diff options
Diffstat (limited to 'security/inode.c')
| -rw-r--r-- | security/inode.c | 350 |
1 files changed, 350 insertions, 0 deletions
diff --git a/security/inode.c b/security/inode.c new file mode 100644 index 000000000..6c3269397 --- /dev/null +++ b/security/inode.c @@ -0,0 +1,350 @@ +// 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> + +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_litter_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; + + if (!(mode & S_IFMT)) + mode = (mode & S_IALLUGO) | S_IFREG; + + pr_debug("securityfs: creating file '%s'\n",name); + + error = simple_pin_fs(&fs_type, &mount, &mount_count); + if (error) + return ERR_PTR(error); + + if (!parent) + parent = mount->mnt_root; + + dir = d_inode(parent); + + inode_lock(dir); + dentry = lookup_one_len(name, parent, strlen(name)); + if (IS_ERR(dentry)) + goto out; + + if (d_really_is_positive(dentry)) { + error = -EEXIST; + goto out1; + } + + inode = new_inode(dir->i_sb); + if (!inode) { + error = -ENOMEM; + goto out1; + } + + inode->i_ino = get_next_ino(); + inode->i_mode = mode; + inode->i_atime = inode->i_mtime = inode->i_ctime = current_time(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_instantiate(dentry, inode); + dget(dentry); + inode_unlock(dir); + return dentry; + +out1: + dput(dentry); + dentry = ERR_PTR(error); +out: + inode_unlock(dir); + 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); + +/** + * 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. + */ +void securityfs_remove(struct dentry *dentry) +{ + struct inode *dir; + + if (!dentry || IS_ERR(dentry)) + return; + + dir = d_inode(dentry->d_parent); + inode_lock(dir); + if (simple_positive(dentry)) { + if (d_is_dir(dentry)) + simple_rmdir(dir, dentry); + else + simple_unlink(dir, dentry); + dput(dentry); + } + inode_unlock(dir); + simple_release_fs(&mount, &mount_count); +} +EXPORT_SYMBOL_GPL(securityfs_remove); + +#ifdef CONFIG_SECURITY +static struct dentry *lsm_dentry; +static ssize_t lsm_read(struct file *filp, char __user *buf, size_t count, + loff_t *ppos) +{ + return simple_read_from_buffer(buf, count, ppos, lsm_names, + strlen(lsm_names)); +} + +static const struct file_operations lsm_ops = { + .read = lsm_read, + .llseek = generic_file_llseek, +}; +#endif + +static 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; +} +core_initcall(securityfs_init); |