From: Alan Cox <gnomes@lxorguk.ukuu.org.uk>
To: "Serge E. Hallyn" <serge@hallyn.com>
Cc: Peter Dolding <oiaohm@gmail.com>,
Kees Cook <keescook@chromium.org>,
Daniel Micay <danielmicay@gmail.com>, Matt Brown <matt@nmatt.com>,
Greg KH <gregkh@linuxfoundation.org>,
Jiri Slaby <jslaby@suse.com>,
Andrew Morton <akpm@linux-foundation.org>,
Jann Horn <jannh@google.com>, James Morris <jmorris@namei.org>,
"kernel-hardening@lists.openwall.com"
<kernel-hardening@lists.openwall.com>,
linux-security-module <linux-security-module@vger.kernel.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [kernel-hardening] Re: [PATCH v6 0/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN
Date: Tue, 30 May 2017 22:52:45 +0100 [thread overview]
Message-ID: <20170530225245.092497be@alans-desktop> (raw)
In-Reply-To: <20170530155235.GA11861@mail.hallyn.com>
> > So tty stuff should under a tty capabilities.
>
> (last reply on this)
>
> Currently capabilities.7 says
>
> * employ the TIOCSTI ioctl(2) to insert characters into the input queue of a
> terminal other than the caller's controlling terminal;
>
> for CAP_SYS_ADMIN.
>
> So you can create a new CAP_SYS_TIOCSSTI if you like, and offer a patch where
> *both* CAP_SYS_ADMIN and CAP_SYS_ADMIN suffice. Again, see CAP_SYSLOG for a
> prior example.
Even then it wouldn't be useful because the attacker can use every other
interface in the tty layer, many of which you can't magic away behind a
capability bit. And the applications would need changing to use the
feature - at which point any theoretical broken apps can instead be fixed
to use a pty/tty pair and actually fix the real problem.
Alan
WARNING: multiple messages have this Message-ID (diff)
From: gnomes@lxorguk.ukuu.org.uk (Alan Cox)
To: linux-security-module@vger.kernel.org
Subject: [kernel-hardening] Re: [PATCH v6 0/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN
Date: Tue, 30 May 2017 22:52:45 +0100 [thread overview]
Message-ID: <20170530225245.092497be@alans-desktop> (raw)
In-Reply-To: <20170530155235.GA11861@mail.hallyn.com>
> > So tty stuff should under a tty capabilities.
>
> (last reply on this)
>
> Currently capabilities.7 says
>
> * employ the TIOCSTI ioctl(2) to insert characters into the input queue of a
> terminal other than the caller's controlling terminal;
>
> for CAP_SYS_ADMIN.
>
> So you can create a new CAP_SYS_TIOCSSTI if you like, and offer a patch where
> *both* CAP_SYS_ADMIN and CAP_SYS_ADMIN suffice. Again, see CAP_SYSLOG for a
> prior example.
Even then it wouldn't be useful because the attacker can use every other
interface in the tty layer, many of which you can't magic away behind a
capability bit. And the applications would need changing to use the
feature - at which point any theoretical broken apps can instead be fixed
to use a pty/tty pair and actually fix the real problem.
