linux-kernel - Re: [PATCH 08/16] nfsd: escape high characters in binary data

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Date:   Wed, 10 Jul 2019 18:09:31 -0400
From:   "J. Bruce Fields" <bfields@...ldses.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 08/16] nfsd: escape high characters in binary data

On Fri, Jun 28, 2019 at 12:33:58PM -0400, J. Bruce Fields wrote:
> But I may just give up and go with my existing patch and put
> off that project indefinitely, especially if there's no real need to fix
> the existing callers.

I went with the existing patch, but gave a little more thought to
string_escape_mem.  Stuff that bugs me:

	- ESCAPE_NP sounds like it means "escape nonprinting
	  characters", but actually means "do not escape printing
	  characters"
	- the use of the "only" string to limit the list of escaped
	  characters rather than supplement them is confusing and kind
	  of unhelpful.
	- most of the flags are actually totally unused

So what I'd like to do is:

	- eliminate unused flags
	- use the "only" string to add to, rather than replace, the list
	  of characters to escape
	- separate flags into those that select which characters to
	  escape, and those that choose the format of the escaping ("\ "
	  vs "\x20" vs "\040".)

I've got some patches that do all that and I think it works.  I need to
clean them up a bit and fix up the tests.

--b.