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350 lines
11 KiB
350 lines
11 KiB
// SPDX-License-Identifier: GPL-2.0-only |
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/* |
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* inode.c - securityfs |
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* |
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* Copyright (C) 2005 Greg Kroah-Hartman <[email protected]> |
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* |
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* Based on fs/debugfs/inode.c which had the following copyright notice: |
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* Copyright (C) 2004 Greg Kroah-Hartman <[email protected]> |
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* Copyright (C) 2004 IBM Inc. |
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*/ |
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/* #define DEBUG */ |
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#include <linux/sysfs.h> |
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#include <linux/kobject.h> |
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#include <linux/fs.h> |
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#include <linux/fs_context.h> |
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#include <linux/mount.h> |
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#include <linux/pagemap.h> |
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#include <linux/init.h> |
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#include <linux/namei.h> |
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#include <linux/security.h> |
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#include <linux/lsm_hooks.h> |
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#include <linux/magic.h> |
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static struct vfsmount *mount; |
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static int mount_count; |
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static void securityfs_free_inode(struct inode *inode) |
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{ |
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if (S_ISLNK(inode->i_mode)) |
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kfree(inode->i_link); |
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free_inode_nonrcu(inode); |
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} |
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static const struct super_operations securityfs_super_operations = { |
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.statfs = simple_statfs, |
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.free_inode = securityfs_free_inode, |
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}; |
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static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc) |
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{ |
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static const struct tree_descr files[] = {{""}}; |
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int error; |
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error = simple_fill_super(sb, SECURITYFS_MAGIC, files); |
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if (error) |
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return error; |
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sb->s_op = &securityfs_super_operations; |
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return 0; |
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} |
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static int securityfs_get_tree(struct fs_context *fc) |
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{ |
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return get_tree_single(fc, securityfs_fill_super); |
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} |
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static const struct fs_context_operations securityfs_context_ops = { |
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.get_tree = securityfs_get_tree, |
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}; |
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static int securityfs_init_fs_context(struct fs_context *fc) |
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{ |
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fc->ops = &securityfs_context_ops; |
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return 0; |
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} |
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static struct file_system_type fs_type = { |
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.owner = THIS_MODULE, |
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.name = "securityfs", |
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.init_fs_context = securityfs_init_fs_context, |
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.kill_sb = kill_litter_super, |
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}; |
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/** |
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* securityfs_create_dentry - create a dentry in the securityfs filesystem |
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* |
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* @name: a pointer to a string containing the name of the file to create. |
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* @mode: the permission that the file should have |
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* @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. |
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* @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. |
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* @fops: a pointer to a struct file_operations that should be used for |
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* this file. |
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* @iops: a point to a struct of inode_operations that should be used for |
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* this file/dir |
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* |
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* This is the basic "create a file/dir/symlink" function for |
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* securityfs. It allows for a wide range of flexibility in creating |
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* a file, or a directory (if you want to create a directory, the |
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* securityfs_create_dir() function is recommended to be used |
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* 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 |
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* file is to be removed (no automatic cleanup happens if your module |
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* is unloaded, you are responsible here). If an error occurs, the |
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* function will return the error 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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*/ |
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static struct dentry *securityfs_create_dentry(const char *name, umode_t mode, |
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struct dentry *parent, void *data, |
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const struct file_operations *fops, |
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const struct inode_operations *iops) |
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{ |
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struct dentry *dentry; |
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struct inode *dir, *inode; |
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int error; |
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if (!(mode & S_IFMT)) |
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mode = (mode & S_IALLUGO) | S_IFREG; |
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pr_debug("securityfs: creating file '%s'\n",name); |
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error = simple_pin_fs(&fs_type, &mount, &mount_count); |
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if (error) |
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return ERR_PTR(error); |
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if (!parent) |
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parent = mount->mnt_root; |
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dir = d_inode(parent); |
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inode_lock(dir); |
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dentry = lookup_one_len(name, parent, strlen(name)); |
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if (IS_ERR(dentry)) |
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goto out; |
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if (d_really_is_positive(dentry)) { |
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error = -EEXIST; |
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goto out1; |
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} |
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inode = new_inode(dir->i_sb); |
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if (!inode) { |
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error = -ENOMEM; |
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goto out1; |
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} |
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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(inode); |
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inode->i_private = data; |
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if (S_ISDIR(mode)) { |
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inode->i_op = &simple_dir_inode_operations; |
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inode->i_fop = &simple_dir_operations; |
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inc_nlink(inode); |
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inc_nlink(dir); |
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} else if (S_ISLNK(mode)) { |
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inode->i_op = iops ? iops : &simple_symlink_inode_operations; |
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inode->i_link = data; |
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} else { |
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inode->i_fop = fops; |
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} |
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d_instantiate(dentry, inode); |
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dget(dentry); |
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inode_unlock(dir); |
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return dentry; |
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out1: |
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dput(dentry); |
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dentry = ERR_PTR(error); |
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out: |
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inode_unlock(dir); |
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simple_release_fs(&mount, &mount_count); |
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return dentry; |
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} |
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/** |
