linux-kernel - Re: [PATCH v2] tty: Permit some TIOCL_SETSEL modes without CAP_SYS

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <202501100850.5E4D0A5@keescook>
Date: Fri, 10 Jan 2025 08:50:57 -0800
From: Kees Cook <kees@...nel.org>
To: Günther Noack <gnoack@...gle.com>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jann Horn <jannh@...gle.com>,
	Hanno Böck <hanno@...eck.de>,
	Jiri Slaby <jirislaby@...nel.org>, linux-hardening@...r.kernel.org,
	regressions@...ts.linux.dev, linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Subject: Re: [PATCH v2] tty: Permit some TIOCL_SETSEL modes without
 CAP_SYS_ADMIN

On Fri, Jan 10, 2025 at 02:21:22PM +0000, Günther Noack wrote:
> With this, processes without CAP_SYS_ADMIN are able to use TIOCLINUX with
> subcode TIOCL_SETSEL, in the selection modes TIOCL_SETPOINTER,
> TIOCL_SELCLEAR and TIOCL_SELMOUSEREPORT.
> 
> TIOCL_SETSEL was previously changed to require CAP_SYS_ADMIN, as this IOCTL
> let callers change the selection buffer and could be used to simulate
> keypresses.  These three TIOCL_SETSEL selection modes, however, are safe to
> use, as they do not modify the selection buffer.
> 
> This fixes a mouse support regression that affected Emacs (invisible mouse
> cursor).
> 
> Cc: stable@...r.kernel.org
> Link: https://lore.kernel.org/r/ee3ec63269b43b34e1c90dd8c9743bf8@finder.org
> Fixes: 8d1b43f6a6df ("tty: Restrict access to TIOCLINUX' copy-and-paste subcommands")
> Signed-off-by: Günther Noack <gnoack@...gle.com>

Reviewed-by: Kees Cook <kees@...nel.org>

-- 
Kees Cook