diff options
Diffstat (limited to 'fs/debugfs/inode.c')
| -rw-r--r-- | fs/debugfs/inode.c | 919 |
1 files changed, 919 insertions, 0 deletions
diff --git a/fs/debugfs/inode.c b/fs/debugfs/inode.c new file mode 100644 index 000000000..08ef68516 --- /dev/null +++ b/fs/debugfs/inode.c @@ -0,0 +1,919 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * inode.c - part of debugfs, a tiny little debug file system + * + * Copyright (C) 2004,2019 Greg Kroah-Hartman <greg@kroah.com> + * Copyright (C) 2004 IBM Inc. + * Copyright (C) 2019 Linux Foundation <gregkh@linuxfoundation.org> + * + * debugfs is for people to use instead of /proc or /sys. + * See ./Documentation/core-api/kernel-api.rst for more details. + */ + +#define pr_fmt(fmt) "debugfs: " fmt + +#include <linux/module.h> +#include <linux/fs.h> +#include <linux/mount.h> +#include <linux/pagemap.h> +#include <linux/init.h> +#include <linux/kobject.h> +#include <linux/namei.h> +#include <linux/debugfs.h> +#include <linux/fsnotify.h> +#include <linux/string.h> +#include <linux/seq_file.h> +#include <linux/parser.h> +#include <linux/magic.h> +#include <linux/slab.h> +#include <linux/security.h> + +#include "internal.h" + +#define DEBUGFS_DEFAULT_MODE 0700 + +static struct vfsmount *debugfs_mount; +static int debugfs_mount_count; +static bool debugfs_registered; +static unsigned int debugfs_allow __ro_after_init = DEFAULT_DEBUGFS_ALLOW_BITS; + +/* + * Don't allow access attributes to be changed whilst the kernel is locked down + * so that we can use the file mode as part of a heuristic to determine whether + * to lock down individual files. + */ +static int debugfs_setattr(struct user_namespace *mnt_userns, + struct dentry *dentry, struct iattr *ia) +{ + int ret; + + if (ia->ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID)) { + ret = security_locked_down(LOCKDOWN_DEBUGFS); + if (ret) + return ret; + } + return simple_setattr(&init_user_ns, dentry, ia); +} + +static const struct inode_operations debugfs_file_inode_operations = { + .setattr = debugfs_setattr, +}; +static const struct inode_operations debugfs_dir_inode_operations = { + .lookup = simple_lookup, + .setattr = debugfs_setattr, +}; +static const struct inode_operations debugfs_symlink_inode_operations = { + .get_link = simple_get_link, + .setattr = debugfs_setattr, +}; + +static struct inode *debugfs_get_inode(struct super_block *sb) +{ + struct inode *inode = new_inode(sb); + if (inode) { + inode->i_ino = get_next_ino(); + inode->i_atime = inode->i_mtime = + inode->i_ctime = current_time(inode); + } + return inode; +} + +struct debugfs_mount_opts { + kuid_t uid; + kgid_t gid; + umode_t mode; + /* Opt_* bitfield. */ + unsigned int opts; +}; + +enum { + Opt_uid, + Opt_gid, + Opt_mode, + Opt_err +}; + +static const match_table_t tokens = { + {Opt_uid, "uid=%u"}, + {Opt_gid, "gid=%u"}, + {Opt_mode, "mode=%o"}, + {Opt_err, NULL} +}; + +struct debugfs_fs_info { + struct debugfs_mount_opts mount_opts; +}; + +static int debugfs_parse_options(char *data, struct debugfs_mount_opts *opts) +{ + substring_t args[MAX_OPT_ARGS]; + int option; + int token; + kuid_t uid; + kgid_t gid; + char *p; + + opts->opts = 0; + opts->mode = DEBUGFS_DEFAULT_MODE; + + while ((p = strsep(&data, ",")) != NULL) { + if (!