Commit d0ae3d43 authored Dec 11, 2013 by Tejun Heo Committed by Greg Kroah-Hartman Dec 17, 2013

kernfs: add REMOVED check to create and rename paths



kernfs currently assumes that the caller doesn't try to create a new
node under a removed parent, rename a removed node, or move a node
under a removed node.  While this works fine for sysfs, it'd be nice
to have protection against such cases especially given that kernfs is
planned to add support for mkdir, rmdir and rename requsts from
userland which may make race conditions more likely.

This patch updates create and rename paths to check REMOVED and fail
the operation with -ENOENT if performed on or towards removed nodes.
Note that remove path already has such check.

Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent bb8b9d09

fs/kernfs/dir.c

+7 −0

Original line number	Diff line number	Diff line
		@@ -430,6 +430,9 @@ int kernfs_add_one(struct kernfs_addrm_cxt acxt, struct kernfs_node kn,
		if (kernfs_type(parent) != KERNFS_DIR)
		return -EINVAL;

		if (parent->flags & KERNFS_REMOVED)
		return -ENOENT;

		kn->hash = kernfs_name_hash(kn->name, kn->ns);
		kn->parent = parent;
		kernfs_get(parent);
		@@ -863,6 +866,10 @@ int kernfs_rename_ns(struct kernfs_node kn, struct kernfs_node new_parent,

		mutex_lock(&kernfs_mutex);

		error = -ENOENT;
		if ((kn->flags \| new_parent->flags) & KERNFS_REMOVED)
		goto out;

		error = 0;
		if ((kn->parent == new_parent) && (kn->ns == new_ns) &&
		(strcmp(kn->name, new_name) == 0))

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