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* securityfs_create_file - create a file in the securityfs filesystem |
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* |
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* @name: a pointer to a string containing the name of the file to create. |
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* @mode: the permission that the file should have |
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* @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. |
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* @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. |
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* @fops: a pointer to a struct file_operations that should be used for |
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* this file. |
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* |
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* This function creates a file 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 |
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* 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 |
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* the error 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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*/ |
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struct dentry *securityfs_create_file(const char *name, umode_t mode, |
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struct dentry *parent, void *data, |
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const struct file_operations *fops) |
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{ |
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return securityfs_create_dentry(name, mode, parent, data, fops, NULL); |
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} |
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EXPORT_SYMBOL_GPL(securityfs_create_file); |
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/** |
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* securityfs_create_dir - create a directory in the securityfs filesystem |
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* |
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* @name: a pointer to a string containing the name of the directory to |
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* create. |
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* @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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* |
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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 |
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* 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 |
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* the error 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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*/ |
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struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) |
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{ |
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return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL); |
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} |
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EXPORT_SYMBOL_GPL(securityfs_create_dir); |
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/** |
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* securityfs_create_symlink - create a symlink in the securityfs filesystem |
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* |
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* @name: a pointer to a string containing the name of the symlink to |
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* create. |
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* @parent: a pointer to the parent dentry for the symlink. 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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* @target: a pointer to a string containing the name of the symlink's target. |
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* If this parameter is %NULL, then the @iops parameter needs to be |
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* setup to handle .readlink and .get_link inode_operations. |
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* @iops: a pointer to the struct inode_operations to use for the symlink. If |
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* this parameter is %NULL, then the default simple_symlink_inode |
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* operations will be used. |
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* |
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* This function creates a symlink 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 |
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* 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 |
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* the error 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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*/ |
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struct dentry *securityfs_create_symlink(const char *name, |
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struct dentry *parent, |
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const char *target, |
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const struct inode_operations *iops) |
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{ |
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struct dentry *dent; |
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char *link = NULL; |
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if (target) { |
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link = kstrdup(target, GFP_KERNEL); |
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if (!link) |
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return ERR_PTR(-ENOMEM); |
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} |
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dent = securityfs_create_dentry(name, S_IFLNK | 0444, parent, |
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link, NULL, iops); |
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if (IS_ERR(dent)) |
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kfree(link); |
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return dent; |
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} |
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EXPORT_SYMBOL_GPL(securityfs_create_symlink); |
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/** |
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* securityfs_remove - removes a file or directory from the securityfs filesystem |
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* |
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* @dentry: a pointer to a the dentry of the file or directory to be removed. |
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* |
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* This function removes a file or directory in securityfs that was previously |
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* created with a call to another securityfs function (like |
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* securityfs_create_file() or variants thereof.) |
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* |
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* 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 |
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* removed; you are responsible here. |
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*/ |
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void securityfs_remove(struct dentry *dentry) |
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{ |
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struct inode *dir; |
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if (!dentry || IS_ERR(dentry)) |
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return; |
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dir = d_inode(dentry->d_parent); |
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inode_lock(dir); |
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if (simple_positive(dentry)) { |
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if (d_is_dir(dentry)) |
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simple_rmdir(dir, dentry); |
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else |
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simple_unlink(dir, dentry); |
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dput(dentry); |
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} |
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inode_unlock(dir); |
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simple_release_fs(&mount, &mount_count); |
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} |
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EXPORT_SYMBOL_GPL(securityfs_remove); |
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#ifdef CONFIG_SECURITY |
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static struct dentry *lsm_dentry; |
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static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count, |
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loff_t *ppos) |
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{ |
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return simple_read_from_buffer(buf, count, ppos, lsm_names, |
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strlen(lsm_names)); |
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} |
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static const struct file_operations lsm_ops = { |
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.read = lsm_read, |
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.llseek = generic_file_llseek, |
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}; |
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#endif |
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static int __init securityfs_init(void) |
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{ |
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int retval; |
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retval = sysfs_create_mount_point(kernel_kobj, "security"); |
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if (retval) |
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return retval; |
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retval = register_filesystem(&fs_type); |
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if (retval) { |
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sysfs_remove_mount_point(kernel_kobj, "security"); |
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return retval; |
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} |
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#ifdef CONFIG_SECURITY |
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lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL, |
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&lsm_ops); |
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#endif |
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return 0; |
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} |
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core_initcall(securityfs_init);
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