*p) + continue; + + token = match_token(p, tokens, args); + switch (token) { + case Opt_uid: + if (match_int(&args[0], &option)) + return -EINVAL; + uid = make_kuid(current_user_ns(), option); + if (!uid_valid(uid)) + return -EINVAL; + opts->uid = uid; + break; + case Opt_gid: + if (match_int(&args[0], &option)) + return -EINVAL; + gid = make_kgid(current_user_ns(), option); + if (!gid_valid(gid)) + return -EINVAL; + opts->gid = gid; + break; + case Opt_mode: + if (match_octal(&args[0], &option)) + return -EINVAL; + opts->mode = option & S_IALLUGO; + break; + /* + * We might like to report bad mount options here; + * but traditionally debugfs has ignored all mount options + */ + } + + opts->opts |= BIT(token); + } + + return 0; +} + +static void _debugfs_apply_options(struct super_block *sb, bool remount) +{ + struct debugfs_fs_info *fsi = sb->s_fs_info; + struct inode *inode = d_inode(sb->s_root); + struct debugfs_mount_opts *opts = &fsi->mount_opts; + + /* + * On remount, only reset mode/uid/gid if they were provided as mount + * options. + */ + + if (!remount || opts->opts & BIT(Opt_mode)) { + inode->i_mode &= ~S_IALLUGO; + inode->i_mode |= opts->mode; + } + + if (!remount || opts->opts & BIT(Opt_uid)) + inode->i_uid = opts->uid; + + if (!remount || opts->opts & BIT(Opt_gid)) + inode->i_gid = opts->gid; +} + +static void debugfs_apply_options(struct super_block *sb) +{ + _debugfs_apply_options(sb, false); +} + +static void debugfs_apply_options_remount(struct super_block *sb) +{ + _debugfs_apply_options(sb, true); +} + +static int debugfs_remount(struct super_block *sb, int *flags, char *data) +{ + int err; + struct debugfs_fs_info *fsi = sb->s_fs_info; + + sync_filesystem(sb); + err = debugfs_parse_options(data, &fsi->mount_opts); + if (err) + goto fail; + + debugfs_apply_options_remount(sb); + +fail: + return err; +} + +static int debugfs_show_options(struct seq_file *m, struct dentry *root) +{ + struct debugfs_fs_info *fsi = root->d_sb->s_fs_info; + struct debugfs_mount_opts *opts = &fsi->mount_opts; + + if (!uid_eq(opts->uid, GLOBAL_ROOT_UID)) + seq_printf(m, ",uid=%u", + from_kuid_munged(&init_user_ns, opts->uid)); + if (!gid_eq(opts->gid, GLOBAL_ROOT_GID)) + seq_printf(m, ",gid=%u", + from_kgid_munged(&init_user_ns, opts->gid)); + if (opts->mode != DEBUGFS_DEFAULT_MODE) + seq_printf(m, ",mode=%o", opts->mode); + + return 0; +} + +static void debugfs_free_inode(struct inode *inode) +{ + if (S_ISLNK(inode->i_mode)) + kfree(inode->i_link); + free_inode_nonrcu(inode); +} + +static const struct super_operations debugfs_super_operations = { + .statfs = simple_statfs, + .remount_fs = debugfs_remount, + .show_options = debugfs_show_options, + .free_inode = debugfs_free_inode, +}; + +static void debugfs_release_dentry(struct dentry *dentry) +{ + struct debugfs_fsdata *fsd = dentry->d_fsdata; + + if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT) + return; + + kfree(fsd); +} + +static struct vfsmount *debugfs_automount(struct path *path) +{ + struct debugfs_fsdata *fsd = path->dentry->d_fsdata; + + return fsd->automount(path->dentry, d_inode(path->dentry)->i_private); +} + +static const struct dentry_operations debugfs_dops = { + .d_delete = always_delete_dentry, + .d_release = debugfs_release_dentry, + .d_automount = debugfs_automount, +}; + +static int debug_fill_super(struct super_block *sb, void *data, int silent) +{ + static const struct tree_descr debug_files[] = {{""}}; + struct debugfs_fs_info *fsi; + int err; + + fsi = kzalloc(sizeof(struct debugfs_fs_info), GFP_KERNEL); + sb->s_fs_info = fsi; + if (!fsi) { + err = -ENOMEM; + goto fail; + } + + err = debugfs_parse_options(data, &fsi->mount_opts); + if (err) + goto fail; + + err = simple_fill_super(sb, DEBUGFS_MAGIC, debug_files); + if (err) + goto fail; + + sb->s_op = &debugfs_super_operations; + sb->s_d_op = &debugfs_dops; + + debugfs_apply_options(sb); + + return 