. 155 * 156 * This function returns a pointer to a dentry if it succeeds. This 157 * pointer must be passed to the securityfs_remove() function when the file is 158 * to be removed (no automatic cleanup happens if your module is unloaded, 159 * you are responsible here). If an error occurs, %NULL will be returned. 160 * 161 * If securityfs is not enabled in the kernel, the value %-ENODEV is 162 * returned. It is not wise to check for this value, but rather, check for 163 * %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling 164 * code. 165 */ 166 struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) 167 { 168 return securityfs_create_file(name, 169 S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, 170 parent, NULL, NULL); 171 } 172 EXPORT_SYMBOL_GPL(securityfs_create_dir); 173 174 /** 175 * securityfs_remove - removes a file or directory from the securityfs filesystem 176 * 177 * @dentry: a pointer to a the dentry of the file or directory to be removed. 178 * 179 * This function removes a file or directory in securityfs that was previously 180 * created with a call to another securityfs function (like 181 * securityfs_create_file() or variants thereof.) 182 * 183 * This function is required to be called in order for the file to be 184 * removed. No automatic cleanup of files will happen when a module is 185 * removed; you are responsible here. 186 */ 187 void securityfs_remove(struct dentry *dentry) 188 { 189 struct dentry *parent; 190 191 if (!dentry || IS_ERR(dentry)) 192 return; 193 194 parent = dentry->d_parent; 195 if (!parent || d_really_is_negative(parent)) 196 return; 197 198 mutex_lock(&d_inode(parent)->i_mutex); 199 if (simple_positive(dentry)) { 200 if (d_is_dir(dentry)) 201 simple_rmdir(d_inode(parent), dentry); 202 else 203 simple_unlink(d_inode(parent), dentry); 204 dput(dentry); 205 } 206 mutex_unlock(&d_inode(parent)->i_mutex); 207 simple_release_fs(&mount, &mount_count); 208 } 209 EXPORT_SYMBOL_GPL(securityfs_remove); 210 211 static int __init securityfs_init(void) 212 { 213 int retval; 214 215 retval = sysfs_create_mount_point(kernel_kobj, "security"); 216 if (retval) 217 return retval; 218 219 retval = register_filesystem(&fs_type); 220 if (retval) 221 sysfs_remove_mount_point(kernel_kobj, "security"); 222 return retval; 223 } 224 225 core_initcall(securityfs_init); 226 MODULE_LICENSE("GPL"); 227 228