// SPDX-License-Identifier: GPL-2.0-only /* * inode.c - securityfs * * Copyright (C) 2005 Greg Kroah-Hartman <gregkh@suse.de> * * 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 */ #include <linux/sysfs.h> #include <linux/kobject.h> #include <linux/fs.h> #include <linux/fs_context.h> #include <linux/mount.h> #include <linux/pagemap.h> #include <linux/init.h> #include <linux/namei.h> #include <linux/security.h> #include <linux/lsm_hooks.h> #include <linux/magic.h> #include "lsm.h" static struct vfsmount *mount; static int mount_count; static void securityfs_free_inode(struct inode *inode) { if (S_ISLNK(inode->i_mode)) kfree(inode->i_link); free_inode_nonrcu(inode); } static const struct super_operations securityfs_super_operations = { .statfs = simple_statfs, .free_inode = securityfs_free_inode, }; static int securityfs_fill_super(struct super_block *sb, struct fs_context *fc) { static const struct tree_descr files[] = {{""}}; int error; error = simple_fill_super(sb, SECURITYFS_MAGIC, files); if (error) return error; sb->s_op = &securityfs_super_operations; return 0; } static int securityfs_get_tree(struct fs_context *fc) { return get_tree_single(fc, securityfs_fill_super); } static const struct fs_context_operations securityfs_context_ops = { .get_tree = securityfs_get_tree, }; static int securityfs_init_fs_context(struct fs_context *fc) { fc->ops = &securityfs_context_ops; return 0; } static struct file_system_type fs_type = { .owner = THIS_MODULE, .name = "securityfs", .init_fs_context = securityfs_init_fs_context, .kill_sb = kill_anon_super, }; /** * securityfs_create_dentry - create a dentry 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 * directory dentry if set. If this parameter is %NULL, then the * 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 * on. The inode.i_private pointer will point to this value on * the open() call. * @fops: a pointer to a struct file_operations that should be used for * this file. * @iops: a point to a struct of inode_operations that should be used for * this file/dir * * This is the basic "create a file/dir/symlink" function for * securityfs. It allows for a wide range of flexibility in creating * a file, or a directory (if you want to create a directory, the * securityfs_create_dir() function is recommended to be used * instead). * * This function returns a pointer to a dentry if it succeeds. This * 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, you are responsible here). If an error occurs, the * function will return the error value (via ERR_PTR). * * If securityfs is not enabled in the kernel, the value %-ENODEV is * returned. */ static struct dentry *securityfs_create_dentry(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops, const struct inode_operations *iops) { struct dentry *dentry; struct inode *dir, *inode; int error; bool pinned = false; if (!(mode & S_IFMT)) mode = (mode & S_IALLUGO) | S_IFREG; pr_debug("securityfs: creating file '%s'\n",name); if (!parent) { error = simple_pin_fs(&fs_type, &mount, &mount_count); if (error) return ERR_PTR(error); pinned = true; parent = mount->mnt_root; } inode = new_inode(parent->d_sb); if (unlikely(!inode)) { dentry = ERR_PTR(-ENOMEM); goto out; } dir = d_inode(parent); dentry = simple_start_creating(parent, name); if (IS_ERR(dentry)) { iput(inode); goto out; } inode->i_ino = get_next_ino(); inode->i_mode = mode; simple_inode_init_ts(inode); inode->i_private = data; if (S_ISDIR(mode)) { inode->i_op = &simple_dir_inode_operations; inode->i_fop = &simple_dir_operations; inc_nlink(inode); inc_nlink(dir); } else if (S_ISLNK(mode)) { inode->i_op = iops ? iops : &simple_symlink_inode_operations; inode->i_link = data; } else { inode->i_fop = fops; } d_make_persistent(dentry, inode); simple_done_creating(dentry); return dentry; // borrowed out: if (pinned) simple_release_fs(&mount, &mount_count); return dentry; } /** * 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 * directory dentry if set. If this parameter is %NULL, then the * 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 * on. The inode.i_private pointer will point to this value on * the open() call. * @fops: a pointer to a struct file_operations that should be used for * this file. * * This function creates a file in securityfs with the given @name. * * This function returns a pointer to a dentry if it succeeds. This * 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, * you are responsible here). If an error occurs, the function will return * the error value (via ERR_PTR). * * If securityfs is not enabled in the kernel, the value %-ENODEV is * returned. */ struct dentry *securityfs_create_file(const char *name, umode_t