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Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN

From "Serge E. Hallyn" <serge@hallyn.com>
Newsgroups linux.kernel
Subject Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN
Date 2017-06-02 20:20 +0200
Message-ID <tNZl0-4FP-9@gated-at.bofh.it> (permalink)
References (5 earlier) <tNW3M-2sh-21@gated-at.bofh.it> <tNWQ9-314-17@gated-at.bofh.it> <tNXjb-3qc-17@gated-at.bofh.it> <tNY5z-3Ka-5@gated-at.bofh.it> <tNYIi-4cS-9@gated-at.bofh.it>
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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

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[PATCH v7 2/2] security: tty: make TIOCSTI ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-29 23:40 +0200
  Re: [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require  CAP_SYS_ADMIN Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-05-30 00:30 +0200
    Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Boris Lukashev <blukashev@sempervictus.com> - 2017-05-30 02:00 +0200
      Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Casey Schaufler <casey@schaufler-ca.com> - 2017-05-30 02:30 +0200
        Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-30 04:10 +0200
          Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Casey Schaufler <casey@schaufler-ca.com> - 2017-05-30 04:50 +0200
            Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-30 05:20 +0200
              Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-05-30 14:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-30 18:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Daniel Micay <danielmicay@gmail.com> - 2017-05-30 18:50 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Stephen Smalley <sds@tycho.nsa.gov> - 2017-05-30 20:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Nick Kralevich <nnk@google.com> - 2017-05-30 20:50 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-30 21:00 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Daniel Micay <danielmicay@gmail.com> - 2017-05-30 22:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-31 01:10 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Daniel Micay <danielmicay@gmail.com> - 2017-05-31 01:50 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-31 02:00 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-05-31 01:00 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-31 01:20 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-05-31 02:00 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Kees Cook <keescook@chromium.org> - 2017-06-01 04:40 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-06-01 15:10 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-01 19:20 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-06-01 23:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Kees Cook <keescook@chromium.org> - 2017-06-01 21:00 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-06-01 23:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-06-02 16:50 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-02 17:40 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-06-02 18:10 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-02 19:00 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-06-02 19:40 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN "Serge E. Hallyn" <serge@hallyn.com> - 2017-06-02 20:20 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-06-02 21:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Kees Cook <keescook@chromium.org> - 2017-06-02 21:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-06-02 21:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-06-02 22:10 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Nick Kralevich <nnk@google.com> - 2017-06-02 22:20 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-06-02 22:50 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make  TIOCSTI ioctl require CAP_SYS_ADMIN Alan Cox <gnomes@lxorguk.ukuu.org.uk> - 2017-06-04 00:10 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-06-04 00:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Peter Dolding <oiaohm@gmail.com> - 2017-06-04 05:40 +0200
              Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Casey Schaufler <casey@schaufler-ca.com> - 2017-05-30 17:30 +0200
                Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-30 18:10 +0200
        Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Boris Lukashev <blukashev@sempervictus.com> - 2017-06-04 08:30 +0200
      Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN James Morris <jmorris@namei.org> - 2017-05-31 04:50 +0200
        Re: [kernel-hardening] Re: [PATCH v7 2/2] security: tty: make TIOCSTI  ioctl require CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-31 06:20 +0200
    Re: [PATCH v7 2/2] security: tty: make TIOCSTI ioctl require  CAP_SYS_ADMIN Matt Brown <matt@nmatt.com> - 2017-05-30 02:20 +0200

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