From: "Serge E. Hallyn" <serge@hallyn.com>
To: Matt Brown <matt@nmatt.com>
Cc: "Serge E. Hallyn" <serge@hallyn.com>,
Alan Cox <gnomes@lxorguk.ukuu.org.uk>,
Kees Cook <keescook@chromium.org>,
Casey Schaufler <casey@schaufler-ca.com>,
Boris Lukashev <blukashev@sempervictus.com>,
Greg KH <gregkh@linuxfoundation.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>,
linux-api@vger.kernel.org
Subject: Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN
Date: Fri, 2 Jun 2017 13:18:22 -0500 [thread overview]
Message-ID: <20170602181822.GA5125@mail.hallyn.com> (raw)
In-Reply-To: <3027e4fa-5dc2-a52f-8699-9974cb4d4b6b@nmatt.com>
Quoting Matt Brown (matt@nmatt.com):
> On 6/2/17 12:57 PM, Serge E. Hallyn wrote:
> > I'm not quite sure what you're asking for here. Let me offer a precise
> > strawman design. I'm sure there are problems with it, it's just a starting
> > point.
> >
> > system-wide whitelist (for now 'may_push_chars') is full by default.
> >
>
> So is may_push_chars just an alias for TIOCSTI? Or are there some
> potential whitelist members that would map to multiple ioctls?
<shrug> I'm seeing it as only TIOCSTI right now.
> > By default, nothing changes - you can use those on your own tty, need
> > CAP_SYS_ADMIN against init_user_ns otherwise.
> >
> > Introduce a new CAP_TTY_PRIVILEGED.
> >
>
> I'm fine with this.
>
> > When may_push_chars is removed from the whitelist, you lose the ability
> > to use TIOCSTI on a tty - even your own - if you do not have CAP_TTY_PRIVILEGED
> > against the tty's user_ns.
> >
>
> How do you propose storing/updating the whitelist? sysctl?
>
> If it is a sysctl, would each whitelist member have a sysctl?
> e.g.: kernel.ioctlwhitelist.may_push_chars = 1
>
> Overall, I'm fine with this idea.
That sounds reasonable. Or a securityfs file - I guess not everyone
has securityfs, but if it were to become part of YAMA then that would
work.
-serge
WARNING: multiple messages have this Message-ID (diff)
From: "Serge E. Hallyn" <serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>
To: Matt Brown <matt-YiBOUZGZpYMAvxtiuMwx3w@public.gmane.org>
Cc: "Serge E. Hallyn" <serge-A9i7LUbDfNHQT0dZR+AlfA@public.gmane.org>,
Alan Cox
<gnomes-qBU/x9rampVanCEyBjwyrvXRex20P6io@public.gmane.org>,
Kees Cook <keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
Casey Schaufler <casey-iSGtlc1asvQWG2LlvL+J4A@public.gmane.org>,
Boris Lukashev
<blukashev-JNja4Z15B3SvB/ACxS1yDA@public.gmane.org>,
Greg KH
<gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
"kernel-hardening-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8@public.gmane.org"
<kernel-hardening-ZwoEplunGu1jrUoiu81ncdBPR1lH4CV8@public.gmane.org>,
linux-security-module
<linux-security-module-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-kernel
<linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
Subject: Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN
Date: Fri, 2 Jun 2017 13:18:22 -0500 [thread overview]
Message-ID: <20170602181822.GA5125@mail.hallyn.com> (raw)
In-Reply-To: <3027e4fa-5dc2-a52f-8699-9974cb4d4b6b-YiBOUZGZpYMAvxtiuMwx3w@public.gmane.org>
Quoting Matt Brown (matt-YiBOUZGZpYMAvxtiuMwx3w@public.gmane.org):
> On 6/2/17 12:57 PM, Serge E. Hallyn wrote:
> > I'm not quite sure what you're asking for here. Let me offer a precise
> > strawman design. I'm sure there are problems with it, it's just a starting
> > point.
> >
> > system-wide whitelist (for now 'may_push_chars') is full by default.
> >
>
> So is may_push_chars just an alias for TIOCSTI? Or are there some
> potential whitelist members that would map to multiple ioctls?
<shrug> I'm seeing it as only TIOCSTI right now.
> > By default, nothing changes - you can use those on your own tty, need
> > CAP_SYS_ADMIN against init_user_ns otherwise.
> >
> > Introduce a new CAP_TTY_PRIVILEGED.
> >
>
> I'm fine with this.
>
> > When may_push_chars is removed from the whitelist, you lose the ability
> > to use TIOCSTI on a tty - even your own - if you do not have CAP_TTY_PRIVILEGED
> > against the tty's user_ns.
> >
>
> How do you propose storing/updating the whitelist? sysctl?
