afs: Hide silly-rename files from userspace

[ Upstream commit 57e9d49c54 ]

There appears to be a race between silly-rename files being created/removed
and various userspace tools iterating over the contents of a directory,
leading to such errors as:

	find: './kernel/.tmp_cpio_dir/include/dt-bindings/reset/.__afs2080': No such file or directory
	tar: ./include/linux/greybus/.__afs3C95: File removed before we read it

when building a kernel.

Fix afs_readdir() so that it doesn't return .__afsXXXX silly-rename files
to userspace.  This doesn't stop them being looked up directly by name as
we need to be able to look them up from within the kernel as part of the
silly-rename algorithm.

Fixes: 79ddbfa500 ("afs: Implement sillyrename for unlink and rename")
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
David Howells 2024-01-08 17:22:36 +00:00 committed by Greg Kroah-Hartman
parent a1eebe76e1
commit a53411e805

View file

@ -474,6 +474,14 @@ static int afs_dir_iterate_block(struct afs_vnode *dvnode,
continue;
}
/* Don't expose silly rename entries to userspace. */
if (nlen > 6 &&
dire->u.name[0] == '.' &&
ctx->actor != afs_lookup_filldir &&
ctx->actor != afs_lookup_one_filldir &&
memcmp(dire->u.name, ".__afs", 6) == 0)
continue;
/* found the next entry */
if (!dir_emit(ctx, dire->u.name, nlen,
ntohl(dire->u.vnode),