Commit 0666a3ae authored by Christian Brauner's avatar Christian Brauner Committed by David S. Miller
Browse files

sysfs: add sysfs_link_change_owner() 



Add a helper to change the owner of a sysfs link.
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 f70ce185

fs/sysfs/file.c

+41 −0
Original line number Diff line number Diff line
@@ -570,6 +570,47 @@ static int internal_change_owner(struct kernfs_node *kn, kuid_t kuid, 
	return kernfs_setattr(kn, &newattrs);

}



/**

 *	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)

{

	struct kernfs_node *kn = NULL;

	int error;



	if (!name || !kobj->state_in_sysfs || !targ->state_in_sysfs)

		return -EINVAL;



	error = -ENOENT;

	kn = kernfs_find_and_get_ns(kobj->sd, name, targ->sd->ns);

	if (!kn)

		goto out;



	error = -EINVAL;

	if (kernfs_type(kn) != KERNFS_LINK)

		goto out;

	if (kn->symlink.target_kn->priv != targ)

		goto out;



	error = internal_change_owner(kn, kuid, kgid);



out:

	kernfs_put(kn);

	return error;

}



/**

 *	sysfs_file_change_owner - change owner of a sysfs file.

 *	@kobj:	object.

include/linux/sysfs.h

+10 −0
Original line number Diff line number Diff line
@@ -312,6 +312,8 @@ static inline void sysfs_enable_ns(struct kernfs_node *kn) 


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

			    kgid_t kgid);

int sysfs_link_change_owner(struct kobject *kobj, struct kobject *targ,

			    const char *name, kuid_t kuid, kgid_t kgid);



#else /* CONFIG_SYSFS */
@@ -532,6 +534,14 @@ static inline int sysfs_file_change_owner(struct kobject *kobj, 
	return 0;

}



static inline int sysfs_link_change_owner(struct kobject *kobj,

					  struct kobject *targ,

					  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,

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