0; + +fail: + kfree(fsi); + sb->s_fs_info = NULL; + return err; +} + +static struct dentry *debug_mount(struct file_system_type *fs_type, + int flags, const char *dev_name, + void *data) +{ + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) + return ERR_PTR(-EPERM); + + return mount_single(fs_type, flags, data, debug_fill_super); +} + +static struct file_system_type debug_fs_type = { + .owner = THIS_MODULE, + .name = "debugfs", + .mount = debug_mount, + .kill_sb = kill_litter_super, +}; +MODULE_ALIAS_FS("debugfs"); + +/** + * debugfs_lookup() - look up an existing debugfs file + * @name: a pointer to a string containing the name of the file to look up. + * @parent: a pointer to the parent dentry of the file. + * + * This function will return a pointer to a dentry if it succeeds. If the file + * doesn't exist or an error occurs, %NULL will be returned. The returned + * dentry must be passed to dput() when it is no longer needed. + * + * If debugfs is not enabled in the kernel, the value -%ENODEV will be + * returned. + */ +struct dentry *debugfs_lookup(const char *name, struct dentry *parent) +{ + struct dentry *dentry; + + if (!debugfs_initialized() || IS_ERR_OR_NULL(name) || IS_ERR(parent)) + return NULL; + + if (!parent) + parent = debugfs_mount->mnt_root; + + dentry = lookup_positive_unlocked(name, parent, strlen(name)); + if (IS_ERR(dentry)) + return NULL; + return dentry; +} +EXPORT_SYMBOL_GPL(debugfs_lookup); + +static struct dentry *start_creating(const char *name, struct dentry *parent) +{ + struct dentry *dentry; + int error; + + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) + return ERR_PTR(-EPERM); + + if (!debugfs_initialized()) + return ERR_PTR(-ENOENT); + + pr_debug("creating file '%s'\n", name); + + if (IS_ERR(parent)) + return parent; + + error = simple_pin_fs(&debug_fs_type, &debugfs_mount, + &debugfs_mount_count); + if (error) { + pr_err("Unable to pin filesystem for file '%s'\n", name); + return ERR_PTR(error); + } + + /* 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. + */ + if (!parent) + parent = debugfs_mount->mnt_root; + + inode_lock(d_inode(parent)); + if (unlikely(IS_DEADDIR(d_inode(parent)))) + dentry = ERR_PTR(-ENOENT); + else + dentry = lookup_one_len(name, parent, strlen(name)); + if (!IS_ERR(dentry) && d_really_is_positive(dentry)) { + if (d_is_dir(dentry)) + pr_err("Directory '%s' with parent '%s' already present!\n", + name, parent->d_name.name); + else + pr_err("File '%s' in directory '%s' already present!\n", + name, parent->d_name.name); + dput(dentry); + dentry = ERR_PTR(-EEXIST); + } + + if (IS_ERR(dentry)) { + inode_unlock(d_inode(parent)); + simple_release_fs(&debugfs_mount, &debugfs_mount_count); + } + + return dentry; +} + +static struct dentry *failed_creating(struct dentry *dentry) +{ + inode_unlock(d_inode(dentry->d_parent)); + dput(dentry); + simple_release_fs(&debugfs_mount, &debugfs_mount_count); + return ERR_PTR(-ENOMEM); +} + +static struct dentry *end_creating(struct dentry *dentry) +{ + inode_unlock(d_inode(dentry->d_parent)); + return dentry; +} + +static struct dentry *__debugfs_create_file(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *proxy_fops, + const struct file_operations *real_fops) +{ + struct dentry *dentry; + struct inode *inode; + + if (!