@@ -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.
@@ -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,
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. Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> --- /* v2 */ - Greg Kroah-Hartman <gregkh@linuxfoundation.org>: - Add comment how ownership of sysfs object is changed. /* v3 */ - Greg Kroah-Hartman <gregkh@linuxfoundation.org>: - Add explicit uid/gid parameters. /* v4 */ - Christian Brauner <christian.brauner@ubuntu.com>: - Add more documentation. --- fs/sysfs/file.c | 41 +++++++++++++++++++++++++++++++++++++++++ include/linux/sysfs.h | 10 ++++++++++ 2 files changed, 51 insertions(+)