linux-kernel - Re: [PATCH v2] kernel: escape non-ASCII and control characters in printk()

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Message-ID: <CA+55aFwWkfYQbdgxYg3Wo-9o1XqPQcOPt9=u1E0zeMzZe30R9w@mail.gmail.com>
Date:	Sun, 3 Jul 2011 14:34:39 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
Cc:	Vasiliy Kulikov <segoon@...nwall.com>, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	James Morris <jmorris@...ei.org>,
	Namhyung Kim <namhyung@...il.com>,
	Greg Kroah-Hartman <gregkh@...e.de>,
	kernel-hardening@...ts.openwall.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] kernel: escape non-ASCII and control characters in printk()

On Sun, Jul 3, 2011 at 2:10 PM, Alan Cox <alan@...rguk.ukuu.org.uk> wrote:
>
> In which case we can't do it because we need \n in proc content so that's
> a complete and utter non starter.

You didn't read the original email I sent, did you?

For people who _want_ the unsafe versions with \n and other control
characters, they'd use a "raw string" format. Something like our
extended "%p" formats. Maybe '%p[]' - we could allow extensions later
that describe which characters to escape inside the brackets (for
example, we currently have ad-hoc escaping of things like pathnames:
with '/' not being legal in a path component)

The point being that that way it would be (a) safe by default (b)
require _thought_ when you actually wanted to print control characters
and (c) be easily greppable too.

                           Linus
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