(mode & S_IFMT)) + mode |= S_IFREG; + BUG_ON(!S_ISREG(mode)); + dentry = start_creating(name, parent); + + if (IS_ERR(dentry)) + return dentry; + + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) { + failed_creating(dentry); + return ERR_PTR(-EPERM); + } + + inode = debugfs_get_inode(dentry->d_sb); + if (unlikely(!inode)) { + pr_err("out of free dentries, can not create file '%s'\n", + name); + return failed_creating(dentry); + } + + inode->i_mode = mode; + inode->i_private = data; + + inode->i_op = &debugfs_file_inode_operations; + inode->i_fop = proxy_fops; + dentry->d_fsdata = (void *)((unsigned long)real_fops | + DEBUGFS_FSDATA_IS_REAL_FOPS_BIT); + + d_instantiate(dentry, inode); + fsnotify_create(d_inode(dentry->d_parent), dentry); + return end_creating(dentry); +} + +/** + * debugfs_create_file - create a file in the debugfs 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 debugfs 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 is the basic "create a file" function for debugfs. It allows for a + * wide range of flexibility in creating a file, or a directory (if you want + * to create a directory, the debugfs_create_dir() function is + * recommended to be used instead.) + * + * This function will return a pointer to a dentry if it succeeds. This + * pointer must be passed to the debugfs_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, ERR_PTR(-ERROR) will be + * returned. + * + * If debugfs is not enabled in the kernel, the value -%ENODEV will be + * returned. + * + * NOTE: it's expected that most callers should _ignore_ the errors returned + * by this function. Other debugfs functions handle the fact that the "dentry" + * passed to them could be an error and they don't crash in that case. + * Drivers should generally work fine even if debugfs fails to init anyway. + */ +struct dentry *debugfs_create_file(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops) +{ + + return __debugfs_create_file(name, mode, parent, data, + fops ? &debugfs_full_proxy_file_operations : + &debugfs_noop_file_operations, + fops); +} +EXPORT_SYMBOL_GPL(debugfs_create_file); + +/** + * debugfs_create_file_unsafe - create a file in the debugfs 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 debugfs 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. + * + * debugfs_create_file_unsafe() is completely analogous to + * debugfs_create_file(), the only difference being that the fops + * handed it will not get protected against file removals by the + * debugfs core. + * + * It is your responsibility to protect your struct file_operation + * methods against file removals by means of debugfs_file_get() + * and debugfs_file_put(). ->open() is still protected by + * debugfs though. + * + * Any struct file_operations defined by means of + * DEFINE_DEBUGFS_ATTRIBUTE() is protected against file removals and + * thus, may be used here. + */ +struct dentry *debugfs_create_file_unsafe(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops) +{ + + return __debugfs_create_file(name, mode, parent, data, + fops ? &debugfs_open_proxy_file_operations : + &debugfs_noop_file_operations, + fops); +} +EXPORT_SYMBOL_GPL(debugfs_create_file_unsafe); + +/** + * debugfs_create_file_size - create a file in the debugfs 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 debugfs 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. + * @file_size: initial file size + * + * This is the basic "create a file" function for debugfs. It allows for a + * wide range of flexibility in creating a file, or a directory (if you want + * to create a directory, the debugfs_create_dir() function is + * recommended to be used instead.) + */ +void debugfs_create_file_size(const char *name, umode_t mode, + struct dentry *parent, void *data, + const struct file_operations *fops, + loff_t file_size) +{ + struct dentry *de = debugfs_create_file(name, mode, parent, data, fops); + + if (!IS_ERR(de)) + d_inode(de)->i_size = file_size; +} +EXPORT_SYMBOL_GPL(debugfs_create_file_size); + +/** + * debugfs_create_dir - create a directory in the debugfs 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 debugfs filesystem. + * + * This function creates a directory in debugfs with the given name. + * + * This function will return a pointer to a dentry if it succeeds. This + * pointer must be passed to the debugfs_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, ERR_PTR(-ERROR) will be + * returned. + * + * If debugfs is not enabled in the kernel, the value -%ENODEV will be + * returned. + * + * NOTE: it's expected that most callers should _ignore_ the errors returned + * by this function. Other debugfs functions handle the fact that the "dentry" + * passed to them could be an error and they don't crash in that case. + * Drivers should generally work fine even if debugfs fails to init anyway. + */ +struct dentry *debugfs_create_dir(const char *name, struct dentry *parent) +{ + struct dentry *dentry = start_creating(name, parent); + struct inode *inode; + + if (IS_ERR(dentry)) + return dentry; + + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) { + failed_creating(dentry); + return ERR_PTR(-EPERM); + } + + inode = debugfs_get_inode(dentry->d_sb); + if (unlikely(!inode)) { + pr_err("out of free dentries, can not create directory '%s'\n", + name); + return failed_creating(dentry); + } + + inode->i_mode = S_IFDIR | S_IRWXU | S_IRUGO | S_IXUGO; + inode->i_op = &debugfs_dir_inode_operations; + inode->i_fop = &simple_dir_operations; + + /* directory inodes start off with i_nlink == 2 (for "." entry) */ + inc_nlink(inode); + d_instantiate(dentry, inode); + inc_nlink(d_inode(dentry->d_parent)); + fsnotify_mkdir(d_inode(dentry->d_parent), dentry); + return end_creating(dentry); +} +EXPORT_SYMBOL_GPL(debugfs_create_dir); + +/** + * debugfs_create_automount - create automount point in the debugfs filesystem + * @name: a pointer to a string containing the name of the file 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 + * file will be created in the root of the debugfs filesystem. + * @f: function to be called when pathname resolution steps on that one. + * @data: opaque argument to pass to f(). + * + * @f should return what ->d_automount() would. + */ +struct dentry *debugfs_create_automount(const char *name, + struct dentry *parent, + debugfs_automount_t f, + void *data) +{ + struct dentry *dentry = start_creating(name, parent); + struct debugfs_fsdata *fsd; + struct inode *inode; + + if (IS_ERR(dentry)) + return dentry; + + fsd = kzalloc(sizeof(*fsd), GFP_KERNEL); + if (!fsd) { + failed_creating(dentry); + return ERR_PTR(-ENOMEM); + } + + fsd->automount = f; + + if (!(debugfs_allow & DEBUGFS_ALLOW_API)) { + failed_creating(dentry); + kfree(fsd); + return ERR_PTR(-EPERM); + } + + inode = debugfs_get_inode(dentry->d_sb); + if (unlikely(!inode)) { + pr_err("out of free dentries, can not create automount '%s'\n", + name); + kfree(fsd); + return failed_creating(dentry); + } + + make_empty_dir_inode(inode); + inode->i_flags |= S_AUTOMOUNT; + inode->i_private = data; + dentry->d_fsdata = fsd; + /* directory inodes start off with i_nlink == 2 (for "." entry) */ + inc_nlink(inode); + d_instantiate(dentry, inode); + inc_nlink(d_inode(dentry->d_parent)); + fsnotify_mkdir(d_inode(dentry->d_parent), dentry); + return end_creating(dentry); +} +EXPORT_SYMBOL(debugfs_create_automount); + +/** + * debugfs_create_symlink- create a symbolic link in the debugfs