linux/fs/sysfs/group.c
Christian Brauner 303a42769c sysfs: add sysfs_group{s}_change_owner()
Add helpers to change the owner of sysfs groups.
This function will be used to correctly account for kobject ownership
changes, e.g. when moving network devices between network namespaces.

Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-02-26 20:07:25 -08:00

575 lines
15 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* fs/sysfs/group.c - Operations for adding/removing multiple files at once.
*
* Copyright (c) 2003 Patrick Mochel
* Copyright (c) 2003 Open Source Development Lab
* Copyright (c) 2013 Greg Kroah-Hartman
* Copyright (c) 2013 The Linux Foundation
*/
#include <linux/kobject.h>
#include <linux/module.h>
#include <linux/dcache.h>
#include <linux/namei.h>
#include <linux/err.h>
#include <linux/fs.h>
#include "sysfs.h"
static void remove_files(struct kernfs_node *parent,
const struct attribute_group *grp)
{
struct attribute *const *attr;
struct bin_attribute *const *bin_attr;
if (grp->attrs)
for (attr = grp->attrs; *attr; attr++)
kernfs_remove_by_name(parent, (*attr)->name);
if (grp->bin_attrs)
for (bin_attr = grp->bin_attrs; *bin_attr; bin_attr++)
kernfs_remove_by_name(parent, (*bin_attr)->attr.name);
}
static int create_files(struct kernfs_node *parent, struct kobject *kobj,
kuid_t uid, kgid_t gid,
const struct attribute_group *grp, int update)
{
struct attribute *const *attr;
struct bin_attribute *const *bin_attr;
int error = 0, i;
if (grp->attrs) {
for (i = 0, attr = grp->attrs; *attr && !error; i++, attr++) {
umode_t mode = (*attr)->mode;
/*
* In update mode, we're changing the permissions or
* visibility. Do this by first removing then
* re-adding (if required) the file.
*/
if (update)
kernfs_remove_by_name(parent, (*attr)->name);
if (grp->is_visible) {
mode = grp->is_visible(kobj, *attr, i);
if (!mode)
continue;
}
WARN(mode & ~(SYSFS_PREALLOC | 0664),
"Attribute %s: Invalid permissions 0%o\n",
(*attr)->name, mode);
mode &= SYSFS_PREALLOC | 0664;
error = sysfs_add_file_mode_ns(parent, *attr, false,
mode, uid, gid, NULL);
if (unlikely(error))
break;
}
if (error) {
remove_files(parent, grp);
goto exit;
}
}
if (grp->bin_attrs) {
for (i = 0, bin_attr = grp->bin_attrs; *bin_attr; i++, bin_attr++) {
umode_t mode = (*bin_attr)->attr.mode;
if (update)
kernfs_remove_by_name(parent,
(*bin_attr)->attr.name);
if (grp->is_bin_visible) {
mode = grp->is_bin_visible(kobj, *bin_attr, i);
if (!mode)
continue;
}
WARN(mode & ~(SYSFS_PREALLOC | 0664),
"Attribute %s: Invalid permissions 0%o\n",
(*bin_attr)->attr.name, mode);
mode &= SYSFS_PREALLOC | 0664;
error = sysfs_add_file_mode_ns(parent,
&(*bin_attr)->attr, true,
mode,
uid, gid, NULL);
if (error)
break;
}
if (error)
remove_files(parent, grp);
}
exit:
return error;
}
static int internal_create_group(struct kobject *kobj, int update,
const struct attribute_group *grp)
{
struct kernfs_node *kn;
kuid_t uid;
kgid_t gid;
int error;
if (WARN_ON(!kobj || (!update && !kobj->sd)))
return -EINVAL;
/* Updates may happen before the object has been instantiated */
if (unlikely(update && !kobj->sd))
return -EINVAL;
if (!grp->attrs && !grp->bin_attrs) {
WARN(1, "sysfs: (bin_)attrs not set by subsystem for group: %s/%s\n",
kobj->name, grp->name ?: "");
return -EINVAL;
}
kobject_get_ownership(kobj, &uid, &gid);
if (grp->name) {
if (update) {
kn = kernfs_find_and_get(kobj->sd, grp->name);
if (!kn) {
pr_warn("Can't update unknown attr grp name: %s/%s\n",
kobj->name, grp->name);
return -EINVAL;
}
} else {
kn = kernfs_create_dir_ns(kobj->sd, grp->name,
S_IRWXU | S_IRUGO | S_IXUGO,
uid, gid, kobj, NULL);
if (IS_ERR(kn)) {
if (PTR_ERR(kn) == -EEXIST)
sysfs_warn_dup(kobj->sd, grp->name);
return PTR_ERR(kn);
}
}
} else
kn = kobj->sd;
kernfs_get(kn);
error = create_files(kn, kobj, uid, gid, grp, update);
if (error) {
if (grp->name)
kernfs_remove(kn);
}
kernfs_put(kn);
if (grp->name && update)
kernfs_put(kn);
return error;
}
/**
* sysfs_create_group - given a directory kobject, create an attribute group
* @kobj: The kobject to create the group on
* @grp: The attribute group to create
*
* This function creates a group for the first time. It will explicitly
* warn and error if any of the attribute files being created already exist.
