linux/fs/sysfs/file.c

// SPDX-License-Identifier: GPL-2.0
/*
 * fs/sysfs/file.c - sysfs regular (text) file implementation
 *
 * Copyright (c) 2001-3 Patrick Mochel
 * Copyright (c) 2007 SUSE Linux Products GmbH
 * Copyright (c) 2007 Tejun Heo <[email protected]>
 *
 * Please see Documentation/filesystems/sysfs.rst for more information.
 */

#include <linux/module.h>
#include <linux/kobject.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/mutex.h>
#include <linux/seq_file.h>
#include <linux/mm.h>

#include "sysfs.h"

/*
 * Determine ktype->sysfs_ops for the given kernfs_node.  This function
 * must be called while holding an active reference.
 */
static const struct sysfs_ops *sysfs_file_ops(struct kernfs_node *kn)
{ … }

/*
 * Reads on sysfs are handled through seq_file, which takes care of hairy
 * details like buffering and seeking.  The following function pipes
 * sysfs_ops->show() result through seq_file.
 */
static int sysfs_kf_seq_show(struct seq_file *sf, void *v)
{ … }

static ssize_t sysfs_kf_bin_read(struct kernfs_open_file *of, char *buf,
				 size_t count, loff_t pos)
{ … }

/* kernfs read callback for regular sysfs files with pre-alloc */
static ssize_t sysfs_kf_read(struct kernfs_open_file *of, char *buf,
			     size_t count, loff_t pos)
{ … }

/* kernfs write callback for regular sysfs files */
static ssize_t sysfs_kf_write(struct kernfs_open_file *of, char *buf,
			      size_t count, loff_t pos)
{ … }

/* kernfs write callback for bin sysfs files */
static ssize_t sysfs_kf_bin_write(struct kernfs_open_file *of, char *buf,
				  size_t count, loff_t pos)
{ … }

static int sysfs_kf_bin_mmap(struct kernfs_open_file *of,
			     struct vm_area_struct *vma)
{ … }

static loff_t sysfs_kf_bin_llseek(struct kernfs_open_file *of, loff_t offset,
				  int whence)
{ … }

static int sysfs_kf_bin_open(struct kernfs_open_file *of)
{ … }

void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr)
{ … }
EXPORT_SYMBOL_GPL(…);

static const struct kernfs_ops sysfs_file_kfops_empty = …;

static const struct kernfs_ops sysfs_file_kfops_ro = …;

static const struct kernfs_ops sysfs_file_kfops_wo = …;

static const struct kernfs_ops sysfs_file_kfops_rw = …;

static const struct kernfs_ops sysfs_prealloc_kfops_ro = …;

static const struct kernfs_ops sysfs_prealloc_kfops_wo = …;

static const struct kernfs_ops sysfs_prealloc_kfops_rw = …;

static const struct kernfs_ops sysfs_bin_kfops_ro = …;

static const struct kernfs_ops sysfs_bin_kfops_wo = …;

static const struct kernfs_ops sysfs_bin_kfops_rw = …;

static const struct kernfs_ops sysfs_bin_kfops_mmap = …;

int sysfs_add_file_mode_ns(struct kernfs_node *parent,
		const struct attribute *attr, umode_t mode, kuid_t uid,
		kgid_t gid, const void *ns)
{ … }

int sysfs_add_bin_file_mode_ns(struct kernfs_node *parent,
		const struct bin_attribute *battr, umode_t mode,
		kuid_t uid, kgid_t gid, const void *ns)
{ … }

/**
 * sysfs_create_file_ns - create an attribute file for an object with custom ns
 * @kobj: object we're creating for
 * @attr: attribute descriptor
 * @ns: namespace the new file should belong to
 */
int sysfs_create_file_ns(struct kobject *kobj, const struct attribute *attr,
			 const void *ns)
{ … }
EXPORT_SYMBOL_GPL(…);

int sysfs_create_files(struct kobject *kobj, const struct attribute * const *ptr)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * sysfs_add_file_to_group - add an attribute file to a pre-existing group.
 * @kobj: object we're acting for.
 * @attr: attribute descriptor.
 * @group: group name.
 */
int sysfs_add_file_to_group(struct kobject *kobj,
		const struct attribute *attr, const char *group)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * sysfs_chmod_file - update the modified mode value on an object attribute.
 * @kobj: object we're acting for.
 * @attr: attribute descriptor.
 * @mode: file permissions.
 *
 */
int sysfs_chmod_file(struct kobject *kobj, const struct attribute *attr,
		     umode_t mode)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * sysfs_break_active_protection - break "active" protection
 * @kobj: The kernel object @attr is associated with.
 * @attr: The attribute to break the "active" protection for.
 *
 * With sysfs, just like kernfs, deletion of an attribute is postponed until
 * all active .show() and .store() callbacks have finished unless this function
 * is called. Hence this function is useful in methods that implement self
 * deletion.
 */
struct kernfs_node *sysfs_break_active_protection(struct kobject *kobj,
						  const struct attribute *attr)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * sysfs_unbreak_active_protection - restore "active" protection
 * @kn: Pointer returned by sysfs_break_active_protection().
 *
 * Undo the effects of sysfs_break_active_protection(). Since this function
 * calls kernfs_put() on the kernfs node that corresponds to the 'attr'
 * argument passed to sysfs_break_active_protection() that attribute may have
 * been removed between the sysfs_break_active_protection() and
 * sysfs_unbreak_active_protection() calls, it is not safe to access @kn after
 * this function has returned.
 */
void sysfs_unbreak_active_protection(struct kernfs_node *kn)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * sysfs_remove_file_ns - remove an object attribute with a custom ns tag
 * @kobj: object we're acting for
 * @attr: attribute descriptor
 * @ns: namespace tag of the file to remove
 *
 * Hash the attribute name and namespace tag and kill the victim.
 */
void sysfs_remove_file_ns(struct kobject *kobj, const struct attribute *attr,
			  const void *ns)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * sysfs_remove_file_self - remove an object attribute from its own method
 * @kobj: object we're acting for
 * @attr: attribute descriptor
 *
 * See kernfs_remove_self() for details.
 */
bool sysfs_remove_file_self(struct kobject *kobj, const struct attribute *attr)
{ … }
EXPORT_SYMBOL_GPL(…);