filesystem + * @name: a pointer to a string containing the name of the symbolic link to + * create. + * @parent: a pointer to the parent dentry for this symbolic link. This + * should be a directory dentry if set. If this parameter is NULL, + * then the symbolic link will be created in the root of the debugfs + * filesystem. + * @target: a pointer to a string containing the path to the target of the + * symbolic link. + * + * This function creates a symbolic link with the given name in debugfs that + * links to the given target path. + * + * This function will return a pointer to a dentry if it succeeds. This + * pointer must be passed to the debugfs_remove() function when the symbolic + * link is to be removed (no automatic cleanup happens if your module is + * unloaded, you are responsible here.) If an error occurs, ERR_PTR(-ERROR) + * will be returned. + * + * If debugfs is not enabled in the kernel, the value -%ENODEV will be + * returned. + */ +struct dentry *debugfs_create_symlink(const char *name, struct dentry *parent, + const char *target) +{ + struct dentry *dentry; + struct inode *inode; + char *link = kstrdup(target, GFP_KERNEL); + if (!link) + return ERR_PTR(-ENOMEM); + + dentry = start_creating(name, parent); + if (IS_ERR(dentry)) { + kfree(link); + return dentry; + } + + inode = debugfs_get_inode(dentry->d_sb); + if (unlikely(!inode)) { + pr_err("out of free dentries, can not create symlink '%s'\n", + name); + kfree(link); + return failed_creating(dentry); + } + inode->i_mode = S_IFLNK | S_IRWXUGO; + inode->i_op = &debugfs_symlink_inode_operations; + inode->i_link = link; + d_instantiate(dentry, inode); + return end_creating(dentry); +} +EXPORT_SYMBOL_GPL(debugfs_create_symlink); + +static void __debugfs_file_removed(struct dentry *dentry) +{ + struct debugfs_fsdata *fsd; + + /* + * Paired with the closing smp_mb() implied by a successful + * cmpxchg() in debugfs_file_get(): either + * debugfs_file_get() must see a dead dentry or we must see a + * debugfs_fsdata instance at ->d_fsdata here (or both). + */ + smp_mb(); + fsd = READ_ONCE(dentry->d_fsdata); + if ((unsigned long)fsd & DEBUGFS_FSDATA_IS_REAL_FOPS_BIT) + return; + if (!refcount_dec_and_test(&fsd->active_users)) + wait_for_completion(&fsd->active_users_drained); +} + +static void remove_one(struct dentry *victim) +{ + if (d_is_reg(victim)) + __debugfs_file_removed(victim); + simple_release_fs(&debugfs_mount, &debugfs_mount_count); +} + +/** + * debugfs_remove - recursively removes a directory + * @dentry: a pointer to a the dentry of the directory to be removed. If this + * parameter is NULL or an error value, nothing will be done. + * + * This function recursively removes a directory tree in debugfs that + * was previously created with a call to another debugfs function + * (like debugfs_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 debugfs_remove(struct dentry *dentry) +{ + if (IS_ERR_OR_NULL(dentry)) + return; + + simple_pin_fs(&debug_fs_type, &debugfs_mount, &debugfs_mount_count); + simple_recursive_removal(dentry, remove_one); + simple_release_fs(&debugfs_mount, &debugfs_mount_count); +} +EXPORT_SYMBOL_GPL(debugfs_remove); + +/** + * debugfs_lookup_and_remove - lookup a directory or file and recursively remove it + * @name: a pointer to a string containing the name of the item to look up. + * @parent: a pointer to the parent dentry of the item. + * + * This is the equlivant of doing something like + * debugfs_remove(debugfs_lookup(..)) but with the proper reference counting + * handled for the directory being looked up. + */ +void