*
* Returns 0 on success or error code on failure.
*/
int sysfs_create_group(struct kobject *kobj,
const struct attribute_group *grp)
{
return internal_create_group(kobj, 0, grp);
}
EXPORT_SYMBOL_GPL(sysfs_create_group);
static int internal_create_groups(struct kobject *kobj, int update,
const struct attribute_group **groups)
{
int error = 0;
int i;
if (!groups)
return 0;
for (i = 0; groups[i]; i++) {
error = internal_create_group(kobj, update, groups[i]);
if (error) {
while (--i >= 0)
sysfs_remove_group(kobj, groups[i]);
break;
}
}
return error;
}
/**
* sysfs_create_groups - given a directory kobject, create a bunch of attribute groups
* @kobj: The kobject to create the group on
* @groups: The attribute groups to create, NULL terminated
*
* This function creates a bunch of attribute groups. If an error occurs when
* creating a group, all previously created groups will be removed, unwinding
* everything back to the original state when this function was called.
* It will explicitly warn and error if any of the attribute files being
* created already exist.
*
* Returns 0 on success or error code from sysfs_create_group on failure.
*/
int sysfs_create_groups(struct kobject *kobj,
const struct attribute_group **groups)
{
return internal_create_groups(kobj, 0, groups);
}
EXPORT_SYMBOL_GPL(sysfs_create_groups);
/**
* sysfs_update_groups - given a directory kobject, create a bunch of attribute groups
* @kobj: The kobject to update the group on
* @groups: The attribute groups to update, NULL terminated
*
* This function update a bunch of attribute groups. If an error occurs when
* updating a group, all previously updated groups will be removed together
* with already existing (not updated) attributes.
*
* Returns 0 on success or error code from sysfs_update_group on failure.
*/
int sysfs_update_groups(struct kobject *kobj,
const struct attribute_group **groups)
{
return internal_create_groups(kobj, 1, groups);
}
EXPORT_SYMBOL_GPL(sysfs_update_groups);
/**
* sysfs_update_group - given a directory kobject, update an attribute group
* @kobj: The kobject to update the group on
* @grp: The attribute group to update
*
* This function updates an attribute group. Unlike
* sysfs_create_group(), it will explicitly not warn or error if any
* of the attribute files being created already exist. Furthermore,
* if the visibility of the files has changed through the is_visible()
* callback, it will update the permissions and add or remove the
* relevant files. Changing a group's name (subdirectory name under
* kobj's directory in sysfs) is not allowed.
*
* The primary use for this function is to call it after making a change
* that affects group visibility.
*
* Returns 0 on success or error code on failure.
*/
int sysfs_update_group(struct kobject *kobj,
const struct attribute_group *grp)
{
return internal_create_group(kobj, 1, grp);
}
EXPORT_SYMBOL_GPL(sysfs_update_group);
/**
* sysfs_remove_group: remove a group from a kobject
* @kobj: kobject to remove the group from
* @grp: group to remove
*
* This function removes a group of attributes from a kobject. The attributes
* previously have to have been created for this group, otherwise it will fail.