void sysfs_remove_files(struct kobject *kobj, const struct attribute * const *ptr)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 * sysfs_remove_file_from_group - remove an attribute file from a group.
 * @kobj: object we're acting for.
 * @attr: attribute descriptor.
 * @group: group name.
 */
void sysfs_remove_file_from_group(struct kobject *kobj,
		const struct attribute *attr, const char *group)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 *	sysfs_create_bin_file - create binary file for object.
 *	@kobj:	object.
 *	@attr:	attribute descriptor.
 */
int sysfs_create_bin_file(struct kobject *kobj,
			  const struct bin_attribute *attr)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 *	sysfs_remove_bin_file - remove binary file for object.
 *	@kobj:	object.
 *	@attr:	attribute descriptor.
 */
void sysfs_remove_bin_file(struct kobject *kobj,
			   const struct bin_attribute *attr)
{ … }
EXPORT_SYMBOL_GPL(…);

static int internal_change_owner(struct kernfs_node *kn, kuid_t kuid,
				 kgid_t kgid)
{ … }

/**
 *	sysfs_link_change_owner - change owner of a sysfs file.
 *	@kobj:	object of the kernfs_node the symlink is located in.
 *	@targ:	object of the kernfs_node the symlink points to.
 *	@name:	name of the link.
 *	@kuid:	new owner's kuid
 *	@kgid:	new owner's kgid
 *
 * This function looks up the sysfs symlink entry @name under @kobj and changes
 * the ownership to @kuid/@kgid. The symlink is looked up in the namespace of
 * @targ.
 *
 * Returns 0 on success or error code on failure.
 */
int sysfs_link_change_owner(struct kobject *kobj, struct kobject *targ,
			    const char *name, kuid_t kuid, kgid_t kgid)
{ … }

/**
 *	sysfs_file_change_owner - change owner of a sysfs file.
 *	@kobj:	object.
 *	@name:	name of the file to change.
 *	@kuid:	new owner's kuid
 *	@kgid:	new owner's kgid
 *
 * This function looks up the sysfs entry @name under @kobj and changes the
 * ownership to @kuid/@kgid.
 *
 * Returns 0 on success or error code on failure.
 */
int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid,
			    kgid_t kgid)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 *	sysfs_change_owner - change owner of the given object.
 *	@kobj:	object.
 *	@kuid:	new owner's kuid
 *	@kgid:	new owner's kgid
 *
 * Change the owner of the default directory, files, groups, and attributes of
 * @kobj to @kuid/@kgid. Note that sysfs_change_owner mirrors how the sysfs
 * entries for a kobject are added by driver core. In summary,
 * sysfs_change_owner() takes care of the default directory entry for @kobj,
 * the default attributes associated with the ktype of @kobj and the default
 * attributes associated with the ktype of @kobj.
 * Additional properties not added by driver core have to be changed by the
 * driver or subsystem which created them. This is similar to how
 * driver/subsystem specific entries are removed.
 *
 * Returns 0 on success or error code on failure.
 */
int sysfs_change_owner(struct kobject *kobj, kuid_t kuid, kgid_t kgid)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 *	sysfs_emit - scnprintf equivalent, aware of PAGE_SIZE buffer.
 *	@buf:	start of PAGE_SIZE buffer.
 *	@fmt:	format
 *	@...:	optional arguments to @format
 *
 *
 * Returns number of characters written to @buf.
 */
int sysfs_emit(char *buf, const char *fmt, ...)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 *	sysfs_emit_at - scnprintf equivalent, aware of PAGE_SIZE buffer.
 *	@buf:	start of PAGE_SIZE buffer.
 *	@at:	offset in @buf to start write in bytes
 *		@at must be >= 0 && < PAGE_SIZE
 *	@fmt:	format
 *	@...:	optional arguments to @fmt
 *
 *
 * Returns number of characters written starting at &@buf[@at].
 */
int sysfs_emit_at(char *buf, int at, const char *fmt, ...)
{ … }
EXPORT_SYMBOL_GPL(…);

/**
 *	sysfs_bin_attr_simple_read - read callback to simply copy from memory.
 *	@file:	attribute file which is being read.
 *	@kobj:	object to which the attribute belongs.
 *	@attr:	attribute descriptor.
 *	@buf:	destination buffer.
 *	@off:	offset in bytes from which to read.
 *	@count:	maximum number of bytes to read.
 *
 * Simple ->read() callback for bin_attributes backed by a buffer in memory.
 * The @private and @size members in struct bin_attribute must be set to the
 * buffer's location and size before the bin_attribute is created in sysfs.
 *
 * Bounds check for @off and @count is done in sysfs_kf_bin_read().
 * Negative value check for @off is done in vfs_setpos() and default_llseek().
 *
 * Returns number of bytes written to @buf.
 */
ssize_t sysfs_bin_attr_simple_read(struct file *file, struct kobject *kobj,
				   struct bin_attribute *attr, char *buf,
				   loff_t off, size_t count)
{ … }
EXPORT_SYMBOL_GPL(…);