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authorChristian Brauner <christian.brauner@ubuntu.com>2020-02-27 04:37:12 +0100
committerDavid S. Miller <davem@davemloft.net>2020-02-26 20:07:25 -0800
commit0666a3aee762cd4f7981c2eed0fd8cab87533539 (patch)
tree777513bd25867a6d981901eb0987fb90fcdd68ee /fs/sysfs
parentf70ce185687bbe4e2d7ff126a8c890631f5fc2af (diff)
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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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'fs/sysfs')
-rw-r--r--fs/sysfs/file.c41
1 files changed, 41 insertions, 0 deletions
diff --git a/fs/sysfs/file.c b/fs/sysfs/file.c
index 4ca936ca3ba4..332cd69b378c 100644
--- a/fs/sysfs/file.c
+++ b/fs/sysfs/file.c
@@ -571,6 +571,47 @@ static int internal_change_owner(struct kernfs_node *kn, kuid_t kuid,
}
/**
+ * 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.
* @name: name of the file to change.