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security/inode.c
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/* * inode.c - securityfs * * Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License version * 2 as published by the Free Software Foundation. * * Based on fs/debugfs/inode.c which had the following copyright notice: * Copyright (C) 2004 Greg Kroah-Hartman <greg@kroah.com> * Copyright (C) 2004 IBM Inc. */ /* #define DEBUG */ |
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#include <linux/module.h> #include <linux/fs.h> #include <linux/mount.h> #include <linux/pagemap.h> #include <linux/init.h> #include <linux/namei.h> #include <linux/security.h> |
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#include <linux/magic.h> |
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static struct vfsmount *mount; static int mount_count; /* * TODO: * I think I can get rid of these default_file_ops, but not quite sure... */ static ssize_t default_read_file(struct file *file, char __user *buf, size_t count, loff_t *ppos) { return 0; } static ssize_t default_write_file(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { return count; } static int default_open(struct inode *inode, struct file *file) { |
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if (inode->i_private) file->private_data = inode->i_private; |
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return 0; } |
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static const struct file_operations default_file_ops = { |
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.read = default_read_file, .write = default_write_file, .open = default_open, |
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.llseek = noop_llseek, |
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}; static struct inode *get_inode(struct super_block *sb, int mode, dev_t dev) { struct inode *inode = new_inode(sb); if (inode) { |
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inode->i_ino = get_next_ino(); |
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inode->i_mode = mode; |
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inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; switch (mode & S_IFMT) { default: init_special_inode(inode, mode, dev); break; case S_IFREG: inode->i_fop = &default_file_ops; break; case S_IFDIR: inode->i_op = &simple_dir_inode_operations; inode->i_fop = &simple_dir_operations; /* directory inodes start off with i_nlink == 2 (for "." entry) */ |
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inc_nlink(inode); |
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break; } } return inode; } /* SMP-safe */ static int mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) { struct inode *inode; |
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int error = -ENOMEM; |
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if (dentry->d_inode) return -EEXIST; inode = get_inode(dir->i_sb, mode, dev); if (inode) { d_instantiate(dentry, inode); dget(dentry); error = 0; } return error; } static int mkdir(struct inode *dir, struct dentry *dentry, int mode) { int res; mode = (mode & (S_IRWXUGO | S_ISVTX)) | S_IFDIR; res = mknod(dir, dentry, mode, 0); if (!res) |
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inc_nlink(dir); |
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return res; } static int create(struct inode *dir, struct dentry *dentry, int mode) { mode = (mode & S_IALLUGO) | S_IFREG; return mknod(dir, dentry, mode, 0); } static inline int positive(struct dentry *dentry) { return dentry->d_inode && !d_unhashed(dentry); } static int fill_super(struct super_block *sb, void *data, int silent) { static struct tree_descr files[] = {{""}}; return simple_fill_super(sb, SECURITYFS_MAGIC, files); } |
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static struct dentry *get_sb(struct file_system_type *fs_type, |
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int flags, const char *dev_name, |
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void *data) |
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{ |
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return mount_single(fs_type, flags, data, fill_super); |
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} static struct file_system_type fs_type = { .owner = THIS_MODULE, .name = "securityfs", |
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.mount = get_sb, |
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.kill_sb = kill_litter_super, }; static int create_by_name(const char *name, mode_t mode, struct dentry *parent, struct dentry **dentry) { int error = 0; *dentry = NULL; /* If the parent is not specified, we create it in the root. * We need the root dentry to do this, which is in the super * block. A pointer to that is in the struct vfsmount that we * have around. */ |
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if (!parent) parent = mount->mnt_sb->s_root; |
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|
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mutex_lock(&parent->d_inode->i_mutex); |
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*dentry = lookup_one_len(name, parent, strlen(name)); |
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if (!IS_ERR(*dentry)) { |
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if ((mode & S_IFMT) == S_IFDIR) error = mkdir(parent->d_inode, *dentry, mode); else error = create(parent->d_inode, *dentry, mode); |
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if (error) dput(*dentry); |
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} else |
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error = PTR_ERR(*dentry); |
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mutex_unlock(&parent->d_inode->i_mutex); |
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return error; } /** * securityfs_create_file - create a file in the securityfs filesystem * * @name: a pointer to a string containing the name of the file to create. * @mode: the permission that the file should have * @parent: a pointer to the parent dentry for this file. This should be a |
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* directory dentry if set. If this parameter is %NULL, then the |
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* file will be created in the root of the securityfs filesystem. * @data: a pointer to something that the caller will want to get to later |
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* on. The inode.i_private pointer will point to this value on |
