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Normally kobjects and their sysfs representation belong to global root, however it is not necessarily the case for objects in separate namespaces. For example, objects in separate network namespace logically belong to the container's root and not global root. This change lays groundwork for allowing network namespace objects ownership to be transferred to container's root user by defining get_ownership() callback in ktype structure and using it in sysfs code to retrieve desired uid/gid when creating sysfs objects for given kobject. Co-Developed-by: Tyler Hicks <tyhicks@canonical.com> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com> Signed-off-by: Tyler Hicks <tyhicks@canonical.com> Signed-off-by: David S. Miller <davem@davemloft.net>
162 lines
4.1 KiB
C
162 lines
4.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fs/sysfs/dir.c - sysfs core and dir operation implementation
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*
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* Copyright (c) 2001-3 Patrick Mochel
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* Copyright (c) 2007 SUSE Linux Products GmbH
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* Copyright (c) 2007 Tejun Heo <teheo@suse.de>
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*
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* Please see Documentation/filesystems/sysfs.txt for more information.
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*/
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#define pr_fmt(fmt) "sysfs: " fmt
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#include <linux/fs.h>
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#include <linux/kobject.h>
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#include <linux/slab.h>
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#include "sysfs.h"
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DEFINE_SPINLOCK(sysfs_symlink_target_lock);
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void sysfs_warn_dup(struct kernfs_node *parent, const char *name)
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{
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char *buf;
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buf = kzalloc(PATH_MAX, GFP_KERNEL);
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if (buf)
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kernfs_path(parent, buf, PATH_MAX);
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pr_warn("cannot create duplicate filename '%s/%s'\n", buf, name);
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dump_stack();
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kfree(buf);
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}
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/**
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* sysfs_create_dir_ns - create a directory for an object with a namespace tag
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* @kobj: object we're creating directory for
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* @ns: the namespace tag to use
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*/
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int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
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{
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struct kernfs_node *parent, *kn;
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kuid_t uid;
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kgid_t gid;
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BUG_ON(!kobj);
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if (kobj->parent)
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parent = kobj->parent->sd;
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else
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parent = sysfs_root_kn;
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if (!parent)
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return -ENOENT;
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kobject_get_ownership(kobj, &uid, &gid);
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kn = kernfs_create_dir_ns(parent, kobject_name(kobj),
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S_IRWXU | S_IRUGO | S_IXUGO, uid, gid,
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kobj, ns);
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if (IS_ERR(kn)) {
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if (PTR_ERR(kn) == -EEXIST)
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sysfs_warn_dup(parent, kobject_name(kobj));
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return PTR_ERR(kn);
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}
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kobj->sd = kn;
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return 0;
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}
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/**
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* sysfs_remove_dir - remove an object's directory.
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* @kobj: object.
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*
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* The only thing special about this is that we remove any files in
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* the directory before we remove the directory, and we've inlined
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* what used to be sysfs_rmdir() below, instead of calling separately.
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*/
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void sysfs_remove_dir(struct kobject *kobj)
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{
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struct kernfs_node *kn = kobj->sd;
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/*
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* In general, kboject owner is responsible for ensuring removal
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* doesn't race with other operations and sysfs doesn't provide any
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* protection; however, when @kobj is used as a symlink target, the
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* symlinking entity usually doesn't own @kobj and thus has no
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* control over removal. @kobj->sd may be removed anytime
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* and symlink code may end up dereferencing an already freed node.
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*
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* sysfs_symlink_target_lock synchronizes @kobj->sd
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* disassociation against symlink operations so that symlink code
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* can safely dereference @kobj->sd.
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*/
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spin_lock(&sysfs_symlink_target_lock);
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kobj->sd = NULL;
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spin_unlock(&sysfs_symlink_target_lock);
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if (kn) {
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WARN_ON_ONCE(kernfs_type(kn) != KERNFS_DIR);
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kernfs_remove(kn);
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}
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}
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int sysfs_rename_dir_ns(struct kobject *kobj, const char *new_name,
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const void *new_ns)
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{
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struct kernfs_node *parent;
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int ret;
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parent = kernfs_get_parent(kobj->sd);
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ret = kernfs_rename_ns(kobj->sd, parent, new_name, new_ns);
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kernfs_put(parent);
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return ret;
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}
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int sysfs_move_dir_ns(struct kobject *kobj, struct kobject *new_parent_kobj,
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const void *new_ns)
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{
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struct kernfs_node *kn = kobj->sd;
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struct kernfs_node *new_parent;
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new_parent = new_parent_kobj && new_parent_kobj->sd ?
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new_parent_kobj->sd : sysfs_root_kn;
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return kernfs_rename_ns(kn, new_parent, kn->name, new_ns);
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}
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/**
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* sysfs_create_mount_point - create an always empty directory
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* @parent_kobj: kobject that will contain this always empty directory
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* @name: The name of the always empty directory to add
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*/
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int sysfs_create_mount_point(struct kobject *parent_kobj, const char *name)
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{
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struct kernfs_node *kn, *parent = parent_kobj->sd;
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kn = kernfs_create_empty_dir(parent, name);
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if (IS_ERR(kn)) {
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if (PTR_ERR(kn) == -EEXIST)
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sysfs_warn_dup(parent, name);
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return PTR_ERR(kn);
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}
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return 0;
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}
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EXPORT_SYMBOL_GPL(sysfs_create_mount_point);
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/**
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* sysfs_remove_mount_point - remove an always empty directory.
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* @parent_kobj: kobject that will contain this always empty directory
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* @name: The name of the always empty directory to remove
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*
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*/
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void sysfs_remove_mount_point(struct kobject *parent_kobj, const char *name)
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{
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struct kernfs_node *parent = parent_kobj->sd;
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kernfs_remove_by_name_ns(parent, name, NULL);
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}
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EXPORT_SYMBOL_GPL(sysfs_remove_mount_point);
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