>
> If it is a sysctl, would each whitelist member have a sysctl?
> e.g.: kernel.ioctlwhitelist.may_push_chars = 1
>
> Overall, I'm fine with this idea.
That sounds reasonable. Or a securityfs file - I guess not everyone
has securityfs, but if it were to become part of YAMA then that would
work.
-serge
WARNING: multiple messages have this Message-ID (diff)
From: serge@hallyn.com (Serge E. Hallyn)
To: linux-security-module@vger.kernel.org
Subject: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN
Date: Fri, 2 Jun 2017 13:18:22 -0500 [thread overview]
Message-ID: <20170602181822.GA5125@mail.hallyn.com> (raw)
In-Reply-To: <3027e4fa-5dc2-a52f-8699-9974cb4d4b6b@nmatt.com>
Quoting Matt Brown (matt at nmatt.com):
> On 6/2/17 12:57 PM, Serge E. Hallyn wrote:
> > I'm not quite sure what you're asking for here. Let me offer a precise
> > strawman design. I'm sure there are problems with it, it's just a starting
> > point.
> >
> > system-wide whitelist (for now 'may_push_chars') is full by default.
> >
>
> So is may_push_chars just an alias for TIOCSTI? Or are there some
> potential whitelist members that would map to multiple ioctls?
<shrug> I'm seeing it as only TIOCSTI right now.
> > By default, nothing changes - you can use those on your own tty, need
> > CAP_SYS_ADMIN against init_user_ns otherwise.
> >
> > Introduce a new CAP_TTY_PRIVILEGED.
> >
>
> I'm fine with this.
>
> > When may_push_chars is removed from the whitelist, you lose the ability
> > to use TIOCSTI on a tty - even your own - if you do not have CAP_TTY_PRIVILEGED
> > against the tty's user_ns.
> >
>
> How do you propose storing/updating the whitelist? sysctl?
>
> If it is a sysctl, would each whitelist member have a sysctl?
> e.g.: kernel.ioctlwhitelist.may_push_chars = 1
>
> Overall, I'm fine with this idea.
That sounds reasonable. Or a securityfs file - I guess not everyone
has securityfs, but if it were to become part of YAMA then that would
work.
-serge
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next prev parent reply other threads:[~2017-06-02 18:18 UTC|newest]
Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-29 21:37 [PATCH v7 0/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN Matt Brown
2017-05-29 21:37 ` [kernel-hardening] " Matt Brown
2017-05-29 21:37 ` Matt Brown
2017-05-29 21:37 ` [PATCH v7 1/2] security: tty: Add owner user namespace to tty_struct Matt Brown
2017-05-29 21:37 ` [kernel-hardening] " Matt Brown
2017-05-29 21:37 ` Matt Brown
2017-05-29 21:38 ` [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN Matt Brown
2017-05-29 21:38 ` [kernel-hardening] " Matt Brown
2017-05-29 21:38 ` Matt Brown
2017-05-29 22:26 ` Alan Cox
2017-05-29 22:26 ` [kernel-hardening] " Alan Cox
2017-05-29 22:26 ` Alan Cox
2017-05-29 23:51 ` [kernel-hardening] " Boris Lukashev
2017-05-29 23:51 ` Boris Lukashev
2017-05-30 0:27 ` Casey Schaufler
2017-05-30 0:27 ` Casey Schaufler
2017-05-30 2:00 ` Matt Brown
2017-05-30 2:00 ` Matt Brown
2017-05-30 2:46 ` Casey Schaufler
2017-05-30 2:46 ` Casey Schaufler
2017-05-30 3:18 ` Matt Brown
2017-05-30 3:18 ` Matt Brown
2017-05-30 12:24 ` Alan Cox
2017-05-30 12:24 ` Alan Cox
2017-05-30 16:28 ` Matt Brown
2017-05-30 16:28 ` Matt Brown
2017-05-30 16:44 ` Daniel Micay
2017-05-30 16:44 ` Daniel Micay