mode, struct dentry *parent, void *data, const struct file_operations *fops) { return securityfs_create_dentry(name, mode, parent, data, fops, NULL); } 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 * directory dentry if set. If this parameter is %NULL, then the * directory will be created in the root of the securityfs filesystem. * * This function creates a directory in securityfs with the given @name. * * This function returns a pointer to a dentry if it succeeds. This * 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, * you are responsible here). If an error occurs, the function will return * the error value (via ERR_PTR). * * If securityfs is not enabled in the kernel, the value %-ENODEV is * returned. */ struct dentry *securityfs_create_dir(const char *name, struct dentry *parent) { return securityfs_create_file(name, S_IFDIR | 0755, parent, NULL, NULL); } EXPORT_SYMBOL_GPL(securityfs_create_dir); /** * securityfs_create_symlink - create a symlink in the securityfs filesystem * * @name: a pointer to a string containing the name of the symlink to * create. * @parent: a pointer to the parent dentry for the symlink. This should be a * directory dentry if set. If this parameter is %NULL, then the * directory will be created in the root of the securityfs filesystem. * @target: a pointer to a string containing the name of the symlink's target. * If this parameter is %NULL, then the @iops parameter needs to be * setup to handle .readlink and .get_link inode_operations. * @iops: a pointer to the struct inode_operations to use for the symlink. If * this parameter is %NULL, then the default simple_symlink_inode * operations will be used. * * This function creates a symlink in securityfs with the given @name. * * This function returns a pointer to a dentry if it succeeds. This * 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, * you are responsible here). If an error occurs, the function will return * the error value (via ERR_PTR). * * If securityfs is not enabled in the kernel, the value %-ENODEV is * returned. */ struct dentry *securityfs_create_symlink(const char *name, struct dentry *parent, const char *target, const struct inode_operations *iops) { struct dentry *dent; char *link = NULL; if (target) { link = kstrdup(target, GFP_KERNEL); if (!link) return ERR_PTR(-ENOMEM); } dent = securityfs_create_dentry(name, S_IFLNK | 0444, parent, link, NULL, iops); if (IS_ERR(dent)) kfree(link); return dent; } EXPORT_SYMBOL_GPL(securityfs_create_symlink); static void remove_one(struct dentry *victim) { if (victim->d_parent == victim->d_sb->s_root) simple_release_fs(&mount, &mount_count); } /** * securityfs_remove - removes a file or directory from the securityfs filesystem * * @dentry: a pointer to a the dentry of the file or directory to be removed. * * 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 * removed. No automatic cleanup of files will happen when a module is * removed; you are responsible here. * * AV: when applied to directory it will take all children out; no need to call * it for descendents if ancestor is getting killed. */ void securityfs_remove(struct dentry *dentry) { if (IS_ERR_OR_NULL(dentry)) return; simple_pin_fs(&fs_type, &mount, &mount_count); simple_recursive_removal(dentry, remove_one); simple_release_fs(&mount, &mount_count); } EXPORT_SYMBOL_GPL(securityfs_remove); #ifdef CONFIG_SECURITY #include <linux/spinlock.h> static struct dentry *lsm_dentry; static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) { int i; static char *str; static size_t len; static DEFINE_SPINLOCK(lock); /* NOTE: we never free or modify the string once it is set */ if (unlikely(!str || !len)) { char *str_tmp; size_t len_tmp = 0; for (i = 0; i < lsm_active_cnt; i++) /* the '+ 1' accounts for either a comma or a NUL */ len_tmp += strlen(lsm_idlist[i]->name) + 1; str_tmp = kmalloc(len_tmp, GFP_KERNEL); if (!str_tmp) return -ENOMEM; str_tmp[0] = '\0'; for (i = 0; i < lsm_active_cnt; i++) { if (i > 0) strcat(str_tmp, ","); strcat(str_tmp, lsm_idlist[i]->name); } spin_lock(&lock); if (!str) { str = str_tmp; len = len_tmp - 1; } else kfree(str_tmp); spin_unlock(&lock); } return simple_read_from_buffer(buf, count, ppos, str, len); } static const struct file_operations lsm_ops = { .read = lsm_read, .llseek = generic_file_llseek, }; #endif int __init securityfs_init(void) { int retval; retval = sysfs_create_mount_point(kernel_kobj, "security"); if (retval) return retval; retval = register_filesystem(&fs_type); if (retval) { sysfs_remove_mount_point(kernel_kobj, "security"); return retval; } #ifdef CONFIG_SECURITY lsm_dentry = securityfs_create_file("lsm", 0444, NULL, NULL, &lsm_ops); #endif return 0; }