*/
void sysfs_remove_group(struct kobject *kobj,
const struct attribute_group *grp)
{
struct kernfs_node *parent = kobj->sd;
struct kernfs_node *kn;
if (grp->name) {
kn = kernfs_find_and_get(parent, grp->name);
if (!kn) {
WARN(!kn, KERN_WARNING
"sysfs group '%s' not found for kobject '%s'\n",
grp->name, kobject_name(kobj));
return;
}
} else {
kn = parent;
kernfs_get(kn);
}
remove_files(kn, grp);
if (grp->name)
kernfs_remove(kn);
kernfs_put(kn);
}
EXPORT_SYMBOL_GPL(sysfs_remove_group);
/**
* sysfs_remove_groups - remove a list of groups
*
* @kobj: The kobject for the groups to be removed from
* @groups: NULL terminated list of groups to be removed
*
* If groups is not NULL, remove the specified groups from the kobject.
*/
void sysfs_remove_groups(struct kobject *kobj,
const struct attribute_group **groups)
{
int i;
if (!groups)
return;
for (i = 0; groups[i]; i++)
sysfs_remove_group(kobj, groups[i]);
}
EXPORT_SYMBOL_GPL(sysfs_remove_groups);
/**
* sysfs_merge_group - merge files into a pre-existing attribute group.
* @kobj: The kobject containing the group.
* @grp: The files to create and the attribute group they belong to.
*
* This function returns an error if the group doesn't exist or any of the
* files already exist in that group, in which case none of the new files
* are created.
*/
int sysfs_merge_group(struct kobject *kobj,
const struct attribute_group *grp)
{
struct kernfs_node *parent;
kuid_t uid;
kgid_t gid;
int error = 0;
struct attribute *const *attr;
int i;
parent = kernfs_find_and_get(kobj->sd, grp->name);
if (!parent)
return -ENOENT;
kobject_get_ownership(kobj, &uid, &gid);
for ((i = 0, attr = grp->attrs); *attr && !error; (++i, ++attr))
error = sysfs_add_file_mode_ns(parent, *attr, false,
(*attr)->mode, uid, gid, NULL);
if (error) {
while (--i >= 0)
kernfs_remove_by_name(parent, (*--attr)->name);
}
kernfs_put(parent);
return error;
}
EXPORT_SYMBOL_GPL(sysfs_merge_group);
/**
* sysfs_unmerge_group - remove files from a pre-existing attribute group.
* @kobj: The kobject containing the group.
* @grp: The files to remove and the attribute group they belong to.
*/
void sysfs_unmerge_group(struct kobject *kobj,
const struct attribute_group *grp)
{
struct kernfs_node *parent;
struct attribute *const *attr;
parent = kernfs_find_and_get(kobj->sd, grp->name);
if (parent) {
for (attr = grp->attrs; *attr; ++attr)
kernfs_remove_by_name(parent, (*attr)->name);
kernfs_put(parent);
}
}
EXPORT_SYMBOL_GPL(sysfs_unmerge_group);
/**
* sysfs_add_link_to_group - add a symlink to an attribute group.
* @kobj: The kobject containing the group.
* @group_name: The name of the group.
* @target: The target kobject of the symlink to create.
* @link_name: The name of the symlink to create.
*/
int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
struct kobject *target, const char *link_name)
{
struct kernfs_node *parent;
int error = 0;
parent = kernfs_find_and_get(kobj->sd, group_name);
if (!parent)
return -ENOENT;
error = sysfs_create_link_sd(parent, target, link_name);
kernfs_put(parent);
return error;
}
EXPORT_SYMBOL_GPL(sysfs_add_link_to_group);
/**
* sysfs_remove_link_from_group - remove a symlink from an attribute group.
* @kobj: The kobject containing the group.
* @group_name: The name of the group.
* @link_name: The name of the symlink to remove.
*/
void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
const char *link_name)
{
struct kernfs_node *parent;
parent = kernfs_find_and_get(kobj->sd, group_name);
if (parent) {
kernfs_remove_by_name(parent, link_name);
kernfs_put(parent);
}
}
EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
/**
* __compat_only_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing
* to a group or an attribute
* @kobj: The kobject containing the group.