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* the open() call. * @fops: a pointer to a struct file_operations that should be used for * this file. * * This is the basic "create a file" function for securityfs. It allows for a |
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* wide range of flexibility in creating a file, or a directory (if you |
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* want to create a directory, the securityfs_create_dir() function is |
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* recommended to be used instead). |
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* |
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* This function returns a pointer to a dentry if it succeeds. This |
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* pointer must be passed to the securityfs_remove() function when the file is * to be removed (no automatic cleanup happens if your module is unloaded, |
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* you are responsible here). If an error occurs, the function will return * the erorr value (via ERR_PTR). |
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* |
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* If securityfs is not enabled in the kernel, the value %-ENODEV is |
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* returned. |
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*/ struct dentry *securityfs_create_file(const char *name, mode_t mode, struct dentry *parent, void *data, |
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const struct file_operations *fops) |
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{ struct dentry *dentry = NULL; int error; pr_debug("securityfs: creating file '%s' ",name); |
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error = simple_pin_fs(&fs_type, &mount, &mount_count); |
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if (error) { dentry = ERR_PTR(error); goto exit; } error = create_by_name(name, mode, parent, &dentry); if (error) { dentry = ERR_PTR(error); simple_release_fs(&mount, &mount_count); goto exit; } if (dentry->d_inode) { if (fops) dentry->d_inode->i_fop = fops; if (data) |
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dentry->d_inode->i_private = data; |
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} exit: return dentry; } EXPORT_SYMBOL_GPL(securityfs_create_file); /** * securityfs_create_dir - create a directory in the securityfs filesystem * * @name: a pointer to a string containing the name of the directory to * create. * @parent: a pointer to the parent dentry for this file. This should be a |
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* directory dentry if set. If this parameter is %NULL, then the |
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* directory will be created in the root of the securityfs filesystem. * |
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* This function creates a directory in securityfs with the given @name. |
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* |
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* This function returns a pointer to a dentry if it succeeds. This |
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* pointer must be passed to the securityfs_remove() function when the file is * to be removed (no automatic cleanup happens if your module is unloaded, |
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* you are responsible here). If an error occurs, %NULL will be returned. |
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* |
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* If securityfs is not enabled in the kernel, the value %-ENODEV is |
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* returned. It is not wise to check for this value, but rather, check for |
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* %NULL or !%NULL instead as to eliminate the need for #ifdef in the calling |
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* code. */ struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) { return securityfs_create_file(name, S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO, parent, NULL, NULL); } EXPORT_SYMBOL_GPL(securityfs_create_dir); /** * securityfs_remove - removes a file or directory from the securityfs filesystem * |
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* @dentry: a pointer to a the dentry of the file or directory to be removed. |
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* * This function removes a file or directory in securityfs that was previously * created with a call to another securityfs function (like * securityfs_create_file() or variants thereof.) * * This function is required to be called in order for the file to be |
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* removed. No automatic cleanup of files will happen when a module is * removed; you are responsible here. |
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*/ void securityfs_remove(struct dentry *dentry) { struct dentry *parent; |
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if (!dentry || IS_ERR(dentry)) |
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return; parent = dentry->d_parent; if (!parent || !parent->d_inode) return; |
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mutex_lock(&parent->d_inode->i_mutex); |
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if (positive(dentry)) { if (dentry->d_inode) { if (S_ISDIR(dentry->d_inode->i_mode)) simple_rmdir(parent->d_inode, dentry); else simple_unlink(parent->d_inode, dentry); dput(dentry); } } |
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mutex_unlock(&parent->d_inode->i_mutex); |
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simple_release_fs(&mount, &mount_count); } EXPORT_SYMBOL_GPL(securityfs_remove); |
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static struct kobject *security_kobj; |
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static int __init securityfs_init(void) { int retval; |
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security_kobj = kobject_create_and_add("security", kernel_kobj); |
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if (!security_kobj) return -EINVAL; |
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retval = register_filesystem(&fs_type); if (retval) |
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kobject_put(security_kobj); |
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return retval; } |
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core_initcall(securityfs_init); |
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MODULE_LICENSE("GPL"); |