debugfs_lookup_and_remove(const char *name, struct dentry *parent) +{ + struct dentry *dentry; + + dentry = debugfs_lookup(name, parent); + if (!dentry) + return; + + debugfs_remove(dentry); + dput(dentry); +} +EXPORT_SYMBOL_GPL(debugfs_lookup_and_remove); + +/** + * debugfs_rename - rename a file/directory in the debugfs filesystem + * @old_dir: a pointer to the parent dentry for the renamed object. This + * should be a directory dentry. + * @old_dentry: dentry of an object to be renamed. + * @new_dir: a pointer to the parent dentry where the object should be + * moved. This should be a directory dentry. + * @new_name: a pointer to a string containing the target name. + * + * This function renames a file/directory in debugfs. The target must not + * exist for rename to succeed. + * + * This function will return a pointer to old_dentry (which is updated to + * reflect renaming) if it succeeds. If an error occurs, %NULL will be + * returned. + * + * If debugfs is not enabled in the kernel, the value -%ENODEV will be + * returned. + */ +struct dentry *debugfs_rename(struct dentry *old_dir, struct dentry *old_dentry, + struct dentry *new_dir, const char *new_name) +{ + int error; + struct dentry *dentry = NULL, *trap; + struct name_snapshot old_name; + + if (IS_ERR(old_dir)) + return old_dir; + if (IS_ERR(new_dir)) + return new_dir; + if (IS_ERR_OR_NULL(old_dentry)) + return old_dentry; + + trap = lock_rename(new_dir, old_dir); + /* Source or destination directories don't exist? */ + if (d_really_is_negative(old_dir) || d_really_is_negative(new_dir)) + goto exit; + /* Source does not exist, cyclic rename, or mountpoint? */ + if (d_really_is_negative(old_dentry) || old_dentry == trap || + d_mountpoint(old_dentry)) + goto exit; + dentry = lookup_one_len(new_name, new_dir, strlen(new_name)); + /* Lookup failed, cyclic rename or target exists? */ + if (IS_ERR(dentry) || dentry == trap || d_really_is_positive(dentry)) + goto exit; + + take_dentry_name_snapshot(&old_name, old_dentry); + + error = simple_rename(&init_user_ns, d_inode(old_dir), old_dentry, + d_inode(new_dir), dentry, 0); + if (error) { + release_dentry_name_snapshot(&old_name); + goto exit; + } + d_move(old_dentry, dentry); + fsnotify_move(d_inode(old_dir), d_inode(new_dir), &old_name.name, + d_is_dir(old_dentry), + NULL, old_dentry); + release_dentry_name_snapshot(&old_name); + unlock_rename(new_dir, old_dir); + dput(dentry); + return old_dentry; +exit: + if (dentry && !IS_ERR(dentry)) + dput(dentry); + unlock_rename(new_dir, old_dir); + if (IS_ERR(dentry)) + return dentry; + return ERR_PTR(-EINVAL); +} +EXPORT_SYMBOL_GPL(debugfs_rename); + +/** + * debugfs_initialized - Tells whether debugfs has been registered + */ +bool debugfs_initialized(void) +{ + return debugfs_registered; +} +EXPORT_SYMBOL_GPL(debugfs_initialized); + +static int __init debugfs_kernel(char *str) +{ + if (str) { + if (!strcmp(str, "on")) + debugfs_allow = DEBUGFS_ALLOW_API | DEBUGFS_ALLOW_MOUNT; + else if (!strcmp(str, "no-mount")) + debugfs_allow = DEBUGFS_ALLOW_API; + else if (!strcmp(str, "off")) + debugfs_allow = 0; + } + + return 0; +} +early_param("debugfs", debugfs_kernel); +static int __init debugfs_init(void) +{ + int retval; + + if (!(debugfs_allow & DEBUGFS_ALLOW_MOUNT)) + return -EPERM; + + retval = sysfs_create_mount_point(kernel_kobj, "debug"); + if (retval) + return retval; + + retval = register_filesystem(&debug_fs_type); + if (retval) + sysfs_remove_mount_point(kernel_kobj, "debug"); + else + debugfs_registered = true; + + return retval; +} +core_initcall(debugfs_init); |