Commit f70ce185 authored by Christian Brauner's avatar Christian Brauner Committed by David S. Miller
Browse files

sysfs: add sysfs_file_change_owner() 



Add helpers to change the owner of a sysfs files.
This function will be used to correctly account for kobject ownership
changes, e.g. when moving network devices between network namespaces.

Reviewed-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarChristian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent d1c73cbd

fs/sysfs/file.c

+47 −0
Original line number Diff line number Diff line
@@ -558,3 +558,50 @@ void sysfs_remove_bin_file(struct kobject *kobj, 
	kernfs_remove_by_name(kobj->sd, attr->attr.name);

}

EXPORT_SYMBOL_GPL(sysfs_remove_bin_file);



static int internal_change_owner(struct kernfs_node *kn, kuid_t kuid,

				 kgid_t kgid)

{

	struct iattr newattrs = {

		.ia_valid = ATTR_UID | ATTR_GID,

		.ia_uid = kuid,

		.ia_gid = kgid,

	};

	return kernfs_setattr(kn, &newattrs);

}



/**

 *	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)

{

	struct kernfs_node *kn;

	int error;



	if (!name)

		return -EINVAL;



	if (!kobj->state_in_sysfs)

		return -EINVAL;



	kn = kernfs_find_and_get(kobj->sd, name);

	if (!kn)

		return -ENOENT;



	error = internal_change_owner(kn, kuid, kgid);



	kernfs_put(kn);



	return error;

}

EXPORT_SYMBOL_GPL(sysfs_file_change_owner);

include/linux/sysfs.h

+10 −0
Original line number Diff line number Diff line
@@ -310,6 +310,9 @@ static inline void sysfs_enable_ns(struct kernfs_node *kn) 
	return kernfs_enable_ns(kn);

}



int sysfs_file_change_owner(struct kobject *kobj, const char *name, kuid_t kuid,

			    kgid_t kgid);



#else /* CONFIG_SYSFS */



static inline int sysfs_create_dir_ns(struct kobject *kobj, const void *ns)
@@ -522,6 +525,13 @@ static inline void sysfs_enable_ns(struct kernfs_node *kn) 
{

}



static inline int sysfs_file_change_owner(struct kobject *kobj,

					  const char *name, kuid_t kuid,

					  kgid_t kgid)

{

	return 0;

}



#endif /* CONFIG_SYSFS */



static inline int __must_check sysfs_create_file(struct kobject *kobj,