From: Pavel Machek <pavel@ucw.cz>
To: Greg KH <gregkh@suse.de>
Cc: Vasiliy Kulikov <segoon@openwall.com>,
Andrew Morton <akpm@linux-foundation.org>,
James Morris <jmorris@namei.org>, Ingo Molnar <mingo@elte.hu>,
Namhyung Kim <namhyung@gmail.com>,
kernel-hardening@lists.openwall.com,
linux-kernel@vger.kernel.org, security@kernel.org
Subject: [kernel-hardening] Re: [PATCH] kernel: escape non-ASCII and control characters in printk()
Date: Mon, 11 Jul 2011 06:37:20 +0000 [thread overview]
Message-ID: <20110711063719.GA12579@localhost.ucw.cz> (raw)
In-Reply-To: <20110622153742.GA18983@suse.de>
On Wed 2011-06-22 08:37:42, Greg KH wrote:
> On Wed, Jun 22, 2011 at 01:53:41PM +0400, Vasiliy Kulikov wrote:
> > This patch escapes all characters outside of allowed '\n' plus 0x20-0x7E
> > charset passed to printk().
> >
> > There are numerous printk() instances with user supplied input as "%s"
> > data, and unprivileged user may craft log messages with substrings
> > containing control characters via these printk()s. Control characters
> > might fool root viewing the logs via tty.
>
> There are "numerous" places this could happen? Shouldn't this be
> handled by the viewers of the log file and not the kernel itself?
well, currently cat /proc/kmsg is bad idea on multiuser system... right?
> And what could these control characters cause to be "fooled"?
terminals are powerful (or shall we say insecure?) these days. Including replies.
cat /proc/kmsg can result in something like "9q" be added to the next
bash command. It would not surprise me if nastier stuff was possible
with some xterm variant.
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
WARNING: multiple messages have this Message-ID (diff)
From: Pavel Machek <pavel@ucw.cz>
To: Greg KH <gregkh@suse.de>
Cc: Vasiliy Kulikov <segoon@openwall.com>,
Andrew Morton <akpm@linux-foundation.org>,
James Morris <jmorris@namei.org>, Ingo Molnar <mingo@elte.hu>,
Namhyung Kim <namhyung@gmail.com>,
kernel-hardening@lists.openwall.com,
linux-kernel@vger.kernel.org, security@kernel.org
Subject: Re: [PATCH] kernel: escape non-ASCII and control characters in printk()
Date: Mon, 11 Jul 2011 06:37:20 +0000 [thread overview]
Message-ID: <20110711063719.GA12579@localhost.ucw.cz> (raw)
In-Reply-To: <20110622153742.GA18983@suse.de>
On Wed 2011-06-22 08:37:42, Greg KH wrote:
> On Wed, Jun 22, 2011 at 01:53:41PM +0400, Vasiliy Kulikov wrote:
> > This patch escapes all characters outside of allowed '\n' plus 0x20-0x7E
> > charset passed to printk().
> >
> > There are numerous printk() instances with user supplied input as "%s"
> > data, and unprivileged user may craft log messages with substrings
> > containing control characters via these printk()s. Control characters
> > might fool root viewing the logs via tty.
>
> There are "numerous" places this could happen? Shouldn't this be
> handled by the viewers of the log file and not the kernel itself?
well, currently cat /proc/kmsg is bad idea on multiuser system... right?
> And what could these control characters cause to be "fooled"?
terminals are powerful (or shall we say insecure?) these days. Including replies.
cat /proc/kmsg can result in something like "9q" be added to the next
bash command. It would not surprise me if nastier stuff was possible
with some xterm variant.
--
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
next prev parent reply other threads:[~2011-07-11 6:37 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-22 9:53 [kernel-hardening] [PATCH] kernel: escape non-ASCII and control characters in printk() Vasiliy Kulikov
2011-06-22 9:53 ` Vasiliy Kulikov
2011-06-22 15:37 ` [kernel-hardening] " Greg KH
2011-06-22 15:37 ` Greg KH
2011-06-22 16:13 ` [kernel-hardening] " Vasiliy Kulikov
2011-06-22 16:13 ` Vasiliy Kulikov
2011-06-23 13:36 ` [kernel-hardening] " Matthew Garrett
2011-06-23 13:36 ` Matthew Garrett
2011-06-23 21:44 ` [kernel-hardening] " Greg KH
2011-06-23 21:44 ` Greg KH
2011-07-11 6:37 ` Pavel Machek [this message]
2011-07-11 6:37 ` Pavel Machek
2011-06-22 16:38 ` [kernel-hardening] " Joe Perches
2011-06-22 16:38 ` Joe Perches
2011-06-22 16:53 ` [kernel-hardening] " Vasiliy Kulikov
2011-06-22 16:53 ` Vasiliy Kulikov
2011-06-22 17:14 ` [kernel-hardening] " Joe Perches
2011-06-22 17:14 ` Joe Perches
2011-06-22 17:48 ` [kernel-hardening] " Vasiliy Kulikov
2011-06-22 17:48 ` Vasiliy Kulikov
2011-06-22 18:10 ` [kernel-hardening] " Alan Cox
2011-06-22 18:10 ` Alan Cox
2011-06-22 19:07 ` [kernel-hardening] " Vasiliy Kulikov
2011-06-22 19:07 ` Vasiliy Kulikov
2011-06-23 18:11 ` [kernel-hardening] " Geert Uytterhoeven
2011-06-23 18:11 ` Geert Uytterhoeven
2011-06-25 20:52 ` [kernel-hardening] Re: [Security] " Willy Tarreau
2011-06-25 20:52 ` Willy Tarreau
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