2017-05-30 18:32 ` Stephen Smalley
2017-05-30 18:32 ` Stephen Smalley
2017-05-30 18:44 ` Nick Kralevich
2017-05-30 18:44 ` Nick Kralevich
2017-05-30 18:57 ` Matt Brown
2017-05-30 18:57 ` Matt Brown
2017-05-30 20:22 ` Daniel Micay
2017-05-30 20:22 ` Daniel Micay
2017-05-30 23:00 ` Matt Brown
2017-05-30 23:00 ` Matt Brown
2017-05-30 23:40 ` Daniel Micay
2017-05-30 23:40 ` Daniel Micay
2017-05-30 23:59 ` Matt Brown
2017-05-30 23:59 ` Matt Brown
2017-05-30 22:51 ` Alan Cox
2017-05-30 22:51 ` Alan Cox
2017-05-30 23:19 ` Matt Brown
2017-05-30 23:19 ` Matt Brown
2017-05-30 23:56 ` Alan Cox
2017-05-30 23:56 ` Alan Cox
2017-06-01 2:35 ` Kees Cook
2017-06-01 2:35 ` Kees Cook
2017-06-01 2:35 ` Kees Cook
2017-06-01 7:12 ` lazytyped
2017-06-01 18:46 ` Kees Cook
2017-06-01 22:56 ` James Morris
2017-06-02 18:46 ` Kees Cook
2017-06-01 13:08 ` Alan Cox
2017-06-01 13:08 ` Alan Cox
2017-06-01 13:08 ` Alan Cox
2017-06-01 17:18 ` Serge E. Hallyn
2017-06-01 17:18 ` Serge E. Hallyn
2017-06-01 17:18 ` Serge E. Hallyn
2017-06-01 21:26 ` Alan Cox
2017-06-01 21:26 ` Alan Cox
2017-06-01 21:26 ` Alan Cox
2017-06-01 18:58 ` Kees Cook
2017-06-01 18:58 ` Kees Cook
2017-06-01 18:58 ` Kees Cook
2017-06-01 21:24 ` Alan Cox
2017-06-01 21:24 ` Alan Cox
2017-06-01 21:24 ` Alan Cox
2017-06-02 14:46 ` Matt Brown
2017-06-02 14:46 ` Matt Brown
2017-06-02 14:46 ` Matt Brown
2017-06-02 15:36 ` Serge E. Hallyn
2017-06-02 15:36 ` Serge E. Hallyn
2017-06-02 15:36 ` Serge E. Hallyn
2017-06-02 16:02 ` Matt Brown
2017-06-02 16:02 ` Matt Brown
2017-06-02 16:02 ` Matt Brown
2017-06-02 16:57 ` Serge E. Hallyn
2017-06-02 16:57 ` Serge E. Hallyn
2017-06-02 16:57 ` Serge E. Hallyn
2017-06-02 16:57 ` Serge E. Hallyn
2017-06-02 17:32 ` Matt Brown
2017-06-02 17:32 ` Matt Brown
2017-06-02 17:32 ` Matt Brown
2017-06-02 18:18 ` Serge E. Hallyn [this message]
2017-06-02 18:18 ` Serge E. Hallyn
2017-06-02 18:18 ` Serge E. Hallyn
2017-06-02 18:18 ` Serge E. Hallyn
2017-06-02 19:22 ` Matt Brown
2017-06-02 19:22 ` Matt Brown
2017-06-02 19:22 ` Matt Brown
2017-06-02 19:25 ` Kees Cook
2017-06-02 19:25 ` Kees Cook
2017-06-02 19:25 ` Kees Cook
2017-06-02 19:25 ` Kees Cook
2017-06-02 19:26 ` Matt Brown
2017-06-02 19:26 ` Matt Brown
2017-06-02 19:26 ` Matt Brown
2017-06-02 19:26 ` Matt Brown
2017-06-02 20:05 ` Alan Cox
2017-06-02 20:05 ` Alan Cox
2017-06-02 20:05 ` Alan Cox
2017-06-02 20:11 ` Nick Kralevich
2017-06-02 20:11 ` Nick Kralevich
2017-06-02 20:11 ` Nick Kralevich
2017-06-02 20:46 ` Matt Brown
2017-06-02 20:46 ` Matt Brown
2017-06-02 20:46 ` Matt Brown
2017-06-03 22:00 ` Alan Cox
2017-06-03 22:00 ` Alan Cox
2017-06-03 22:00 ` Alan Cox
2017-06-03 22:22 ` Matt Brown
2017-06-03 22:22 ` Matt Brown
2017-06-03 22:22 ` Matt Brown
2017-06-04 3:37 ` Peter Dolding
2017-06-04 3:37 ` Peter Dolding
2017-06-04 3:37 ` Peter Dolding
2017-05-30 15:20 ` Casey Schaufler
2017-05-30 15:20 ` Casey Schaufler
2017-05-30 16:09 ` Matt Brown
2017-05-30 16:09 ` Matt Brown
2017-06-04 6:29 ` Boris Lukashev
2017-06-04 6:29 ` Boris Lukashev
2017-05-31 2:48 ` James Morris
2017-05-31 2:48 ` James Morris
2017-05-31 4:10 ` Matt Brown
2017-05-31 4:10 ` Matt Brown
2017-05-30 0:15 ` Matt Brown
2017-05-30 0:15 ` [kernel-hardening] " Matt Brown
2017-05-30 0:15 ` Matt Brown
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