Alan
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next prev parent reply other threads:[~2017-05-30 21:52 UTC|newest]
Thread overview: 77+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-05 23:20 [kernel-hardening] [PATCH v6 0/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN Matt Brown
2017-05-05 23:20 ` Matt Brown
2017-05-05 23:20 ` Matt Brown
2017-05-05 23:20 ` [kernel-hardening] [PATCH v6 1/2] security: tty: Add owner user namespace to tty_struct Matt Brown
2017-05-05 23:20 ` Matt Brown
2017-05-05 23:20 ` Matt Brown
2017-05-05 23:20 ` [kernel-hardening] [PATCH v6 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN Matt Brown
2017-05-05 23:20 ` Matt Brown
2017-05-05 23:20 ` Matt Brown
2017-05-18 13:31 ` [kernel-hardening] " Greg KH
2017-05-18 13:31 ` Greg KH
2017-05-18 13:31 ` Greg KH
2017-05-19 4:51 ` [kernel-hardening] " Matt Brown
2017-05-19 4:51 ` Matt Brown
2017-05-19 4:51 ` Matt Brown
2017-05-10 20:29 ` [kernel-hardening] Re: [PATCH v6 0/2] " Alan Cox
2017-05-10 20:29 ` Alan Cox
2017-05-10 20:29 ` Alan Cox
2017-05-10 21:02 ` [kernel-hardening] " Daniel Micay
2017-05-10 21:02 ` Daniel Micay
2017-05-13 19:52 ` Matt Brown
2017-05-13 19:52 ` Matt Brown
2017-05-13 19:52 ` Matt Brown
2017-05-15 4:45 ` [kernel-hardening] " Nicolas Belouin
2017-05-15 20:57 ` Alan Cox
2017-05-15 20:57 ` Alan Cox
2017-05-15 20:57 ` Alan Cox
2017-05-15 23:10 ` [kernel-hardening] " Peter Dolding
2017-05-15 23:10 ` Peter Dolding
2017-05-15 23:10 ` Peter Dolding
2017-05-16 4:15 ` [kernel-hardening] " Matt Brown
2017-05-16 4:15 ` Matt Brown
2017-05-16 4:15 ` Matt Brown
2017-05-16 9:01 ` [kernel-hardening] " Peter Dolding
2017-05-16 9:01 ` Peter Dolding
2017-05-16 9:01 ` Peter Dolding
2017-05-16 12:22 ` [kernel-hardening] " Matt Brown
2017-05-16 12:22 ` Matt Brown
2017-05-16 12:22 ` Matt Brown
2017-05-16 14:28 ` [kernel-hardening] " Kees Cook
2017-05-16 14:28 ` Kees Cook
2017-05-16 14:28 ` Kees Cook
2017-05-16 15:48 ` [kernel-hardening] " Serge E. Hallyn
2017-05-16 15:48 ` Serge E. Hallyn
2017-05-16 22:05 ` Peter Dolding
2017-05-16 22:05 ` Peter Dolding
2017-05-16 21:43 ` Peter Dolding
2017-05-16 21:43 ` Peter Dolding
2017-05-16 21:43 ` Peter Dolding
2017-05-16 21:54 ` [kernel-hardening] " Matt Brown
2017-05-16 21:54 ` Matt Brown
2017-05-16 21:54 ` Matt Brown
2017-05-17 16:41 ` [kernel-hardening] " Alan Cox
2017-05-17 16:41 ` Alan Cox
2017-05-17 16:41 ` Alan Cox
2017-05-17 18:25 ` [kernel-hardening] " Daniel Micay
2017-05-17 18:25 ` Daniel Micay
2017-05-17 23:04 ` Boris Lukashev
2017-05-18 3:18 ` Kees Cook
2017-05-18 3:18 ` Kees Cook
2017-05-19 2:48 ` Peter Dolding
2017-05-19 2:48 ` Peter Dolding
2017-05-19 4:08 ` Boris Lukashev
2017-05-19 14:33 ` Serge E. Hallyn
2017-05-19 14:33 ` Serge E. Hallyn
2017-05-29 10:42 ` Peter Dolding
2017-05-29 10:42 ` Peter Dolding
2017-05-30 15:52 ` Serge E. Hallyn
2017-05-30 15:52 ` Serge E. Hallyn
2017-05-30 21:52 ` Alan Cox [this message]
2017-05-30 21:52 ` Alan Cox
2017-05-31 11:27 ` Peter Dolding
2017-05-31 11:27 ` Peter Dolding
2017-05-31 14:36 ` Alan Cox
2017-05-31 14:36 ` Alan Cox
2017-05-31 15:32 ` Serge E. Hallyn
2017-05-31 15:32 ` Serge E. Hallyn
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