* @target_kobj: The target kobject.
* @target_name: The name of the target group or attribute.
*/
int __compat_only_sysfs_link_entry_to_kobj(struct kobject *kobj,
struct kobject *target_kobj,
const char *target_name)
{
struct kernfs_node *target;
struct kernfs_node *entry;
struct kernfs_node *link;
/*
* We don't own @target_kobj and it may be removed at any time.
* Synchronize using sysfs_symlink_target_lock. See sysfs_remove_dir()
* for details.
*/
spin_lock(&sysfs_symlink_target_lock);
target = target_kobj->sd;
if (target)
kernfs_get(target);
spin_unlock(&sysfs_symlink_target_lock);
if (!target)
return -ENOENT;
entry = kernfs_find_and_get(target_kobj->sd, target_name);
if (!entry) {
kernfs_put(target);
return -ENOENT;
}
link = kernfs_create_link(kobj->sd, target_name, entry);
if (PTR_ERR(link) == -EEXIST)
sysfs_warn_dup(kobj->sd, target_name);
kernfs_put(entry);
kernfs_put(target);
return PTR_ERR_OR_ZERO(link);
}
EXPORT_SYMBOL_GPL(__compat_only_sysfs_link_entry_to_kobj);
static int sysfs_group_attrs_change_owner(struct kernfs_node *grp_kn,
const struct attribute_group *grp,
struct iattr *newattrs)
{
struct kernfs_node *kn;
int error;
if (grp->attrs) {
struct attribute *const *attr;
for (attr = grp->attrs; *attr; attr++) {
kn = kernfs_find_and_get(grp_kn, (*attr)->name);
if (!kn)
return -ENOENT;
error = kernfs_setattr(kn, newattrs);
kernfs_put(kn);
if (error)
return error;
}
}
if (grp->bin_attrs) {
struct bin_attribute *const *bin_attr;
for (bin_attr = grp->bin_attrs; *bin_attr; bin_attr++) {
kn = kernfs_find_and_get(grp_kn, (*bin_attr)->attr.name);
if (!kn)
return -ENOENT;
error = kernfs_setattr(kn, newattrs);
kernfs_put(kn);
if (error)
return error;
}
}
return 0;
}
/**
* sysfs_group_change_owner - change owner of an attribute group.
* @kobj: The kobject containing the group.
* @grp: The attribute group.
* @kuid: new owner's kuid
* @kgid: new owner's kgid
*
* Returns 0 on success or error code on failure.
*/
int sysfs_group_change_owner(struct kobject *kobj,
const struct attribute_group *grp, kuid_t kuid,
kgid_t kgid)
{
struct kernfs_node *grp_kn;
int error;
struct iattr newattrs = {
.ia_valid = ATTR_UID | ATTR_GID,
.ia_uid = kuid,
.ia_gid = kgid,
};
if (!kobj->state_in_sysfs)
return -EINVAL;
if (grp->name) {
grp_kn = kernfs_find_and_get(kobj->sd, grp->name);
} else {
kernfs_get(kobj->sd);
grp_kn = kobj->sd;
}
if (!grp_kn)
return -ENOENT;
error = kernfs_setattr(grp_kn, &newattrs);
if (!error)
error = sysfs_group_attrs_change_owner(grp_kn, grp, &newattrs);
kernfs_put(grp_kn);
return error;
}
EXPORT_SYMBOL_GPL(sysfs_group_change_owner);
/**
* sysfs_groups_change_owner - change owner of a set of attribute groups.
* @kobj: The kobject containing the groups.
* @groups: The attribute groups.
* @kuid: new owner's kuid
* @kgid: new owner's kgid
*
* Returns 0 on success or error code on failure.
*/
int sysfs_groups_change_owner(struct kobject *kobj,
const struct attribute_group **groups,
kuid_t kuid, kgid_t kgid)
{
int error = 0, i;
if (!kobj->state_in_sysfs)
return -EINVAL;
if (!groups)
return 0;
for (i = 0; groups[i]; i++) {
error = sysfs_group_change_owner(kobj, groups[i], kuid, kgid);
if (error)
break;
}
return error;
}
EXPORT_SYMBOL_GPL(sysfs_groups_change_owner);