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From: Kees Cook <keescook@chromium.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Kees Cook <keescook@chromium.org>,
	Jiri Slaby <jirislaby@kernel.org>,
	Simon Brand <simon.brand@postadigitale.de>,
	linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
Subject: [PATCH 0/2] tty: Allow TIOCSTI to be disabled
Date: Fri, 14 Oct 2022 21:16:22 -0700	[thread overview]
Message-ID: <20221015041352.never.966-kees@kernel.org> (raw)

Hi,

This is so very long over-due. We just need to do this and put an end
to this legacy operation.

Repeating the commit log from patch 2:

    TIOCSTI continues its long history of being used in privilege escalation
    attacks[1]. Prior attempts to provide a mechanism to disable this have
    devolved into discussions around creating full-blown LSMs to provide
    arbitrary ioctl filtering, which is hugely over-engineered -- only
    TIOCSTI is being used this way. 3 years ago OpenBSD entirely removed
    TIOCSTI[2], Android has had it filtered for longer[3], and the tools that
    had historically used TIOCSTI either do not need it, are not commonly
    built with it, or have had its use removed.

    Provide a simple CONFIG and global sysctl to disable this for the system
    builders who have wanted this functionality for literally decades now,
    much like the ldisc_autoload CONFIG and sysctl.

    [1] https://lore.kernel.org/linux-hardening/Y0m9l52AKmw6Yxi1@hostpad
    [2] https://undeadly.org/cgi?action=article;sid=20170701132619
    [3] https://lore.kernel.org/lkml/CAFJ0LnFGRuEEn1tCLhoki8ZyWrKfktbF+rwwN7WzyC_kBFoQVA@mail.gmail.com/

Thanks,

-Kees

Kees Cook (2):
  tty: Move sysctl setup into "core" tty logic
  tty: Allow TIOCSTI to be disabled

 drivers/tty/Kconfig     | 19 +++++++++++++++++
 drivers/tty/tty.h       |  2 +-
 drivers/tty/tty_io.c    | 47 +++++++++++++++++++++++++++++++++++++++--
 drivers/tty/tty_ldisc.c | 38 +--------------------------------
 4 files changed, 66 insertions(+), 40 deletions(-)

-- 
2.34.1


             reply	other threads:[~2022-10-15  4:16 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-15  4:16 Kees Cook [this message]
2022-10-15  4:16 ` [PATCH 1/2] tty: Move sysctl setup into "core" tty logic Kees Cook
2022-10-15  4:16 ` [PATCH 2/2] tty: Allow TIOCSTI to be disabled Kees Cook

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